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NUREG-1805

Fire Dynamics Tools (FDT ): s

Quantitative Fire Hazard 

Analysis Methods for the

U.S. Nuclear Regulatory Commission

Fire Protection Inspection Program

Final Report

Manuscript Completed: October 2004

Date Published: December 2004

Prepared by

Naeem Iqbal, Mark Henry Salley

Sunil Weerakkody, NRC Project Manager

Prepared for

Division of System Safety and Analysis

Office of Nuclear Reactor Regulation

U.S. Nuclear Regulatory Commission

Washington, DC 20555-0001

iii

ABSTRACT

The U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Reactor Regulation (NRR),

Division of Systems Safety and Analysis (DSSA), Plant Systems Branch (SPLB), Fire Protection

Engineering and Special Projects Section, has developed quantitative methods, known as

“Fire Dynamics Tools” (FDT ), to assist regional fire protection inspectors in performing fire hazard s

analysis (FHA). These methods have been implemented in spreadsheets and taught at the NRC’s

quarterly regional inspector workshops. FDT were developed using state-of-the-art fire dynamics s

equations and correlations that were preprogrammed and locked into Microsoft Excel®

spreadsheets. These FDT will enable the inspector to perform quick, easy, first-order calculations s

for the potential fire scenarios using today’s state-of-the-art principles of fire dynamics. Each FDTs

spreadsheet also contains a list of the physical and thermal properties of the materials commonly

encountered in nuclear power plants. This NUREG-series report addresses the technical bases

for FDT , which were derived from the principles developed primarily in the Society of Fire s

Protection Engineers (SFPE) Handbook of Fire Protection Engineering, National Fire Protection

Association (NFPA) Fire Protection Handbook, and other fire science literature. The subject matter

of this report covers many aspects of fire dynamics and contains descriptions of the most important

fire processes. A significant number of examples, reference tables, illustrations, and conceptual

drawings are presented in this report to expand the inspector’s appreciation in visualizing and

retaining the material and understanding calculation methods.
iv
v

CONTENTS

Page

Abstract ............ ............ ............ ............ ............ ....... iii

List of Fire Dynamics Tools ............ ............ ............ ............ . xxvii

Disclaimer ............ ............ ............ ............ ............ .... xxxi

The Authors ............ ............ ............ ............ ............ . xxxiii

Acknowledgments ............ ............ ............ ............ ........ xxxv

Executive Summary ............ ............ ............ ............ ....... xxxvii

How To Use this NUREG and the FDT ............ ............ ............ ....

s

xxxix

Abbreviations ............ ............ ............ ............ ............ . . xli

Nomenclature ............ ............ ............ ............ ............ . xlvii

Chapter 1. Introduction ............ ............ ............ ............ ... 1-1

1.1 Purpose ............ ............ ............ ............ 1-1

1.2 Objective ............ ............ ............ ........... 1-1

1.3 Regulatory Background on Fire Protection for Nuclear Power Plants 1-1

1.4 Fire Hazard Analysis for Nuclear Power Plants . . . . . . . . . . . . . . . . . 1-3

1.5 Fire Protection Inspection Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

1.6 Fire Scenario Development for Nuclear Power Plants . . . . . . . . . . . . 1-4

1.7 Process of Fire Development ............ ............ ....... 1-4

1.8 The Fire Hazards ............ ............ ............ .... 1-6

1.8.1 Combustible Materials Found in Nuclear Power Plants . . . . . 1-7

1.8.1.1 Transient Combustibles . . . . . . . . . . . . . . . . . . . . . 1-7

1.8.1.2 In Situ Combustibles . . . . . . . . . . . . . . . . . . . . . . . . 1-7

1.8.1.3 Liquid Fuels ............ ............ ....... 1-8

1.8.1.4 Explosive and Flammable Gases . . . . . . . . . . . . . . 1-8

1.9 Location of the Fire ............ ............ ............ ... 1-9

1.10 Risk-Informed Performance-Based Fire Protection . . . . . . . . . . . . . . 1-9

1.11 Data Sources for Combustible Materials Found in Nuclear Power Plants 1-10

1.12 References ............ ............ ............ ........ 1-12

1.13 Additional Readings ............ ............ ............ . 1-13
vi

CONTENTS (continued)

Chapter 2. Predicting Hot Gas Layer Temperature and Smoke Layer Height in a Room Fire

with Natural and Forced Ventilation ............ ............ ........ 2-1

2.1 Objectives ............ ............ ............ .......... 2-1

2.2 Introduction ............ ............ ............ ......... 2-1

2.3 Compartment Fire Growth ............ ............ .......... 2-1

2.3.1 Stages of Compartment Fires . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.3.2 Ventilation-Limited or Ventilation-Controlled Fires . . . . . . . . . 2-4

2.3.3 Fuel-Limited Fires ............ ............ .......... 2-4

2.4 Compartment Ventilation ............ ............ ........... 2-4

2.4.1 Definitions ............ ............ ............ .... 2-6

2.5 Temperature ............ ............ ............ ........ 2-6

2.6 Estimating Hot Gas Layer Temperature . . . . . . . . . . . . . . . . . . . . . . . 2-8

2.6.1 Natural Ventilation: Method of McCaffrey, Quintiere, and 

Harkleroad (MQH) ............ ............ ........... 2-8

2.6.2 Natural Ventilation (Compartment Closed): Method of Beyler . 2-12

2.6.3 Forced Ventilation: Method of Foote, Pagni, and Alvares (FPA) 2-12

2.6.4 Forced Ventilation: Method of Deal and Beyler . . . . . . . . . . 2-13

2.7 Estimating Smoke Layer Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-14

2.7.1 Smoke Layer ............ ............ ............ . 2-15

2.7.2 Smoke Layer Interface Position . . . . . . . . . . . . . . . . . . . . . . 2-15

2.7.3 Natural Ventilation (Smoke Filling): 

The Non-Steady-State Yamana and Tanaka Method . . . . . . 2-15

2.8 Data Sources for Heat Release Rate . . . . . . . . . . . . . . . . . . . . . . . . 2-17

2.9 Identification of Fire Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19

2.10 Assumption and Limitations ............ ............ ....... 2-23

2.11 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . . 2-24

2.12 Cautions ............ ............ ............ .......... 2-25

2.13 Summary ............ ............ ............ .......... 2-25

2.14 References ............ ............ ............ ........ 2-26

2.15 Additional Readings ............ ............ ............ . 2-28

2.16 Problems ............ ............ ............ .......... 2-29
vii

CONTENTS (continued)

Chapter 3. Estimating Burning Characteristics of Liquid Pool Fire, Heat Release Rate,

Burning Duration, and Flame Height ............ ............ ........ 3-1

3.1 Objectives ............ ............ ............ .......... 3-1

3.2 Heat Release Rate ............ ............ ............ ... 3-1

3.2.1 Enclosure Effects on Mass Loss Rate . . . . . . . . . . . . . . . . . . . 3-5

3.2.2 Pool Fires ............ ............ ............ .... 3-5

3.3 Burning Duration ............ ............ ............ ..... 3-7

3.3.1 Burning Duration of a Pool Fire . . . . . . . . . . . . . . . . . . . . . . . . 3-8

3.4 Flame Height ............ ............ ............ ........ 3-8

3.4.1 Flame Extensions Under Ceiling . . . . . . . . . . . . . . . . . . . . . . 3-12

3.4.2 Flame Impingement ............ ............ ........ 3-12

3.4.3 Flame Temperature ............ ............ ........ 3-12

3.4.4 Flames Temperatures of Open Fires . . . . . . . . . . . . . . . . . . . 3-14

3.4.5 Flame Temperatures in Room Fires . . . . . . . . . . . . . . . . . . . 3-14

3.4.6 Adiabatic Flame Temperature . . . . . . . . . . . . . . . . . . . . . . . . 3-15

3.4.7 Temperatures of Objects ............ ............ .... 3-16

3.4.8 Flame Height Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . 3-16

3.5 Assumptions and Limitations ............ ............ ...... 3-18

3.6 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . . 3-19

3.7 Cautions ............ ............ ............ .......... 3-19

3.8 Summary ............ ............ ............ .......... 3-19

3.9 References ............ ............ ............ ........ 3-20

3.10 Additional Readings ............ ............ ............ . 3-21

3.11 Problems ............ ............ ............ .......... 3-22

Chapter 4. Estimating Wall Fire Flame Height, Line Fire Flame Height Against the Wall,

and Corner Fire Flame Height ............ ............ ............ 4-1

4.1 Objectives ............ ............ ............ .......... 4-1

4.2 Introduction ............ ............ ............ ......... 4-1

4.3 Flame Height Correlations for Wall Fires, Line Fires, and Corner Fires 4-1

4.3.1 Wall Fire Flame Height Correlation . . . . . . . . . . . . . . . . . . . . . 4-2

4.3.2 Line Fire Flame Height Correlation . . . . . . . . . . . . . . . . . . . . . 4-2

4.3.3 Corner Fire Flame Height Correlation . . . . . . . . . . . . . . . . . . . 4-4

4.4 Assumptions and Limitations ............ ............ ....... 4-5

4.5 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . . . 4-5

4.6 Cautions ............ ............ ............ ........... 4-5

4.7 Summary ............ ............ ............ ........... 4-5

4.8 References ............ ............ ............ ......... 4-6

4.9 Problems ............ ............ ............ ........... 4-7
viii

CONTENTS (continued)

Chapter 5. Estimating Radiant Heat Flux from Fire to a Target Fuel . . . . . . . . . . . . . . . . 5-1

5.1 Objectives ............ ............ ............ .......... 5-1

5.2 Introduction ............ ............ ............ ......... 5-1

5.3 Critical Heat Flux to a Target ............ ............ ....... 5-2

5.3.1 Point Source Radiation Model . . . . . . . . . . . . . . . . . . . . . . . . . 5-3

5.3.2 Solid Flame Radiation Model with Target At and Above

Ground Level ............ ............ ............ . . 5-5

5.3.2.1 Emissive Power ............ ............ .... 5-6

1 2 6

5.3.2.2 Configuration Factor F under Wind-Free Conditions 5-7

1 2 6

5.3.2.3 Configuration Factor F in Presence of Wind . . . 5-11

5.4 Method of Estimating Thermal Radiation from Hydrocarbon Fireball . . 5-15

5.4.1 Radiation Due to BLEVEs with Accompanying Fireball . . . . . 5-15

5.5 Assumptions and Limitations ............ ............ ...... 5-17

5.6 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . . 5-17

5.7 Cautions ............ ............ ............ .......... 5-18

5.8 Summary ............ ............ ............ .......... 5-18

5.9 References ............ ............ ............ ........ 5-19

5.10 Additional Readings ............ ............ ............ . 5-20

5.11 Problems ............ ............ ............ .......... 5-21

Chapter 6. Estimating the Ignition Time of a Target Fuel

Exposed to a Constant Radiative Heat Flux . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

6.1 Objectives ............ ............ ............ .......... 6-1

6.2 Introduction ............ ............ ............ ......... 6-1

6.3 Ignition Sources and Fire Development . . . . . . . . . . . . . . . . . . . . . . . 6-3

6.4 Ignition Time for Thermally Thick Materials . . . . . . . . . . . . . . . . . . . . .6-3

6.4.1 Method of Tewarson ............ ............ ........ 6-4

6.4.2 Method of Mikkola and Wichman . . . . . . . . . . . . . . . . . . . . . . 6-8

6.4.3 Method of Quintiere and Harkleroad . . . . . . . . . . . . . . . . . . . . 6-8

6.4.4 Method of Janssens ............ ............ ........ 6-9

6.4.5 Method of Toal, Silcock, and Shields . . . . . . . . . . . . . . . . . . 6-12

6.5 Assumptions and Limitations ............ ............ ...... 6-14

6.6 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . . 6-14

6.7 Cautions ............ ............ ............ .......... 6-14

6.8 Summary ............ ............ ............ .......... 6-14

6.9 References ............ ............ ............ ........ 6-15

6.10 Additional Readings ............ ............ ............ . 6-15

6.11 Problems ............ ............ ............ .......... 6-16
ix

CONTENTS (continued)

Chapter 7. Estimating the Full-Scale Heat Release Rate of a Cable Tray Fire . . . . . . . . 7-1

7.1 Objectives ............ ............ ............ .......... 7-1

7.2 Introduction ............ ............ ............ ......... 7-1

7.3 Cable Tray Fire Burning Mode Classification . . . . . . . . . . . . . . . . . . . 7-2

7.4 Cable Tray Heat Release Rate ............ ............ ...... 7-3

7.5 Cable Failure Criteria (Critical Temperature and Critical Heat Flux) . . 7-5

7.6 Assumptions and Limitations ............ ............ ....... 7-6

7.7 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . . . 7-6

7.8 Cautions ............ ............ ............ ........... 7-6

7.9 Summary ............ ............ ............ ........... 7-6

7.10 References ............ ............ ............ ......... 7-7

7.11 Additional Readings ............ ............ ............ . . 7-7

7.12 Problems ............ ............ ............ ........... 7-8

Chapter 8. Estimating Burning Duration of Solid Combustibles ............ ........ 8-1

8.1 Objectives ............ ............ ............ .......... 8-1

8.2 Introduction ............ ............ ............ ......... 8-1

8.3 Burning Duration of Solid Combustibles . . . . . . . . . . . . . . . . . . . . . . . 8-1

8.4 Assumptions and Limitations ............ ............ ....... 8-4

8.5 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . . . 8-4

8.6 Cautions ............ ............ ............ ........... 8-4

8.7 Summary ............ ............ ............ ........... 8-4

8.8 References ............ ............ ............ ......... 8-4

8.9 Problems ............ ............ ............ ........... 8-5

Chapter 9. Estimating the Centerline Temperature of a Buoyant Fire Plume . . . . . . . . . . 9-1

9.1 Objectives ............ ............ ............ .......... 9-1

9.2 Introduction ............ ............ ............ ......... 9-1

9.3 Fire Plume Characteristics ............ ............ ......... 9-2

9.3.1 Plume Temperature ............ ............ ......... 9-4

9.4 Application for Centerline Fire Plume Correlation . . . . . . . . . . . . . . . . 9-7

9.5 Assumptions and Limitations ............ ............ ....... 9-7

9.6 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . . . 9-7

9.7 Cautions ............ ............ ............ ........... 9-8

9.8 Summary ............ ............ ............ ........... 9-8

9.9 References ............ ............ ............ ......... 9-9

9.10 Additional Readings ............ ............ ............ . . 9-9

9.11 Problems ............ ............ ............ .......... 9-10
x

CONTENTS (continued)

Chapter 10. Estimating Sprinkler Response Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1

10.1 Objectives ............ ............ ............ ......... 10-1

10.2 Introduction ............ ............ ............ ........ 10-1

10.3 Operating Principles of Automatic Sprinklers . . . . . . . . . . . . . . . . . . 10-3

10.3.1 Heat Transfer Characteristics for Heat-Sensitive Elements . 10-4

10.3.2 Sprinkler Dynamics ............ ............ ....... 10-5

10.3.3 Temperature Ratings of Automatic Sprinklers . . . . . . . . . . . 10-6

10.3.4 Sprinkler Activation ............ ............ ....... 10-9

10.3.5 Sprinkler Spray Interaction with Plume . . . . . . . . . . . . . . . 10-11

10.4 Assumptions and Limitations ............ ............ ..... 10-12

10.5 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . 10-12

10.6 Cautions ............ ............ ............ ......... 10-13

10.7 Summary ............ ............ ............ ......... 10-13

10.8 References ............ ............ ............ ....... 10-13

10.9 Additional Readings ............ ............ ............ 10-14

10.10 Problems ............ ............ ............ ......... 10-15

Chapter 11. Estimating Smoke Detector Response Time . . . . . . . . . . . . . . . . . . . . . . . . 11-1

11.1 Objectives ............ ............ ............ ......... 11-1

11.2 Introduction ............ ............ ............ ........ 11-1

11.3 Characteristics of Smoke Production . . . . . . . . . . . . . . . . . . . . . . . . 11-2

11.4 Operating Principles of Smoke Detectors . . . . . . . . . . . . . . . . . . . . . 11-3

11.5 Smoke Detector Response ............ ............ ........ 11-6

11.5.1 Method of Alpert ............ ............ .......... 11-7

11.5.2 Method of Mowrer ............ ............ ........ 11-9

11.5.3 Method of Milke ............ ............ ......... 11-10

11.6 Assumptions and Limitations ............ ............ ..... 11-11

11.7 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . 11-12

11.8 Cautions ............ ............ ............ ......... 11-12

11.9 Summary ............ ............ ............ ......... 11-12

11.10 References ............ ............ ............ ....... 11-13

11.11 Additional Readings ............ ............ ............ 11-13

11.12 Problems ............ ............ ............ ......... 11-14
xi

CONTENTS (continued)

Chapter 12. Estimating Heat Detector Response Time . . . . . . . . . . . . . . . . . . . . . . . . . . 12-1

12.1 Objectives ............ ............ ............ ......... 12-1

12.2 Introduction ............ ............ ............ ........ 12-1

12.3 Underwriters’ Laboratories, Inc., Listing Information

for Heat-Detecting Automatic Fire Detectors . . . . . . . . . . . . . . . . . . 12-1

12.4 Operating Principle of Heat Detectors . . . . . . . . . . . . . . . . . . . . . . . . 12-2

12.4.1 Fixed-Temperature Heat Detectors . . . . . . . . . . . . . . . . . . . 12-3

12.4.1.1 Fusible-Element Type . . . . . . . . . . . . . . . . . . . . 12-3

12.4.1.2 Continuous Line Type . . . . . . . . . . . . . . . . . . . . 12-3

12.4.1.3 Bimetallic Type ............ ............ . . 12-3

12.4.2 Rate Compensation Heat Detectors . . . . . . . . . . . . . . . . . . 12-4

12.4.3 Rate-of-Rise Heat Detectors . . . . . . . . . . . . . . . . . . . . . . . . 12-4

12.4.4 Pneumatic Heat Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . 12-4

12.4.4.1 Line-Type Heat Detectors . . . . . . . . . . . . . . . . . 12-5

12.4.5 Combination Heat Detectors . . . . . . . . . . . . . . . . . . . . . . . . 12-5

12.4.6 Electronic Spot-Type Thermal Detectors . . . . . . . . . . . . . . . 12-5

12.5 Fixed-Temperature Heat Detector Activation . . . . . . . . . . . . . . . . . . 12-6

12.6 Assumptions and Limitations ............ ............ ..... 12-10

12.7 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . 12-11

12.8 Cautions ............ ............ ............ ......... 12-11

12.9 Summary ............ ............ ............ ......... 12-11

12.10 References ............ ............ ............ ....... 12-12

12.11 Additional Readings ............ ............ ............ 12-12

12.12 Problems ............ ............ ............ ......... 12-13

Chapter 13. Predicting Compartment Flashover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-1

13.1 Objectives ............ ............ ............ ......... 13-1

13.2 Introduction ............ ............ ............ ........ 13-1

13.3 Compartment Flashover ............ ............ .......... 13-5

13.3.1 Method of Predicting Compartment Flashover . . . . . . . . . . 13-5

13.3.1.1 Method of McCaffrey, Quintiere, and Harkleroad

(MQH) ............ ............ ......... 13-5

13.3.1.2 Method of Babrauskas . . . . . . . . . . . . . . . . . . . . 13-6

13.3.1.3 Method of Thomas ............ ........... 13-6

13.3.2 Method of Predicting Compartment Post-Flashover Temperature 13-7

13.4 Fire Severity ............ ............ ............ ....... 13-8

13.4.1 Method of Margaret Law ............ ............ ... 13-8

13.5 Assumptions and Limitations ............ ............ ..... 13-10

13.6 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . 13-10

13.7 Cautions ............ ............ ............ ......... 13-10

13.8 Summary ............ ............ ............ ......... 13-10

13.9 References ............ ............ ............ ....... 13-11

13.10 Problems ............ ............ ............ ......... 13-13
xii

CONTENTS (continued)

Chapter 14. Estimating Pressure Rise Attributable to a Fire in a Closed Compartment . 14-1

14.1 Objectives ............ ............ ............ ......... 14-1

14.2 Introduction ............ ............ ............ ........ 14-1

14.3 Definition of Pressure ............ ............ ............ 14-2

14.4 Pressure Rise Calculations ............ ............ ........ 14-3

14.5 Assumptions and Limitations ............ ............ ...... 14-3

14.6 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . . 14-4

14.7 Cautions ............ ............ ............ .......... 14-4

14.8 Summary ............ ............ ............ .......... 14-4

14.9 References ............ ............ ............ ........ 14-4

14.10 Problems ............ ............ ............ .......... 14-5

Chapter 15. Estimating the Pressure Increase and Explosive Energy Release

Associated with Explosions ............ ............ ............ ... 15-1

15.1 Objectives ............ ............ ............ ......... 15-1

15.2 Introduction ............ ............ ............ ........ 15-1

15.3 Explosion Hazard ............ ............ ............ ... 15-3

15.4 Explosive Range ............ ............ ............ .... 15-4

15.5 Backdraft Explosion ............ ............ ............ . 15-4

15.6 Smoke Explosion ............ ............ ............ ... 15-4

15.7 Unconfined and Confined Explosions . . . . . . . . . . . . . . . . . . . . . . . . 15-5

15.8 Estimating the Effects of Explosions . . . . . . . . . . . . . . . . . . . . . . . . . 15-7

15.8.1 Estimating Explosive Energy Release in a Confined Explosion 15-9

15.8.2 TNT Mass Equivalent Calculations . . . . . . . . . . . . . . . . . . 15-10

15.8.3 Blast Effects ............ ............ ............ 15-11

15.9 Effects of Pressure on Humans and Environments . . . . . . . . . . . . 15-12

15.10 Effects of Pressure on Components . . . . . . . . . . . . . . . . . . . . . . . . 15-13

15.11 Estimating the Pressure Increase Attributable to a Confined Explosion 15-14

15.12 Assumptions and Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-15

15.13 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . 15-15

15.14 Cautions ............ ............ ............ ......... 15-15

15.15 Summary ............ ............ ............ ......... 15-16

15.16 References ............ ............ ............ ....... 15-17

15.17 Additional Readings ............ ............ ............ 15-17

15.18 Problems ............ ............ ............ ......... 15-18
xiii

CONTENTS (continued)

Chapter 16. Calculating the Rate of Hydrogen Gas Generation in Battery Rooms . . . . . 16-1

16.1 Objectives ............ ............ ............ ......... 16-1

16.2 Introduction ............ ............ ............ ........ 16-1

16.3 Combustion of Hydrogen Gas ............ ............ ...... 16-2

16.4 Ignition of Hydrogen Gas ............ ............ ......... 16-4

16.4.1 Battery as an Ignition Source . . . . . . . . . . . . . . . . . . . . . . . . 16-5

16.4.2 Control of Hydrogen Gas Combustion . . . . . . . . . . . . . . . . . 16-5

16.5 Fire Protection Code Requirements for Battery Rooms . . . . . . . . . . 16-6

16.6 Method of Calculating the Rate of Hydrogen Generation in Battery Rooms 16-7

16.7 Method of Calculating Flammable Gas and Vapor Concentration

Buildup in Enclosed Spaces ............ ............ ....... 16-8

16.8 Method of Calculating Flammable Gas and Vapor Concentration

Buildup Time in Enclosed Spaces ............ ............ ... 16-9

16.9 Assumptions and Limitations ............ ............ ..... 16-10

16.10 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . 16-10

16.11 Cautions ............ ............ ............ ......... 16-11

16.12 Summary ............ ............ ............ ......... 16-11

16.13 References ............ ............ ............ ....... 16-12

16.14 Problems ............ ............ ............ ......... 16-13

Chapter 17. Calculating the Fire Resistance of Structural Steel Members ............ 17-1

17.1 Objectives ............ ............ ............ ......... 17-1

17.2 Introduction ............ ............ ............ ........ 17-1

17.3 Fire Resistance of Buildings ............ ............ ....... 17-3

17.4 Fire Resistance of Structural Members . . . . . . . . . . . . . . . . . . . . . . . 17-5

17.4.1 Fire Resistance and Temperature Limits of Steel Elements 17-5

17.4.2 Fire Resistance and Temperature Limits of Reinforced Concrete

Elements ............ ............ ............ .... 17-5

17.5 Failure Criteria for Structural Members . . . . . . . . . . . . . . . . . . . . . . . 17-6

17.6 Fire Walls and Fire Barrier Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-7

17.7 Fire Resistance Coatings for Structural Steel . . . . . . . . . . . . . . . . . . 17-8

17.8 Calculating Fire Resistance or Endurance . . . . . . . . . . . . . . . . . . . 17-10

17.8.1 Equivalent Fire Resistance of Structural Steel . . . . . . . . . . 17-10

17.8.2 Steel Column (Unprotected) . . . . . . . . . . . . . . . . . . . . . . . 17-11

17.8.3 Steel Column (Protected with Gypsum Wallboard) . . . . . . 17-12

17.8.4 Steel Column (with Low-Density Protection) . . . . . . . . . . . 17-13

17.8.5 Steel Column (Protected with Spray-On Materials) . . . . . . 17-14

17.8.6 Steel Column (Protected by Concrete) . . . . . . . . . . . . . . . 17-15

17.8.7 Steel Beams ............ ............ ............ 17-16

17.8.7.1 Beam Substitution Correlation for Structural Steel

Beams Protected by Spray-On Materials . . . . . . 17-17

17.8.7.2 Column Substitution Correlation for Structural Steel

Columns Protected by Spray-On Materials . . . . 17-18
xiv

CONTENTS (continued)

17.8.8 Numerical Method to Estimate the Temperature Increase

in Structural Steel Elements . . . . . . . . . . . . . . . . . . . . . . . . 17-18

17.8.8.1 Unprotected Structural Steel Sections . . . . . . . . 17-19

17.8.8.2 Protected Structural Steel Sections . . . . . . . . . . 17-21

17.9 Assumptions and Limitations ............ ............ ..... 17-23

17.10 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . 17-23

17.11 Cautions ............ ............ ............ ......... 17-23

17.12 Summary ............ ............ ............ ......... 17-23

17.13 References ............ ............ ............ ....... 17-24

17.14 Problems ............ ............ ............ ......... 17-25

Chapter 18. Estimating Visibility Through Smoke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-1

18.1 Objectives ............ ............ ............ ......... 18-1

18.2 Introduction ............ ............ ............ ........ 18-1

18.3 Smoke Obscuration ............ ............ ............ . . 18-1

18.4 Effect of Smoke on Nuclear Power Plants . . . . . . . . . . . . . . . . . . . . 18-2

18.5 Estimating Visibility Through Smoke — Jin Method . . . . . . . . . . . . . 18-2

18.6 Assumptions and Limitations ............ ............ ...... 18-5

18.7 Required Input for Spreadsheet Calculations . . . . . . . . . . . . . . . . . . 18-5

18.8 Cautions ............ ............ ............ .......... 18-5

18.9 Summary ............ ............ ............ .......... 18-6

18.10 References ............ ............ ............ ........ 18-6

18.10 Problems ............ ............ ............ .......... 18-7

Index ............ ............ ............ ............ ............ ..... Index-1
xv

Appendices

Page

A. Nuclear Power Plant Electrical Cable Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . A-1

A.1 Introduction ............ ............ ............ ............ ... A-1

A.2 Electrical Cable Construction ............ ............ ............ . A-2

A.3 Description of Cables ............ ............ ............ ....... A-3

A.4 Cable Materials ............ ............ ............ ............ A-7

A.4.1 Thermoplastic Materials ............ ............ ........... A-7

A.4.2 Thermoset Materials ............ ............ ............ . . A-8

A.5 Cable Failure Threshold and Time to Damage . . . . . . . . . . . . . . . . . . . . . . . . A-9

A.5.1 Theory ............ ............ ............ ............ . A-9

A.5.2 Temperature Thresholds — Thermoset Cables . . . . . . . . . . . . . . . . . A-9

A.5.3 Temperature Thresholds — Thermoplastic Cables . . . . . . . . . . . . . A-12

A.5.4 Radiant Heating Failure Criteria — Cables . . . . . . . . . . . . . . . . . . . . A-14

A.5.5 Basis for Cable Damage Timing Estimates . . . . . . . . . . . . . . . . . . . . A-15

A.5.6 Temperature Exposures — Thermoset Cables . . . . . . . . . . . . . . . . . A-15

A.5.7 Temperature Exposures — Thermoplastic Cables . . . . . . . . . . . . . . A-17

A.5.8 Radiant Exposures — Thermoset and Thermoplastic Cables . . . . . A-19

A.6 References ............ ............ ............ ............ . . A-20

A.7 Additional Readings ............ ............ ............ ....... A-20

B. Fundamentals of Fire Protection ............ ............ ............ ..... B-1

B.1 T-Squared (t ) Fire Power Law Heat Release Rate . . . . . . . . . . . . . . . . . . . .

2 B-1

B.1.1 Introduction ............ ............ ............ ......... B-1

B.1.2 t Heat Release Rate ............ ............ ............ . .

2 B-1

B.1.3 References ............ ............ ............ ........ B-10

B.2 Elements of Hydraulic and Electrical Systems . . . . . . . . . . . . . . . . . . . . . . . B-11

B.2.1 References ............ ............ ............ ........ B-12

B.3 Classes of Fires ............ ............ ............ .......... B-13

B.3.1 References ............ ............ ............ ........ B-13

B.4 Classification of Hazards ............ ............ ............ ... B-14

B.4.1 Light (Low) Hazard ............ ............ ............ . . B-14

B.4.2 Ordinary (Moderate) Hazard ............ ............ ....... B-14

B.4.3 Extra (High) Hazard ............ ............ ............ . B-14

B.4.4 References ............ ............ ............ ........ B-14

B.5 Classes of Fires and Extinguishing Agents . . . . . . . . . . . . . . . . . . . . . . . . . . B-15

B.6 Classification of Flammable and Combustible Liquids . . . . . . . . . . . . . . . . . B-17

B.6.1 Flammable Liquid ............ ............ ............ ... B-17

B.6.2 Combustible Liquid Classifications . . . . . . . . . . . . . . . . . . . . . . . . . . B-18

B.6.3 Storage of Flammable and Combustible Liquids . . . . . . . . . . . . . . . B-20

B.6.4 Flammable Combustible Storage Cabinets . . . . . . . . . . . . . . . . . . . . B-21

B.6.5 Definitions ............ ............ ............ ......... B-21

B.6.6 Hazardous Materials ............ ............ ............ . B-22

B.6.7 References ............ ............ ............ ........ B-23

B.7 Classification of Flammable Gases ............ ............ ........ B-24

B.7.1 Classification ............ ............ ............ ....... B-24

B.7.2 Definitions ............ ............ ............ ......... B-24

B.7.3 References ............ ............ ............ ........ B-24
xvi

Appendices (continued)

B.8 Flammability Hazards of Gases ............ ............ .......... B-25

B.8.1 Flammability Potential of Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-25

B.8.2 Flammability Potential of Hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . B-26

B.8.3 Flammable Limits, Detonable Limits, and Potential for

Deflagration-to-Detonation Transitions . . . . . . . . . . . . . . . . . . . . . . . B-26

B.8.4 Flammable Gas Generation ............ ............ ....... B-26

B.8.5 Explosion Prevention Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-27

B.8.6 References ............ ............ ............ ........ B-28

B.9 Combustion Properties of Pure Metals in Solid Form . . . . . . . . . . . . . . . . . . B-29

B.9.1 Reference ............ ............ ............ ......... B-30

B.10 Extinguishing Agents for Metal Fires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-31

B.10.1 References ............ ............ ............ ........ B-32

B.11 Occupancy Classification and Use Groups . . . . . . . . . . . . . . . . . . . . . . . . . . B-32

B.11.1 Occupancy Classification ............ ............ ......... B-32

B.11.2 Special Use and Occupancy Requirements . . . . . . . . . . . . . . . . . . . B-34

B.11.3 Code Advances/Changes ............ ............ ......... B-34

B.11.4 References ............ ............ ............ ........ B-35

B.12 Building Limitations and Types of Construction . . . . . . . . . . . . . . . . . . . . . . B-36

B.12.1 Types of Construction ............ ............ ............ B-36

B.12.2 Five Construction Types ............ ............ .......... B-37

B.12.3 Fire Resistance Ratings ............ ............ .......... B-38

B.12.4 Reference ............ ............ ............ ......... B-38

B.13 Deep-Seated Fires in Class A Solid Materials . . . . . . . . . . . . . . . . . . . . . . . B-39

B.13.1 General Information ............ ............ ............ . B-39

B.13.2 Deep-Seated Cable Fires ............ ............ ......... B-40

B.13.3 Deep-Seated Charcoal Fires ............ ............ ....... B-40

B.13.4 References ............ ............ ............ ........ B-40

B.14 Special Hazard Gaseous Fire Extinguishing Agents . . . . . . . . . . . . . . . . . . B-41

B.14.1 Introduction ............ ............ ............ ........ B-41

B.14.2 Halogenated Agent Extinguishing Systems . . . . . . . . . . . . . . . . . . . B-41

B.14.3 Carbon Dioxide Fire Extinguishing Systems . . . . . . . . . . . . . . . . . . . B-53

B.14.4 References ............ ............ ............ ........ B-41

B.15 Dry Chemical Extinguishing Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-55

B.15.1 Hazards Associated with Dry Chemicals . . . . . . . . . . . . . . . . . . . . . B-57

B.15.2 References ............ ............ ............ ........ B-57

B.16 Fire Protection Using Foam ............ ............ ............ . B-58

B.16.1 Properties of Foam ............ ............ ............ . . B-59

B.16.2 Hazards Associated with Foam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-60

B.16.3 Delivery Systems for Foam ............ ............ ........ B-60

B.16.4 Application of Foam ............ ............ ............ . B-61

B.16.5 Types of Foam ............ ............ ............ ..... B-62

B.16.6 References ............ ............ ............ ........ B-65

B.16.7 Additional Reading ............ ............ ............ . . B-65
xvii

Appendices (continued)

B.17 Harmful Properties of Toxic Gases Found in Fires . . . . . . . . . . . . . . . . . . . . B-66

B.17.1 Introduction ............ ............ ............ ........ B-66

B.17.2 Smoke and Toxic Gases ............ ............ .......... B-67

B.17.3 Toxicity Data ............ ............ ............ ....... B-69

B.17.4 References ............ ............ ............ ........ B-71

B.18 Effects of Decomposition Products of Halogenated Fire Extinguishing Agents . . B-72

B.18.1 Introduction ............ ............ ............ ........ B-72

B.18.2 Toxicity of Decomposition Products

of Halogenated Fire Suppression Agents . . . . . . . . . . . . . . . . . . . . . B-73

B.18.3 Physical Properties of Halon 1301 . . . . . . . . . . . . . . . . . . . . . . . . . . B-75

B.18.4 Physical Properties of Halon 1211 . . . . . . . . . . . . . . . . . . . . . . . . . . B-76

B.18.5 References ............ ............ ............ ........ B-77

B.19 An Introduction to Computer Fire Models . . . . . . . . . . . . . . . . . . . . . . . . . . . B-78

B.19.1 Introduction ............ ............ ............ ........ B-78

B.19.2 Categories of Computer Fire Model . . . . . . . . . . . . . . . . . . . . . . . . . B-79

B.19.3 Limitations and Uncertainties Associated with Computer Fire Modeling B-84

B.19.4 Fire Models ............ ............ ............ ........ B-85

B.19.5 References ............ ............ ............ ........ B-89

B.19.6 Additional Readings ............ ............ ............ . B-89

C. Sources of Fire ............ ............ ............ ............ ...... C-1

C.1 Heat Sources ............ ............ ............ ............ . C-1

C.2 Incident Heat ............ ............ ............ ............ . . C-3

C.3 Target Fuel ............ ............ ............ ............ ... C-4

C.4 Flame/Heat Growth ............ ............ ............ ......... C-5

C.5 Fire Resistance ............ ............ ............ ............ C-6

C.6 Fire Resistance/Endurance Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-8

C.7 Fire Test Standards ............ ............ ............ ....... C-15

D. NRC Documents Related to Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1

D.1 Code of Federal Regulations Related to Nuclear Regulatory Commission

Fire Protection ............ ............ ............ ............ . D-1

D.2 Branch Technical Positions Related to Fire Protection . . . . . . . . . . . . . . . . . . D-2

D.3 NRC Regulatory Guides Related to Fire Protection . . . . . . . . . . . . . . . . . . . . D-3

D.4 NRC Generic Communications Related to Fire Protection . . . . . . . . . . . . . . . D-5

D.4.1 NRC Administrative Letters Related to Fire Protection . . . . . . . . . . . . D-5

D.4.2 NRC Bulletins Related to Fire Protection . . . . . . . . . . . . . . . . . . . . . . D-6

D.4.3 NRC Circulars Related to Fire Protection . . . . . . . . . . . . . . . . . . . . . . D-7

D.4.4 NRC Generic Letters Related to Fire Protection . . . . . . . . . . . . . . . . . D-8

D.4.5 NRC Information Notices Related to Fire Protection . . . . . . . . . . . . . D-10

D.4.6 NRC Regulatory Issue Summaries Related to Fire Protection . . . . . D-16

D.5 Commission (SECY) Papers Related to Fire Protection . . . . . . . . . . . . . . . . D-17

D.6 NRC Preliminary Notifications Related to Fire Incidents . . . . . . . . . . . . . . . . D-21

D.7 NRC Miscellaneous Documents Related to Fire Protection . . . . . . . . . . . . . D-24

D.8 NRR Staff Presentations and Publications Related to Fire Protection . . . . . D-27
xviii

Appendices (continued)

D.9 NRC Technical Reports in the NUREG Series Related to Nuclear Power Plant

Fire Protection Engineering Research and Development (R&D) . . . . . . . . . D-28

D.10 Safety Evaluation Reports Related to License Renewal 

for Operating Nuclear Power Plants ............ ............ ....... D-45

D.11 National Fire Protection Association (NFPA) Codes and Standards 

for Nuclear Facilities ............ ............ ............ ....... D-46

E. Current National Fire Protection Association (NFPA) Codes and Standards . . . . . . . E-1

F. Glossary of Fire Protection Terms ............ ............ ............ ... F-1

G. Abbreviations Used in Fire Protection Engineering . . . . . . . . . . . . . . . . . . . . . . . . . . G-1

H. Selected U.S. Commercial Nuclear Power Plant Fire Incidents . . . . . . . . . . . . . . . . . H-1

H.1 Introduction ............ ............ ............ ............ ... H-1

H.2 San Onofre Nuclear Generating Station, Unit 1, 

February 7 and March 12, 1968 ............ ............ ........... H-6

H.3 Browns Ferry Nuclear Power Plant, Unit 1, March 22, 1975 . . . . . . . . . . . . . H-8

H.4 North Anna Power Station, Unit 2, July 3, 1981 . . . . . . . . . . . . . . . . . . . . . . H-11

H.5 Rancho Seco, March 19, 1984 ............ ............ ........... H-12

H.6 Waterford Steam Electric Station, Unit 3, June 26, 1985 . . . . . . . . . . . . . . . H-13

H.7 Fort St. Vrain Nuclear Generating Station, October 2, 1987 . . . . . . . . . . . . . H-14

H.8 Oconee Nuclear Station, Unit 1, January 3, 1989 . . . . . . . . . . . . . . . . . . . . . H-15

H.9 H.B. Robinson Steam Electric Plant, Unit 2, January 7, 1989 . . . . . . . . . . . H-16

H.10 Calvert Cliffs Nuclear Power Plant, Unit 2, March 1, 1989 . . . . . . . . . . . . . . H-17

H.11 Shearon Harris Nuclear Power Plant, October 9, 1989 . . . . . . . . . . . . . . . . H-18

H.12 Salem Generating Station Unit 2, November 9, 1991 . . . . . . . . . . . . . . . . . . H-20

H.13 Waterford Steam Electric Station Unit 3, June 10, 1995 . . . . . . . . . . . . . . . . H-21

H.14 Palo Verde Nuclear Generating Station Unit 2, April 4, 1996 . . . . . . . . . . . . H-24

H.15 San Onofre Nuclear Generating Station, Unit 3, February 3, 2001 . . . . . . . H-26

H.16 Point Beach Nuclear Plant, Unit 1, April 24, 2001 . . . . . . . . . . . . . . . . . . . . H-29

H.17 Prairie Island Nuclear Generating Plant, Unit 1, August 3, 2001 . . . . . . . . . H-30

H.18 Fort Calhoun Station, Unit 1, December 19, 2001 . . . . . . . . . . . . . . . . . . . . H-32
xix

Appendices (continued)

I. Mathematics Review and System of Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-1

I.1 Mathematics Review ............ ............ ............ ......... I-1

I.1.1 Units of Measurement ............ ............ ............ . . I-1

I.1.2 Math Functions ............ ............ ............ ....... I-6

I.1.3 Solving Equations ............ ............ ............ ..... I-8

I.1.4 Caution with T Conversions ............ ............ ....... I-10

I.1.5 Miscellaneous Information ............ ............ ......... I-11

I.1.6 Reference ............ ............ ............ .......... I-12

I.2 Notation Conventions ............ ............ ............ ....... I-13

I.2.1 References ............ ............ ............ ......... I-13

I.3 System of Units ............ ............ ............ ............ I-14

I.3.1 Length, Area, and Volume Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-14

I.3.2 Mass and Density Units ............ ............ ........... I-14

I.3.3 Time Units ............ ............ ............ .......... I-14

I.3.4 Force and Pressure Units ............ ............ .......... I-15

I.3.5 Energy Units ............ ............ ............ ........ I-15

I.3.6 Power Units ............ ............ ............ ......... I-15

I.3.7 Temperature Units ............ ............ ............ ... I-16

I.3.8 References ............ ............ ............ ......... I-16

I.4 Physical Constants for General Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-17

I.4.1 References ............ ............ ............ ......... I-17

J. Practice Problems and Solutions ............ ............ ............ .... J-1
xx

Figures

Page

1-1 Physical Process of Combustion and Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

1-2 The Fire Triangle ............ ............ ............ ............ .... 1-5

2-1 Typical Stages of Fire Development ............ ............ ............ . . 2-2

2-2 Stages of Compartment Fire ............ ............ ............ ........ 2-2

2-3 Types of Mechanical Ventilation Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

2-4 Smoke Filling In a Compartment Fire ............ ............ ............ 2-15

2-5 General Representation of Heat Release Rate Histories for a Fuel Package . . . . . 2-18

3-1 A Simple Design Fire Curve ............ ............ ............ ........ 3-2

3-2 Dynamic Features of a Pool Fire ............ ............ ............ .... 3-7

3-3 Temperature Distribution in the Flame of a Burning Candle . . . . . . . . . . . . . . . . . . . . 3-9

3-4 Diffusion Flame ............ ............ ............ ............ ..... 3-10

3-5 Premixed Flame ............ ............ ............ ............ .... 3-10

3-6 Laminar Diffusion Flame ............ ............ ............ .......... 3-10

3-7 Turbulent Premixed Flames ............ ............ ............ ....... 3-11

3-8 Flame Extensions with a Free-Burning Flame and Under a Smooth Ceiling . . . . . . 3-13

3-9 Characteristics of Flame Height Fluctuations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-16

4-1 Wall Fire Flame Configuration ............ ............ ............ ...... 4-3

4-2 Line Fire Flame Against a Wall ............ ............ ............ ...... 4-3

4-3 Corner Fire Flame Configuration ............ ............ ............ .... 4-4

5-1 Radiant Heat Flux from a Pool Fire to a Floor-Based Target Fuel (Point Source Model) . . 5-4

5-2 Solid Flame Radiation Model with No Wind and Target at Ground Level . . . . . . . . . . 5-5

5-3 Solid Flame Radiation Model with No Wind and Target Above Ground . . . . . . . . . . . 5-6

5-4 Cylindrical Flame Shape Configuration Factor Geometry for Vertical and Horizontal

Targets at Ground Level with No Wind ............ ............ ............ 5-8

5-5 Cylindrical Flame Shape Configuration Factor Geometry for Vertical and Horizontal

Targets Above Ground with No Wind ............ ............ ............ . 5-8

5-6 Solid Flame Radiation Model in Presence of Wind and Target Above Ground Level 5-11

5-7 Solid Flame Radiation Model in Presence of Wind and Target at Ground Level . . . 5-11

6-1 Ignition Processes for Liquid and Solid Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

6-2 External Radiation to a Solid Target from a Flame or Hot Surface

at Evaluated Temperature ............ ............ ............ ......... 6-2

9-1 A Buoyant Turbulent Plume Showing Air Entrainment . . . . . . . . . . . . . . . . . . . . . . . . 9-1

9-2 Three Zones of the Axisymmetric Buoyant Fire Plume . . . . . . . . . . . . . . . . . . . . . . . 9-3

9-3 Fire Plume with Virtual Origin ............ ............ ............ ....... 9-5
xxi

Figures (continued)

10-1 Heat Transfer Characteristics of the Heat-Sensitive Element of Sprinkler . . . . . . . . 10-4

10-2 Representative Arrangement of a Solder-Type Link-and-Lever Automatic Sprinkler 10-5

10-3 Ceiling Jet Flow Beneath an Unconfined Ceiling and Sprinkler Activation . . . . . . . 10-11

11-1 Qualitative Relationship Between Time and Damage for Different Speeds of Fire

Development and Average Detection, Reaction, and Fire Fighting . . . . . . . . . . . . . . 11-2

11-2 Illustration of the Photoelectric Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-4

11-3 Illustration of the Ionization Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-4

12-1 Ceiling Jet Flow Beneath an Unconfined Ceiling Showing a Heat Detector . . . . . . . 12-9

13-1 Flashover and Post-Flashover Compartment Fire . . . . . . . . . . . . . . . . . . . . . . . . . . 13-2

14-1 Overpressure Generated at a Fixed Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-1

15-1 Pressure Peaks of an Explosion Inside a Building . . . . . . . . . . . . . . . . . . . . . . . . . . 15-5

15-2 Propagation of Explosion Flame ............ ............ ............ .... 15-6

15-3 Ideal Blast Wave Overpressure vs. Scaled Distance . . . . . . . . . . . . . . . . . . . . . . . 15-11

16-1 Flammability Limits of Hydrogen in Air Diluted with Carbon Dioxide and Nitrogen . 16-3

16-2 Flammability Limits of Hydrogen in Air-Steam Mixtures . . . . . . . . . . . . . . . . . . . . . . 16-3

16-3 Spark Ignition Energies for Dry Hydrogen-Air Mixtures . . . . . . . . . . . . . . . . . . . . . . 16-4

16-4 Typical Flammability Diagram ............ ............ ............ ...... 16-5

17-1 Standard Time-Temperature Curve (ASTM E119) . . . . . . . . . . . . . . . . . . . . . . . . . . 17-1

17-2 Typical Methods of Protecting Various Structural Steel Elements from Fire . . . . . . 17-4

17-3 Encasement of a Steel Beam by Monolithic Casting of Concrete Around the Beam 17-9

17-4 Spray-On Mineral Fibers and Noncombustible Protective Coatings . . . . . . . . . . . . . 17-9

17-5 Sections of Unprotected Steel Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-11

17-6 Heated Perimeters for Common Column and Beam Shapes . . . . . . . . . . . . . . . . . 17-12

17-7 Concrete-Protected Structural Steel Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-15

A-1 Basic Electrical Cable Construction — Common Single- and Multi-Conductor 

Arrangements ............ ............ ............ ............ ....... A-4

A-2 Thermoplastic Insulated Cable Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-7

A-3 Thermoset Insulated Cable Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-8

A-4 Raw Time to Damage Chart for Thermoset XLPE Cables . . . . . . . . . . . . . . . . . . . . A-15

A-5 Time to Damage Plot for Thermoset Cables with Linear Regression Curve . . . . . . A-16

A-6 Raw Time to Damage Plot for Thermoplastic PE Cables . . . . . . . . . . . . . . . . . . . . . A-17

A-7 Time to Damage Plot for Thermoplastic Cables with Linear Regression Curve . . . . A-18
xxii

Figures (continued)

B.1-1 Fire Growth of t Fitted to Data ............ ............ ............ ....

2 B-2

B.1-2 Growth Rate Curves for t Fire ............ ............ ............ .....

2 B-4

B.1-3 Comparison of t Heat Release Rate with Full-Scale Free-Burn Heat Release Rate .

2 B-5

B.1-4 Relation of t Heat Release Rate to Some Fire Tests . . . . . . . . . . . . . . . . . . . . . . .

2 B-5

B.1-5 Comparison of t Heat Release Rate with Full-Scale Furniture Heat Release Rate . .

2 B-6

B.1-6 Three-Sided Work Station Heat Release Rate Curve Compared With t Curves . .

2 B-8

B.1-7 Heat Release Rate Curve for Idle Pallets Compared with t Curves . . . . . . . . . . . .

2 B-9

B.1-8 Heat Release Rate for Stacked Box Fires Compared with t Curves . . . . . . . . . .

2 B-10

B.14-1 Indication of Deep-Seated Fire and Reignition of Cables, Test # 60,

IEEE-383-Qualified Cables, Horizontal Trays, 4-Minute Halon Soak

Acceptor Tray Center Temperature ............ ............ ............ B-44

B.14-2 Soaking Time vs. Halon 1301 Concentration for Deep-Seated and Surface Fires B-45
xxiii

Tables

Page

1-1 Common Combustible and Hazardous Materials in NPPs . . . . . . . . . . . . . . . . . . . . . 1-6

2-1 Temperature Conversions ............ ............ ............ ......... 2-7

2-2 Critical Temperatures for Different Exposure Conditions and Effects on Humans . . . 2-7

2-3 Thermal Properties of Compartment Enclosing Surface Materials . . . . . . . . . . . . . . 2-11

2-4 Measured Heat Release Rate Data for Cable Jacketing Material . . . . . . . . . . . . . . 2-20

2-5 Measured Heat Release Rate Data for Electrical Cabinets . . . . . . . . . . . . . . . . . . . 2-20

2-6 Measured Heat Release Rate Data for Transient Combustible Materials

(Flammable/Combustible Liquids) ............ ............ ............ . . 2-21

2-7 Measured Heat Release Rate Data for Transient Combustible Materials (Trash) . . 2-21

2-8 Measured Heat Release Rate Data for Transient Combustible Materials

(Plywood and Wood Pallet) ............ ............ ............ ....... 2-22

2-9 Ignition Thresholds (Pilotless within 30 seconds) . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22

2-10 Thermal Effects on Electronics ............ ............ ............ ..... 2-22

3-1 Rough Measure of Heat Generated from Various Sources . . . . . . . . . . . . . . . . . . . . 3-2

3-2 Large-Pool Fire Burning Rate Data ............ ............ ............ . . 3-4

3-3 Pool Fire Burning Modes ............ ............ ............ .......... 3-5

3-4 Burning Rates of Some Combustible Materials Found in Nuclear Power Plants . . . . 3-6

3-5 Flame Temperatures of Selected Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13

3-6 Adiabatic Flame Temperatures of Selected Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15

6-1 Typical Heat Fluxes From Various Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

6-2 Typical Ignition Times of Thick Solid Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4

6-3 Critical Heat Flux and Thermal Response Parameters of Selected Materials . . . . . . 6-6

6-4 Ignition Temperature and Thermal Properties of Materials . . . . . . . . . . . . . . . . . . . . 6-7

6-5 Ignition and Flame Spread Properties of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10

6-6 Ignition and Flame Spread Properties of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . 6-12

7-1 Bench-Scale HRR of a Cable Tray Fire ............ ............ ........... 7-4

7-2 Thermoplastic vs. Thermoset Cables ............ ............ ............ . 7-5

8-1 Thermal Properties of Solid Combustible Materials . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3

10-1 Temperature Rating, Classification, and Color Coding of Automatic Sprinklers . . . . 10-6

10 activation -2 Generic Sprinkler Temperature Rating (T ) . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-7

10-3 Generic Sprinkler Response Time Index (RTI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-8

12-1 Time Constant of Any Listed Detector ............ ............ ........... 12-7

12-2 Detector Response Time Index of Any Listed Detector . . . . . . . . . . . . . . . . . . . . . . 12-8
xxiv

Tables (continued)

15-1 Estimated Damage Attributable to Explosive Overpressure . . . . . . . . . . . . . . . . . . . 15-7

15-2 Heat of Combustion, Ignition Temperature, and Adiabatic Flame Temperature 

of Flammable Gases ............ ............ ............ ............ 15-10

15-3 Pressure Effects on Humans ............ ............ ............ ..... 15-12

15-4 Typical Failure Pressures of Some Building Elements . . . . . . . . . . . . . . . . . . . . . . 15-13

16-1 Hydrogen Flammability Limits in Air at Room Temperature . . . . . . . . . . . . . . . . . . . 16-2

16-2 Float Current Demand for Stationary Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-8

16-3 Mixing Efficiency for Various Ventilation Arrangements . . . . . . . . . . . . . . . . . . . . . 16-10

17-1 Standard Time-Temperature Curve Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-2

17-2 Temperature Endpoint Criteria for Structural Members . . . . . . . . . . . . . . . . . . . . . . 17-6

17-3 Typical Fire Resistance of Walls ............ ............ ............ .... 17-7

17-4 Resultant Emissivity for Different Types of Construction . . . . . . . . . . . . . . . . . . . . 17-19

17-5 Spreadsheet Calculation for the Temperature of Steel Sections . . . . . . . . . . . . . . 17-20

17-6 Thermal Properties of Insulation Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-22

18-1 Proportionality Constants for Visibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-3

18-2 Specific Extinction Coefficient for Visibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-3

18-3 Smoke Particulate Yield ............ ............ ............ .......... 18-4

A-1 Designation of Electrical Rated Voltages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3

A-2 Failure Time-Temperature Relationship for Thermoset Cables . . . . . . . . . . . . . . . . A-16

A-3 Failure Time-Temperature Relationship for Thermoplastic Cables . . . . . . . . . . . . . A-18

A-4 Estimated Time to Damage for Radiant Heating Exposures for Thermoset Cables . A-19

A-5 Estimated Time to Damage for Radiant Heating Exposures for Thermoplastic Cables . . A-19

B.1-1 Summary of t Fire Parameters ............ ............ ............ .....

2 B-3

B.1-2 Maximum Heat Release Rates of Warehouse Materials . . . . . . . . . . . . . . . . . . . . . . B-6

B.2-1 Corresponding Elements of Hydraulic and Electrical Systems . . . . . . . . . . . . . . . . . B-11

B.5-1 Fire Classes with Extinguishing Agents ............ ............ .......... B-16

B.6-1 Flammable Liquid Classifications ............ ............ ............ ... B-17

B.6-2 Combustible Liquid Classifications ............ ............ ............ . . B-18

B.6-3 Flash Points of Flammable and Combustible Liquids . . . . . . . . . . . . . . . . . . . . . . . . B-19

B.6-4 Maximum Allowable Size of Containers and Portable Tanks

for Flammable and Combustible Liquids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-20

B.6-5 Hazardous Material Classification ............ ............ ............ . . B-22

B.9-1 Melting, Boiling, and Ignition Temperatures of Pure Metals in Solid Form . . . . . . . B-30

B.10-1 Extinguishing Agents for Metal Fires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-31
xxv

Tables (continued)

B.12-1 Construction Classifications of the Model Codes and NFPA 220 . . . . . . . . . . . . . . . B-38

B.14-1 Halogenated Hydrocarbons Commonly Used for Fire Protection . . . . . . . . . . . . . . . B-42

B.15-1 Dry Chemical Agents ............ ............ ............ ............ B-55

B.17-1 Toxicity Data ............ ............ ............ ............ ....... B-69

B.18-1 Approximate Lethal Concentrations (ALCs) for Predominant 

Halon 1301 and Halon 1211 Decomposition Products . . . . . . . . . . . . . . . . . . . . . . . B-73

B.18-2 Concentration of Hazardous Gases Attributable to Decomposition of Halon 1301

in Industrial Baghouse Fire Situation ............ ............ ............ B-74

B.18-3 Halon 1301 Decomposition Produced by an n-Heptane Fires . . . . . . . . . . . . . . . . . B-76

B.18-4 Selected Properties of Halon 1301, 1211, and 2402 . . . . . . . . . . . . . . . . . . . . . . . . B-76

B.19-1 Computer Fire Models ............ ............ ............ ........... B-85

C.1-1 Common Engineering Terms Related to Heat Sources . . . . . . . . . . . . . . . . . . . . . . . C-2

C.2-1 Incident Heat ............ ............ ............ ............ ........ C-3

C.3-1 Target Fuel ............ ............ ............ ............ ......... C-4

C.4-1 Flame/Heat Growth ............ ............ ............ ............ ... C-5

C.5-1 Common Engineering Terms Related to Fire Severity . . . . . . . . . . . . . . . . . . . . . . . . C-6

C.5-2 Common Engineering Terms Related to Fire Performance . . . . . . . . . . . . . . . . . . . . C-7

C.6-1 Fire-Resistance Test Standards for Building Materials . . . . . . . . . . . . . . . . . . . . . . . C-12

C.6-2 Fire-Resistance Test Standards for Aerosol and Liquid Paints . . . . . . . . . . . . . . . . C-13

C.6-3 Fire-Resistance Test Standards for Plastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-14

D.3-1 NRC Regulatory Guides Related to Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . . . D-3

D.4-1 NRC Administrative Letters Related to Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . D-5

D.4-2 NRC Bulletins Related to Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-6

D.4-3 NRC Circulars Related to Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-7

D.4-4 NRC Generic Letters Related to Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-8

D.4-5 NRC Information Notices Related to Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . D-10

D.4-6 NRC Regulatory Issue Summaries Related to Fire Protection . . . . . . . . . . . . . . . . . D-16

D.5-1 Commission (SECY) Papers Related to Fire Protection . . . . . . . . . . . . . . . . . . . . . . D-18

D.6-1 Preliminary Notifications Related to Fire Incidents . . . . . . . . . . . . . . . . . . . . . . . . . . D-21

E.1-1 NFPA Codes and Standards ............ ............ ............ ....... E-1

H.1-1 Summary of Selected U.S. Commercial Nuclear Power Plant Fire Incidents . . . . . . . H-2

I.1-1 Basic Units ............ ............ ............ ............ .......... I-1

I.1-2 Derived Units ............ ............ ............ ............ ........ I-2

I.1-3 SI Prefixes ............ ............ ............ ............ .......... I-3

I.1-4 Scientific Notations, Prefixes, and Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I-4

I.1-5 Selected Unit Conversions ............ ............ ............ .......... I-5

I.4-1 Values of Constants for General Use ............ ............ ............ . I-17
xxvi
xxvii

LIST OF FIRE DYNAMICS TOOLS

The NRC’s Office of Nuclear Reactor Regulation (NRR) developed the fire dynamics tools

(FDT ) using commercially available software (Microsoft Excel 2000). s ®

FDT Chapter and Related Calculation Method(s) s

02.1_Temperature_NV.xls

Chapter 2. Predicting Hot Gas Layer Temperature

and Smoke Layer Height in a Room Fire

with Natural Ventilation

Method of McCaffrey, Quintiere, and Harkleroad (MQH)

• Compartment with Thermally Thick/Thin Boundaries

02.2_Temperature_FV.xls

Chapter 2. Predicting Hot Gas Layer Temperature

in a Room Fire with Forced Ventilation

Method of Foote, Pagni, and Alvares (FPA)

• Compartment with Thermally Thick/Thin Boundaries

Method of Deal and Beyler

• Compartment with Thermally Thick/Thin Boundaries

02.3_Temperature_CC.xls Chapter 2. Predicting Hot Gas Layer Temperature in a Room

Fire with Door Closed

Compartment has Sufficient Leaks

to Prevent Pressure Buildup; Leakage is Ignored

Method of Beyler

03_HRR_Flame_Height_Burning_

Duration_Calculation.xls

Chapter 3. Estimating Burning Characteristics

of Liquid Pool Fire, Heat Release Rate,

Burning Duration and Flame Height

04_Flame_Height_Calculations.xls Chapter 4. Estimating Wall Fire Flame Height,

Line Fire Flame Height Against the Wall,

and Corner Fire Flame Height
xxviii

LIST OF FIRE DYNAMICS TOOLS (continued)

FDT Chapter and Related Calculation Method s

05.1_Heat_Flux_Calculations_Wind_

Free.xls

05.2_Heat_Flux_Calculations_Wind.xls

05.3_Thermal_Radiation_From_

Hydrocarbon_Fireballs.xls

Chapter 5. Estimating Radiant Heat Flux from Fire

to a Target Fuel

Wind-Free Condition

• Point Source Radiation Model (Target at Ground Level)

• Solid Flame Radiation Model (Target at Ground Level)

• Solid Flame Radiation Model

(Target Above Ground Level)

Presence of Wind

• Solid Flame Radiation Model (Target at Ground Level)

• Solid Flame Radiation Model (Target Above Ground Level)

Estimating Thermal Radiation from Hydrocarbon Fireballs

06_Ignition_Time_Calculations.xls Chapter 6. Estimating the Ignition Time of a Target Fuel

Exposed to a Constant Radiative Heat Flux

• Method of Estimating Piloted Ignition Time

of Solid Materials Under Radiant Exposures

Method of (1) Mikkola and Wichman,

(2) Quintiere and Harkleroad, and (3) Janssens

• Method of Estimating Piloted Ignition Time of Solid

Materials Under Radiant Exposures

Method of Toal, Silcock and Shields

• Method of Estimating Piloted Ignition Time of Solid

Materials Under Radiant Exposures

Method of Tewarson

07_Cable_HRR_Calculations.xls Chapter 7. Estimating Full-Scale Heat Release Rate

of a Cable Tray Fire

08_Burning_Duration_Soild.xls Chapter 8. Estimating Burning Duration of Solid

Combustibles

09_Plume_Temperature_Calculations.xls Chapter 9. Estimating Centerline Temperature

of a Buoyant Fire Plume
xxix

LIST OF FIRE DYNAMICS TOOLS (continued)

FDT Chapter and Related Calculation Method s

10_Detector_Activation_Time.xls Estimating Detector Response Time

Chapter 10. Estimating Sprinkler Response Time

Chapter 11. Estimating Smoke Detector Response Time

Chapter 12. Estimating Heat Detector Response Time

13_Compartment_ Flashover_

Calculations.xls

Chapter 13. Predicting Compartment Flashover

• Compartment Post-Flashover Temperature:

Method of Law

• Minimum Heat Release Rate

Required to Compartment Flashover:

Method of (1) McCaffrey, Quintiere, and Harkleroad

(MQH); (2) Babrauskas; and (3) Thomas

14_Compartment_Over_Pressure_

Calculations.xls

Chapter 14. Estimating Pressure Rise

Attributable to a Fire in a Closed Compartment

15_Explosion_Claculations.xls Chapter 15. Estimating the Pressure Increase

and Explosive Energy Release

Associated with Explosions

16_Battery_Room_Flammable_Gas_

Conc.xls

Chapter 16. Calculating the Rate of Hydrogen Gas

Generation in Battery Rooms

• Method of Estimating Hydrogen Gas Generation

Rate in Battery Rooms

• Method of Estimating Flammable Gas and Vapor

Concentration Buildup in Enclosed Spaces

• Method of Estimating Flammable Gas and Vapor

Concentration Buildup Time in Enclosed Spaces
xxx

LIST OF FIRE DYNAMICS TOOLS (continued)

FDT Chapter and Related Calculation Method s

17.1_FR_Beams_Columns_

Substitution_Correlation.xls

17.2_FR_Beams_Columns_Quasi_

Steady_State_Spray_Insulated.xls

17.3_FR_Beams_Columns_Quasi_

Steady_State_Board_Insulated.xls

17.4_FR_Beams_Columns_Quasi_

Steady_State_Uninsulated.xls

Chapter 17. Calculating the Fire Resistance

of Structural Steel Members

• Empirical Correlations

• Beam Substitution Correlation (Spray-Applied Materials)

• Column Substitution Correlation (Spray-Applied Materials)

• Heat Transfer Analysis using Numerical Methods

Protected Steel Beams and Columns (Spray-Applied)

• Heat Transfer Analysis using Numerical Methods

Protected Steel Beams and Columns (Board Materials)

• Heat Transfer Analysis using Numerical Methods

Unprotected Steel Beams and Columns

18_Visibility_Through_Smoke.xls Chapter 18. Estimating Visibility Through Smoke
xxxi

DISCLAIMER

The calculation methods presented in this NUREG-series report and programmed in the Fire

Dynamics Tools (FDT ) spreadsheets include scientific calculations, as well as material physical s

and thermal properties relevant to fire hazard analyses. Each spreadsheet on the CD-ROM has

been protected and secured to avoid calculation errors attributable to invalid entries in the cell(s).

Although each calculation in each spreadsheet has been verified with the results of hand

calculations, there is no absolute guarantee of the accuracy of these calculations.

The first-time analyst should read the text in this report in its entirety before making an analysis.

Most of the equations and correlations in the spreadsheets are simple mathematical expressions

commonly used in fire protection engineering. The mathematical expressions are not limited,

however, and they sometimes give physically impossible values. Where we have encountered this

problem, or where a value exceeds known limits, we have added red warning flags to the

spreadsheets. For example a red flag appears when an equation increases the hot gas layer

temperature as a result of a fire that goes well beyond those that are physically possible.

Finally, with respect to any errors, omissions, or oversights that may still exist in the text, we are

of one mind. Any shortcomings are the results of something the other one of us did or did not do. No one

else can share them.

The publication of this NUREG-series report completes the initial effort by the NRC’s Office of

Nuclear Reactor Regulation to produce an Introduction to Fire Dynamics for NRC Inspectors.

Future updates or corrections, or new FDT spreadsheets will be posted on the NRC’s public

s

Web site in the Fire Protection section of the Reactor Operating Experience page at 

http://www.nrc.gov/reactors/operating/ops-experience/fire-protection.html.

To offer any questions, comments, or suggestions, or to report an error in the NUREG or FDT ,

s

please send an email message to NXI@nrc.gov or MXS3@nrc.gov, or write to:

Naeem Iqbal

Office of Nuclear Reactor Regulation

U.S. Nuclear Regulatory Commission

Mail Stop O11-A11

Washington, DC 20555-0001

or

Mark Henry Salley

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

Mail Stop T10-E50

Washington, DC 20555-0001
xxxii
xxxiii

THE AUTHORS

Naeem Iqbal

Naeem Iqbal is a Fire Protection Engineer in the NRC’s Office of Nuclear Reactor Regulation

(NRR). He holds a Master of Science degree in fire protection engineering from the University of

Maryland at College Park and a Bachelor of Science degree in mechanical engineering from NED

University of Engineering and Technology in Pakistan. Mr. Iqbal is a member of the Society of Fire

Protection Engineers (SFPE); National Fire Protection Association (NFPA); American Society of

Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE); and International Association

of Fire Safety Science (IAFSS).

Mr. Iqbal has been actively involved in fire hazard analysis, computer and mathematical fire

modeling, smoke spread and fire growth, fire code review and compliance, and fire risk assessment

projects for U.S. commercial nuclear power plants. He also reviews and prepares safety evaluation

reports for power reactors. Mr. Iqbal is currently involved in preparing safety evaluation reports to

support renewal of licenses for extended operation of the Nation’s operating nuclear power plants

under Title 10, Part 54, of the Code of Federal Regulations (10 CFR Part 54). He has also been

involved in research and development projects in fire protection engineering, with a particular focus

on fundamental and applied aspects of fire safety science, engineering, and technology.

In addition, Mr. Iqbal has authored several publications and technical reports on flame spread,

burning rate, fire growth on materials, and fire hazard analysis.

Prior to joining the NRC, Mr. Iqbal worked for Hughes Associates, Inc., a leading engineering

consulting firm specializing in engineering design, research and development, and advanced

technology related to fire protection engineering. There, he was responsible for performing

technical studies of a wide range of fire protection problems, as well as fire hazard and risk analysis

of unusual and unique situations in commercial and industrial facilities and Department of Energy

(DOE) nuclear processing facilities problems involving model building codes and fire codes that fail

to adequately address a particular situation.

Mark Henry Salley, P.E.

Mark Henry Salley currently serves as Fire Research Team Leader in the NRC’s Office of Nuclear

Regulatory Research (RES); however, he prepared much of this publication as a Fire Protection

Engineer in NRR. Mr. Salley holds Master and Bachelor of Science degrees in fire protection

engineering, both from the University of Maryland at College Park. He is a registered professional

engineer in fire protection engineering and a member of the NFPA, SFPE, and American Nuclear

Society (ANS).

Prior to joining the NRC, Mr. Salley was the Corporate Fire Protection Engineer for the Tennessee

Valley Authority Nuclear (TVAN) program. There, he was responsible for the overall TVAN Fire

Protection and Fire Safe-Shutdown Program (under 10 CFR Appendix R). Mr. Salley worked on

the restart of Sequoyah Nuclear Plant, Units 1 and 2, as well as Browns Ferry Nuclear Plant,

Units 2 and 3. He also played an integral role in the completion of construction, licensing, and

startup of Watts Bar Nuclear Plant, Unit 1.
xxxiv

Mr. Salley has also served as a Principle Project Engineer for Parsons-Main Inc. in Charlotte, North

Carolina. There, he supported the restart of the K-reactor at the DOE Savannah River Site

and the site-wide fire protection upgrade.

Mr. Salley has an extensive background in fire protection engineering, including firefighting, design

engineering, fire testing, and analytical analysis. He has also authored papers in the area of fire

protection engineering.
xxxv

ACKNOWLEDGMENTS

The authors gratefully acknowledge Dr. Frederick Mowrer and the University of Maryland,

Department of Fire Protection Engineering. Both authors have attended Dr. Mowrer’s Advanced

Fire Modeling course (ENFP 625) as a part of their postgraduate studies, and the general concepts

used in creating and developing the FDT spreadsheets are similar to those taught by Dr. Mowrer. s

The authors also thank Mr. Sunil Weerakkody, the NRC Project Manager and Fire Protection

Section Chief who spearheaded this project. We also gratefully acknowledge the contributions of

our colleagues and managers at NRC Headquarters who supported us throughout this project, as

well as the NRC’s regional managers and fire protection inspectors who offered valuable

contributions, support, and suggestions. The regional inspectors also contributed valuable advice

during quarterly fire protection seminars to improve the quality of the FDT spreadsheets. s

We developed the final product with them in mind as the end users.

The authors also extend our thanks to Tanya Mensah and James Downs, Fire Protection Engineers

with NRR/DSSA/SPLB, as well as the NRR Nuclear Safety Interns (Matthew Yoder, Jason

Dreisbach, Joel Rivera-Oritz, and Alexander Velazquez-Lozada) who assisted us in preparing this

report and the FDT spreadsheets. We deeply appreciate their invaluable assistance. We also s

gratefully acknowledge George Hausman, a Reactor Inspector in Region III, for assisting in making

the FDT spreadsheets more user-friendly. We also extend special thanks to Ms. Paula Garrity, s

a Technical Editor with the Program Management, Policy Development and Analysis Staff of the

NRC’s Office of Nuclear Regulatory Research (RES), for providing editorial support, navigating us

through the formal requirements, and assisting us in setting the style and appearance of the text.

We are also indebted to Mr. Lionel Watkins and Ms. Monique King, two talented Visual Information

Specialists in the Information and Records Services Division, Publishing and Distribution Services

Branch, of the NRC’s Office of Chief Information Officer (OCIO), who designed the cover and many

of the graphics for this report. In addition, we greatly appreciate the support of Gary Lauffer

(Chief of the Publishing Services Branch), Guy Beltz, (the agency’s Printing Specialist), and

Linda Stevenson (the agency’s publications specialist), whose invaluable support and expertise

were critical to ensuring the quality of the published manuscript.

Our sincere thanks also go to Mr. Gerald Haynes, a Fire Protection Engineer, with the Bureau of

Alcohol, Tobacco, Firearms, and Explosives (ATF&E) in Washington, DC, who identified the

concept of spreadsheets used in the ATF&E fire and arson investigation program. The ATF&E’s

spreadsheets served as a conceptual model for the NRC’s effort. Mr. Haynes, Mr. Stephen Hill,

and numerous Certified Fire Inspectors (CFIs) at the ATF&E also provided valuable comments on

the development of the NRC’s spreadsheets.

Finally, the authors thank the NRC inspectors and external stakeholders who took the time

to provide comments, suggestions, and words of encouragement on the first draft of this document

when it was published in the Federal Register (Vol. 68, No. 140, Page 43400). The following pages

acknowledge these contributors.

Naeem Iqbal Mark Henry Salley
xxxvi

Internal Stakeholders

NRC Regional Inspectors

Region I:

Richard Barkley

Ram Bhatia

Christopher Cahill

Leonard Cheung

Eugene Cobey

Aniello DellaGreca

Harold Eichenholz

Roy Fuhrmeister

James Linville

Glenn Meyer

John Rogge

Larry Scholl

James Trapp

Richard Urban

Tracy Walker

David Werkheiser

Keith Young

Region II:

Charles Casto

Charles Ogle

Charles Payne

Reinaldo Rodriguez

Walter Rogers

Robert Schin

Caswell Smith

Necota Staples

McKenzie Thomas

Gerald Wiseman

Region III:

Sonia Burgess

Doris Chyu

Robert Daley

Zelig Falevits

Ronald Gardner

John Grobe

George Hausman

David Hills

Benny Jose

Ronald Langstaff

Julio Lara

Kenneth O’Brien

Michael Parker

Cynthia Pederson

Darrell Schrum

Region IV:

Lawrence Ellershaw

Paula Goldberg

Claude Johnson

Charles Marschall

John Mateychick

Timothy McConnell

William McNeill

Raymond Mullikin

Rebecca Nease

Neil O’Keefe

Charles Paulk

Troy Pruett

Linda Smith

Joseph Taylor

John Whittemore

NRC Headquarters

SPLB 

Fire Protection:

Richard Dipert

Daniel Frumkin

Raymond Gallucci

Alexander Klein

Paul Lain

Phillip Qualls

Robert Radlinski

NRR:

Suzanne Black

John Hannon

Michael Johnson

Peter Koltay

George Morris

Robert Perch

Mark Reinhart

See-Meng Wong

RES:

Monideep Dey

J.S. Hyslop

William Raughley

Nathan Siu

ACRS:

Dana Powers

Stephen Rosen

John Sieber

Graham Wallis

External Stakeholders (Significant Public Comments)

Rashid Abbas (TVA)

Vytenis (Vyto) Babrauskas, PhD

(Fire Science and Technology Inc.)

Nick Barilo (Bechtel Hanford, Inc.)

Thomas F. Barry, P.E. (Fireriskforum)

John Bryan, EdD, Professor Emeritus

(Fire Protection Eng., University of MD)

Brad Dolan (Robinson NPP PSA Engineer)

Tom Fernandez (DE Design, A&E)

Wayne D. Holmes, P.E., FSFPE

(HSB Professional Loss Control)

Morgan J. Hurley, P.E. (SFPE)

James R. Hutton, PE, CSP

(National Nuclear Security Administration)

David J. Icove, PhD, PE

(U.S. Tennessee Valley Authority Police)

Peter Jackman (International Fire Consultants, Ltd.)

Moonhak Jee

(KEPRI in Korea)

Francisco Joglar (SAIC)

Alex Marion (Nuclear Energy Institute)

Leong Poon

(Warrington Fire Research in Australia)

Deggary N. Priest (Omega Point Laboratories)

Robert Toth

(International Association of Arson Investigators)

Woody Walker (Arkansas Nuclear One)

Ulf Wickström, SP (Sweden)
NRC Inspection Manual, Chapter 0609F, Appendix F, “Determining Potential Risk Significance *

of Fire Protection and Post-Fire Safe Shutdown Inspection Findings,” February 27, 2001.

NRC Inspection Manual, Chapter 0609F, Appendix F, Section F.5, “Fire Protection Risk **

Significance Screening Methodology—Phase 2, Step 4: Integrated Assessment of DID Findings

(Excluding SSD) and Fire Ignition Frequency,” February 27, 2001.

xxxvii

EXECUTIVE SUMMARY

The U.S. Nuclear Regulatory Commission (NRC), Office of Nuclear Reactor Regulation (NRR),

Division of Systems Safety and Analysis (DSSA), Plant Systems Branch (SPLB), Fire Protection

Engineering and Special Projects Section, has developed quantitative methods, known as

“Fire Dynamics Tools” (FDT ), to assist regional fire protection inspectors in performing fire hazard s

analysis (FHA). These methods have been implemented in spreadsheets and taught at the NRC’s

quarterly regional inspector workshops conducted in 2001–2003. The goal of the training is to

assist inspectors in calculating the quantitative aspects of a postulated fire and its effects on safe

nuclear power plant (NPP) operation. FDT were developed using state-of-the-art fire dynamics s

equations and correlations that were preprogramed and locked into Microsoft Excel spreadsheets. ® 

These FDT will enable the inspector to perform quick, easy, first-order calculations for the potential s

fire scenarios using today’s state-of-the-art principles of fire dynamics. Each FDT spreadsheet s

also contains a list of the physical and thermal properties of the materials commonly encountered

in NPPs.

The FDT are intended to assist fire protection inspectors in performing risk-informed evaluations s

of credible fires that may cause critical damage to essential safe-shutdown equipment, as required

by the new reactor oversight process (ROP) defined in the NRC’s inspection manual . In the new *

ROP, the NRC is moving toward a more risk-informed, objective, predictable, understandable, and

focused regulatory process. Key features of the new program are a risk-informed regulatory

framework, risk-informed inspections, a significance determination process (SDP) to evaluate **

inspection findings, performance indicators, a streamlined assessment process, and more clearly

defined actions that the NRC will take for plants based on their performance.

This NUREG-series report addresses the technical bases for FDT , which were derived from the s

principles developed primarily in the Society of Fire Protection Engineers (SFPE) Handbook of Fire

Protection Engineering, National Fire Protection Association (NFPA) Fire Protection Handbook, and

other fire science literature. The subject matter of this report covers many aspects of fire dynamics

and contains descriptions of the most important fire processes. A significant number of examples,

reference tables, illustrations, and conceptual drawings are presented in this report to expand

the inspector’s appreciation in visualizing and retaining the material and understanding calculation

methods.

The content of the FDT encompasses fire as a physical phenomenon. As such, the inspector s

needs a working knowledge of algebra to effectively use the formulae presented in this report and

the FDT . Acquired technical knowledge or course background in the sciences will also prove helpful. s

The information contained in this report is similar to, but includes less theory and detail than,

an undergraduate-level university curriculum for fire protection engineering students.
xxxviii

The goal of this report is to develop a common body of knowledge of fire protection and fire science

to enable the inspector to acquire the understanding, skills, and abilities necessary to effectively

apply principles of fire dynamics to analyze the potential effects of a fire in a commercial NPP.

The FDT will advance the FHA process from an approach that is primarily qualitative to one that s

is more quantitative. The development of this report, the FDT , and the quarterly inspector s

workshops conducted in 2001–2003 is the NRC’s first step in achieving that goal.

Toward that end, on November 22 and 23, 2004, the NRC conducted a 2-day public meeting at the

agency’s headquarters in Rockville, Maryland, with the sole purpose of sharing an “advanced copy”

of NUREG-1805 with all interested stakeholders. The meeting was well-received, and the

participants identified numerous suggestions to further refine both the advanced copy and the

spreadsheets. We thank those stakeholders for their involvement and have made every attempt

to include their valued comments in preparing the final files for the publication of this report.

Fire is a complex subject and transfer of its concepts to useful pursuits is a challenge. We hope

that this report and the FDT can make a difference in the NRC’s fire protection inspection program, s

specifically risk-informed fire protection initiatives such as the SDP and risk-informed inspection

of circuits.
xxxix

HOW TO USE THIS NUREG AND THE FDTS

This NUREG-series report and the related Fire Dynamics Tools (FDT ) provide first-order s

quantitative methods (i.e., traditional approaches, correlations, computations, closed form

approximations or exact solutions, and hazard models) to assess the potential fire hazard

development in commercial nuclear power plants (NPPs). This report is divided into chapters

that correspond to FDT . First-time users should read this report in its entirety before performing s

an analysis. Once the basic principles are understood, the FDT can be used to perform fire s

dynamics calculations. As explained in this report, appropriate care must be exercised to apply

the FDT within the limits of their validity. s

The CD-ROM that accompanies this report provides separate folders containing the FDTs

spreadsheets. This text exclusively uses the spreadsheets in the “English Units” folder. The folder

labeled “SI Units” contains the same FDT spreadsheets but requires all user inputs to be s

in SI units.

The chapters and appendices of this report provide basic text on fire protection engineering,

to provide inspectors with an overview of the basic characteristics and behavior of fire, fire hazards

of materials and buildings, and an overview of the fundamental methods of fire protection.

Appendix F to this report contains a glossary of terms used in the field of fire protection engineering.

Appendix I, “Mathematics Review and System of Units,” is included to refresh the inspector’s

understanding of mathematical functions, dimensional consistency in equations, and variables used

in the FDT . Each chapter contains practice problems for the inspector to apply the principles s

learned with the FDT program. Appendix J provides additional problems for added practice. s

Each chapter in this report has one or more spreadsheet(s) based on the method discussed in the

chapter. Each spreadsheet is designed to make the calculation method understandable, and all

of them are in the same format. The input parameter cells in each spreadsheet are identified

in yellow. The user needs to enter data by typing (on the keyboard) and making selections through

the use of pull-down menus and dialog boxes. The spreadsheets also bundle many material

properties to enable the user to select a single input from a table, instead of entering all of the

associated parameters. The user simply needs to select the material from the provided list

(pull-down menu), and the spreadsheet will automatically place the associated property data in the

corresponding green input cells. For example, an inspector can simply click on “concrete” in the

property table, and the correct parameters will appear in the input parameter cells. This will also

eliminate errors in manually entering the properties in the input parameter cells. Where material

properties are not available in the spreadsheet table, the user will have to enter the values manually

without selecting any material from the material properties data table.

The spreadsheets explicitly show the calculation methods — in detail and step-by-step — so that

the inspector can follow the application of the FHA methods. The example problems at the end

of each chapter, and practice problems in Appendix J, have been designed to be solved mainly

with the FDT ; however, in some cases, simple calculations are required before using the FDT .

s s

The results of the calculations are designated by the word “ANSWER” in the spreadsheets.
xl

The FDT spreadsheets are programmed with mathematical equations that can produce “numerical” s

accuracy to any number of decimal places. For consistency, the authors generally chose

two decimal places; however, the user should focus on the magnitude of the results and not attempt

to solve problems by placing critical emphasis on decimal values. For example if a component

is “damaged” at 700°F (371.11°C) and the calculated results indicate 699.99°F (371.10°C), only an

inexperienced user would argue that damage is not probable. In many cases, a resultant close to

690°F (365.55°C) is close enough to suggest damage.

Fire dynamics is a constantly evolving science and rarely dictates a single answer as to how a fire burns.

The user is encouraged to perform bounding calculations as a part of the FHA. This will form a

window of possible, credible solutions. An example of this concept would be to vary ventilation

rates (door open vs. door closed, mechanical ventilation system on vs. off, different vent locations,

etc.).

A final word of caution is in order for users of this report and the accompanying spreadsheets. An

FHA can often be a complex series of calculations and evaluations that are necessary to gain a

comprehensive understanding of the fire risk and its potential effects on NPP safety. This report

provides one important element of that process, namely assisting the user in understanding fire

dynamics; however, this report was never intended to be the “end-all” text for a complete

understanding of fire risk. Experience, engineering judgment, peer review, and other sources of

information will be necessary for a complete understanding of the risk. For example, this report

does not attempt to answer two important questions: “How accurate are the equations in this text?

“Are they ±10%, or do they always over-predict the results?

At the time of this writing, the NRC’s Office of Nuclear Regulatory Research, in cooperation with

the Electric Power Research Institute (EPRI), is subjecting this report to “verification and validation”

(V&V) against another fire dynamics method and three fire models to answer those very questions.

Their final product should help reduce calculation uncertainties and provide additional insights to

the methods and models. Another program that has been recommended is the development of a

fire modeling user’s guide. Such a guide would compile in a usable format the lessons learned from

the V&V exercise, as well as field experience from the use of this report, the accompanying

spreadsheets, and other methods. As such, a user’s guide would help to further improve the overall

quality of fire risk assessments.
xli

ABBREVIATIONS

ABS Acrylonitrile Butadiene Styrene

ACRS Advisory Committee on Reactor Safeguards (NRC)

ADAMS Agencywide Documents Access and Management System (NRC)

ADS Automatic Depressurization System

AFFF Aqueous Film Forming Foam

AFT Adiabatic Flame Temperature

AFW Auxiliary Feedwater

AGA American Gas Association

AHJ Authority Having Jurisdiction

AISI American Iron and Steel Institute

AL Administrative Letter

ALC Approximate Lethal Concentration

ANS American Nuclear Society

ANSI American National Standards Institute

API American Petroleum Institute

ASCE American Society of Civil Engineers

ASCOS Analysis of Smoke Control Systems

ASET Available Safe Egress Time

ASHRAE American Society of Heating, Refrigeration, and Air Conditioning Engineers

ASME American Society of Mechanical Engineers

ASMET Atria Smoke Management Engineering Tools

ASTM American Society for Testing and Materials

AT Auxiliary Transformer

ATF&E Alcohol, Tobacco, Firearms, and Explosives

AWG American Wire Gauge

BFC Bromochlorodifluoro-methane

BFNP Browns Ferry Nuclear Power Plant

BFRL Building and Fire Research Laboratory

BL Bulletin

BLEVE Boiling Liquid, Expanding Vapor Explosion

BOCA Building Officials & Code Administration International

BREAK1 Berkeley Algorithm for Breaking Window Glass in a Compartment Fire

BS British Standard

BTP Branch Technical Position

BTU British Thermal Unit

BWR Boiling-Water Reactor

CCW Component Cooling Water

CFAST Consolidate Model of Fire Growth and Smoke Transport

CFD Computational Fluid Dynamics

CFI Certified Fire Inspector

CFO Chief Financial Officer (NRC)

CFR Code of Federal Regulations

CHF Critical Heat Flux
xlii

CIB Conseil Internationale du Batiment

CIBSI Chartered Institution of Building Services Engineers

CIO Chief Information Officer (NRC)

CL.S.PE Chlorosulfonated Polyethylene

CO Carbon Monoxide

CO2 Carbon Dioxide

CP Construction Permit

CPCV Chlorinated Polyvinylchloride

CPE Chlorinated Polyethylene

CPSC Consumer Product Safety Commission

CR Circular or Neoprene or Chloroprene Rubber

CSNI Committee on the Safety of Nuclear Installations

CSP Chlorosulfonated Polyethylene Rubber (Kel-F )

®

CSR Cable Spreading Room

CTEF Chlorotrifluoroethylene

DDT Deflagration to Detonation Transition

DETACT-QS Detector Actuation Quasi-Steady

DETACT-T2 Detector Actuation Time Square

DID Defense-in-Depth

DOE U.S. Department of Energy

DOT U.S. Department of Transportation

DSSA Division of Systems Safety and Analysis (NRC)

ECCS Emergency Core Cooling System

EDG Emergency Diesel Generator

EDO Executive Director for Operations (NRC)

ELVAC Elevator Evacuation

EMI/RFI Electromagnetic or Radio-Frequency Interface

EPA Environmental Protection Agency

EPR Ethylene-Propylene Rubber

EPRI Electrical Power Research Institute

EQ Equipment Qualification

ESFR Early Suppression Fast Response

ETFE Ethylenetetrafluoroethylene (Tefzel®)

EVA Ethylvinyl Acetate

FAA Federal Aviation Administration

FDI Fire Detection Institute

FDM Fire Demand Model

FDS Fire Dynamics Simulator

FDT Fire Dynamics Tools s

FEM Finite Element Method

FEMA Federal Emergency Management Agency

FEP Fluorinated Polyethylene Propylene (Teflon®)
xliii

FFFP Film-Forming Fluoroprotein Foam

FHA Fire Hazard Analysis

FIGARO II Fire and Gas Spread in Room (model)

FIPEC Fire Performance of Electrical Cables

FIRES-T3 Fire Response of Structures-Thermal Three (model)

FIVE Fire Induced Vulnerability Evaluation

FMRC Factory Mutual Research Corporation

FPA Foote, Pagni, and Alvares

FPE Fire Protection Engineer(ing)

FPETOOL Fire Protection Engineering Tool

FPP Fire Protection Program

FPS Fire Protection System

FR Fire-Retardant

FRP Fiberglass Reinforced Polyester (Plastic)

FRXPE Fire-Retardant Crosslinked Polyethylene

FSSD Post-Fire Safe-Shutdown

FTA Federal Transit Authorization

FTMS Federal Test Method Standard

GDC General Design Criteria

GL Generic Letter

GSA General Service Administration

GSI Generic Safety Issue

H2O Water

HBr Hydrogen Bromide

HCI Hydrogen Chloride

HCN Hydrogen Cyanide

HEPA High-Efficiency Particulate Air Filter

HF Hydrogen Fluoride

HPCI High Pressure Cooling Injection

HRR Heat Release Rate

HTGR High-Temperature Gas-Cooled Reactor

HVAC Heating, Ventilation, and Air Conditioning

IAFSS International Association of Fire Safety Science

IBC International Building Code

ICBO International Conference of Building Officials

ICS Integrated Control System

ICSDTS International Committee for the Study and Development of Tubular Structures

IE Initiative Events

IEC International Electrotechnical Commission

IEEE Institute of Electrical and Electronic Engineers

IN Information Notice

INEEL Idaho National Engineering and Environmental Laboratory

IPEEE Individual Plant Examination of External Events

ISO International Organization for Standardization
xliv

LAVENT Link Actuation Vents

LC Lethal Concentration

LCL Lethal Concentration Low

LD Lethal Dose

LDL Lethal Dose Low

LEL Lower Explosive Limit

LER Licensee Event Report

LFL Lower Flammability Limit

LIFT Lateral Ignition and Flame Spread (ASTM E 1321 Standard Test Method)

LLNL Lawrence Livermore National Laboratory

LNG Liquified Natural Gas

LOC Limiting Oxidant Concentration

LOCA Loss-of-Coolant Accident

LPG Liquid Propane Gas

LWR Light-Water Reactor

MCC Motor Control Center

MCR Main Control Room

MESG Maximum Experimental Safe Gap

MOV Motor-Operated Valve

MQH McCaffrey, Quintiere, and Harkleroad

NBC National Building Code

NBR Nitrile

NBS National Bureau of Standards

NEA Nuclear Energy Agency

NEI Nuclear Energy Institute

NEMA National Electrical Manufacturers Association

NFC National Fire Code

NFPA National Fire Protection Association

NIOSH National Institute of Occupational Safety ad Health

NIST National Institute of Standards and Technology

NO2 Nitrogen Dioxide

NOUN Notification of Unusual Event

NPP Nuclear Power Plant

NRC U.S. Nuclear Regulatory Commission

NRR Office of Nuclear Reactor Regulation (NRC)

NUREG NUclear REGulatory Guide

OCIO Office of Chief Information Officer (NRC)

OL Operating License

ORNL Oak Ridge National Laboratory

OSHA Occupational Safety and Health Administration

OSU Ohio State University
xlv

PASS Personal Alert Safety System

PC Polycarbonate

PDA Primary Disconnect Assembly

PE Polyethylene

PEF Polyethylene Fluoride

PES Polyethersulphone

PFA Perfluoroalkoxy Branched Polymers

PMMA Polymethylmethacrylate

PP Polypropylene

PPE Polytetrafluoroethylene

PRA Probabilistic Risk Assessment

PS Polystyrene

PTEF Polytetrafluoroethylene (Teflon®)

PU Polyurethane

PVC Polyvinylchloride

PVF Polyvinylfluoride

RCP Reactor Coolant Pump

RES Office of Nuclear Regulatory Research (NRC)

RG Regulatory Guide

RHR Residual Heat Removal

RIS Regulatory Issue Summary

RMV Respiratory Minute Volume

ROP Reactor Oversight Process

RTECS Registry of the Toxic Effects of Chemical Substance

RTI Response Time Index

RWFD Red Wing Fire Department

S/G Steam Generator

SBC Standard Building Code

SBCCI Southern Building Code Congress International

SBDG Standby Diesel Generator

SBR Styrene Butadiene Rubber

SCBA Self-Contained Breathing Apparatus

SDP Significance Determination Process

SER Significant Event Report

SFPE Society of Fire Protection Engineers

SI System International

SNL Sandia National Laboratories

SOLAS Safety of Lives at Sea

SONGS San Onofre Nuclear Generating Station

SPLB Plant Systems Branch (NRC)

SRP Standard Review Plan (NUREG-0800)

SSC Structure, System, and/or Component
xlvi

TASEF Temperature Analysis of Structure Exposed to Fire

TCL Toxic Concentration Low

TDL Toxic Dose Low

TFE Tetrafluoroethylene (Teflon®)

TLC Toxic Concentration Low

TLV Threshold Limit Value

TNT Trinitrotoluene

TRP Thermal Response Parameter

TSC Technical Support Center

TTC Time-Temperature Curve

TVA Tennessee Valley Authority

TVAN Tennessee Valley Authority Nuclear Program

UBC Uniform Building Code

UEL Upper Explosive Limit

UFC Uniform Fire Code

UFL Upper Flammability Limit

UL Underwriters Laboratories

UPS Uninterruptible Power Supply

USFA United States Fire Administration

UVCE Unconfined Vapor Cloud Explosion

V&V verification and validation

VRLA Valve-Regulated Lead Acid

W/D Weight-to-Heated Perimeter Ratio

XLPE Crosslinked Polyethylene

XLPO Crosslinked Polyolefin
xlvii

NOMENCLATURE

Ac Compartment floor area

Ae Surface of element

Af Horizontal burning area of fuel

AH Ampere hours

As Cross sectional area

AT Area of compartment enclosing surfaces (excluding vent areas)

Av Area of ventilation openings

b Flame spread parameter

C Gas concentration by volume

c Thermal capacity

i

c Specific heat of insulation

p

c Specific heat

s

c Specific heat of steel

v

c Specific heat at constant volume

CHF Critical heat flux for ignition

D Diameter

D Heated parameter

DSC Scaled distance

E Emissive power

E Explosive energy released

F Configuration or shape factor

F Fire resistance time

FTP Flux time product

Fc Float Current per 100 AH

g Acceleration of gravity

G Gas discharge rate

h Thickness of insulation

h Heat flux time product index

hc Compartment height

heff Effective heat transfer coefficient

hig Heat transfer coefficient at ignition

hk Convective heat transfer coefficient

hv Height of ventilation opening

H Thermal capacity of steel section at ambient

H Height

Hg Hydrogen gas generation

Hf Flame height

Hf(wall) Wall flame height

Hf(wall,line) Line fire flame height

Hf(corner) Corner fire flame height
xlviii

k Thermal conductivity

i

k Thermal conductivity of insulation

k c Thermal inertia

K Mixing efficiency factor

K Proportionality constant

c

l Compartment length

L Length

LFL Lower flammability limit

m Mass

mf Mass of fuel vapor

mf Mass of fuel burned

mp Mass concentration of particulate

Mass flow rate

Mass entrainment rate

Mass flow rate of fuel

Mass flow rate out of enclosure

Plume mass flow rate

Mass loss rate per unit area

Mp Mass of particulates produced

N Number of cells (batteries)

N Number of theoretical air changes

P Pressure

Heat flux

Critical heat flux

External heat flux

Minimum heat flux required for ignition

Radiative heat flux

Q Volume of air

Qtotal Total energy release

Heat release rate or energy release rate

Convective energy release rate

Energy release rate to cause flashover

Full-scale energy release rate

Bench-scale energy release rate
xlix

r Radius

R Radial distance

R Fire Resistance

RTI Response time index

S Visibility

t Time

b

t Burning duration

D

t Detection time

ig t Ignition time

p

t Thermal penetration time

r

t Detector response time

t

t Smoke transit time

activation t Sprinkler activation time

T Temperature

Ta Ambient temperature

Tf Fire temperature

TFO(max) Post-flashover compartment temperature

Tg Gas temperature

Ts Steel temperature

Tjet Ceiling jet temperature

Tp(centerline) Plume centerline temperature

Tactivation Activation temperature

ujet Ceiling jet velocity

uw Wind velocity

uo Gas velocity

u* Nondimensional wind velocity

V Volume

Vdef Volume of gas for deflagration

w Fuel exposed width

wc Compartment width

W Weight of steel column per linear foot

WTNT Weight of TNT

p

y Particulate yield

z Height of smoke layer interface above floor

o

z Hypothetical virtual origin of fire source

Zp Fireball flame height

Hc Heat of Combustion

Hc,eff Effective heat of combustion

t Time step

Tg Gas temperature above ambient

Tig Ignition temperature above ambient

Heat transfer coefficient for steel
l

Yield (fraction of available energy participating in blast wave generation)

m Specific extinction coefficient

r Fraction of total energy radiated

Thickness

Flame emissivity

Ventilation factor

Flame title or angle of deflection

Density

a Density of Ambient Air

c Density of combustion products

c Density of concrete

F Density of fuel vapor

g Density of gas

i Density of insulation

Stafan-Boltzmann constant

o Detector time constant

Regression rate

Subscripts

a Ambient

bs Bench-scale

c Compartment

c Combustion

c Concrete

c Current

D Detection

def Deflagration

e Convective

e External

eff Effective

e Entrainment

f Fire

f Flame

f Fuel

f(corner) Corner flame

f(wall) Wall flame

f(wall,line) Line fire flame

FO Flashover

fs Full-scale

g Gas

H Hours

I Insulation

ig Ignition

jet Ceiling jet

m Extinction

min Minimum

o Out
li

p Specific

p Particulate

p Plume

p Penetration

r Radiative

r Response

SC Scale

s Steel

T Total

total Total

t Transient

TNT Trinitrotoluene

v Vent

v Volume

w Wind

Superscripts

( ) Per unit time @

( )” Per unit area

( )” Per unit are, per unit time @

* Nondimensional

1-1

CHAPTER 1. INTRODUCTION

1.1 Purpose

The purpose of this NUREG-series report is to introduce the principles of fire dynamics and

illustrate how fire protection inspectors can apply those principles in a risk-informed manner

to better determine whether credible fire scenarios are possible. In this context, we broadly define

the term “fire dynamics” as the scientific study of hostile fires. The dynamic nature of fire is a

quantitative and mathematically complex subject. It combines physics, chemistry, mathematics,

and engineering principles and can be difficult to comprehend for those who have a limited

background in these areas. With the objective of quantitatively describing fire and related

processes (i.e., ignition, flame spread, fire growth, and smoke movement) and their effects in an

enclosure, the Fire Dynamics Tools (FDT ) have been developed to assist fire protection inspectors s

in solving fire hazard problems in nuclear power plants (NPPs).

The goal of this report is to provide insights into fire dynamics, without using the sophisticated

mathematics that are normally associated with the study of fire dynamics. Nonetheless, inspectors

will need a working knowledge of algebra, reading graphs, scientific notation, formulas, and use of

some simple mathematics functions to understand the quantitative aspect of fire phenomena.

A better understanding of these processes will improve the quality of fire protection inspections

conducted by the U.S. Nuclear Regulatory Commission (NRC).

1.2 Objective

The primary objective of this report is to provide a basic calculation methodology for use in

assessing potential fire hazards in the NRC-licensed NPPs. The methodology uses simplified,

quantitative fire hazard analysis (FHA) techniques to evaluate the potential for credible fire

scenarios. One purpose of these evaluations is to determine whether a potential fire can cause

critical damage to safe-shutdown components, either directly or indirectly by igniting intervening

combustibles. The methodology used in this report is founded on material fire property data

implemented in scientific calculations. In addition, the associated techniques have been assessed

to ensure applicability and accuracy, and were derived primarily from the principles developed in

the Society of Fire Protection Engineers (SFPE) Handbook of Fire Protection Engineering, and the

National Fire Protection Association (NFPA) Fire Protection Handbook. The FHA methods have

been implemented as Microsoft Excel spreadsheets, which incorporate simple, empirical ®

correlations and detailed mathematical equations based on fire dynamics principles. They also

build on numerous tables of material fire property data, which have been assembled for NPPs. The

combination of these spreadsheets and data tables forms the basis for the FDT .

s

1.3 Regulatory Background on Fire Protection for Nuclear Power Plants

The primary objectives of fire protection programs (FPPs) at U.S. NPPs are to minimize both the

probability of occurrence and the consequences of fire. To meet these objectives, the FPPs for

operating NPPs are designed to provide reasonable assurance, through defense-in-depth (DID),

that a fire will not prevent the performance of necessary safe-shutdown functions and that

radioactive releases to the environment in the event of a fire will be minimized. Section II, “General

Requirements,” of Appendix R to Title 10, Part 50, of the Code of Federal Regulations (10 CFR
1-2

Part 50), states that the fire protection program shall extend the DID concept to fire protection

in fires areas that are important to safety, with the following objectives:

(1) Prevent fires from starting.

(2) Rapidly detect, control, and extinguish those fires that do occur.

(3) Protect structures, systems, and components that are important to safety so that a fire that

is not promptly extinguished by the fire suppression activities will not prevent the safe

shutdown of the plant.

The first element of this DID approach deals with preventing fires from starting. This can be

accomplished by limiting fire sources that could initiate a fire at an NPP, and preventing any existing

ignition sources from causing self-sustaining fires in combustible materials. Despite the nuclear

industry’s best efforts to eliminate or at least control ignition sources, accidental (and purposeful)

sources of ignition often exist and can result in hostile fires. This is an important aspect of a total

fire safety program, which should not be overlooked.

The second element of the prevention element deals with rapidly detecting, controlling, and

extinguishing those fires that do occur. This can be achieved by preventing significant fires from

occurring, given the inadvertent or purposeful introduction of an ignition source. If all structures and

contents comprised totally noncombustible materials, this would not pose a problem. However, this

is not the case. Buildings and their contents are composed of a variety of materials of various

degrees of combustibility. Materials with higher thresholds of ignition and less hazardous

combustion are continually being developed. Regardless, at least in some cases, the higher

resistance to ignition can also result in a higher resistance to fire extinction (Hill, 1982). Electrical

cables are a good example. While cables qualified to the Institute of Electrical and Electronic

Engineers (IEEE) Standard 383 are more fire-resistant, they are also more difficult to extinguish

once they ignite. In any case, the prevention of hostile fires will likely never be the total solution to

the fire safety problem in NPPs.

The second element of the DID approach involves limiting fire spread through fire detection and fire

suppression. There are various approaches to this element. In the event of a significant fire,

its spread might be limited in the following ways:

• early human detection and manual suppression

• provision and maintenance of adequate fire detection and automatic fire suppression systems

• a combination of manual and automatic detection and suppression systems

Heat 2 and smoke detectors; fire alarm systems; Halon 1301, carbon dioxide (CO ), and dry chemical

fire suppression systems; automatic sprinkler, foam, and water spray systems; portable fire

extinguishers; hose stations, fire hydrants, and water supply systems; and fire brigades are all part

of the second element of the DID approach. Each is highly developed in modern fire protection

designs, and is constantly being further refined as fire technology advances. Nonetheless, the DID

concept recognizes that the first two elements of fire defense are not always entirely successful

in meeting the fire challenge.

The third element of the DID approach involves designing NPP structures, systems, and

components (SSCs) to prevent significant damage in the event that the first two elements fail, either

partially or fully. This goal may be fulfilled in the following ways:
1-3

• Isolate combustible elements by spatial separation, such that a fire in one fuel package will

not propagate to any other fuel package.

• Isolate combustible elements by fire-resistant barriers to prevent fires from propagating from

one area to another. In particular, fire-rated horizontal and vertical barrier systems will limit

fire spread from compartment to compartment.

The NRC’s regulatory framework for FPPs at U.S. NPPs is described in a number of regulatory and

supporting guidelines, including but not limited to General Design Criterion (GDC) 3, as specified

in Appendix R to Title 10, Part 50, of the Code of Federal Regulations (10 CFR Part 50); 10 CFR

50.48; Appendix R to 10 CFR Part 50; Regulatory Guide (RG) 1.189 and other regulatory guides,

generic communications (e.g., generic letters, bulletins, and information notices), NUREG-series

reports; the standard review plan (NUREG-0800); and associated branch technical positions

(BTPs).

1.4 Fire Hazard Analysis for Nuclear Power Plants

As previously stated, fire protection for NPPs relies on the DID concept to achieve the required

degree of reactor safety by using redundant levels of administrative controls, fire protection systems

and features, and safe-shutdown capability. An FHA should be performed to assess the fire hazard

and demonstrate that the NPP will maintain its ability to perform safe shutdown functions and

minimize radioactive material releases to the environment in the event of a fire.

RG 1.189 lists the following objectives for an FHA:

• Consider potential in situ and transient fire hazards.

• Determine the consequences of fire in any location in the plant, paying particular attention

to the impact on the ability to safely shut down the reactor or the ability to minimize and

control the release of radioactivity to the environment.

• Specify measures for fire prevention, fire detection, fire suppression, and fire containment,

as well as alternative shutdown capability for each fire area containing SSCs that are

important to safety in accordance with NRC guidelines and regulations.

1.5 Fire Protection Inspection Findings

Fire protection inspection findings are generally classified as weaknesses associated with one or

more objectives of the DID elements introduced above. If a given inspection does not yield any

DID-related findings against a fire protection feature or system, the fire protection feature and

system are considered to be capable of performing their intended functions and operating in their

normal (standby) state.
1-4

1.6 Fire Scenario Development for Nuclear Power Plants

In the broadest sense, a fire scenario can be thought of as a specific chain of events that begins

with the ignition of a fire and ends either with successful plant shutdown or core damage. The fire

is postulated to occur at a specific location in a specific fuel package, and to progress through

various stages of fire growth, detection, and suppression. In this process, the fire may damage

some set of plant equipment (usually electrical cables). For a given fire source, the FHA may

postulate damage to various sets of equipment, depending on how long the fire burns and how

large the initial fire is presumed to be. The postulated or predicted fire damage may either directly

or indirectly cause the initiating event (such as a plant trip, loss of offsite power, etc.).

When inspectors develop a fire scenario, they should postulate the worst-case, realistic fire,

provided that the compartment and configuration of the fire area, room, or zone can support such

a fire. For example, a large cabinet fire is one in which fire damage initially extends beyond the

cabinet in which the fire originated. The fire damage attributed to a large cabinet fire often extends

into the overhead cabling, an adjacent cabinet, or both. A large fire for a pump or motor can often

be based initially upon the largest (worst-case) oil spill from the equipment. If the configuration of

the compartment, combustibles, etc., supports further growth of the large fire, the fire scenario

should postulate that growth. Since scenarios that describe large fires are normally expected to

dominate the risk-significance of an inspection finding, scenarios with small fires typically are not

included unless they spread and grow into large fires.

1.7 Process of Fire Development

Fire hazards to NPP equipment can arise from many sources, including (but not limited to) thermal

damage, fouling, and corrosivity. Fire is essentially a chemical reaction involving solids, liquids, and

gases that ignite and undergo a rapid, self-sustaining oxidation process, accompanied by the

evolution of heat and light of varying intensities. However, the chemical and physical reactions that

take place during a fire are extremely complex and often difficult to describe completely. The most

common fires start as a result of the ignition of solid or liquid fuels (combustible materials). Solid

and liquid fuels typically become volatile and serve as suppliers of gaseous fuel to support

combustion. In the physical model (illustrated in Figure 1-1) the process of fire development begins

when the fuel surface starts to heat up as a result of heat transfer from the adjacent surroundings.

As the temperature of the fuel surface increases in response to this heat input, the fuel surface

begins to emit fuel vapors. The fuel vapors mix (by convection and diffusion) with oxygen in the

adjacent boundary layer, ignite (through a chemical reaction), and release additional heat. Some

of this liberated heat energy may further increase the surface temperature of the fuel and thereby

accelerate the fire growth process.

Many materials react with oxygen to some degree; however, various materials differ in their

respective rates of reaction. The difference between slow-and rapid-oxidation reactions is that the

latter occur so rapidly that heat is generated faster than it is dissipated, causing the material being

oxidized (fuel) to reach its ignition temperature. Once a material reaches its ignition temperature,

it ignites and continues to burn until either the fuel or the oxygen is consumed. The heat released

during combustion is usually accompanied by a visible flame. However, some materials (such as

charcoal) smolder, rather than producing a visible flame. A familiar slow-oxidation reaction is the

rusting of iron. Such a reaction releases heat so slowly that the temperature hardly increases more

than a few degrees above the temperature of the surroundings. These reactions typically do not

cause fires and are not considered combustion.
1-5

Figure 1-1 Physical Process of Combustion and Fire

Generally, three components are required to support combustion. These three components— fuel,

oxygen, and heat source—are depicted in Figure 1-2, which is commonly called the fire triangle.

The fire triangle shows that for combustion to occur, fuel, an oxidizing agent, and a heat source

must be present in the same place at the same time. If any one of the legs of the triangle is

removed, the combustion process will not be sustained. This is the most basic description of the

fire phenomenon. It is applicable for most scenarios, with the exception of fire extinguishment

involving dry chemicals and Halons.

Figure 1-2 The Fire Triangle
1-6

1.8 The Fire Hazards

The fire load of NPPs is different than that of fossil-fuel power plants and many other industrial

plants. An NPP does not have a constant flow of fuel (e.g., coal or oil) as the hazard. However,

an NPP may have similar fire hazards, such as grouped electrical cables and lubricating oils (e.g.,

turbine, reactor coolant pumps). Table 1-1 lists the combustibles and hazardous materials that are

commonly present in NPPs.

Table1-1. Common Combustible and Hazardous Materials in NPPs

Combustible solid fuels

Cable insulation and jackets

Other thermal and electric insulation materials ( e.g., pipe insulation)

Building materials

Combustible metal deck and roof assemblies

Filtering materials including charcoal and high-efficiency particulate air (HEPA) filters

Packing materials and waste containers

Flexible materials used in connection with a seismic design, including flexible joints

Sealing materials (e.g., asphalt, silicone foam, neoprene, etc.)

Solidification agents for packing compacted radioactive waste conditioning (e.g., bitumen)

Low-level radioactive waste material (e.g., paper, plastic, anti-C-zone clothing, rubber shoes and

gloves, overalls, etc.)

Combustible and flammable liquid fuels

Lubricants, hydraulic oil, and control fluids

Conventional fuels for emergency power units, auxiliary boilers, etc.

Paints and solvents

Explosive and flammable gaseous fuels

Hydrogen to cool the generators

Propane or other fuel gases, such as those used for starting boilers, burning radwaste, etc.

Oxygen and hydrogen radiolysis of reactor coolant water within the pressure vessel and addition of

hydrogen for improved recombination

Hydrogen generated in battery room as a result of overcharging a battery

The quantities and locations of these combustibles vary among NPPs. More importantly,

identification of these combustibles and their characteristics only partially identifies the associated

fire hazard. The bearing that the fire hazards have on nuclear safety must also be considered in

defining the total fire hazard. Nuclear safety factors include maintaining the safe-shutdown

capability and preventing radiation releases that exceed acceptable limits.

Fire hazards related to NPPs include (but are not limited) to the following examples:

• fire hazard associated with electrical cable insulation

• fire hazard of ordinary combustibles

• oil fire hazards associated with large reactor coolant pump motors

• oil fire hazard involving emergency turbine-driven feedwater pumpsdiesel fuel fire hazard

at diesel-driven generators

• fire hazard involving charcoal in filter units

• fire hazard associated with flammable offgases

• fire hazard of protective coatings

• fire hazard of turbine lube oil and hydrogen seal oil
1-7

• hydrogen cooling gas fire hazard in turbine generator buildings

• fire hazard associated with electrical switchgear, motor control centers (MCCs), electrical

cabinets, load centers, inverter, circuit boards, and transformers

1.8.1 Combustible Materials Found in Nuclear Power Plants

Combustible materials may be found in both large and small concentrations in NPPs. One can

assume that outbreaks of fire may occur as a result of a variety of ignition sources. In general, the

combustible materials in an NPP can be divided into four broad fuel categories, including

(1) transient solid and liquid fuels, (2) in situ combustible consisting both solid and liquid fuels,

(3) liquid fuels used in NPP equipment, and (4) explosive and flammable gases, as described in the

following sections.

1.8.1.1 Transient Combustibles

Solid transient fuels include general trash, paper waste, wood, plastics, cloth, and

construction/modification materials. By contrast, liquid transient fuels commonly include cleaning

solvents, paints, and lubricants being transported through the NPP for maintenance of plant

equipment. These fuels are generally found in small quantities in most NPP areas at any given time.

1.8.1.2 In Situ Combustibles

The most common category of potential fuels found in NPPs is that of in situ solid fuel elements.

Of these, the largest single potential fuel source is cable insulation and jacketing materials. Several

factors combine to support the conclusion that cable insulation and jacketing material far and away

represent the most important materials to be considered in an NPP FHA, although any other plastic

compounds installed in the NPP must also be included in the FHA. Cable insulation and jackets

are typically manufactured using organic compounds and, therefore, they will burn under the proper

circumstances.

The fire hazard associated with electrical cable insulation and jackets in NPPs is similar to that of

other occupancies (e.g., telephone exchange) that use cable trays to support a large number of

power, control, and instrument cables. However, an additional factor in NPPs is the added hazard

associated with loss of reactor safety system redundancy.

A wide variety of cable insulation and jacketing materials can be commonly found in any given NPP.

Cable insulation and jackets commonly encountered in an NPP include materials based on the

following compounds:

• acrylonitrile-butadiene-styrene (ABS)

• chlorinated polyvinylchloride (CPVC)

• chlorosulfonated polyethylene rubber (CSP) (Hypalon )

®

• chlorotrifluoroethylene (CTEF) (Kel-F )

®

• cross-linked polyolefin (XLPO) including the more specific class of cross-linked

polyethylene (XLPE)

• ethylenetetrafluoroethylene (ETFE) (Tefzel )

®

• ethylene-propylene rubber (EPR)

• fluorinated polyethylene propylene (FEP) (Teflon )

®

• neoprene or chloroprene rubber (CR)
1-8

• polycarbonate (PC)

• polyethylene (PE)

• polyethylene fluoride (PEF)

• polyethersulphone (PES)

• polypropylene (PP)

• polystyrene (PS)

• polytetrafluoroethylene (PTEF) (Teflon )

®

• polyurethane (PU)

• polyvinyl chloride (PVC)

• silicone and silicone/rubber compounds

• styrene-butadiene rubber (SBR)

• tetrafluoroethylene (TFE) (Teflon )

®

1.8.1.3 Liquid Fuels

Liquid fuels include lubricating and cooling oils, cleaning solvents, and diesel fuels. These items

are commonly used in pumps, motor generators, hydraulic-operated equipment, diesel-driven

engines, transformers, and other equipment that require lubrication and cooling with heat

transferring oils. Fires involving such types of equipment are relatively common and usually results

from leakage or overheating.

1.8.1.4 Explosive and Flammable Gases

Explosive and flammable gases are often present in an NPPs. The most common is hydrogen,

which is present as a blanket inside the main generator and a byproduct of reactor operation

(through dissociation of water). Battery rooms in NPPs are also a source of hydrogen gas

production.

Gases can be categorized as flammable and nonflammable. In addition, some gases are not

flammable but support combustion. For example, oxygen does not burn; however, most fires burn

more rapidly if the oxygen concentration is increased.

A general word of caution about gaseous fuels: when a compressed gas, like butane, is released,

the visible vapor cloud indicates that the gas is colder than the air temperature and, consequently,

condensing the moisture in the air. It appears much like a fog; however, this visible cloud is not the

extent of the gaseous vapor. This is because the vapor disappears from view as it warms up, but

may still linger in the area. Thus, it is possible to stand in an invisible gaseous vapor with a

concentration that is within the flammable range. If the vapor were to ignite, the person could be

burned severely, if not killed.
1-9

1.9 Location of the Fire

Exposure fires involving transient combustibles are assumed to have an equal probability of

occurring anywhere in a space or an enclosure, while fires involving fixed combustibles are

assumed to occur at the site of the fixed combustible. Since the hazard is greater when a fire is

located directly beneath a target (e.g., cable tray or electrical cabinet), this placement is normally

evaluated for scenarios involving transient combustibles. For fixed combustibles, the actual

geometry between the source and the target is evaluated to determine whether the target is located

in the fire plume or ceiling jet region.

1.10 Risk-Informed, Performance-Based Fire Protection

Risk-informed, performance-based fire protection is an integration of decision-based and

quantitative risk assessment with a defined approach for quantifying the performance success of

fire protection systems (FPSs) (Barry, 2002).

Performance-based fire safety engineering is defined as “An engineering approach to fire protection

design based on (1) agreed upon fire safety goals, loss objectives, and design objectives;

(2) deterministic and probabilistic evaluation of fire initiation, growth, and development; (3) the

physical and chemical properties of fire and growth effluents; and (4) a quantitative assessment of

the effectiveness of design alternatives against objectives,” (Custer and Meacham, 1997).

One primary difference between prescriptive and performance-based designs is that a fire safety

goal, life safety, property protection, mission continuity, and environmental impact are explicitly

stated in the performance-based design, while prescriptive requirements may inhibit fire safety

components from the design. Performance-based fire protection design is widely gaining

acceptance by various countries around the world including United States. The application of

performance-based approach to fire safety analysis will certainly continue to gain widespread

acceptance in the future as an alternative to prescriptive building and fire codes.

Risk is a quantitative measure of fire incident loss potential in terms of both the event likelihood and

aggregate consequences. In the risk-informed approach, the analyst considers the likelihood that

a fire will occur, as well as its potential severity of a fire and consequences. For example, based

on the knowledge and experience of the equipment operator, a fire in a given turbine generator is

likely to occur 80 percent of the time. Similarly based on the knowledge and experience of the fire

protection engineer, the sprinkler system protecting that generator is 90-percent likely to contain

and control that fire. Because the risk-informed, performance-based methodology quantifies the

likelihood of a fire hazard and the likelihood that the fire protection system will contain or control the

fire, it provides a more realistic prediction of the actual risk.

The risk-informed, performance-based approach presents a more realistic predication of potential

fire hazards for a given system or process or for an entire operation. The performance-based

approach provides solutions based on performance to established goals, rather than on prescriptive

requirements with implied goals. Solutions are supported by operator and management about

processes, equipment, and components; the buildings or structural housing them; operation data

and maintenance personnel; and the fire protection systems in place. Published performance data

pertaining to these aspects are also incorporated into the analysis.
1-10

1.11 Data Sources for Combustible Materials Found in Nuclear Power Plants

The following references provide fire property data related to NPPs:

Chavez, J.M., “An Experimental Investigation of Internally Ignited Fires in Nuclear Power Plant

Control Cabinets: Part I, Cabinet Effects Tests,” NUREG/CR-4527, Volume 2, U.S. Nuclear

Regulatory Commission, Washington, DC, April 1987.

Chavez, J.M., “An Experimental Investigation of Internally Ignited Fires in Nuclear Power Plant

Control Cabinets: Part II, Room Effects Tests,” NUREG/CR-4527, Volume 1, U.S. Nuclear

Regulatory Commission, Washington, DC, November 1988.

Chavez, J.M., and L.D. Lambert, “Evaluation of Suppression Methods for Electrical Cables Fires,”

NUREG/CR-3656, U.S. Nuclear Regulatory Commission, Washington, DC, October 1986.

Chan, M.K.W., and J. Mishima, “Characteristics of Combustion Products: A Review of the

Literature,” NUREG/CR-2658, U.S. Nuclear Regulatory Commission, Washington, DC, July 1983.

Cline, D.D., W.A., Von Riesemann, and J.M. Chavez, “Investigation of Twenty-Foot Separation

Distance as a Fire Protection Method as Specified in 10 CFR 50, Appendix R,” NUREG/CR-3192,

U.S. Nuclear Regulatory Commission, Washington, DC, October 1983.

Cooper, L.Y., and K.D. Steckler, “Methodology for Developing and Implementing Alternative

Temperature-Time Curves for Testing the Fire Resistance of Barriers for Nuclear Power Plant

Applications,” NUREG-1547, U.S. Nuclear Regulatory Commission, Washington, DC, August 1996.

Delichatsios, M.A., “Categorization of Cable Flammability Detection of Smoldering and Flaming

Cable Fires,” EPRI-NP-1630, Electric Power Research Institute, Palo Alto, California, November

1980.

Dey, M., A.A. Azarm, R. Travis, G. Martinez-Guridi, and R. Levine, “Technical Review of RiskInformed, Performance-Based Methods for Nuclear Power Plant Fire Protection Analysis,” NUREG1521, Draft Report for Public Comments, U.S. Nuclear Regulatory Commission, Washington, DC,

July 1988.

Keski-Rahkonen, O., J. Mangs, and A. Turtola, “Ignition of and Fire Spread on Cables and

Electronic Components,” VTT Publication 387, Technical Research Center of Finland, Espoo,

Finland, 1999.

Klamerus, L.J., “Electrical Cables Fire Suppression Tests with Halon 1301,” SAND81-1785, Sandia

National Laboratories, Albuquerque, New Mexico, August 1981.

Lee, B.T., “Heat Release Rate Characteristics of Some Combustibles Fuel Sources in Nuclear

Power Plants,” NBSIR 85-3195, U.S. Department of Commerce, National Bureau of Standards

(NBS), Washington, DC, July 1985.

Lee, J.L., and R.F. Pion, “Categorization of Cable Flammability, Part I: Laboratory Evaluation of

Cable Flammability Parameters,” EPRI-NP-1200, Electric Power Research Institute, Palo Alto,

California, July 1980.
1-11

Lee, J.L., “A Study of Damageability of Electrical Cables in Simulated Fire Environments,”

EPRI NP-1767, Electric Power Research Institute, Palo Alto, California, March 1981.

Lukens, L.L., “Nuclear Power Plant Electrical Cable Damageability Experiments,” NUREG/CR-2927,

U.S. Nuclear Regulatory Commission, Washington, DC, October 1982.

Mangs, J., and O. Keski-Rahkonen, “Full-Scale Fire Experiments on Electronic Cabinets,”

VTT Publication 186, Technical Research Center of Finland, Espoo, Finland 1994.

Mangs, J., J. Paananen, and O. Keski-Rahkonen, “Calorimetric Fire Experiments on Electronic

Cabinets,” Fire Safety Journal, Volume 38, No. 2, pp. 165–186: 2003.

Mangs, J., and O. Keski-Rahkonen, “Full-scale Fire Experiments on Electronic Cabinets,”

VTT Publication 186, Technical Research Center of Finland, Espoo, Finland 1994.

Newman, J.S., and J.P. Hill, “Assessment of Exposure Fire Hazards to Cable Trays,”

EPRI NP-1675, Electric Power Research Institute, Palo Alto, California, January 1981.

Nicolette, V.F., and S.P. Nowlen, “A Critical Look at Nuclear Electrical Cable Insulation Ignition and

Damage Thresholds,” SAND-88-2161C, Sandia National Laboratories, Albuquerque, New Mexico,

1989.

Nowlen, S.P., “Heat and Mass Release for Some Transient Fuel Sources Fires: A Test Report,”

NUREG/CR-4680, U.S. Nuclear Regulatory Commission, Washington, DC, October 1986.

Nowlen, S.P., “Quantitative Data on the Fire Behavior of Combustible Materials Found in Nuclear

Power Plants: A Literature Review,” NUREG/CR-4679, U.S. Nuclear Regulatory Commission,

Washington, DC, February 1987.

Nowlen, S.P., “A Summary of Nuclear Power Plant Fire Safety Research at Sandia National

Laboratories, 1975–1987,” NUREG/CR-5384, U.S. Nuclear Regulatory Commission, Washington,

DC, December 1989.

Ramsey, C.B., and M. Modarres, Commercial Nuclear Power, Assuring Safety for the Future,

Chapter 7, “Nuclear Fire Protection (An Example of External Event Analysis),” John Wiley & Sons,

Inc., New York, pp. 295–363, 1998.

Raughley, W.S., and G.F. Lanik, “Operating Experience Assessment Energetic Faults in 4.16-kV

to 13.8-kV Switchgear and Bus Ducts that Caused Fires in Nuclear Power Plants 1986–2001,”

ADAMS Accession # ML021290359, Office of Nuclear Regulatory Research, U.S. Nuclear

Regulatory Commission, Washington, DC, February 2002.

Salley, M.H., “An Examination of the Methods and Data Used to Determined Functionality of

Electrical Cables When Exposed to Evaluated Temperatures as a Result of a Fire in a Nuclear

Power Plant,” Master of Science Thesis, Department of Fire Protection Engineering, University of

Maryland, College Park, Maryland, 2000.
1-12

Sumitra, P.S., “Categorization of Cable Flammability, Intermediate-Scale Fire Tests of Cable Tray

Installations,” Interim, Report, EPRI-NP-1881, Electric Power Research Institute, Palo Alto,

California, August 1981.

Tanaka, T.J., S.P. Nowlen, and D.J. Anderson, “Circuit Bridging of Components by Smoke,”

NUREG/CR-6476, U.S. Nuclear Regulatory Commission, Washington, DC, October 1996.

Tanaka, T.J., “Effects of Smoke on Functional Circuits,” NUREG/CR-6543, U.S. Nuclear Regulatory

Commission, Washington, DC, October 1997.

Tanaka, T.J., E. Baynes, S.P. Nowlen, J. Brockmann, L. Gritzo, S. Christopher, “LDRD Report:

Smoke Effects on Electrical Equipment, SAND2000-0599, Sandia National Laboratories,

Albuquerque, New Mexico, March 2000.

Wyant, F.J., and S.P. Nowlen, “Cable Insulation Resistance Measurements Made During Cable Fire

Tests,” NUREG/CR-6776, U.S. Nuclear Regulatory Commission, Washington, DC, June 2002.

1.12 References

Barry, T.F., Risk-Informed, Performance-Based Industrial Fire Protection, T.F. Barry Publications

and Tennessee Valley Publishing, Knoxville, Tennessee, 2002.

Code of Federal Regulations, Title 10, Energy, Section 50.48, “Fire Protection,” U.S. Government

Printing Office, Washington DC.

Code of Federal Regulations, Title 10, Energy, Part 50, Appendix A, “General Design Criterion 3 —

Fire Protection,” U.S. Government Printing Office, Washington DC.

Code of Federal Regulations, Title 10, Energy, Part 50, Appendix R, “Fire Protection Program for

Nuclear Power Facilities Operating Prior to January 1, 1979,” U.S. Government Printing Office,

Washington DC.

Custer, R.L.P., and B.J. Meacham, Introduction to Performance-Base Fire Safety, Society of Fire

Protection Engineers, Boston, Massachusetts, 1997.

Hill, J.P., “Fire Tests in Ventilated Rooms: Extinguishment of Fire in Grouped Cable Trays,” EPRI

NP-2660, Electric Power Research Institute, Palo Alto, California, 1982.

Nuclear Regulatory Commission, “Fire Protection for Operating Nuclear Power Plants,” Regulatory

Guide 1.189, April 2001.

Nuclear Regulatory Commission, BTP APCSB 9.5-1, “Guidelines for Fire Protection for Nuclear

Power Plants,” May 1, 1976.

Nuclear Regulatory Commission, “Appendix A to BTP APCSB 9.5-1 - Guidelines for Fire Protection

for Nuclear Power Plants, Docketed Prior to July 1, 1976,” February 24, 1977.
1-13

Nuclear Regulatory Commission, BTP ASB 9.5-1, “Guidelines for Fire Protection for Nuclear Power

Plants,” Revision 1, March 1979.

Nuclear Regulatory Commission, BTP CMEB 9.5-1 (Formerly ASB 9.5-1), “Guidelines for Fire

Protection for Nuclear Power Plants,” Revision 2, July 1981.

Nuclear Regulatory Commission, NUREG/BR-0010, “Citizen’s Guide to U.S. Nuclear Regulatory

Commission Information,” Revision 4, August 2003.

1.13 Additional Readings

National Fire Protection Association, NFPA 805, Performance-Based Standard for Fire Protection

for Light-Water Reactor Electric Generating Plants, Quincy, Massachusetts, 2001.

Society of Fire Protection Engineers, SFPE Engineering Guide to Performance-Based Fire

Protection, Analysis and Design of Buildings, Bethesda, Maryland, 2000.

Society of Fire Protection Engineers, The SFPE Code Official’s Guide to Performance-Based

Design Review, Bethesda, Maryland, 2004.

2-1

CHAPTER 2. PREDICTING HOT GAS LAYER TEMPERATURE

AND SMOKE LAYER HEIGHT IN A ROOM FIRE

WITH NATURAL AND FORCED VENTILATION

2.1 Objectives

This chapter has the following objectives:

• Explain the different stages of a compartment fire.

• Identify the types of forced and natural ventilation systems.

• Explain how the various types of forced ventilation systems work.

• Describe how to calculate the hot gas layer temperature and smoke layer height for a fire

in a compartment with both natural and forced ventilation systems.

2.2 Introduction

In evaluating the environmental conditions resulting from a fire in an enclosure, it is essential to

estimate the temperature of the hot fire gases. These elevated temperatures can often have a

direct impact on nuclear power plant (NPP) safety. A temperature estimate is also necessary in

order to predict mass flow rates in and out through openings, thermal feedback to the fuel and other

combustible objects, and thermal influence (initiating stimulus) on detection and suppression systems.

Heat from a fire poses a significant threat to the operation of NPPs, both when the component and

equipment come in contact with heated fire gases and when heat is radiated from a distance.

2.3 Compartment Fire Growth

A compartment or enclosure fire is usually a fire that is confined to a single compartment within a

structure. Ventilation is achieved through open doors and windows, as well as heating, ventilation,

and air conditioning (HVAC) systems. Such a fire typically progresses through several stages

(or phases) as a function of time, as discussed in the next section.

2.3.1 Stages of Compartment Fires

Initially, fire in a compartment can be treated as a freely burning, unconfined fire. This treatment

is a valid approximation until thermal feedback or oxygen depletion in the compartment becomes

significant. In many ventilated spaces, the ventilation is stopped automatically under fire conditions,

either through the shutdown of fan units or the closing of fire doors and dampers. In other spaces,

however, ventilation systems may continue to operate or unprotected openings may remain open.

The course of compartment fires, and the conditions that result, depend on the following variables

(among others):

• fire heat release rate (HRR) of the combustible

• enclosure size

• enclosure construction

• enclosure ventilation
2-2

Figure 2-1 Typical Stages of Fire Development

Figure 2-2 Stages of Compartment Fire
2-3

Conceptually, compartment fires can be considered in terms of the four stages illustrated in Figures

2-1 and 2-2. The initial stage of compartment fires is the fire plume/ceiling jet phase. During this

stage, buoyant hot gases rise to the ceiling in a plume above the fire and spread radially beneath

the ceiling as a relatively thin jet. As the plume gases rise to the ceiling, they entrain cool, fresh air.

This entrainment decreases the plume temperature and combustion product concentrations, but

increases the volume of smoke. The plume gases impinge upon the ceiling and turn to form a

ceiling jet, which can continue to extend radially until it is confined by enclosure boundaries or other

obstructions (such as deep solid beams at the ceiling level).

Once the ceiling jet spreads to the full extent of the compartment, the second stage of compartment

fires ensues. During this stage, a layer of smoke descends from the ceiling as a result of air

entrainment into the smoke layer and gas expansion attributable to heat addition to the smoke

layer. The gas expansion, in turn increases the average temperature of the smoke layer. However,

the continuing entrainment of cool, fresh air into the smoke layer tends to slow this temperature

increase.

The duration of this second stage (an unventilated compartment smoke filling phase) depends on

the HRR of the fuel, the size and configuration of the compartment, the heat loss histories, and the

types and locations of ventilation openings in the compartment. In closed compartments, the

smoke layer continues to descend until the room is filled with smoke or until the fire source burns

out, as a result of either fuel consumption or oxygen depletion. In ventilated compartments, the

smoke layer descends to the elevation where the rate of mass flow into the smoke layer is balanced

by the rate of flow from the smoke layer through natural or mechanical ventilation.

The preflashover vented fire stage begins when smoke starts to flow from the compartment.

Ventilation may occur naturally through openings in compartment boundaries (such as doorways),

or it may be forced by mechanical air handling systems. The smoke layer may continue to expand

and descend during the preflashover vented fire stage.

The final stage of compartment fires, known as the postflashover vented phase, represents the

most significant hazard, both within the fire compartment and as it affects remote areas of a

building. This stage occurs when thermal conditions within the compartment reach a point at which

all exposed combustibles ignite, virtually simultaneously in many cases, and air flow to the

compartment is sufficient to sustain intense burning. During this stage, the rate of air flow into the

compartment and, consequently, the peak rate of burning within the compartment, become limited.

The ventilation is limited by the sizes, shapes, and locations of boundary openings for naturally

ventilated spaces, or by the ventilation rate from mechanically ventilated spaces. With adequate

ventilation, flames may fill the enclosure volume and result in a rapid change from a developing

compartment fire to full compartment involvement. This point is commonly referred to as

“flashover.” Flashover is the point in compartment fire development which can evolve as a rapid

transition from a slowly growing to fully developed fire. The underlying mechanism in this

phenomenon is essentially a positive feedback from the fire environment to the burning fuel. The

formation of a hot ceiling layer at the early stages of a fire leads to radiative feedback to the fuel,

which, in turn, increases the burning rate and the temperature of the smoke layer. If heat losses

from the compartment are insufficient, a sharp increase in the fire’s power (i.e., flashover) will

eventually occur.
2-4

The International Organization for Standardization (ISO) formally defines flashover as “the rapid

transition to a state of total surface involvement in a fire of combustion material within an

enclosure.” In fire protection engineering, the term is used as the demarcation point between the

preflashover and postflashover stages of a compartment fire. Flashover is not a precise term, and

several variations in its definition can be found in the literature. The criteria given usually require

that the temperature in the compartment reaches 500 to 600 °C (932 to 1,112 °F), the radiation heat

transfer to the floor of the compartment is 15 to 20 kW/m (1.32 to 1.76 Btu/ft -sec), or flames 2 2

appear from the compartment openings. In a compartment with one opening, flashover is

principally described by four stages. Specifically, the hot buoyant plume develops at the first stage

following ignition, and then reaches the ceiling and spreads as a ceiling jet during the second stage.

During the third and fourth stages, the hot layer expands and deepens, while flow through the

opening is established.

Flashover usually causes the fire to reach its fully developed state, in which all of the fuel within the

room becomes involved. However, all of the fuel gases may not be able to combust within the room

because the air supply is limited. Such an air-limited fire is commonly termed “ventilation-limited”

or “ventilation-controlled”, as opposed to a “fuel-limited” fire, which is a fire that has an ample supply

of oxygen and is limited by the amount of materials (fuel) burning.

2.3.2 Ventilation-Limited or Ventilation-Controlled Fires

A ventilation-limited or ventilation-controlled fire is one that experiences low oxygen concentration

as a result of insufficient air supply. The hot fire gases typically have nearly zero oxygen.

2.3.3 Fuel-Limited Fires

In contrast to a ventilation-limited fire, a fuel limited fire is a compartment fire in which the air supply

is sufficient to maintain combustion, but the amount of fuel that is burning limits the fire size.

2.4 Compartment Ventilation

General ventilation system design controls heat, odors, and hazardous chemical contaminants.

General ventilation can be provided by mechanical systems, by natural draft, or by a combination

of the two. Examples of combination systems include (1) mechanical supply with air relief through

louvers and/or other types of vents and (2) mechanical exhaust with air replacement inlet louvers

and/or doors. Natural ventilation is a controlled flow of air caused by thermal and wind pressure.

Mechanical or forced ventilation is accomplished with fans to create the pressure differentials to

produce the desired flows of air. Exhaust in the ventilation process that draws noxious air entrained

particulate and vapors from a compartment, collect them into ducts for transport to the outside or

to equipment that cleans the air before discharging it to the outside or returning it to the area of

origin. In a closed area, exhaust cannot operate at the flows required without having an equal

supply of makeup air available. “Makeup air” and “replacement air” are the terms commonly used

to refer to the air that has to be brought into a space to limit pressure gradients so that the exhaust

process can operate as designed. This air may be brought directly into a space via ducts or

indirectly via openings from adjacent areas. The quantity of makeup air must be of a sufficient flow

rate to allow the exhaust system to operate within its pressure differential design parameters, yet

not be so great as to create a positive pressure within the compartment.
2-5

Mechanically ventilated compartments are a common environment for fire growth in NPP structures.

A fire in a forced-ventilation compartment is markedly different than in a compartment with natural

ventilation. An important factor is that the stratified thermal hot gas layer induced by the fire in a

naturally ventilated compartment may be unstable in a forced ventilation compartment. Normally,

a ventilating system recirculates most of the exhaust air. If normal operation were to continue

during a fire, this recirculation could result in smoke and combustion products being mixed with

supply air, and the contaminated mixture being delivered throughout the ventilation zone.

To prevent this, dampers are often placed in the system. Upon fire detection in an engineered

smoke control system, the damper positions are changed so that all exhaust from the fire zone is

dumped, and 100-percent makeup air is drawn from outside the building.

The following four general types of mechanical ventilation systems are commonly encountered,

as illustrated in Figure 2-3.

Figure 2-3 Types of Mechanical Ventilation Systems
2-6

2.4.1 Definitions

• Push Systems - Push systems mechanically supply fresh (outside) air into a compartment

at the design volumetric flow rate of the system, while air expulsion occurs freely through

transfer grills, registers, or diffusers in the compartment.

• Pull Systems - Pull systems mechanically extract hot gases (smoke) from a compartment.

Pull systems are designed to extract smoke from a compartment based on the volumetric

flow rate of the system. The density of smoke is normally less than that of ambient air

because the smoke is at an elevated temperature.

• Push-Pull Systems - Push-pull systems both inject and extract air mechanically, with the

supply and exhaust fan units typically sized and configured to produce balance supply and

exhaust rates under normal operation. Push-pull systems cannot continue to operate at

their balanced design flow rate under fire conditions. If the supply and exhaust fan units

continue to inject and extract air at the same balanced design volumetric flow rates, the rate

of mass injection will exceed the rate of mass extraction because of the difference in the

densities of the supply and exhaust streams.

• Recirculation Systems - Recirculation systems typically use a single fan unit to mechanically

extract air from a space, condition it, and return it to the same space.

• Volume Flow Rate handled by the fan is the number of cubic feet of air per minute (cfm)

expressed at fan inlet conditions.

• Fan Total Pressure Rise is the fan total pressure at the outlet minus the fan total pressure

at all inlet (in. of water).

• Fan Velocity Pressure is the pressure corresponding to the average velocity determined

from the volume flow rate and fan outlet area (in. of water).

• Fan Static Pressure Rise is the fan total pressure rise diminished by the fan velocity

pressure. The fan inlet velocity head is assumed to be equal to zero for fan rating purposes

(in. of water).

2.5 Temperature

When discussing gases, temperature is a measure of the mean kinetic energy of the molecules in

a gas. Temperature defines the conditions under which heat transfer occurs. A gas temperature,

Tg, describes precisely the state of the average molecular energy in that gas. However that

description is not particularly useful for the purposes of describing the physical phenomena that are

relevant to fire science. In a broad sense, temperature can be thought of as a measure of the state

of a system. Materials behave differently at different temperatures. Water, for example, at

atmospheric pressure, is solid below 0 °C (32 °F), liquid between 0 °C (32 °F) and 100 °C (212 °F),

and gaseous above 100 °C (212 °F). Similarly, plastic materials begin to gasify at a certain

temperature. At a slightly higher temperature, they gasify enough to ignite, and at still higher

temperatures, they may self-ignite. For our purpose, then, temperature can be viewed as an

indicator of the state of an object system.
The Rankine scale is used for absolute zero in the English units. Since most fire dynamics 1

equations will be solved in SI units, it will not be discussed here.

2-7

There are standard ways to define temperature. The most common are the Fahrenheit and Celsius

scales of temperature. Related to these scales is the Kelvin absolute temperature scale .

1

The correspondence between the scales is illustrated in Table 2-1.

Table 2-1. Temperature Conversions

Original Unit Conversions

Ce C F Klsius, T Fahrenheit, T Kelvin, T

Ce Clsius, T C C - 9/5 (T ) + 32 T + 273.15

Fah Frenheit, T 5/9 (TF F - 32) - 5/9 (T + 459.7)

Ke Klvin, T TK K - 273.15 9/5 (T - 255.37) -

The difference between the relative temperature scale and its absolute counterpart is the starting

point of the scale. That is, 0 °C is equal to 273 Kelvin and each degree on the Celsius scale is

equal to 1 degree on the Kelvin scale. By contrast, the English unit temperature scale and SI

(metric) unit temperature scale differ in two main ways. Specifically, zero is defined differently in

Celsius than in Fahrenheit, and one degree Fahrenheit represents a different quantity of heat than

one degree Celsius for a given heat capacity and mass. It is important to remember that these

temperature scales are arbitrary, but they relate to important physical processes and the effect of

temperature on an object is what we are really interested in.

Table 2-2 lists the critical temperatures for different exposure conditions and the resultant effects

on humans.

Table 2-2. Critical Temperatures for Different Exposure Conditions and Effects on Humans

[Chartered Institution of Building Services Engineers (CIBSE) Guide E. With permission.]

Type and Period of Heat Exposure Temperature

°C (°F)

Effect

Radiation 185 (365) Severe skin pain

Conduction (metal) (1 second) 60 (140) Skin burns

Convection (30 minutes) 100 (212) Hyperthermia

Convection (< 5 minutes) 120 (248) Skin and lungs are burned by hot gases

Convection (<1 minute) 190 (374) Skin and lungs are burned by hot gases
2-8

In order to calculate or predict the temperatures in a compartment, a description or analytical

approximation of the fire phenomena must be created in quantitative terms. This approximation is

described in terms of physical equations for chemistry, physics, mathematics, fluid mechanics, and

heat and mass transfer, which can be solved to predict the temperature in the compartment. Such

an approximation, therefore, is an idealization of the compartment fire phenomena (i.e., ignition,

flame spread, and burning rate).

2.6 Estimating Hot Gas Layer Temperature

This section presents methods predicting the temperature achieved by the hot gas layer in an

enclosure fire; these methods are currently the most widely accepted in the fire protection

engineering literature. Nonetheless, the methods employ assumptions and limitations, which must

be understood before using any of the methods presented.

2.6.1 Natural Ventilation: Method of McCaffrey, Quintiere, and Harkleroad (MQH)

The temperatures throughout a compartment in which a fire is burning are affected by the amount

of air supplied to the fire and the location at which the air enters the compartment. Ventilationlimited fires produce different temperature profiles in a compartment than well-ventilated fires.

A compartment with a single rectangular wall opening (such as a door or window) is commonly

used for room fire experiments. They also are commonly involved in real fire scenarios, where a

single door or vent opening serves as the only path for fire-induced natural ventilation to the

compartment. The hot gas layer that forms in compartment fires descends within the opening until

a quasi-steady balance is struck between the rate of mass inflow to the layer and the rate of mass

outflow from the layer.

A complete solution of the mass flow rate in this scenario requires equating and solving two nonlinear equations describing the vent flow rate and the plume entrainment rate as a function of the

layer interface height (the layer in a compartment that separates the smoke layer from the clear

layer). If it is nonvented, the smoke layer gradually descends as the fire increases, thereby

lowering the smoke interface and (possibly) eventually filling the compartment. McCaffrey,

Quintiere, and Harkleroad (MQH) (1981) (also reported by Walton and Thomas, 1995 and 2002)

have developed a simple statistical dimensionless correlation for evaluating fire growth in a

compartment (hot gas layer temperature) with natural ventilation. This MQH correlation is based

on 100 experimental fires (from 8 series of tests involving several types of fuel) in conventionalsized rooms with openings. The temperature differences varied from T = 20 °C (68 °F) to 600 °C

(1,112 °F). The fire source was away from walls (i.e., data was obtained from fires set in the center

of the compartment). The larger the HRR , and the smaller the vent, the higher we expect the

upper-layer gas temperature to increase.
2-9

The g g a approximate formula for the hot gas layer temperature increase, T , above ambient (T - T )

is as follows:

 (2-1)

Where:

Tg g a = upper layer gas temperature rise above ambient (T - T ) (K)

 = heat release rate of the fire (kW)

Av = total area of ventilation opening(s) (m )

2

hv = height of ventilation opening (m)

hk = heat transfer coefficient (kW/m -K) 2

AT = total area of the compartment enclosing surfaces (m ), excluding area of vent opening(s). 2

The above equation can be used for multiple vents by summing the values, as follows:

where n is the number of vents, and can be used for different construction materials by summing

T

the A values for the various wall, ceiling, and floor elements.

The compartment interior surface area can be calculated as follows:

AT c c = ceiling + floor 2 (w x l )

c c + 2 large walls 2 (h x w )

c c + 2 small walls 2 (h x l )

v

 - total area of vent opening(s) (A )

AT c c c c c c v = [2 (w x l ) + 2 (h x w ) + 2 (h x l )] - A (2-2)

Where:

AT = total compartment interior surface area (m ), excluding area of vent opening(s) 2

wc = compartment width (m)

c

l = compartment length (m)

hc = compartment height (m)

Av = total area of ventilation opening(s) (m )

2
2-10

For very thin solids, or for conduction through a solid that continues for a long time, the process of

k

conduction becomes stationary (steady-state). The heat transfer coefficient, h , after long heating

times, can be written as follows:

 (2-3)

Where:

k = thermal conductivity (kW/m-K) of the interior lining

 = thickness of the interior lining (m)

This equation is useful for steady-state applications in which the fire burns longer than the time

required for the heat to be transferred through the material until it begins to be lost out the back

p

(cold) side. This time is referred to as the thermal penetration time, t , which can be calculated as:

 (2-4)

Where:

 = density of the interior lining (kg/m )

3

p

c = thermal capacity of the interior lining (kJ/kg-K)

k = thermal conductivity of the interior lining (kW/m-K)

 = thickness of the interior lining (m)

However p, if the burning time is less than the thermal penetration time, t , the boundary material

retains most of the energy transferred to it and little will be lost out the non-fire (cold) side. The heat

k p transfer coefficient, h , in this case, can then be estimated using the following equation for t < t :

 (2-5)

Where:

k c = interior construction thermal inertia [(kW/m -K) -sec] 2 2

 (thermal property of the material responsible for the rate of temperature increase)

t = time after ignition in seconds (characteristic burning time)

B py contrast, for t $ t , the heat transfer coefficient is estimated from Equation 2-3.

As indicated above, the k c parameter is a thermal property of the material responsible for the rate

of temperature increase. This is the product of the material thermal conductivity (k), the material

density ( ), and the heat capacity (c). Collectively, k c is known as the material thermal inertia.

For most materials, c does not vary significantly, and the thermal conductivity is largely a function

of the material density. This means that density tends to be the most important material property.

Low-density materials are excellent thermal insulators. Since heat does not pass through such

materials, the surface of the material actually heats more rapidly and, as a result, can ignite more

quickly. Good insulators (low-density materials), therefore, typically ignite more quickly than poor

insulators (high-density materials). This is the primary reason that foamed plastics are so
2-11

dangerous in fires; they heat rapidly and ignite in situations in which a poor insulator would be

slower to ignite because of its slower response to the incident heat flux. The thermal response

properties (k c), for a variety of generic materials have been reported in the literature. These

values have been derived from measurements in the small-scale lateral ignition and flame spread

test (LIFT) apparatus (ASTM E1321). Table 2-3 lists typical thermal properties of variety of

materials.

Table 2-3. Thermal Properties of Compartment Enclosing Surface Materials

(Klote and Milke, 2002, © ASHRAE. With permission.)

Materials Thermal Inertia

k c

(kW/m -K) -sec 2 2

Thermal

Conductivity

k

(kW/m-K)

Thermal

Capacity

c

(kJ/kg-K)

 Density

(kg/m )

3

Aluminum (pure) 500 0.206 0.0895 2710

Steel (0.5% Carbon) 197 0.054 0.465 7850

Concrete 2.9 0.0016 0.75 2400

Brick 1.7 0.0008 0.8 2600

Glass, Plate 1.6 0.00076 0.8 2710

Brick/Concrete Block 1.2 0.00073 0.84 1900

Gypsum Board 0.18 0.00017 1.1 960

Plywood 0.16 0.00012 2.5 540

Fiber Insulation Board 0.16 0.00053 1.25 240

Chipboard 0.15 0.00015 1.25 800

Aerated Concrete 0.12 0.00026 0.96 500

Plasterboard 0.12 0.00016 0.84 950

Calcium Silicate Board 0.098 0.00013 1.12 700

Alumina Silicate Block 0.036 0.00014 1.0 260

Glass Fiber Insulation 0.0018 0.000037 0.8 60

Expanded Polystyrene 0.001 0.000034 1.5 20
2-12

2.6.2 Natural Ventilation (Compartment Closed): Method of Beyler

Beyler (1991) (also reported by Walton and Thomas, 2002) developed a correlation based on a

nonsteady energy balance to the closed compartment, by assuming that the compartment has

sufficient leaks to prevent pressure buildup. For constant HRR, the compartment hot gas layer

g g a

temperature increase, T , above ambient (T - T ) is given by the following equation:

 (2-6)

Where:

 

And:

Tg g a = upper layer gas temperature rise above ambient (T - T ) (K)

k = thermal conductivity of the interior lining (kW/m-K)

 = density of the interior lining (kg/m )

3

 

c = thermal capacity of the interior lining (kJ/kg-K)

 = heat release rate of the fire (kW)

m = mass of the gas in the compartment (kg)

p

c = specific heat of air (kJ/kg-k)

t = exposure time (sec)

2.6.3 Forced Ventilation: Method of Foote, Pagni, and Alvares (FPA)

Foote, Pagni, and Alvares (FPA) (1985) (also reported by Walton and Thomas, 1995 and 2002)

developed another method, which follows the basic correlations of the MQH method, but adds

components for forced-ventilation fires. This method is based on temperature data that were

obtained from a series of tests conducted at the Lawrence Livermore National Laboratory (LLNL).

Fresh air was introduced at the floor and pulled out the ceiling by an axial fan. Test fires from 150

to 490 kW were used, producing ceiling jet temperatures from 100 to 300 °C (212 to 572 °F). The

approximate constant HRR and ventilation rates were chosen to be representative of possible fires

in ventilation-controlled rooms with seven room air changes per hour, which was roughly between

200 and 575 cfm.
2-13

The upper-layer gas temperature increase above ambient is given as a function of the fire HRR,

the compartment ventilation flow rate, the gas-specific heat capacity, the compartment surface

area, and an effective heat transfer coefficient. The nondimensional form of the resulting

temperature correlation is as follows:

 (2-7)

Where:

Tg g a = hot gas layer temperature rise above ambient (T - T ) (K)

Ta = ambient air temperature (K)

 = HRR of the fire (kW)

 = compartment mass ventilation flow rate (kg/sec)

p

c = specific heat of air (kJ/kg-K)

hk = heat transfer coefficient (kW/m -K) 2

AT = total area of compartment enclosing surfaces (m )

2

The above correlation for forced-ventilation fires can be used for different construction materials

by summ Ting the A values for the various wall, ceiling, and floor elements.

2.6.4 Forced Ventilation: Method of Deal and Beyler

Deal and Beyler (1990) (also reported by Walton and Thomas, 2002) developed a simple model

of forced ventilated compartment fires. The model is based on a quasi-steady simplified energy

equation with a simple wall heat loss model. The model is only valid for times up to 2000 seconds.

The g g a approximate compartment hot gas layer temperature increase, T , above ambient (T - T )

is given by the following equation:

 (2-8)

Where:

Tg g a = hot gas layer temperature rise above ambient (T - T ) (K)

Ta = ambient air temperature (K)

 = HRR of the fire (kW)

 = compartment mass ventilation flow rate (kg/sec)

p

c = specific heat of air (kJ/kg-K)

hk = convective heat transfer coefficient (kW/m -K) 2

AT = total area of compartment enclosing surfaces (m )

2
2-14

The convective heat transfer coefficient is given by the following expression:

 (2-9)

Where:

k = thermal conductivity of the interior lining (kW/m-K)

 = density of the interior lining (kg/m )

3

 

c = thermal capacity of the interior lining (kJ/kg-K)

t = exposure time (sec)

 = thickness of the interior lining (m)

2.7 Estimating Smoke Layer Height

When a fire occurs in a compartment, within few seconds of ignition, early flame spread can quickly

lead to a flaming, free-burning fire. If left unchecked, the fire continues to grow. Besides releasing

energy, the combustion process also yields a variety of other products, including toxic and nontoxic

gases and solids. Together, all of these products are generally referred to as the “smoke” produced

by the fire.

As the flame spreads across the fuel surface, the fire size, which can be described as the HRR,

increases. As the size increases, the radiation heat transfer from the flame to the fuel surface

increases, and this increases the burning rate. If the flame has not involved the entire surface area,

this increased fire size accelerates the flame spread. Above the flame zone, a buoyant plume is

formed. The plume entrains ambient air, which both cools the gas and increases the flow rate. In

a typical compartment, the plume strikes the ceiling and forms a ceiling jet, which in turn strikes a

wall, and the compartment begins to fill with hot smoke from the ceiling downward. The plume

continues to entrain ambient air, adding mass to the layer until it reaches the upper gas layer.

Here, as the gas layer descends, less mass is entrained into it. Thus, the amount of gas flow from

the plume is a function of the fire size and the height over which entrainment occurs.

As previously stated, the temperature and composition of gas entering the hot gas layer are driven

by the fire source and the plume. Once the hot gas enters this hot layer, it cools by losing energy

to surrounding surfaces (i.e., ceiling, walls) by conduction, and cools by radiating heat energy to

the floor and the cool gas layer near the floor. The rate of descent of the hot gas layer is driven by

the size of the compartment and the amount of mass flow from the plume. Since the plume mass

flow is a function of the height beneath the gas layer, the layer descends at a progressively slower

rate as it gets closer to the fire source.

The plume essentially mixes cool air with the combustion products, thereby increasing the total flow

into the hot gas layer, while reducing its temperature and the concentration of gases flowing into

it. The plume can only add mass to the upper layer by entrainment along the plume axis below the

hot gas layer position. Once it penetrates the hot gas layer, it entrains hot gas, helping to mix the

layer, but not increasing its depth.

One of the most important processes that occurs during the early stages of a compartment fire is

the filling of the compartment with smoke. Although the hot layer gas temperatures are relatively
2-15

low [< 200 °C (392 °F)], the composition of the smoke relative to visibility and toxicity and the

vertical position of the layer are of interest. Figure 2-4 shows this process schematically.

Figure 2-4 Smoke Filling in a Compartment Fire

2.7.1 Smoke Layer

The smoke layer can be described as the accumulated thickness of smoke below a physical or

thermal barrier (e.g., ceiling). The smoke layer is typically not a homogeneous mixture, and it does

not typically have a uniform temperature. However, for first-order approximations, the calculation

methods presented below assume homogeneous conditions. The smoke layer includes a transition

zone that is nonhomogeneous and separates the hot upper layer from the smoke-free air (i.e., two

zones).

2.7.2 Smoke Layer Interface Position

Figure 2-5 depicts the theoretical boundary (or interface) between a smoke layer and the smokefree air. In practice, the smoke layer interface is an effective boundary within a transition buffer

zone, which can be several feet thick. Below this effective boundary, the smoke density in the

transition zone decreases to zero.

2.7.3 Natural Ventilation (Smoke Filling): 

The Non-Steady-State Yamana and Tanaka Method

In a compartment with larger openings (windows or doors), there will be little or no buildup of

pressure attributed to the volumetric expansion of hot gases, with the exception of rapid

accumulation of mass or energy. Thus, for the first-order approximations, pressure is assumed to

remain at the ambient pressure. The opening flows are thus determined by the hydrostatic

pressure differences across the openings, and mass flows out of and into the compartment.

We g also assume that the upper layer density ( ), is some average constant value at all times

throughout the smoke-filling process.
2-16

Assuming a constant average density in the upper hot gas layer has the advantage that we can

form an analytical solution of the smoke-filling rate, where the HRR does not need to be constant

(that is, it can be allowed to change with time), and we can use the conservation of mass to arrive

at the expression for the smoke-filling rate. When this is done, the height of the smoke layer as a

function of time is known, and we can use the conservation of energy to check the stipulated value

o gf .

Yamana and Tanaka (1985) (also reported by Karlsson and Quintiere, 1999b) developed the

expression for the height of the smoke layer interface, z, in terms of time, as follows:

 (2-10)

Where:

z = height (m) of the smoke layer interface above the floor

 = heat release rate of the fire (kW)

t = time after ignition (sec)

Ac = compartment floor area (m )

2

hc = compartment height (m)

And:

k = a constant given by the following equation:

 (2-11)

Where:

g

 = hot gas density kg/m3

a

 = ambient density = 1.20 kg/m3

g = acceleration of gravity = 9.81 m/sec2

p

c = specific heat of air = 1.0 kJ/kg-K

Ta = ambient air temperature = 298 K.

Substituting the above numerical values in Equation 2-11, we get the following expression:

 (2-12)

Where densi gty of the hot gas ( ), layer is given by:

 (2-13)

Where:

g

 T = hot gas layer temperature (K) calculated from Equation 2-1
2-17

Calculation Procedure

g

(1) Calculate from Equation 2-13.

(2) Calculate the constant k from Equation 2-12.

(3) Calculate the smoke layer height (z) at the some time (t) from Equation 2-10 given HRR.

2.8 Data Sources for Heat Release Rate

When an object burns, it releases a certain amount of energy per unit of time. For most materials,

the HRR of a fuel changes with time, in relation to its chemistry, physical form, and availability of

oxidant (air), and is ordinarily expressed as kW (kJ/sec) or Btu/sec and denoted by (1,000 kW

= 1 MW) (1 BTU/sec = 1.055 kW).

Figure 2-5 illustrates the general features of typical HRR histories. HRR commonly demonstrates

an acceleratory growth stage, which may follow an induction stage of negligible growth. Objects

may or may not exhibit the period of fairly steady burning illustrated in Figure 2-5 (a); this depends

on whether fuel burnout begins after the fuel surface is fully involved. Materials that do not begin

to burn out before the fuel surface is fully involved (peak HRR) demonstrate the fairly steady

burning period exhibited in Figure 2-5 (a) until burnout begins; materials that begin to burn out

before the peak HRR is achieved are characterized by heat release curves with distinct peaks, as

illustrated in Figure 2-5 (b). In either case, at some time following attainment of peak HRR, a decay

stage associated with fuel burnout usually occurs. This decay stage frequently gives way to a tail

stage of relatively low HRR. This tail stage, which may persist for an extended time, is normally

attributable to the glowing combustion that follows flaming combustion for char-forming products.

The total energy released by a material is equal to the area under the time-HRR curve. This area

is influenced by the energy released during the tail stage, which may contribute a considerable

portion of the total energy released, but at such a slow rate that it does not constitute the significant

hazard.
2-18

Figure 2-5 General Representation of Heat Release Rate Histories for a Fuel Package
2-19

2.9 Identification of Fire Scenario

The first step in an FHA is to identify which target(s) to evaluate within an enclosure or

compartment. Normally, the target is a safety-related component that is being evaluated for a

particular scenario. However, if exposed, intervening combustibles exist between the fire source

and the safety-related component, they can become the targets for further evaluation.

Electrical cables typically serve as the primary target for most NPP analyses. The nuclear industry

has defined two general types of electrical cables, referred to as IEEE-383 qualified and

unqualified. These terms refer to cables that either pass or fail the IEEE-383 fire test standard,

respectively. A damage threshold temperature of 370 °C (700 °F) and a critical heat flux of

10 kW/m (1 Btu/ft -sec) have been selected for IEEE-383 qualified cable. A damage threshold 2 2

temperature of 218 °C (425 °F) and a critical heat flux of 5 kW/m (0.5 Btu/ft -sec) have been 2 2

selected for IEEE-383 unqualified cable. These values are reported in several studies, including

NUREG/CR-4679, Electrical Power Research Institute (EPRI), “Fire-Induced Vulnerability

Evaluation (FIVE) Methodology,” and the U.S. Department of Transportation (DOT) study reported

in “Combustibility of Electrical Wire and Cable for Rail Rapid Transient Systems,” DOT-TSC-UMAT83-4-1, May 1983.

The second step in an FHA is to identify the location of credible exposure fire sources relative to

the target being evaluated. Exposure fires involving transient combustibles are assumed to have

an equal probability of occurring anywhere in a space, while exposure fires involving fixed

combustibles are assumed to occur at the site of the fixed combustible. Since the hazard is greater

when a fire is located directly beneath a target, this placement is evaluated for scenarios involving

exposure fires with transient combustibles. For fixed combustibles, the actual geometry between

the source and the target is evaluated to determine whether the target is located in the fire plume

region.

Representative unit HRR values for a number of fuels present in the NPP (e.g., electrical cables,

electrical cabinets, flammable/combustible liquids, and transient combustibles) have been

measured and reported in various reports by Lee (1985), Nowlen (1986 and 1987), Chavez (1987),

and Babrauskas (1991). Flammable/combustible liquid spill fires and trash fires are the most

commonly postulated transient fuel exposure fires in NPPs. Electrical cable fires and electrical

cabinet fires are the most commonly postulated fixed fuel fires. Tables 2-4 through 2-10 show the

HRR and other data for common fixed and transient combustible materials found in NPPs.
2-20

Table 2-4. Measured Heat Release Rate Data for Cable Jacketing Material

(Lee, 1981)

Fuel HRR per Unit

Area

(kW/m )

2

Heat of

Combustion

Hc (kJ/kg)

PE/PVC (Polyethylene/Polyvinylchloride) 590 24,000

XPE/FRXPE

(Crosslinked Polyethylene/Fire Retardant

Crosslinked Polyethylene)

475 28,300

XPE/Neoprene 300 10,300

PE, Nylon/PVC, Nylon 230 9,200

TefzelTM - ETFE

(Ethylenetetrafluoroethylene)

100 3,200

Table 2-5. Measured Heat Release Rate Data for Electrical Cabinets

(Nowlen, 1986 and 1987)

Fuel Peak HRR*

(kW)

Electrical Cabinet Filled with IEEE-383 Qualified Cables

(Vertical doors open)

 55

Electrical Cabinet Filled with IEEE-383 Qualified Cables

(Vertical doors closed)

No data 

Electrical Cabinet Filled with IEEE-383 Unqualified Cables

(Vertical doors open)

1,000

Electrical Cabinet Filled with IEEE-383 Unqualified Cables

(Vertical doors closed, vent grills only)

185

*Note: HRR contributions in the electrical cabinet are based solely on the cable insulation

material, and neglect the energy release based on the current (amperes squared

multiplied by time.)
2-21

Table 2-6. Measured Heat Release Rate Data for Transient Combustible Materials

(Flammable/Combustible Liquids)

Fuel HRR per Unit Area

(kW/m )

2

Diesel oil 1,985

Gasoline 3,290

Kerosene 2,200

Transformer oil 1,795

Lube oil lubrication

(used in reactor coolant pump (RCP) motors and

turbine)

For lubricating oil, use HRR of

transformer oil. Lubricating oil has

burning characteristics similar to

transformer oil. 

Table 2-7. Measured Heat Release Rate Data for Transient Combustible Materials

(Trash) (Lee, 1985)

Fuel Peak HRR

(kW)

9.1 kg computer paper crumpled up in two plastic trash bags 110

11.4 kg rags, 7.7 paper towels. 5.9 kg plastic gloves and taps, and

5.9 kg methyl alcohol, mixed in two 50-gallon trash bags

120

13.6 kg computer paper crumpled up and divided in two 7.5 kg (50

gallon) plastic trash cans 

110

4.6 kg crumpled up computer paper and 31.8 kg folded computer

paper, evenly divided into two bags

40
2-22

Table 2-8. Measured Heat Release Rate Data

for Transient Combustible Materials (Plywood and Wood Pallet)

(Karlsson and Quintiere, 1999a, © CRC Press, LLC. With permission.)

Fuel HRR per Unit Area

(kW/m )

2

Douglas fir plywood 124

Fire-retardant treated plywood 81

Wood pallets, stacked 11⁄2 ft high 1,420

Wood pallets, stacked 5 ft high 3,970

Wood pallets, stacked 10 ft high 6,800

Wood pallets, stacked 16 ft high 10,200 

Table 2-9. Ignition Thresholds (Pilotless within 30 seconds)

(Naval Ship’s Technical Manual, S9086-S3-STM-010/CH-555, 1993) 

Material Hot Air (Oven Effect)

°C (°F)

Hot Metal Contact

(Frying Pan Effect)

(kW/m )

2

Radiant Heat Flux

(kW/m )

2

Paper 230 (450) 250 (480) 20

Cloth 250 (480) 300 (570) 35

Wood 300 (570) 350 (660) 40

Cables 375 (700) 450 (840) 60

Table 2-10. Thermal Effects on Electronics

(Naval Ship’s Technical Manual, S9086-S3-STM-010/CH-555, 1993) 

Temperature

°C (°F)

Effects

50 (120) Computer develop faults

150 (300) Permanent computer damage

250 (480) Data transmission cable fail
2-23

2.10 Assumptions and Limitations

The methods discussed in this chapter have several assumptions and limitations.

The following assumptions and limitations apply to all forced and natural convection situations:

(1) These methods best apply to conventional-size compartments. They should be used with

caution for large compartments.

(2) These methods apply to both transient and steady-state fire growth.

(3) The HRR must be known; it does not need to be constant, and can be allowed to change

with time.

(4) Compartment geometry assumes that a given space can be analyzed as a rectangular

space with no beam pockets. This assumption affects the smoke filling rate within a space

if the space has beam pockets. For irregularly shaped compartments, equivalent

compartment dimensions (length, width, and height) must be calculated and should yield

slightly higher layer temperatures than would actually be expected from a fire in the given

compartment.

(5) These methods predict average temperatures and do not apply to cases in which

predication of local temperature is desired. For example, this method should not be used

to predict detector or sprinkler actuation or the material temperatures resulting from direct

flame impingement. 

(6) Caution should be exercised when the compartment overhead are highly congested with

obstructions such as cable trays, conduits, ducts, etc. 

(7) A single heat transfer coefficient may be used for the entire inner surface of the

compartment.

(8) The heat flow to and through the compartment boundaries is unidimensional ( i.e., corners

and edges are ignored, and the boundaries are assumed to be infinite slabs).

(9) These methods assume that heat loss occurs as a result of mass flowing out through

openings. Consequently, these methods do not apply to situations in which significant time

passes before hot gases begin leaving the compartment through openings. This may occur

in large enclosures (e.g., turbine building), where it may take considerable time for the

smoke layer to reach the height of the opening.

The following assumptions and limitations apply only to natural convection situations:

(10) The correlations hold for compartment upper layer gas temperatures up to approximately

600 °C (1,112 °F) only for naturally ventilated spaces in which a quasi-steady balance

develops between the rates of mass inflow and outflow from the hot gas layer.

(11) These correlations assume that the fire is located in the center of the compartment or away

from the walls. If the fire is flush with a wall or in a corner of the compartment, the MQH

correlation is not valid with coefficient 6.85.

(12) The smoke layer height correlation assumes an average constant value of upper layer

density throughout the smoke-filling process.

(13) The correlation does not allow the vent to be placed in the ceiling.
2-24

(14) At the EPRI Fire Modeling Workshop, August 26, 2002 in Seattle, Washington, Mark Salley

asked Professor James G. Quintiere (one of the authors of the MQH method) what limits

apply to compartment size when using the MQH equation. Professor Quintiere replied that

the correlation will work for any size compartment since it is a dimensionless equation.

Professor Quintiere also stated that should be limited by the following expressions:

Where:

mass loss rate of fuel (kg/sec)

Hc = heat of combustion (kJ/kg)

Av = area of ventilation opening (m )

2

hv = Height of ventilation opening (m)

The following assumptions and limitations apply only to forced convection situations:

(15) These correlations assume that the test compartment is open to the outside at the inlet, and

its pressure is fixed near 1 atmosphere.

(16) These correlations do not explicitly account for evaluation of the fire source.

(17) These correlations assume that the fire is located in the center of the compartment or away

from the walls. If the fire is flush with a wall or in a corner of the compartment, the Foot,

Pagni, and Alvares (FPA) correlation is not valid with coefficient 0.63.

2.11 Required Input for Spreadsheet Calculations

The user must obtain the following values before attempting a calculation using the natural or

forced ventilation spreadsheets:

(1) Compartment width (ft)

(2) Compartment length (ft)

(3) Compartment height (ft)

(4) Interior lining material thickness (in)

(6) Fire heat release rate, HRR (kW)

The user must obtain the following values before attempting a calculation using the natural

ventilation spreadsheets:

(7) Vent width (ft)

(8) Vent height (ft)

(9) Top of vent from floor (ft)

The user must obtain the following values before attempting a calculation using the forced

ventilation spreadsheets:

(10) Forced ventilation rate (cfm)
2-25

2.12 Cautions

(1) Use the appropriate spreadsheet (02.1_Temperature_NV.xls, 02.2_Temperature_FV.xls,

or 02.3_Temperature_CC.xls) in the CD ROM for calculation.

(2) Make sure to input values using correct units.

(3) The smoke layer height is a conservative estimate and is only intended to provide

an indication of where the hot gas layer is located. Calculated smoke layer heights below

the vent height are not creditable since the calculation does not account for smoke exiting

the vent!

2.13 Summary

Determination of hot gas layer temperatures and smoke layer height associated with compartment

fires provides a means of assessing an important aspect of fire hazard, namely the likelihood of

hazardous conditions when structural elements are in danger of collapsing, and the thermal

feedback to fuel sources or other objects.

When doors and/or windows provide the air for the fire, natural ventilation occurs, and the MQH

correlation applies to the prediction of hot gas temperature. The correlation is relatively

straightforward, and it yields reasonable results when applied to most situations. Specifically, the

correlation gives the temperature increase of the hot gas layer as a function of three primary

variables:

(1) fire size ( , HRR)

k T (2) energy losses to the walls (h , A )

v v (3) energy loss through vents (A ph )

Forced ventilation can have a significant effect on fire growth, the temperature profile in the

compartment, the spread of toxic fire gases, and the descent of the hot gas layer in a multi-room

building. The magnitude of this effect, of course, depends on the HRR of the combustibles and the

amount and configuration of the forced ventilation. Depending on the arrangement of the supply

and exhaust vents, forced ventilation affects the compartment’s thermal environment and sensitive

equipment, as it relates to the descent of the hot gas layer. For situations involving forced

ventilation, the FPA correlation is applied to the prediction of hot gas temperature. Specifically the

FPA correlation gives the temperature increase of the hot gas layer as a function of three primary

variables:

(1) fire size ( , HRR)

k T (2) energy losses to the walls (h , A )

p a (3) energy loss through vents ( c T )

The depth (or height) of the growing smoke layer increases with time, but it does not change once

the smoke layer has reached equilibrium. Unsteady fires do not have a plateau or upper limit for

the rate of heat release. In addition, unsteady fires may have a less rapid buildup of pressure. One

approach is to relate the interface of a growing smoke layer for an unsteady fire to a t fire profile. 2
2-27

Klote, J.H., and J.A. Milke. Principles of Smoke Management, American Society of Heating,

Refrigerating and Air-Conditioning Engineers, Inc., (ASHRAE), and Society of Fire Protection

Engineers (SFPE), ASHRAE Special Publication, 2002.

Lee, B.T., “Heat Release Rate Characteristics of Some Combustibles Fuel Sources in Nuclear

Power Plants,” NBSIR 85-3195, U.S. Department of Commerce, National Bureau of Standards

(NBS), Washington, DC, July 1985.

McCaffrey, B.J., J.G. Quintiere, and M.F. Harkleroad, “Estimating Room Temperature and

Likelihood of Flashover Using Fire Test Data Correlation,” Fire Technology, Volume 17, No. 2, pp.

98–119, 1981.

Naval Ship’s Technical Manual, Chapter 555, “Shipboard Firefighting,” Revision 1, S9086-S3-STM010/CH-555, Commander, Naval Sea Systems Command, June 1993.

Nowlen, S.P., “Heat and Mass Release for Some Transient Fuel Sources Fires: A Test Report,”

NUREG/CR-4680, U.S. Nuclear Regulatory Commission, Washington, DC, October 1986.

Nowlen, S.P., “Quantitative Data on the Fire Behavior of Combustible Materials Found in Nuclear

Power Plants: A Literature Review,” NUREG/CR-4679, U.S. Nuclear Regulatory Commission,

Washington, DC, February 1987.

“The Institute of Electrical and Electronics Engineers, IEEE-383 Standard for Type Test of Class

1E Electric Cables, Field Splices, and Connection for Nuclear Power Generating Station,”

ANSI/IEEE Std. 383-1974, New York, 1974.

Walton, W.D., and P.H. Thomas, “Estimating Temperatures in Compartment Fires,” Section 3,

Chapter 3-6, SFPE Handbook of Fire Protection Engineering, 2 Edition, P.J. DiNenno, Editor-in- nd

Chief, National Fire Protection Association, Quincy, Massachusetts, 1995.

Walton, W.D., and P.H. Thomas, “Estimating Temperatures in Compartment Fires,” Section 3,

Chapter 6, SFPE Handbook of Fire Protection Engineering, 3 Edition, P.J. DiNenno, Editor-in- rd

Chief, National Fire Protection Association, Quincy, Massachusetts, 2002.

Yamana, T., and T. Tanaka, “Smoke Control in Large Spaces, Part 1: Analytical Theories for Simple

Smoke Control Problems,” Fire Science and Technology, Volume 5, No. 1, 1985.
2-26

2.14 References

ASTM E1321-97a, “Standard Test Method for Determining Material Ignition and Flame Spread

Properties,” ASTM Fire Test Standard, Fifth Edition, American Society of Testing and Materials,

West Conshohocken, Pennsylvania, pp. 1061–1076. 1999.

Babrauskas, V., R.D. Peacock, E. Braun, R.W. Bukowski, and W.W. Jones, “Fire Performance of

Wire and Cable: ReactionntonFire—Tests A Critical Review of the Existing Methods and of New

Concepts,” NIST Technical Note 1291, U.S. Department of Commerce, National Institute of

Standards and Technology (NIST), Building and Fire Research Laboratory (BFRL), Gaithersburg,

Maryland. 1991.

Beyler, C.L., “Analysis of Compartment Fires with Overhead Forced Ventilation,” Fire Safety

Science, Proceeding of the 3 International Symposium, International Association of Fire Safety rd

Science (IAFSS), Cox and Langford, Editors, Elsevier Applied Science, New York, pp. 291-300,

1991.

Chavez, J.M., “An Experimental Investigation of Internally Ignited Fires in Nuclear Power Plant

Control Cabinets: Part 1: Cabinet Effects Tests,” NUREG/CR-4527, Volume 1, U.S. Nuclear

Regulatory Commission, Washington, DC, April 1987.

CIBSE Guide E, Fire Engineering, The Chartered Institution of Building Services Engineers,

London, p. 9–10, February 1997.

Deal, S., and C.L. Beyler, “Correlating Preflashover Room Fire Temperatures,” SFPE Journal of

Fire Protection Engineering, Volume 2, No. 2, pp. 33–48, 1990.

Drysdale, D.D., An Introduction to Fire Dynamics, Chapter 9, “The Pre-Flashover Compartment

Fire,” 2 Edition, John Wiley and Sons, New York, pp. 291–324, 1998. nd

EPRI TR-100370, “Fire-Induced Vulnerability Evaluation (FIVE),” Final Report, Electrical Power

Research Institute, Palo Alto, California, April 1992.

EPRI Fire Modeling Workshop: An Introduction to Fire Modeling in Nuclear Power Plant

Applications, Course Handouts and Discussion with Professor J.G. Quintiere, Seattle, Washington,

August 26–27, 2002.

Foote, K.L., P.J. Pagni, and N.L. Alvares, “Temperatures Correlations for Forced-Ventilated

Compartment Fires,” Fire Safety Science-Proceedings of the First International Symposium,

International Association of Fire Safety Science (IAFSS), Grant and Pagni, Editors, Hemisphere

Publishing Corporation, New York, pp. 139–148, 1985.

Karlsson, B., and J.G. Quintiere. Enclosure Fire Dynamics, Chapter 3, Energy Release Rates,”

CRC Press LLC, New York, p. 42, 1999a.

Karlsson, B., and J.G. Quintiere. Enclosure Fire Dynamics, Chapter 8, “Conservation Equations

and Smoke Filling,” CRC Press LLC, New York, p. 206, 1999b.
2-28

2.15 Additional Readings

Cote, A.E., and P. Bugbee, Principle of Fire Protection, 2 Edition, National Fire Protection nd

Association, Quincy, Massachusetts, 1988.

Cote, A.E., Fundamentals of Fire Protection, National Fire Protection Association, Quincy,

Massachusetts, 2004.

Friedman, R., Principles of Fire Protection Chemistry and Physics, 3 Edition, National Fire rd

Protection Association, Quincy, Massachusetts, 1998.

Fire Dynamics Course Guide, Federal Emergency Management Agency (FEMA), United States Fire

Administration (USFA), National Emergency Training Center, Emmitsburg, Maryland, 1995.

Harper, C.A., Editor-in-Chief, Handbook of Building Materials for Fire Protection, McGraw-Hill

Companies, New York, New York, 2004.

Icove, D.J., and J.D. DeHaan, Forensic Fire Science Reconstruction, 1 Edition, Pearson Education st

Inc., Upper Saddle River, New Jersey, 2004.

Janssens, M.L., An Introduction to Mathematical Fire Modeling, 2 Edition, Technomic Publishing nd

Company, Inc., Lancaster, Pennsylvania, 2000.

Quintiere, J.G., Principles of Fire Behavior Chapter 9, “Compartment Fires,”, Delmar Publishers,

Albany, New York, pp. 169–195, 1997.

Quinitiere, J.G., “A Simple Correlation for Predicting Temperature in a Room Fire,” NBSIR 83-2712,

National Bureau of Standards (NBS), U.S. Department of Commerce, Washington, DC, June 1983.

Quintiere, J.G., and B.J. McCaffrey, “The Burning of Wood and Plastic Cribs in an Enclosure:

Volume 1,” NBSIR 90-2054, National Bureau of Standards (NBS), U.S. Department of Commerce,

Washington, DC, November 1980.

Rasbash, D.J., G. Ramachandran, B. Kandola, J.M. Watts, and M. Law, Evaluation of Fire Safety,

John Wiley & Sons, Ltd., West Sussex, England, 2004.

SFPE Engineering Task Group, SFPE Engineering Guide to Fire Exposures to Structural Elements,

Society of Fire Protection Engineers, Bethesda, Maryland, May 2004.
2-29

Example Problem 2-1: Compartment with Natural Ventilation

2.16 Problems

2.16.1 Natural Ventilation

Example Problem 2.16.1-1

Problem Statement

Consider c c c a compartment that is 15 ft wide x 15 ft long x 10 ft high (w x l x h ), with a simple vent

v v that is 4 ft wide x 6 ft tall (w x h ). The fire is constant with an HRR of 500 kW. Compute the hot

gas layer temperature in the compartment and smoke layer height at 2 minutes assuming that the

compartment interior boundary material is (a) 1 ft thick concrete and (b) 1.0 inch thick gypsum

board. Assume that the top of the vent is 6 ft.

Solution

Purpose:

For two different interior boundary materials determine following:

g

(1) The hot gas layer temperature in the compartment (T ) at t = 2 min after ignition

(2) The smoke layer height (z) at t = 2 min after ignition

Assumptions:

(1) Air properties (ambient) at 77 °F (25 °C)

(2) Simple rectangular geometry (no beam pockets)

(3) One-dimensional heat flow through the compartment boundaries

(4) Constant heat release rate (HRR)

(5) The fire is located at the center of the compartment or away from the walls
2-30

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) For concrete: 02.1_Temperature_NV.xls (click on Temperature_ NV Thermally Thick)

(b) For gypsum board: 02.1_Temperature_NV.xls (click on Temperature_ NV Thermally

Thin)

Note: Since concrete thickness is greater than one inch, it is necessary to use the

correlations for thermally thick material. However, since the gypsum board thickness

is equal to 1 inch, it is necessary to use correlations for thermally thin material.

FDT Input Parameters: (for both spreadsheets) s

c

- Compartment Width (w ) = 15 ft

c

- Compartment Length (l ) = 15 ft

c

- Compartment Height (h ) = 10 ft

v

- Vent Width (w ) = 4 ft

v

- Vent Height (h ) = 6 ft

T

- Top of Vent from Floor (V ) = 6 ft

- Interior Lining Thickness (*) = 12 in.(concrete) and 1 in. (gypsum board)

a

- Ambient Air Temperature (T ) = 77 F

°

p

- Specific Heat of Air (c )= 1 kJ/kg-K

- Material: Select Concrete and Gypsum Board on the respective FDTs

- Fire Heat Release Rate = 500 kW

- Time after ignition (t) = 2 min

Results*

Interior Boundary

Material

Ho gt Gas Layer Temperature (T )

°C (°F)

(Method of MQH)

Smoke Layer Height (z)

z m (ft)

(Method of Yamana and Tanaka)

Concrete 147 (296) 1.83 (6.00)

T

(smoke exiting vent, z < V )

Gypsum Board 218 (425) 1.83 (6.00)

(compartment filled with smoke

*see spreadsheet on next page at t = 2 min
2-31

Spreadsheet Calculations

(a) Boundary Material: Concrete

FDT : 02.1_Temperature_NV.xls s

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11~1·)1 LIU1g n tt;H $$ 0 

Af,1BIEIIT COIIDrTO IIS 

.. :., ... bl! • t .:..t n mp~ •atu~ cr,) 

ll~lbl liUUtThPII lll ~ l1h i); pc) 

''~'•" uu•g ThPIIa tc o•d •CUJitf ;J.) 11~1·)1 Lt•t• g~ ~ HMt@ 

··~f·)f LIUUI OU$l</ ) 

""'I· 15.00 ' 

10.00 ' 

4.00 ' 

0.00 ' 

6.00 ' 

12.00 " 

77.00!,. 

.lllr.' "' 

:111.1:1"' 

.... , ... ,~ ... ll~m 

II:Jl.l:ln• 

to d&llr&d PHI~flil i11HO 

tl& •&l&c11on 
2-32

FIRES PECIFK:ATIOIIS 

METHOD OF McCAFFREY, QUINTIERE, AND HARKLEROAD(MQH) 

500.00t'"' 91 11at~ 

"-'''*""'"'" ZN'I: X.IOI'II<I<>t olf,.. ~...,,<m,.t"CC,,....,JI :1" btl•ll• llllllle l'>ol" :t.' lll 

., • 6.85 fl /,'. .) ') f'-•••)1 V\' ~ te 11 • T11 - T.,• 11 p~ll.l 19<1> te111pe otm Ita .. )W~ <rllbl!•t (~ 

a - hatfHMH ra' ~ Ill! ;_t;W) 

A,• ateaOT1JU1JI.10H OpU 119 {II') 

•• • h.;JU !J~ •111.10,_ cpu • 9 ~~) 

co ~CU.I? hat 1JaUYH COHJI::IHt ;_I;WJII _. ~ 

A• • bt.l <l ~<l OT ~ C0111p<tl111~ ·t~ •c t l$119 $I !TaO: bOI •daft$ Ud<ll19 <liM !J •t p~ • . 9$ {II') 

ArU OTW n1111UOO Cp$OIIl}l O'IICUIIIUOO 

.:.,. ;,.w:;, (•.) 

~te .o\,• ateaOT1JU1JI.10H OpU I19 {II') 

w. • vutwtiQ ~~) 

• · ~ •t ~~ ·t ll) 

.:.., - 2.2$ ...... 

llHnnal ~n$b'\'1U n 11m$ OtlculaUon 

1.- (Pcvt) ~ar 

V\ ~ te \> ·U~PII<t pU~1Ja1JH 1211 ~ ¢) 

P •ll~f.)fC0" 1JIC1JH ~Uit/ i);<l,fll ) 

II~ fbi co•, tne1J,. ~atC<l:<.l lt{ t;g-~ 

t; •ll~f.)fC0" 1JIC1),_ QUII<tiCOUIICUJl{ $WAll-~ 

;; • II' lbiCO"tlle1J,_ Q•:t:H $$ \Ill) 

t • ~ liU$ ,.c H$ilt Th'l n t fer CO$ me I$Ot OtiC UIIIUOO 

. , . 1Ji):pCI\ Dlt<t 0 1 i);P) TOft>\, 

V\• ~ te • · · Hat1Jawt:l co~m t •t :V lY ~ 

t pc • •~••"co"tnctb• ~hllalll ~ 1tt1 ;_t;W.tll .. ~ .. ;~c 

Gi ~ lll<tlpiCt=* lt'{ OThl<l~flliiUpO"bt 'bf ~ I~ OT~III pUatl te fh) 

t•thl~ ar.••;~•tb• ($ ¢) 

SH t I=* bW Dll~$ l it 

ArU Of COmpartm$1lt EnCIOtiO}l SUI1\'IC$ BoUIY.Iill1$ t 

A, • (2;,.W,X 1) + 2(. ,X W) + 2(. , X b) - A, 

~ te ,:., , • bt.l <ll~<l OT ~ C0111p<t1111~ ·t~ •c t •$119 $lltl0: bOI •daft$ UC. <III9 ar~a OT !J •t =* • . 9$ {II') 

w. - o:tllpa lllll ~ •twtn• ~~) 

I· • O:tllpa lbll ~ •t h 9U {II) 

. , COIII P,'II111~ •U H;J II) 

A, • ate <I !J~ •U1.11J) • 01=* •119 {II') 

.:.., - ~$ 2 Ill .. 

a:m plr1m$nt Hot Gu LayHnmp$rntl.lr$ W11lllaturnl W n11a Uon 

~~ · 6.85 fl .. /,'. .) ') f'-•••)1 

~~ · ~~ 1.., 

T11 • +T., 
2-33

lr!III!IM 

11m~ After 1 ll1on t h, ... T, T, T, 

~ ..... ) ~ C. A0 14 !10 .i "" rF> 

' (+.!)0 - - l~$.(1(1 l$.00 (7.(1(1 

1 " (1.22 10$.$4 40U4 1$$.$4 172.01 

' "' .1~ UH1 41H1 141i ~1 l~UO 

' "' 0.1$ 1$0. 11 42$. 11 155.11 $11.20 

' "' 0. 11 uuo 4$4.$0 1~1.50 $22.70 

' "' 0.10 14U7 43'U7 I~U7 $$2.01 

" "' 0.07 153.02 457 .Ol ISUl $U.24 

" "' 0~ 170. 14 41i$.14 1~5.14 $U.H 

" 1200 0.05 17$.$0 4."UO 20$.$0 $~$.$0 

" 1500 0.04 1$5.2~ J$ $.2~ (1.2~ 41U7 

" 1$00 0.04 1~0.~$ JSUS l iUS 420.H 

" 1 100 0.04 1~5.35 .&$$.3$ 120 ~5 423.71 

" 1400 0.0$ lOU~ .&$$.$~ 12$.$~ 4$ ~4 

" 1700 0.0$ lOU$ 502.$$ l2U$ .a.u. ~ 

" $000 0.0$ lOU$ SOU$ UUS 451.$1 

55 $$00 0.0$ l 11.2$ SOU$ UUS 457.$0 

" $~00 0.0$ l 1U7 512.$7 UU7 4ii .$ ~ 

1-bt ll:ls l.aye' Terrpe131:u-e 

Nalur3 \krdilalion (MOH Method) 

500 

E40o 

~ 300 

~ 200 

~ {!!. 100 

0 

0 10 20 30 4) 50 60 

Time lfnin) 
2-34

ESTIMATING SMOKE LAVER HEIGHT 

METHOD OF VAMA.NAANDTAI~ AKA 

o 

11\!Hif 

\I'M) + (Irl )) 

: - u nd.t L\,'tl l tl)l t f•) 

0 •lt<ltlt lt<IU In Oftlt 111! f.W} 

1 • UU 11'1 I !)1 l tll (ltC) 

I • (JI)IMJ))ItU 1tlt1Ji t .. ) 

A • OOMI)~fl tnKIU IU fill) 

I. • OI OOU1illltg ttl 1)¥1. • 0,0:6/p 

, • IOC9)1 Q,11 dt U~f9'- ) 

, l g l't• .,. , • )01' 

T - IOC9<)1 D..t l ._ptllel l! (.t) 

O.Cll,..tni iiN OkUIIIOn 

A • tw')(l) 

~ A flt fDOfM.Jfl ) 

W • W.p.l .... ltWI:Ji fl) 

I • OCMp.l .... IU "'JI .. ) 

A. - 2Ut M 

tkltG•• un' Otn •l\' O lcUI:.IOn 

, - ..,. 0 11C: UI310n 110rCOn1 tlnl t<i 

I. - OD:'6ft 

SmoU Gil 1 U Jtr Htl(llltW tl 11 \ll'lU Vtntl;'l110n 

: - (•':!1.0 f .)A, 1 + {Ill ) 

111!1111 Caution! The m::~ke l ayw height I s • oonservati~ esti mote and is only 

intended to pro\tde an lndiclllon W"lere the: hot gas layer is located. Calc:ulcted 

smo Ice I ayer hli ght bll ow the \.9'll height are not credit able si roe the calculati en 

is net aooountlngfor the srnoke exiting the 'M"It. 

nmt "' COmtmtll! ) Smol!t Layer t Smol!t Laytrh$lght 

illl , , iln ) . "W Io- ~ z (II) !<I\ 

0 1.1& o.ou 3.0$ 10.00 

1 0.17 0.017 1.83 00 

o.u o.no 1.83 00 ........, Oo~2 1.83 ~.00 

4 0.11 O.OU I.U ~.00 

5 0.10 0.035 I.U ~.00 

10 0.77 0.031 I. IS 00 

15 o.u 0. 10 I I. IS ~.00 

0.74 O. IOS I. IS ~.00 

'" I.U 00 

" 0.72 0. 105 I.U ~.00 

" 011 0.10' US 00 

.. tJI t.to7 US .... .. tJt ..... US . .. It tJt .... , 1.1$ ... --.:u --.-;;; u-s ... .. t .U t .llt ,_., ... 

CA UTO II: SMOKE IS EXrTIIIG OUTVEIIT 

UTO II: SI,10 KE IS EXrTIIIG OUTVEIIT 

UTIJ it Sl.tOKE IS EXrTIIIG OUTVEIIT 

UTIJ U: Sl.tOKE IS EXrTIIIG OUTVEIIT 

UTIJ it Sl.tOKE IS EXrTIUG OUTVEIIT 

UTIJ i t Sl.tOKE IS EXrTIUG OUTVEIIT 

UTIJ i t Sl.tOKE IS EXrTIUG OUTVEUT 

UTI:)It Sl.tOKE IS EltrTIUG OUTVEUT 

UTI:)It Sl.tOKE IS EXrTIUG OUTVEUT 

UTI:)It UAOKE IS EXITIUG OUTVEUT 

UTI:)It CUOKE IS EXITIUG OUTVEUT 

UTOit $UQt(E IS EXITIItG OUT VEUT 

UTOH: $UQt(E J$ EXITIItG OUTVEUT 

T~tt SUOKE J$ EXITI.O OUTVEIIT 

un ) tt Ulote E tJ EX ITitG OUT VVIT 

UTI)tt SllotCE IS El lllltG OUTW IT 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

leA 

leA 

leA 

leA 

b 

b 

b 
2-35

Smoke Layer Height 

NaturaiVentilation (Method ofYamana and Tan,. a) 

12 

~ 10 0 

~ 

~ 

8 

E 6 ~ l! 4 

·~ 2 :r 

0 

0 10 20 30 40 

Time(min) 

.. ~ .. WJ~ ca llatDU ar~ baad oa piiiC.)h <IH ~tt ~d . 1U S FP E Haad)Cd; OT Fh 

Pro' C1),_ EagltHIIIg, f" 6:11ba, 1002. 

5) 

c a•:II.1\Du ate b.'IHd oa o:rtn a sHrll pO' u a ad a~~ "hrutlhlltllms. ~ r~H be oTHc• 

ca •laO,. , mayor mar aot a~~ r~a. abl? pr~d•:uJ~ C<lX'IbiiiiH 'br agl1~ • ; ltla!JH.a.-1 ; •o••:l l{b~ "'q)l~~db ala PMdu~r. 

.:..Mo•g• ~a • ca II.'IO,. • 1u ptea: h~Ua. be~ ~rM!d wt• 1u ru ut on a ad ca • hO,., 1U re t aoab60 .. , ai.U'~ TU ~ <tXI I.'IO{ TIU ~ C<lbl 1.10)a6 . 

. :.. o,. ;,cctllm~ ~. coao: m.aad ' '99?61bu. orb r~p rtaa ~n (') 1a1u ptea:t e~t 

pl!as~ d aa e111 a l b u@!:a c .g)V. 

60 
2-36

(b) Boundary Material: Gypsum Board

FDT : 02.1_Temperature_NV.xls s

CHAPTER 2. PREDICTIIIG HOT GAS LAYER TEMPERA lURE AIID SMOKE 

LAVER HEIGHT Ill A ROOM FIRE WITH IIA lURAL VEIITILATIOII 

COMPARTMEIITWITH THERMALLY THICKITHIII BOUIIDARIES 

Va-sion 19l5D ~ 'bJ)Witg ca• l h1mH4011ab 1U •otg.U tr l,lllpUatm <Ud WI ~ lf l·~ tJ•Ui U Ct i$U Ill . 

P.'ll'\'llfl~'rt In YEllOWCEllS ~tr~ Blter~d 11,• Ul~ UtH. 

P:lrnm~' n In GREEII CEllS 11r~ AUt iflllU~a ll ' $$ $C~d TCffl 1l$ DROP OOWII f,1 f 11U Dr1h$ f,\ltel1al S$ $C~d . 

. O:..II ~q at I1Ht tJ lt $ <II~ cat:ll.~ db ~ p1~<t:~hH<Ud )<ll;~d a lt $ ' I=* CU d Ia 1U llplt 

P,H.'IIII~' IL n a; pl~<t: Ht ~ pi ,~d <IH m bat.to ~ IDI$ It ~ b a WI g~ a1Jyt II a 0:11($). 

~ c•ap' 111tU tiUR~ ' 'o' t1 be 1eadbeDte aa a•al($1$ a; ma:1:. 

Ill PUT PARAMETERS 

COf.1PARTr.1fiiT lllfORMATIOII 

CC411P,'IIIlM 111/VtiQ (!1,) 

411~\.'I IIJM It I.UgQ (I) 

CCtllp.'llllM It H! •.;~•t iM 

W ltV'•H:IU ;,.W:) 

utHetJ•t~ ) 

TCt) 01 VUtfDIIl f bOI (<If) 

11~1·)1 LIU1g n tt;H $$ 0 

Af,1BIEIIT COIIDrTO IIS 

.. :., ... bl! • t :...t n mp~ •atu~ cr,) 

ll~lbl liUUIThPII lll ~ l1h i); pc) 

11~1•" uu•g ThPIIa iCo•d •CUJitf ;J.) 

11~1·)1 ll•l• g~ ~ HMt@ 

1·~1·)1 LIUUI OU$l</ ) 

""'I· 15.00 ' 

10.00 ' 

77.00!,. 

.lllr.' "' 

:111.1:1"' 

.... , ... ,~ ... ll~m 

II ttl~ ... 

to d&llr&d hlll~rlil i11HO 

tl& •&l&c11on 
2-37

FIRES PECIFK:ATIOIIS 

METHOD OF McCAFFREY, QUINTIERE, AND HARKLEROAD(MQH) 

500.00t'"' 91 11at~ 

"-'''*""'"'" ZN'I: X.IOI'II<I<>t olf,.. ~...,,<m,.t"CC,,....,JI :1" btl•ll• llllllle l'>ol" :t.' lll 

., • 6.85 fl /,'. .) ') f'-•••)1 V\' ~ te 11 • T11 - T.,• IJ p~ll.l l9<1> blllpe l.'ltm Ita .. )Q.T~ <fllbl!•t (~ 

a - hatfHMH ra' ~ Ill! ;_t;W) 

A,• ateaOT1JU1JI.10H OpU 119 {II') 

•• • h.;JU !J~ •111.10,_ cpu • 9 ~~) 

co ~CU.I? hat 1JaUYH COHJI::IHt ;_I;WJII _. ~ 

A• • bt.l <l ~<l OT ~ C0111p<tl111~ ·t~ •c t l$119 $I !TaO: bOI •daft$ Ud<ll19 <liM !J •t p~ • . 9$ {II') 

ArU OTW n1111UOO Cp$OIIl}l O'IICUIIIUOO 

.:.,. ;,.w:;, (•.) 

~te .o\,• ateaOT1JU1JI.10H OpU I19 {II') 

w. • vutwtiQ ~~) 

• · ~ •t ~~ ·t ll) 

.:.., - 2.2$ ...... 

llHnnal ~n$b'\'1U n 11m$ OtlculaUon 

1.- (Pcvt) ~ar 

V\ ~ te \> ·U~PII<t pU~1Ja1JH 1211 ~ ¢) 

P •ll~f.)fC0" 1JIC1JH ~Uit/ i);<l,fll ) 

II~ fbi co•, tne1J,. ~atC<l:<.l lt{ t;g-~ 

t; •ll~f.)fC0" 1JIC1),_ QUII<tiCOUIICUJl{ $WAll-~ 

;; • II' lbiCO"tlle1J,_ Q•:t:H $$ \Ill) 

t • 1001.30 $•C 

H$ilt Th'l n t fer CO$ me I$Ot OtiC UIIIUOO 

. , . 1Ji):pCI\ Dlt<t 0 1 i);P) TOft>\, 

V\• ~ te • · · Hat1Jawt:l co~m t •t :V lY ~ 

t pc • •~••"co"tnctb• ~hllalll ~ 1tt1 ;_t;W.tll .. ~ .. ;~c 

Gi ~ lll<tlpiCt=* lt'{ OThl<l~flliiUpO"bt 'bf ~ I~ OT~III pUatl te fh) 

t•thl~ ar.••;~•tb• ($ ¢) 

SH t I=* bW Dll~$ l it 

ArU Of COmpartm$1lt EnCIOtiO}l SUI1\'IC$ BoUIY.Iill1$ t 

A, • (2;,.W,X 1) + 2(. ,X W) + 2(. , X b) - A, 

~ te ,:., , • bt.l <ll~<l OT ~ C0111p<t1111~ ·t~ •c t •$119 $lltl0: bOI •daft$ UC. <III9 ar~a OT !J •t =* • . 9$ {II') 

w. - o:tllpa lllll ~ •twtn• ~~) 

I· • O:tllpa lbll ~ •t h 9U {II) 

. , COIII P,'II111~ •U H;J II) 

A, • ate <I !J~ •U1.11J) • 01=* •119 {II') 

.:.., - ~$ 2 Ill .. 

a:m J:<lt1m$nt Hot Gu LayHnmp$rntl.lr$ W11lllaturnl W n11a Uon 

~~ · 6.85 fl .. /,'. .) ') f'-•••)1 

~~ · ~~ 1.., 

T11 • +T., 
2-38

lr!III!IM 

14 ;; ~ ~ T, 

I 

1-bt ll:ls l.aye' Terrperatu-e 

Nalur3 \krdilalion (MOH Method) 

800 

c:- 700 

t..-600 

~ 500 

1! 400 

GO 300 

~ 200 ~ 100 

0 

0 10 20 30 4) 50 60 

Time lfnin) 
2-39

ESTIMATING SMOKE LAVER HEIGHT 

METHOD OF VAMA. AA DTAI~ AKA 

~o 

11\!Hif 

\I'M) + (Irl )) 

! • Und,f L\,'tl l tl)l t fl) 

0 •lt<ltltlt<IU In Oftlt 111! f.W} 

1 • UU 11'1 I !)1 l tll (ltC) 

I • (JI)IMJ))ItU 1tlt1Ji t .. ) 

A • OOMI)~fl tnKIUIU fill) 

I. • OIOOU1illltg ttl 1)¥1. • 0,0:6/p 

, • IOC9)1 Q,11dtU~ f9'- ) 

, l g l't• .,. , • )01' 

T - IOC9<)1 D..t l ._ptllel l! (.t) 

O.Cll,..tniiiN OkUIIIOn 

A • tw')(l) 

~ A ~fltfDOfM.Jfl) 

W • W.p.l .... ltWI:Ji fl) 

I • OCMp.l .... IU "'JI .. ) 

A. - 2Ut M 

tkltG•• un' Otn•l\' O lcUI:.IOn 

, - ..,. 0 11C: UI310n 110rCOn1 tlnl t<i 

I. - OD:'6ft 

SmoU Gil 1 UJtr Ht l(llltW tl 11 \ll'lU Vtntl;'l110n 

: - (•':!1.0 f .)A, 1 + {Ill ) 

111!1111 Caution! The m::~ke l ayw height I s • oonservati~ esti mote and is only 

intended to pro\tde an lndiclllon W"lere the: hot gas layer is located. Calc:ulcted 

smo Ice I ayer hli ght bll ow the \.9'll height are not credit able si roe the calculati en 

is net aooountlngfor the srnoke exiting the 'M"It. 

nmt "' COmtmtll! ) Smol!t Layer t Smol!t Laytrh$lght 

illl , , iln ) . Io- ~ z (II) !<I\ 

0 1.1& o.ou 3.0$ 10.00 

1 0.76 0. 10 I 1.83 00 

0.72 0.10, 1.83 00 ......,.. o~ 1.83 ~.00 

4 o.u 0. 111 I.U ~.00 

5 U T O.IIS I.U 00 

10 o.u o.m u s 00 

15 o.n 0. 122 u s ~.00 

o.u O. IU I.U ~.00 

'" I.U , .00 

" o.ss O. IU I.U , .00 

" o.ss O.IU us ,,00 

.. us t .IU us .... .. us t .IU us . .. .. t.SS t .Ut us . .. -.:iS ........... u-s . .... t.SS t .IU ,_., ... 

CA UTO II: SMOKE IS EXrTIIIG OUTVEUT 

UTO II: SI,10KE IS EXrTIIIG OUTVEUT 

UTIJ it Sl.tOKE IS EXrTIUG OUTVEUT 

UTIJ it Sl.tOKE IS EXrTIUG OUTVEUT 

UTIJ i t Sl.tOKE IS EXrTIUG OUTVEUT 

UTIJ i t Sl.tOKE IS EXrTIUG OUTVEUT 

UTIJ i t Sl.tOKE IS EXrTIUG OUTVEUT 

UTI:)It Sl.tOKE IS EXrTIUG OUTVEUT 

UTI:)It Sl.tOKE IS EXrTIUG OUTVEUT 

UTI:)U: UAOKE IS EXITIUG OUTVEUT 

UTI:) II: CUOKE IS EXITIUG OUTVEUT 

UTOit $UQt(E IS EXITIItG OUT VEUT 

UTOH: $UQt(E J$ EXITIItG OUTVEUT 

T~tt SUOKE 1$ EXITitG OUTVEIIT 

UTI) tt Ulote E IJ EX ITitG OUT VVIT 

UTI)tt SllotCE IS El lllltG OUTWIT 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

leA 

leA 

leA 

leA 

b 

b 

b 
2-40

Smoke Layer Height 

NaturaiVentilation (Method ofYamana and Tan,. a) 

12 

~ 10 0 

~ 

~ 

8 

E 6 ~ l! 4 

·~ 2 :r 

0 

0 10 20 30 40 

Time(min) 

.. ~ .. WJ~ ca llatDU ar~ baad oa piiiC.)h <IH ~tt ~d . 1U S FP E Haad)Cd; OT Fh 

Pro' C1),_ EagltHIIIg, f" 6:11ba, 1002. 

5) 

c a•:II.1\Du ate b.'IHd oa o:rtn a sHrll pO' u a ad a~~ "hrutlhlltllms. ~ r~H be oTHc• 

ca •laO,. , mayor mar aot a~~ r~a. abl? pr~d•:uJ~ C<lX'IbiiiiH 'br agl1~ • ; ltla!JH.a.-1 ; •o••:l l{b~ "'q)l~~db ala PMdu~r. 

.:..Mo•g• ~a • ca II.'IO,. • 1u ptea: h~Ua. be~ ~rM!d wt• 1u ru ut on a ad ca • hO,., 1U re t aoab60 .. , ai.U'~ TU ~ <tXI I.'IO{ TIU ~ C<lbl 1.10)a6 . 

. :.. o,. ;,cctllm~ ~. coao: m.aad ' '99?61bu. orb r~p rtaa ~n (') 1a1u ptea:t e~t 

pl!as~ d aa e111 a l b u@!:a c .g)V. 

60 
2-41

Example Problem 2-2: Compartment with Natural Ventilation

Example Problem 2.16.1-2

Problem Statement

Con c c csider a compartment that is 12 ft wide x 10 ft long x 8 ft high (w x l x h ) with a simple vent 3 ft

w v v ide x 4 ft tall (w x h ). The construction is essentially 0.5 ft thick gypsum board. The fire is

constant with an HRR of 300 kW. Assume that the top of the vent is 4 ft. Compute the hot gas

temperature in the compartment, as well as the smoke layer height at 2 minutes.

Solution

Purpose:

g

(1) The hot gas layer temperature in the compartment (T ) at t = 2 min after ignition

(2) The smoke layer height (z) at t = 2 min after ignition

Assumptions:

(1) Air properties (ambient) at 77 °F (25 °C)

(2) Simple rectangular geometry (no beam pockets)

(3) One-dimensional heat flow through the compartment boundaries

(4) Constant Heat Release Rate (HRR)

(5) The fire is located at the center of the compartment or away from the walls
2-42

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 02.1_Temperature_NV.xls

Note: Since the gypsum board is greater than 1 inch, it is necessary to use the

correlations for thermally thick material.

FDT Input Parameters: s

c

- Compartment Width (w ) = 12 ft

c

- Compartment Length (l ) = 10 ft

c

- Compartment Height (h ) = 8 ft

v

- Vent Width (w ) = 3 ft

v

- Vent Height (h ) = 4 ft

T

- Top of Vent from Floor (V ) = 4 ft

- Interior Lining Thickness (*) = 6 in

a

- Ambient Air Temperature (T ) = 77 °F

p

- Specific Heat of Air (c )= 1 kJ/kg-K

- Material: Select Gypsum Board on the FDTs

- Fire Heat Release Rate = 300 kW

Results*

Ho gt Gas Layer Temperature (T )

°C (°F)

(Method of MQH)

Smoke Layer Height (z)

 m (ft)

(Method of Yamana and Tanaka)

249 (480) 1.22 (4.00)

T

(smoke exiting vent, z < V )

 *see attached spreadsheet on next page at t = 2 min
2-43

Spreadsheet Calculations

FDT : 02.1_Temperature_NV.xls s

CHAPTER 2. PREDICTIIIG HOT GAS LAYER TEMPERA lURE AIID SMOKE 

LAVER HEIGHT Ill A ROOM FIRE WITH IIA lURAL VEIITILATIOII 

COMPARTMEIITWITH THERMALLY THICKITHIII BOUIIDARIES 

Va-sion 19l5D ~ 'bt)Wiag ca• • h1mu; OIIab 1u •otg.u tr '''~'~PUatm <Ud w• ~ tr ••~ t~•a u cti$U 111 . 

P.'ll'\'llfl~'rt In YEllOWCEllS ~tr~ Blter~d 11,• Ul~ UtH. 

P:lrnm~' n In GREEII CEllS 11r~ AUt iflllU~a ll ' $$ $C~d TCffl 1l$ DROP OOWII f,1 f 11U Dr1h$ f,\ltel1al S$ $C~d . 

. O:..II ~q at I1Ht tJ lt $ <II~ cat:ll.~ db ~ p1~<t:~hH<Ud )<ll;~d a lt $ ' I=* CU d Ia 1U llplt 

P,H.'IIII~' IL n a; pl~<t: Ht ~ pi ,~d <IH m bat.to ~ IDI$ It ~ b a WI g~ a1Jyt II a 0:11($). 

~ c•ap' 111tU tiUR~ ' 'o' t1 be 1eadbeDte aa a•al($1$ a; ma:1:. 

Ill PUT PARAMETERS 

COf.1PARTr.1fiiT lllfORMATIOII 

CC411P,'IIIlM 111/VtiQ (!1,) 

411~\.'I IIJM It I.UgQ (I) 

CCtllp.'llllM It H! •.;~•t iM 

W ltV'•H:IU ;,.W:) 

utHetJ•t~ ) 

TCt) 01 VUtfDIIl f bOI (<If) 

11~1·)1 LIU1g n tt;H $$ 0 

Af,1BIEIIT COIIDrTO IIS 

.. :., ... bl! • t :...t n mp~ •atu~ cr,) 

ll~lbl liUUIThPII lll ~ l1h i); pc) 

11~1•" uu•g ThPIIa iCo•d •CUJitf ;J.) 

11~1·)1 ll•l• g~ ~ HMt@ 

1·~1·)1 LIUUI OU$l</ ) 

""'I· 10.00 ' 

8.00 ' 

77.00!,. 

:lll.l:ln• 

llll' olm 

. ,., "' 

' :l'llm 

ll '!llboln• 

to d&llr&d hlll~rlil i11HO 

tl& •&l&c11on 
2-44

FIRES PECIFK:ATIOIIS 

METHOD OF McCAFFREY, QUINTIERE, AND HARKLEROAD(MQH) 

JOO.OOt'"' 91 11at~ 

"-'''*""'"'" ZN'I: X.IOI'II<I<>t olf,.. ~...,,<m,.t"CC,,....,JI :1" btl•ll• llllllle l'>ol" :t.' lll 

~T., • 6.85 fl /,'. .) ') f'-•••)1 V\' ~ te 11 • T11 - T.,• 11 p~ll.l 19<1> te111pe otm Ita .. )W~ <rllbl!•t (~ 

a - hatfHMH ra' ~ Ill! ;_t;W) 

A,• ateaOT1JU1JI.10H OpU 119 {II') 

•• • h.;JU !J~ •111.10,_ cpu • 9 ~~) 

co ~CU.I? hat 1JaUYH COHJI::IHt ;_I;WJII _. ~ 

A• • bt.l <l ~<l OT ~ C0111p<tl111~ ·t~ •c t l$119 $I !TaO: bOI •daft$ Ud<ll19 <liM !J •t p~ • . 9$ {II') 

ArU OTW n1111UOO Cp$OIIl}l O'IICUIIIUOO 

.:.,. ;,.w:;, (•.) 

~te .o\,• ateaOT1JU1JI.10H OpU I19 {II') 

w. • vutwtiQ ~~) 

• · ~ •t ~~ ·t ll) 

.:.., - 1.11111 .. 

llHnnal ~n$b'\'1U n 11m$ OtlculaUon 

1.- (Pcvt) ~ar 

V\ ~ te \> ·U~PII<t pU~1Ja1JH 1211 ~ ¢) 

P •ll~f.)fC0" 1JIC1JH ~Uit/ i);<l,fll ) 

II~ fbi co•, tne1J,. ~atC<l:<.l lt{ t;g-~ 

t; •ll~f.)fC0" 1JIC1),_ QUII<tiCOUIICUJl{ $WAll-~ 

;; • II' lbiCO"tlle1J,_ Q•:t:H $$ \Ill) 

t • 3~0U l4 ,.c H$ilt Th'l n t fer CO$ me I$Ot OtiC UIIIUOO 

. , . 1Ji):pCI\ Dlt<t 0 1 i);P) TOft>\, 

V\• ~ te • · · Hat1Jawt:l co~m t •t lY ~ 

t pc • •~••"co"tnctb• ~hllalll ~ 1tt1 ;_t;W.tll .. ~ .. ;~ c 

Gi ~ lll<tlpiCt=* lt'{OThl<l,flliiUpO"bt 'bf ~ I~ OT'IIIpUatl te fh) 

t•thl~ ar.••;~•tb• ($ ¢) 

SH t I=* bW Dll~$ l it 

ArU Of COmpartm$1lt EnCIOtiO}l SUI1\'IC$ BoUIY.Iill1$ t 

A, • (2;,.W,X 1) + 2(. ,X W) + 2(. , X b) - A, 

~ te ,:., , • bt.l <ll~<l OT ~ C0111p<t1111~ ·t~ •c t •$119 $lltl0: bOI •daft$ U C. <III9 ar~a OT !J •t =* • . 9$ {II') 

w. - o:tllpa lllll ~ •twtn• ~~) 

I· • O:tllpa lbll ~ •t h 9U {II) 

. , COIII P,'II111~ •U H;J II) 

A, • ate <I !J~ •U1.11J) • 01=* •119 {II') 

.:.., - $$.$$Ill .. 

a:m plr1m$nt Hot Gu LayHnmp$rntl.lr$ W11lllaturnl W n11aUon 

~~ · 6.85 fl .. /,'. .) ') f'-•••)1 

~~ · ~~ 1.., 

T11 • +T., 
2-45

lr!III!IM 

11m~ After 1 ll1on t h, 

~ ..... ) ~ C. ~WA0 14 

' (+.!)(! - 1 " 0.05 

' "' 0.04 

' "' 0.0$ 

' "' 0.0$ 

' "' 0.02 

" "' 0.02 

" "' 0.01 

" 12(1(1 0.01 

" 15(1(1 0.01 

" 1$(1(1 0.01 

" 2 1(1(1 0.01 

" 24(1(1 0.01 

" 27(1(1 0.01 

" $(1(1(1 0.01 

55 $$(1(1 0.01 

" $~(1(1 0.01 

... 

!10 

T, 

.i - ~$.(1(1 

uu~ ~~ 

224. 14 522. 1J 

2$3.$1 $$7.$ 1 

25 1.5~ 543 5~ 

2H 12 55~ 12 

~$. 10 SHIO 

$ 1$.$~ ~11.5~ 

$2$.~~ U~ 

UI.Jii u~ .J~ 

$$1.3~ ~43 ~~ 

$HI~ ~5~ .• ~ 

$~ S ~~7 .2$ 

$7UO J.~(I 

$$$.2$ ~$1.2$ 

$$~.J 1 ~$7 .J 1 

$~$. 10 U$. 10 

1-bt ll:ls l.aye' Terrpe131:u-e 

Nalur3 \krdilalion (MOH Method) 

T, T, 

"" rF> 

25.(1(1 (7.(1(1 

22J.~~ .UU4 

~.14 JSU5 

~U1 sou~ 

27U~ M~ 

2SU2 547.02 

$1$.1(1 ~(IJ.$$ 

$$$.$~ uu~ 

$5$.3~ ~~~.1 ~ 

$~~ . .IIi ~~ I.U U~ 10.5~ 

$$U~ 727.0$ 

$~4.2$ 74 1.7 1 

JOUO 54.$~ 

J(l$.2$ ~o 

JI4.J1 777.U 420.1(1 ?'$$.1$ 

900 1,_.,_. ______ ,_ ______________________________________ ., 

c:- 800 

t.,.. 700 

e 600 :1 500 

~ 400 

g- 300 

o!' 200 

100 

0 

0 10 20 30 

Time lfnin) 

4) 50 60 
2-46

ESTIMATING SMOKE LAVER HEIGHT 

METHOD OF VAMA. AA DTAI~ AKA 

~o 

11\!Hif 

\I'M) + (Irl )) 

! • Und,f L\,'tl l tl)l t fl) 

0 •lt<ltltlt<IU In Oftlt 111! f.W} 

1 • UU 11'1 I !)1 l tll (ltC) 

I • (JI)IMJ))ItU 1tlt1Ji t .. ) 

A • OOMI)~fl tnKIUIU fill) 

I. • OIOOU1illltg ttl 1)¥1. • 0,0:6/p 

, • IOC9)1 Q,11dtU~ f9'- ) 

, l g l't• .,. , • )01' 

T - IOC9<)1 D..t l ._ptllel l! (.t) 

O.Cll,..tniiiN OkUIIIOn 

A • tw')(l) 

~ A ~fltfDOfM.Jfl) 

W • W.p.l .... ltWI:Ji fl) 

I • OCMp.l .... IU "'JI .. ) 

A, - II, ISM 

tkltG•• un' Otn•l\' O lcUI:.IOn 

, - ..,. 0 11C: UI310n 110rCOn1 tlnl t<i 

I. - OD:'6ft 

SmoU Gil 1 UJtr Ht l(llltW tl 11 \ll'lU Vtntl;'l110n 

: - (•':!1.0 flA. 1 + {Ill ) 

111!1111 Caution! The m::~ke l ayw height I s • oonservati~ esti mote and is only 

intended to pro\tde an lndiclllon W"lere the: hot gas layer is located. Calc:ulcted 

smo Ice I ayer hli ght bll ow the \.9'll height are not credit able si roe the calculati en 

is net aooountlngfor the srnoke exiting the 'M"It. 

nmt "' COnatmtll! ) Smol!t Layer t Smol!t Laytrh$lght 

illl , , iln ) . Io- ~ z (II) !<I\ 

0 1.1& o.ou '·"' $.0(1 

1 0.7 1 0. 107 1.22 .,, o.u 0. 112 1.22 .,, --.-.. Om 1.22 .,, 4 o.u 0.111 1.22 .,, 5 o.u 0. 120 1.22 ... 10 uo 0. 121 1.22 ... 15 o.sa O. IS2 1.22 ... o.sc O. IU 1.22 ... "' 1.22 .,, 

" o.s .. 0. 140 1.22 .,, 

" 0." O.l.al 1.22 .,, .. t.U t .IU 1.22 uo .. t.n t .14S 1.2:2 . .. .. t.n t .I.U 1.2:2 . .. --.:<0 --.-.-.. I.U ... .. Ul t .IU I.U <N 

CA UTO II: SI.IOKE IS EXrTIIIG OUTVEIIT 

UTO II: SI,10KE IS EXrTIIIG OUTVEIIT 

UTIJ it Sl.tOKE IS EXrTIIIG OUTVEIIT 

UTIJ U: Sl.tOKE IS EXrTIIIG OUTVEIIT 

UTIJ it Sl.tOKE IS EXrTIUG OUTVEIIT 

UTIJ i t Sl.tOKE IS EXrTIUG OUTVEIIT 

UTIJ U: Sl.tOKE IS EXrTIUG OUTVEUT 

UTI:)It Sl.tOKE IS EXrTIUG OUTVEUT 

UTI:)It Sl.tOKE IS EXrTIUG OUTVEUT 

UTI:)U: UAOKE IS EXITIUG OUTVEUT 

UTI:) II: Ct.IOKE IS EXITIUG OUTVEUT 

UTOit $UQt(E IS EXITIItG OUT VEUT 

UTOH: $UQt(E 1$ EXITIItG OUTVEUT 

T~tt SUOKE 1$ EXITIIG OUTVEitT 

un ) tt Ulote E tJ EX ITitG OUT VVtT 

UTI)tt SllotCE IS El lllltG OUTWIT 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

leA 

leA 

leA 

leA 

b 

b 

b 
2-47

Smoke Layer Height 

NaturaiVentilation(Method ofYamana and Tan,.a) 

g 

gs 

57 

~6 

e5 

~4 

"3 

·~2 

:1: 1 

0 

0 10 20 3J 40 50 

Time(min) 

mw ~ .. )W~ ca •l1tbU ar~ baad o• pll I! tJ~tt ~d . 1U SFP E HaHI>oc+; 01 Fh 

Pro'C1)" E•gi& HIIIg, 3"" 6:1lb•. 2002. 

a• •l1tbu ate b.'IHd o• o:m• asHrl'lp1)) U a•d <V~ ••• u~ •tlhlltiO . ~ r~H be Of He• ca •l'IO " ma-vor mar •ot <V~ r~a. abl! pr~d•:U ~ C<lX'IbiiiiH 'br agl1~ • $1b<IOH.a•d ' 'o••:l \'b~ lt,qm~db t lt 'bnMdu~r. 

,:.,Mo•g• ~a • ca •l'IO,_ 111U pte<t: h~Ua> b~~ . ~IM!d WU 1U IH Ut ona .. l ca · hO,., 1u r~ t •oal:c;o"' ara •' ~ TU ~ ax • raor ra~ ~ cat:• 1.10' " · 

:.. o,. ,,cctl'lh'l~ tc. co•o: m.a .. l ' '99?' 1bu. orb r~p rtat ~n (') r. ~ ' Pte a:a; ~~ t 

pl!aH ~"I at r11 b u@!:• c .g,v. 

60 
2-48

Example Problem 2-3: Compartment with Natural Ventilation

Example Problem 2.16.1-3

Problem Statement

Consider c c c a compartment that is 8 ft wide x 8 ft long x 6 ft high (w x l x h ) with a simple vent that

v v is 2 ft wide x 3 ft tall (w x h ). The construction is essentially 0.75 ft thick concrete. The fire is

constant with an HRR of 1,000 kW. Assume that the top of the vent is 3 ft. Compute the hot gas

temperature in the compartment, as well as the smoke layer height at 3 minutes.

Solution

Purpose:

g

(1) Determine the hot gas layer temperature in the compartment (T ) at t = 3 min after

ignition

(2) Determine the smoke layer height (z) at t = 3 min after ignition

Assumptions:

(1) Air properties (ambient) at 77 °F (25 °C)

(2) Simple rectangular geometry (no beam pockets)

(3) One-dimensional heat flow through the compartment boundaries

(4) Constant Heat Release Rate (HRR)

(5) The fire is located at the center of the compartment or away from the walls

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 02.1_Temperature_NV.xls

Note: Since concrete thickness is greater than 1 inch, it is necessary to use the

correlations for thermally thick material.
2-49

FDT Input Parameters: s

c

- Compartment Width (w ) = 8 ft

c

- Compartment Length (l ) = 8 ft

c

- Compartment Height (h ) = 6 ft

v

- Vent Width (w ) = 2 ft

v

- Vent Height (h ) = 3 ft

T

- Top of Vent from Floor (V ) = 3 ft

- Interior Lining Thickness (*) = 9 in

a

- Ambient Air Temperature (T ) = 77 °F

p

- Specific Heat of Air (c )= 1 kJ/kg-K

- Material: Select Concrete on the FDTs

- Fire Heat Release Rate = 1,000 kW

Results*:

Ho gt Gas Layer Temperature (T )

°C (°F)

(Method of MQH)

Smoke Layer Height (z)

 m (ft)

(Method of Yamana and Tanaka)

571 (1,060) 0.91 (3.00)

compartment filled with smoke)

 *see spreadsheet on next page at t = 3 min
2-50

Spreadsheet Calculations

FDT : 02.1_Temperature_NV.xls s

CHAPTER 2. PREDICTIIIG HOT GAS LAYER TEMPERA lURE AIID SMOKE 

LAVER HEIGHT Ill A ROOM FIRE WITH IIA lURAL VEIITILATIOII 

COMPARTMEIITWITH THERMALLY THICKITHIII BOUIIDARIES 

Va-sion 19l5D ~ 'bJ)Witg ca• l h1mH4011ab 1U •otg.U tr l,lllpUatm <Ud WI ~ lf l·~ tJ•Ui U Ct i$U Ill . 

P.'ll'\'llfl~'rt In YEllOWCEllS ~tr~ Blter~d 11,• Ul~ UtH. 

P:lrnm~' n In GREEII CEllS 11r~ AUt iflllU~a ll ' $$ $C~d TCffl 1l$ DROP OOWII f,1 f 11U Dr1h$ f,\ltel1al S$ $C~d . 

. O:..II ~q at I1Ht tJ lt $ <II~ cat:ll.~ db ~ p1~<t:~hH<Ud )<ll;~d a lt $ ' I=* CU d Ia 1U llplt 

P,H.'IIII~' IL n a; pl~<t: Ht ~ pi ,~d <IH m bat.to ~ IDI$ It ~ b a WI g~ a1Jyt II a 0:11($). 

~ c•ap' 111tU tiUR~ ' 'o' t1 be 1eadbeDte aa a•al($1$ a; ma:1:. 

Ill PUT PARAMETERS 

COf.1PARTr.1fiiT lllfORMATIOII 

CC411P,'IIIlM 111/VtiQ (!1,) 

411~\.'I IIJM It I.UgQ (I) 

CCtllp.'llllM It H! •.;~•t iM 

W ltV'•H:IU ;,.W:) 

utHetJ•t~ ) 

TCt) 01 VUtfDIIl f bOI (<If) 

11~1·)1 LIU1g n tt;H $$ 0 

Af,1BIEIIT COIIDrTO IIS 

;:.111 bl! 1 t :...t n mpe ratue (r,) 

ll~lbl liiii\IThPII lll ~ l1h i); pc) 

11~1·)1 lllllg ThPIIa iCOid iCUJit{ ;J.) 

11~1·)1 lllll g~ ~ HMt@ 

11~1·)1 LIIIUI OU$l</ ) 

77.00!,. 

llii'Om 

011 '-ln• 

llll'.lm 

II:Ultln• 

to d&llr&d PHI~flil i11HO 

tl& •&l&c11on 
2-51

FIRES PECIFK:ATIOIIS 

METHOD OF McCAFFREY, QUINTIERE, AND HARKLEROAD(MQH) 

IOOO.OOt'"' 

91 "at~ 

"-'''*""'"'" ZN'I: X.IOI'II<I<>t olf,.. ~...,,<m,.t"CC,,....,JI :1" btl•ll• llllllle l'>ol" :t.' lll 

~T., • 6.85 fl /,'. .) ') f'-•••)1 V\' ~ te 11 • T11 - T.,• 11 p~ll.l 19<1> te111pe otm Ita .. )W~ <rllbl!•t (~ 

a - hatfHMH ra' ~ Ill! ;_t;W) 

A,• ateaOT1JU1JI.10H OpU 119 {II') 

•• • h.;JU !J~ •111.10,_ cpu • 9 ~~) 

co ~CU.I? hat 1JaUYH COHJI::IHt ;_I;WJII _. ~ 

A• • bt.l <l ~<l OT ~ C0111p<tl111~ ·t~ •c t l$119 $I !TaO: bOI •daft$ Ud<ll19 <liM !J •t p~ • . 9$ {II') 

ArU OTW n1111UOO Cp$OIIl}l O'IICUIIIUOO 

.:.,. ;,.w:;, (•.) 

~te .o\,• ateaOT1JU1JI.10H OpU I19 {II') 

w. • vutwtiQ ~~) 

• · ~ •t ~~ ·t ll) 

A, • O.$S ...... 

llHnnal ~n$b'\'1U n 11m$ OtlculaUon 

1.- (Pcvt) ~ar 

V\ ~ te \> ·U~PII<t pU~1Ja1JH 1211 ~ ¢) 

P •ll~f.)fC0" 1JIC1JH ~Uit/ i);<l,fll ) 

II~ fbi co•, tne1J,. ~atC<l:<.l lt{ t;g-~ 

t; •ll~f.)fC0" 1JIC1),_ QUII<tiCOUIICUJl{ $WAll-~ 

;; • II' lbiCO"tlle1J,_ Q•:t:H $$ \Ill) 

t . 1:1~31 .$$ ,.c H$ilt Th'l n t fer CO$ me I$Ot OtiC UIIIUOO 

. , . 1Ji):pCI\ Dlt<t 0 1 i);P) TOft>\, 

V\• ~ te • · · Hat1Jawt:l co~m t •t lY ~ 

t pc • •~••"co"tnctb• ~hllalll ~ 1tt1 ;_t;W.tll .. ~ .. ;~ c 

Gi ~ lll<tlpiCt=* lt'{OThl<l,flliiUpO"bt 'bf ~ I~ OT'IIIpUatl te fh) 

t•thl~ ar.••;~•tb• ($ ¢) 

SH t I=* bW Dll~$ l it 

ArU Of COmpartm$1lt EnCIOtiO}l SUI1\'IC$ BoUIY.Iill1$ t 

A, • (2;,.W,X 1) + 2(. ,X W) + 2(. , X b) - A, 

~ te ,:., , • bt.l <ll~<l OT ~ C0111p<t1111~ ·t~ •c t •$119 $lltl0: bOI •daft$ U C. <III9 ar~a OT !J •t =* • . 9$ {II') 

w. - o:tllpa lllll ~ •twtn• ~~) 

I· • O:tllpa lbll ~ •t h 9U {II) 

. , COIII P,'II111~ •U H;J II) 

A, • ate <I !J~ •U1.11J) • 01=* •119 {II') 

.:.., - 23.17 111 .. 

a:m plr1m$nt Hot Gu LayHnmp$rntl.lr$ W11lllaturnl W n11aUon 

~~ · 6.85 fl .. /,'. .) ') f'-•••)1 

~~ · ~~ 1.., 

T11 • +T., 
2-52

iilillii 

11m~ After 1 ll1on t h, 4T, T, T, T, 

~ ....... .... ili\t\l,tll .. - 1<) ,. '"' "" t'Fl 

' (+.!)(+ - - ~$.(1(1 25.00 77.00 

I " 0.22 4 54.?'2 752.72 4(3.72 335.50 

' '" O.IS 5 10.41 303.4 1 $$5.41 ~35.7 4 

' "' 0.1$ 5Jii.03 U4.03 571.03 1053.37 

• ,., 0. 11 HUI 370.31 537.31 1108.25 

' '" O.IIJ 534.U 33U2 2 114l.$2 

" "' (U)7 ~~7.44 3S5.44 ~32 .44 1278.33 

" "' (U)~ 7 14,10 1012. 10 7$$.1!) 1$~2.$$ 

" 1200 (U)$ 7 4!1. 1$ 1047. 13 774.1$ 1425.52 

" 1500 (U) 4 777.5~ 107S.H $1)2.$~ 147U 2 

" 1$(11) 0.(!4 $(! 1.5~ 10$U~ U~ ISIUO 

" 2 100 o.u 322.42 1120.42 Ul .42 IS SU S 

" '"' (U)$ UU2 11$U2 3~U2 S$U~ 

"' 2700 (U)$ 357.5$ 1155.5$ a$2.$$ IS2U 7 

" $(!(!(+ 0.0$ 372.7$ 1170.73 3$7.7$ IS.t$.!)2 

" \f~!JIJ IU'~ n~ .; I IU,f l> ~ l l.fl> ... If 

" $~(!(! (U)$ 3$U2 11$7.72 $24.72 ~$ $ 

1-bt ll:ls l.aye' Terrperatu-e 

Naura \kntil31ion (MOH Method) 

2000 

E15oo 

~ 

~ 

• ~ 

1000 

500 

- ~ 

0 

0 10 20 30 40 50 60 

Time (rrin) 
2-53

ESTIMATING SMOKE LAVER HEIGHT 

METHOD OF VAMA. AA DTAI~ AKA 

~o 

11\!Hif 

\I'M) + (Irl )) 

! • Und,f L\,'tl l tl)l t fl) 

0 •lt<ltltlt<IU In Oftlt 111! f.W} 

1 • UU 11'1 I !)1 l tll (ltC) 

I • (JI)IMJ))ItU 1tlt1Ji t .. ) 

A • OOMI)~fl tnKIUIU fill) 

I. • OIOOU1illltg ttl 1)¥1. • 0,0:6/p 

, • IOC9)1 Q,11dtU~ f9'-) 

, l g l't• .,. , • )01' 

T - IOC9<)1 D..t l ._ptllel l! (.t) 

O.Cll,..tniiiN OkUIIIOn 

A • tw')(l) 

~ A ~fltfDOfM.Jfl) 

W • W.p.l .... ltWI:Ji fl) 

I • OCMp.l .... IU "'JI .. ) 

A, - us. 

tkltG•• un' Otn•l\' O lcUI:.IOn 

, - ..,. 0 11C: UI310n 110rCOn1 tlnl t<i 

I. - OD:'6ft 

SmoU Gil 1 UJtr Ht l(llltW tl 11 \ll'lU Vtntl;'l110n 

: - (•':!1.0 f .)A, 1 + {Ill ) 

111!1111 Caution! The m::~ke l ayw height I s • oonservati~ esti mote and is only 

intended to pro\tde an lndiclllon W"lere the: hot gas layer is located. Calc:ulcted 

smo Ice I ayer hli ght bll ow the \.9'll height are not credit able si roe the calculati en 

is net aooountlngfor the srnoke exiting the 'M"It. 

nmt "' COmtmtll! ) Smol!t Layer t Smol!t Laytrh$lght 

illl , , iln ) . Io- ~ z (II) !<I\ 

0 1.1& o.ou u s eo 

1 ..... O. IU 0.~ I 3.00 

.... 0. 174 0.~ I $.00 ......., O tu 0.~ I 3.00 

4 0.41 O. IU 0.~ I $.0(1 

5 .... O. IU I).) I $.00 

10 O.S? 0.201 !).) I $.00 

15 o.u 0.'211 !).) I $.00 

0.)4 0.'225 !).) I 3.00 

' ' 0.!1 $.00 

" o.n O.:H 1.31 $.00 

" o.n U 41 U l $.00 

.. ..,, U:.U Ul .... .. Ul 1.14) Ul . ..... . ...un Ul 

--.:it ..... ..,, "' .. t .U t .UI ._,. "' " 

CA UTO II: SMOKE IS EXrTIIIG OUTVEIIT 

UTO II: SI,10KE IS EXrTIIIG OUTVEIIT 

UTIJ it Sl.tOKE IS EXrTIIIG OUTVEIIT 

UTIJ U: Sl.tOKE IS EXrTIIIG OUTVEIIT 

UTIJ it Sl.tOKE IS EXrTIUG OUTVEIIT 

UTIJ it Sl.tOKE IS EXrTIUG OUTVEIIT 

UTIJ it Sl.tOKE IS EXrTIUG OUTVEUT 

UTI:)It Sl.tOKE IS EXrTIUG OUTVEUT 

UTI:)Jt Sl.tOKE IS EXrTIUG OUTVEUT 

UTI:)U: UAOKE IS EXITIUG OUTVEUT 

UTI:)Jt Ct.IOKE IS EXITIUG OUTVEUT 

UTOit Ct.IOKE IS EXITIItG OUT VEIIT 

UTOH: SUOKE 1$ EXITIItG OUTVEIIT 

T~tt SUOKE 1$ EXITI.O OUTVEitT 

un ) tt Ulote E tJ EX ITI.O OUT VVtT 

UTI)tt SllotCE IS EI RlltG OUTWIT 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

leA 

leA 

leA 

leA 

b 

b 

b 
2-54

Smoke Layer Height 

NaturaiVentilation (Method ofYamana and Tan,. a) 

7 

g6 

~5 

'E4 

~3 

2!2 ·" ~ 1 

0 

0 10 20 3J 40 50 

Time(min) 

.. ~ .. WJ~ ca llatDU ar~ baad oa piiiC.)h <IH ~tt ~d . 1U S FP E Haad)Cd; OT Fh 

Pro' C1),_ EagltHIIIg, f" 6:11ba, 1002. 

c a•: II.1\Du ate b.'IHd oa o:rtn a sHrll pO' u a ad a~~ "hrutlhlltllms. ~ r~H be oTHc• 

ca •laO,. , mayor mar aot a~~ r~a. abl? pr~d•:uJ~ C<lX'IbiiiiH 'br agl1~ • ; ltla!JH.a.-1 ; •o••:l 

l{b~ "'q)l~~db ala PMdu~r. 

,oi.,IQOig• ~a • ca II.'IO,_ • 1U pte<t: h~Ua> be~ a ~IM!d wt• IU !H Ut OUa ad ca l hO,., 

1U re t aoab60 .. , ai.U'~ TU ~ <tXI I.'IO{ TIU ~ C<lbl 1.10)a6 . 

. :.. o,. ;,cctllm~ ~. coao: m.aad ' ' 99?61bu. orb r~p rtaa ~n (') 1a1u ptea:t e~t 

pl!as~ d aa e111 a l b u@!:a c .g)V. 

eo 
2-55

Example Problem 2-4: Compartment with Forced Ventilation

2.16.2 Forced Ventilation

Example Problem 2.16.2-1

Problem Statement

Consider c c c a compartment that is 16 ft wide x 16 ft long x 12 ft high (w x l x h ), with a vent opening

v v that is 3 ft wide x 7 ft tall (w x h ). The forced ventilation rate is 1,000 cfm (exhaust). Calculate the

hot gas layer temperature for a fire size of 500 kW at 2 minutes after ignition. The compartment

boundaries are made of (a) 1 ft thick concrete and (b) 0.7 inch thick gypsum board.

Solution

Purpose:

For two different interior lining materials determine the hot gas layer temperature in the

g

compartment (T ) at t = 2 min after ignition.

Assumptions:

(1) Air properties (ambient) at 77 °F (25 °C)

(2) Simple rectangular geometry (no beam pockets)

(3) One-dimensional heat flow through the compartment boundaries

(4) Constant Heat Release Rate (HRR)

(5) The fire is located at the center of the compartment or away from the walls

(6) The bottom of the vent is at the floor level

(7) The compartment is open to the outside at the inlet (pressure = 1 atm)
2-56

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) For Concrete:

02.2_Temperature_FV.xls

(b) For Gypsum Board:

02.2_Temperature_FV.xls

Note: Since concrete thickness is greater than one inch, it is necessary to use the

correlations for thermally thick material. However, since gypsum board thickness is less

than 1 inch, it is necessary to use correlations for thermally thin material. Also, each

g

spreadsheet has a different method to calculate the hot gas layer temperature (T ).

We are going to use both methods to compare the results.

FDT Input Parameters: (for both spreadsheets) s

c

- Compartment Width (w ) = 16 ft

c

- Compartment Length (l ) = 16 ft

c

- Compartment Height (h ) = 12 ft

- Interior Lining Thickness (*) = 12 in (concrete) and .7in (gypsum board)

a

- Ambient Air Temperature (T ) = 77 °F

p

- Specific Heat of Air (c )= 1 kJ/kg-K

- Material: Select Concrete and Gypsum Board on the respective FDTs

- Compartment Mass Ventilation Rate (m) = 1,000 cfm

- Fire Heat Release Rate = 500 kW

- Time after ignition (t) = 2 min.

Results*

Boundary Material Ho g

t Layer Gas Temperature (T )

°C (°F)

Method of Foote, Pagni

& Alvares (FPA)

Method of Deal

& Beyler

Concrete 142 (288) 87 (190)

Gypsum Board 218 (426) 223 (452)

 *see spreadsheets on next page at t = 2 min.
2-57

Spreadsheet Calculations

(a) Boundary Material: Concrete

FDT : 02.2_Temperature_FV.xls s

CHAPTER 2. PREDICTING HOT GAS LAYER TEMPERATURE IN A ROOM 

FIRE WITH FORCED VENTILATION 

COMPARTMENT WITH THERMALLY THICK!THIN BOUNDARIES 

Version 1805.0 

The following calcol31ions estimate the hot gas layertemper.rure and smolollayer height in enclosure ire. 

Parameters in YELLOW CELLS are Entered by the User. 

Parameters in GREEN CELLS are ALiomatically Selected from the DROP DOWN M ENUforthe Material Selected . 

.All subsequent output wlues are calculated bythe spreadsheet and based on wlues specified in the input 

parameters. This spreadsheet is protected and secure w avoid errors due to a wrong entry in a cell(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

COMPARTMENT INFORMATION 

Compartment VlAdth (w ) 

Compartment Length 0.) 

Compartment Height (h.) 

Interior Uning Thickness (6) 

AMBIENT CONDITIONS 

.Anb ient Ptr Temper abJ re (T,,) 

Speci1ic Heat of Air (c11) 

.Anb ient Pir Density ( P,) 

THERMAL PROPERTIES 0 F COM PA RTM E NT ENCLOSING SURFACES 

16DO 1t 

16DO 1t 

12DO 1t 

nool·• 

f------:1,.,0~0 ""% 

1.18 "9111 

Interior UninQ Thermal Inertia (kpc) 2.9 \t iV fll c 

Interior Uning Thermal ConductiWy(k) 0.0016 •:I.N.t!1 4< 

Interior Uning Specific Heat(c) 0.75 t:J.tg-K 

Interior Uning Oensity(p) 2400 t<llll 

Note: ~r density will autom<nic:a lly correct w ilh .Anbient ~r Temperature (T ,,) Input 

, .... , .... 3.60 IJI 

25.00 ~ 

2re.OO K 
2-58

COMPARTMENT MASS VENTILATION FLOW RATE 

Forced Ventilation Flow Ral»l (m) 

FIRE SPECIFICATIONS 

1 000 DO lcn11 

Fire Heat Release Rate (Q) &IODO •:V\

1 

I Calculate I 

METHOD OF FOOTE, PAGNI, AND ALVARES (FPA) 

RH!I< •o: : s,:p E ,"'f<UidOO$. <:'! i:~ P :o 1?UUfl l,:~ ,•,:g J"" Edltb •, 2002, P ag; J-177 . 

Where lL ToJ = T oJ. T ~= upper layer gas temperature rise above ambient (K) 

T~= ambient air temperature (K) 

Q = heat releaser ate ofthe fire (kW) 

m = compartment mass ventilation flow rate (k9"sec) 

a.= specific heat of air (kJA<g·K) 

t.. = convective heat transfer coefficient (kW/m2-K) 

A:r= total area of the compartment enclosing surface boundaries (m') 

Thermal PEnetration Time Calculation 

~ = (PcoJI<)(orz/ 

Where t = thermal penetration time (sec) 

p =interior construction density (kg/m ~ 

C\> = interior construction heat capaci~ (kJA<g-l-9 

k =interior construction thermal conductivity(kW/m-1-9 

0 = in~rior construction thickness (m) 

t,. = 26128.93 sec 

Hect Trcnsfer Coefficient Calculation 

1\: = v(kPclt) for t < t,. or (k/0) fort> t 

Where t.. = heattr ansfer coefficient(kW/mz·l-9 

kpc = in~rior construction thermal inertia (kW/mz-K)z·s ec 

(a thermal property tA material rc5pon5iblc tor the rate ottcmpcratl.uc ri5 c) 

t= time after ignition (sec) 

See table below for results 

Area of Co mp~ ment En dosing Surface Boundc.-ies 

kr= 2(wcx l:) +2 (hcxw.:) +2 (hex I:) 

Where Ar= total area of the compartment enclosing surface boundaries (ml 

w.: = compartment width (m) 

l: = compartment length (m) 

h.:= compartment height (m) 

A;= area of ventilation opening (ml 

Ar= 118.92 m.: 

Compartment Hot Gas layer Temperature With Force:! Ventilction 

lLToJIT~ = 0.63(0/ma. o{'z(tt kr/ma.)~ . .,~ 

lLToJ = ToJ· T~ 

ToJ = lLToJ+ T~ 

o .n2 111 A: c 

OSS9 tc C 
2-59

· lo l~ion It I AT0/T o 

I min) lsec) 

h,, ~~ ~~ ~~~) ~~~) 0 

1 

3 

4 

5 

10 

15 

40 

50 

55 

60 

" .22 

"' ).13 

"' ).11 

"' ).10 

"' )7 

"' .06 

"" 

'"' "" '"' .03 

"" )3 

"" .03 

"" .03 

0.35 103.76 

0.42 126.45 

0.45 133.17 

0.47 138.63 

ifr 157.05 

168.94 

0.68 201.57 

0.70 209.83 

0.72 213.46 

0.73 216.83 

Hot Gas l ayer Ten1)el'ature 

Forced Ventilation- FPA Method 

29800 25.00 77.00 

401.76 :::* 263.77 

424A5 304.61 

431.17 158.17 316.71 

43663 16363 326.54 

45505 18205 359.70 

466.94 193.94 381.10 

391 :----

421. :----

431. 

499.57 226.57 439.82 

507.83 234.83 454.69 

511A6 238A6 461.22 

514.83 241.83 467.29 

L:' 

t.., 

400 500 ;;::~~~ 

~300 (" ------------------------------------------~ 

1200 ----------------------------------------------~ E 

~100 !-------------------------------------------------1 

0 L-----------------------------------------~ 0 10 20 30 40 50 60 

Time (min) 
2-60

METHOD OF DEAL AND BEYLER P,~ 'I: I? •o:: s,: PE "i.ltidt\i~ .:<" ~ .::rv:t Er.g l,:;;o,.,-{,:g, J''" E<lltb•. 2002, Pag: J-178. 

Hect Trcnsfer Coefficient Calculation 

tt: = 0.4v(kpc/tl fort< flo 

Where 

"· = 

t.. = heattr ansfer coefficient(kW/mz· 1-9 

kpc = in~rior construction thermal inertia (kW/mz-K)z·s ec 

(a thermal property of material responsible for the rate oftemperature rise) 

0 =thickness of interior lining (m) 

0.088 kW/m--K 

Area of Co mpcrt ment En dosing Surface Bound~ies 

Ar= 2(w eX l:) + 2(h eX IA0 + 2(hcX l:) 

Ar= 118.92 m.: 

Compartment Hot Gas layer Temperature With Force:! Ventilction 

Where lL ToJ = T oJ • T ~=upper layer gas temperature rise above ambient (K) 

T~= ambient air temperature (K) 

Q = heat releaser ate ofthe fire (kW) 

m = compartment mass ventilation flow rate (k9"sec) 

C\> =specific heat of air (kJ/Kg-J.9 

1\: = convective heat transfer coefficient (kW/mz·K) 

Ar= total area of the compartment enclosing surface boundaries (m') 

·;me After lon~ion (I l 

(min) (sec) 

0 . 2ss.oo 25.00 n.oo 

1 ~ .09 45.39 343.39 70.39 158.70 

2 120 .06 62.87 3~.87 87.87 190.16 

4 240 .04 86.39 384.39 11139 232.50 

5 :DO .04 95.50 393.fll 120.50 248.90 

~-~1o __ +--~~o~o~--~.o~,3~-+~1~~l .. ~~-+-~4n7~ .. ~~~-~1541.3~3--~~ 15 930 ,. 153.41 451.41 178A 1 353.15 

20 1200 )2 172.57 470.57 197.57 387 62 

2400 225. 523. 

~ 236. 534. 2S1 
2-61

600 

~ 

500 

t400 

, 

e 

~ 300 

• 

~ 200 

,'!! f 

100 

0 

0 

Summarvof ResUt 

600 

500 

E 40o 

e 

a 300 

i 200 ~ 

100 

0 

IJUIIM 

0 

/ 

Hd Gas layer Temperature 

Forced \krrtilation · Deal and Be~erMethod 

--

10 20 

10 

30 40 

Time (min) 

Hd Gas layer Temperature 

F' orced Ventilation 

20 30 

Time (min) 

50 

40 50 

The above calcolalionsare based on pinciples de'Wioped in1he SF'PE Haldbookof Fire A-otection 

&IQineerinQ, 3"' Ei::lition, 2002. 

C-'cutftims are based on certan assurrptDns ard have irherentlimitJ!ions. The results of such 

cabulaims may or may rm ha'W reasonaHe p-edictiw capabihies for a gi'Wn situaim, and should 

onlybe interp~d byal ilfonned user. 

Plthough each calcdalion in the spreadsheEt has been wi1ied with the results ofhand c-'cdatDn, 

thEre is no absolw guarartee oflhe accU'3cyoflhese calcolaions. 

Pnyquestims,corrments, concerns. ard suggestions, orw rEPOrt an error(s) in1he spreadsheet, 

please sEnd 3'1 Emal to nxi@lrc.govormxs3@lrc.gw. 

60 

60 
2-62

(b) Boundary Material: Gypsum Board

FDT : 02.2_Temperature_FV.xls s

CHAPTER 2. PREDICTING HOT GAS LAYER TEMPERATURE IN A ROOM 

FIRE WITH FORCED VENTILATION 

COMPARTMENT WITH THERMALLY THICK!THIN BOUNDARIES 

Version 1805.0 

The following calcolations estimate the hot gas layertemper.rure and smob layer height in enclosure ire. 

Parameters in YELLOW CELLS are Entered by the User. 

Parameters in GREEN CELLS are ALiomatically Selected from the DROP DOWN M ENUforthe Material Selected. 

All subsequent output wlues are calculated by1he spreadsheet and based on wlues specified in the input 

parameters. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a cell(s). 

The chapter in 1he NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

COMPARTMENT INFORMATION 

Compartment VlAdlh (w ) 16DO 1t 

Compartment Length 0.) 16DO 1t 

Compartment Height (h.) 12DO 1t 

lntenor Un•ng Th1ckness (6) 

AMBIENT CONDITIONS 

.Pmb ient Ptr Temper atiJ re (T ,.) nool·• 

Speci1ic Heat of ~r (c11) 11--__ ..:I.::O'::!Oit:J.t;g-K 

.AnbieM Ptr Oensity(p,) 1 1.18lt9fll 

THERMAL PROPERTIES 0 F COM PA RTM E NT ENCLOSING SURFACES 

Interior UninQ Thermal Inertia (kpc) 0.18 \WV ll c 

Interior Uning Thermal ConductiWy(k) 0.00017 1:v·v.t11 4< 

Interior Uning Specific Heat(c) 1.1 t;J.t;g-K 

Interior Uning Oensity(p) 960 1«1111 

Note. ~r density wIll autom<n•c:a lly correct w ilh .Anb1ent J:Cr T emperatiJre (T ,,) Input 

lHERMAL PROPERTIES FOR COivlviOIIIIITERIOR LIIIIIIG MATERIALS 

Material kf'C k c p 

(kVll.tn:t ·Kf -sec Whn-K\ 111<-"<•·K\ (kg An' ) 

..... tes .... 

3.66 .... 

0.01778 .... 

25.00 ~ 

2re.OO K 

Select Material 

I !lle;un Board ·I 

.Aiu minum (pure) 500 0.206 OS95 2710 Scroll to desired material t hen 

Steel (0.5" Carbon) 197 0.054 0.465 7850 Click on select ion 

Concrete 29 0.0016 0.75 2400 

Brick 1.7 0.0008 OS 2600 

Glass, Plate 16 0.00076 OS 2710 

Brick/Concrete Block 12 0.00073 OS4 1900 

Gypsum Board 0.18 0.00017 1.1 960 

Plywood 0.16 0.00012 25 540 

Fiber Insulation Board 0.16 0.00053 125 240 

Chipboard 0.15 0.00015 125 800 

.Aemed Conctet»l 0.12 0.00026 096 500 

Plasterboard 0.12 0.00016 OS4 950 

Calcium Silicate Board 0098 0.00013 1.12 700 

.Aiu mina Silicate Block 0036 0.00014 I 260 

Gla s:s Fiber hsulation 00018 0.000037 OS 60 

&:pan ded Polystve ne 0001 0.000034 15 20 

User Soecified \l.ilue Emr\I.Jiue Enter \l.ilue Enter \t.Jiue Enter \l.i lue 

" .... ,, " - . 0 
2-63

COMPARTMENT MASS VENTILATION FLOW RATE 

Forced Ventilation Flow Ral»l (m) 

FIRE SPECIFICATIONS 

1 000 DO lcn11 

Fire Heat Release Rate (Q) &IODO •:V\

1 

I Calculate I 

METHOD OF FOOTE, PAGNI, AND ALVARES (FPA) 

RH!I< •o: : s,:p E ,"'f<UidOO$. <:'! i:~ P :o 1?UUfl l,:~ ,•,:g J"" Edltb •, 2002, P ag; J-177 . 

Where lL ToJ = T oJ. T ~= upper layer gas temperature rise above ambient (K) 

T~= ambient air temperature (K) 

Q = heat releaser ate ofthe fire (kW) 

m = compartment mass ventilation flow rate (k9"sec) 

a.= specific heat of air (kJA<g·K) 

t.. = convective heat transfer coefficient (kW/m2-K) 

A:r= total area of the compartment enclosing surface boundaries (m') 

Thermal PEnetration Time Calculation 

~ = (PcoJI<)(orz/ 

Where t = thermal penetration time (sec) 

p =interior construction density (kg/m ~ 

C\> = interior construction heat capaci~ (kJA<g-l-9 

k =interior construction thermal conductivity(kW/m-1-9 

0 = in~rior construction thickness (m) 

t,. = 49:1.93 sec 

Hect Trcnsfer Coefficient Calculation 

1\: = v(kPclt) for t < t,. or (k/0) fort> t 

Where t.. = heattr ansfer coefficient(kW/mz·l-9 

kpc = in~rior construction thermal inertia (kW/mz-K)z·s ec 

(a thermal property tA material rc5pon5iblc tor the rate ottcmpcratl.uc ri5 c) 

t= time after ignition (sec) 

See table below for results 

Area of Co mp~ ment En dosing Surface Boundc.-ies 

kr= 2(wcx l:) +2 (hcxw.:) +2 (hex I:) 

Where Ar= total area of the compartment enclosing surface boundaries (ml 

w.: = compartment width (m) 

l: = compartment length (m) 

h.:= compartment height (m) 

A;= area of ventilation opening (ml 

Ar= 118.92 m.: 

Compartment Hot Gas layer Temperature With Force:! Ventilction 

lLToJIT~ = 0.63(0/ma. o{'z(tt kr/ma.)~ . .,~ 

lLToJ = ToJ· T~ 

ToJ = lLToJ+ T~ 

o .n2 111 A: c 

OSS9 tc C 
2-64

· lo l~ion It I AT0/T o 

I min) lsec) 

h,, ~~ ~~ ~~~) ~~~) 0 

1 

3 

4 

5 

10 

15 

40 

50 

55 

60 

" .05 

"' )3 

"' .03 

"' .02 

"' .01 

"' .01 

"" 

'"' "" '"' .01 

"" .01 

"" .01 

"" .01 

0.57 171.13 

0.70 208.55 

0.74 219.63 

0.77 228.64 

1.08 320.79 

1.08 320.79 

1.08 320.79 

1.08 320.79 

1.08 320.79 

1.08 320.79 

Hot Gas l ayer Ten1)el'ature 

Forced Ventilation- FPA Method 

29800 25.00 77.00 

469.13 196.13 385.04 

506.55 ~ 452.39 

51763 24463 472.34 

52664 25364 488.54 

618.79 345.79 654.43 

618.79 345.79 654.43 

~ :----

'---

618. 

618.79 345.79 654.43 

618.79 345.79 654.43 

618.79 345.79 654.43 

618.79 345.79 654.43 

~6oo 700 '=~ ====/ == == == == == == ==~==== == ==~ ~500 ------------------------------------------~ ~ 400 /' 

~300 c. ---------------------------------------------1 ~200 f-----------------------------------------------~ 

~100 ~ 

0 L-----------------------------------------~ 0 10 20 30 40 50 60 

Time (min) 
2-65

METHOD OF DEAL AND BEYLER 

RHn! •o: : s,:p E "iar.dOO~ .:o:r '~'> P .-o ~uu~ Ecg l.:.,; ,;on•.:g • J'" Edltb •, 2002. P ag; J-178. 

Heal: Trcnsfa- Coefficient Calculation 

tt: = 0.4v(kpc/tl fort< fl. 

Where 1\: = heattr ansfer coefficient(kW/mz· J.9 

kpc = in~rior construction thermal inertia (kW/m2

-K)z-s ec 

(a thermal property of material responsible for the rate oftemperab.ue rise) 

0 =thickness of interior lining (m) 

0.022 kW/m.:·K "· = 

Area of Co mpcrt ment En dosing Surface Bound~ies 

Ar= 2(w eX l:) + 2(h eX IA0 + 2(hcX l:) 

Ar= 118.92 m.: 

Compartment Hot Gas layer Temperature With Force:! Ventilction 

Where lL ToJ = T., • T ~=upper layer gas temperature rise above ambient (K) 

T~= ambient air temperature (K) 

Q = heat releaser ate ofthe fire (kW) 

m = compartment mass ventilation flow rate (k9"sec) 

C\> =specific heat of air (kJ/Kg-J.9 

1\: = convective heat transfer coefficient (kW/mz·K) 

Ar= total area of the compartment enclosing surface boundaries (m') 

·;me Aile' lon~ion (I} 

(min) (sec) (l<W~~ -K) ~~ ;~ (~~~ 0 . 298.00 25.00 

1 60 )2 158.01 4$.01 18301 

208. 508. 

~ 268. 

~ 29: 289. 314 

361. =$. jt= 437. 

462. 760 48C 

~ ~ ro8. 539: 

2700 5Z7. 552. 

50 =!! .00 539.08 837.08 $408 

60 .00 ~41 8$.41 $341 

(~;) 

n.oo 

36142 

451 

$0, 

598J 

~ 910: 

946.80 

1003.89 

1026.94 

~ 
2-66

1200 

~ 

1000 

t, 800 , 

~ 

~ 600 

• 

~ 

E 400 

,'!! 

200 

0 

0 

Summarvof ResUt 

1200 

1100 

1000 

900 ~ 

800 t, 

~ 700 

a 600 ~ 

1!1. 500 E 

~ • 400 

300 

200 

100 

0 

IJUIIM 

Hd Gas layer Temperature 

Forced \krrtilation · Deal and Be~erMethod 

......-

/ 

10 

_,-

./' 

J' / 

pr 

, 

0 10 

20 30 40 

Time (rrin) 

Hd Gas layer Temperature 

F' orced Ventilation 

-

20 30 

Time(min) 

50 

40 50 

The above calcolalionsare based on pinciples de'Wioped in1he SF'PE Haldbookof Fire A-otection 

&IQineerinQ, 3"' Ei::lition, 2002. 

C-'cutftims are based on certan assurrptDns ard have irherentlimitJ!ions. The results of such 

cabulaims may or may rm ha'W reasonaHe p-edictiw capabihies for a gi'Wn situaim, and should 

onlybe interp~d byal ilfonned user. 

Plthough each calcdalion in the spreadsheEt has been wi1ied with the results ofhand c-'cdatDn, 

thEre is no absolw guarartee oflhe accU'3cyoflhese calcolaions. 

Pnyquestims,corrments, concerns. ard suggestions, orw rEPOrt an error(s) in1he spreadsheet, 

please sEnd 3l Emal to nxi@lrc.govormxs3@lrc.gw. 

60 

~I'Q:I 

IH f.t~I'Q:I 

60 
2-67

Example Problem 2-5: Compartment with Forced Ventilation

Example Problem 2.16.2-2

Problem Statement

Consider c c c a compartment that is 12 ft wide x 10 ft long x 8 ft high (w x l x h ) with a vent opening

v v that is 3 ft wide x 7 ft tall (w x h ). The compartment boundaries are made of 0.5 ft thick gypsum

board. The forced ventilation rate is 800 cfm (exhaust). Calculate the hot gas layer temperature

in the compartment for a fire size of 300 kW at 2 minutes.

Solution

Purpose:

g

(1) Determine the hot gas layer temperature in the compartment (T ) at t = 2 min

after ignition.

Assumptions:

(1) Air properties (ambient) at 77 °F (25 °C)

(2) Simple rectangular geometry: no beam pockets

(3) One-dimensional heat flow through the compartment boundaries

(4) Constant Heat Release Rate (HRR)

(5) The fire is located at the center of the compartment or away from the walls

(6) The bottom of the vent is at the floor level

(7) The compartment is open to the outside at the inlet (pressure = 1 atm)
2-68

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 02.2_Temperature_FV.xls

Note: Since gypsum board thickness is more than 1 inch, it is required to use

correlations for thermally thick materials. Also, the spreadsheet has two different

methods to calculate the hot gas layer temperature. Both methods are presented for

comparison.

FDT Input Parameters: s

c

- Compartment Width (w ) = 12 ft

c

- Compartment Length (l ) = 10 ft

c

- Compartment Height (h ) = 8 ft

- Interior Lining Thickness (*) = 6 in

a

- Ambient Air Temperature (T ) = 77 °F

p

- Specific Heat of Air (c )= 1 kJ/kg-K

- Material: Select Gypsum Board on the FDTs

- Compartment Mass Ventilation Rate = 800 cfm

- Fire Heat Release Rate = 300 kW

Results*

Bounda gry Material Hot Layer Gas Temperature (T )

°C (°F)

Method of Foote, Pagni &

Alvares (FPA)

Method of Deal &

Beyler

Gypsum Board 216 (423) 256 (493)

 *see spreadsheet on next page at t = 2 min
2-69

Spreadsheet Calculations

FDT : 02.2_Temperature_FV.xls s

CHAPTER 2. PREDICTING HOT GAS LAYER TEMPERATURE IN A ROOM 

FIRE WITH FORCED VENTILATION 

COMPARTMENT WITH THERMALLY THICK!THIN BOUNDARIES 

Version 1805.0 

The following calcolations estimate the hot gas layertemper.rure and smob layer height in enclosure ire. 

Parameters in YELLOW CELLS are Entered by the User. 

Parameters in GREEN CELLS are ALiomatically Selected from the DROP DOWN M ENUforthe Material Selected. 

All subsequent output wlues are calculated by1he spreadsheet and based on wlues specified in the input 

parameters. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a cell(s). 

The chapter in 1he NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

COMPARTMENT INFORMATION 

Compartment VlAdlh (w ) 

Compartment Length 0.) 

Compartment Height (h.) 

lntenor Un•ng Th1ckness (6) 

AMBIENT CONDITIONS 

.Pmb ient Ptr Temper atiJ re (T ,.) 

Speci1ic Heat of ~r (c11) 

.Anb ient Ptr Density ( P,) 

THERMAL PROPERTIES 0 F COM PA RTM E NT ENCLOSING SURFACES 

Interior UninQ Thermal Inertia (kpc) 

Interior Uning Thermal ConductiWy(k) 

Interior Uning Specific Heat(c) 

Interior Uning Oensity(p) 

~Note:~~~~ 

12DO 1t 

1 ODO 1t 

SDO 1t 

1----..:I.::D'::IO I:J.t;g-1< 

1.18 t;gfll 

3.60 Ill 

J£i5 111 

2.U 111 

25.00 ~ 

2re.OO K 
2-70

COMPARTMENT MASS VENTILATION FLOW RATE 

Forced Ventilation Flow Ral»l (m) 

FIRE SPECIFICATIONS 

eoooolcn11 

Fire Heat Release Rate (Q) 3:1000 •:V\

1 

I Calculate I 

METHOD OF FOOTE, PAGNI, AND ALVARES (FPA) 

RH!I< •o: : s,:p E ,"'f<UidOO$. <:'! i:~ P :o 1?UUfl l,:~ ,•,:g J"" Edltb •, 2002, P ag; J-177 . 

Where lL ToJ = T oJ. T ~= upper layer gas temperature rise above ambient (K) 

T~= ambient air temperature (K) 

Q = heat releaser ate ofthe fire (kW) 

m = compartment mass ventilation flow rate (k9"sec) 

a.= specific heat of air (kJA<g·K) 

t.. = convective heat transfer coefficient (kW/m2-K) 

A:r= total area of the compartment enclosing surface boundaries (m') 

Thermal PEnetration Time Calculation 

~ = (PcoJI<)(orz/ 

Where t = thermal penetration time (sec) 

p =interior construction density (kg/m ~ 

C\> = interior construction heat capaci~ (kJA<g-l-9 

k =interior construction thermal conductivity(kW/m-1-9 

0 = in~rior construction thickness (m) 

t,. = 36068.24 sec 

Hect Trcnsfer Coefficient Calculation 

1\: = v(kPclt) for t < t,. or (k/0) fort> t 

Where t.. = heattr ansfer coefficient(kW/mz·l-9 

kpc = in~rior construction thermal inertia (kW/mz-K)z·s ec 

(a thermal property tA material rc5pon5iblc tor the rate ottcmpcratl.uc ri5 c) 

t= time after ignition (sec) 

See table below for results 

Area of Co mp~ ment En dosing Surface Boundc.-ies 

kr= 2(wcx l:) +2 (hcxw.:) +2 (hex I:) 

Where Ar= total area of the compartment enclosing surface boundaries (ml 

w.: = compartment width (m) 

l: = compartment length (m) 

h.:= compartment height (m) 

A;= area of ventilation opening (ml 

Ar= 55.00 m.: 

Compartment Hot Gas layer Temperature With Force:! Ventilction 

lLToJIT~ = 0.63(0/ma. o{'z(tt kr/ma.)~ . .,~ 

lLToJ = ToJ· T~ 

ToJ = lLToJ+ T~ 

0.378 111 A: c 

O.U7 tc C 
2-71

· lo l~ion It I AT0/T o 

I min) lsec) 

h,, ~~ ~~ ~~~) ~~~) 0 

1 

3 

4 

5 

10 

15 

40 

50 

55 

60 

" .05 

"' )3 

"' .03 

"' .02 

"' )2 

"' .01 

"" 

'"' "" '"' .01 

"" .01 

"" .01 

"" .01 

0.57 169.45 

0.69 206.50 

0.73 217.48 

0.76 226.39 

0.86 256.47 

0.93 275.89 

=i. 

321. 

1.10 329.17 

1.15 342.66 

1.17 348.58 

1.19 354.09 

Hot Gas l ayer Ten1)el'ature 

Forced Ventilation- FPA Method 

29800 25.00 77.00 

487A5 194A5 382.01 

504.50 231.50 448.71 

515A8 242A8 468.46 

52439 25139 484.50 

554A7 

573.89 

588, 315J 

300.89 

281A" 

~ 

~f- 610 331 

619. 346; ~:---- 627.17 354.17 669.50 

64066 36766 693.78 

646.59 373.59 704.46 

65209 37909 714.36 

800 .----------------------------------------------, 

~700 ~==::== ~~::====~ ================== ~ t. 600 

~ 500 ./" 

~400 ~~------------------------------------------~ 

~300 w-------------------------------------------------1 ~200 J-------------------------------------------------1 ~ 

100 ----------------------------------------------~ 

0 L-----------------------------------------~ 0 10 20 30 40 50 60 

Time (min) 
2-72

METHOD OF DEAL AND BEYLER 

RHn! •o: : s,:p E "iar.dOO~ .:o:r '~'> P .-o ~uu~ Ecg l.:.,; ,;on•.:g • J'" Edltb •, 2002. P ag; J-178. 

Heal: Trcnsfa- Coefficient Calculation 

tt: = 0.4v(kpc/tl fort< fl. 

Where 1\: = heattr ansfer coefficient(kW/mz· J.9 

kpc = in~rior construction thermal inertia (kW/m2

-K)z-s ec 

(a thermal property of material responsible for the rate oftemperab.ue rise) 

0 =thickness of interior lining (m) 

0.022 kW/m.:·K "· = 

Area of Co mpcrt ment En dosing Surface Bound~ies 

Ar= 2(w eX l:) + 2(h eX IA0 + 2(hcX l:) 

Ar= 55.00 m.: 

Compartment Hot Gas layer Temperature With Force:! Ventilction 

Where 

·;me Aile' 

(min) 

0 

lL ToJ = T., • T ~=upper layer gas temperature rise above ambient (K) 

T~= ambient air temperature (K) 

Q = heat releaser ate ofthe fire (kW) 

m = compartment mass ventilation flow rate (k9"sec) 

C\> =specific heat of air (kJ/Kg-J.9 

1\: = convective heat transfer coefficient (kW/mz·K) 

Ar= total area of the compartment enclosing surface boundaries (m') 

lon~ion (I} 

(sec) (l<W~~ -K) ~~ ;~ . 298.00 

(~~~ 25.00 

1 60 )2 181.58 479.58 206.58 

=i. =!! 255: 

310 

304. 602. 329. 

~ ~ 387. 44: 

435. 733. 460 

~ i. ;----

'----

2700 '76. 

50 =!! .00 485.71 783.71 

60 .00 497.1l3 795.1l3 ~:: 

(~;) 

n.oo 

403.84 

492J 

591 

624 

~ 861 

~ 938• 

=!!= 
2-73

1200 

~ 

1000 

t, 800 , 

e 

~ 600 

• 

~ 

E 400 

~ • 

200 

0 

0 

Summarvof ResUt 

1100 

1000 

900 

E 

800 

700 

e 600 ~ ~ 500 ~ 

E 400 ~ • 

300 

200 

100 

0 

Hd Gas layer Temperature 

Forced \krrtilation · Deal and Be~erMethod 

/ 

---

10 

_,. 

; 

(/ 

0 10 

20 30 40 

Time (rrin) 

Hd Gas layer Temperature 

F' orced Ventilation 

20 30 

Time(min) 

50 

40 50 

The above calcolalionsare based on pinciples de'Wioped in1he SF'PE Haldbookof Fire A-otection 

&IQineerinQ, 3"' Ei::lition, 2002. 

C-'cutftims are based on certan assurrptDns ard have irherentlimitJ!ions. The results of such 

cabulaims may or may rm ha'W reasonaHe p-edictiw capabihies for a gi'Wn situaim, and should 

onlybe int:erp~d byal ilfonned user. 

Plthough each calcdalion in the spreadsheEt has been wi1ied with the results ofhand c-'cdatDn, 

thEre is no absolw guarartee oflhe accU'3cyoflhese calcolaions. 

Pnyquestims,corrments, concerns. ard suggestions, orw rEPOrt an error(s) in1he spreadsheet, please send 3'1 emaJ w nxi@lrc.govormxs3@lrc.gw. 

60 

60 
2-74

Problem 2.16.2-3

Problem Statement

Consider c c c a compartment that is 8 ft wide x 8 ft long x 6 ft high (w x l x h ). The compartment

boundaries are made of 0.75 ft thick brick. The forced ventilation rate is 400 cfm (exhaust).

Calculate the hot gas layer temperature in the compartment for a fire size of 500 kW at 2 minutes.

Example Problem 2-6: Compartment with Forced Ventilation

Solution

Purpose:

g

(1) Determine the hot gas layer temperature in the compartment (T ) at t = 2 min after

ignition.

Assumptions:

(1) Air properties (ambient) at 77 °F (25 °C)

(2) Simple rectangular geometry (no beam pockets)

(3) One-dimensional heat flow through the compartment boundaries

(4) Constant Heat Release Rate (HRR)

(5) The fire is located at the center of the compartment or away from the walls

(6) The bottom of the vent is at the floor level

(7) The compartment is open to the outside at the inlet (pressure = 1 atm)
2-75

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 02.2_Temperature_FV.xls

Note: Since the interior lining material thickness is more than 1 inch, it is required to use

correlations for thermally thick materials. Also, the spreadsheet has two different

methods to calculate the hot gas layer temperature. We are going to use both methods

to compare values.

FDT Input Parameters: s

c

- Compartment Width (w ) = 8 ft

c

- Compartment Length (l ) = 8 ft

c

- Compartment Height (h ) = 6 ft

- Interior Lining Thickness (*) = 9 in

a

- Ambient Air Temperature (T ) = 77 °F

p

- Specific Heat of Air (c )= 1 kJ/kg-K

- Material: Select Brick on the FDTs

- Compartment Mass Ventilation Rate = 400 cfm

- Fire Heat Release Rate = 500 kW

Results*

Bounda gry Material Hot Layer Gas Temperature (T )

°C (°F)

Method of Foote, Pagni &

Alvares (FPA)

Method of Deal &

Beyler

Brick 321 (611) 330 (626)

*see spreadsheet on next page at t = 2 min.
2-76

Spreadsheet Calculations

FDT : 02.2_Temperature_FV.xls s

CHAPTER 2. PREDICTING HOT GAS LAYER TEMPERATURE IN A ROOM 

FIRE WITH FORCED VENTILATION 

COMPARTMENT WITH THERMALLY THICK!THIN BOUNDARIES 

Version 1805.0 

The following calcolations estimate the hot gas layertemper.rure and smob layer height in enclosure ire. 

Parameters in YELLOW CELLS are Entered by the User. 

Parameters in GREEN CELLS are ALiomatically Selected from the DROP DOWN M ENUforthe Material Selected. 

All subsequent output wlues are calculated by1he spreadsheet and based on wlues specified in the input 

parameters. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a cell(s). 

The chapter in 1he NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

COMPARTMENT INFORMATION 

Compartment VlAdlh (w ) 

Compartment Length 0.) 

Compartment Height (h.) 

lntenor Un•ng Th1ckness (6) 

AMBIENT CONDITIONS 

.Pmb ient Ptr Temper atiJ re (T ,.) 

Speci1ic Heat of ~r (c11) 

.Anb ient Ptr Density ( P,) 

THERMAL PROPERTIES 0 F COM PA RTM E NT ENCLOSING SURFACES 

Interior UninQ Thermal Inertia (kpc) 

Interior Uning Thermal ConductiWy(k) 

Interior Uning Specific Heat(c) 

Interior Uning Oensity(p) 

~Note:~~~~ 

SDO 1t 

SDO 1t 

6DO 1t 

1----..:I.::D'::IO I:J.t;g-1< 

1.18 t;gfll 

2.U Ill 

2.U 111 

1.83 .... 

Oz:e6 Ill 

25.00 ~ 

2re.OO K 

Materia 

on select ion 
2-77

COMPARTMENT MASS VENTILATION FLOW RATE 

Forced Ventilation Flow Ral»l (m) 

FIRE SPECIFICATIONS 

4lODOicnll 

Fire Heat Release Rate (Q) &IODO •:V\

1 

I Calculate I 

METHOD OF FOOTE, PAGNI, AND ALVARES (FPA) 

RH!I< •o: : s,:p E ,"'f<UidOO$. <:'! i:~ P :o 1?UUfl l,:~ ,•,:g J"" Edltb •, 2002, P ag; J-177 . 

Where lL ToJ = T oJ. T ~= upper layer gas temperature rise above ambient (K) 

T~= ambient air temperature (K) 

Q = heat releaser ate ofthe fire (kW) 

m = compartment mass ventilation flow rate (k9"sec) 

a.= specific heat of air (kJA<g·K) 

t.. = convective heat transfer coefficient (kW/m2-K) 

A:r= total area of the compartment enclosing surface boundaries (m') 

Thermal PEnetration Time Calculation 

~ = (PcoJI<)(orz/ 

Where t = thermal penetration time (sec) 

p =interior construction density (kg/m ~ 

C\> = interior construction heat capaci~ (kJA<g-l-9 

k =interior construction thermal conductivity(kW/m-1-9 

0 = in~rior construction thickness (m) 

t,.= 33967.67 sec 

Hect Trcnsfer Coefficient Calculation 

1\: = v(kPclt) for t < t,. or (k/0) fort> t 

Where t.. = heattr ansfer coefficient(kW/mz·l-9 

kpc = in~rior construction thermal inertia (kW/mz-K)z·s ec 

(a thermal property tA material rc5pon5iblc tor the rate ottcmpcratl.uc ri5 c) 

t= time after ignition (sec) 

See table below for results 

Area of Co mp~ ment En dosing Surface Boundc.-ies 

kr= 2(wcx l:) +2 (hcxw.:) +2 (hex I:) 

Where Ar= total area of the compartment enclosing surface boundaries (ml 

w.: = compartment width (m) 

l: = compartment length (m) 

h.:= compartment height (m) 

A;= area of ventilation opening (ml 

Ar= 29.73 m.: 

Compartment Hot Gas layer Temperature With Force:! Ventilction 

lLToJIT~ = 0.63(0/ma. o{'z(tt kr/ma.)~ . .,~ 

lLToJ = ToJ· T~ 

ToJ = lLToJ+ T~ 

0 .189 111 A: c 

0224 tC C 
2-78

!i!!!!:Atter ~ l~ion(t] .,'2, or;r, 

~ T, 

(n in) (sec) (~C) (~ ) 0 . ...:._ 29 77DO 

~ '---

'---

"' 681 

:! !----~ 

'"' 884 

,; .. 911 

=li '---

;-

"" ,..--

;---

'-

Hot Gas Layer Terrperature 

Forced Ventilation · FPA Method 

1200 

E 1ooo 

; 800 

• ;;; 600 ~ 

~ 

E 400 

~ • 200 

0 

0 10 20 30 40 5) eo 

Time (min) 
2-79

METHOD OF DEAL AND BEYLER 

RHn! •o: : s,:p E "iar.dOO~ .:o:r '~'> P .-o ~uu~ Ecg l.:.,; ,;on•.:g • J'" Edltb •, 2002. P ag; J-178. 

Heal: Trcnsfa- Coefficient Calculation 

tt: = 0.4v(kpc/tl fort< fl. 

Where 1\: = heattr ansfer coefficient(kW/mz· J.9 

kpc = in~rior construction thermal inertia (kW/m2

-K)z-s ec 

(a thermal property of material responsible for the rate oftemperab.ue rise) 

0 =thickness of interior lining (m) 

0.067 kW/m.:·K "· = 

Area of Co mpcrt ment En dosing Surface Bound~ies 

Ar= 2(w eX l:) + 2(h eX IA0 + 2(hcX l:) 

Ar= 29.73 m.: 

Compartment Hot Gas layer Temperature With Force:! Ventilction 

Where lL ToJ = T., • T ~=upper layer gas temperature rise above ambient (K) 

T~= ambient air temperature (K) 

Q = heat releaser ate ofthe fire (kW) 

m = compartment mass ventilation flow rate (k9"sec) 

C\> =specific heat of air (kJ/Kg-J.9 

1\: = convective heat transfer coefficient (kW/mz·K) 

Ar= total area of the compartment enclosing surface boundaries (m') 

·;me Afte' lon~ion (I l 

(min) (sec) 

0 . 298.00 25.00 

1 60 )7 224.69 522.69 24969 

446. 744. 471 

583. 881. 608. 

744. 104:< 789: 

801. 1099 826. 

ff73. 

950 

2700 957. 255. 982: 

50 .01 986.78 1284.78 

1~~r 60 .01 1037.!7 1335.!7 103227 

n.oo 

48144 

881 

1801 

1853.21 

1944.09 
2-80

2!ll0 

<:' 2000 

'-' 

~ 1!ll0 i 1000 

,'!!. !nO 

fii,,,,dii.';@il 

0 

0 

2200 

2000 

1800 

if:' 1600 

-1400 

11200 

~ 1000 

GO 800 ~ 

600 

400 

200 

0 

+ !.JiM 

li:t Gas Layer Temperah.re 

Forced \kntilati:ln • Deal and Be~er Mettod 

_,-

/ 

10 20 

....-

./' 

/ 

, 

0 10 

30 40 

Time (rrin) 

1-bt Gas Laye- Temperal:ure 

Forced \kntilalion 

-

30 

Time (rrin) 

50 

40 50 

Th abov~ ca II.'IO,_ $ all? b.'IHdoa pill C.) .. $ < .. ~• =*d Ia 1U S fPf H.'la<lbocf; 01 Fh PI ~C1JH 

fa U~ ~~ 111<1. J " f<Uim .2002. 

c at:1 1.10' " a~~ baad oa o:1t111 a sH•IIPO' " a ad ~ "• ~ ~eat 1111 nao,., . Th I? Hit oTHc• 

cat:U.'Itbu mayo1m<rv w~ r~a soa., l: pr~dt:U ~ cal:..'lbllll»$ Tor a giJ~ a $ltlla\Da. aHI ' ' o••:l ., b~ ll,lpl?,dl)"f a a IH PII ~d 16U . 

. :..u o•g• ~<t • cat:1 1.10H 111u P'~aoa~~ a. b~~ a ~1M!d wiG 1u r~H It on a ad cat:ll.'ltba. lUI~ 1$ ao al:r;on g1araah TU~ <t:CII<t'f TU~ $~ ca•:II.'IO,.$ . 

. :. r>{ 0,. $.COIIIIII ~ abc.coao: '"·aad H9J~ 0H6. Olb l~p rtaa ~11 (') 111U p1M I$h~t 

a.~ d a a 111 ll b nl@a c .g,v OIIIIU 3€J:uc.gw . 

60 

-- 'AI. ""! - ... : ~ '·"'" : 
The heat release rate may be thought of as the “power” of the fire and is some times referred to as 1

fire “power.”

3-1

CHAPTER 3. ESTIMATING BURNING CHARACTERISTICS 

OF LIQUID POOL FIRE, HEAT RELEASE RATE, BURNING DURATION,

AND FLAME HEIGHT

3.1 Objectives

This chapter has the following objectives:

• Identify the predominant flammable material in a nuclear power plant (NPP).

• Introduce the methods that are used to estimate the heat release rate.

• Identify the factors that influence the heat release rate and burning rate.

• Explain how to analyze pool fires in NPPs.

• Explain how to analyze the burning duration of pool fires.

• Identify the zones of a candle and the categories of a flame.

• Describe the importance of ceiling configurations.

• Explain turbulent diffusion flames.

• Introduce the factors that determine how fast an object will heat.

• Define relevant terms, including heat release rate, heat of combustion, burning duration,

flame height, adiabatic flame, laminar, and turbulent flames.

3.2 Heat Release Rate

Fire development is generally characterized in terms of heat release rate (HRR) vs. time.

Thus, determining the HRR (or burning rate) is an essential aspect of a fire hazard analysis (FHA). 1

The relationship between HRR (or ) and time for a certain scenario is termed the design fire curve

for that scenario, as illustrated in Figure 3-1.

For a routine FHA, it is acceptable to broadly approximate the burning rates (HRRs). For instance,

post-flashover structure analyses are often based on the fire duration or severity associated with

an aggregate fuel loading (combustible load per unit floor area). However, if it is essential to

estimate specific fire effects within an enclosure, it is essential to more accurately determine the

burning rate characteristics (i.e., HRR history).

The HRR is not a fundamental property of a fuel and, therefore, cannot be calculated from the basic

material properties. It is usually determined from testing. Table 3-1 lists some HRR characteristic

values obtained by burning various fuel packages and recording the heat output from various

sources. Estimates of fire source intensities (i.e., HRR) can be based either on direct

measurements of the burning rates of similar large fuel configurations or the extrapolation of smallscale test data obtained under simulated thermal conditions. In the absence of measured HRR

data, the fire protection engineer (FPE) must estimate the HRR history for a particular fuel. While

not as accurate as laboratory testing, sufficient information exists in the literature to permit

estimates of initial fire growth, peak burning rates, and fire duration for various fuels and fuel

geometries.
3-2

Figure 3-1 A Simple Design Fire Curve

Table 3-1. Rough Measure of Heat Generated from Various Sources

(Karlsson and Quintiere, 1999, © CRC Press, LLC. With permission.)

Fuel Heat Release Rate

A burning cigarette 5 W

A typical light bulb 60 W

A burning candle 80 W

A human being at normal exertion 100 W

A burning wastepaper basket 100 kW

A burning 1 m2 pool of gasoline 2.5 MW

Burning wood pallets, stacked to a height of 3 m 7 MW

Burning polystyrene jars, in 2 m cartons 4.9 m high 30–40 MW 2

Output from a typical reactor at an NPP 3,250–3,411 MW

Note: 1 kW = 1,000 W and 1 MW = 1,000 kW
3-3

Various studies (Lee, 1985, Nowlen, 1986, and 1987, Chavez, 1987, and Babrauskas, 1991) have

measured and reported representative unit HRR values for a number of fuels present in an NPP,

such as electrical cables, electrical cabinets, and transient combustibles (e.g.,

flammable/combustible liquids and trash). Flammable/combustible liquid spill fires and trash fires

are the most commonly postulated transient fuel exposure fires, while electrical cable and cabinet

fires are the most commonly postulated fixed fuel fires in NPPs. In fact, the plastic insulation and

jackets on electrical cables are usually the predominant flammable material in an NPP.

The most common method to measure HRR is known as “oxygen consumption calorimetry”

(ASTM E1354). The basis of this method is that most gases, liquids, and solids release a constant

amount of energy for each unit mass of oxygen consumed. This constant has been found to be

13,100 kJ/kg oxygen consumed and is considered to be accurate within ±5 percent for most

hydrocarbon fuels. After ignition, all of the combustion products are collected in a hood and

removed through an exhaust duct in which the flow rate and composition of the gases is measured

to determine how much oxygen has been used for combustion. The HRR then can be computed

using the constant relationship between oxygen consumed and energy released.

Another common method of assessing HRR is to measure the burning rate, which is also known

as the mass loss rate. This is done by weighing the fuel package as it burns, using weighing

devices or a load cell. Estimating the HRR based on the mass loss rate requires knowledge of the

effective heat of combustion. The HRR is then calculated using the following equation:

 (3-1)

Where:

 = heat release rate (kW)

 = burning or mass loss rate (kg/sec)

Hc,eff = effective heat of combustion (kJ/kg)

The average burning rates for many products and materials have been experimentally determined

in free-burning tests. For many materials, the burning rate is reported per horizontal burning area

in units of kg/m -sec. If the area of the fuel and the effective heat of combustion are known, the 2

above equation becomes:

 (3-2)

Where:

 = burning or mass loss rate per unit area per unit time (kg/m -sec) 2

Af = horizontal burning area of the fuel (m )

2

k$= empirical constant (m )

-1

D = diameter of burning area (m)
3-4

The average burning rate per unit area per unit time, heat of combustion, and fuel-specific

properties have been tabulated for a number of different fuels. (See Table 3-2 for free-burning fire

characteristics of various fuels.)

Table 3-2. Large-Pool Fire Burning Rate Data

(Babrauskas, 2002, © SFPE. With permission.)

Material Mass Loss

Rate

(kg/m -sec) 2

Heat of

Combustion

H c, eff

(kJ/kg)

Density

(kg/m )

3

Empirical

Constant

k$

(m )

-1

Cryogenics

2

 Liquid H

4

 LNG (mostly CH )

3 8 LPG (mostly C H ) 

0.017

0.078

0.099

12,000

50,000

46,000

70

415

585

6.1

1.1

1.4

Alcohols

3

 Methanol (CH OH)

2 5 Ethanol (C H OH)

0.017

0.015

20,000

26,800

796

794

100 **

100 **

Simple Organic Fuels

4 10

 Butane (C H )

6 6 Benzene (C H )

6 14

 Hexane (C H )

7 16

 Heptane (C H )

8 10

 Xylene (C H )

3 6 Acetone (C H O)

4 8 2 Dioxane (C H O )

4 10

 Diethyl ether (C H O)

0.078

0.085

0.074

0.101

0.090

0.041

0.018

0.085

45,700

40,100

44,700

44,600

40,800

25,800

26,200

34,200

573

874

650

675

870

791

1,035

714

2.7

2.7

1.9

1.1

1.4

1.9

5.4

0.7

Petroleum Products

 Benzine

 Gasoline

 Kerosene

 JP-4

 JP-5

 Transformer Oil, hydrocarbon

 Fuel Oil, heavy

 Crude Oil

0.048

0.055

0.039

0.051

0.054

0.039

0.035

0.022–0.045

44,700

43,700

43,200

43,500

43,000

46,400

39,700

42,500–42,700

740

740

820

760

810

760

940–1,000

830–880

3.6

2.1

3.5

3.6

1.6

0.7

1.7

2.8

Solids

 Polymethylmethacrylate

5 8 2 n

(C H O )

3 6 n

 Polypropylene (C H )

8 8 n

 Polystyrene (C H )

0.020

0.018

0.034

24,900

43,200

39,700

1,184

905

1,050

3.3

100 **

100 **

Miscellaneous

561 Silicon Transformer Fluid ®

0.005 28,100 960 100 **

** these values are to be used only for computation purposes; the true values are unknown.
3-5

The effective heat of combustion (sometimes called the chemical heat of combustion) is a measure

of how much energy is released when a unit mass of material is oxidized. This value is typically

given in kJ/kg. It is important to distinguish between the complete heat of combustion and the

effective heat of combustion. The complete heat of combustion is the measure of energy released

when combustion is complete, leaving no residual fuel and releasing all of the chemical energy of

the material. The effective heat of combustion is more appropriate for a fire in which combustion

is not necessarily complete and some residue remains. This is also sometimes termed the

chemical heat of combustion.

For example, Babrauskas (1983 and 1986) distinguishes four burning modes of pool fires as

defined by size in Table 3-3.

Table 3-3. Pool Fire Burning Modes

Pool Fire Diameter (m) Burning Mode

<0.05 (2 in) Convective, laminar

<0.2 (8 in) Convective, turbulent

0.2 to 1.0 (8 in to 3.3 ft) Radiative, optically thin

>1.0 (3.3 ft) Radiative, optically thick

3.2.1 Enclosure Effects on Mass Loss Rate

When an object (fuel) burns inside a compartment, the two main factors that influence the fire

growth are energy released and burning or mass loss rate of the fuel. The smoke and hot gases

will accumulate at the compartment ceiling level and heat the compartment boundaries (ceiling and

walls). These compartment boundary surfaces and the hot gases radiate heat toward the fuel

surface, thereby increasing the fuel burning rate. Second, the compartment openings (doors,

windows, and other leakage areas) may restrict the availability of oxygen needed for combustion,

thereby decreasing the amount of fuel consumed and increasing in the concentration of unburned

gases. If the ventilation opening is small, the limited availability of oxygen causes incomplete

combustion, thereby decreasing the HRR, which in turn reduces the gas temperature and heat

transfer to the fuel surface, while the fuel continues to release volatile gases at a similar or

somewhat lower rate. When partial combustion of the gases occurs within the compartment, the

gas leaving the compartment mixes with oxygen and flames appear at the ventilation opening. In

summary, compartment heat transfer can increase the burning or mass loss rate of the fuel, while

compartment ventilation of the available air near the floor decreases the mass loss rate.

3.2.2 Pool Fires

A pool fire involves a horizontal, upward-facing, combustible fuel. The term implies the fuel in the

liquid phase (pool), but it can also apply to flat slabs of solids fuels which decompose in a manner

similar to liquids [e.g., Polymethylmethacrylate (PMMA or Plexiglass) and Polyethylene (PE)]. Liquid

fuel may burn in an open storage container or on the ground in the form of a spill. For a given

amount of fuel, spills with a large surface area burn with a high HRR for a short duration, and spills

with a smaller surface area burn with a lower HRR for a longer duration. When spilled, the

flammable/combustible liquid may form a pool of any shape and thickness, and may be controlled
3-6

by the confinement of the area geometry such as a dike or curbing. Once ignited, a pool fire

spreads rapidly over the surface of the liquid spill area. The burning rate of a given fuel can also

be affected by its substrate (i.e., gravel and sand) in a spill. For flammable/combustible liquids,

flame spread rates range from approximately 10 cm/sec (4 in/sec) to 2 m/sec (6.6 ft/sec). Pool fires

in NPPs can result from leakage of the reactor coolant pump (RCP) at the gland or the seal,

oil spill from electrical transformers, and pumps or fuel spray from pipe flanges on equipment such

as standby diesel generator (SBDGs). Transient fuels such as liquids used for cleaning and

painting are sources of pool fire in an NPP. Figure 3-2 depicts the dynamic feature of a pool fire.

Table 3-4 summarizes the burning rate of combustible liquids and solids found in typical NPPs.

Table 3-4. Burning Rates of Some Common Combustible Materials

Found in Nuclear Power Plants*

Fuel Mass Burning Rate

(kg/m -sec) 2

Heat of Combustion

H , c eff

(kJ/kg)

Density

(kg/m )

3

Cable Materials

PE/PVC

XPE/FRXPE

XPE/Neoprene

PE, PP/Cl.S.PE

FRXPE/Cl.S.PE

PE, Nylon/PVC, Nylon

Silicone, glass braid, asbestos

XPE/XPE

FEP - TeflonTM

ETFE - TefzelTM 

0.0044

0.0037

0.0043

0.0026

0.0033

0.0034

0.0045

0.0044

0.007

0.014

25,100

28,300

10,300

26,800

17,300

10,200

24,000

12,500

3,200

12,600 

-

-

-

-

-

-

-

-

-

-

Flammable/Combustible Liquid

Diesel Oil

Gasoline

Kerosene

Transformer Oil

Lube Oil (used in RCP motors and

turbine lubrication)**

0.044

0.055

0.039

0.039

- 

44,400

43,700

43,200

46,000

- 

918

740

820

760

- 

Cellulose Material

Wood 0.055 13,000–15,000 420–640

*Empirical constants (k$) are unknown. Use k$ = 100m as a conservative estimate. -1

**For lubricating oil, use properties of transformer oil (has similar burning characteristics).

CL.S.PE-Chlorosulfonated Polyethylene; FR-Fire Retardant; PE-Polyethylene; PP-Polypropylene; 

PVC-Polyvinylchloride; TeflonTM - FEP-Fluorinated Polyethylene- Propylene; 

TefzelTM- ETFE-Ethylenetetrafluoroethylene; XLPE-Crosslinked Polyethylene.
3-7

Figure 3-2 Dynamic Features of a Pool Fire

3.3 Burning Duration

The burning rate of a given fuel is controlled by both its chemistry and its form. Fuel chemistry

refers to its composition (e.g., cellulosic vs. petrochemical). Common cellulosic materials include

wood, paper, cotton, and fabric. Petrochemical materials include liquids or plastics that are largely

petroleum based. The form (or shape) of the fuel material also has an effect on its burning rate.

A particularly important form factor is the surface area to mass ratio of the fuel, which is defined as

the surface area available to combust as compared to the total mass of the material.

The concept of burning duration is a way of characterizing the hazard of a compartment fire in

terms of the length of time the fuel in the compartment could be expected to burn, which depends

on the total amount of fuel available. Fuel loading is the concept that describes the expected

burning duration, provided that the necessary amount of air is available (i.e., fuel-controlled fire).

A fire burning at a constant HRR consumes fuel mass at a constant rate. Thus, the mass of

material being burned per second and the amount of material available to be consumed, it is

possible to estimate the total burning duration of a fuel.
3-8

3.3.1 Burning Duration of a Pool Fire

When a spilled liquid is ignited, a pool fire develops. Provided that an ample supply of oxygen is

available, the amount of surface area of the given liquid becomes the defining parameter. The

diameter of the pool fire depends upon the release mode, release quantity (or rate), and burning

rate. In some instances, the spill is unrestricted by curbs or dikes, allowing it to spread across the

ground and establish a large exposed surface area. Liquid pool fires with a given amount of fuel

can burn for long periods of time if they have a small surface area, or for short periods of time over

a large spill area. For a fixed mass or volume of flammable/combustible liquid, the burning duration

b

(t ) for the pool fire is estimated using the following expression:

 (3-3)

Where:

V = volume of liquid (gallons or m )

3

D = pool diameter (m)

 = regression rate (m/sec)

As a pool of liquid combusts and the fuel is consumed, its depth decreases. The rate of burning,

also called the regression rate ( ), is defined as a volumetric loss of liquid per unit surface area of

the pool per unit time, as illustrated by the following expression:

 (3-4)

Where:

 = mass burning rate of fuel per unit area (kg/m -sec) 2

 = liquid fuel density (kg/m )

3

3.4 Flame Height

A flame is a body or stream of gaseous material involved in the combustion process, which emits

radiant energy at specific wavelength bands depending on the combustion chemistry of the fuel

involved. In most cases, some portion of the emitted radiant energy is visible to the human eye as

the glowing, gaseous portion of a fire, which is typically referred to as its flame.

The flame generally consists of a mixture of oxygen (air) and another gas, typically a combustible

substance such as hydrogen, carbon monoxide, or a hydrocarbon. The brightest flames are not

always the hottest. For example, hydrogen exhibits a high flame temperature. However it

combines with oxygen when burning to form water, hydrogen has an almost invisible flame under

ordinary circumstances. When hydrogen is absolutely pure and the air around it is completely free

of dust, the hydrogen flame cannot be seen, even in a dark room.

In order to gain a better understanding of flames, a burning candle can be used as an example.

When the candle is lit, the heat of the match melts the wax, which is carried up the wick and

vaporized by the heat. As it is broken down by the heat, the vaporized wax combines with the

oxygen of the surrounding air and produces heat and light in the form of a flame. The candle flame
3-9

consists of three zones, which are easily distinguished. The innermost, nonluminous zone is

composed of a gas/air mixture at a comparatively low temperature. In the second luminous zone,

hydrogen (H2) and carbon monoxide (CO) (two of many products from the decomposition of the

wax 2) react with oxygen to form combustion products, which include water (H O) and carbon dioxide

2

(CO ). In this zone, the temperature of the flame is 590–680 °C (1,094–1,256 °F), which is

sufficiently intense to dissociate the gases in the flame and produce free carbon particles. These

particles are heated to incandescence and then consumed. Outside the luminous zone is a third,

2

invisible zone in which the remaining CO and H are finally consumed. This zone is not visible to

the human eye. Figure 3-3 shows the temperature distribution through the flame of a burning candle.

Figure 3-3 Temperature Distribution in the Flame of a Burning Candle

All combustible substances require a finite amount of oxygen for complete burning. (A flame

can be sustained in an atmosphere of pure chlorine, but combustion cannot complete.) In the

burning of a candle or solids such as wood or coal, the surrounding atmosphere supplies this

oxygen. In gas burners, air or pure oxygen is mixed with the gas at the base of the burner so

that the carbon is consumed almost instantaneously at the mouth of the burner. This is an

example of a premixed flame. The hottest portion of the flame of a Bunsen burner has a

temperature of approximately 1,600 °C (2,912 °F). By contrast, the hottest portion of the

oxygen-acetylene flames (torch) used for cutting and welding metals reaches approximately

3,500 °C (6,330 °F) because the increased oxygen in the case of the torch yields a significantly

higher flame temperature. Any time the oxygen rate is increased (e.g., wind- or airflow-aided

combustion or an oxygen-enriched atmosphere), the temperatures obtained will be higher than

for the fuel combusting in a normal atmosphere.
3-10

A flame can be thought of in two distinct categories, including diffusion flame (Figure 3-4) and

premixed flame (Figure 3-5). A diffusion flame is one in which the fuel and oxygen are

transported (diffused) from opposite sides of the reaction zone (flame). A premixed flame is one

in which the oxygen is mixed with the combustible gas by some mechanical device prior to

combustion. Figure 3-6 illustrates a laminar diffusion flame produced by a burning candle. 

(Laminar means that the flow streamlines are smooth and do not bounce around significantly.) 

Figure 3-7 illustrates practical examples of premixed flames.

Figure 3-4 Diffusion Flame

Figure 3-5 Premixed Flame

Figure 3-6 Laminar Diffusion Flame
3-11

Figure 3-7 Turbulent Premixed Flames
3-12

Most turbulent premixed flames occur in engineered combustion systems, such as a boiler, furnace,

process heater, gas burner, oxyacetylene torch, gasoline engine, or home gas cooking range. Most

natural flaming processes produce diffusion flames, since no burner or other mechanical device

exists to mix fuel and air. Common examples include a candle flame, a trash can fire,

a hydrocarbon pool fire, or a forest fire.

3.4.1 Flame Extensions Under Ceiling

Most fire protection engineering (FPE) applications are concerned with the buoyant axisymmetric

plume, which is caused by a turbulent diffusion flame above the burning fuel. When a flame

impinges on an unconfined ceiling, the unburnt gases spread out radially and entrain air for

combustion. A circular flame is then established under the ceiling, forming what is known as a

ceiling jet. The ceiling configuration is very important for at least two reasons:

(1) Fire detection devices and automatic sprinklers are generally mounted just under the

ceiling, and knowledge of the time of arrival and properties of a potential ceiling jet are

crucial for predicting when the devices will be actuated.

(2) The downward thermal radiation from a ceiling jet, and from the hot ceiling itself, is a major

factor in preheating and igniting combustible items that are not yet involved in the fire. This

radiation heat transfer is very important in affecting the rate of fire spread. Figure 3-8 shows

flame extensions under a smooth ceiling.

3.4.2 Flame Impingement

Flame that directly impacts a surface is called flame impingement. Direct flame impingement

generally transfers large quantities of heat to the surface. Flame impingement occurs when gases

from a buoyant stream rise above a localized area. The buoyant gas stream is generally turbulent

except when the fire source is very small.

3.4.3 Flame Temperature

The pulsing behavior of a flame affects its temperature. The temperature varies across the width

and height of the flame and the temperature at a fixed position will fluctuate widely, particularly

around the edges and near the top of the flame. Therefore, any discussion of flame temperature

usually involves reporting the centerline temperature or average flame temperature, which is

determined by measuring the temperature at different times and different locations within the flame.

Table 3-5 summarizes the average flame temperature for a range of common fuel types. Notice

that the flame temperature for flames involving gasoline is approximately the same as for flames

involving wood. While these values may seem odd, they are explained by the different radiation

properties of the flames produced by the respective materials.
3-13

Figure 3-8 Flame Extensions with a Free-Burning Flame

and Under a Smooth Ceiling

Table 3-5. Flame Temperatures of Selected Fuels

Fuel Source (Flames) Flame Temperature

°C (°F)

Benzene 921 (1,690)

Gasoline 1,026 (1,879)

JP-4 927 (1,701)

Kerosene 990 (1,814)

Methanol 1,200 (2,192) 

Wood 1,027 (1,881)

For convenience, we can subdivide the turbulent diffusion flames from potentially hazardous fires

into flames in the open, and room fires as described in the following sections.
Adiabatic flame temperature is defined as the flame temperature with no heat loss. 2

3-14

3.4.4 Flames Temperatures of Open Fires

The starting point for discussing the flame temperatures of open fires can be the work of the

McCaffrey (1979), who extensively studied temperatures in turbulent diffusion flames. McCaffrey

used gas burners in a “pool fire” mode (i.e., non-premixed) and studied various characteristics of

such fire plumes. He described three different regimes in such a fire plume:

(1) The continuous flame region begins slightly above the base of the fire, where the

temperatures are constant and slightly below 900 °C (1,652 °F).

(2) The intermittent flame region is above the continuous flame region. Here the temperatures

drop as a function of distance up the plume. The visible flame tips have a temperature of

about 320 °C (608 °F).

(3) The thermal plume region is beyond the flame tips, where no more flames are visible and

the temperature continues to drop as height increases away from the flame.

French researchers at the University of Poitiers recently made the same types of measurements

(Audoin et al., 1995) and reported numerical values indistinguishable from McCaffrey’s (Cox and

Chitty, 1980). The French researchers measured similar plumes and obtained very similar results

of a temperature of 900 °C (1,652 °F) in the continuous flame region, and a temperature of around

340 °C (644 °F) at the flame tips.

Taking all of the above information into account, it appears that flame tip temperatures for turbulent

diffusion flames should be estimated as being around 320 to 400 °C (608 to 752 °F). For small

flames (less than about 1 m base diameter), continuous flame region temperatures of around

900 °C (1,652 °F) should be expected. For large pools, the latter value can rise to 1,100

to 1,200 °C (2,012 to 2,192 °F).

3.4.5 Flame Temperatures in Room Fires

The fire science community generally agrees that flashover is reached when the average upper gas

temperature in the room exceeds 600 °C (1,112 °F). There will be zones with flame temperature

of 900 °C (1,652 °F), but wide spatial variations will be seen. Of interest, however, is the peak fire

temperature normally associated with room fires. This peak value is governed by ventilation and

fuel supply characteristics. As a result of these variables, peak fire temperature values will form

a wide frequency distribution (Babrauskas and Williamson, 1979). The maximum value is around

1,200 °C (2,192 °F), although a typical post-flashover room fire will more commonly have a peak

temperature of 900 to 1,000 °C (1,652 to 1,832 °F). The time-temperature curve (TTC) for the

standard fire endurance test (ASTM E119) extends to 1,260 °C (2,300 °F), as is reached in 8 hours.

Note that no jurisdiction demands fire endurance periods of more than 4 hours, at which time,

the curve only reaches 1,093 °C (1,999 °F).

The peak temperatures expected in room fires are slightly greater than those found in free-burning

open flames. Heat losses from the flame determine how far below the adiabatic flame temperature

the actual temperature will be . When a flame is far away from any walls and does not heat the 2

enclosure, it radiates to surroundings which are typically at a starting temperature of 20 °C (68 °F).

If the flame is large enough, or the room small enough, for the walls to heat up substantially, the

flame exchanges radiation with a body that is several hundred degrees Celsius; the consequence

is smaller heat losses leading to a higher flame temperature.
3-15

3.4.6 Adiabatic Flame Temperature

Adiabatic means without losing heat. Thus, adiabatic flame temperatures would be achieved in a

(theoretical) combustion system in which there are no heat losses and, hence, no radiation losses

from the flame. Because this cannot be achieved in practice (given the inefficiencies of

combustion) and is never achieved in a fire situation, adiabatic flame temperatures are calculated

values.

The amount of energy or heat released from the combustion reaction of fuel and air (or oxygen) is

the heat of combustion. If all of the energy released by this chemical reaction were used to raise

2 2 2

the temperature of the products (CO , H O, and N ) with no heat losses, the resultant temperature

would be the adiabatic flame temperature, which represents the maximum possible theoretical

temperature for a particular fuel/oxidant combustion. Table 3-6 gives adiabatic flame temperatures

for a variety of fuels. Remember from the earlier discussion, a given fuel will always have a higher

adiabatic flame temperature when burned in pure oxygen than it will when burned in normal air

(21-percent oxygen). This is because the heat of combustion must be used to raise the

temperature of the nitrogen in air and, therefore, does not contribute to the energy release.

Table 3-6. Adiabatic Flame Temperatures of Selected Fuels

Fuel Source Adiabatic Flame Temperature

K (°C) (°F)

H 2ydrogen (H ) 2,525 (2,252) (4,085)

Carbon Monoxide (CO) 2,660 (2,387) (4,329)

Methane 4(CH ) 1,446 (1,173) (2,143)

E 2 6 thane (C H ) 1,502 (1,129) (2,064)

E 2 4 thylene (C H ) 2,565 (2,289) (4,152)

A 2 2 cetylene (C H ) 2,910 (1,281) (2,338)

P 3 8 ropane (C H ) 1,554 (2,117) (3,843)

P 3 6 ropylene (C H ) 2,505 (2,232) (4,050)

n-Butane 4 10(n-C H ) 1,612 (1,339) (2,442)

n-O 8 8 ctane (n-C H ) 1,632 (1,359) (2,478)

n-Heptane 1,692 (1,419) (2,586)

n-Pentane 1,564 (1,291) (2,356)

The energy required to raise the temperature of the combustion products is determined by the mass

of the products, their heat capacities, and the difference between the initial and final temperatures.

Specific heat is defined as the amount of energy required to raise the temperature of a given

amount of product 1 °C (or K).
3-16

3.4.7 Temperatures of Objects

It is common practice for investigators to assume that an object next to a flame of a certain

temperature will also be of that same temperature. This assumption is not entirely accurate. If a

flame is exchanging heat with an object that was initially at room temperature, it will take a finite

amount of time for the temperature of that object to increase to a value similar to that of the flame.

Exactly how long this will take is a question for the study of heat transfer, which is usually presented

to engineering students over several semesters of university classes. It should be clear that simple

rules-of-thumb for first order approximations would not be expected. Here, we will merely point out

that the rate at which target objects gain heat is largely governed by their size, density, and thermal

conductivity. Small, low-density, low-conductivity objects will heat much faster than massive,

dense, highly conductive objects.

3.4.8 Flame Height Calculations

The height of a flame is a significant indicator of the hazard posed by the flame. Flame height

directly relates to flame heat transfer and the propensity of the flame to impact surrounding objects.

As a plume of hot gases rises above a flame, the temperature, velocity, and width of the plume

changes as the plume mixes with its surroundings. The size (height) and temperature of the flame

are important in estimating the ignition of adjacent combustibles. Figure 3-9 shows a characteristic

sketch of the flame height fluctuations associated with the highly intermittent pulsing structure of

a flame, particularly along its perimeter and near its top. This intermittence is driven largely by the

turbulent mixing of air and subsequent combustion, and the pulsing behavior, in turns affects the

temperature of the flame. Thus the temperature at a fixed position fluctuates widely, particularly

around the edges and near the top of the flame. This is why flame temperature is usually reported

in terms of the centerline temperature or average flame temperature.

Figure 3-9 Characteristics of Flame Height Fluctuations
3-17

Researchers define flame height as the height at which the flame is observed at least 50-percent

of the time. Above the fuel source, the flaming region is characterized by high temperature and is

generally luminous. Flames from pool fires fluctuate periodically so that the tip of the flame is

significantly different from the length of the continuous combustion (or luminous) region.

Consequently, flame height has been defined by various criteria in order to correlate data.

The flame height is an important quantitative characteristic of a fire and may affect fire detection

and suppression system design, fire heating of building structures, smoke filling rates, and fire

ventilation. Flame height typically depends on whether the flame is laminar or turbulent. In general

laminar flames are short, while turbulent flames are tall. The following two correlations are widely

used to determine the flame height of pool fires (Heskestad, 1995 and Thomas, 1962) respectively:

 (3-6)

Where:

Hf = flame height (m)

 = heat release rate of the fire (kW)

D = diameter of the fire (m)

 (3-7)

Where:

Hf = flame height (m)

D = diameter of the fire (m)

 = burning or mass loss rate per unit area per unit time (kg/m -sec) 2

a

 = ambient air density (kg/m )

3

g = gravitational acceleration (m/sec )

2

The above correlations can also be used to determine the length of the flame extension along the

ceiling and to estimate radiative heat transfer to objects in the enclosure.

The HRR of the fire can be determined by laboratory or field testing. In the absence of

experimental data, the maximum HRR for the fire is given by the following equation:

 (3-8)

Where:

 = burning or mass loss rate per unit area per unit time (kg/m -sec) 2

Hc,eff = effective heat of combustion (kJ/kg)

Af = horizontal burning area of the fuel (m )

2

k$= empirical constant (m )

-1

D = diameter of burning area (m)
3-18

For non-circular pools, the effective diameter is defined as the diameter of a circular pool with an

area equal to the actual pool area given by the following equation:

 (3-9)

Where:

Af is the surface area of the non-circular pool

3.5 Assumptions and Limitations

The methods discussed in this chapter are subject to several assumptions and limitations that apply

to HRR:

(1) The pool fire is burning in the open and is characterized by instantaneous, complete

involvement of the flammable/combustible liquid.

(2) There is no fire growth period. (Real liquid pool fires grow very quickly, and it is realistic to

assume that the pool fire instantaneously reaches its maximum HRR.)

In addition, the following assumptions and limitations apply to burning duration:

(1) The pool is circular or nearly circular and contains a fixed mass or volume of

flammable/combustible liquid. The mass or volume of any spill with a non-circular

circumference must be approximated as a circular measurement. For example an

accidental fuel is ignited in a pump room and causes cable trays to be exposed to a pool

fire. The spill area is a rectangular dike with dimensions of 4-ft x 5-ft. The equivalent

diameter of the pool fire is given by Equation 3-9:

 

Where:

Af = the surface area of noncircular pool

Therefore, the equivalent diameter of the non-circular pool is as follows:

(2) There is no fire growth period. (As stated above, real liquid pool fires grow very quickly, and

it is realistic to assume that the pool fire instantaneously reaches its maximum HRR.)
3-19

In addition, the following assumptions and limitations apply to flame height:

(1) The flame height correlation described in this chapter was developed for horizontal pool fire

sources in the center or away from the center of the compartment. The turbulent diffusion

flames produced by fires burning near or close to a wall or in a corner configuration of a

compartment effect the spread of the fire. The flame height correlations of fires burning

near walls and corners is presented in Chapter 4.

(2) The size of the fire (flame height) depends on the diameter of the fuel and the HRR

attributable to the combustion.

(3) This correlation is developed for two-dimensional sources (primarily pool fires) and this

method assumes that the pool is circular or nearly circular.

(4) There is no fire growth period. (As stated above, real liquid pool fires grow very quickly, and

it is realistic to assume that the pool fire instantaneously reaches its maximum HRR.)

3.6 Required Input for Spreadsheet Calculations

The user must obtain the following values before attempting a calculation using the characteristics

of liquid pool fire spreadsheet:

(1) fuel spill volume (gallons)

(2) fuel spill area or dike area (ft )

2

(3) fuel type

3.7 Cautions

(1) Use (03_HRR_Flame_Height_Burning_Duration_Calculation.xls) spreadsheet on the CD-ROM.

(2) Make sure to enter the input parameters in the correct units.

3.8 Summary

An engineering approach to pool fire burning characterization requires a classification according

to the dominant heat transfer mechanism, which can be expressed as being dependent on pool

diameter. The pool shall include fires resulting from spilled liquids, fires in diked or curbed areas,

and fires in open areas. These fires will be typically considered to be circular.

Estimating the burning duration of a pool fire involves the following steps:

(1) Determine the regression rate of the pool fire.

(2) Calculate the equivalent diameter of the pool fire.

(3) Calculate the burning duration of the pool fire.

The flame height is generally defined as the height at which (or above which) the flame is observed

at least 50-percent of the time. Visual observations tend to yield slight overestimations of flame

height.
3-20

Estimating the flame height from a pool fire involves the following steps:

(1) Determine the HRR of the pool fire.

(2) Calculate the equivalent diameter of the pool fire.

(3) Determine the height of the pool fire flame.

3.9 References

ASTM E1354-97, “Standard Test Method for Heat and Visible Smoke Release Rates for Materials

and Products Using an Oxygen Consumption Calorimeter,” ASTM Fire Test Standard, Fifth Edition,

American Society of Testing and Materials, West Conshohocken, Pennsylvania, pp. 1097–1114,

1999.

Audoin, L., et al., “Average Centerline Temperatures of a Buoyant Pool Fire Obtained by Image

Processing of Video Recordings,” Fire Safety Journal, Volume 24, pp. 107–130, 1995.

Babrauskas, V., et al., “Fire Performance of Wire and Cable: ReactionntonFire Tests A Critical

Review of the Existing Methods of New Concepts,” NIST Technical Note 1291, U.S. Department

of Commerce, National Institute of Standards and Technology (NIST), Building and Fire Research

Laboratory (BFRL), Gaithersburg, Maryland, 1991.

Babrauskas, V. “Estimating Large Pool Fire Burning Rates,” Fire Technology, November,

pp. 251–261, 1983.

Babrauskas, V., “Free-Burning Fires,” Fire Safety Journal, Volume, 11, Nos. 1 & 2, pp. 33–51,

July/September 1986.

Babrauskas, V., “Burning Rates,” Section 3, Chapter 3-1, SFPE Handbook of Fire Protection

Engineering, 3 Edition, P.J. DiNenno, Editor-in-Chief, National Fire Protection Association, Quincy, rd

Massachusetts, 2002.

Babrauskas, V., and R.B. Williamson, “Post-Flashover Compartment Fires,” Fire and Materials,

Volume 2, pp. 39–53: 1978, and Volume 3, pp. 1–7, 1979.

Chavez, J.M., “An Experimental Investigation of Internally Ignited Fires in Nuclear Power Plant

Control Cabinets: Part 1 Cabinet Effects Tests,” NUREG/CR-4527, U.S. Nuclear Regulatory

Commission, Washington, DC, April 1987.

Cox, G., and R. Chitty, “A Study of the Deterministic Properties of Unbounded Fire Plumes,”

Combustion and Flame, Volume 39, pp. 191–209, 1980.

Heskestad, G., “Fire Plumes,” Section 2, Chapter 2-2, SFPE Handbook of Fire Protection

Engineering, 2 Edition, P.J. DiNenno, Editor-in-Chief, National Fire Protection Association, nd

Quincy, Massachusetts, 1995.

Karlsson, B., and J.G. Quintiere, Chapter 3, “Energy Release Rates,” Enclosure Fire Dynamics.

CRC Press LLC, New York, pp. 25–46, 1999.
3-21

Lee, B.T., “Heat Release Rate Characteristics of Some Combustibles Fuel Sources in Nuclear

Power Plants,” NBSIR 85-3195, U.S. Department of Commerce, National Bureau of Standards

(NBS), Washington, DC, July 1985.

McCaffrey, B.J., “Purely Buoyant Diffusion Flames: Some Experimental Results,” NBSIR 79n1910,

National Bureau of Standards (NBS), Washington, DC, 1979.

Nowlen, S.P., “Heat and Mass Release for Some Transient Fuel Sources Fires: A Test Report,”

NUREG/CR-4680, U.S. Nuclear Regulatory Commission, Washington, DC, October 1986.

Nowlen, S.P., “Quantitative Data on the Fire Behavior of Combustible Materials Found in Nuclear

Power Plants: A Literature Review,” NUREG/CR-4679, U.S. Nuclear Regulatory Commission,

Washington, DC, February 1987.

Thomas, P.H., “The Size of Flames from Natural Fires,” Nine Symposium (International) on

Combustion, The Combustion Institute, Pittsburgh, Pennsylvania, pp. 844–859, 1962.

3.10 Additional Readings

Davenport, J.A., and R.P. Benedetti, Editors, Understanding Fire Protection for Flammable Liquids,

National Fire Protection Association, Quincy, Massachusetts, 2003.

Heskestad, G., “Flame Heights of Fuel Arrays with Combustion in Depth,” Proceedings of the Fifth

International Symposium on Fire Safety Science, International Association of Fire Safety Science,

pp. 427–438, 1997.

Ingason, H., “Two Dimensional Rack Storage Fires,” Proceedings of the Fourth International

Symposium on Fire Safety Science, International Association of Fire Safety Science,

pp. 1209–1220, 1994.

Ingason, H., and J. de Ris, “Flame Heat Transfer in Storage Geometries,” Fire Safety Journal, 1997.

McCaffrey, B.J., “Flame Height,” Section 2, Chapter 2-1, SFPE Handbook of Fire Protection

Engineering, 2 Edition, P.J. DiNenno, Editor-in-Chief, National Fire Protection Association, nd

Quincy, Massachusetts, 1995.

Mudan, K.S., and P.A. Croce, “Fire Hazard Calculations for Large Open Hydrogen Fires,” Section

3, Chapter 3-11, SFPE Handbook of Fire Protection Engineering, 2 Edition, P.J. DiNenno, Editor- nd

in-Chief, National Fire Protection Association, Quincy, Massachusetts, 1995.

Smith, D.A., and G. Cox, “Major Chemical Species in Turbulent Diffusion Flames,” Combustion and

Flame, Volume 91, pp. 226–238, 1992.

Yuan, L.M., and G. Cox, “An Experimental Study of Some Line Fires,” Fire Safety Journal, Volume

27, pp. 123–139, 1997.
3-22

Example Problem 3-1: Compartment with Pool Fire

3.11 Problems

Example Problem 3.10-1

Problem Statement

A pool fire scenario arises from a breach (leak or rupture) in an auxiliary cooling water pump oil

tank. This event allows the fuel contents of the pump to spill and spread over the compartment

floor. A 5-gallon, 9.0-ft surface area spill of flammable liquid (lubricating oil) leads to consideration 2

of a pool fire in a compartment with a concrete floor. The fuel is ignited and spreads rapidly over

the surface, reaching steady burning almost instantly. Compute the HRR, burning duration, and

flame height of the pool fire. The dimensions of the compartment are 15 ft wide x 15 ft deep x 10

ft heigh. The cable tray is located 8 ft above the pool fire. Determine whether the flame will

impinge upon the cable tray. Assume instantaneous and complete involvement of the liquid pool

with no fire growth and no intervention by the plant fire department or automatic suppression

systems.

Solution

Purpose:

(1) Determine the Heat Release Rate (HRR) of the fire source.

(2) Determine the burning duration of the pool fire.

(3) Determine the flame height of the pool fire.

(4) Determine whether the flame will impinge upon the cable tray.

Assumptions:

(1) Instantaneous and complete involvement of the liquid in the pool fire

(2) The pool fire is burning in the open

max (3) No fire growth period (instantaneous HRR )

(4) The pool is circular or nearly circular and contains a fixed mass of liquid volume

(5) The fire is located at the center of the compartment or away from the walls
3-23

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 03_HRR_Flame_Height_Burning_Duration_Calculations.xls

FDT Input Parameter: s

-Fuel Spill Volume (V) = 5 gallons

dike -Fuel Spill Area or Dike Area (A ) = 9.0 ft2

-Select Fuel Type: Lube Oil

Results*

Heat Release Rate

(HRR)

 kW (Btu/sec)

Burning

Du bration (t )

(min.)

Poo fl Fire Flame Height (H )

m (ft)

Method of

Heskestad

Method of

Thomas

772 (731) 7.35 2.31 (7.6) 2.67 (8.75) 

 *see spreadsheet on next page

Both methods for pool fire flame height estimation show that pool fire flame will impinge upon

the cable tray.
3-24

Spreadsheet Calculations

FDT : 03_HRR_Flame_Height_Burning_Duration_Calculations.xls (HRR-Calculations) s

CHAPIER 1 ESllMATtiG BlRING CHARAClERISllCS Of UQUD POOL FII'E, 

I£ AT ~'!:LEASE RAlE, BffiNNG llffiAllON, Al'l> FI..MI: I£1GHT 

V..oo>1805.0 lhetib.l.irg~o.tmcnse:slilae1hehra~e:aserze,turirgdr.l):n,a'd1aret'Qtttrlqj:lp:dft. 

~inYEI.LOWCELlSn ~bvlhellsa'. 

~inGF'E~Ca.LSnA.JcrtmccllySe!ede:lfrantte CRCP ~ M~Ufa1te R..JE1 Se!a:ted 

Jl9.bse:prt«*U\9Jes<nc3::UZ>:dbylhe~3'dba9:!dcnv.iles~Riin1heirp.t 

~ Ths~is~3'dSECJSet031.00Efltf'Sd.Je10au.«rgEI1ryilaoe!~). 

lhe~in1te NLIRlsh:d:lberE:adbetreala"lty3sisr1"1300. 

ltf'UT PARMEIERS 

fUel 51>11 \OUTel)/) 500 g~ :u 

fUel 51>11,.,.-!h,.,(A..,) 900 ( 

,_a.r;rg RleofRJell!rl) 0009 g111 ;ec 

~ 1-tSofO:nb.dicnof!U::I (laH ) 4lm) •;.ug 

fUel !lmv(p) 78) I gill 

- Olroat(Wl) m 

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ll<Maia-S.Po::6a:Ul(g) 9.81 '"'~"~ 

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ItO>: A-~l...,.,.;;alyan<lwlh-ArTEfTJl03Ue(T.) ..,.. 

TIE-_ PROPIRTIESDATA 

EU<NI~ R!lTE CAll\ FOR LIGIJD Hl'CRXA!alN R£l.S 

fUel Mosi!JTrgRie 1-19 of Cl:ntu;licn 

nl'(l¢(=) "Hu ii<Jkg) 

M!ltad 0017 lDJW 

Bhml 0015 l6,Ql) 

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--- 0.101 44.{(1) 

X)lole 009 4l,Ql) 

-., 0041 25,Ql) 

0003le OOil l6;l00 

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a..r. 0041 44,700 

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0<0!1 004) 44,430 

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" 

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791 

194 

513 

874 

600 

675 

870 

791 

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714 

74) 

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810 

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810 

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100 S::rclll<> d!siredtu!ltp 

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2.7 

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3B 

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35 

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3-25

ESTIMATING POOL FIRE HEAT RELEASE RATE 

P,e 'I! IUO? : S ,=p E ,"'{;?,;(b;:..W, ot ,={,* P:o ~t~ t E:gllnvt,:g , :f' Ed l b •, 2002, P~~ J-25. 

Q = m''iLH ~.t (1 · e ""0

) At...., 

Where Q =pool fire heat release rate (kW) 

nt' =mass buminQ raM of fuel per unitsurface area (kWm2-sec) 

lLH ~ .. ·= effective heat of combustion of fuel (kJA<g) 

A= ~o.c =surface area of pool fire (area involved in vaporization) (m2

) 

kP =empirical constant (m ·) 

D =diameter of pool1ire(diameter involved in vaporization, circular pool is assumed)(m) 

Pod Fire Diameter Calc:ulal:ion 

~~.. = 71[)"/4 

Where At...., = surface area of pool fire (m2

) 

D =pool fire diam~r (m) 

D = >( 4A,.,I><) 

D = 1.032 m 

ESTIMATING POOL FIRE BURNING DURATION 

t:.=4V/7C/ v 

Where tc. =burning duration of pool fire (sec) 

V=volume of liquid(m:~) 

D =pool diameter (m) 

v = reQression rate (nv'sec) 

CalcUction for Ret=~ression Rate 

v = rrt'lp 

Where v = reQression rate (nv'sec) 

nt'- mass burninQ rate of fuel (lq:r'm2-sec) 

p =liquid fuel densitv(lq:r'm:t) 

v = 0.000l51 nv'sec 

BurninA Duration CalcUction 

=4V.mD ' v 

tto' Qat a 1t1••:1 pootn~ wta a giJu a .. -.outonutcaa bm tor gp~ rb t; otOM ~r"natl al!a r Dr 

rtp~rb t; tOM ~ral.u;t: a1M. 

ESTIMA liNG POOL FIRE FLAME HEIGHT 

lvETHOD OF HESKESTAD P,~'I:IUO: : =PE.'·f .i<b~;.W. T.:i.* Olo;t~'\~ S:g ll l'iig .'f" E<IIIIU, 19i't5, Pag: 2-10. 

H, = 0.235 rt• · 1.02 D 

Where Ho = pool fire flame height (m) 

Q =pool fire heat release rate (kW) 

D =pool fire diameter (m) 

Pod Fire Flame HeiQ-4 Calculation 

=0.235 rio· 1.02 D 
3-26

METHOD OF THOMAS 

Pi~ 't<NU: s;::p=~-..:J..('( «fbn 'n;J. "" &IIICf\ I~ P~ ~ZOO. 

H, • poolm Thill ~ h.;JU (II) 

m• • Ill aa IU Qllg "'' OT1U lp? I I I lH ltiO: <ma ;J glhl ¢) 

p,.• <llllb'"ltallm ult'{ ;J;g.hl) 

0 • p001111e II.'IIIH~ I II) 

g - grwlti1JHa cc~l? rau,. ~~ ~ 

Pool Fi r~ Flam$ Helgllt0llcula11on 

H,• 1.2 o Qll"l p,.v@ D))'"' 

!H,= 7 m 

Flame, HtHoht Calcul:~t.on · Summanrof Results 

C iliCUh'IUOO f.1 &1hOd 

r.1ETHOD OF HESKESTAD 

r.1 ETHOD OF THO MAS 

3.7 5 1t 11 '441'4' 

ESTIMATING POOL FIRE RESULTS FOR RAND OM SIZE SPILLS USING INPUT PARAMETERS 

~:. (m 1

) let ••• r Q 1kVv1 

I 0.03 o.u 85.72 $370. 11 

' 0.13 0.43 17 1.45 1335.05 

' (1.2$ ~0 257.17 1$2$.$7 

" 0.$7 ~3 uuo 332.5$ 

' us 0.77 J2U 2 nu+2 

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3-27

Example Problem 3-2: Compartment with Pool Fire

Example Problem 3.10-2

Problem Statement

A standby diesel generator (SBDG) room in a power plant has a 3-gallon spill of diesel fuel over a

1-ft diked area. This event allows the diesel fuel to form a pool. The diesel is ignited and fire 2

spreads rapidly over the surface, reaching steady burning almost instantly. Compute the HRR,

burning duration, and flame height of the pool fire. The dimensions of the compartment are 10 ft

wide x 12 ft deep x 12 ft high. The cable tray is located 10 ft above the pool fire. Determine

whether flame will impinge upon the cable tray. Also, determine the minimum area required of the

pool fire for the flame to impinge upon the cable tray. Assume instantaneous, complete

involvement of the liquid pool with no fire growth and no intervention by plant fire department or

automatic suppression.

Solution

Purpose:

(1) Determine the Heat Release Rate (HRR) of the fire source.

(2) Determine the burning duration of the pool fire.

(3) Determine the flame height of the pool fire.

(4) Determine whether the flame will impinge upon the cable tray.

(5) Determine the minimum dike area required for the flame to impinge upon the cable tray.

Assumptions:

(1) Instantaneous and complete involvement of the liquid in the pool fire

(2) The pool fire is burning in the open

max (3) No fire growth period (instantaneous HRR )

(4) The pool is circular or nearly circular and contains a fixed mass of liquid volume

(5) The fire is located at the center of the compartment or away from the walls
3-28

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 03_HRR_Flame_Height_Burning_Duration_Calculations.xls

FDTs Input Parameter:

-Fuel Spill Volume (V) = 3 gallons

dike -Fuel Spill Area or Dike Area (A ) = 1.0 ft2

-Select Fuel Type: Diesel

Results*

Heat Release Rate

(HRR)

kW (Btu/sec)

Burning

Du bration (t )

(min.)

Poo fl Fire Flame Height (H )

m (ft)

Method of

Heskestad

Method of

Thomas

95 (90) 42 1.1 (3.6) 1.4 (4.5)

*see spreadsheet on next page

Both methods for pool fire flame height estimation show that pool fire flame will not impinge the

cable tray.

To determine the minimum dike area required for the flame to impinge upon the cable tray, the

user must substitute different values for the area in the spreadsheet until we obtain a flame

height value of 10 ft (cable tray height). The user must keep the input values used for the

previous results, and change only the area value. This trial and error procedure is shown in the

following table.

Tr dike ial A

(ft )

2

Poo fl Fire Flame Height (H )

m (ft)

Method of Heskestad Method of Thomas

1 9 2.4 (8.0) 2.9 (9.6)

2 10 2.6 (8.4) 3.0 (9.9)

3 11 2.6 (8.6) 3.1 (10.2)

To be conservative, we are going to consider the method that gets first the 10-ft flame height.

The method of Heskestad tells that the pool fire flame will impinge upon the cable tray if the dike

area is 6.1 ft . For practical purposes, we could say that a spill pool area around 5–6 ft would 2 2

be a risk for the cable tray integrity.
3-29

Spreadsheet Calculations

FDT : 03_HRR_Flame_Height_Burning_Duration_Calculations.xls (HRR-Calculations) s

CHAPTER 3. ESTIMATING BURNING CHARACTERISTICS OF LIQUID POOL FIRE, 

HEAT RELEASE RATE, BURNING DURATION, AND FLAME HEIGHT 

Versicn 1805.0 11~ 1:11nlrt.~ eolcU~t 1 ~ to~~k •~ ~~~lldNoa ~~~ ,I>Ut11W .t.t~l ~._I1~M I~Will 1:1 I<J\tl J>OCI•'. 

p,.-,,m,\w(.lll veuowceue ,,r, Bl\lrt4 1> 1 ' '' u ~r. 

p,.-llmt\lr(.lll ORESI C B le .ut Joi~ MtOillly etlt0\14 1'\lm 11" OROP OO'AII !.lSI II 1:>r11•t Flltl etl~-4. 

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1h~ d~~11n h • II.B:> .A ll>t•ft~ll> 1:rt ~~fl m~lt. 

INPUT PARAMETERS 

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3-30

ESTIMATING POOL FIRE HEAT RELEASE RATE 

P,Ui 1~ •o: : S ,=p E .'·f~.;cbc..W. ot ,={,* P:o lo;t ~ e.g t. tr,g , :j"' 6:1 lb •, 2002, P~~ J-25. 

Q = m"lLH ~.,, (1 • e ""0

) At...., 

Where Q =pool fire heat release rate (kW) 

nt' =mass buminQ raW of fuel per unit surface area (kWm2-sec) 

lLH ~.,, = effective heat of combustion of fuel (kJA<g) 

A= ~o. .. =surface area of pool fire (area involved in vaporization) (m2

) 

kP =empirical constant (m ·) 

D =diameter of pool1ire (diameter involved in vaporization, circular pool is assumed) (m) 

Pod Fire OiamSer Calc:ulal:ion 

~~o.. = 71()"/4 

Where At...., = surface area of pool fire (m2

) 

D =pool fire diamtl>!r (m) 

D = v( 4A. ~o../79 

D = 0.344 m 

ESTIMA liNG POOL FIRE BURNING DURATION 

(U:IH:I> Wlli tel.1t11W . tU 'll.'l>. pollt, II ~ 1J<m1HIIUOII, 1~ l'lle 

t•~a bd 

t:.=4V/7C/ v 

Where t:. =burning duration of pool fire (sec) 

V=volume of liquid(m' ) 

D =pool diameter (m) 

v = reQression rate (nv'sec) 

CalcUction for Ret=~ression Rate 

v = rrt'lp 

Where v = reQression rate (nv'sec) 

rrt'- mass burninQ rate of fuel (lq:r'm2-sec) 

P =liquid fuel densitv(lq:r'm:t) 

v = 0.000049 nv'sec 

BurninA Duration CalcUction 

=4V.mD ' v 

ESTIMA liNG POOL FIRE FLAME HEIGHT 

lvETHOD OF HESKESTAD 

P,e'IHUO: : =PE.'·f~.i<b~;.W. oT.:i.* P:Ulo;t~'\~ S:g ll l'iig .':!" E<IIIIU, 19i't5, Pag: 2-10. 

,. Ho=D.235 Q · 1.02 D 

Where H, = pool fire flame height (m) 

Q =pool fire heat release rate (kW) 

D =pool fire diameter (m) 

Pod Fire Flame HeiQ-4 Calculation 

H1 = 0.235 r:fo • 1.02 D 
3-31

METHOD OF THOMAS 

Pi~ 't<NU: s;::p=~-..:J..('( «fbn 'n;J. "" &IIICf\ I~ P~ ~ZOO. 

H, • poolm Thill ~ h.;JU (II) 

m• • Ill aa IU Qllg "'' OT1U lp? I I I lH ltiO: <ma ;J glhl ¢) 

p,.• <llllb'"ltallm ult'{ ;J;g.hl) 

0 • p001111e II.'IIIH~ I II) 

g - grwlti1JHa cc~l? rau,. ~~ ~ 

Pool Fi r~ Flam$ Helgllt0llcula11on 

H,• 1.2 o Qll"l p,.v@ D))'"' 

!H,= u~ m 

Flame, HtHoht Calcul:~t.on · Summanrof Results 

C iliCUh'IUOO f.1 &1hOd 

r.1ETHOD OF HESKESTAD 

r.1 ETHOD OF THOMAS 

U 2 

us 

us 1t 11 '441'4' 

ESTIMATING POOL FIRE RESULTS FOR RAND OM SIZE SPILLS USING INPUT PARAMETERS 

~:. (m 1

) let ••• r Q 1kVv1 

I 0.03 o.u 35.47 243US 

' 0.13 0.43 U0.35 IUU2 

' (1.2$ ~0 28S.J2 $$1.22 

" 0.$7 ~3 $$1.$3 .4 1 

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3-32

Example 3-3: Compartment with Pool Fire

Example Problem 3.10-3

Problem Statement

In one NPP, it was important to determine whether a fire involving a 4-gallon spill of lubricating oil

from an auxiliary feedwater (AFW) pump could cause damage to an unprotected electrical cable

pull box and cable trays. The unprotected pull box and cable trays were located 10 ft and 8 ft above

the AFW pump, respectively. The pump room had a floor area of 20 ft x 20 ft and a ceiling height

of 15 ft with a vent opening of 5 ft x 15 ft. Compute the HRR, burning duration, and flame height of

the pool fire with a diameter of 4 ft. The lowest cable tray is located 8 ft above the pool. Determine

whether flame will impinge upon the cable tray or cable pull box. Assume instantaneous, complete

involvement of the liquid pool with no fire growth and no intervention by the plant fire department

or automatic suppression systems.

Solution

Purpose:

(1) Determine the Heat Release Rate (HRR) of the fire source.

(2) Determine the burning duration of the pool fire.

(3) Determine the flame height of the pool fire.

(4) Determine whether the flame will impinge upon the cable tray or cable pull box.

Assumptions:

(1) Instantaneous and complete involvement of the liquid in the pool fire

(2) The pool fire is burning in the open

max (3) No fire growth period (instantaneous HRR )

(4) The pool is circular or nearly circular and contains a fixed mass of liquid volume

(5) The fire is located at the center of the compartment or away from the walls
3-33

Pre FDT Calculations: s

The input parameters of the FDT assigned for this problem are the fuel spill volume, dike area s

and fuel material. As we can see, the problem statement does not give the dike area but the

pool diameter is given. The dike area can be obtained from the formula of the area of a circle,

since we assume that the pool has circular shape.

Spreadsheet (F DT )

s

Information:

Use the following FDT :

s

(a) 03_HRR_Flame_Height_Burning_Duration_Calculations.xls

FDT Inputs: (for both spreadsheets) s

-Fuel Spill Volume (V) = 4 gallons

dike -Fuel Spill Area or Dike Area (A ) = 12.56 ft2

-Select Fuel Type: Lube Oil

Results*

Heat Release Rate

(HRR)

kW (Btu/sec)

Burning

Du bration (t )

(min.)

Poo fl Fire Flame Height (H )

m (ft)

Method of

Heskestad

Method of

Thomas

1,202 (1,139) 4.2 2.8 (9.1) 3.0 (9.8)

 *see spreadsheet on next page

Both methods for pool fire flame height estimation show that pool fire flame will impinge upon the

cable tray and cable pull box.
3-34

Spreadsheet Calculations

FDT : 03_HRR_Flame_Height_Burning_Duration_Calculations.xls (HRR-Calculations) s

CHAPTER 3. ESTIMATING BURNING CHARACTERISTICS OF LIQUID POOL FIRE, 

HEAT RELEASE RATE, BURNING DURATION, AND FLAME HEIGHT 

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3-35

ESTIMATING POOL FIRE HEAT RELEASE RATE 

P,Ui 1~ •o: : S ,=p E .'·f~.;cbc..W. ot ,={,* P:o lo;t ~ e.g t. tr,g , :j"' 6:1 lb •, 2002, P~~ J-25. 

Q = m"lLH ~.,, (1 • e ""0

) At...., 

Where Q =pool fire heat release rate (kW) 

nt' =mass buminQ raW of fuel per unit surface area (kWm2-sec) 

lLH ~.,, = effective heat of combustion of fuel (kJA<g) 

A= ~o. .. =surface area of pool fire (area involved in vaporization) (m2

) 

kP =empirical constant (m ·) 

D =diameter of pool1ire (diameter involved in vaporization, circular pool is assumed) (m) 

Pod Fire OiamSer Calc:ulal:ion 

~~o.. = 71()"/4 

Where At...., = surface area of pool fire (m2

) 

D =pool fire diamtl>!r (m) 

D = v( 4A. ~o../79 

D = 1.219 m 

ESTIMA liNG POOL FIRE BURNING DURATION 

(U:IH:I> Wlli tel.1t11W . tU 'll.'l>. pollt, II ~ 1J<m1HIIUOII, 1~ l'lle 

t•~a bd 

t:.=4V/7C/ v 

Where t:. =burning duration of pool fire (sec) 

V=volume of liquid(m' ) 

D =pool diameter (m) 

v = reQression rate (nv'sec) 

CalcUction for Ret=~ression Rate 

v = rrt'lp 

Where v = reQression rate (nv'sec) 

rrt'- mass burninQ rate of fuel (lq:r'm2-sec) 

P =liquid fuel densitv(lq:r'm:t) 

v = 0.000l51 nv'sec 

BurninA Duration CalcUction 

=4V.mD ' v 

ESTIMA liNG POOL FIRE FLAME HEIGHT 

lvETHOD OF HESKESTAD 

P,e'IHUO: : =PE.'·f~.i<b~;.W. oT.:i.* P:Ulo;t~'\~ S:g ll l'iig .':!" E<IIIIU, 19i't5, Pag: 2-10. 

,. Ho=D.235 Q · 1.02 D 

Where H, = pool fire flame height (m) 

Q =pool fire heat release rate (kW) 

D =pool fire diameter (m) 

Pod Fire Flame HeiQ-4 Calculation 

H1 = 0.235 r:fo • 1.02 D 
3-36

METHOD OF THOMAS 

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H,• 1.2 o Qll"l p,.v@ D))'"' 

!H,= ~3 m 

Flame, HtHoht Calcul:~t.on · Summanrof Results 

C iliCUh'IUOO f.1 &1hOd 

r.1ETHOD OF HESKESTAD 

r.1 ETHOD OF THOMAS 

3.32 It 11 '441'4' 

ESTIMATING POOL FIRE RESULTS FOR RAND OM SIZE SPILLS USING INPUT PARAMETERS 

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4-1

CHAPTER 4. ESTIMATING WALL FIRE FLAME HEIGHT,

LINE FIRE FLAME HEIGHT AGAINST THE WALL,

AND CORNER FIRE FLAME HEIGHT

4.1 Objectives

This chapter has the following objectives:

• Identify the three regions of a diffusion flame.

• Explain how corners and walls affect flames.

• Define relevant terms, including persistent flame region, intermittent flame region,

flame height, and flame extension.

4.2 Introduction

If a fire is located close to a wall or a corner (i.e., formed by the intersection of two walls),

the resulting restriction on free air entrainment will have a significant effect on fire growth

and spread. The primary impact of walls and corners is to reduce the amount of entrained air

available to the flame or plume. This lengthens flames and causes the temperature in a plume to

be higher at a given elevation than it would be in the open. Remember that the expression

for estimating flame height given in Chapter 3 assumes that the fire source is located away from

the walls and corners.

When a diffusion flame develops and is in contact with the wall, its structure can be subdivided into

three regions, which are commonly identified as the persistent flame region, the intermittent flame

region, and the buoyant plume region. As the plume rises to the ceiling, its direction changes from

vertical (upward) to horizontal. Until the point where the flow changes direction, the plume

is primarily driven by buoyancy. Thereafter, the plume is driven by its residual momentum

and becomes a jet, which is referred to as the “ceiling jet.”

The flame heats the wall material with which it comes in contact. The heat flux to the wall is

a function of location and is highest in the persistent flame region. The flame height depends on

the amount of air entrained which, in turn, is proportional to the fuel heat release rate.

On occasions, it may also be necessary to calculate the flame projections against a wall

from the spill of flammable liquid in a trench or flames emerging from a burning electrical cabinet.

4.3 Flame Height Correlations for Walls Fires, Line Fires, and Corner Fires

In a wall flame, the wall-side heat flux appears to be governed by the flame radiation, while the heat

flux in the far field is primarily attributable to convection. This implies that flame height can be a

scaling factor representing the distribution of wall heat transfer. Using the analogy of unconfined

fires, the flame height is expected to depend only on the gross heat release rate of the fuel.

The terms “flame height” and “flame extension” designate the lengths of flame in the vertical and

horizontal directions, respectively. A wall flame generated from a fire located against a wall can

only entrain air from half of its perimeter. Thus, wall flame can be considered to be geometrically

half of an axisymmetric flame and its mass flow rate, in turn, is half of that from an axisymmetric

flame.
4-2

A flame generated from a fire located in a corner of a compartment (typically where the intersecting

walls form a 90° angle) is referred to as corner flame. Corner fires are more severe than wall fires

because of the radiative heat exchange between the two burning walls. However, the physical

phenomena controlling fire growth in corner and wall scenarios are very similar, if not identical.

4.3.1 Wall Fire Flame Height Correlation

Delichatsios (1984) reported by Budnick, Evans, and Nelson (1997) developed a simple correlation

of flame height for elongated fire based on experimental data. Figure 4-1 depicts the configuration

used in developing the correlation for wall flame height. In the following correlation, the flame

height is based on the rate of HRR per unit length of the fire:

 (4-1)

Where:

Hf(Wall) = wall flame height (m)

0.034 = entrainment coefficient

= HRR per unit length of the fire (kW/m)

The above correlation can be used to determine the length of the flame against the wall and to

estimate radiative heat transfer to objects in the enclosure.

4.3.2 Line Fire Flame Height Correlation

Delichatsios (1984) reported by Budnick et. al., (1997) also developed a flame height correlation

for line fires against a wall. Like the wall fire flame height correlation, this correlation is based on

experimental data. The geometry for this case is shown in Figure 4-2. Delichatsios’ correlation is

expressed by the following equation based on the rate of HRR per unit length of the fire:

 (4-2)

Where:

Hf(Wall, Line) = line fire flame height (m)

0.017 = entrainment coefficient

= HRR per unit length of the fire (kW/m)

The above correlation can be used to determine the length of the flame against the wall from a

line fire source and can be used to estimate radiative heat transfer to objects in the enclosure.
4-3

Figure 4-1 Wall Fire Flame Configuration

Figure 4-2 Line Fire Flame Against a Wall
4-4

4.3.3 Corner Fire Flame Height Correlation

A corner fire may be modeled using a pool fire and specifying the center coordinates as the apex

of the corner. At the start of the fire, a diffusion flame develops and makes contact with the walls.

As flames spread along the intersection of wall and ceiling, they eventually reach another corner.

With a noncombustible ceiling, flames also spread downward. By contrast, with a combustible wall,

the heat transfer between two walls in contact with the fire source results in a much more rapid fire

spread. Figure 4-3 depicts the configuration used in developing the corner flame height correlation

from experimental data. Hasemi and Tokunaga (1983 and 1984) suggest the following expression,

based on the correlation of an extensive number of fire tests:

 (4-3)

Where:

Hf(Corner) = corner fire flame height (m)

0.075 = entrainment coefficient

= HRR of the fire (kW)

The above correlation can be used to determine the length of the flame against the intersection of

two walls and to estimate radiative heat transfer to objects in the enclosure.

Figure 4-3 Corner Fire Flame Configuration
4-5

4.4 Assumptions and Limitations

The methods discussed in this chapter are subject to several assumptions and limitations:

(1) This method includes correlations for flame height for liquid fire.

(2) The size of the fire (flame height) depends on the length of the fire.

(3) This correlation is developed for two-dimensional sources.The turbulent diffusion flames

produced by fires burning at or near a wall configuration of a compartment affect the

spread of the fire.

(4) Air is entrained only from one side during the combustion process.

4.5 Required Input for Spreadsheet Calculations

The user must obtain the following information to use the spreadsheet:

(1) fuel type (material)

(2) fuel spill volume (gallons)

(3) fuel spill area (ft )

2

4.6 Cautions

(1) Use the appropriate spreadsheet (04_Flame_Height_Calculations.xls) on the CD-ROM

for wall fire flame height, line fire flame height, and corner fire flame height calculations.

(2) Use the page that best represents the fire configuration.

(3) Make sure to enter the input parameters in the correct units.

4.7 Summary

This chapter describes methods of calculating the height of a flame and its buoyant gases when

the fire source is near a wall or a corner. These fire scenarios are often used as idealized

representatives of situations of much greater complexity. The correlations presented were obtained

from laboratory scale fires providing local measurements of gas temperature and velocity both

below and above the flame tips, as well as measurements of visual flame length.
4-6

4.8 References

Budnick, E.K., D.D. Evans, and H.E. Nelson, “Simple Fire Growth Calculations,” Section 11 Chapter

10, NFPA Fire Protection Handbook, 18 Edition, National Fire Protection Association, Quincy, th

Massachusetts, 1997.

Delichatsios, M.A., “Flame Heights of Turbulent Wall Fire with Significant Flame Radiation,”

Combustion Science and Technology, Volume 39, pp. 195–214, 1984.

Hasemi Y., and T.Tokunaga, “Modeling of Turbulent Diffusion Flames and Fire Plumes for the

Analysis of Fire Growth,” Proceedings of the 21 National Heat Transfer Conference, American st

Society of Mechanical Engineers (ASME), 1983.

Hasemi Y., and T.Tokunaga, “Some Experimental Aspects of Turbulent Diffusion Flames and

Buoyant Plumes from Fire Sources Against a Wall and in Corner of Walls,” Combustion Science

and Technology, Volume 40, pp. 1–17, 1984.
4-7

4.9 Problems

Example Problem 4.9-1

Problem Statement

A pool fire scenario arises from a breach (leak or rupture) in an oil-filled transformer. This event

allows the fuel contents of the transformer to spill 2 gallons along a wall with an area of 9 ft .

2

A cable tray is located 8 ft above the fire. Calculate the wall flame height of the fire and determine

whether the flame will impinge upon the cable tray.

Solution

Purpose:

(1) Calculate the wall flame height.

(2) Determine whether the flame will impinge upon the cable tray.

Assumptions:

(1) Air is entrained only from one side during the combustion process.

(2) The fire is located at or near a wall configuration of a compartment that affects

the spread of the fire.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 04_Flame_Height_Calculations.xls (click on Wall_Flame _Height)

FDTs Input Parameters:

-Fuel spill volume (V) = 2 gallons

dike -Fuel Spill Area or Dike Area (A ) = 9.0 ft2

-Select Fuel Type: Transformer Oil, Hydrocarbon

Results*

Fue f(Wall) l Wall Fire Flame Height (H )

m (ft)

Cable Tray

Impingement 

Transformer Oil,

Hydrocarbon

3.0 (10.0) Yes

 *see spreadsheet on next page
4-8

Spreadsheet Calculations

FDT : 04_Flame_Height_Calculations.xls (click on Wall_Flame _Height) s

CHAPTER 4. ESTIMATING WALL FIRE FLAME HEIGHT 

Version 19l5D 

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Plli'\'IDI~tH lll Ell WCEll Silr~ Entlnd by 1U UtH. 

Plli'\'IDI~tH ln GREEII C EllS llr~ Automll11CIIII}' h iH,dtrom 1ll$ DRO P OOVVII f.1EIIU fo r11u Fll&l S&IHUd . 

. .:. 1 HbH\IH ltOI1j>ltV<IIH$ <I ~ cat:l 1.1t&d by1U plea ~ •Ht<Ud baH d Ol tJa ltH rn. d II ~ " Pit 

para•"&'" . n t $pl?a<th&t a; pl ~daut $&cue b at.to•:t &no" <IH b a w1o1g utrv 11 a o:tt('). 

Th c ... ), 1111U IIUP, ~ $. 0 1.:1 b& !?ad l=*'bl& <11 <U<II($1$ ~mao:. 

INPUT PARAMETERS 

F H I Sj> Ill Vo ltiiH (1/) 2 00 g.'lt)" FHI ~> III.oi.Jea r Ot:&.l'.IM ,'.,,W 9 .00 . 

1.1<16$ 61UIItj Rate 01 fHI II ") OD» l«atll•;ec 

E11'ectiJ& HMtOTCOIIIb"tDI OTFH I ~.,~ '"'"' I:J.t;g 

Elll pU~ Ut.'llt i,!:P) 0.1 m 

I Calculate II 

THERMAL PROP ERTlE$ FOR 

BURIIIIIG RATE DATA FOR LIQUID HYDROCARBOII FUELS 

O!M6111 

08~ ...... 

fHI r.1as' 6'" 119 Ra' ~at tll b"OH Bllp lltaiCOI$tllt Select Fuel Type 

, .... ;t gihl :t ) H .. ,. iJ;J,t;g) I:P 1m ' • Eiaruram.~3 

r.1 l 0.017 20.000 100 Scrdl to d~ r~d 11.1 1 yp~ UH n 

EUa•o l 0.0 IS 26.800 100 Oick on ·~ n 

6 1t.'IH 0.078 45,700 2.7 

6uze ~ 0.085 ,0,100 2.7 

na ~ 0.07' U ,700 1.9 

~ptiH 0 .101 U ,600 1.1 

XV'"H OD9 '0.800 u :. o:tn~ 0.041 25.800 1.9 

o• ~ 0.018 26.200 S.l 

OI:Q EU ~I 0.085 3 ' 2 00 0.7 

6uze ~ ODIS U ,700 3.6 

Ga>OIIH 0.055 43,700 2.1 

OH ~ OD» 43.200 3.5 

DIH~ I ODIS " ·'00 2.1 

JP-' 0.05 1 43.500 3.6 

JP .. 0.05' 43.000 1.6 TlaWbPII~I 0 11, Hy'tiiOCalbOI OD» ' 6 .000 0.7 

561 S III::OI Tla"DPIIU n •:1 0.005 28.100 100 

fH 10 11, HM1/V 0.035 39,700 1.7 

CUd! 0 11 0.034 ' 2.600 2.8 

lll ~ 0 1 OD» ' 6 .000 0.7 

UH ISI=*Ciftd ll ~ E1U1 11 ~ El' ~ E••1 11 ~ 

It~ tr~l"o2 : $.=?$1-im(b. ... .\('~ ~ l" <t~'C.:>n ~' ' =atN, >:». 
4-9

t-hat ~lease Rate calcUaticn 

*' ': S. P$ ~..._'\ ('(t=l'f:>i>~«t .:r.=rt~~~ 3'" :a v, 'l.\.l':. Fl:\IC 3-ZS. 

Q = m"AH. .... (1. e '"" j A .... 

Where Q =pod h hea release rae (kVV) 

m"= mass buninQ r.ne of tiel per urit surDce na (kWJT{-sec) 

AH..,..t= etf!cti'W hea ofcorrbustDn of tiel (kJ'<g) 

A= A .... = surDce area of pool fi~e @rea imoi'Wd in 'Wporizalion)(m') 

l4l = EmPrical co1'613nt(m ·) 

0= da~rofpod ire (dianEterimotwd n 'Wporizalion,ciroubrpool is assumed)(m) 

(Uq.~ids wth rel<ti'WiyhQh flash poilt,like11'3nsi:lnner 

oil req.~ire localized healing to actie'W ignition) 

Pcd Are D<rneter calculaticn 

= >(f~ 

0=>(4A "'J 

Where Al~.n = surface area ofpool ire (m") 

0= pool1i"e dianter (m) 

O= 1.032 m 

t-hat ~lease Rate calcUaicn 

Q = m"AH ..... (1·e ~u)A».o~ 

0= 771.52 kW 

t-hat ~lease Rate Per Lhit LE'flghof Are calculaticn 

0'= Oil 

731.26 Etuo'sec 

Where a= heat ~ease r.rte per unit length (kVl.O'm) 

Q = fi"e heat~elease r.ne oflhe fi~e !l<Vll) 

l= len~h oflhe h sruroe lfn) 

Are So..rce Lerg:h calcUaicn 

lx W= A.l~n 

lxW= 

L= 

0'= Oil 

0'= 

0.836 m" 

0.914 m 

843.75 k\JIO\n 

ESTIMATING WALL FIRE FLAME HEIGHT 

*' ': FI"A.t=l'f:>i> .:r.Hmd>:'c. . ·o" St.'lfbr, :l.\.l'.\ ;>~ :t- ).:.. 

H,...,.,= OD34 a l)':l 

Where H. ••• u,= wall fire 1ame hei~ (m) 

a= rae of heat ~ease perunt len~h ofthe h (kWtn) H,...,.,= OD34 "'~ 

Iii. liM 

The abo'W calcolalions are based on pinciples de'Wioped in the S FP E 1-bndbook of Fire 

Prttection &Qineff'inQ,3"' Ei::lition, 2002,and NFPAFi'e A-otectim 1-Bldbod<, 19"' 6:1ition, 2003. 

C31colalions are based m cenain assurrptions ald ha'W inherent lmitJ!ions. The results of 

such calcolaims mayormaynct ha'W reasonable prEdicti'W capa~lities i:lr a gi'Wn stuaim, ard 

shouH mlybe interpraed byan infonned user. 

Mlrugh each calcolalion in the sp-eadshea has been 'Wri,ed with the ~eslfts of hard cabutRDn, 

there is ro absolute gua~antee oflhe accU'3cyofthese calcolalions. 

Alyquestions,corrments, cmcems, and suggestims,orto repon an error(s)inthe spreadsheet, 

please send 3'1 Em<il to mO@flroQovormxs3@flroQOV. 
4-10

Example Problem 4.9-2

Problem Statement

A pool fire scenario arises from a transient combustible liquid spill. This event allows the fuel

contents of a 15 gallon can to form along a wall with an area of 30 ft . A cable tray is located 12 ft 2

above the fire. Determine the line wall fire flame height and whether the flame will impinge upon

the cable tray if the spilled liquids are (a) diesel, (b) acetone, and (c) methanol.

Solution

Purpose:

(1) Calculate the line wall fire flame height using three transient combustibles.

(2) Determine whether the flame will impinge upon the cable tray in each case.

Assumptions:

(1) Air is entrained only from one side during the combustion process.

(2) The fire is located at or near a wall configuration of a compartment

that affects the spread of the fire.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 04_Flame_Height_Calculations.xls (click on Wall_Line_Flame _Height)

FDT Input Parameters: s

-Fuel spill volume (V) = 15 gallons

dike -Fuel Spill Area or Dike Area (A ) = 30.0 ft2

-Select Fuel Type: Diesel, Acetone, and Methanol

Results*

Fue f(Wall Line) l Wall Line Fire Height (H )

m (ft)

Cable Tray

Impingement 

Diesel 3.8 (12.3) Yes

Acetone 2.44(8.0) No

Methanol 1.2 (3.8) No

*See spreadsheets on next page
4-11

Spreadsheet Calculations

FDT : 04_Flame_Height_Calculations.xls (click on Wall_Line_Flame _Height) s

(a) Diesel

CHAPTER 4. ESTIMATING LINE FIRE FLAME HEIGHT AGAINST THE WALL 

Ve<Sion 1805.0 

The following calculations estimate the line fire flame height against lhe wall. 

Parameters in YELLOW CELLS are Entered bythe User. 

Parameters in GREEN CEll$ are Automatically Selectedfrcm the DROP DOWN M ENUforthe Fuel Selected. 

All subsequeM oUiput \Glues are calculated bythe spreadsheet and based on wlues specified in the input 

parameters. This spreadsheet is protected and secure to a wid errors due to a wrong entry in a cell(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

Fuel Spill \A:IIume (\1,1 1500 galb" O.o5>38 Ito 

Fuel Spill .A"ea or Oib ~a (A.».n) 3000 ii' Z.18! hi ~ 

Mass Burning Rat»l of Fuel (m') 0045 tgllil ~~c 

Effective Heat of Combustion of Fuel (AH,..,,) 44400 •:J.t;g 

Errpirical Constant (kP) 2.111'1 

II Caluhtell 

THERMAL PROPERTIES FOR 

BURNING RATE DATA FOR LIQUID Hi DROCARBON FUELS 

Bnp1nca1 

Fuel Mass Burning Ra~ Heat of Combustion ConstaM Select Fuel Type 

m"(kghn1-sec) AH....,, (kJo1<g) kP(m 1

) • . Methanol 0017 20000 100 Scroll to desired fuel type then 

Ethanol 0015 26~00 100 Click on selection 

Bumne 0078 46.700 2.7 

Benzene 0085 40.100 2.7 

Hexane OD74 44,700 19 

Heptane 0.101 44~00 1.1 

~ene 009 40~00 1.4 

~one 0041 25~00 19 

Dioxane 0018 26~00 5.4 

DiethyBher 0085 34~00 0.7 

Benzene 0048 44,700 36 

Gasoline 0055 43.700 2.1 

Kerosene 0039 43~00 35 

Diesel 0046 44,400 2.1 

P-4 0051 43500 36 

P·5 OD54 43000 16 

ran sfonner Oil, Hydrocarbon 0039 48000 0.7 

61 Silicon Transfonner Auid 0005 28.100 100 

Fuel Oil, Heavy 0035 39.700 1.7 

Crude Oil OD34 42~00 2S 

lube Oil 0039 48000 0.7 

User Soeci,ed \I.Jiue Enter \I.Jiu e &Iter \I.Jiue Enter\lalue 

- .. 
4-12

Hut Rtlu 1t Rate 011cu1 a11o n 

~-.,~rc~:si=P=Htlltl>.-.:io. di=l h:fc-3:.:r.~'N;J 3 " =a:.:r. ~'\l'2 l'l:\it :t-ZS. 

a -m·t:, ....,, o.:- .4.. 

'lVhle a • pooiTII! hat1e1:a.e 1.'1' ;J:\t\1) 

Ill' • 111<1 6$ b' Ullg 1.'1' OT p~ I U It$ UT<t:.? aJ~a $ 9 ,111 :t ) t:,H .. _.• Tt CU ~ hatOTCOIIIbUU,_ OTfHI ;J;J,t;g) 

.t..,• A,"'-" • $ UTaO: aJ~a po I111e \1 1~<1 IUtOI1HI .. ll<tpOitaOH) (11 ) 

t;p • e111 ii. CO Ut.'llt {II ) 

0 • dblll ~' IOTpOOITte I$J hlll~~ llltJOt.r~d . 11<tp011Za1m , CICU.'IIpoOII$ <1 HIJI~ (~ ~~) 

(U:I••:I6 WIG I~ l.'ltl1~ If. •:" Tb$. POIIt lh 1JaiU PII ~ I 

111 1• 11e ca l~d haU1g b ~ •_;~•II)H) 

Pool Flrt thmtter 011cu1a1on 

.:.<J.., • .tO:t" 

O• 4.t.. ~) 

'Nhre A,"""• IT<t eaJea poo ltlle ~~ ) 

o- poo1111e dh•ll~ 1 ~~) 

0• LSU 111 

Hut Rtlu u Rate 011cu1a11on 

a ·m·t:,H....,t (H .o,:.") A""" 

a • H~VH •:'N 

H&at Rtlu 1t Rate ~r Unit Ltnn11l oT Fire 011c u1a11on 

a·· aJL 

'Nhle a· • hat te l?aH 1<1, p~l 'It 1:1911 $VWhl) 

a •Til! hat 1~1:a.e 1.'1' on e 111 e t:V'V) 

L• IHgU OTUe life $0UO: ~~) 

Fin s ouru Ltng11l 011cu1a11on 

LX W• AIM 

LX W• 

L• 

a· · aJL 

a·-

2.787 m" .. ~~3 Ill 

ESTIMATING LINE WALL FIRE FLAME HEIGHT ~'tr~rc~ NR"A ~Prctc-3:.:>r.Htlltl>.-.:fo.. 11" ad!'br, :l.'\)3 !"~ 3-13:. 

H • .,.. .. .,,. 0.0 17 a·:t.:. 

Whle H,.,.. .. .,,- wa ll111 e ll.'lllle ~•_;t II ) 

a· • 1<1, OT Hat te l?aH pe I U It I? 1(11i OT1ie llle .,W,tll) 

H ........ ,. o.ol7 a·"" 

IH~~: "~= H $ m 12.23 n IIJa 

ld.lil 

n e .. )OV~ ca ' 1.'10,_$ <II~ l>aH d 01 p iiiCj)l?$ d~ ~ tt ~d . U e S FPE Hauboo•: OT File 

PI ~COH EUIIIH fll(l, :f~ 6:1U,_ , 1002, <ti d IIFP A File P D'ctbl H<tl<lbOOI;, 19" 6:111),_ , 1003. 

at •L'~O" ' a1e baa d 0 1 cut111 a>Hmptb" a 1d •ave "hie 1t ltllltiO" ' · Th 1e' u t oT 

H e• cat:U.'IOH6 mar 01111 anou ave teaso1abl! pi~ U:U ~ cap .. u n h 1:11 a gvu $ll'l<tU)I.<tld 

•• ll b~ .,qm,d ){ <tlll 'b lll ~duet 

.:O.Mo •g • e<t:• al ' l.'ltb l " 1U 6prea<thet •a. bH 1 ~1m. d wu Ue teH It oT •a i d cat U.'IO,. , 

Que t 1o a1:4o1'' a~a1' e OT Qe cc•I.'IOf OT 1i H ca 'IO" · 

.:O.Iy q •H tbl$, O:tll IIIU~ . COIO:U$, <ti d H9_;!H OH$, Olb 1eporta1 ~11 (') . U e $p1e<t:l6het, 

pl!aH ~ ld <II e111 <1 llb IXI@IIC.gov OIIJIU 30 11C.gOV. 
4-13

FDT : 04_Flame_Height_Calculations.xls (click on Wall_Line_Flame _Height) s

(b) Acetone

CHAPTER 4. ESTIMATING LINE FIRE FLAME HEIGHT AGAINST THE WALL 

Version1805.0 

The following calculations estimate the line fire flame height against the wall. 

Parameters in YELL OW CELLS are Entered by the User. 

Parameters in GREEN CELLS ~e Automctically Selected from the DROP DOWN MENU for the Fuel Selected. 

All subsequent output values are calculated by the spreadsheet and based on values specified in the input 

parameters. This spreadsheet is protec~d and secure to avoid errors due to a wrong entrv in a cel(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

Fuel SpiiiVolume(V) 1500 gallons 0.0508 Ill 

Fuel Spill Atea or Dike Area (Au:t) 3000 ft' 2.787 Ill ~ 

Mass Burning RaM of Fuel(m'' 0.041 kg.tn2-sec 

Effective Heat of Combustion of Fuel (laH ~ 25800 k.Jol<g 

Empirical Constant (kP) 1.9 m 

II Calculate II 

lHERMAL PROPERTIES FOR 

BURNING RATE OAT A FOR LIQUID HYDROCARBON FUELS 

Empirical 

Fuel Mass Buming RaW Heat of Combustion C onsldnt Selett Fuel TYJ>e 

m"(ktimz·sec) lLHcd(kJA<g) kP(m .. ) I e.~ ia;;~ i 

Methanol 0.017 20.000 100 Strollto desired fuel typo 

Ethanol 0.015 26.800 100 Clit k on selection 

Butane 0.078 45.700 2.7 

Benzene 0.085 4:1,100 2.7 

Hexane 0.074 44,700 1.9 

Hepldne 0.101 44,6)0 1.1 

Xylene 0.09 43.800 1.4 

Acetone 0.041 25.800 1.9 

Dioxane O.o1B 26.200 5.4 

Diethy Ether 0.085 34.200 0.7 

Benzene 0.048 44,700 3.6 

Gasoline 0.055 43.700 2.1 

Kerosene 0.039 43.200 3.5 

Diesel 0.045 44,4:10 2.1 

JP-4 0.051 43.&10 3.6 

JP·5 0.054 43.000 1.6 

Transformer Oil, Hydrocarbon 0.039 43.000 0.7 

561 Silicon Transformer Fluid 0.005 28.100 100 

Fuel Oil, Heauy 0.035 39.700 1.7 

Crude Oil 0.034 42.f00 2.8 

Lube Oil 0.039 43.000 0.7 

User Soecified Value Enter Value Enter Value Enter Value : ='-' . . ~ .. . ' . . 
4-14

Hut Rtlu 1t Rate 011cu1 a11o n 

~-.,~rc~:si=P=Htlltl>.-.:io. di=l h:fc-3:.:r.~'N;J 3 " =a:.:r. ~'\l'2 l'l:\it :t-ZS. 

a -m·t:, ....,, o.:- .4.. 

'lVhle a • pooiTII! hat1e1:a.e 1.'1' ;J:\t\1) 

Ill' • 111<1 6$ b' Ullg 1.'1' OT p~ I U It$ UT<t:.? aJ~a $ 9 ,111 :t ) t:,H .. _.• Tt CU ~ hatOTCOIIIbUU,_ OTfHI ;J;J,t;g) 

.t..,• A,"'-" • $ UTaO: aJ~a po I111e \1 1~<1 IUtOI1HI .. ll<tpOitaOH) (11 ) 

t;p • e111 ii. CO Ut.'llt {II ) 

0 • dblll ~' IOTpOOITte I$J hlll~~ llltJOt.r~d . 11<tp011Za1m , CICU.'IIpoOII$ <1 HIJI~ (~ ~~) 

(U:I••:I6 WIG I~ l.'ltl1~ If. •:" Tb$. POIIt lh 1JaiU PII ~ I 

111 1• 11e ca l~d haU1g b ~ •_;~•II)H) 

Pool Flrt thmtter 011cu1a1on 

.:.<J.., • .tO:t" 

O• 4.t.. ~) 

'Nhre A,"""• IT<t eaJea poo ltlle ~~ ) 

o- poo1111e dh•ll~ 1 ~~) 

0• LSU 111 

Hut Rtlu u Rate 011cu1a11on 

a ·m·t:,H....,t (H .o,:.") A""" 

a • 8~$.34 •:'N 

H&at Rtlu 1t Rate ~r Unit Ltnn11l oT Fire 011c u1a11on 

a·· aJL 

'Nhle a· • hat te l?aH 1<1, p~l 'It 1:1911 $VWhl) 

a •Til! hat 1~1:a.e 1.'1' on e 111 e t:V'V) 

L• IHgU OTUe life $0UO: ~~) 

Fin s ouru Ltng11l 011cu1a11on 

LX W• AIM 

LX W• 

L• 

a· · aJL 

a·-

2.787 m" .. ~~3 Ill 

ESTIMATING LINE WALL FIRE FLAME HEIGHT ~'tr~rc~ NR"A ~Prctc-3:.:>r.Htlltl>.-.:fo.. 11" ad!'br, :l.'\)3 !"~ 3-13:. 

H • .,.. .. .,,. 0.0 17 a·:t.:. 

Whle H,.,.. .. .,,- wa ll111 e ll.'lllle ~•_;t II ) 

a· • 1<1, OT Hat te l?aH pe I U It I? 1(11i OT1ie llle .,W,tll) 

H ........ ,. o.ol7 a·"" 

IH~~: "~= 2.44 m s.eo n IIJa 

ld.lil 

n e .. )OV~ ca ' 1.'10,_$ <II~ l>aH d 01 p iiiCj)l?$ d~ ~ tt ~d . U e S FPE Hauboo•: OT File 

PI ~COH EUIIIH fll(l, :f~ 6:1U,_ , 1002, <ti d IIFP A File P D'ctbl H<tl<lbOOI;, 19" 6:111),_ , 1003. 

at •L'~O" ' a1e baa d 0 1 cut111 a>Hmptb" a 1d •ave "hie 1t ltllltiO" ' · Th 1e' u t oT 

H e• cat:U.'IOH6 mar 01111 anou ave teaso1abl! pi~ U:U ~ cap .. u n h 1:11 a gvu $ll'l<tU)I.<tld 

•• ll b~ .,qm,d ){ <tlll 'b lll ~duet 

.:O.Mo •g • e<t:• al ' l.'ltb l " 1U 6prea<thet •a. bH 1 ~1m. d wu Ue teH It oT •a i d cat U.'IO,. , 

Que t 1o a1:4o1'' a~a1' e OT Qe cc•I.'IOf OT 1i H ca 'IO" · 

.:O.Iy q •H tbl$, O:tll IIIU~ . COIO:U$, <ti d H9_;!H OH$, Olb 1eporta1 ~11 (') . U e $p1e<t:l6het, 

pl!aH ~ ld <II e111 <1 llb IXI@IIC.gov OIIJIU 30 11C.gOV. 
4-15

FDT : 04_Flame_Height_Calculations.xls (click on Wall_Line_Flame _Height) s

(c) Methanol

CHAPTER 4. ESTIMATING LINE FIRE FLAME HEIGHT AGAINST THE WALL 

Ve<Sion 1805.0 

The following calculations estimate the line fire flame height against lhe wall. 

Parameters in YELLOW CELLS are Entered bythe User. 

Parameters in GREEN CELLS are Automatically Selectedfrcm the DROP DOWN M ENUforthe Fuel Selected . 

.All subsequeM oUiput \Glues are calculated bythe spreadsheet and based on wlues specified in the input 

parameters. This spreadsheet is pr®lcted and secure to a wid errors due ro a wrong eMryin a cell(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

Fuel Spill \A:IIume (\1,1 1500 galb" O.o5>38 hi 

Fuel Spill .A-ea or Oib .A"ea (A.».n) 3000 it Z.78! .,., ~ 

Mass Burning Rat»l of Fuel (m') 0017 tgllil "~c 

Effective Heat of Combustion of Fuel (AH,..,,) 20000 I:J.t;g 

Errpirical Constant (kP) 100 Ill 

II Cal<thtell 

THERMAL PROPERTIES FOR 

BURNING RATE DATA FOR LIQUID Hi DROCARBON FUELS 

Empirical 

Fuel Mass Burning Ra~ Heat of Combustion ConstaM Select Fuel Type 

m"(kghn1-sec) AH....,, (kJo1<g) kP(m 1

) . Methanol 0017 20000 100 Scroll to desired fuel type then 

Ethanol 0015 26~00 100 Click on selection 

Bumne 0078 46.700 2.7 

Benzene 0085 40.100 2.7 

Hexane OD74 44,700 19 

Heptane 0.101 44~00 1.1 

~ene 009 40~00 1.4 

~one 0041 25~00 19 

Dioxane 0018 26~00 5.4 

DiethyBher 0085 34~00 0.7 

Benzene 0048 44,700 36 

Gasoline 0055 43.700 2.1 

Kerosene 0039 43~00 35 

Diesel 0046 44,400 2.1 

P·4 0051 43500 36 

P·5 OD54 43000 16 

ran sfonner Oil, Hydrocarbon 0039 48000 0.7 

61 Silicon Transfonner Auid 0005 28.100 100 

Fuel Oil, Heavy 0035 39.700 1.7 

Crude Oil OD34 42~00 2S 

lube Oil 0039 48000 0.7 

User Soeci,ed \I.Jiue Enter \I.Jiu e &Iter \I.Jiue Enter\lalue . .. 
4-16

Hut Rtlu 1t Rate 011cu1 a11o n 

~-.,~rc~:si=P=Htlltl>.-.:io. di=l h:fc-3:.:r.~'N;J 3 " =a:.:r. ~'\l'2 l'l:\it :t-ZS. 

a -m·t:, ....,, o.:- .4.. 

'lVhle a • pooiTII! hat1e1:a.e 1.'1' ;J:\t\1) 

Ill' • 111<1 6$ b' Ullg 1.'1' OT p~ I U It$ UT<t:.? aJ~a $ 9 ,111 :t ) t:,H .. _.• Tt CU ~ hatOTCOIIIbUU,_ OTfHI ;J;J,t;g) 

.t..,• A,"'-" • $ UTaO: aJ~a po I111e \1 1~<1 IUtOI1HI .. ll<tpOitaOH) (11 ) 

t;p • e111 ii. CO Ut.'llt {II ) 

0 • dblll ~' IOTpOOITte I$J hlll~~ llltJOt.r~d . 11<tp011Za1m , CICU.'IIpoOII$ <1 HIJI~ (~ ~~) 

(U:I••:I6 WIG I~ l.'ltl1~ If. •:" Tb$. POIIt lh 1JaiU PII ~ I 

111 1• 11e ca l~d haU1g b ~ •_;~•II)H) 

Pool Flrt thmtter 011cu1a1on 

.:.<J.., • .tO:t" 

O• 4.t.. ~) 

'Nhre A,"""• IT<t eaJea poo ltlle ~~ ) 

o- poo1111e dh•ll~ 1 ~~) 

0• LSU 111 

Hut Rtlu u Rate 011cu1a11on 

a ·m·t:,H....,t (H .o,:.") A""" 

a • ~47 ~ 1 •:'N 

H&at Rtlu 1t Rate ~r Unit Ltnn11l oT Fire 011c u1a11on 

a·· aJL 

'Nhle a· • hat te l?aH 1<1, p~l 'It 1:1911 $VWhl) 

a •Til! hat 1~1:a.e 1.'1' on e 111 e t:V'V) 

L• IHgU OTUe life $0UO: ~~) 

Fin s ouru Ltng11l 011cu1a11on 

LX W• AIM 

LX W• 

L• 

a· · aJL 

a·-

2.787 m" .. ~~~ Ill 

ESTIMATING LINE WALL FIRE FLAME HEIGHT ~'tr~rc~ NR"A ~Prctc-3:.:>r.Htlltl>.-.:fo.. 11" ad!'br, :l.'\)3 !"~ 3-13:. 

H • .,.. .. .,,. 0.0 17 a·:t.:. 

Whle H,.,.. .. .,,- wa ll111 e ll.'lllle ~•_;t II ) 

a· • 1<1, OT Hat te l?aH pe I U It I? 1(11i OT1ie llle .,W,tll) 

H ........ ,. o.ol7 a·"" 

IH~~: "~= 1.17 m u 2n IIJa 

ld.lil 

n e .. )OV~ ca ' 1.'10,_$ <II~ l>aH d 01 p iiiCj)l?$ d~ ~ tt ~d . U e S FPE Hauboo•: OT File 

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pl!aH ~ ld <II e111 <1 llb IXI@IIC.gov OIIJIU 30 11C.gOV. 
4-17

Example Problem 4.9-3

Problem Statement

A pool fire scenario arises from a rupture in a diesel generator fuel line. This event allows diesel

fuel to spill 1.5 gallons along the corner of walls with an area of 10 ft . An unprotected junction box 2

is located 12 ft above the fire. Determine whether the flame will impinge upon the junction box.

Solution

Purpose:

(1) Calculate the line wall fire flame height.

(2) Determine whether the flame will impinge upon the junction box.

Assumptions:

(1) Air is entrained only from one side during the combustion process.

(2) The fire is located at or near a wall configuration of a compartment that affects

the spread of the fire.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 04_Flame_Height_Calculations.xls (click on Corner_Flame _Height)

FDTs Input Parameters:

-Fuel spill volume (V) = 1.5 gallons

dike -Fuel Spill Area or Dike Area (A ) = 10 ft2

-Select Fuel Type: Diesel

Results*

Fue f(Corner) l Corner Fire Flame Height (H )

m (ft)

Junction Box

Impingement 

Diesel 6.4 (21.1) Yes

 *see spreadsheet on next page
4-18

Spreadsheet Calculations

FDT : 04_Flame_Height_Calculations.xls (click on Corner_Flame _Height) s

CHAPTER 4. ESTIMATING CORNER FIRE FLAME HEIGHT 

Version 19l5.0 

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THERMAL PROPERTIES FOR 

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BURIIIIIG RATE DATA FOR U2 UID HYDRo::ARBOII FUELS 

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d~ 0 1 0.034 42.600 

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Oick on n 
4-19

Heat Release Rate Calctllation 

Reference: SFPE HJndboohof 1ft Prottction Enqineerinq, 3 ,.. Edition, 2002, Page ~25. 

Where Q = pool fire heat release rate (kW) 

m" = mass burning rate of fuel per unit surlace area (kg/m 2-sec) 

4-lc.w= effecti~~e heat of combustion of fuel (kJ/kg) 

A1= ~~t~ = surlace area of pool fire (area involved in vaporization) (m 2

) 

k ~ = empirical constant (m _,) 

0 =diameter of pool fire (diameter involved in vaporization, circular pool is assumed) (m) 

(liquids '>,A,(th relatively high flash point, like transformer 

Pool Fire Diameter Calc ulation 

dl ~ = 110 2/4 

D = v(41\:,.,l") 

oil require localized heating to achieve ignition) 

Where 11 ~ = surface area of pool fire (m ~ 

D = pool fire diamter (m) 

D= 1-088 m 

Heat Release Rate Calc ulation 

Q = m"tti .-(1-e~" ")A"'" 

Q = 1667-09 kW 

ESTIMATING CORNER FIRE FLAIVE HEIGHT 

1580-10 Btu/sec 

Reference: 1-/eset~ti and Tohooaqa, 'M:Io\?litlq ofTud:Julent Dilfusion Rat~tes and 1ft PluMes brthe Analy$sof fife Gro...th,' 

Growth,' Pro oee ding of the 21 ~~'~ NJ tional Heat Transfer Cbnfe~noe, At~te rican So ckty of ~chanical Enqinee~ (A SME), 1 983. 

,. Hr(com l)= 0.075 Q 

Where Q = heat release rate oft he fire (kVV) 

0.075 Q•• 

The above calculations are based on principles developed in the SFP E Hand book of Fire 

P rotedion Engineering, 3 r.l Edition, 2002 and Hesemi and T okunage, 1983. 

Calculations are based on certain assumptions and have inherent limitations. The results of 

such calculations may or may not have reasonable predictive capabilities for a given situation, 

and should only be interpreted by an informed user. 

Although each calculation in the spreadsheet has been verified '>,A,(th the results of hand calculation, 

there is no absolute guarantee of the accuracy of these calculations. 

Any questions, comments, concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an em ail to nxi@nrc.gov or m xs3@nrc.gov. 

5-1

CHAPTER 5. ESTIMATING RADIANT HEAT FLUX

FROM FIRE TO A TARGET FUEL

5.1 Objectives

This chapter has the following objectives:

• Introduce the three modes of heat transfer.

• Explain how to calculate the heat flux from a flame to a target outside the flame.

• Discuss point source radiation models and solid flame radiation models.

• Identify the difference between solid flame radiation models at ground level and solid flame

radiation models above ground level with and without wind.

• Define relevant terms, including, conduction, convection, radiation, heat flux, emissive power,

and configuration factor.

5.2 Introduction

Fire normally grows and spreads by direct burning, which results from impingement of the flame

on combustible materials, or from heat transfer to other combustibles by means of conduction,

convection, or radiation. All three of these modes of heat transfer may be significant, depending

on the specifics of a given fire scenario. Conduction is particularly important in allowing heat to

pass through a solid barrier (e.g., fire wall) to ignite material on the other side. Nevertheless, most

of the heat transfer in fires typically occurs by means of convection and/or radiation. In fact, it is

estimated that in most fires, approximate 70-percent of the heat emanates by convection (heat

transfer through a moving gas or liquid). Consider, for example, a scenario in which a fire produces

hot gas which is less dense than the surrounding air. This hot gas then rises, carrying heat. The

hot products of combustion rising from a fire typically have a temperature in the range of

800–1,200 °C (1,472–2,192 °F) and a density that is one-quarter that of ambient air. In the third

mode of heat transfer, known as radiation, radiated heat is transferred directly to nearby objects.

One type of radiation, known as thermal radiation, is the significant mode of heat transfer for

situations in which a target is located laterally to the exposure fire source. This would be the case,

for example, for a floor-based fire adjacent to an electrical cabinet or a vertical cable tray in a large

compartment. Thermal radiation is electromagnetic energy occurring in wavelengths from 2 to

16 m (infrared). It is the net result of radiation emitted by the radiating substances such as water

2 2 (H O), carbon dioxide (CO ), and soot in the flame.

Chapter 2 discussed various methods of predicting the temperature of the hot gas layer and the

height of the smoke layer in a room fire with natural or forced ventilation. However, those methods

are not applicable when analyzing a fire scenario in a very large open space or compartment.

In large spaces, such as the reactor building in a boiling water reactor (BWR) or an open space in

a turbine building, the volume of the space is too large for a uniform hot gas layer to accumulate.

For such scenarios, fire protection engineers must analyze other forms of heat transfer, such as

radiation. A floor-mounted electrical cabinet is an example of a ground-level target. A typical target

above ground level is an overhead cable tray.
The configuration factor is a purely geometric quantity, which gives the fraction of the radiation 1

leaving one surface that strikes another surface directly.

5-2

5.3 Critical Heat Flux to a Target

Radiation from a flame, or any hot gas, is driven by its temperature and emissivity. The emissivity

is a measure of how well the hot gas emits thermal radiation (emissivity is defined as the ratio of

radiant energy emitted by a surface to that emitted by a black body of the same temperature).

Emmisivity is reported as a value between 0 and 1, with 1 being a perfect radiator. The radiation

that an observer feels is affected by the flame temperature and size (height) of the flame.

The incident heat flux (the rate of heat transfer per unit area that is normal to the direction of heat

flow. It is a total of heat transmitted by radiation, conduction, and convection) required to raise the

surface of a target to a critical temperature is termed the critical heat flux. Measured critical heat

flux levels for representative cable samples typically range from 15 to 25 kW/m (1.32 to 2.2 Btu/ft -

2 2

sec). For screening purposes, it is appropriate to use value of 10 kW/m (0.88 Btu/ft -sec) for IEEE2 2

383 qualified cable and 5 kW/m (0.44 Btu/ft -sec) for IEEE-383 unqualified cable. These values 2 2

are consistent with selected damage temperatures for both types of cables based on the Electrical

Power Research Institute (EPRI), “Fire-Induced Vulnerability Evaluation (FIVE),” methodology.

Researchers have developed numerous methods to calculate the heat flux from a flame to a target

located outside the flame. Flames have been represented by cylinders, cones, planes, and point

sources in an attempt to evaluate the effective configuration factors between the flame and the 1

target. Available predictive methods range from those that are very simple to others that are very

complex and involve correlations, detailed solutions to the equations of radiative heat transfer, and

computational fluid mechanics. Routine FHAs are most often performed using correlationally based

approaches, because of the limited goals of the analyses and the limited resources available for

routine evaluation. As a result of their widespread use, a great deal of effort has gone into the

development of these methods. Burning rates, flame heights, and radiative heat fluxes are routinely

predicted using these approaches.

Fire involving flammable and combustible liquids typically have higher heat release rates (for the

same area of fuel involved) than ordinary combustibles fires. The flame from a liquid fire is typically

taller, making it a better radiator. Hydrocarbon liquid fires are also quite luminous because of the

quantity of soot in the flames. Sooty fires are better emitters of thermal radiation. Thus, an

observer approaching a flammable/combustible liquid fire feels more heat than an observer

approaching an ordinary combustibles fire of comparable size.

The methods presented in this chapter are drawn from the SFPE Handbook of Fire Protection

Engineering, 3 Edition, 2002, which examines the accuracy of these methods by comparisons rd

with available experimental data (these methods also presented in the SFPE Engineering Guide,

“Assessing Flame Radiation to External Targets from Pool Fires,” June 1999).
More realistic radiator shapes give rise to very complex configuration factor equations. 2

5-3

5.3.1 Point Source Radiation Model

A point source estimate of radiant flux is conceptually the simplest representation configurational

model of a radiant source used in calculating the heat flux from a flame to target located outside

the flame. To predict the thermal radiation field of flames, it is customary to model the flame based

on the point source located at the center of a flame . The point source model provides a simple 2

relationship that varies as the inverse square of the distance, R. For an actual point source of

radiation or a spherical source of radiation, the distance R is simply the distance from the point or

from the center of the sphere to the target.

The thermal radiation hazard from a fire depends on a number of parameters, including the

composition of the fuel, the size and the shape of the fire, its duration, proximity to the object at risk,

and thermal characteristics of the object exposed to the fire. The point source method may be used

for either fixed or transient combustibles. They may involve an electrical cabinet, pump, liquid spill,

or intervening combustible at some elevation above the floor. For example, the top of a switchgear

or motor control center (MCC) cabinet is a potential location for the point source of a postulated fire

in this type of equipment. By contrast, the point source of a transient combustible liquid spill or

pump fire is at the floor.

The point source model assumes that radiant energy is released at a point located at the center of

the fire. The radiant heat flux at any distance from the source fire is inversely related to the

horizontal separation distance (R), by the following equation (Drysdale, 1998):

 (5-1) 

Where:

= radiant heat flux (kW/m )

2

 = heat release rate of the fire (kW)

R = radial distance from the center of the flame to the edge of the target (m)

r

 = fraction of total energy radiated

r

In general, depends on the fuel, flame size, and flame configuration, and can vary from

approximately 0.15 for low-sooting fuels (e.g., alcohol) to 0.60 for high sooting fuels (e.g.,

hydrocarbons). For large fires (several meters in diameter), cold soot enveloping the luminous

r

flames can reduce considerably. See Figure 5-1 for a graphic representation of the relevant

nomenclature.
5-4

Figure 5-1 Radiant Heat Flux from a Pool Fire

to a Floor-Based Target Fuel (Point Source Model)

The HRR of a fire can be determined by laboratory or field testing. In the absence of experimental

data, the maximum HRR for the fire , is given by the following equation (Babrauskas, 1995):

(5-2)

Where:

 = heat release rate of the fire (kW)

= burning or mass loss rate per unit area per unit time (kg/m -sec) 2

Hc,eff = effective heat of combustion (kJ/kg)

Af = horizontal burning area of the fuel (m )

2

k$= empirical constant (m )

-1

D = diameter of burning area (m)

For non-circular pools, the effective diameter is defined as the diameter of a circular pool with an

area equal to the actual pool area, given by the following equation:

 (5-3) 

Where:

Af = surface area of the non-circular pool (m )

2

D = diameter of the fire (m)
5-5

5.3.2 Solid Flame Radiation Model with Target At and Above Ground Level

The solid flame spreadsheet associated with this chapter provides a detailed method for assessing

the impact of radiation from pool fires to potential targets using configuration factor algebra. This

method covers a range of detailed calculations, some of which are most appropriate for first order

initial hazard assessments, while others are capable of more accurate predictions.

The solid flame model assumes that, (1) the fire can be represented by a solid body of a simple

geometrical shape, (2) thermal radiation is emitted from its surface, and, (3) non-visible gases do

not emit much radiation. (See Figures 5-2 and 5-3 for general nomenclature.) To ensure that the

fire volume is not neglected, the model must account for the volume because a portion of the fire

may be obscured as seen from the target. The intensity of thermal radiation from the pool fire to

an element outside the flame envelope for no-wind conditions and for windblown flames is given

by the following equation (Beyler, 2002):

 (5-4)

Where:

= incident radiative heat flux (kW/m )

2

E = average emissive power at flame surface (kW/m )

2

1 2 6

F = configuration factor

Figure 5-2 Solid Flame Radiation Model with No Wind

and Target at Ground Level
5-6

Figure 5-3 Solid Flame Radiation Model with No Wind

and Target Above Ground

5.3.2.1 Emissive Power

Emissive power is the total radiative power leaving the surface of the fire per unit area per unit time.

Emissive power can be calculated using of Stefan’s law, which gives the radiation of a black body

in relation to its temperature. Because a fire is not a perfect black body (black body is defined as

a perfect radiator; a surface with an emissivity of unity and, therefore, a reflectivity of zero),

the emissive power is a fraction ( ) of the black body radiation (Beyler, 2002):

 (5-5)

Where:

E = flame emissive power (kW/m )

2

 = flame emissivity

 = Stefan-Boltzmann constant = 5.67 x 10 (kW/m -K )

-11 2 4

T = temperature of the fire (K)
The configuration factor is also commonly referred to as the “view factor”.

3

5-7

The use of the Stefan-Boltzmann constant to calculate radiation heat transfer requires knowledge

of the temperature and emissivity of the fire; however, turbulent mixing causes the fire temperature

to vary. Consequently, Shokri and Beyler (1989) correlated experimental data of flame radiation

to external targets in terms of an average emissive power of the flame. For that correlation, the

flame is assumed to be a cylindrical, black body, homogeneous radiator with an average emissive

power. Thus, effective power of the pool fire in terms of effective diameter is given by:

 (5-6)

Where:

E = flame emissive power (kW/m )

2

D = diameter of pool fire (m)

This represents the average emissive power over the whole of the flame and is significantly less

than the emissive power that can be attained locally. The emissive power is further reduced with

increasing pool diameter as a result of the increasing prominence of black smoke outside the flame,

which obscures the radiation from the luminous flame.

For non-circular pools, the effective diameter is defined as the diameter of a circular pool with an

area equal to the actual pool area given by Equation 5-3.

1 2 6

5.3.2.2 Configuration Factor F under Wind-Free Conditions

The configuration factor is a purely geometric quantity, which provides the fraction of the radiation 3

leaving one surface that strikes another surface directly. In other words the configuration factor

gives the fraction of hemispherical surface area seen by one differential element when looking at

another differential element on the hemisphere.

The configuration factor is a function of target location, flame size (height), and fire diameter, and

is a value between 0 and 1. When the target is very close to the flame, the configuration factor

approaches 1, since everything viewed by the target is the flame. The flame is idealized with a

diameter f equal to the pool diameter, D, and a height equal to the flame height, H . If the pool has

a length-to-width ratio near 1, an equivalent area circular source can be used in determining the

f

flame length, H , for non-circular pools. (See Figure 5-4 and 5-5 for general definitions applicable

to the cylindrical flame model under wind-free conditions.)
5-8

Figure 5-4 Cylindrical Flame Shape Configuration Factor Geometry

for Vertical and Horizontal Targets at Ground Level with No Wind

Figure 5-5 Cylindrical Flame Shape Configuration Factor Geometry

for Vertical and Horizontal Targets Above Ground with No Wind
5-9

Flame height of the pool fire is then determined using the following correlation (Heskestad, 1995):

 (5-8)

Where:

Hf = flame height (m)

 = heat release rate of the fire (kW)

D = diameter of the burning area (m)

The HRR of the fire can be determined by laboratory or field testing. In the absence of

experimental data, the maximum HRR for the fire , is given by Equation 5-2.

The radiation exchange factor between a fire and an element outside the fire depends on the shape

of the flame, the relative distance between the fire and the receiving element, and the relative

orientation of the element. The turbulent diffusion flame can be approximated by a cylinder. Under

wind-free conditions, the cylinder is vertical (Figure 5-4). If the target is either at ground level or at

the flame height, a single cylinder can represent the flame. However, if the target is above the

ground, two cylinders should be used to represent the flame.

For horizontal and vertical target orientations at ground level with no-wind conditions, given the

1 2 6

diameter and height of the flame, the configuration (or view factor) F under wind-free conditions

is determined using the following equations related to cylindrical radiation sources (Beyler, 2002):

(5-9)

(5-10)

Where:

And:

L = the distance between the center of the cylinder (flame) to the target (m)

Hf = the height of the cylinder (flame) (m)

D = the cylinder (flame) diameter (m)
5-10

The maximum configuration factor (or view factor) at a point is given by the vectorial sum of the

horizontal and vertical configuration factors:

 (5-11)

As previously stated, for targets above the ground, two cylinders should be used to represent the

flame. In such instances, one cylinder represents the flame below the height of the target, while

the other represents the flame above the height of the target (See Figure 5-5). Thus, the following

expressions are used to estimate the configuration factor (or view factor) under wind-free conditions

for targets above ground level:

 (5-12)

Where:

 (5-13)

Where:

And:

L = the distance between the center of the cylinder (flame) to the target (m)

Hf = the height of the cylinder (flame) (m)

D = the cylinder (flame) diameter (m)

The total configuration factor or (view factor) at a point is given by the sum of two configuration

factor as follows:

 (5-14)
5-11

1 2 6

5.3.2.3 Configuration Factor F in Presence of Wind

As discussed in pervious section, in the solid flame radiation model the turbulent flame is

approximated by a cylinder. Under wind-free conditions, the cylinder is vertical, in the presence of

wind, the flame may not remain vertical and thermal radiation to the surrounding objects will change

in the presence of a significant wind. The flame actually follows a curved path and makes an angle

of tilt or an angle of deflection approximate to its curved path. Figures 5-6 and 5-7 describe the

w

flame configuration in presence of wind velocity (u ) for target at and above ground level.

Figure 5-6 Solid Flame Radiation Model in Presence of Wind 

and Target Above Ground Level

Figure 5-7 Solid Flame Radiation Model in Presence of Wind 

and Target at Ground Level
5-12

For horizontal and vertical target orientations at ground level in presence of wind, the expression

for estimating the configuration factors is expressed by the following equations (Beyler, 2002):

 (5-15)

 (5-16)

Where:

And:

Hf = the height of the tilted cylinder (flame) (m)

r = the cylinder (flame) radius (m)

R = distance from center of the pool fire to edge of the target (m)

θ = flame title or angle of deflection (radians)

The maximum configuration factor for a target at ground level in the presence of wind at a point

is given by the vectorial sum of the horizontal and vertical configuration factors:

 (5-17)
5-13

For targets above the ground in presence of wind, two cylinders must be used to represent the

flame. In such instances, one cylinder represents the flame below the height of the target, while

the other represents the flame above the height of the target. The following expressions are used

to estimate the configuration or view factor in presence of wind for targets above ground level:

 (5-18)

 (5-19)

Where:

And:

H1 f1 = H = vertical distance of target from ground level (m)

Hf = the height of the tilted cylinder (flame) (m)

r = the cylinder (flame) radius (m)

R = distance from center of the pool fire to edge of the target (m)

θ = flame title or angle of deflection (radians)
5-14

The total configuration or view factor at a point is given by the sum of two configuration factors,

as follows:

 (5-20)

In presence of wind, the expression for estimating flame height is expressed by the following

correlation, based on the experimental data (Thomas, 1962):

 (5-21)

Where:

D = diameter of pool fire (m)

= mass burning rate of fuel (kg/m -sec) 2

a

 = ambient air density (kg/m )

3

g = gravitational acceleration (m/sec )

2

u* = nondimensional wind velocity

The nondimensional wind velocity is given by:

 (5-22)

Where:

u* = nondimensional wind velocity

uw = wind speed or wind velocity (m/sec)

g = gravitational acceleration (m/sec )

2

= mass burning rate of fuel (kg/m -sec) 2

D = diameter of pool fire (m)

 = density of ambient air (kg/m )

3

The correlation relating to angle of tilt or angle of deflection ( ), of the flame from the vertical

are expressed by the following equations based on the American Gas Association (AGA) data:

 (5-23)

Where:

 = angle of tilt or angle of deflection (radians)

u* = nondimensional wind velocity
5-15

5.4 Method of Estimating Thermal Radiation from Hydrocarbon Fireball

For industrial processes, many substances that are gases at ambient conditions are stored in

container or vessel under pressure in a saturated liquid/vapor form. A rupture of a such vessel will

result in a violent incident as the liquid expands into its gaseous form. This phase change forms

blast waves with energy equivalent to the change in internal energy of the liquid/vapor; this

phenomenon is called the BLEVE. BLEVE is an acronym of Boiling Liquid, Expanding Vapor

Explosion. National Fire Protection Association (NFPA), defined a BLEVE as the failure of a major

container into two or more pieces, occurring at a moment when the contained liquid is at

temperature above its boiling point at normal atmospheric pressure. Typically, a BLEVE occurs in

a metal container that has been overheated above 538 °C (1,000 °F) (Nolan 1996). The metal may

not be able to withstand the internal stress and therefore failure occurs. The contained liquid space

of the vessel normally acts as a heat absorber, so the wetted portion of the container is usually not

at risk, only the surfaces of the internal vapor space. Most BLEVEs occur when containers are less

than 1⁄2 to a full of liquid.

A container can fail for a number of reasons. It can be damaged by impact from an object, thus

causing a crack to develop and grow, either as a result of internal pressure, vessel material

brittleness, or both. Thus, the container may rupture completely after impact. Weakening the

container’s metal beyond the point at which it can withstand internal pressure can also cause large

cracks, or even cause the container to separate into two or more pieces. Weakening can result

from corrosion, internal overheating, or manufacturing defects, etc.

5.4.1 Radiation Due to BLEVEs with Accompanying Fireball

In additional to the container becoming a projectile, the hazard posed by a BLEVE is the fireball and

the resulting radiation. The rapid failure of the container is followed by a fireball or major fire, which

produces a powerful radiant heat flux.

Four parameters often used to determine a fireball’s thermal radiation hazard are the mass of fuel

involved and the fireball’s diameter, duration, and thermal emissive power. Radiation hazards can

then be calculated from empirical relation.

Radiation received by an object relatively distant from the fireball can be calculated by the following

expression (Hasegawa and Sato, 1977 and Roberts, 1982):

 (5-24)

Where:

= thermal radiation from fireball (kW/m )

2

mF = mass of fuel vapor (kg)

R = distance from the center of the fireball to the target (m)
5-16

The distance from the center of the fireball to the target is given by the following relation:

 (5-25)

Where:

R = distance from the center of the fireball to the target (m)

Zp = fireball flame height (m)

L = distance at ground level from the origin (m)

The fireball flame height is given by the following expression (Fay and Lewis 1976):

 (5-26)

Where:

Zp = fireball flame height (m)

VF = volume of fuel vapor (m )

3

The volume of fireball can be calculated from the following relation:

 (5-27)

Where:

VF = volume of fuel vapor (m )

3

mF = mass of fuel vapor (kg)

F

 = fuel vapor density (kg/m )

3
Common jet fuel. 4

5-17

5.5 Assumptions and Limitations

The methods discussed in this chapter are subject to several assumptions and limitations.

The following assumption applies to all radiation models:

(1) The pool is circular or nearly circular.

The following assumptions and limitations apply to point source radiation models:

(1) Except near the base of pool fires, radiation to the surroundings can be approximated as

being isotropic or emanating from a point source.

(2) The point source model overestimates the intensity of thermal radiation at the observer’s

(target) locations close to the fire. This is primarily because the near-field radiation is

greatly influenced by the flame size, shape, and tilt, as well as the relative orientation of the

observer (target).

(3) A theoretical analysis of radiation from small pool fire by Modak (1977) indicated that the

point source model is within 5-percent the correct incident heat flux when L/D >2.5.

(4) The energy radiated from the flame is a specified fraction of the energy released during

combustion.

(5) The model can be used to determine thermal radiation hazards in scenarios for which a

conservative estimate of the hazard is generally acceptable.

The following limitation applies to solid flame radiation models at and above ground level:

(1) The correlation of emissive power was developed on the basis of data from experiments

that included kerosene, fuel oil, gasoline, JP-4, JP-5 , and liquified natural gas (LNG). With 4

the exception of the LNG, these are quite luminous flames, so the correlation should be

suitable for most fuels. The pool diameters ranged from 1 to 50 m.

5.6 Required Input for Spreadsheet Calculations

The user must obtain the following information before using the spreadsheet:

(1) fuel type (material)

(2) fuel spill area or curbed area (ft )

2

(3) distance between fire and target (ft)

(4) vertical distance of target from ground level (ft)

(5) wind speed (ft/min)

5.7 Cautions

(1) Use the appropriate spreadsheet (05.1_Heat_Flux_Calculations_Wind_Free.xls or

05.2_Heat_Flux_Calculations_Wind) on the CD-ROM for the calculation.

(2) Make sure units are correct on input parameters.
5-18

5.8 Summary

Estimating the thermal radiation field surrounding a fire involves the following steps:

(1) Characterize the geometry of the pool fire; that is, determine its HRR and physical

dimensions. In calculating thermal radiation, the size of the fire implies the time-averaged

size of the visible envelope.

(2) Characterize the radiative properties of the fire; that is, determine the average irradiance

of the flames (emissive power).

(3) Calculate the radiant intensity at a given location. This can be accomplished after

determining the geometry of the fire; its radiation characteristics; and the location, geometry,

and orientation of the target.Determine the HRR from Equation 5-2 or from experimental

data available in the literature.

(4) Determine the height of the pool fire.

(5) Calculate the view or configuration factor.

(6) Determine the effective emissive power of the flame.

(7) Calculate the radiative heat flux to the target.
5-19

5.9 References

American Gas Association (AGA), “LNG Safety Research Program,” Report IS 3–1. 1974.

Babrauskas, V., “Burning Rates,” Section 3, Chapter 3-1, SFPE Handbook of Fire Protection

Engineering, 2 Edition, P.J. DiNenno, Editor-in-Chief, National Fire Protection Association, nd

Quincy, Massachusetts, 1995.

Drysdale, D.D., An Introduction to Fire Dynamics, Chapter 4, “Diffusion Flames and Fire Plumes,”

2 Edition, John Wiley and Sons, New York, pp.109–158, 1998. nd

Barry, T.F., Risk-Informed, Performance-Based Industrial Fire Protection, TFBarry Publications and

Tennessee Valley Publications, Knoxville, Tennessee, 2002.

Beyler, C.L., “Fire Hazard Calculations for Large Open Hydrogen Fires,” Section 3, Chapter 1,

SFPE Handbook of Fire Protection Engineering, 3 Edition, P.J. DiNenno, Editor-in-Chief, National rd

Fire Protection Association, Quincy, Massachusetts, 2002.

EPRI TR-100370, “Fire-Induced Vulnerability Evaluation (FIVE),” Final Report, Electrical Power

Research Institute, Palo Alto, California, April 1992.

Fay, J.A., and D.H. Lewis, “Unsteady Burning of Unconfined Fuel Vapor Clouds,” Sixteenth

Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, Pennsylvania. pp.

1397–1404, 1977.

Hasegawa, K., and K. Sato, “Study on the Fireball Following Steam Explosion of n-Pentane,”

Second Symposium on Loss Prevention and Safety Promotion in the Process Industries,

Heidelberg, pp. 297–304, 1977.

Heskestad, G., “Fire Plumes,” Section 2, Chapter 2-2, SFPE Handbook of Fire Protection

Engineering, 2 Edition, P.J. DiNenno, Editor-in-Chief, National Fire Protection Association, nd

Quincy, Massachusetts, 1995.

Modak, A., “Thermal Radiation from Pool Fires,” Combustion and Flames,” Volume 29, pp.

177–192, 1977.

Nolan, D.P., Handbook of Fire and Explosion Protection Engineering Principles for Oil, Gas,

Chemical and Related Facilities, Noyes Publications, Westwood, New Jersey, 1996.

Roberts, A., “Thermal Radiation Hazards from Release of LPG Fires from Pressurized Storage,”

Fire Safety Journal, Volume 4, pp. 197–212, 1982.

SFPE Engineering Guide, “Assessing Flame Radiation to External Targets from Pool Fires,” Society

of Fire Protection Engineers (SFPE), Bethesda, Maryland, June 1999.

Shokri, M., and C.L. Beyler, “Radiation from Large Pool Fires,” SFPE Journal of Fire Protection

Engineering, Volume 1, No. 4, pp.141–150, 1989.

Thomas, P.H., “The Size of Flames from Natural Fires,” Ninth Symposium (International) on

Combustion, The Combustion Institute, Pittsburgh, pp. 844–859, 1962.
5-20

5.10 Additional Readings

Cote, A., and P. Bugbee, Principle of Fire Protection, 2 Edition National Fire Protection nd

Association, Quincy, Massachusetts, 1988.

Friedman, R., Principles of Fire Protection Chemistry and Physics, 3 Edition, National Fire rd

Protection Association, Quincy, Massachusetts, 1998.

Fire Dynamics Course Guide, Federal Emergency Management Agency (FEMA), United States Fire

Administration (USFA), National Emergency Training Center, Emmitsburg, Maryland, 1995.

Karlsson, B., and J.G. Quintiere, Enclosure Fire Dynamics, Chapter 7, “Heat Transfer in

Compartment Fires,” CRC Press LLC, New York, pp. 141–180, 1999.

Quintiere, J.G., Principles of Fire Behavior, Chapter 3, “Heat Transfer,” Delmar Publishers, Albany,

New York, pp. 47–64, 1997.
5-21

Example Problem 5-1: Radiant Heat Flux from a Pool Fire to a Target Fuel

5.11 Problems

Example Problem 5.11-1

Problem Statement

A pool fire scenario arises from a breach (leak or rupture) in a transformer. This event allows the

fuel contents of the transformer to spill and spread over the compartment floor. The compartment

is very large and has a high ceiling (e.g., typical reactor building elevation of a BWR, turbine

building open area). A pool fire ensues with a spill area of 9.0 ft on the concrete floor. Calculate 2

the flame radiant heat flux to a target (cabinet) at ground level with no wind using: a) point source

radiation model and b) solid flame radiation model. The distance between the fire source and the

target edge is assumed to be 10 ft.

Solution

Purpose:

(1) Calculate the radiant heat flux from the pool fire to the target cabinet using the point

source and solid flame radiation models.

Assumptions:

(1) The pool is circular or nearly circular.

(2) Radiation to the surroundings can be approximated as being isotropic or emanating

from a point source (valid for point source radiation model only).

(3) The correlation for solid flame radiation model is suitable for most fuels.
5-22

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 05.1_ Heat_Flux_Calculations_Wind_Free.xls

(click on Point Source and Solid Flame 1 for point source and solid flame analysis

respectively).

FDT Input Parameters: (For both spreadsheets) s

curb -Fuel Spill Area or Curb Area (A ) = 9.0 ft2

-Distance between Fire Source and Target (L) = 10 ft

-Select Fuel Type: Transformer Oil, Hydrocarbon

Results*

Radiation Model Radiant Heat Flux

 kW (Btu/ft -sec) 2

Point Source 1.45 (0.13)

Solid Flame 3.05 (0.27)

* see spreadsheet on next page
5-23

Spreadsheet Calculations

FDT : 05.1_ Heat_Flux_Calculations_Wind_Free.xls (Point Source) s

CHAPTER 5. ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET 

FUEL AT GROUND LEVEL UNDER WIND-FREE CONDITION 

POINT SOURCE RADIATION MODEL 

Version1805.0 

The fdlowilg calcdationsestimate lhe radiative heat1ux from a pool1ireto atarga fuel. 

The purpose ofthis calcdation ism estinate lhe r.adiatim nns~d from a burning fuel anayto a target 

fuel positicned some distance tom the hat ground level to detennine ifsecondiiryignitions are likEly with no wind. 

Parameters in YELLOW CELLS are Ertered bvthe User. 

Parameters in GREEN CELLS are Autcmaticallv SeJectedfrcm the DROP DOWN M ENUforthe Fuel Selected . 

.All subsequent oltput \Glues are calculated by1he spreadsheet and based on \Glues speciied in the ilput 

parameters. This spreadsheet is prote~d 3ld secure to awid errors due to a wrong envy in a cell(s). 

The chapter in the N UREG should be read before an analy;is is made. 

INPUT PARAMETERS 

Miss Buning Pate of Fuel (m") 

Effecti'W Heat of Corrbustion of Fuel (AH .... ) 

Errpirical Conmnt IW) 

Ji.!at Release Pate (Q) 

Fuel Aea or Oke .A"ea (AM) 

Dmnce betWeen Fire and 'Drget (L) 

Radiative Fr.action (1) 

OPTIONAL CALCULATION FOR GIVEN HEAT RELEASE RATE 

FALSE 

~ct" u sp~c ln &d lu~" trom RJ I T'Jp~ r.unu and Blter Your HRR :r~ ? 

THERMAL PROPERTIES OAT A 

BURNING RATE OO.TA FOR FUELS 

Miss Buning Pate ~at of Combustion Fuel 

m"(kg.tn2-sec) AH~"' (k..LC<g) 

tlkth3lol 0017 20.000 

Bhanol 0015 26.800 

BUI3ne 0078 46.700 

Benzene 0085 40.100 

~xane OD74 44.700 

~ptane 0.101 44.600 

X~ene 009 40.800 

...,. .... OD41 25.800 

Doxane 0018 26.200 

DethyBher 0085 34.200 

Benzine 0048 44.700 

Gasoline 0055 43.700 

Kerosine 0039 43.200 

Desel 0046 44.400 

JP-4 0051 43.500 

JP-5 OD54 43.000 

Transi:lnner Oil, Hyjrocarbon 0039 48.000 

561 Silicon Transfonner Auid 0005 28.100 

Fuel 01, Heavy 0035 39.700 

Dude 01 00335 42,600 

Lube Oil 0039 48.000 

D:luglas Fir Plywood 001082 10.900 

User Soecified \t.ilue Enter~lue a-.ter \t.ilue ~ ·~rr;,; {'", :: ~ ~«t'J ::""~ nu-• . ;o, "" 

900 

030 

Calt tllate 

:::'~~~nca Constant 

l4l (m t) 

100 

100 

2.7 

2.7 

19 

1.1 

1.4 

19 

5.4 

0.7 

36 

2.1 

35 

2.1 

36 

16 

0.7 

100 

1.7 

2S 

0.7 

100 

Erter\t.ilue 

I• 

0.8•~~'~' 

JJ.I~h\ 

•:•.:v 

Seled Fuel T'IJPe 

Scroll to desired fuel t}Pe then 

Click en selecti en 
5-24

E STIMA TIIIG RADIATIVE HE A TFLUX TO A TARGET FUEL 11.' -t"ro:' SFl" ~-.:> « F:~i> «t:.:>n f'Y;j , 3"' &!!len, Z~.l"~ Zi': . 

POINT SOURCE RADIATION MODEL 

q"= 01,/4 liiR:r 

\Aihere q"= incident radiative heat 1ux on the target (kVll.tnl) 

Q = pool fi"e heat release r.Jte (kVll) 

1. = radiati\@ fraction 

R =distance from center ofthe pool fire to edge oflhe target (m) 

Pod Are Diameter calculation 

A u ... = .ll0;:/4 

0= v(4A ~~t:t-) 

Vlhlere 

0= 

A """ = surface area of pool fire (m;;) 

0 =pool fire diamter (m) 

1.03 m 

Heat ~lease Rate CalcUation 

Q = m"AH,..,,(1 • "'~> A 

Vlhlere 

Q= 

Q = pool fi"e heat release r.Jte (kVll) 

m" =mass burning r.m of fuel per unit surtice area (kg.tn1-sec) 

AH .. = effecti'W heat of combustion of i.Jel (kJA<g) 

A = surUce areaofpool h (area invoi'Wd inwporizalion)(m:t) 

kP =empirical constant (m) 

0 =diameter of pool fire (diameltlr imol\@d in wporizalion, circular pool is assumed)(m) 

77152 kW 

Oistarce trcm Certer d the Fire to Edged the Target CalcUation 

R= l+DI2 

mere 

R= 

R =distance from center ofthe pool fire to edge oflhe target (m) 

l =distance between pool hand target (m) 

0 =pool fire diameter (m) 

3.56 m 

Radative !-hat Flux CalcUaticn 

q"= 01, /4 "'R ~ 

The abo'W calculations are based on principles de'Wioped in the SFPE 1-bndbook offire Protection 

&IQineerinQ, 3"' 6:1ition, 2002. 

Calcolalions are based on certain assumptions and ha'W inherent limitJtions. The results of such 

calco IRons may or may not have reason able predicti'W capabilities i:l r a gi'W n situation. and 

should only be interpreted by an infonned user. 

#lthough each calculalion in lhe spreadsheet has been verified with lhe results of hand calcola1ion, 

there is no absolute guarantee oflhe accoracyofthese calculalions. 

#fly questions, comments, concerns, and suggestions, orto report an error(s) in the spreadsheet, 

please send an email to mO@nro.govor mxs3@lrc.gov. 
5-25

FDT : 05.1_ Heat_Flux_Calculations_Wind_Free.xls (Solid Flame 1) s

CHAPTER 5. ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET 

FUEL AT GROUND LEVEL UNDER WIND-FREE CONDITION 

SOLID FLAME RADIATION MODEL 

V..-sion 1805.0 

The i:lllowing calculations estii'TI3te lhe radiative heat1ux tom a pool freto a target tieL 

The purpose ofthis calculation is to eSiimate lhe radiationtrans~d from a burning tiel anayto a arget 

fuel positioned some distance from the fire at Qround level to detennine ifsecondarviQnitions are liblvwilh no wind. 

Parameters in YELLOW CELLS are Entered bvthe User. 

Parameters in GREEN CELLS are ALiomatically Selected from the DROP DOWN M ENUforthe Fuel Selected. 

F41 suosequent output w1ues are calculated bytne spreadsheet and based on \Glues spec11ed 1ntne 1nput 

parameters. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a cell(s). 

The chapter n the NUREG should be read bebre an analysis is made. 

INPUT PARAMETERS 

Mass Burning Rate of Fuel (m") 0039 

Effectit@ ~at of Combustion of Fuel (AH ~.,•) FALSE 48000 

t:o;~ IIYo ( 

•:.1•:\1 

Empirical Constant (kp) 0.711'1 

Heat Release Rate (Q) 77152 •:•.:v 

Fuel Area or Dke ~a (A».n) 9DO 1f 

Distance between Fire and Target (l) 10DO 11 

OPDOIIAI. CALCULADOII FOR GIVE II HEAT RELEASE RA 1E ~ct" H Spulhd VIIIU&" trom Fll&l T'jp~ t.l&nu lind En~r r HRR &r~? C::::=::::J•w 

I! Cal<tl ate 

THERMAL PROPERTIES OAT A 

BURNING RATE DATA FOR FUELS 

l':fllP•nca 

Fuel Mass Burning Rate Heat of Combustion Constant Select Fuel Type 

m"(kg.tn*-sec) AH~.,, (kJo1<g) k~(m ') ~ ;tug•mWI:' 'II ~~Q a,ilf.:ag ·I Methanol 0.017 20000 100 Scroll to desired fuel type then 

Bhanol 0.015 26~00 100 Click en selection 

Butane 0.078 46.700 2.7 

Benzene 0.085 40.100 2.7 

Hexane 0.074 44,700 1.9 

Heptane 0.101 44~00 1.1 

Xylene 0.09 40~00 1.4 

.Acetone 0.041 25~00 1.9 

Dioxane 0.018 26l00 5.4 

DiethyBher 0.085 34l00 0.7 

Benzine 0.048 44,700 3.6 

Gasoline 0.055 43.700 2.1 

Kerosine 0.039 43l00 3.5 

Diesel 0.046 44,400 2.1 

JP-4 0.051 43500 3.6 

JP-5 0.054 43000 1.6 

Transimner Oil, Hy:lrocarbon 0.039 48000 0.7 

561 Silicon Transi:lnner Fllid 0.005 28.100 100 

Fuel Oil, Heavy 0.035 39.700 1.7 

Crude Oil 0.0335 42~00 2.8 

Lube Oil 0.039 48000 0.7 

Douglas Fir Plywood 0.01082 10~00 100 

User Speci6ld \1.31ue Enter Value Enter \1.31ue Enter Value 11.~1'NNY.~: $FI":f ~"¢o ('(F)"~I" rt«l:cn <:n;~~ , )' &lllcn,lOOZ, ~oe- . 
5-26

ESTIMATING RADIATIVE HEAT FLUX TO AT ARGET FUEL 

r.~ trm:,: s;::p=~-..:~o. dF~Prct('<.7J:>n~rt;~. 3" &ulcn, zoo:.~ zoo. 

S OLIO FLAME RAOLo.TLON MO OE L 

q· · EF·-o:t 

Pool Fin Ct~m$ter 0.1c u1a11on 

.:..- · 11 0

1

" 

0 • V(4A..,.P) 

li>J ~ ·~ 

·-

Em I u h$ Powu O.lc ulaUon 

'N·-~•e 

·-

Vl$'1.' Filctor 0.1CU1111IOO 

s·--

·-

q• • IICtl: ltladl'IU ~ hat11U OI1U tllg~t $Wihl ~ 

E· ~llllat.r~ powu on e poo1111 e ll.'IIIH ;t;V'V,tll) 

f ·-o:t• !JI:W T<t:tol l=*tNH I tU;J~taUI1U ll.'IIIH 

.~ ..... - Hmo: a~ea rpoo lm Qll) 

o- poo1111e dl.'llll~ 1 Qll) 

1.(+$ .... 

58 (1 41WI!:.a ~ 

E· ~llllat.re pOWH OT1U po01111 e ll.'lllle $W tll ~ 

O• di.'IIIH,IOT1UpOOITII! Qll) 

SUS kW,III :t 

;,.6-lts}t'(6·-l) " tu ((6+1) \S-1)/(6-1)\S+I)) 4.-l f'S)f(!~ 1) ')t.'ll \tA.+I)\S-1)',4.-1)\S+l))' .. 

llf!s.+ til /\f 1) )- /'!Is.; til \i..~ )'\S+fi) ,_. +.:. .• .t'S '. 1) ,.. til (t\ 1)~1) l)(S+l))' ,.. 

(•

1

-te1+ 1)CS 

(l+S) as 

2 RID 

2H.JD 

1Hf 1 ·-o:ttt+ f

1 · ... :tv) 

-o:ttt• •o ii!Oitllvt:w acto1 

f · o:~v • ve 11J t: w T<t:tol 

F· 4, ..... 111axrn 1111 v w Tacbl 

R• dl$t.'IIO? TDIII O? lteiOT!U POOI111e tHd\1? OT!U tll\l?tfll) 

H, • h.;JU OT1U poolm Tl'IIIH Qll) 

0 • po0111fe di.'IIIH' I Qll) 

Cht'IOU 11'0111 Q nter OTUl$ POOl Fin b 6:1{.1& OTUl$ Tilrg&tO.ICUIIIUOO 

R•l+0/2 

R•l+0/2 • 

Hut R$IU •& Rate O.lculaUon 

0 -~~~ ....,, :. tJM 

~•e 

a -

P, • <11$t.'IIO? TICtll 0: ltel OT1U poolm to edg~ OT1U tllg~t Qll) 

l• dttuo: l=*tNH 1 poo1111e a 1d t.119~t Qll) 

o- poo1111e dl.'llll ~' 1 Qll) 

UU111 

a - poolm hat 1e1:ase rate ;t:v·v;. 111'- 111aa b l o 119 1.'1' ortu lp; 1 11 h i m o: a~~a ;t gfhl ~~ c.. 

· ~Tf:CU e HatOTCCtll bi$1)H OTTHI ;J;J,I;g) 

.:.._,....,. IIT<t e <Ilea OTpOOITII! Gi l~a lltJOt.red II vapOIIZaOH) Qll) 

p • e111p11ta1 COI$t.'llt Qll ) 

0 • dl'IIIH' IOTpOOITII! 1$11.'111 etel ll tJOt.r~d II vapOIIZaOH, CIICI l.'llpOOI ~ <1 $1111~ (~ Qll) 

77 1.52 kW 

POOl Fin flilhl$ H&lg ht 0.1CU1111IOO ~ H,• 0.235 Q -1.02 0 

··-

S • 2 R/ O • 

• • 2H,/O • 

A • (.

1

+S1

+ 1)CS • 

' - (l..s')tzsH, •11.'1111 e h tJU QII) 

a - uat1e1:aa 1.'1' o1111e ;t;W) 

0 • 11fe di.'IIIH' I Qll) 

2.$+)$ 1(1 

U+JS 

u~s 

J.37 1 

$.$ ~ 
5-27

Ra<lative Heat Fltll< Calttllation 

The above cala..dations a-e based on prindples developed in the SFPE Handbook of Fire Prctection 

Enaineerina. 3'4 Edition, JJ02. 

Calrulatims are based on certain assumptions and have inherent limitations. The results of such 

calrulations may or may net have reasonal:je t:redictive capabilities for a gven situation, and should 

only be interpreted by an informed user . 

.AJthough esch calcUation in the spreadsheet has been verified W1h the results of hand calculation, 

there is no absolute guarantee ofthe aa:uracy of these calrulations. 

My questions, can merts, concerns, and suggestions, or to report an error( s) in the spreadsheet, 

please send an email to mdcaJlrc.aov or mxs3@nrc.aov. 
5-28

Example Problem 5-2: Radiant Heat Flux from a Burning Pallet to a Target Fuel

Example Problem 5.11-2

Problem Statement

A transient combustible fire scenario may arise from burning wood pallets (4 ft x 4 ft = 16 ft ), 2

stacked 10 ft high on the floor of a compartment with a very high ceiling. Calculate the flame

radiant heat flux to a target (safety-related cabinet) at ground level with no wind, using the point

source radiation model and the solid flame radiation model. The distance between the fire source

and the target edge (L) is assumed to be 15 ft.

Solution

Purpose:

(1) Calculate the radiant heat flux from the fire source to the target cabinet using the

point source and solid flame radiation models.

Assumptions:

(1) The fire source will be nearly circular.

(2) Radiation to the surroundings can be approximated as being isotropic or emanating

from a point source (valid for point source radiation model only).

(3) The correlation for solid flame radiation model is suitable for most fuels.
5-29

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 05.1_Heat_Flux_Calculations_Wind_Free.xls

 (click on Point Source and Solid Flame 1 for point source and solid flame

 analysis respectively)

FDT Inputs: (For both spreadsheets) s

curb -Fuel Spill Area or Curb Area (A ) = 16 ft2

-Distance between Fire Source and Target (L) = 15 ft

-Select Fuel Type: Douglas Fir Plywood

Results* 

Radiation Model Radiant Heat Flux

 kW (Btu/ft -sec) 2

Point Source 0.15 (0.01)

Solid Flame 0.45 (0.04)

*see spreadsheet on next page
5-30

Spreadsheet Calculations

FDT : 05.1_Heat_Flux_Calculations_Wind_Free.xls (Point Source) s

CHAPTER 5. ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET 

FUEL AT GROUND LEVEL UNDER WIND-FREE CONDITION 

POINT SOURCE RADIATION MODEL 

Version1805.0 

The fdlowilg calcdationsestimate lhe radiative heat1ux from a pool1ireto atarga fuel. 

The purpose ofthis calcdation ism estinate lhe r.adiatim nns~d from a burning fuel anayto a target 

fuel positicned some distance tom the hat ground level to detennine ifsecondiiryignitions are likEly with no wind. 

Parameters in YELLOW CELLS are Ertered bvthe User. 

Parameters in GREEN CELLS are Autcmaticallv SeJectedfrcm the DROP DOWN M ENUforthe Fuel Selected . 

.All subsequent oltput \Glues are calculated by1he spreadsheet and based on \Glues speciied in the ilput 

parameters. This spreadsheet is prote~d 3ld secure to awid errors due to a wrong envy in a cell(s). 

The chapter in the N UREG should be read before an analy;is is made. 

INPUT PARAMETERS 

Miss Buning Pate of Fuel (m") 

Effecti'W Heat of Corrbustion of Fuel (AH .... ) 

Errpirical Conmnt IW) 

Ji.!at Release Pate (Q) 

Fuel Aea or Oke .A"ea (AM) 

Dmnce betWeen Fire and 'Drget (L) 

Radiative Fr.action (1) 

FALSE 

1600 

030 

O:P:T:IO:N:A~L::CA::LC:U:L:A~T:IO:N::F:O R~G~IV~E~N~H~EA~T~R~E~LEA~S~E~R~A~T~E ~~~~--_j~~~~~ ~ct"U u sp~c ln ~d lu~" trom RJ I T' p~ t.1 enu and BlterYour HRR h:r~? •:•.:v 

Calttllate 

THERMAL PROPERTIES OAT A 

BURNING RATE OO.TA FOR FUELS 

Miss Buning Pate ~at of Combustion :::'~~~nca Seled Fuel T'IJPe Fuel Constant 

m"(kg.tn2-sec) AH~"' (k..LC<g) l4l (m t) 

tlkth3lol 0017 20.000 100 Scroll to desired fuel t}Pe then 

Bhanol 0015 26.800 100 Click en selecti en 

BUI3ne 0078 46.700 2.7 

Benzene 0085 40.100 2.7 

~xane OD74 44.700 19 

~ptane 0.101 44.600 1.1 

X~ene 009 40.800 1.4 

...,. .... OD41 25.800 19 

Doxane 0018 26.200 5.4 

DethyBher 0085 34.200 0.7 

Benzine 0048 44.700 36 

Gasoline 0055 43.700 2.1 

Kerosine 0039 43.200 35 

Desel 0046 44.400 2.1 

JP-4 0051 43.500 36 

JP-5 OD54 43.000 16 

Transi:lnner Oil, Hyjrocarbon 0039 48.000 0.7 

561 Silicon Transfonner Auid 0005 28.100 100 

Fuel 01, Heavy 0035 39.700 1.7 

Dude 01 00335 42,600 2S 

Lube Oil 0039 48.000 0.7 

D:luglas Fir Plywood 001082 10.900 100 

User Soecified \t.ilue Enter~lue a-.ter \t.ilue Erter\t.ilue ~ ·~rr;,; {'", :: ~ ~«c..:r ::""~ nu-• . ;o, "" 
5-31

E STIMA TIIIG RADIATIVE HE A TFLUX TO A TARGET FUEL 11.' -t"ro:' SFl" ~-.:> « F:~i> «t:.:>n f'Y;j , 3"' &!!len, Z~.l"~ Zi': . 

POINT SOURCE RADIATION MODEL 

q"= 01,/4 liiR:r 

\Aihere q"= incident radiative heat 1ux on the target (kVll.tnl) 

Q = pool fi"e heat release r.Jte (kVll) 

1. = radiati\@ fraction 

R =distance from center ofthe pool fire to edge oflhe target (m) 

Pod Are Diameter calculation 

A u ... = .ll0;:/4 

0= v(4A ~~t:t-) 

Vlhlere 

0= 

A """ = surface area of pool fire (m;;) 

0 =pool fire diamter (m) 

1.38 m 

Heat ~lease Rate CalcUation 

Q = m"AH,..,,(1 • "'~> A 

Vlhlere 

Q= 

Q = pool fi"e heat release r.Jte (kVll) 

m" =mass burning r.m of fuel per unit surtice area (kg.tn1-sec) 

AH .. = effecti'W heat of combustion of i.Jel (kJA<g) 

A = surUce areaofpool h (area invoi'Wd inwporizalion)(m:t) 

kP =empirical constant (m) 

0 =diameter of pool fire (diameltlr imol\@d in wporizalion, circular pool is assumed)(m) 

17531 kW 

Oistarce trcm Certer d the Fire to Edged the Target CalcUation 

R= l+DI2 

mere 

R= 

R =distance from center ofthe pool fire to edge oflhe target (m) 

l =distance between pool hand target (m) 

0 =pool fire diameter (m) 

526 m 

Radative !-hat Flux CalcUaticn 

q"= 01, /4 "'R ~ 

The abo'W calculations are based on principles de'Wioped in the SFPE 1-bndbook offire Protection 

&IQineerinQ, 3"' 6:1ition, 2002. 

Calcolalions are based on certain assumptions and ha'W inherent limitJtions. The results of such 

calco IRons may or may not have reason able predicti'W capabilities i:l r a gi'W n situation. and 

should only be interpreted by an infonned user. 

#lthough each calculalion in lhe spreadsheet has been verified with lhe results of hand calcola1ion, 

there is no absolute guarantee oflhe accoracyofthese calculalions. 

#fly questions, comments, concerns, and suggestions, orto report an error(s) in the spreadsheet, 

please send an email to mO@nro.govor mxs3@lrc.gov. 
5-32

FDT : 05.1_Heat_Flux_Calculations_Wind_Free.xls (Solid Flame 1) s

CHAPTER 5. ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET 

FUEL AT GROUND LEVEL UNDER WIND-FREE CONDITION 

SOLID FLAME RADIATION MODEL 

Version 19l5.0 

The i:llloo.~ilg calcolalions estii'TI3tethe radative hea flUI( frun a pool fi~e ro a target fuel. 

The p.Jrpose oflhis calcolalion is 10 estimate lhe radialion11'3nsmNd fran a b.Jming tiel anayto aarget 

fuel postimed some distalce tom the fire at Qround le'WI to detEfTTline if seconmrv i!Jlitions a~e lkelvwith no wind. 

ParamEters in YELLOWCELLS are Enteredbvthe User. 

ParamEters in GREEN CELLS are Autormti callv Selected from the 0 RO P DOWN MENU fer the Fuel SEI ected . 

.All subsequert oUiput \Glues are calculated by1he sp-eadshec and based on \Glues speciied in the irput 

pai'3Tleters. This spreadsheet is p~cted aM secure to awid e~rors due ro a wrmg entrvin a cell(s). 

The chaj:terin1he NUREG stould be read before an an-'ysisis made. 

INPUT PARAMETERS 

tvbss Bumirg Pate of Fuel (m') 0.01082 1;-J ,'h\ ( 

Effective ~at of Ccmbustion of Fuel (laH ~ .. •) 

Erroirical Ccnmnt(kll) 

~at ~lease Pate (Q) 

Fuei.A"ea or Dke .A"ea (AM) 

Dstanoe between Fi~e ald Target (l) 

OPTIONAL CALCULATION FOR GIVEN HEAT RELEASE RATE 

FALSE 

S& ~c &r p~C I11 ~d lu ~" trOifl f\t:l T' p~ f.1 enu and EnUr YOU' HRR IUr ? 

THERMAL PROPERTIES OAT A 

BURNING RATE DATA FOR FUELS 

Fuel tubss Burring Rae Heat of Comb.Jslion 

m" (kg.tn ·-sec) AH.• (1<-"<g) 

==~11111~0~0: I:J,.;oJ 

175.31 " I!N 

1600 "' 

15DO 11 

c:===::J•t!N 

l':f'lpnca 

Cor613nt Sele:t Fuel Type 

kP(m ') l:tt> Ar A 11a gaQ 1-1 

Mnhanol 0017 lO,OOO 100 Scroll to desiredfuel type thE'fl 

Bhanol 0015 26,1100 100 Click en sel ecti en 

Butane 0078 46,100 2.7 

Benzene 0085 41,100 2.7 

Hexalle OD74 44,700 1.9 

Heptane 0.101 44,1110 1.1 X~ene 009 41,1100 1.4 

A>etone OD41 25,1100 1.9 

Doxalle 0018 l6,l00 5.4 

DethyBher 0085 34,l00 0.7 

Benzine 0048 44,700 3.6 

Gasoline 0055 43,100 2.1 

Kerosine 0039 43,l00 3.5 

Desel 0046 44,4)0 2.1 J~4 0051 43,6110 3.6 

J~5 OD54 43,000 1.6 

Tr3lsi:lnner Oil, ~rocarbm 0039 43,000 0.7 

561 Siicon Transfumer Auid 0005 lS,IOO 100 

Fuel Oil, Heavy 0035 311,100 1.7 

Dude Oil 00335 42,1100 2.8 

Lube 01 0039 43,000 0.7 

Cbuglas Fir Plyuood 001082 10,100 100 

User ~eciied \klle Enter\kiiR 8"4Er ~ue Enter~lue 

l\t1Ht~: = ~ "'"" ~ ,¢n ~l"'«!l ·~ e;m on. . ~ 
5-33

ESTIMATING RADIATIVE HEAT FLUX TO AT ARGET FUEL 

r.~ trm:,: s;::p=~-..:~o. dF~Prct('<.7J:>n~rt;~. 3" &ulcn, zoo:.~ zoo. 

S OLIO FLAME RAOLo.TLON MO OE L 

q· · EF·-o:t 

Pool Fin Ct~m$ter 0.1c u1a11on 

.:..- · 11 0

1

" 

0 • V(4A..,.P) 

li>J ~ ·~ 

·-

Em I u h$ Powu O.lc ulaUon 

'N·-~•e 

·-

Vl$'1.' Filctor 0.1CU1111IOO 

s·--

·-

q• • IICtl: ltladl'IU ~ hat11U OI1U tllg~t $Wihl ~ 

E· ~mlat.r~ powu on e poo1111 e ll.'IIIH ;t;V'V,tll) 

f ·-o:t• !JI:W T<t:tol l=*tNH I tU;J~taUI1U ll.'IIIH 

.~ ..... - Hmo: a~ea rpoo lm Qll) 

o- poo1111e dl.'llll~ 1 Qll) 

1.$$ .... 

58 (1 41WI!:.a ~ 

E· ~mlat.re pOWH OT1U po01111 e ll.'lllle $W tll ~ 

O• di.'IIIH,IOT1UpOOITII! Qll) 

SUI kW,III :t 

;,.6-lts}t'(6·-l) " tu ((6+1) \S-1)/(6-1)\S+I)) 4.-l f'S)f(!~ 1) ')t.'ll \tA.+I)\S-1)',4.-1)\S+I))' .. 

llf!S.. til /\f 1) )- /'!Is.; til \i..~ )'\S+fi) ,_. +.:. .• .t'S '. 1) ,.. til (t\ 1)~1) I)(S+I))' ,.. 

(•

1

-te1+ 1)CS 

(l+S) as 

2 RID 

2H.JD 

1Hf 1 ·-o:ttt+ f

1 · ... :rv) 

-o:ttt• •o ii!Oitllvt:w acto1 

f · o:~v • ve 11J t: w T<t:tol 

F· 4, ..... maxlll 1111 v w Tacbl 

R• dl$t.'II O? TDIII O? lteiOT!U POOI111e tHd\1? OT!U tll\l? tfll) 

H, • h.;JU OT1U poolm Tl'IIIH Qll) 

0 • po0111fe di.'IIIH' I Qll) 

Cht'IOU 11'0111 Q nter OTUl$ POOl Fin b 6:1{.1& OTUl$ Tilrg&tO.ICUIIIUOO 

R•l+0/2 

R•l+0/2 • 

Hut R$IU •& Rate O.lculaUon 

0 ·m ....,, :. tJM 

~•e 

a -

P, • <11$t.'II O? TICtll 0: ltel OT1U poolm to edg~ OT1U tllg~t Qll) 

l• dttuo: l=*tNH 1 poo1111e a 1d t.119~t Qll) 

o- poo1111e dl.'llll ~' 1 Qll) 

S.HO Ill 

a - poolm hat 1e1:ase rate ;t:v·v;. m·- maa b l o 119 1.'1' ortu lp; 1 11 h i m o: a~~a ;t gfhl ~~ c.. 

· ~Tf:CU e HatOTCCtll bi$1)H OTTHI ;J;JJ;g) 

.:.._,....,. IIT<t e <Ilea OTpOOITII! Gi l~a lltJOt.red II vapOIIZaOH) Qll) 

p • emp11ta1 COI$t.'llt Qll ) 

0 • dl'IIIH' IOTpOOITII! 1$11.'111 etel ll tJOt.r~d II vapOIIZaOH, CIICI l.'llpOOI ~ <1 $1111~ (~ Qll) 

175.31 kW 

POOl Fin flilhl$ H&lg ht 0.1CU1111IOO ~ H,• 0.235 Q -1.02 0 

··-

S • 2 R/ O • 

• • 2H,/O • 

A • (.

1

+S1+ 1)CS • 

' - (l..s')tzsH, •11.'1111 e h tJU QII) 

a - uat1e1:aa 1.'1' o1111e ;t;W) 

0 • 11fe di.'IIIH' I Qll) 

0.45$ .... 

7 .SJl 

O.SSS 

3.317 

U$3 
5-34

Ra<lative Heat Flu)( Calttllation 

The above calrulations sre based on prindples developed in the SFPE Handbook of Fire Prctection 

Enaineerina. 3'4 Edition, JJ02. 

Calrulatims are based on certain assumptions and have inherent limitations. The results of such 

calrulations may or may nct have reasonal1e p-edictive capabilities for a gven situation, and should 

only be interpreted by an informed user . 

.AJthough ea:h calcUation in the spreadsheet has been veri1ied W1h the results of hand calculation, 

there is no absolute guarantee of the aa:uracy of these calrulations. 

My questions, can merts, concerns, and suggestions, or to report an error( s) in the spreadsheet, 

please send an email to nxiCGirlrc.aov or mxs3@nrc.aov. 
5-35

Example Problem 5-3: Radiant Heat Flux from a Burning Cable Tray to a Target Fuel

Example Problem 5.11-3

Problem Statement

A fire scenario may arise from a horizontal cable tray burning in a very large compartment. The

cables in the tray are IEEE-383 unqualified and made of PE/PVC insulation material (assume that

the exposed area of the cable is 20 ft ). Another safety-related cable tray also filled with IEEE-383 2

unqualified made of PE/PVC insulation material is located at a radial distance (L) of 9 ft from the

fire source. Calculate the flame radiant heat flux to a target (safety-related cable tray) using the

point source radiation model and solid flame radiation model. Is this heat flux sufficient to ignite the

cable tray?

Solution

Purpose:

(1) Calculate the radiant heat flux from the burning cable tray to the target cable tray

using the point source and solid flame radiation models.

(2) Determine if the heat flux is sufficient to ignite the cable tray.

Assumptions:

(1) The fire source will be nearly circular.

(2) Radiation to the surroundings can be approximated as being isotropic or emanating

from a point source (point source radiation model only).

(3) The correlation for solid flame radiation model is suitable for most fuels.
5-36

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 05.1_Heat_Flux_Calculations_Wind_Free.xls

 (click on Point Source and Solid Flame 1 for point source and solid flame analysis,

respectively).

FDT Inputs: (For both spreadsheets) s

-Mass Burning Rate of Fuel = 0.0044 kg/m -sec 2

c,eff -Effective Heat of Combustion of Fuel ( H ) = 25,100 kJ/kg

-Empirical Constant (k$) = 100 m (use this if actual value is unknown) -1

curb -Fuel Spill Area or Curb Area (A ) = 20 ft2

-Distance between Fire Source and Target (L) = 9 ft

Note: Since the insulation material (PE/PVC) is not available in the thermal

properties data of the spreadsheet, we have to input the mass burning rate and

effective heat of combustion in the spreadsheet. Values of cable materials

properties are available in Table 3-4. Select User-Specified Value, and enter the

respective values.

Results*

Radiation Model Radiant Heat Flux

 kW (Btu/ft -sec) 2

Point Source 0.4 (0.03)

Solid Flame 1.1 (0.10)

*see spreadsheet on next page
5-37

Spreadsheet Calculations

FDT : 05.1_Heat_Flux_Calculations_Wind_Free.xls (Point Source) s

CHAPTER 5. ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET 

FUEL AT GROUND LEVEL UNDER WIND-FREE CONDITION 

POINT SOURCE RADIATION MODEL 

Version1805.0 

The fdlowilg calcdationsestimate lhe radiative heat1ux from a pool1ireto atarga fuel. 

The purpose ofthis calcdation ism estinate lhe r.adiatim nns~d from a burning fuel anayto a target 

fuel positicned some distance tom the hat ground level to detennine ifsecondiiryignitions are likEly with no wind. 

Parameters in YELLOW CELLS are Ertered bvthe User. 

Parameters in GREEN CELLS are Autcmaticallv SeJectedfrcm the DROP DOWN M ENUforthe Fuel Selected . 

.All subsequent oltput \Glues are calculated by1he spreadsheet and based on \Glues speciied in the ilput 

parameters. This spreadsheet is prote~d 3ld secure to awid errors due to a wrong envy in a cell(s). 

The chapter in the N UREG should be read before an analy;is is made. 

INPUT PARAMETERS 

Miss Buning Pate of Fuel (m") OD044 t: 

Effecti'W Heat of Corrbustion of Fuel (AH .... ) FALSE 25100 •: 

Errpirical Conmnt IW) 100 

Ji.!at Release Pate (Q) 20520 t; 

Fuel Aea or Oke .A"ea (AM) 20DO 

Dmnce betWeen Fire and 'Drget (L) 9DO ,, 

Radiative Fr.action (1) 030 

O:P:T:10:N:A~L::CA::LC:U:L:A~T:10:N::F:O~R~G~1V~E~N~H~EA~T~R~E~LEA~S~E~R~A~T~E~~~~~--_j~~~~~ hl~c u p~c ln &d lu~" trom RJ I T'Jp~ r.unu and BlterYour HRR ~? •:•.:v 

Calt tllate 

THERMAL PROPERT1ES OAT A 

BURNING RATE OO.TA FOR FUELS 

;;;. Ill 

Miss Buning Pate ~at of Combustion :::'~~~nca Seled Fuel T'IJPe Fuel Constant 

m"(kg.tn2-sec) AH~"' (k..LC<g) l4l (m t) 

tlkth3lol OD17 20.000 100 Scroll to desired fuel t}Pe then 

Bhanol OD15 26.800 100 Click en selecti en 

BUI3ne OD78 46.700 2.7 

Benzene OD85 40.100 2.7 

~xane OD74 44.700 19 

~ptane 0.101 44.600 1.1 

X~ene OD9 40.800 1.4 

...,. .... OD41 25.800 19 

Doxane OD18 26.200 5.4 

DethyBher OD85 34.200 0.7 

Benzine OD48 44.700 36 

Gasoline OD55 43.700 2.1 

Kerosine OD39 43.200 35 

Desel OD46 44.400 2.1 

JP-4 OD51 43.500 36 

JP-5 OD54 43.000 16 

Transi:lnner Oil, Hyjrocarbon OD39 48.000 0.7 

561 Silicon Transfonner Auid OD05 28.100 100 

Fuel 01, Heavy OD35 39.700 1.7 

Dude 01 OD335 42,600 2S 

Lube Oil OD39 48.000 0.7 

D:luglas Fir Plywood OD1082 10.900 100 

User Soecified \t.ilue Enter~lue a-.ter \t.ilue Erter\t.ilue ~ ·~rr;,; {'", :: ~ ~«t'J ::""~ nu-• . ;o, "" 
5-38

E STIMA TIIIG RADIATIVE HE A TFLUX TO A TARGET FUEL 11.' -t"ro:' SFl" ~-.:> « F:~i> «t:.:>n f'Y;j , 3"' &!!len, Z~.l"~ Zi': . 

POINT SOURCE RADIATION MODEL 

q"= 01,/4 liiR:r 

\Aihere q"= incident radiative heat 1ux on the target (kVll.tnl) 

Q = pool fi"e heat release r.Jte (kVll) 

1. = radiati\@ fraction 

R =distance from center ofthe pool fire to edge oflhe target (m) 

Pod Are Diameter calculation 

A u ... = .ll0;:/4 

0= v(4A ~~t:t-) 

Vlhlere 

0= 

A """ = surface area of pool fire (m;;) 

0 =pool fire diamter (m) 

1.54 m 

Heat ~lease Rate CalcUation 

Q = m"AH,..,,(1 • "'~> A 

Vlhlere 

Q= 

Q = pool fi"e heat release r.Jte (kVll) 

m" =mass burning r.m of fuel per unit surtice area (kg.tn1-sec) 

AH .. = effecti'W heat of combustion of i.Jel (kJA<g) 

A = surUce areaofpool h (area invoi'Wd inwporizalion)(m:t) 

kP =empirical constant (m) 

0 =diameter of pool fire (diameltlr imol\@d in wporizalion, circular pool is assumed)(m) 

20520 kW 

Oistarce trcm Certer d the Fire to Edged the Target CalcUation 

R= l+DI2 

mere 

R= 

R =distance from center ofthe pool fire to edge oflhe target (m) 

l =distance between pool hand target (m) 

0 =pool fire diameter (m) 

3.51 m 

Radative !-hat Flux CalcUaticn 

q"= 01, /4 "'R ~ 

The abo'W calculations are based on principles de'Wioped in the SFPE 1-bndbook offire Protection 

&IQineerinQ, 3"' 6:1ition, 2002. 

Calcolalions are based on certain assumptions and ha'W inherent limitJtions. The results of such 

calco IRons may or may not have reason able predicti'W capabilities i:l r a gi'W n situation. and 

should only be interpreted by an infonned user. 

#lthough each calculalion in lhe spreadsheet has been verified with lhe results of hand calcola1ion, 

there is no absolute guarantee oflhe accoracyofthese calculalions. 

#fly questions, comments, concerns, and suggestions, orto report an error(s) in the spreadsheet, 

please send an email to mO@nro.govor mxs3@lrc.gov. 
5-39

FDT : 05.1_Heat_Flux_Calculations_Wind_Free.xls (Solid Flame 1) s

CHAPTER 5. ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET 

FUEL AT GROUND LEVEL UNDER WIND-FREE CONDITION 

SOLID FLAME RADIATION MODEL 

Version 19l5.0 

The i:llloo.~ilg calcolalions estii'TI3tethe radative hea flUI( frun a pool fi~e ro a target fuel. 

The p.Jrpose oflhis calcolalion is 10 estimate lhe radialion11'3nsmNd fran a b.Jming tiel anayto aarget 

fuel postimed some distalce tom the fire at Qround le'WI to detEfTTline if seconmrv i!Jlitions a~e lkelvwith no wind. 

ParamEters in YELLOWCELLS are Enteredbvthe User. 

ParamEters in GREEN CELLS are Autormti callv Selected from the 0 RO P DOWN MENU fer the Fuel SEI ected . 

.All subsequert oUiput \Glues are calculated by1he sp-eadshec and based on \Glues speciied in the irput 

pai'3Tleters. This spreadsheet is p~cted aM secure to awid e~rors due ro a wrmg entrvin a cell(s). 

The chaj:terin1he NUREG stould be read before an an-'ysisis made. 

INPUT PARAMETERS 

tvbss Bumirg Pate of Fuel (m') OD0441:-J ,'h., c 

Effective ~at of Ccmbustion of Fuel (laH ~ .. •) 

Erroirical Ccnmnt(kll) 

~at ~lease Pate (Q) 

Fuei.A"ea or Dke .A"ea (AM) 

Dstanoe between Fi~e ald Target (l) 

OPTIONAL CALCULATION FOR GIVEN HEAT RELEASE RATE 

FALSE 

S& ~c &r p~C I11 ~d lu ~" trOifl f\t:l T' p~ f.1 enu and EnUr YOU' HRR IUr ? 

THERMAL PROPERTIES OAT A 

BURNING RATE DATA FOR FUELS 

Fuel tubss Burring Rae Heat of Comb.Jslion 

==~25~1~0~0: I:J,.;oJ 

1026D2t" !N 

10000 "' 

9DO 11 

c:===::J•t!N 

l':f'lpnca 

Cor613nt Sele:t Fuel Type 

.!:9~~'~ .. 

Z.7•:Um 

m" (kg.tn ·-sec) AH.• (1<-"<g) kP(m ') lJJur S:lj! d11t d .. a lut 1-1 

Mnhanol 0017 20,000 100 Scroll to desiredfuel type thE'fl 

Bhanol 0015 26,1100 100 Click en sel ecti en 

Butane 0078 46,700 2.7 

Benzene 0085 41,100 2.7 

Hexalle OD74 44,700 1.9 

Heptane 0.101 44,1110 1.1 X~ene 009 41,1100 1.4 

A>etone OD41 25,1100 1.9 

Doxalle 0018 26,200 5.4 

DethyBher 0085 34,200 0.7 

Benzine 0048 44,700 3.6 

Gasoline 0055 43,700 2.1 

Kerosine 0039 43,200 3.5 

Desel 0046 44,4)0 2.1 J~4 0051 43,6110 3.6 

J~5 OD54 43,000 1.6 

Tr3lsi:lnner Oil, ~rocarbm 0039 43,000 0.7 

561 Siicon Transfumer Auid 0005 26,100 100 

Fuel Oil, Heavy 0035 311,700 1.7 

Dude Oil 00335 42,1100 2.8 

Lube 01 0039 43,000 0.7 

Cbuglas Fir Plyuood 001082 10,100 100 

User ~eciied \klle Enter\kiiR 8"4Er ~ue Enter~lue 

l\t1Ht~: = ~ "'"" ~ ,¢n ~l"'«!l ·~ e;m on, l:tlZ, ~ 
5-40

ESTIMATING RADIATIVE HEAT FLUX TO AT ARGET FUEL 

r.~ trm:,: s;::p=~-..:~o. dF~Prct('<.7J:>n~rt;~. 3" &ulcn, zoo:.~ zoo. 

S OLIO FLAME RAOLo.TLON MO OE L 

q· · EF·-o:t 

Pool Fin Ct~m$ter 0.1c u1a11on 

.:..- · 11 0

1

" 

0 • V(4A..,.P) 

li>J ~ ·~ 

·-

Em I u h$ Powu O.lc ulaUon 

'N·-~•e 

·-

Vl$'1.' Filctor 0.1CU1111IOO 

s·--

·-

q• • IICtl: ltladl'IU ~ hat11U OI1U tllg~t $Wihl ~ 

E· ~llllat.r~ powu on e poo1111 e ll.'IIIH ;t;V'V,tll) 

f ·-o:t• !JI:W T<t:tol l=*tNH I tU;J~taUI1U ll.'IIIH 

.~ ..... - Hmo: a~ea rpoo lm Qll) 

o- poo1111e dl.'llll~ 1 Qll) 

$.Lilli 

58 (1 41WI!:.a ~ 

E· ~llllat.re pOWH OT1U po01111 e ll.'lllle $W tll ~ 

O• di.'IIIH,IOT1UpOOITII! Qll) 

H.U kW,III :t 

;,.6-lts}t'(6·-l) " tu ((6+1) \S-1)/(6-1)\S+I)) 4.-l f'S)f(!~ 1) ')t.'ll \tA.+I)\S-1)',4.-1)\S+l))' .. 

llf!S.. til /\f 1) )- /'!Is.; til \i..~ )'\S+fi) ,_. +.:. .• .t'S '. 1) ,.. til (t\ 1)~1) l)(S+l))' ,.. 

(•

1

-te1+ 1)CS 

(l+S) as 

2 RID 

2H.JD 

1Hf 1 ·-o:ttt+ f

1 · ... :rv) 

-o:ttt• •o ii!Oitllvt:w acto1 

f · o:~v • ve 11J t: w T<t:tol 

F· 4, ..... 111axrn 1111 v w Tacbl 

R• dl$t.'II O? TDIII O? lteiOT!U POOI111e tHd\1? OT!U tll\l?tfll) 

H, • h.;JU OT1U poolm Tl'IIIH Qll) 

0 • po0111fe di.'IIIH' I Qll) 

Cht'IOU 11'0111 Q nter OTUl$ POOl Fin b 6:1{.1& OTUl$ Tilrg&tO.ICUIIIUOO 

R•l+0/2 

R•l+0/2 • 

Hut R$IU •& Rate O.lculaUon 

0 -~~~ ....,, :. tJM 

~•e 

a -

P, • <11$t.'II O? TICtll 0: ltel OT1U poolm to edg~ OT1U tllg~t Qll) 

l• dttuo: l=*tNH 1 poo1111e a 1d t.119~t Qll) 

o- poo1111e dl.'llll ~' 1 Qll) 

UU111 

a - poolm hat 1e1:ase rate ;t:v·v;. 111'- 111aa b l o 119 1.'1' ortu lp; 1 11 h i m o: a~~a ;t gfhl ~~ c.. 

· ~Tf:CU e HatOTCCtll bi$1)H OTTHI ;J;JJ;g) 

.:.._,....,. IIT<t e <Ilea OTpOOITII! Gi l~a lltJOt.red II vapOIIZaOH) Qll) 

p • e111p11ta1 COI$t.'llt Qll ) 

0 • dl'IIIH' IOTpOOITII! 1$11.'111 etel ll tJOt.r~d II vapOIIZaOH, CIICI l.'llpOOI ~ <1 $1111~ (~ Qll) 

102U+2 kW 

POOl Fin flilhl$ H&lg ht 0.1CU1111IOO ~ H,• 0.235 Q -1.02 0 

··-

S • 2 R/ O • 

• • 2H,/O • 

A • (.

1

+S1

+ 1)CS • 

' - (l..s')tzsH, •11.'1111 e h tJU QII) 

a - uat1e1:aa 1.'1' o1111e ;t;W) 

0 • 11fe di.'IIIH' I Qll) 

(1.2$5 .... 

2.$35 

0.14$ 

uu 

1.430 
5-41

Ra<lative Heat Flu)( Calttllation 

The above calculations a-e based on prindples developed in the SFPE Handbook of Fire Prctection 

Enaineerina. 3'4 Edition, JJ02. 

Calculatims are based on certain assumptions and have inherent limitations. The results of such 

calculations may or may net have reasonal:je t:redictive capabilities for a gven situation, and should 

only be interpreted by an informed user . 

.AJthough ea:h calcUation in the spreadsheet has been veri1ied W1h the results of hand calculation, 

there is no absolute guarantee of the aa:uracy of these calculations. 

My questions, can merts, concerns, and suggestions, or to report an error( s) in the spreadsheet, 

please send an email to nxiCGirlrc.aov or mxs3@nrc.aov. 
5-42

Example Problem 5-4: Radiant Heat Flux from a Pool Fire to a Vertical Target Fuel

Example Problem 5.11-4

Problem Statement

A pool fire scenario may arise from a leak in a pump. This event allows the lubricating oil to spill

and spread over the compartment floor. A pool fire ensues with a spill of 9.6 ft is considered in a 2

compartment with a concrete floor. The distance (L) between the pool fire and the target edge is

assumed to be 10 ft. Calculate the flame radiant heat flux to a vertical target (safety-related) 8 ft

high above the floor with no wind, using the solid flame radiation model. If the vertical target

contains IEEE-383 unqualified cables, could there be cable failure in this fire scenario?

Solution

Purpose:

(1) Calculate the radiant heat flux from the pool fire to the vertical target using the solid

flame radiation model.

(2) Determine if the IEEE-383 unqualified cables are damaged.

Assumptions:

(1) The fire source will be nearly circular.

(2) The correlation for solid flame radiation model is suitable for most fuels.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 05.1_Heat_Flux_Calculations_Wind_Free.xls (click on Solid Flame 2)

FDT Inputs: s

curb -Fuel Spill Area or Curb Area (A ) = 9.6 ft2

-Distance between Fire Source and Target (L) = 10 ft

1 f1

-Vertical Distance of Target from Ground (H = H ) = 8 ft

-Select Fuel Type: Lube Oil

Results*

Radiation Model Radiant Heat Flux

 kW (Btu/ft -sec) 2

Cable Failure

Solid Flame 3.0 (0.26) No 

*see spreadsheet on next page
5-43

Spreadsheet Calculations

FDT : 05.1_Heat_Flux_Calculations_Wind_Free.xls (Solid Flame 2) s

CHAPTER 5. ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET 

FUEL ABO\£ GROUND LEVEL UNDER IMND-FREE CONDITION 

SOLID FLAME RADIATION MODEL 

Version 1805.0 

Th Dt)WIIg cat:U.'IO,_$ thl<l' ~ l<t:ll.1tl1~ hat IIU ROlli pOOITU b a tllif.tRH 

Th p1 ~ orut a• • 1.10H ~ b u 011a' !U l.'ldhOH 1Jaumltt~d 11"0111 a bm • g tul anar b a tug~t 

IU lpoUOHHI $CttH dttUCHICtll 1U 111! ab ~ gDU d I:!J tod~'PII ~ U~ Hd<IIV .;JUtbU all? II ~ I{WU 10 Wild . 

Plll'\'lm~ten ln EllOWCEll SU~ En~r~dbj' Ul~ UtH . 

Plll'\'llll~ten ln GREEII CEllS ar~ AUbDIIIUCIIII\' $$1$C,dtrom 1h$ DROP 00\Aifl t.1EIIU forth$ f\1$1 h i$CUd . 

. :..I$ II>6$(IIUtOI1HttJ<tiH$ <ue cal l h'd ~ $p1Md, .Ht<Ud baad 0 1 V<IIH$ $I=*Crn.d II ~ llplt 

para11H~ · n 1$ $p1Md> •Ht 1$ protected <Ud $$CI I$ to <WJOI:I $110" \IH b a WDi ge 11t{ II ace II('). 

Th C'<ll)' r• U $ IIUREG $ •0 11:1 be IHd bU01e <U <11<11/$1$ ~mad! . 

INPUT PARAMETERS 

.:.:;::;.:;:.:..:;,l;ll~l.l; .. ~.:..~.~l~l9~.: .. ~.~ .• ~.~.:~1 ,:.~~~~~--------~~~~~~~~~io~.~3~9 h!,'hl '•i t ( 

E11'ectm HMtOTCCtllbU1m ff~ ~ I l:. ,,..~ f.:..LSE ,0000 t:.M:>J 

EIII PU "tut;J P) 0.7 Ill 

~atR~ l:aH Rate Q) 8' 1.15 t!N 

fHI.:.Jea iDt;~AF.a ''- > 9.60 11 ' 

Dtt.1•o: b~tN~u file a •d Talif.t(l) 10.00 11 

W rttal 0 1$t.'l•o: OTTalif.tTICtll GIOI Ul (H • H, ) 8.00 II 

OPTIONAL CALCULATION FOR GIVEN HEAT RELEASE RATE Ctltot"ll "r Ci>Uih4 Vllh"" fr\1111 Flltl Ti'l>t l.ltnlllln4 81-r Your N RR l"rt t 

~~•w Calculae 

THERMAL PROPERTIES DATA 

BURIIIIIG RATE DATA FOR FUELS 

fHI l.la " 6 m 119 Ra~ ~at III 1 Bllp lltaiCo utl•t Select Fuel Type ..... ;t:glll ~~c.. !:.H, ... , g~ I:IS •Ill . • il 

0,$911\' 

, ..... 

t.1 l 0.017 20.000 100 Scroll to d ~ r~ d ru~ 1 t,• p~ 1l~ n 

fUa •o l 0.0 IS 26.800 100 Click on t $I$C1Ion 

Slt.'IH 0.078 , 5,700 2.7 

su~ ~ 0.085 ,0,100 2.7 

na ~ O.OH U ,700 .. ~ptiH 0 .101 U .600 1.1 

~!H o•• '0.800 ... :..o: tn~ 0.041 25.800 .. o• ~ 0.018 26200 S.l 

OI:Q EU ~I 0.085 3'2 00 0.7 SUZII ~ o ... U ,700 3.6 

a. ll& ~ 0.055 ,3,700 2.1 

0$ 11 ~ o•» '32 00 3.5 01: ~ I o•IS 'uoo 2.1 ,_, 0.05 1 '3.500 3.6 ... 0.05' '3.000 .. lr Ia Wb Pll ~I 0 ll HvtiiOC<I b O I o•» ' 6.000 0.7 -6 1 S llbOI TlaU PII~ I fll.:l 0.005 28.100 100 

fH lOll, ~<I\IV 0.0~ 39,700 1.7 

::no; 0 11 0.0335 ' 2.600 2.8 

lll=* 0 I o•» '0.000 0.7 

OOI(ji.U fll P\'WOCd 0.01082 10,900 100 ~1 M!d ~ Eitel ll ~ El' IV <tit ~ El' IVa It ~ 

- - , 

j 
5-44

ESTIMATING RADIATIVE HEAT FLU X TO AT ARGET FUEL ~'tt«12 s.-?=H.TdT:o.'\ ('(F:~~«.rbn~ :;: • &Ill en !"~ ): ~ 

SOLID Fl.A ME RADIATION M DDEL 

<( • Ef ..,. 

Pool Fir~ thm~~r 0l cu a1 n 

.:._. - 11 u 

0-!J (4/'..,.,/J) 

'lV hl~ 

·-

Bll ~ Power CIICUI1110n 

E• 58 (10"""" ) 

\t\lhre 

·-\II&'A' F.letor OllculaUon 

F ..,.., • 

F . .,.u• 

·' -.'v - ,_ 

s1 -

1, -

F . .,..,• 

q• • IICt:IUtla<II.'IUJ& Hatlltx oa 1U tlr.l&t i);V'V,III_.) 

E• &hl~ 11& pcrN&I011U pooiTU 11.'1111& +;!/VAll') 

f . ...;• VI:W T<t:tol b&t,o.H a t.'llg? taadU& IL.'IIII& 

,:.,.,.., • H lf<t:.? aJ&a OTpOOI111e (II) 

o- poolm <11.'1111' 1 (II) 

U+7 m 

E• &hl~ 11& pcrN&I011U pooiTU 1\.'1111& •:\t\1.111 ') 

O• di.'WtH~I 011U poOITU II) 

$UJ i);V\1/hl} 

1/(:'0)I:n (lh '\0 .. ·1) ' "').(1, f.'O)I~ ~ 1;.'\0t I))."• A ll f.'O;.\ _.·l)."l:in i(A • IXC>I)r.;.\ ·IXOt I)) . .,. 

O)I:in (h)(d ·l) "').(1\.f.'Oll~ ~ 1;.'\0t I)) "• A.I\.f.'0 ;.\,' ·1) "&:n «A.• IXC>I)r.;.\.-- IXOt I)) " 

<• ' ..S .. + I)CS 

( . ... ..S .. +I)CS 

(1<f€:'j12S 

2P.ID 

2H,/D 

~Jo 

F "'·r +f 

·n- btl &f1) w tlcbl 

P.•dttuo: , , , ... cutuoTU& poo1111e tHdg; ~ tu;,~t ll) 

H, • ~ •JU OT1U poOITU IL.'IIM II) 

o- poolm 11.'1111 ~~~ ~~) 

Ch ttnu trom etnt.roTtllt Pool flrt to EdgtoT1lt T3rgttC11cul31on 

R•l+Ot2 

H&at R~ ~ll l& Rllt~ OliCUIIIUOn 

a • hi ·~ , .. (1 ~ •• ) .:..,... .. 

'lVhle 

a -

P, • l>tU ~ TIC411 U~I OTIU p001111e b ~dg! TU ~ tllg!t ll) 

L• d~ tno: l:.e tN~u poo1111e <Ud t.1rg;t {II) 

o- poolm 11.'1111 ~~~ ~~) 

$.$$1 hi 

Q • poo111re hat!? l:aH 1.'1~ i!:\lV) 

hi" •Ill <I$$ bU.I19 lab T1Ui p~l UlhUT<t:.: <II: <I t; gihl ~~¢.1 

• ll'ectu~ ~at cctllbn1m oTm 1 t;J.tg) 

.:.. .... "• Hmo: a•ea oTpool111 e G~rea lu tolm l" "'" )OIIZa1m) ~~ ) 

t p- ~hlplr• l co"tut ~~ ) 

0 • di.'WII~~ 10TPGOI111 e (tlbiii ~~I II !J IJHI ,_ !J<II» Italm .ClCI I.'IIPOOI t <ISHIII ~d) fll) 

Ul.IS tv·v 

Pool Fir~ Flllm~ lll O'I CU IIU O 

H,• 23s ·~ -1 .02 o 

'Nhre H• •11.'1111 ~ h tl" II) 

H,• 

S• 2RID • 

• • 2H, 10 • 

• .. - ~JoA • (. _.+S"'+I)tZS • 

a - hatr~l:aa , .. , oTIIIe t:'N) 

O•TII! di.'WII~~I II) 

2(H.-H,)ID • 

2.$$3 hi 

S.72 1 

J.S?'S 
5-45

Radiati-.e Hect Flux Calculction 

The above calculations are based on principles developed in the SFPE Handbod< of Fire Protection 

Engineering, 3f4 Edition, 2002. 

Calculations are based on certdin assumptions and have inherent limitations. The results of such 

calculations may or may not have reasonable predictive capabilities for a given situation, and should 

only be interpreted by an informed user. 

Anhough each calculation in the spreadsheet has been veri1ied with the results of hand calculation, 

there is no absolute guarantee of the accuracy of these calculations. 

Any questions. comments, concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to rod@nrc.gov or rro<:s3@nrc.gov. 
5-46

Example Problem 5-5: Radiant Heat Flux from a Burning Pallet to a Vertical Target Fuel

Example Problem 5.11-5

Problem Statement

A transient combustible fire scenario may arise from burning wood pallets (4 ft x 4 ft = 16 ft ), 2

stacked 14 ft high on the floor of a compartment. Calculate the flame radiant heat flux from

exposure fire to a vertical target (safety-related electrical junction box) located 8 ft high above the

floor, with no wind, using the solid flame radiation model. The distance (L) between the transient

fire and the target edge is assumed to be 15 ft.

Solution

Purpose:

(1) Calculate the radiant heat flux from the burning pallet to the vertical target fuel using

the solid flame radiation model.

Assumptions:

(1) The fire source will be nearly circular.

(2) The correlation for solid flame radiation model is suitable for most fuels.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 05.1_Heat_Flux_Calculations_Wind_Free.xls (click on Solid Flame 2)

FDT Inputs: s

curb -Fuel Spill Area or Curb Area (A ) = 16 ft2

-Distance between Fire Source and Target (L) = 15 ft

1 f1

-Vertical Distance of Target from Ground (H = H ) = 8 ft

-Select Fuel Type: Douglas Fir Plywood

Results*

Radiation Model Radiant Heat Flux

 kW (Btu/ft -sec) 2

Solid Flame 0.30 (0.03)

*see spreadsheet on next page
5-47

Spreadsheet Calculations

FDT : 05.1_Heat_Flux_Calculations_Wind_Free.xls (Solid Flame 2) s

CHAPTER 5. ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET 

FUEL ABO\£ GROUND LEVEL UNDER IMND-FREE CONDITION 

SOLID FLAME RADIATION MODEL 

Va-sion 1805.0 

Th 'bt)WIIg cat:ll.'l0)" tllla' ~ l<t:ll.1tl1~ hat IIU ft"OIII pOOITU b a tllif.tft~ I. 

Th p1 ~ oTUt a• • 1.10H ~ b u 011a' IU l.'ldhOH 1Jaumltt~d 11"0111 a bm • g n t l anar b a tug~t 

IU lpoUOHHI $Ctll~ dl$tUCHIC411 QUIP. :.OtJ~ gDU d l:tJ t> ~'DII IH Hd<IIV .;JUtbU <II? II ~ I{ WU •o Wild . 

Plli'\'IDI~ten In YEllOWCEll S llr~ En~r~d bj' Ul$ UtH . 

Plll'\'lhl$tert ln GREEII CEllS ar$ AubmllUCIIII\' $$ $C~dtr m 1ll$ DROP OOWII f.1EIIU forth$ f\l$1 h i$CUd . 

. .:. 1$ II>6$(IIUtOI1Htlta iH$ <ue ca l h~d ~ $pl$<ld$•Ht<Ud baad o • 1i<IIH$ ' I=*Cift?d "U~ " Pit 

para111 $~"· n t $pi$<Ht •$et t protected <Ud $$CI re to <WJol:l eno" <IH b a WfHge •1tv" ace II($). 

Th c•at)' r• u e tiUREG ' •o •l:l be rea:l be tore <u a~<•l/$ 1$ ~mao; . 

INPUT PARAMETERS 

1.1<16$ 6U 119 Ra' OTFH I {II ) 

E11'ect1Je HMtOTCCtllbU1m Off I$ I !:. ,,..~ f.oi.LSE 

E111 PU tlat;J P) 

~atR~ l:aH Rat~ Q) 

fH l.ol..f~a 01 t;~ AI! a ''-•) 

o tt.'n o: b~tN~u fll~ a ad TaJif.t(l) 

W rttal Dtt.'" O: OTTalif.tTICtll GIOU d (H • H, ) 

OPTIONAL CALCULATION FOR GIVEN HEAT RELEASE RATE 

e,l,ot"ll "r Ci>Uih4 Vllh"" frlllll F"'' Ti'l>' r,t,nlllln4 a.-r vour N RR '"r' t 

THERMAL PROPERTIES DATA 

BURIIIIIG RATE DATA FOR FUELS 

~at III a 

0.01082 1 ;.,~ 'hl ( 

10900t;J· 1;..~ 

100 M 

175.31 •. w 16 .00 11 

15 .00 11 

8 .00 11 

~~•w Calculae 

1.•9',.,, 

+.'S::Zhl 

.·~·~~~ 

fHI l.la" 6 m 119 Ra~ 

..... ;t:gtll ~~c.. .,., g~ 

Bllp lltaiCo utlat I:IS •Ill • • Select Fuel ~ 

-W!~3 ' at ~=-i~ t.1 l 0.0 17 20.000 100 Scroll to d ~ r~ d ru~ 1 t,• p~ 1l~ n 

euaao l 0.0 IS 26.800 100 Click on t $I$C1Ion 

Slt.'IH 0.078 45,700 2.7 

su~ ~ 0.085 40.100 2.7 

na ~ O.OH U ,700 .. ~ptiH 0 .101 u .ooo 1.1 

~!H OD9 40.800 ... :. o: tn~ 0.041 25.800 .. Di ~ 0.018 26.200 S.l 

OI:Q EU ~I 0.085 34.200 0.7 SUZII ~ ODIS U ,700 3.6 

a. ll& ~ 0.055 43,700 2.1 

o, lt ~ OD» 43.200 3.5 

01: ~ I ODIS 4UOO 2.1 ,_, 0.05 1 43.500 3.6 

... 0.054 43.000 .. lr 1a wb Pll ~ 1 0 ll Hvtlroca b o • OD» 46.000 0.7 -6 1 S llbOa TlaU PII~ I flll:l 0.005 28.100 100 

fH lOll, ~<I\IV 0.0~ 39,700 1.7 

::no; 0 11 0.0335 42.600 2.8 

lll=* 0 I OD» 40.000 0.7 

OOI(ji.U fll P\'WOOd 0.01082 10,900 100 

~~ ·s M!d ~ Ea~1 ~t ~ Ea' IV <lit ~ E•' 1t ~ 

- - , 

j 
5-48

E SnMA niiG RADIATIVE HEAT FLUX TO AT ARGET FUEL tr~~: $?1'$~..._ ... \ ('(F:'f:>Pi'< ~«t:M~~~rQ. ) "'&lll:n , .l"~ Zi.), 

SOLID FLAME RADIATION MODEL 

q"= EF· •:t 

\Mere 

Pod Fire Dameter Calculaticn 

AlM = 11rf.il 

D= v(4A to) 

\Mere 

D= 

Emissive Power C<llcUaticn 

E= !e (1041WIIl.l j 

\Mere 

E= 

\4ew Facta C<llcUaticn 

F· •:t .... = 

F· •:tVJ= 

A= 

A,= 

9= 

S= 

h· = 

= 

F· •:t"= 

\Mere 

q"= incident radiali\@ heat tux onthe131'Qet (kW.tn1

) 

E= errissive power of the pool1ire flame (kVllhr{) 

F · -.a= \iew tlctor between target and the flame 

Aw... =surface area of pod ire (m") 

0 =pool ire diamter (m) 

1.38 m 

E= errissive power of the pool1ire flame (kVllhn:t) 

0 =diameter of the pool1ire (m) 

56.51 (k>AOm'i 

lf\!Sjtll t /~ Q ~ t'S)t.'l' \i.,$-1)/,P..I:V "'+.:. •• t'Sf'. ·-1) "tu " '· + 1)~·1)1' · -1 +1)) _, 

lf~Sjtt1 .1@' - I) ~ .. ~S t.'l• (\.$-1)/.pti:V . .., +A.• •• ~Sf-.;'-1) ·~tu '...+I)~ )/, ,..-1) (>+1 ) " 

(h·:t +S:t+1)12S 

(h:/'+S1+1)12S 

(1+S'Y2S 

2RID 

2H·/D 

2HdD 

F· "l.'f' + F -4VJ 

F· o:~v = 10tal wtical \iew tlctor 

R =distance fran center oflhe pool ire to edge of the targ>rt (m) 

H =height oflhe pool ire 1ame (m) 

0 =pool ire diam~r (m) 

Dslancefrom Certer d the Pcd Fire to Ecge of the T..-get C<llculaticn 

R= l+ 00 

\Mere 

R= l+012= 

!-hat Release Rate C<llcUaticn 

Q = m"AH_,.,,(1 • e ~o.~~ 

\Mere 

Q= 

R= dmnce from cer®r oflhe pool h to edge ofthetarga (m) 

l = distance between pool1ire and target (m) 

0 =pool ire diam~r (m) 

5.260 m 

Q = pool1ire heat release r.Jte (k'N,l 

m" = mass burrinQ r.m of fuel per unit surDce area (kQ.tn :.-sec) 

AH = effecti'W heat ofcorrbuslion of fuel (k..Lo1<g) 

A"""= surface area of pool~ (area imolve:l in ~orizalion)(m:.-) 

kP = empirical constant (m ) 

0 = diam~r of pool h (dam~r imoi'Wd in \Gporization, circolarpool is assumed)(m) 

175.31 kW 

Pod Fire Aame Heia-.t Calculation 

H= 0235 0:.-0·1D2 0 

\Mere 

H= 

S= 2RIIl= 

h·= 2H·/D= 

= 2Hw0 = 

A= (h ~ +S:.-+1)12$ = 

H = flane height (m) 

Q =heat release r.Jte of1i"e (kVV) 

0 = 1ire diam~r(m) 

0.453 m 

7.647 

3.545 

2(H-H·)ID= -2.887 

4.710 
5-49

Radiati>R Heel Flux Calculction 

EF 1+Z 

The above calculations are based on principles developed in the SFPE Handbod< of Fire Protection 

EnQineerinQ, 3f4 Edition, 2002. 

Calculations are based on certdin assumptions and have inherent limitations. The results of such 

oollouloltion::; mo7y' or moly not ho1ve re.l::;on.lble prediotive Oolpolbilitie::; for o3 gillen ::;itu.nion, o1nd ::;hould 

only be interpreted by an informed user. 

Anhough each calculation in the spreadsheet has been veri1ied with the results of hand calculation, 

there is no absolute guarantee of the accuracy of these calculations. 

Any questions, comments, concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to rod@nrc.gov or rro<:s3@nrc.gov. 
5-50

Example Problem 5-6: Radiant Heat Flux from a Burning Cable Tray to a Vertical Target Fuel

Example Problem 5.11-6

Problem Statement

A fire scenario may arise from a horizontal cable tray burning in a very large compartment.

The cables in the tray are IEEE-383 unqualified and made of XPE/FRXPE insulation material

(assume that the exposed area of the cable is 20 ft ). A safety-related cable tray is also filled with 2

IEEE-383 qualified made of XLPE insulation material located at a radial distance (L) of 9 ft from the

fire source and 6 ft above the fire source. Calculate the flame radiant heat flux to a target (safety-related

cable tray) using the solid flame radiation model. Is the IEEE-383 qualified cable tray damaged?

Solution

Purpose:

(1) Calculate the radiant heat flux from the burning cable tray to the vertical target cable

tray using the solid flame radiation model.

(2) Determine if the IEEE-383 cable tray (target) is damaged.

Assumptions:

(1) The fire source will be nearly circular.

(2) The correlation for solid flame radiation model is suitable for most fuels.
5-51

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 05.1_Heat_Flux_Calculations_Wind_Free.xls (click on Solid Flame 2)

FDT Inputs: s

-Mass Burning Rate of Fuel = 0.0037 kg/m -sec 2

c,eff -Effective Heat of Combustion of Fuel ( H ) = 28,300 kJ/kg

curb -Fuel Spill Area or Curb Area (A ) = 20 ft2

-Distance between Fire Source and Target (L) = 9 ft

1 f1

-Vertical Distance of Target from Ground (H = H ) = 6 ft

Note: Since the insulation material (XPE/FRXPE) is not available in the thermal

properties data of the spreadsheet, we have to input the mass burning rate and

effective heat of combustion in the spreadsheet. Values of cable materials

properties are available in Table 3-4. Select User-Specified Value, and enter

c,eff the and H values from Table 3-4.

Results*

Radiation Model Radiant Heat Flux

 kW (Btu/ft -sec) 2

Cable Failure

Solid Flame 0.60 (0.05) No,

*see spreadsheet on next page
5-52

Spreadsheet Calculations

FDT : 05.1_Heat_Flux_Calculations_Wind_Free.xls (Solid Flame 2) s

CHAPTER 5. ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET 

FUEL ABO\£ GROUND LEVEL UNDER IMND-FREE CONDITION 

SOLID FLAME RADIATION MODEL 

Va-sion 1805.0 

Th 'bt)WIIg cat:ll.'l0)" tllla' ~ l<t:ll.1tl1~ hat IIU ft"OIII pOOITU b a tllif.tft~ I. 

Th p1 ~ oTUt a• • 1.10H ~ b u 011a' IU l.'ldhOH 1Jaumltt~d 11"0111 a bm • g n t l anar b a tug~t 

IU lpoUOHHI $Ctll~ dl$tUCHIC411 QUIP. :.OtJ~ gDU d l:tJ t> ~'DII IH Hd<IIV .;JUtbU <II? II ~ I{ WU •o Wild . 

Plli'\'IDI~ten In YEllOWCEll S llr~ En~r~d bj' Ul$ UtH . 

Plll'\'lhl$tert ln GREEII CEllS ar$ AubmllUCIIII\' $$ $C~dtr m 1ll$ DROP OOWII f.1EIIU forth$ f\l$1 h i$CUd . 

. .:. 1$ II>6$(IIUtOI1Htlta iH$ <ue ca l h~d ~ $pl$<ld$•Ht<Ud baad o • 1i<IIH$ ' I=*Cift?d "U~ " Pit 

para111 $~"· n t $pi$<Ht •$et t protected <Ud $$CI re to <WJol:l eno" <IH b a WfHge •1tv" ace II($). 

Th c•at)' r• u e tiUREG ' •o •l:l be rea:l be tore <u a~<•l/$ 1$ ~mao; . 

INPUT PARAMETERS 

E11'ect1Je HMtOTCCtllbU1m Off I$ I !:. ,,..~ 

EIII PU tl•t;J P) 

HeatRe l:aH Rat~ Q) 

FH l.ol..f~a 01 t;~ AI! a ''-•) 

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W rttal Ol$t.'l•o: OTTalif.tTICtll GIOU d (H • H, ) 

OPTIONAL CALCULATION FOR GIVEN HEAT RELEASE RATE 

f.oi.LSE 

.. ,

e,r,ot"ll "r el>ulh4 Vllh"" fl'lllll F"'' Ti'l>' 1,1,n1111n4 a.-r vour N RR '"r' t 

~~•w Calculae 

THERMAL PROPERTIES DATA 

BURIIIIIG RATE DATA FOR FUELS 

FHI l.la" 6 m 119 Ra~ 

, .... ;t:glll ~~c.. 

~at III 1 

.,., g~ 

Bllp lrtatc o utl•t I:IS •Ill • • Select Fuel ~ 

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Slt.'IH 0.078 45.700 2.7 

su~ ~ 0.085 40.100 2.7 

na ~ O.OH U .700 .. ~ptiH 0 .101 U .600 1.1 

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a. tl& ~ 0.055 43.700 2.1 

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FH 10 11. ~a\IV 0.0~ 39.700 1.7 

::n o; 0 11 0.0335 42.600 2.8 

lll=* 0 I o•» 40.000 0.7 

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- - , 

j 
5-53

ESTIMATING RADIATIVE HEAT FLU X TO AT ARGET FUEL ~'tt«12 s.-?=H.TdT:o.'\ ('(F:~~«.rbn~ :;: • &Ill en !"~ ): ~ 

SOLID Fl.A ME RADIATION M DDEL 

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5-54

Radiati-.e Heel Flux Calculction 

q"=EF ..,.z 

The above calculations are based on principles developed in the SFPE Handbod< of Fire Protection 

EnQineerinQ, 3f4 Edition, 2002. 

Calculations are based on certdin assumptions and have inherent limitations. The results of such 

calculations may or may not have reasonable predictive capabilities for a given situation, and should 

only be interpreted by an informed user. 

Anhough each calculation in the spreadsheet has been veri1ied with the results of hand calculation, 

there is no absolute guarantee of the accuracy of these calculations. 

Any questions, comments, concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to rod@nrc.gov or rro<:s3@nrc.gov. 
6-1

CHAPTER 6. ESTIMATING THE IGNITION TIME OF A TARGET FUEL 

EXPOSED TO A CONSTANT RADIATIVE HEAT FLUX

6.1 Objectives

This chapter has the following objectives:

• Explain the importance of the location of the ignition source.

• Explain the importance of the position, spacing, and orientation of the fuel(s).

• Describe ignition parameters.

• Discuss how to calculate ignition time.

• Define relevant terms, including ignition temperature, flash point, piloted ignition,

and non-piloted ignition.

6.2 Introduction

When performing a fire hazard analysis (FHA), it is essential to understand ignition of materials

since the ignition of a combustible material is typically the first step in any fire scenario. Moreover,

once a fire starts, the ignition delay times of other materials, coupled with flame spread, will affect

the rate at which the fire spreads and develops. Thus, secondary ignition of other materials is

another important step in fire development.

Theories regarding ignition and flame spread on solids are based on the concept of a critical

ig surface temperature called the ignition temperature, T . This critical surface temperature is related

to the flash point (the lowest temperature at which a flammable vapor/air mixture exists at the

surface) in the ignition of liquids for the case of piloted ignition, or the auto-ignition temperature if

no pilot is present. The flash point phenomenon can be observed with solids under conditions of

surface heating, but cannot be defined in terms of a bulk temperature. Because solid fuel must

decompose to create fuel vapors (rather than simply evaporating), there is not a unique flash point

temperature for a solid fuel. Both piloted and automatic ignition occur in an identical fashion for the

evaporated or decomposed fuel gases of liquid and solid fuels, respectively, as illustrated in Figure 6-1.

Figure 6-1 Ignition Processes for Liquid and Solid Fuels
6-2

For ignition to occur, the solid fuel must be heated sufficiently to vaporize and form a flammable

pre-mixed system (see Figure 6-2). An ignition source, such as a spark or small flame must also

be present, for piloted ignition or the gas mixture must be heated sufficiently to cause auto-ignition.

The critical surface temperature at which these ignitions occur is called the ignition temperature,

Tig. Piloted ignition requires a much lower temperature than automatic (or spontaneous) ignition.

For example, wood has a typical piloted ignition temperature of 350 °C (662 °F) and 600 °C

(1,112 °F) for auto-ignition. Ignition temperature can be considered to be a property of the solid,

but it is not truly constant and can vary with the rate of heating.

Figure 6-2 External Radiation to a Solid Target Object

from a Flame or Hot Surface at Elevated Temperature

Heating of solids to ignition can be accomplished by radiation from flames or hot gases, by flame

contact, or by contact with hot gases. In any of these cases, the measure of the severity of the

heating sources is the heat flux, usually measured in kW/m (Btu/ft -sec). Table 6-1 lists typical 2 2

heat fluxes from various sources, which clearly show the significance of radiation in fires.

Table 6-1. Typical Heat Fluxes from Various Sources

Source Heat Flux

(kW/m )

2

Comment

Flame radiation 0–200 Depends on size of flame and distance from the flame

Flame convection 10–20 Direct flame contact

Hot gas convection 0–10 Direct gas contact

Hot gas radiation 1–150 Depends on gas temperature, soot concentration, and

distance from hot gases
6-3

6.3 Ignition Sources and Fire Development

An ignition source can consist of a spark with a low energy content, a heated surface, or a large

pilot flame. The source of energy can be chemical, electrical, or mechanical. The greater the

energy of the ignition source, the faster the fire will subsequently grow on the fuel source surface.

A spark or a glowing cigarette may initiate smoldering combustion, which may continue to smolder

for a long time before flaming combustion begins. The smoldering often producing low heat but

considerable amounts of toxic gases. A pilot flame usually produces flaming combustion and

results in quicker flame spread and fire growth.

The location of the ignition source is also very important. For example, a pilot flame positioned at

the lower end of a window curtain may cause rapid upward flame spread and fire growth.

By contrast, the same pilot flame placed at the top of the curtain would cause much slower fire

growth with a slow, downward flame spread. 

The position of the fuel can also have a marked effect on fire development. If the fuel is burning

away from walls, the cool air is entrained into the plume from all directions. When the fuel is close

to a wall, however, the entrainment of cold air is limited; this causes higher temperatures and

higher flames since combustion must take place over a greater distance.

The spacing and orientation of the fuels are also important. The spacing in the compartment

determines, to a considerable extent, how quickly the fire spreads between the fuel packages.

Upward flame spread on a vertically oriented fuel surface will occur more rapidly than lateral spread

along a horizontally oriented fuel surface. Similarly, a fuel package with a large surface area will

burn more rapidly than an otherwise equivalent fuel package with a small surface area. A pile of

wooden sticks, for example, will burn more rapidly than a single log of wood of the same mass.

6.4 Ignition Time for Thermally Thick Materials

Ignition time can be computed by calculating the time to achieve sufficient vaporization to result in

a flammable mixture plus the time for the mixture to ignite. Except for cases of low ambient oxygen,

the gas phase process is much faster than the heating time of a solid. Typical values of sufficient

mass loss rates (burning rates) to enable ignition are on the order of 2 to 6 g/m . These values are 2

associated with the initiation of pyrolysis (combustion). Hence, ignition time for a solid can be

effectively computed by simple heat conduction theory. The surface of the solid must be heated

ig to its ignition temperature, T . Table 6-2 lists measured ignition times for typical thick solid fuels.
6-4

Table 6-2. Typical Ignition Times of Thick Solid Fuels (Quintiere, 1997)

Materials Heat Flux

(kW/m )

2

Time to Ignition 

ig t 

(sec)

Plexiglas, Polyurethane foam, Acrylate carpet 10 300

Wool carpet 20 70

Paper of gypsum board 20 150

Wood particle board 20 250

Polyisocyanurate foam 30 5

Wool/nylon carpet 30 70

Hardboard 30 150

The steady-state surface temperature of a thermally thick fuel is independent of the material’s

physical properties. The rate of heating and the time required to reach steady-state are material

dependent. At steady-state, the incident heat is entirely lost to the surrounding surface by

convection and re-radiation, but the temperature of the fuel remains constant. The heat flux

ig required to adjust the surface temperature to the ignition temperature, T , is known as the critical

heat flux (CHF). Ignition or flame spread is not possible below the threshold level of heating

represented by the CHF. 

6.4.1 Method of Tewarson

As a fuel surface is exposed to heat flux, most of the heat is transferred to the interior of the

material. The ignition principle suggests that the rate with which heat is transferred depends on the

ig a

ignition temperature (T ), ambient temperature, (T ), material thermal conductivity (k), material

specific heat (c), and the material density ( ). The combined effects are expressed by a parameter

defined as the thermal response parameter (TRP), of the material as follows (Tewarson, 1995):

 (6-1)

Where:

TRP = thermal response parameter (kW-sec /m )

1/2 2

Tig ig a = (T - T ) = ignition temperature above ambient (K)

k = material thermal conductivity (kW/m-K)

c = material specific heat (kJ/kg-K)

ρ = material density (kg/m )

3
6-5

TRP is a useful parameter for engineering calculations to assess resistance to ignition and flame

spread. The important material variables in the above equation are k c. These variables combine

to form a material’s thermal inertia. (See Chapter 2, Section 2.6.1 for a more detailed discussion

of thermal inertia.) For most materials, c does not vary significantly, and the thermal conductivity

is largely a function of the material density. This means that density is the most important material

property. Low-density materials are excellent thermal insulators because heat does not readily

pass the material, the surface of the material actually heats more rapidly and, as a result, can be

ignited more quickly. For thin materials, the weight or thickness plays an important role.

The ignition principle suggests that, for thermally thick materials, the inverse of the square root of

ignition time is expected to be a linear function of the external heat flux away from the CHF value

(Tewarson, 1995):

 (6-2)

 (6-3)

Where:

ig t = ignition time (sec)

= external heat flux (kW/m )

2

CHF = critical heat flux for ignition (kW/m )

2

TRP = thermal response parameter (kW-sec /m )

1/2 2

The above equation applies to the transient period (before steady-state). Most common materials

behave as thermally thick materials and satisfy Equation 6-3. The CHF and TRP values for

materials are derived from the ignition data measured in the Flammability Apparatus, a commercial

instrument designed by the Factory Mutual Research Corporation (FMRC) for measuring benchscale HRR based on the oxygen consumption calorimetry. The CHF and TRP values for various

materials are listed in Table 6-3. The CHF are extrapolated from the experimental correlation when

the time to ignition goes to infinity, thus making CHF dependent on the model used for correlating

the data. The minimum heat flux for ignition should not be confused with the CHF for ignition.

Jenssens (1991) defined minimum heat flux for ignition and CHF for ignition as follows:

• Minimum heat flux for ignition is the heat flux below which ignition under practical condition

(in bench-scale test or real-scale test cannot occur).

• CHF for ignition is an estimate of minimum heat flux derived from a correlation of

experimental data.
6-6

Table 6-3. Critical Heat Flux and Thermal Response Parameters of Selected Materials

(Tewarson, 1995, © SFPE. With permission.)

Material Critical Heat

Flux (CHF) 

 (kW/m )

2

Thermal Response

Parameter (TRP)

(kW-sec /m )

1/2 2

Electrical Cables: Power

PVC/PVC

PE/PVC

PVC/PE

Silicone/PVC

Silicone/crosslinked polyolefine

EPR (ethylene-propylene rubber/EPR)

XLPE/XLPE

XLPE/EVA (ethyl-vinyl acetate)

XLPE/Neoprene

XLPO/XLPO

XLPO, PVF, (polyvinylidine fluoride)/XLPO

EPR/Chlorosulfonated PE

EPR, FR

13–25

15

15

19

25–30

20–23

20–25

12–22

15

16–25

14–17

14–19

14–28

156–341

221–244

263

212

435–457

467–567

273–386

442–503

291

461–535

413–639

283–416

289–448

Electrical Cables: Communications

PVC/PVC

PE/PVC

XLPE/XLOP

Si/XLOP

EPR-FR

Chlorinated PE

ETFE/EVA

PVC/PVF

FEP/FEP

15

20

20

20

19

12

22

30

36

131

183

461–535

457

295

217

454

264

638–652

Synthetic Materials

Polypropylene

Nylon

Polymethylmethacrylate (PMMA)

Polycarbonate

Polycarbonate panel

15

15

11

15

16

193

270

274

331

420

Natural Materials

Wood (red oak)

Wood (Douglas fir)

Wood (Douglas fir/fire retardant, FR)

Corrugated paper (light)

10

10

10

10

134

138

251

152
6-7

For first order approximation of ignition of solids, this discussion is highly simplified and ignores

several secondary aspects of the process. Nonetheless, the discussion shows that two properties

of a thick solid fuel significantly affect its ignition behavior. The ignition temperature of the solid is

clearly important and reflects the thermal stability of the material. Ignition temperature can be

thought of as a chemical property. Materials that are thermally stable are difficult to ignite and

exhibit higher ignition temperatures. The primary physical property of the material is its density.

The surface of low density material heats more rapidly, causing more rapid ignition of the material.

Table 6-4 summarizes typical ignition data for various materials.

Table 6-4. Ignition Temperature and Thermal Properties of Materials

(Quintiere, 1997)

Materials Ignition

Temperature

T ig

(°C)

Density

(kg/m )

3

Thermal

Conductivity

k 

(kW/m-K)

Specific

Heat

c 

(kJ/kg-K)

Thermal

Inertia

k c

(kW/m -K) -sec 2 2

Polymethylmethacrylate

(PMMA)

278 1200 0.00026 2.1 0.66

Polyurethane foam 280 20 0.000034 1.4 0.00095

Douglas fir particle board

(1.23 cm)

382 650 0.00011 2.0 0.14

Plywood plain 

(1.23 cm)

390 540 0.00012 2.5 0.16

Polystyrene foam

(5.08 cm)

630 20 0.000034 1.5 0.0010

To obtain ignition time, several correlations are available in the literature. Although each correlation

uses the CHF and critical surface temperature criterion, each technique correlates the data

differently resulting in method-specific values for pseudo material properties required in the

analysis. Four more techniques are presented for calculating the time to ignition for thermally thick

materials under constant radiative heat flux. These methods are based on the principles from

SFPE Engineering Guide, “Piloted Ignition of Solid Materials Under Radiant Exposure.”
6-8

6.4.2 Method of Mikkola and Wichman (SFPE Engineering Guide, 2002)

The time to ignition can be calculated using following correlation:

 (6-4)

Where:

ig t = ignition time (sec)

k c = material thermal inertia (kW/m K) -sec 2 2

Tig = ignition temperature (°C)

Ta = ambient air temperature (°C)

= external heat flux (kW/m )

2

= critical heat flux for ignition (kW/m )

2

6.4.3 Method of Quintiere and Harkleroad (SFPE Engineering Guide, 2002)

The time to ignition can be calculated using following correlation:

 (6-5)

Where:

ig t = ignition time (sec)

= minimum heat flux (kW/m )

2

= critical heat flux for ignition (kW/m )

2

 b = flame spread parameter (1/ psec)
6-9

6.4.4 Method of Janssens (SFPE Engineering Guide, 2002)

The time to ignition can be calculated using following correlation:

 (6-6)

Where:

ig t = ignition time (sec)

k c = material thermal inertia (kW/m K) -sec 2 2

hig = heat transfer coefficient at ignition (kW/m -K) 2

= external heat flux (kW/m )

2

= critical heat flux for ignition (kW/m )

2

The above three correlations used the material properties listed in Table 6-5.
6-10

Table 6-5. Ignition and Flame Spread Properties of Materials

(SFPE Engineering Guide, 2002. With permission.)

Materials Ignition

Temperature

T ig

(°C)

Thermal Inertia

k c 

(kW/m K) -sec 2 2

Minimum Heat

Flux for Ignition

(kW/m )

2

Flame Spread

Parameter

b

(1/ psec)

PMMA Polycast (1.59mm) 278 0.73 9 0.04

Hardboard (6.35 mm) 298 1.87 10 0.03

Carpet (Arcylic) 300 0.42 10 0.06

Fiber Insulation Board 355 0.46 14 0.07

Hardboard (3.175mm) 365 0.88 14 0.05

PMMA Type G 

(1.27 cm)

378 1.02 15 0.05

Asphalt Shingle 378 0.7 15 0.06

Douglas Fir Particle Board

(1.27 cm)

382 0.94 16 0.05

Plywood Plain 

(1.27 cm)

390 0.54 16 0.07

Plywood Plain 

(0.635 cm)

390 0.46 16 0.07

Foam Flexible 

(2.54 cm)

390 0.32 16 0.09

GRP (2.24 mm) 390 0.32 16 0.09

Hardboard 

(Gloss Paint) (3.4 mm)

400 1.22 17 0.05

Hardboard 

(Nitrocellulose Paint)

400 0.79 17 0.06

GRP (1.14 mm) 400 0.72 17 0.06

Particle Board 

(1.27 cm Stock)

412 0.93 18 0.05

Carpet 

(Nylon/Wool Blend)

412 0.68 18 0.06
6-11

Table 6-5. Ignition and Flame Spread Properties of Materials (continued)

(SFPE Engineering Guide, 2002. With permission.)

Materials Ignition

Temperature

T ig

(°C)

Thermal Inertia

k c 

(kW/m K) -sec 2 2

Minimum Heat

Flux for Ignition

(kW/m )

2

Flame Spread

Parameter

b

(1/ psec)

Gypsum Board, Wallboard

(S142M)

412 0.57 18 0.07

Carpet # 2 

(Wool Untreated)

435 0.25 20 0.11

Foam, Rigid (2.54 cm) 435 0.03 20 0.32

Fiberglass Shingle 445 0.5 21 0.08

Polyisocyanurate 

(5.08 cm)

445 0.02 21 0.36

Carpet # 2

(Wool Treated)

455 0.24 22 0.12

Carpet # 1 

(Wool, Stock)

465 0.11 23 0.18

Aircraft Panel Epoxy

Fiberite 

505 0.24 28 0.13

Gypsum Board FR 

(1.27 cm)

510 0.4 28 0.1

Polycarbonate 

(1.52 mm)

528 1.16 30 0.06

Gypsum Board (Common)

(1.52 mm)

565 0.45 35 0.11

Plywood FR (1.27 cm) 620 0.76 44 0.1

Polystyrene (5.08 cm) 630 0.38 46 0.14
6-12

6.4.5 Method of Toal, Silcock, and Shields (SFPE Engineering Guide, 2002)

The time to ignition can be calculated using following correlation:

 (6-7)

Where:

ig t = ignition time (sec)

FTP = flux time product (kW-sec/m )

2 n

= exposure or external heat flux (kW/m )

2

= critical heat flux for ignition (kW/m )

2

n = flux time product index (n $1)

Equation 6-7 uses the material properties listed in Table 6-6.

Table 6-6. Ignition and Flame Spread Properties of Materials

(SFPE Engineering Guide, 2002. With permission.)

Materials Flux Time Product

FTP 

(kW-sec/m )

2 n

Critical Heat Flux 

(kW/m )

2

Flux Time Product

Index 

n

Chipboard 5,370 6.4 1.49

Chipboard 

(Horizontal) (15 mm)

9,921 9 1.7

Chipboard 

(Vertical) (15 mm)

11,071 10 1.7

Fiberboard 3,981 8.3 1.66

Hardboard 8,127 8.1 1.49

Hardboard 

(Painted Gloss)

9,332 8.1 1.51

Hardwood 2,818 8.1 1.5

Plywood 6,164 10.6 1.51

Plywood 

(Horizontal) (12 mm)

5,409 8.5 1.5

Plywood 

(Vertical) (12 mm)

42,025 10 2
6-13

Table 6-6. Ignition and Flame Spread Properties of Materials (continued)

(SFPE Engineering Guide, 2002. With permission.)

Materials Flux Time Product

FTP 

(kW-sec/m )

2 n

Critical Heat Flux 

(kW/m )

2

Flux Time Product

Index 

n

Plywood 

(Painted Gloss)

6,761 11.4 1.5

PMMA (Cast) (3mm) 3,100 5 1.25

PMMA 

(Extruded) (2 mm)

1,290 9 1

Polyethylene (2mm) 2,220 12.5 1

Polypropylene 

(3.3 mm)

8,110 6.5 1.5

PVC 

(Extruded Gray) (3 mm)

5,130 15 1.5

PVC 

(Pressed White) (3 mm)

95,000 8 2

Softwood 5,130 13.7 1.53

Softwood 

(Horizontal) (20 mm)

44,079 10 2.2

Softwood 

(Vertical) (20 mm)

16,502 12 1.9

Softwood Intumescent

Paint

4,569 13 1.5
6-14

6.5 Assumptions and Limitations

The methods discussed in this chapter are subject to several assumptions and limitations.

(1) For ignition to occur, a solid material must be heated sufficiently to vaporize and form a

flammable mixture.

(2) Ignition occurs when the surface reaches a critical temperature defined as the ignition

temperature. 

(3) A heat source must be present to ignite the solid.

(4) The solid is assumed to be infinitely thick.

(5) The methods are all derived through the solid with radiant heating on the surface.

6.6 Required Input for Spreadsheet Calculations

(1) Target fuel type (material)

(2) Exposed radiative heat flux to target (kW/m )

2

6.7 Cautions

(1) Use (06_Ignition_Time_Calculations.xls) spreadsheet on the CD-ROM for calculations.

(2) Make sure to enter to use correct parameters in the correct units.

6.8 Summary

This chapter discusses ignition phenomena associated with thermally thick materials, as well as

material properties that have major effects on ignition and flame spread. For thin materials, the

weight or thickness of the material plays a very important role. For thick materials, the density of

the material has a major impact on ignition and flame spread rates.
6-15

6.9 References

Quintiere, J.G., Principles of Fire Behavior, Delmar Publishers, Albany, New York, 1997.

SFPE Engineering Guide, “Piloted Ignition of Solid Materials Under Radiant Exposure,” Society of

Fire Protection Engineers, Bethesda, Maryland, January 2002.

Tewarson, A., “Generation of Heat and Chemical Compounds in Fires,” Section 3, Chapter 4, SFPE

Handbook of Fire Protection Engineering, 2 Edition, P.J. DiNenno, Editor-in-Chief, National Fire nd

Protection Association, Quincy, Massachusetts, 1995.

6.10 Additional Readings

Fire Dynamics, Course Guide, Federal Emergency Management Agency (FEMA), United States

Fire Administration (USFA), National Emergency Training Center, Emmitsburg, Maryland, 1995.

Janssens, M.L., “Fundamental Thermophysical Characteristics of Wood and their Role in Enclosure

Fire Growth,” Doctor of Philosophy Dissertation, University of Gent, Belgium, September 1991.

Karlsson, B., and J.G. Quintiere, Enclosure Fire Dynamics, Chapter 2, “A Qualitative Description

of Enclosure Fires,” CRC Press LLC, New York, pp. 11–24, 1999.
6-16

6.11 Problems

Example Problem 6.11-1

Problem Statement

Calculate the ignition time for a PVC/PE power cable, assuming that a 6.5-ft (2-m) diameter pool

fire produces a 25-kW/m heat flux. 2

Solution

Purpose:

(1) Calculate the ignition time for a PVC/PE power cable.

Assumptions:

(1) The material is infinitely thick.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 06_Ignition_Time_Calculations.xls (click on Ignition_Time _Calculations3)

FDT Input Parameters: s

-Exposure or External Radiative Heat Flux to Target Fuel = 25 kW/m2

-Click on the option button (¬) for Electrical Cables - Power

-Select Material: PVC/PE

Results*

Material ig Ignition Time (t )

(min.)

Method of Tewarson

PVC/PE 9.0

 *see spreadsheet on next page
6-17

Spreadsheet Calculations

FDT : 06_Ignition_Time_Calculations.xls (Ignition_Time _Calculations3) s

CHAPTER 6. E SDMATIIIG THE IGIIITIOII Tllvl: OF A TARGET FUEL EXPOSED TO A 

CO liST AliT RADIA DVE HEAT FLUX 

Version 1805.0 

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6-18

ESTIMATING IGNrTIONTII.IE FOR COMBUSTIBLES 

METHOD OFTEWARSON 

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6-19

Example Problem 6.11-2

Problem Statement

Determine the time for 2-inch-thick Douglas fir plywood to ignite when it is subjected to a flame heat

flux of 25 kW/m , assuming the surface of the plywood is initially at 68 °F (20 °C). 2

Solution

Purpose:

(1) Calculate the ignition time of Douglas fir plywood.

Assumptions:

(1) The material is infinitely thick.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 06_Ignition_Time_Calculations.xls (click on Ignition_Time _Calculations3)

FDT Input Parameters: s

-Exposure or External Radiative Heat Flux to Target Fuel = 25 kW/m2

-Click on the option button (¬) for Natural Materials 

-Select Material: Wood (Douglas fir)

Note: The ignition time calculation method (Tewarson) provided in the spreadsheet

Ignition_Time _Calculations3 does not require the material thickness or initial

surface temperature; therefore, material thickness and temperature are additional

information only. However, if the initial temperature of the material is relatively high

(compare with ambient temperature range), the ignition time value definitely will not

be realistic based on this method. Also, we are assuming the material as infinitely

thick to use the method; thus, we do not have to consider the thickness for this

problem.

Results*

Ma ig terial Ignition Time (t )

(min.)

Method of Tewarson

Wood

(Douglas fir)

1.11

*see spreadsheet on next page
6-20

Spreadsheet Calculations

FDT : 06_Ignition_Time_Calculations.xls (Ignition_Time _Calculations3) s

CHAPTER 6. E SDMATIIIG THE IGIIITIOII Tllvl: OF A TARGET FUEL EXPOSED TO A 

CO liST AliT RADIA DVE HEAT FLUX 

Version 1805.0 

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6-21

ESTIMATING IGNrTIONTII.IE FOR COMBUSTIBLES 

METHOD OFTEWARSON 

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7-1

CHAPTER 7. ESTIMATING THE FULL-SCALE HEAT RELEASE RATE

OF A CABLE TRAY FIRE

7.1 Objectives

This chapter has the following objectives:

• Describe the numerous functions that electrical cables perform in a nuclear power plant (NPP).

• Explain the factors that determine how a cable will behave in a fire.

• Describe the ways that fires can occur in cable tray installations.

• Discuss the various types of combustion reactions.

• Explain the processes that electrical failures can initiate in a cable tray.

7.2 Introduction

Fires in grouped electrical cable trays pose distinct fire hazards in power generating facilities.

In the past, cable tray installations have caused fires that resulted in serious damage to NPPs.

In fact, during the 1950s and early 1960s, NPPs in the United States experienced several fires

with serious losses propagated by electrical cables. A 1966 NFPA fire hazard study (Hedland, 1966)

described 24 such fires, the most serious of which occurred at the Peach Bottom Atomic Power

Station operated by Philadelphia Electric Company. The most important aspect of the NAPA study,

however, is that it pointed out (probably for the first time) that grouped cables can spread flame

much faster than individual cables.

The 1975 fire at the Browns Ferry Nuclear Power Plant (BFNP) operated by the Tennessee Valley

Authority (TVA) demonstrated the vulnerability of electric cables installed in an NPP when exposed

to elevated temperatures as a result of a fire. In response to the Browns Ferry incident, the NRC’s

Executive Director for Operations (EDO) established a special review group to identify lessons that

can be learned from the event and to make recommendations for the future treatment of cable trays

and cable fires (NUREG-0050). After the BFNP fire, the NRC conducted a series of operating plant

inspections and thorough reviews of NPP fire protection programs. On the basis of this information,

the NRC issued new fire protection requirements in 10 CFR 50.48 and Appendix R to 10 CFR Part 50.

The new regulations imposed a minimum set of fire protection program and post-fire safe-shutdown

(FSSD) requirements. (See Appendix A for more on electrical cables.)

Electrical cables perform numerous functions in an NPP:

• power cables that supply electricity to motors, transformers, and heaters

• lighting cables that supply electricity to normal lighting fixtures and fluorescent lighting ballasts

• control cables that connect plant equipment such as motor-operated valves (MOVs)

and motor starters to remote initiating devices (e.g., switches, relays, and contacts)

• instrumentation cables that transmit low-voltage signals between input devices

(e.g., readout panels)

• communication cables (telephone lines)

• heat tracing cables.
7-2

The primary cables of concern for FSSD of the reactor are typically power, control, and

instrumentation cables. The function of a given cable dictates its acceptable operating parameters.

These parameters are important because what constitutes acceptable performance of one type of

cable at elevated fire temperatures may not be acceptable performance for another (e.g., a cable

that demonstrates acceptable performance for power applications at a certain elevated fire

temperature may not be acceptable for instrumentation applications at the same temperature).

Power cables are the least susceptible to fire-induced failure. Control cables are more susceptible

to such failure than power cables but typically less susceptible than instrument cables, which are

often the most easily affected by elevated temperatures and the first to suffer fire-induced failures.

7.3 Cable Tray Fire Burning Mode Classification

Electrical cables constitute a serious fire hazard for NPPs because the combustible polymeric

insulation and jacket material are present in large quantities. This large fuel load can cause NPP

fires to burn for extended periods. To compound the problem, the combustion of a fully developed

cable fire may be incomplete because of the presence of smoke; whereas general building fires on

ground level usually burn in the presence of clear air, because smoke escapes through windows

and doors before descending to the fuel.

The behavior of cables in a fire depends on a number of factors, including their constituent

materials and construction, as well as their location and installation geometry. The component

material and the construction of the cable are very important, as is the nature of the given fire.

For example, polymer-insulated cables are regarded as fire hazards because all organic materials

will burn under most fire conditions and will liberate heat and toxic gases (such as carbon

monoxide.) Depending on their location and means of installation, cables can contribute to a fire

in a number of ways. For example, burning cables can propagate flames from one area to another

or they can add to the amount of fuel available for combustion and can liberate smoke containing

toxic and corrosive gases. Similarly, the grouped cables could pose a more serious threat in

situations where they run through open spaces connecting different parts of an NPP. In these

situations, the cables could propagate and spread the fire between compartments. Thus,

the hazards associated with burning cables must be considered in the context of the surroundings.

Sometimes, cables comprise a very small proportion of the combustible material; in other situations,

they can be the major contribution.

Cable tray fires can occur from various sources. The scenarios of concern include (1) a fire within

a cable tray (regardless of how it is initiated) and (2) as exposure fire (i.e., a fire that originates

outside of the cable tray and subsequently ignites the cable tray). It is common practice to consider

only self-ignited cable fires to occur in power cable trays since they carry enough electrical energy

for ignition. Control and instrumentation cables typically do not carry enough electrical energy for

self ignition.
7-3

To determine the behavior of a given type of cable, they are subject to a variety of standard smalland large scale tests. As stated in NUREG/CR-2431, “Burn Mode Analysis of Horizontal Cable

Tray Fires,” February 1982, the cable fire growth tests performed to date have demonstrated

different burn modes in horizontal and vertical configurations. The results of horizontal and vertical

cable tray tests showed that jacket or insulation material may melt (thermoplastic) or form a

considerable char (thermoset). The insight gained from the various cable tray fire tests indicate

different types of combustion reactions.

• In pyrolysis, flaming was uniform over the outer surface of the cable bundle and throughout

the cable bundle. The cable region involved in the fire grew steadily for the duration of the test.

• With smoldering and/or melting, the jacket and/or insulation material melted and coalesced

into a large mass, and flaming occurred principally on the outer surface of the fused mass.

Fire involvement depended upon the shape and position of the fused mass within the cable tray.

• With deep-seated combustion, the jacket and/or insulation material formed considerable

char, and flaming occurred principally on the outer surface of the cable bundle. Flaming

was neither continuous nor uniform, but rather occurred as sporadic bursts of fire. After the

surface flaming subsided, a glowing cable region slowly progressed along the cables with

sporadic flaming issuing from the region. The deep-seated fire, as a subclass of smoldering

combustion, is defined as having a fuel interior temperature between the fuel vapor and

surface auto-ignition temperatures of the fuel and a fuel surface temperature below the

upper or surface auto-ignition temperature.

• Interior combustion resulted in uniform flaming over the outer surface and throughout the

cable bundle. The cable region involved in the fire grew steadily and continuously, and the

surface fire slowly progressed along the cable with sporadic flaming.

7.4 Cable Tray Heat Release Rate

As stated above, cable insulation and jacket material dominates the combustible fuel loading in

most NPP areas. Most of this material is found on cables that are routed in extensive cable tray

arrays. Review of the literature on cable tray fires indicates that there are no reliable correlations

for the rate of heat release from a full-scale fire. The most systematic studies available are those

from Tewarson, et al. (1979), and Sumitra (1982). A useful engineering analysis and basic

correlation of their data has been prepared by Lee, 1985, who showed that the peak full-scale HRR

can be predicted according to the bench-scale HRR measurements. Lee’s correlation for the HRR

from measured data is based on the following equation:

 (7-1)

Where:

= full-scale HRR (kW)

= bench-scale HRR (kW/m )

2

Af = exposed cable tray area actively pyrolyzing (m )

2
7-4

The bench-scale HRR , is the peak value measured under the heat flux condition of 60 kW/m .

2

The py frolysis or burning area, A , can vary with time as a cable fire spreads. For screening

purposes, this area can be estimated assuming area of the fuel involved in fire.

The bench-scale HRR data for a number of cable types measured by Tewarson, et al., and Sumitra,

are tabulated in Table 7-1. Note that polyethylene/polyvinylchloride (PE/PVC) cables were the most

flammable of all cables tested.

Table 7-1. Bench-Scale HRR of a Cable Tray Fire

Cable Sample Bench-Scale HRR per Unit Area

(kW/m )

2

ld PE 1,071

PE/PVC 589

XPE/FRXPE 475

XPE/Neoprene 354

PE, PP/Cl.S.PE 345

XPE/Neoprene 302

FRXPE/Cl.S.PE 258

PE, Nylon/PVC, Nylon 231

XPE/Cl.S.PE 204

Silicone, glass braid, asbestos 182

XPE/XPE 178

PE, PP/Cl.S.PE 177

Silicone, glass braid 128

Teflon 98

Cl.S. - Chlorosulfonated; FRXPE - Fire Retardant Crosslinked Polyethylene; 

PE - Polyethylene; PP - Polypropylene; PVC - Polyvinylchloride;

XPE - Crosslinked Polyethylene
7-5

Typically, the IEEE-383-qualified cables are thermoset material, while the unqualified cables

are constructed of thermoplastic material. Table 7-2 lists commonly found cables.

Table 7-2. Thermoplastic vs. Thermoset Cables

Thermoplastic Cable Construction

Allied Chemical’s Halar (ethylene copolymer with chlorotrifluoroethylene)

DuPont’s PFA (perflouroalkoxy branched polymers)

Dynamit Nobel’s Dyflor (polyvinylidene fluoride)

Ethylenetetrafluoroethylene (ETFE) (known as Tefzel )

®

Fluorinated polyethylene-polypropylene (FEP) (known as Teflon )

®

Low and high polyethylene (PE)

Nylon, chlorinated polyethylene (CPE)

Polyvinyl chloride (PVC)

Polyvinyl fluoride (PVF) (known as Tedlar )

®

Polyurethane, polypropylene (PPE)

Polytetrafluoroethylene (PTFE) (known as Teflon )

®

Teflon, and fluorinated polymers such as DuPont’s TFE copolymers with ethylene

(known as Tefzel )

®

Thermoset Cable Construction

Crosslinked polyethylene (XLPE)

Crosslinked polyolefin (XLPO)

Chloroprene rubber (CR)

DuPont’s Hypalon (Chlorosulphonated polyethylene)

Ethylvinyl acetate (EVA)

Ethylene propylene rubber (EPR)

Nitrile or rubber butadiene nitrite (NBR)

Styrene butadiene rubber (SBR)

Polybutadiene, neoprene, and silicone rubber

7.5 Cable Failure Criteria (Critical Temperature and Critical Heat Flux)

Electrical failure can initiate several fire-related processes, such as melting, pyrolysis, gasification,

ignition, and combustion of cable. The lower the heat flux requirement to ignite the electrical

cables, the greater the fire hazard is in terms of ignition and flame spread.

A quantitative FHA requires a damage threshold for cables exposed to fires. Electrical cables

are typically the primary target for most analyses. The two general types of electrical cables

that are anticipated in an NPP are qualified and unqualified. These terms respectively refer to

cables that pass or fail the fire test defined in the IEEE-383 standard promulgated by the Institute

of Electrical and Electronic Engineers (IEEE). See Appendix A, Section A.5.8, for a discussion of

cable damage threshold exposure heat-flux.
7-6

7.6 Assumptions and Limitations

The method discussed in this chapter is subject to several assumptions and limitations:

(1) This correlation is based on the data obtained from flaming fire of cable samples.

(2) A complex cable tray configuration may be present in many NPPs. For very complex cable

tray arrays, the above correlation would give a less accurate approximation for the HRR.

(3) The equation should be used to calculate the HRR for any type of cable.

7.7 Required Input for Spreadsheet Calculations

The user must obtain the following information before using the spreadsheet:

(1) cable type (material)

(2) exposed cable tray burning area (ft )

2

7.8 Cautions

(1) Use (07_Cable_HRR_Calculations.xls) spreadsheet on the CD-ROM for calculation.

(2) Make sure to enter the input parameters in the correct units.

7.9 Summary

There is currently no direct HRR data available on the burning of full-scale or intermediate-scale

cable tray arrays. Available mass loss data, measured in a series of intermediate-scale fires, was

used to estimate HRR. The resulting HRR, in turn, was used to develop a predicted method for fullscale fire behavior based on the bench-scale HRR data for cables.

Estimating the HRR, , of cables involves the following steps:

(1) Determine the bench-scale HRR, .

f

(2) Calculate the exposed cable tray area, A .
7-7

7.10 References

“Fire-Induced Vulnerability Evaluation (FIVE) Methodology,” EPRI TR-100370, Electric Power

Research Institute, Palo Alto, California, 1992.

Hedlund, C.F., “Grouped Combustible Wire and Cables,” Fire Journal, Volume 60, pp. 5–8,

March 1966.

Lee, B.T., “Heat Release Rate Characteristics of Some Combustibles Fuel Sources in Nuclear

Power Plants,” NBSIR 85-3195, U.S. Department of Commerce, National Bureau of Standards

(NBS), Washington, DC, July 1985.

NUREG-0050, “Recommendations Related to Browns Ferry Fire,” Report by Special Review Group,

U.S. Nuclear Regulatory Commission, Washington, DC, February 1976.

NUREG/CR-2431, “Burn Mode Analysis of Horizontal Cable Tray Fires,” U.S. Nuclear Regulatory

Commission, Washington, DC, February 1982.

Sumitra, P.S., “Categorization of Cable Flammability. Part I, Intermediate-Scale Fire Tests of Cable

Tray Installations,” Interim Report NP-1881, EPRI Research Project 1165-1, Factory Mutual

Research Corporation, Norwood Massachusetts, 1982.

Tewarson, A., J.L. Lee, and R.F. Pion, “Categorization of Cable Flammability, Part I, Experimental

Evaluation of Flammability Parameters of Cables Using Laboratory-Scale Apparatus,” EPRI Project

RP1165-1, Factory Mutual Research Corporation, Norwood, Massachusetts, 1979.

7.11 Additional Readings

Babrauskas, V., “Burning Rates,” Section 3, Chapter 3-1, SFPE Handbook of Fire Protection

Engineering, 2 Edition, P.J. DiNenno, Editor-in-Chief, National Fire Protection Association, nd

Quincy, Massachusetts, 1995.

Babrauskas, V., “Free-Burning Fires,” Fire Safety Journal, Volume 11, page 33–51, 1986.
7-8

7.12 Problems

Example Problem 7.12-1

Problem Statement

A 32-gallon trash can exposure fire source is located 2 m (6.5 ft) beneath a horizontal cable tray.

It is assumed that the trash fire ignites an area of approximately 2 m (21 ft ) of the cable tray. 2 2

The cables in the tray are IEEE-383 unqualified and made of PE/PVC insulation material. Compute

the full-scale HRR of the PE/PVC cable insulation. The bench-scale HRR of PE/PVC is 589 kW/m .

2

Solution

Purpose:

(1) Calculate the full-scale HRR of the PE/PVC insulation material.

Assumptions:

(1) Lee’s correlation is valid for this fire scenario.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 07_Cable_HRR Calculations.xls

FDT Input Parameters: s

f

-Exposure Cable Tray Burning Area (A ) = 21 ft2

-Select Material: PE/PVC (the one with a bench-scale HRR of 589 kW/m )

2

Results*

Cable

Insulation

Full Scale HRR

kW (Btu/sec)

PE/PVC 517 (490)

*see spreadsheet on next page
7-9

Spreadsheet Calculations

FDT : 07_Cable_HRR Calculations.xls s

CHAPTER 7. ESTIMATING THE FULL-SCALE HEAT RELEASE RATE OF A 

CABLE TRAY FIRE 

Version 1805.0 

Th t• uca• •l.1tb"Htlllate 1u ntkcal: cabl! trav hatr~l:aH ta,. 

Pilrlllflt'n ln YEllOWCEllS ilr$ Bl 'r$d bj' Ult Ut U. 

Pilrlllfl t'r' In G REEII CEll S llrt AutomaUeaiiJ' h iHUd trom 1ht DROP OOVVII t.1EIIU tor Ult O.bl& h iHUd . 

. .:. IIHI:taqiUtOI1>1tt.t a iH$ al~ catU.'I'd by1U pl~<ld hHaad baad oa V<IIH$ p~ M!d II ~ " P't 

para•"&' " · n a; $preao; •Htl$ pr ~Wd aut $&CI.: to <WJotl & " " " <IH b a wroag u1tv 11 a c&ll('). 

Th c•aptH II U & II UP,~ $ •o .tl be le<t:IIWble <II <U<t\1$ ~ 1$ m <t:l&. 

INPUT PARAMETERS 

Cabl! 6uc•-scat HR R \O ~ 

ExpoHd n 'o' .:..rea (t.ugu x v·v.:tU) on m 119 Cab I: Trar ' '".) 

HEAT RELEASE RATE DATA FOR CABLE TRAY FIRE 

BEIIC H4CALE HRR Of CABLE TRAY FIRE 

Cabl! T\t)e 6uc•-scat HR R Select Ca~ e T '\lee 

pu Ualf•,or .:..rea (l x V\1

) 

a·t. ;J:\N,fll j ~ 

•:1 PE 107 1 

P EIPVC ... XPEIFRXP E ns 

P EIPVC 395 

P EIPVC 359 

XPfiii&OI>Ie I & 3Sl 

PE. PP.CI.S.PE 345 

P EIPVC 312 

PE /II >Je ~ 302 

PE. PP.CI.S.PE 299 

PE. PP.CI.S.PE 27 I 

FRXPE.C lS.Pf 258 

P E. II'{.,_IPVC, II(.H 231 

P E. 11'{.,_/PVC, II(.H 2 18 

XPE,CIS .PE 20 ! 

s n:oH . gh" bratl.asbub6 182 

XPE1XPE 178 

PE. PP.CI.S.PE 177 

s n:oH , \Ih$$ bratl 128 n.,.,. •• UHISpeclnd Va" e E•~I lt e 

ft.~IN~:·('~ ' .=i'N.('(~.=:,";"."t;.l'l\ :1' /";"It 1.'~~ ?,4{#:.:-r.« 

~ p~ Ul$0 Oick on t $I$C1Ion 
7-10

E STIMATIIIG FULL-SCALE CABLE TRAY HEAT RELEASE RATE ~~ 't<NY.~: s?P=Hmd>.-....'\ C(F)"("/>i'<:~c..-r:.:>n ~~~r(J, " adl'OO!:).\l'; Fl:\IC ;to XI. 

Q,,.: 0.46 ~a A 

mere Q,,. = cabletrayfull-scale HRR (kVll) 

Otn•= cable nybench-scale HRR (kVll) 

A= exposed 1oor area Qength x wi4h)of bumilg cable ny(m") 

Heat ~lease Rate Calculaticn 

01,.= 0.46 Ot. A 

emu¥ 

The abot@ calculations are based on princjlles developed in the SFPE Handbook of Fire Protection 

&IQineerinQ, 3ftl 6:1ition, 2002. 

C31culalions are based on cenain assurrptions and has inherent linitalions. The results of such 

calculations mayormaynot have reasonable predictit@ capabilities i:lr a given sirualion, and should 

only be interpreted by an infonned user. 

!Wlough each calculation in the spreadsheet has been veriied with the results of hand calculation, 

there is no absolute guarantee of1he accuracyoflhese calculations. 

AlyquestDns, comments, concerns. and suggestions, orto repon an error(s) in the spreadsheet, 

please send an email to nxi@lro.govormxs3@JlroQOV. 
7-11

Example Problem 7.12-2

Problem Statement

A 1.5-ft-high stack of untreated wood pallets (exposure fire source) from a recent plant modification

ignites and is located 1.5 m (5 ft) beneath a horizontal cable tray. It is assumed that the wood

pallets ignite an area of approximately 4 m (43 ft ) of the cable tray. The cables in the tray are 2 2

IEEE-383 qualified and made of PE insulation material. Compute the full-scale HRR of PE cable

insulation. The bench-scale HRR of PE material is 1,071 kW/m .

2

Solution

Purpose:

(1) Calculate the full-scale HRR of the PE insulation material.

Assumptions:

(1) Lee’s correlation is valid for this fire scenario.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 07_Cable_HRR Calculations.xls

FDT Input Parameters: s

f

-Exposure Cable Tray Burning Area (A ) = 43 ft2

-Select Material: Id PE

Results*

Cable Insulation Full Scale HRR

kW (Btu/sec)

Id PE 1,925 (1,825)

*see spreadsheet on next page
7-12

Spreadsheet Calculations

FDT : 07_Cable_HRR Calculations.xls s

CHAPTER 7. ESTIMATING THE FULL-SCALE HEAT RELEASE RATE OF A 

CABLE TRAY FIRE 

Version 1805.0 

Th t• uca• •l.1tb"Htlllate 1u ntkcal: cabl! trav hatr~l:aH ta,. 

Pilrlllflt'n ln YEllOWCEllS ilr$ Bl 'r$d bj' Ult Ut U. 

Pilrlllfl t'r' In G REEII CEll S llrt AutomaUeaiiJ' h iHUd trom 1ht DROP OOVVII t.1EIIU tor Ult O.bl& h iHUd . 

. .:. IIHI:taqiUtOI1>1tt.t a iH$ al~ catU.'I'd by1U pl~<ld hHaad baad oa V<IIH$ p~ M!d II ~ " P't 

para•"&' " · n a; $preao; •Htl$ pr ~Wd aut $&CI.: to <WJotl & " " " <IH b a wroag u1tv 11 a c&ll('). 

Th c•aptH II U & II UP,~ $ •o .tl be le<t:IIWble <II <U<t\1$ ~ 1$ m <t:l&. 

INPUT PARAMETERS 

Cabl! 6uc•-scat HR R \O ~ 

ExpoHd n 'o' .:..rea (t.ugu x v·v.:tU) on m 119 Cab I: Trar ' '".) 

HEAT RELEASE RATE DATA FOR CABLE TRAY FIRE 

BEIIC H4CALE HRR Of CABLE TRAY FIRE 

Cabl! T\t)e 6uc•-scat HR R Select Ca~ e T '\lee 

pu Ualf•,or .:..rea (l x V\1

) 

a·t. ;J:\N,fll j c~~ft ~ 

•:1 PE 107 1 

P EIPVC ... XPEIFRXP E ns 

P EIPVC 395 

P EIPVC 359 

XPfiii&OI>Ie I & 3Sl 

PE. PP.CI.S.PE 345 

P EIPVC 312 

PE /II >Je ~ 302 

PE. PP.CI.S.PE 299 

PE. PP.CI.S.PE 27 I 

FRXPE.C lS.PE 258 

P E. II'{.,_JPVC, II(.H 231 

P E. II'{.,_JPVC, II(.H 2 18 

XPE,CIS .PE 20 ! 

s n:oH . gh" bratl.asbubs 182 

XPE1XPE 178 

PE. PP.CI.S.PE 177 

s n:oH . \Ih$$ bratl 128 n.,.,. •• UHrS pec lnd Va " e E•~r lt ~ 

ft.~IN~:·('~ ' .=i'N.«~.=:,.";"."t;.l'l\ :1' /";'If 1.'~~ ?,4{#:.:-r.« 

Calculate 

~ p~ Ul~n Oick on ~c11 n 
7-13

E STIMATIIIG FULL-SCALE CABLE TRAY HEAT RELEASE RATE ~~ 't<NY.~: s?P=Hmd>.-....'\ C(F)"("/>i'<:~c..-r:.:>n ~~~r(J, " adl'OO!:).\l'; Fl:\IC ;to XI. 

Q,,.: 0.46 ~a A 

mere Q,,. = cabletrayfull-scale HRR (kVll) 

Otn•= cable nybench-scale HRR (kVll) 

A= exposed 1oor area Qength x wi4h)of bumilg cable ny(m") 

Heat ~lease Rate Calculaticn 

01,.= 0.46 Ot. A 

emu¥ 

The abot@ calculations are based on princjlles developed in the SFPE Handbook of Fire Protection 

&IQineerinQ, 3ftl 6:1ition, 2002. 

C31culalions are based on cenain assurrptions and has inherent linitalions. The results of such 

calculations mayormaynot have reasonable predictit@ capabilities i:lr a given sirualion, and should 

only be interpreted by an infonned user. 

!Wlough each calculation in the spreadsheet has been veriied with the results of hand calculation, 

there is no absolute guarantee of1he accuracyoflhese calculations. 

AlyquestDns, comments, concerns. and suggestions, orto repon an error(s) in the spreadsheet, 

please send an email to nxi@lro.govormxs3@JlroQOV. 
7-14

Example Problem 7.12-3

Problem Statement

A 3.5 ft diameter flammable liquid (lubricating oil) pool fire arises from a breach in an auxiliary

cooling water pump oil tank. The pool fire is located on the floor, 3 m (10 ft) beneath a horizontal

cable tray. It is assumed that the pool fire ignites an area of approximately 1 m (10.8 ft ) of the 2 2

cable tray. The cables in the tray are IEEE-383 unqualified and made of XPE/FRXPE insulation

material. Compute the full scale HRR of XPE/FRXPE cable insulation. The bench-scale HRR of

XPE/FRXPE is 475 kW/m .

2

Solution

Purpose:

(1) Calculate the full-scale HRR of the XPE/FRXPE insulation material.

Assumptions:

(1) Lee’s correlation is valid for this fire scenario.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 07_Cable_HRR Calculations.xls

FDT Input Parameters: s

f

-Exposure Cable Tray Burning Area (A ) = 10.8 ft2

-Select Material: XPE/FRXPE

Results*

Cable

Insulation

Full Scale HRR

kW (Btu/sec)

XPE/FRXPE 214 (203)

*see spreadsheet on next page
7-15

Spreadsheet Calculations

FDT : 07_Cable_HRR Calculations.xls s

CHAPTER 7. ESTIMATING THE FULL-SCALE HEAT RELEASE RATE OF A 

CABLE TRAY FIRE 

Version 1805.0 

Th t• uca• •l.1tb"Htlllate 1u ntkcal: cabl! trav hatr~l:aH ta,. 

Pilrlllflt'n ln YEllOWCEllS ilr$ Bl 'r$d bj' Ult Ut U. 

Pilrlllfl t'r' In G REEII CEll S llrt AutomaUeaiiJ' h iHUd trom 1ht DROP OOVVII t.1EIIU tor Ult O.bl& h iHUd . 

. .:. IIHI:taqiUtOI1>1tt.t a iH$ al~ catU.'I'd by1U pl~<ld hHaad baad oa V<IIH$ p~ M!d II ~ " P't 

para•"&' " · n a; $preao; •Htl$ pr ~Wd aut $&CI.: to <WJotl & " " " <IH b a wroag u1tv 11 a c&ll('). 

Th c•aptH II U & II UP,~ $ •o.tl be le<t:IIWble <II <U<t\1$ ~ 1$ m <t:l&. 

INPUT PARAMETERS 

Cabl! 6uc•-scat HR R \O ~ 

ExpoHd n 'o' .:..rea (t.ugu x v·v.:tU) on m 119 Cab I: Trar ' '".) 

HEAT RELEASE RATE DATA FOR CABLE TRAY FIRE 

BEIIC H4CALE HRR Of CABLE TRAY FIRE 

Cabl! T\t)e 6uc•-scat HR R Select Ca~ e T '\lee 

pu Ualf•,or .:..rea (l x V\1

) 

a·t. ;J:\N,fll j k"¢f<Pcu o ~ a·eu • .n\5! &a c:.o1 

•:1 PE 107 1 

P EIPVC ... XPEIFRXP E ns 

P EIPVC 395 

P EIPVC 359 

PE /II >Ie ~ 3Sl 

PE. PP.CI.S.PE 345 

P EIPVC 312 

PE /II >Ie ~ 302 

PE. PP.CI.S.PE 299 

PE. PP.CI.S.PE 27 I 

FRXPE.C lS.PE 258 

P E. II'{.,_IPVC, II(.H 231 

P E. II'{.,_JPVC, II(.H 2 18 

XPE,CIS .PE 20 ! 

s n:oH . gh" bratl.asbubs 182 

XPE1XPE 078 

PE. PP.CI.S.PE 077 

s n:oH . \Ih$$ bratl 128 n.,.,. •• UHrSpec lnd Va" e E•~r lt ~ 

ft.~IN~:·('~ ' .=i'N.«~.=:,.";"."t;.l'l\ :1' /";'If 1.'~~ ?,4{#:.:-r.« 

Calculate 

~ p~ Ul~n Oick on ~c11 n 
7-16

E STIMATIIIG FULL-SCALE CABLE TRAY HEAT RELEASE RATE ~~ 't<NY.~: s?P=Hmd>.-....'\ C(F)"("/>i'<:~c..-r:.:>n ~~~r(J, " adl'OO!:).\l'; Fl:\IC ;to XI. 

Q,,.: 0.46 ~a A 

mere Q,,. = cabletrayfull-scale HRR (kVll) 

Otn•= cable nybench-scale HRR (kVll) 

A= exposed 1oor area Qength x wi4h)of bumilg cable ny(m") 

Heat ~lease Rate Calculaticn 

01,.= 0.46 Ot. A 

emu¥ 

The abot@ calculations are based on princjlles developed in the SFPE Handbook of Fire Protection 

&IQineerinQ, 3ftl 6:1ition, 2002. 

C31culalions are based on cenain assurrptions and has inherent linitalions. The results of such 

calculations mayormaynot have reasonable predictit@ capabilities i:lr a given sirualion, and should 

only be interpreted by an infonned user. 

!Wlough each calculation in the spreadsheet has been veriied with the results of hand calculation, 

there is no absolute guarantee of1he accuracyoflhese calculations. 

AlyquestDns, comments, concerns. and suggestions, orto repon an error(s) in the spreadsheet, 

please send an email to nxi@lro.govormxs3@JlroQOV. 
Burnout as used in this discussion, is when all the available combustibles are consumed. 

1

It should be remembered that in most fires, the combustion will be incomplete.

8-1

CHAPTER 8. ESTIMATING BURNING DURATION

OF SOLID COMBUSTIBLES

8.1 Objectives

This chapter has the following objectives:

• Introduce factors that influence the fire duration of solid combustibles.

• Explain how to estimate fire durations for various solid combustibles.

• Approximate first order estimates of burning durations.

8.2 Introduction

The burning duration can be thought of as the time between ignition and the decay phase of a fire.

The burning duration (fire) for a given compartment size and ventilation condition is driven by the

fuel load. Fuel loading, given in terms of kg (fuel)/m or lb (fuel)/ft is based on the amount of 2 2

combustibles per unit floor area has been traditionally used to approximate the fire duration. Higher

fuel loads typically mean longer durations assuming a fire burning at a constant HRR consumes

fuel mass at a constant rate. Given the mass of material being burned per second and the amount

of material available to be consumed, it is possible to calculate a first order estimate for the total

burning duration of a fuel. Note that for ventilation-controlled fires, higher fuel loads have no effect

on compartment temperature, with the exception that the fire duration increases the gas

temperature.

8.3 Burning Duration of Solid Combustibles

Fire duration of solid combustibles is an approximation of the potential destructive impact of the

burnout of all of the available fuel in a compartment or enclosure with at least one ventilation 1

opening. The intensity and duration of a fully developed fire depend upon the amount of

combustibles available, their burning rates, and the air available to support their combustion. Fire

intensity is lower when the walls and ceiling absorb significant amounts of energy, rather than

acting primarily as insulation or radiation barriers. The possibility that the fire barriers can fail is

important to keep in mind. Long after the fully developed fire begins to decay, the fire barriers are

still being challenged. However, as in many real fire situations, this threat is usually mitigated by

automatic and/or manual fire suppression activities.
8-2

The burning duration of solid combustibles can be estimated if the HRR and total energy contained

in the fuel are known. The burning duration can be estimated from the following equation

(Buchanan, 2001):

 (8-1)

Where:

= heat release rate of the fire (kW)

E = total energy contained in the fuel (kJ)

solid t = burning duration of solid fuel (sec)

The maximum possible energy that can be released when fuel burns is the energy contained in the fuel,

E, given by the following equation:

 (8-2)

Where:

mfuel = mass of fuel (kW)

Hc = heat of combustion (kJ/kg)

Therefore, Equation (8-1) can be expressed as follows:

 (8-3)

Where:

Soild t = burning duration (sec)

mFuel = mass of solid fuel (kg)

Hc = effective heat of combustion (kJ/kg)

= heat release rate per unit floor area (kW/m )

2

AFuel = exposed floor area (length x width) of fuel (m )

2

The exposed fuel surface area (length x width) of fuel (m ) can be calculated as follows: 2

 (8-4)

Where:

AFuel = fuel surface area (m )

2

W = fuel exposed width (m)

L = fuel exposed length (m)

Table 8-1 lists the thermal properties of solid combustible materials.
8-3

Table 8-1. Thermal Properties of Common Solid Combustible Materials

(Tewarson, 1995, © SFPE. With permission.)

Materials HRR per Unit Floor Area

(kW/m )

2

Heat of Combustion

Hc

(kJkg)

PE/PVC 589 24,000

XPE/FRXPE 475 28,300

XPE/Neoprene 354 10,300

PE, Nylon/PVC, Nylon 231 9,200

Teflon 98 3,200

Douglas fir plywood 124 13,000–15,000

Fire-retardant treated plywood 81 13,500

Particle board, 19 mm thick 1,900 17,500

Nylon 6/6 1,313 32,000

Polymethlmethacrylate (PMMA) 665 26,000

Polypropylene (PP) 1,509 43,200

Polystyrene (PS) 1,101 42,000

Polyethylene (PE) 1,408 46,500

Polycarbonate 420 24,400

Polyurethene 710 45,000

Polyvinyl Chloride (PVC) Flexible 237 15,700

Strene-butadiene Copolymers (SBR) 163 44,000

Ethylene Propylene Dien Rubber 956 28,800

Empty Cartons 15 ft high 1700 12,700

Wood pallets, stacked 1.5 ft high 1,420 13,000–15,000

Wood pallets, stacked 5 ft high 3,970 13,000–15,000

Wood pallets, stacked 10 ft high 6,800 13,000–15,000
8-4

8.4 Assumptions and Limitations

The method discussed in this chapter is subject to several assumptions and limitations:

(1) Combustion is incomplete (leaving some residual fuel) and takes place entirely within the

confines of the compartment.

(2) Virtually all of the potential energy in the fuel is released in the involved compartment.

8.5 Required Input for Spreadsheet Calculations

The user must obtain the following information before using the spreadsheet:

(1) fuel type (material)

(2) mass of solid fuel (lb)

(3) exposed fuel surface area (ft )

2

8.6 Cautions

(1) Use (08_Burning_Duration_Soild.xls) spreadsheet on the CD-ROM for calculation.

(2) Make sure to enter the input parameters in the correct units.

8.7 Summary

Estimating the burning duration of solid combustibles involves the following steps:

(1) Determine the mass of fuel.

(2) Calculate the surface area of combustible solid.

(3) Calculate the burning duration using HRR per unit floor area and fuel heat of combustion.

8.8 References

Buchanan, A.H., “Structural Design for Fire Safety,” John Wiley & Sons, Limited, 2001, p. 38.

Karlsson, B., and J.G. Quintiere, Enclosure Fire Dynamics, Chapter 3, “Energy Release Rates,”

CRC Press LLC, New York, pp. 25–46, 1999.

Tewarson, A., “Generation of Heat and Chemical Compounds in Fires,” Section 3, Chapter 5, SFPE

Handbook of Fire Protection Engineering, 3 Edition, P.J. DiNenno, Editor-in-Chief, National Fire rd

Protection Association, Quincy, Massachusetts, 2002.
8-5

8.9 Problems

Example Problem 8.9-1

Problem Statement

A horizontal power cable fails as a result of self-initiated fire and burn in a compartment. Compute

the burning duration of a cable tray with an exposed surface area of 1 ft filled with 10 lb of non- 2

IEEE-383-qualified PE/PVC cables. The heat release per unit floor area of PE/PVC is 589 kW/m ,

2

and the heat of combustion is 24,000 kJ/kg.

Solution

Purpose:

(1) Calculate the burning duration of the cable material (PE/PVC).

Assumptions:

(1) Combustion is incomplete and takes place entirely within the confines of the

compartment.

(2) Virtually all of the potential energy in the fuel is released in the involved

compartment.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 08_Burning_Duration Solid.xls

FDT Input Parameters: s

solid -Mass of Solid Fuel (m ) = 10 lb

fuel -Exposure Fuel Surface Area (A ) = 1 ft2

-Select Material: PE/ PVC

Results*

Ma solid terial Burning Duration (t )

(min.)

PE/PVC 33

*see spreadsheet on next page
8-6

Spreadsheet Calculations

FDT : 08_Burning_Duration Solid.xls s

CHAPTER 8. ESDMATIIIG BURIIIIIG DURADOII OF SOUD COIYIIUSDBLES 

Versicn 1805.0 

~ Dt:tA'Itg cabU.11))1$ r.~,t '"; a a <WICdllatln OTIU bm119 <1t l.'ltln OT$Oit iCCtllbUU>h :.a>~d 11lH 

bmllg r~ wt• agiJu Hit.:.: ate a. l>.'lrnm~ten In YEllOWCELLS 11r~ Enter~d b'.' 1l$ UtU. 

P:lrnlfl$ter, ln GREEIICEllS ~~~ AUbmat call\' S$I$CUd rom 1l$ DROP COWl f,tf11Ufor 1l$ f.1 3tel1111 S&I$CUd 

:..l nb~ l• •t l1 1t au; ~ ca •h~db ~ ' P" <t:l$h~ta d l>~d au' pe d 111u • p•t 

p.1r<r1H'"· n~ pre<t: h~tt pro-.~d <nd ~ate b<rJo ero~ <IH ba wro1ge 11r>{ l1 a~ If) . n e •<~ '•• 1u ttUR ~ ' '"'•:lbe tea:ll:.e'lm a1 <uat. t ~ ma:l!. 

1.1 <10$ 01SOI:I fl el ~~ ... .) 

E)J>O$ed f bOI.:.,P.a 4-Ugli X 1.<\ft lli) OT ft e 1'6,....,) 

Heatl'l:l:a>e ~~ ~IUilf •OI.O:..I!a (O") 

E1P.C1J.I? H:at01CCtllbU1m ~ ..) 

<:;~·~-w.t~lt-~~· .. ,.....-,,.·~~ 1')1!--~ -dJ)i\~·! .V-~1:U. .ol't1 

1(,1,_,...,<1~ ....... ~.,., ...... ,_...,r;.....,,._ 00-<l C....llrll'l<*-i'!R' 

<:.-.::~ ........ 1~~ 

ii~"""lof ,',I f,{. 1io.-l..,. .... _.~ ... .t.el.b'1:""'A•;; ... ,,;...,_,~t<f<IA. tl.~, .... - .. ...t 

(;,~_.. bf(Q'A b.loo·-/.o1Piod:l_.,.,. ·~.-._ 
8-7

BURNING DURATION OF SOLID COMBUSTIBLES P,~'li 1? •o: -clliJ,UJ, . A .• "'f, :S.'Ct ii CMs..'i}~ itir ,: {,* Sil~;y. · a:vn. Pil(? 3~. 

The burning duration of a solid fuel can be calcula~d if the total energy contained in the fuel and HRR are known. 

The burning duration is given by: 

Q = E /t,ct<l 

or 

t 1ct<1= (E)/(Q" ~u~ 

Where bc1<1 = burning duration of solid combustible (sec) 

E = mh~~tlLH = total energy contained in the fuel (kJ) 

Q =heat releare rate of fire (kW) 

Q" = heat release raW per unit floor area of fuel (kWhn') 

Ah~~t =exposed floor area (length x width) of fuel(m") 

t.~= (mhtllLHc) I (Q" Ahl!t) 

Where mh~~t =mass of solid fuel (kg) 

lLHc =fuel effective heat of combustion (kJA<g) 

The above calculations are based on principles developed in the Structural Design for Fire Safe~. 2001. 

Calculations are based on certain assumptions and have inherent limitations. 

The results of such calculations may or may not have reasonable predictive capabilities for a given 

situation, and should only be in~rpreted by an informed user. 

Although each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolute Quarantee of the accuracv of these calculations. 

ArPJ questions. comments, concerns, and suggestions, or to report an euor(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or rro<:s3@nrc.gov. 
8-8

Example Problem 8.9-2

Problem Statement

A horizontal cable tray filled with non-IEEE-383 qualified XPE/FRXPE cables are ignited as a result

of overhead welding and burn in a compartment 20 ft wide x 20 ft deep x 10 ft high. The cable tray

has a nominal width of 2 ft and a linear length of 24 ft (i.e., exposed surface area of 48 ft ). 2

Compute the burning duration of XPE/FRXPE cables assuming the mass of cables is 50 lb.

The heat release per unit area of XPE/FRXPE is 475 kW/m and heat of combustion is 28,300 kJ/kg. 2

Solution

Purpose:

(1) Calculate the burning duration of the cable material (XPE/FRXPE).

Assumptions:

(1) Combustion is incomplete and takes place entirely within the confines

of the compartment.

(2) Virtually all of the heat energy in the fuel is released in the involved compartment.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 08_Burning_Duration Solid.xls

FDT Input Parameters: s

solid -Mass of Solid Fuel (m ) = 50 lb

fuel -Exposure Fuel Surface Area (A ) = 48 ft2

-Select Material: XPE/FRXPE

Results*

Ma solid terial Burning Duration (t )

(min.)

XPE/FRXPE 5

*see spreadsheet on next page
8-9

Spreadsheet Calculations

FDT : 08_Burning_Duration Solid.xls s

CHAPTER 8. ESDMATIIIG BURIIIIIG DURADOII OF SOUD COIYIIUSDBLES 

Versicn 1805.0 

~ Dt:tA'Itg cabU.11))1$ r.~,t '"; a a <WICdllatln OTIU bm119 <1t l.'ltln OT$Oit iCCtllbUU>h :.a>~d 11lH 

bmllg r~ wt• agiJu Hit.:.: ate a. l>.'lrnm~ten In YEllOWCELLS 11r~ Enter~d b'.' 1l$ UtU. 

P:lrnlfl$ter, ln GREEIICEllS ~~~ AUbmat call\' S$I$CUd rom 1l$ DROP COWl f,tf11Ufor 1l$ f.1 3tel1111 S&I$CUd 

:..l nb~ l• •t l1 1t au; ~ ca •h~db ~ ' P" <t:l$h~ta d l>~d au' pe d 111u • p•t 

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1.1 <10$ 01SOI:I fl el ~~ ... .) 

E)J>O$ed f bOI.:.,P.a 4-Ugli X 1.<\ft lli) OT ft e 1'6,....,) 

Heatl'l:l:a>e ~~ ~IUilf •OI.O:..I!a (O") 

E1P.C1J.I? H:at01CCtllbU1m ~ ..) 

<:;~·~-w.t~lt-~~· .. ,.....-,,.·~~ 1')1!--~ -dJ)i\~·! .V-~1:U. .ol't1 

1(,1,_,...,<1~ ....... ~.,., ...... ,_...,r;.....,,._ 00-<l C....llrll'l<*-i'!R' 

<:.-.::~ ........ 1~~ 

ii~"""lof ,',I f,{. 1io.-l..,. .... _.~ ... .t.el.b'1:""'A•;; ... ,,;...,_,~t<f<IA. tl.~, .... - .. ...t 

(;,~_.. bf(Q'A b.loo·-/.o1Piod:l_.,.,. ·~.-._ 
8-10

BURNING DURATION OF SOLID COMBUSTIBLES P,~'li 1? •o: -clliJ,UJ, . A .• "'f, :S.'Ct ii CMs..'i}~ itir ,: {,* Sil~;y. · a:vn. Pil(? 3~. 

The burning duration of a solid fuel can be calcula~d if the total energy contained in the fuel and HRR are known. 

The burning duration is given by: 

Q = E /t,ct<l 

or 

t 1ct<1= (E)/(Q" ~u~ 

Where bc1<1 = burning duration of solid combustible (sec) 

E = mh~~tlLH = total energy contained in the fuel (kJ) 

Q =heat releare rate of fire (kW) 

Q" = heat release raW per unit floor area of fuel (kWhn') 

Ah~~t =exposed floor area (length x width) of fuel(m") 

t.~= (mhtllLHc) I (Q" Ahl!t) 

Where mh~~t =mass of solid fuel (kg) 

lLHc =fuel effective heat of combustion (kJA<g) 

The above calculations are based on principles developed in the Structural Design for Fire Safe~. 2001. 

Calculations are based on certain assumptions and have inherent limitations. 

The results of such calculations may or may not have reasonable predictive capabilities for a given 

situation, and should only be in~rpreted by an informed user. 

Although each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolute Quarantee of the accuracv of these calculations. 

ArPJ questions. comments, concerns, and suggestions, or to report an euor(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or rro<:s3@nrc.gov. 
8-11

Example Problem 8.9-3

Problem Statement

A fire involving a 1.5-ft-high stack of wood pallets is located in a compartment 40 ft wide x 40 ft deep

x 10 ft high. The mass of the wood pallets is 30 lb. Compute the burning duration of the wood

pallet fire in the compartment. The exposed surface area of the wood pallets is 4 ft x 4 ft or 16 ft .

2

Solution

Purpose:

(1) Calculate the burning duration of the stack of wood pallets.

Assumptions:

(1) Combustion is incomplete and takes place entirely within the confines

of the compartment.

(2) Virtually all of the heat energy in the fuel is released in the involved compartment.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 08_Burning_Duration Solid.xls

FDT Input Parameters: s

solid -Mass of Solid Fuel (m ) = 30 lb

fuel -Exposure Fuel Surface Area (A ) = 16 ft2

-Select Material: Wood pallet, stacked 1.5 ft high

Results*

Ma solid terial Burning Duration (t )

(min.)

Wood pallet,

stacked 1.5 ft high

1.5

 *see spreadsheet on next page
8-12

Spreadsheet Calculations

FDT : 08_Burning_Duration Solid.xls s

CHAPTER 8. ESDMATIIIG BURIIIIIG DURADOII OF SOUD COIYIIUSDBLES 

Versicn 1805.0 

~ Dt:tA'Itg catu.10,., r.~J '"' <n " :t>re«tllatba 011u buutgdt l.'ltbt 01$0it lcctlllm U>U :.ao~d t1lH 

bmltg r~ wu agiJu HID:.: ate a. 1>.'1rnm~Ur 10 YEllOWCEllS ar~ EnUr~d b'.' tl~ U1U. P:lrnm~ten 10 GREEIICELLS ~~~ Aubmat cai!V ~cted 1" ifl 1l~ DROP COWl t.1E11Ufor 1l$ t.1 3tel1at h i$CUd 

:..l" b~ l• •t t1 tt ' <II~ ca •h~db 1U ' P" a:th~ t<nd l>~d t ' pe d 111u •p•t 

p.11<r11e'"· ~ $prea:t, hett p1 ~~d atd ~ate ba;o ero~ <IH ba w•otge t1fl{lt a~ . 

n ec•<v'•• 1u tiUR •• be tea:ll:.e1m <ual,~ t ~ma:l!. 

1.1 <10$ OfSOI:I ft el ~~ ... .) 

E)J>O$ed f bOI.:.,P.a 4-Ugli X 1.<\ft lli) OT ft e 1'6,....,) 

Heatl'l:l:a>e ~~ ~IUtlf •OI.O:..I!a (O") 

E1P.C1J.I? H:at01CCtllbU1m ~ ..) 

<:;~·~-w.t~lt-~~· .. ,.....-,,.·~~ 1')1!--~ -dJ)i\~·! .V-~1:U. .ol't1 

1(,1,_,...,<1~ ....... ~.,., ...... ,_...,r;.....,,._ 00-<l C....llrll'l<*-i'!R' 

<:.-.::~ ........ 1~~ 

ii~"""lof ,',If,{. 1io.-l..,. .... _.~ ... .t.el.b'1:""'A•;; ... ,,;...,_,~t<f<IA. tl.~, .... - .. ...t 

(;,~_.. bf(Q'A b.loo·-/.o1Piod:l_.,.,. ·~.-._ 
8-13

BURNING DURATION OF SOLID COMBUSTIBLES P,~'li 1? •o: -clliJ,UJ, . A .• "'f, :S.'Ct ii CMs..'i}~ itir ,: {,* Sil~;y. · a:vn. Pil(? 3~. 

The burning duration of a solid fuel can be calcula~d if the total energy contained in the fuel and HRR are known. 

The burning duration is given by: 

Q = E /t,ct<l 

or 

t 1ct<1= (E)/(Q" ~u~ 

Where bc1<1 = burning duration of solid combustible (sec) 

E = mh~~tlLH = total energy contained in the fuel (kJ) 

Q =heat releare rate of fire (kW) 

Q" = heat release raW per unit floor area of fuel (kWhn') 

Ah~~t =exposed floor area (length x width) of fuel(m") 

t.~= (mhtllLHc) I (Q" Ahl!t) 

Where mh~~t =mass of solid fuel (kg) 

lLHc =fuel effective heat of combustion (kJA<g) 

The above calculations are based on principles developed in the Structural Design for Fire Safe~. 2001. 

Calculations are based on certain assumptions and have inherent limitations. 

The results of such calculations may or may not have reasonable predictive capabilities for a given 

situation, and should only be in~rpreted by an informed user. 

Although each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolute Quarantee of the accuracv of these calculations. 

ArPJ questions. comments, concerns, and suggestions, or to report an euor(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or rro<:s3@nrc.gov. 

9-1

CHAPTER 9. ESTIMATING THE CENTERLINE TEMPERATURE

OF A BUOYANT FIRE PLUME

9.1 Objectives

This chapter has the following objectives:

• Discuss various types of fire plumes.

• Discuss the fire plume that is most common encountered.

• Identify the temperature and flow characteristics of the fire plume.

• Define relevant terms including fire plume, air entrainment, plume temperature, ceiling jet,

and virtual origin.

9.2 Introduction

A fire plume is a buoyantly rising column of hot combustion products, along with unburned fuel

vapor and admixed air. When fire in a building continues to grow, the plume typically impinges on

the ceiling, unless the fire remains very small or the ceiling is very high. The interaction of a plume

with a ceiling is discussed in subsequent sections.

Figure 9-1 shows a turbulent column of hot gases rising because of buoyancy differences.

The effect of the turbulence will cause rapid mixing of the hot gases with the cooler surrounding air.

The addition of cold mass to the rising column decreases its velocity, widens the column, and

reduces its temperature. When plume height is large in comparison to the width of the base of the

plume, the average midline temperature (relative to ambient temperature) is found to decrease at

a rate that 3 is inversely proportional to the height of the plume raised to the ' power. Similarly, 5

the average velocity of the midline is inversely proportional to the height of the plume raised to the

a power. Correlations have been developed to predict the temperature and velocity distribution

across a plume at any given height. These correlations are related in terms of the HRR driving the plume.

Figure 9-1 A Buoyant Turbulent Plume Showing Air Entrainment
9-2

The foregoing discussion refers to a rising column of hot gases, with no combustion taking place.

This is applicable to a fire in which the combustion occurs close to the base of the fire plume.

However, if combustion continues within the fire plume, the release of heat increases the plume

temperature and velocity. The turbulence intensity in a fire plume is high; the velocity fluctuations

at the centerline can be up to 30 percent of the average velocity, and the temperature fluctuations

can be even greater.

In general, a fire plume contains smoke particles. As surrounding air mixes into the plume, it dilutes

the smoke and reduces the temperature. This mixing is called entrainment. In order to predict

which environment a given fire will produce, it is necessary to know the rate of entrainment into the

plume. Researchers have proposed various correlations to calculate the rate of entrainment in a

fire plume, however, the results are not entirely reliable. Small ambient distribution in the air near

the plume can also have substantial effects on the entrainment rate. When combustion occurs only

in the lower portion of a plume, there is roughly an order of magnitude more entrained air present

than the stoichiometric requirement at the plume height above when there is no combustion

occurring.

A fire plume can be subdivided into flaming (reacting) and non-flaming (non-reacting) zones.

The flaming zone lies just above the fire source and the fuel vapors released by the combustibles

burn in this zone. The air required by the reaction is supplied by the entrainment attributable to the

upward movement of the reactants. Above the flaming zone where no reaction is taking place

in the column of hot products of combustion is defined as the non-flaming zone.

9.3 Fire Plume Characteristics

Fire plumes can be characterized into various groups, depending on the scenario under

investigation. This chapter focuses on the point source thermal plume, which is the plume most

commonly encountered in fire dynamics applications. The point source thermal plume

(or axisymmetric buoyant plume), as described by George, Alpert, and Tamanini (1977) and Alpert

and Ward (1984), results when a diffusion flame is formed above the burning fuel. An axis of

symmetry is assumed to exist along the vertical centerline of the plume. Another fire plume

category, known as the line plume, is caused by a diffusion flame formed above a long and narrow

burner that allows air to be entrained from two sides as the hot gases rise. Examples of line fires

including flame spread over flammable wall linings, a balcony spill plume, a long sofa, a row of

townhouses, and the advancing front of forest fire.

The unconfined axisymmetric plume has no physical barriers to limit vertical movement or restrict

air entrainment across the plume boundary. In a confined space the fire plume can be influenced

by surrounding surfaces. For example, the area through which air may be entrained is reduced

if an item is burning against a wall. Similarly, if the fire plume impinges on a ceiling, it will be

deflected horizontally to form a ceiling jet. Impingement on a ceiling also reduces the amount of

air entrained by the plume. The most important consequence of plumes interacting with their

surroundings is heat transfer to the surfaces involved and the speed at which these surfaces

(if combustible) will ignite and contribute to the fire growth process.
9-3

The axisymmetric fire plume is conventionally divided into three zones, as shown in Figure 9-2.

In the continuous flame zone, the upward velocity is near zero at the base and increases with

height. In the intermittent flame zone the velocity is relatively constant, while in the far field zone

the velocity decreases with height.

Figure 9-2 Three Zones of the Axisymmetric Buoyant Fire Plume

The quantity of air entrained, along with a resultant decrease in plume temperature and increase

in the total mass transported in the plume, are governed by the plume velocity and entrainment

coefficient. The entrained flow is proportional to the plume velocity at a particular elevation. This

proportional constant is the entrainment coefficient. Hence, the amount of air entrained is related

to the plume velocity multiplied by the entrainment coefficient.
9-4

Temperature, velocity, and mass flow rates of the fire plume above the flame are critical to

the many technical aspects of fire growth in a compartment, including the following examples:

• the rate of formation and descent of the smoke layer

• the temperature and concentration of the hot smoke layer

• the required size of the smoke and heat venting systems

• the actuation time of sprinklers and detectors

9.3.1 Plume Temperature

The peak temperature is found in the plume centerline, and decreases toward the edge of the

plume where more ambient air is entrained to cool the plume. The centerline temperature, denoted

Tp(centerline), varies with height. In the continuous flame region, for example, the centerline

temperature is roughly constant and represents the mean flame temperature. By contrast, the

temperature decreases sharply above the flames as an increasing amount of ambient air is

en p(centerline) trained into the plume. The symbol T describes the increase in centerline plume

a

temperature above the ambient temperature, T , as shown in the following equation:

 (9-1)

Numerous correlations are available to estimate the plume centerline temperature. These

correlations relate the temperature as a function of HRR and of height above the source.

For example, consider a region of a ceiling jet at radial distance from the fire axis equal to the

vertical distance from the fire source to the ceiling. In this region, the maximum velocity in the jet

drops to half the value near the fire axis, and the temperature (relative to ambient) drops to about

40 percent of the value near the fire axis. The maximum velocity and temperature exist at a distance

below the ceiling equal to about 1-percent of the distance from the fire source to the ceiling. If the

walls are much farther away than this, the temperature and velocity of the ceiling jet decay to

negligibly low values before the jet encounters the nearest wall. However, if the nearest wall is not

far away, a reflection occurs when the jet reaches the wall, and the reflected jet moves back toward

the fire axis just under the original jet. Thus, the hot layer under the ceiling becomes thicker.

If the compartment has an opening and fire continues, the hot layer ultimately becomes thick

enough to extend below the top of the opening, after which the hot, smoke-laden gases begin

to exit from the compartment.
9-5

Heskestad (1995) provided a simple correlation for estimating the maximum centerline temperature

of a fire plume as a function of ceiling height and HRR:

 (9-2)

Where:

Tp(centerline) = plume centerline temperature (K)

Ta = ambient air temperature (K)

= convective HRR (kW)

g = acceleration of gravity (m/sec )

2

p

c = specific heat of air (kJ/Kg-K)

a

 = ambient air density (kg/m )

3

z = elevation above the fire source (m)

0

z = hypothetical virtual origin of the fire (m)

The virtual origin is the equivalent point source height of a finite area fire (Figure 9-3). The location

of the virtual origin is needed to calculate the thermal plume temperature for fires that originate in

an area heat source. The thermal plume calculations are based on the assumption that the plume

originates in a point heat source. Area heat sources include pool fires and burning threedimensional objects such as cabinets and cable trays. The use of a point heat source model for

area sources is accomplished by calculating the thermal plume parameters at the virtual point

source elevation, rather than the actual area source elevation.

Figure 9-3 Fire Plume with Virtual Origin
9-6

The v 0irtual origin, z , depends on the diameter of the fire source and the total energy released,

as follows:

 (9-3)

Where:

0

z = virtual origin (m)

D = diameter of fire source (m)

= total HRR (kW)

For non-circular pools, the effective diameter is defined as the diameter of a circular pool

with an area equal to the actual area given by the following equation:

 (9-4)

Where:

D = diameter of the fire (m)

Af = fuel spill area or curb area (m )

2

Total HRR is used when calculating the mean flame height and position of the virtual origin.

However, the convective HRR is used when estimating other plume properties, since this is the

part of the energy release rate that causes buoyancy. The energy losses attributable to radiation

from the flame are typically on the order of 20 to 40 percent of the total HRR . The higher of

these values is valid for the sootier and more luminous flames, often from fuels that burn with a low

combustion efficiency. The convective HRR is, therefore, often in the range 0.6 to 0.8 where

is the total HRR.
9-7

9.4 Application for Centerline Fire Plume Correlation

The centerline temperature correlation can be used to predict the temperature increase of the

structural elements and subsequent failure of the compartment structure. Also, thermal plume

temperature may be used to estimate the temperature of a target located above the plume.

As previously discussed, it is common for a fire plume impinging on a ceiling to make a 90-degree

turn and spread out readily under the ceiling, thereby forming a ceiling jet. This ceiling jet

is important for two reasons:

(1) Devices to detect the fire, as well as automatic sprinklers, are generally mounted right under

the ceiling. Knowledge of the time of arrival and properties of the ceiling jet are crucial to

predict when a device will actuate. The actuation of devices, (e.g., sprinklers smoke and

thermal detectors) are discussed in Chapters 10, 11, and 12.

(2) The downward thermal radiation from the ceiling jet (including a small fraction from the hot

ceiling itself) is a major factor in preheating and igniting combustible items that are not yet

involved in the fire. This radiation is very important in determining the rate of fire spread.

9.5 Assumptions and Limitations

The methods discussed in this chapter are subject to several assumptions and limitations.

(1) All heat energy is released at a point.

(2) The correlation was developed for two-dimensional area sources.

(3) If the surrounding air is at an elevated temperature, the temperature difference between the

plume and the surrounding environment is small. In this situation, the thermal plume cools

less effectively, so Equation 9-2 will underestimate the temperature.

(4) The thermal plume equation is not valid when the momentum forces in a plume are more

significant than the buoyant forces, as in a jet fire. If this type of situation is encountered,

specialized calculation approaches should be used.

9.6 Required Input for Spreadsheet Calculations

The user must obtain the following information before using the spreadsheet:

(1) heat release rate of the fire (kW)

(2) distance from the top of the fuel to the ceiling (ft)

(3) surface area of the combustible fuel (ft )

2
9-8

9.7 Cautions

(1) Use (09_Plume_Temperature_Calculations.xls) spreadsheet in the CD-ROM for calculation.

(2) Make sure to use correct units when entering the input parameters.

9.8 Summary

This chapter discusses fire plume and ceiling jet flow concepts and related fire hazard calculations.

The region of hot gas that flows above the flame is called a plume. The plume changes in

temperature, velocity, and diameter primarily because surrounding air is entrained (or mixed) into

the upward plume flow. This entrained air reduces the plume temperature and increases the width

of the plume. The total flow of the gases increases rapidly high above the flame. The plume

temperature and combustion product concentrations are highest just above the flame. Moving

upward, the temperature decreases because the cooler entrained air from the surrounding

environment is mixed with the hot plume gas flow. The concentration of combustion products is

also reduced.

Estimating the centerline temperature of a fire plume involves the following steps:

(1) Calculate the diameter of the fire.

(2) Calculate the virtual origin of the fire.

(3) Calculate the convective HRR.

p(centerline) (4) Calculate the plume centerline temperature T .
9-9

9.9 References

Alpert, R.L., and E.J. Ward, “Evaluation of Unsprinklered Fire Hazard,” Fire Safety Journal, Volume 7,

No. 177, 1984.

Heskestad, G., “Fire Plumes,” Section 2, Chapter 2, SFPE Handbook of Fire Protection

Engineering, 2 Edition, P.J. DiNenno, Editor-in-Chief, National Fire Protection Association, nd

Quincy, Massachusetts, 1995.

George, W.K., R.L. Alpert and F. Tamanini, “Turbulence Measurements in an Axisymmetric

Buoyant Plume,” International Journal of Heat Mass Transfer, Volume 20, pp.1145–1154, 1977.

9.10 Additional Readings

Drysdale, D.D., An Introduction to Fire Dynamics, Chapter 4, “Diffusion Flames and Fire Plumes,”

2 Edition, John Wiley and Sons, New York, 1998. nd

Fire Dynamics, Course Guide, Federal Emergency Management Agency (FEMA), United States

Fire Administration (USFA), National Emergency Training Center, Emmitsburg, Maryland, 1995.

Friedman, R., Principle of Fire Protection Chemistry and Physics, 3 Edition, National Fire rd

Protection Association, Quincy, Massachusetts, 1998.

Karlsson, B., and J.G. Quintiere, Enclosure Fire Dynamics, Chapter 4, “Fire Plumes and Flame

Heights,” CRC Press LLC, New York, pp. 181–225, 1999.

Quintiere, J.G., Principles of Fire Behavior, Delmar Publishers, Albany, New York, 1997.
9-10

9.11 Problems

Example Problem 9.11-1

Problem Statement

A steel beam is located 25 ft above the floor. Calculate the temperature of the beam exposed

from a 34.5 ft lube oil pool fire. Assume the HRR of the fire is 5,000 kW.

2

Solution

Purpose:

(1) Determine the plume centerline temperature for the pool fire scenario.

Assumptions:

(1) All heat is released at a point.

(2) Buoyant forces are more significant than momentum forces.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 09_Plume_Temperature_Calculations.xls

FDT Input Parameters: s

-Heat Release Rate = 5,000 kW

-Distance from the Top of the Fuel to the Ceiling (z) = 25 ft

c

-Area of Combustible Fuel (A ) = 34.5 ft2

Results*

Heat Release

Rate (kW)

Plume Centerline

Tempe p(centerline) rature (T )

°C (°F)

5,000 244 (471)

*see spreadsheet on next page
9-11

Spreadsheet Calculations

FDT : 09_Plume_Temperature_Calculations.xls s

CHAPTER 9. ESTIMATING CENTERLINE TEMPERAlURE OF A 

BUOYANTFIRE PLUME 

Version1805.0 

The bllowing calculations estimat»llhe cent»lr1ine plumetemper.rrure in a compartment fire. 

Parameters shoUd be specified ONLY IN THE YELLOW INPUT PARA METER BOXES. 

All subsequent OU1PUl wlues are calculated bythe spreadsheet and based on \Glues specif»ld in the input 

parameters. This spreadsheet is protected and secoreto avoid errors due to a wrong envy in a cell(s). 

The chapter in the NUREG should be read bei:lre an analysis is made. 

INPUT PARAMETERS 

~at ~lease Rate ofthe Fire (Q) 5000.00 t w 

• • 

Be\Gtion #tlo'W the Fire Source (z) 

.A"ea of Combuslible Fuel (A.) 

.Pmbient ~r T empemure (T,.) 

AMBIENT CONDITIONS 

Speci'c Heat of Air (c.,) 

.Pmbient Air Oensity(p,.) 

.A::celemion of Gra\ity(g) 

Convective Heat Release Fraction (1 ) 

25.00 

34.50 

77.00 ° 

Calculate 

1.00 •:J,t;g-K 

1.18 t;glhl 

9.81 hl · 

0.70 

tbte: Pirdensitywill autom31icallycorrect with Anbient Pir Tempemure (T,.) Input 

E STIMA TIIIG PLUIYI: CE filE RUIIE TEIYI'E RATURE ~~,, ,.,~~ : s.=P=Htm::>«>. 'IFI <~"I"r«~"Tbr. =n;..r.~r~ 3 " :«", :l.'\l'::, !"~ . 

T11 .. .,.,,.,.,,. T .. = 9.1 (T~ C11:t ~ Q,.:b-:. (z • zu)-o-:. 

\Aihere T11'"'"'""""''= plume center1ine ttlmper.nure ("C) 

QL = con\@ctitte portion of the heat release r.ne (kVll) 

T .. = ambient air ltlmper.nure (K) 

Q = acceler.nion ofQra\itv(mJsec:t) 

c., = speci1ic heat ofai" (kJA<g·K) 

p .• = ambient air density (kg.tn :.) 

z = dimnce tom1he top ofthe tiel pac!Gge to the ceiling (m) 

zu = hwothetical \Bnual origin ofthe fire (m) 

Convective Heat ~lease Rate C<llculaticn 

0 .. = ~ Q 

Where Q,. = COn\@Cii\@ portion of the heat release r.rte (kVl/) 

Q = heat release r.n:e ofthe fire (kVV) 

1 .. = conttective heat release fraction 

0. = 3500 kW 

Are Diameter C<llcUaticn 

A.= "O:t/4 

Where 

0= >(4A."') 

, A.= area ofcorrbustible fuel (m) 

0 =fire diameter (m) 

0= 2.02 m 

Hl,lpothfrtical \Artual Orit=~in CalcUation 

w O = ·1.02 + 0.083 (O:b)ro 

Where 

zu..O= 

zo= 

zu = \irtual orQin ofthe fire (m) 

Q =heat release r.n:e of fire (kVll) 

0 =fire diameter (m) 

0.22 

0.44m 
9-12

Cet«erline Phn.e T etll)er.tture Ullt ulation 

T J> ~niNI~ T ~ = 9.1 (T Jg C1> z P~ l'0 Q c z>) (Z- ZD) -$.') 

T J> ~niNI,_ T ~= 218.97 

T J> ~niNI~) = 516.97 K 

The above calrulations are based on principles developed in the SFP E Handlxlok of Fire 

Protection E naineerina. 3f4 Edition, 2002. 

Calrulations are based on certain assumptions and have inherent limitations. The results of such 

calrulations may or may not have reasonable predictive capabilities for a given situation, and 

should only be interpreted by an informed user. 

Mhough each calculation in the spreadsheet has been veri1ied Wth the results of hand calculation, 

there is no absolute guarantee of the aa:uracy of these calrulations. 

Mv auestions, comments, concems, and suaaestions, or to report an error( s) in the soreadsheet, 

please send an email to nxi@nrc.gov or mxs3@nrc.gov. 
9-13

Example Problem 9.11-2

Problem Statement

Estimate the maximum plume temperature at the ceiling of an 8-ft-high room above a 1,000-kW

trash fire with an area of 10 ft . Assume that the ambient air temperature is 77 °F. 2

Solution

Purpose:

(1) Determine the maximum plume centerline temperature for the transient combustible

fire scenario.

Assumptions:

(1) All heat is released at a point.

(2) Buoyant forces are more significant than momentum forces.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 09_Plume_Temperature_Calculations.xls

FDT Input Parameters: s

-Heat Release Rate = 1000 kW

-Distance from the Top of the Fuel to the Ceiling (z) = 8 ft

c

-Area of Combustible Fuel (A ) = 10 ft2

Results*

Heat Release Rate

(kW)

Plume Centerline

Tempe p(centerline) rature (T )

°C (°F)

1,000 549 (1021)

*see spreadsheet on next page
9-14

Spreadsheet Calculations

FDT : 09_Plume_Temperature_Calculations.xls s

CHAPTER 9. ESTIMATING CENTERLINE TEMPERAlURE OF A 

BUOYANTFIRE PLUME 

Version1805.0 

The bllowing calculations estimat»llhe cent»lr1ine plumetemper.rrure in a compartment fire. 

Parameters shoUd be specified ONLY IN THE YELLOW INPUT PARA METER BOXES. 

All subsequent OU1PUl wlues are calculated bythe spreadsheet and based on \Glues specif»ld in the input 

parameters. This spreadsheet is protected and secoreto avoid errors due to a wrong envy in a cell(s). 

The chapter in the NUREG should be read bei:lre an analysis is made. 

INPUT PARAMETERS 

~at ~lease Rate ofthe Fire (Q) 1000.00 t w 

• • 

Be\Gtion #tlo'W the Fire Source (z) 

.A"ea of Combuslible Fuel (A.) 

.Pmbient ~r T empemure (T,.) 

AM B1ENT CON01T10NS 

Speci'c Heat of Air (c.,) 

.Pmbient Air Oensity(p,.) 

.A::celemion of Gra\ity(g) 

Convective Heat Release Fraction (1 ) 

8.00 

10.00 

77.00 ° 

Calculate 

1.00 •:J,t;g-K 

1.18 t;glhl 

9.81 hl · 

0.70 

tbte: Pirdensitywill autom31icallycorrect with Anbient Pir Tempemure (T,.) Input 

E STIMA TIIIG PLUIYI: CE filE RUIIE TEIYI'E RATURE ~~,, ,.,~~ : s.=P=Htm::>«>. 'IFI <~"I"r«~"Tbr. =n;..r.~r~ 3 " :«", :l.'\l'::, !"~ . 

T11 .. .,.,,.,.,,. T .. = 9.1 (T~ C11:t ~ ,.:b~ (z · -o~ 

\Aihere T11'"'"'""""''= plume center1ine ttlmper.nure ("C) 

QL = con\@ctitte portion of the heat release r.ne (kVll) 

T .. = ambient air ttlmper.nure (K) 

Q = acceler.nion ofQra\itv(mJsec:t) 

c., = speci1ic heat ofai" (kJA<g·K) 

p .• = ambient air density (kg.tn :.) 

z = dimnce tom1he top ofthe tiel pac!Gge to the ceiling (m) 

zu = hwothetical \Bnual origin ofthe fire (m) 

Convective Heat ~lease Rate C<llculaticn 

0 .. = ~ Q 

Where Q,. = COn\@Cii\@ portion of the heat release r.rte (kVl/) 

Q = heat release m:e ofthe fire (kVV) 

1 .. = conttective heat release fraction 

0. = 700 kW 

Are Diameter C<llcUaticn 

A.= "O:t/4 

Where 

0= >(4A."') 

, A.= area ofcorrbustible fuel (m) 

0 =fire diameter (m) 

0= 1.09 m 

Hl,lpothfrtical \Artual Orit=~in CalcUation 

w O = ·1.02 + 0.083 (O:b)ro 

Where 

zu..O= 

zo= 

zu = \irtual orQin ofthe fire (m) 

Q =heat release m:e of fire (kVll) 

0 =fire diameter (m) 

0.19 

0.21 m 
9-15

Cet«erline Phn.e T etll)er.tture Ullt ulation 

T J> ~niNI~ T ~ = 9.1 (T Jg C1> z P~ l'0 Q c z>) (Z- ZD) -$.') 

T J> ~niNI,_ T ~= 524.40 

T J> ~niNI~) = 822.40 K 

The above calrulations are based on principles developed in the SFP E Handlxlok of Fire 

Protection E naineerina. 3f4 Edition, 2002. 

Calrulations are based on certain assumptions and have inherent limitations. The results of such 

calrulations may or may not have reasonable predictive capabilities for a given situation, and 

should only be interpreted by an informed user. 

Mhough each calculation in the spreadsheet has been veri1ied Wth the results of hand calculation, 

there is no absolute guarantee of the aa:uracy of these calrulations. 

Mv auestions, comments, concems, and suaaestions, or to report an error( s) in the soreadsheet, 

please send an email to nxi@nrc.gov or mxs3@nrc.gov. 

10-1

CHAPTER 10. ESTIMATING SPRINKLER RESPONSE TIME

10.1 Objectives

This chapter has the following objectives:

• Explain the advantages and disadvantages of sprinklers.

• Identify the four basic types of sprinkler systems.

• Describe the purpose of sprinklers.

• Explain how sprinklers function.

10.2 Introduction

Sprinklers are manufactured in a variety of temperature ratings and orifice sizes. In selecting

sprinkler systems, one must carefully consider the potential fire hazard, ceiling configuration,

corrosiveness of the environment, susceptibility to damage, etc. Every situation must be thoroughly

analyzed to choose the best type of sprinkler system for a given hazard.

Sprinklers produce a cooling effect on the fire when the water from a sprinkler vaporizes to cool the

burning materials below their ignition temperature. Sprinklers are designed to control a fire.

However, many times the sprinkler system extinguishes the fire because the surrounding materials

can no longer heat to their ignition temperature. If the first sprinkler cannot control the fire,

a second sprinkler is activated which provides additional cooling. This process continues until the

fire is controlled. Sprinklers are reliable thermosensitive devices, they rarely fail, are cost effective,

and typically use less water than fire hoses. This helps reduce the amount of equipment damage

by applying water directly over the fire. Human response time (i.e., discovery of the fire, travel time

by the fire brigade) usually takes much longer than the time required for automatic sprinklers to

control a fire while it is still in the early stages. This also reduces the amount of time available for

smoke to be produced and damage equipment.

There are four basic types of automatic sprinkler systems. Within these four basic categories,

sprinkler systems can be further classified according to the hazard they protect (such as ordinary

hazard or in-rack exposure protection), additives to the system (such as antifreeze or foam), or

special connection to the system (such as multipurpose piping). Despite these various

classifications, sprinkler systems can still be categorized as one of the following four basic types:

• The automatic wet pipe sprinkler system is the most prevalent type because it is

permanently charged with water, meaning that it is always ready for a fire. When the fusible

element of the sprinkler reaches its predetermined temperature, it activates and water flows

out of the orifice toward the deflector, causing the water to finely spray on the burning

combustibles. An alarm check valve is installed where the water initially enters from the

supply source. That valve has fittings to permit the connection of both local and remote

location alarms. It also acts as a “check valve,” permitting water to flow only toward the

sprinkler. The disadvantage of the wet pipe sprinkler system is that they are not suitable

for automatic fire protection in unheated buildings, and should a sprinkler be broken from

the piping or a pipe or fitting fail, water will be discharged on to building contents that may

be susceptible to water damage.
10-2

• The automatic dry pipe sprinkler system is similar to the automatic wet pipe system, with

the exception that the water in wet pipe system is replaced by compressed air (or nitrogen)

and the alarm check valve is replaced by a dry pipe valve. Compressed air holds the dry

pipe valve shut, thereby preventing water from entering the system. When a sprinkler

activates the air is released, and the water pressure from the supply system opens the dry

pipe valve. Water then enters the system, fills the piping, and is discharge by the open

sprinkler. The use of a dry pipe sprinkler is subject to many limitations. They should only

be used in low-temperature areas because of (1) delay time from releasing the compressed

air to water availability and (2) internal pipe corrosion and tuberculation from alternating wet

and dry periods.

• The deluge system simultaneously discharges water from every open sprinkler on the

system. There are no fusible elements in the sprinklers or spray nozzles to hold back the

water. The system turns on when a “deluge” valve at the water supply side automatically

opens. The system is typically actuated by heat detectors mounted above the open

sprinklers. Most deluge systems can also be manually actuated. One disadvantage to this

system is water damage can be extensive because of the amount of water that is used with

all of the open sprinklers.

• The pre-action system is similar to a deluge system with closed heads. Before the water

can be released, two conditions must be satisfied. First, the fusible element of the sprinkler

must be activated and, second the detector must open the deluge valve. The advantage

to this system is that it reduces the amount of accidental discharge to water-sensitive

equipment. The disadvantage is that the system is more expensive and complicated than

an automatic wet pipe system.

The effectiveness of a sprinkler installation depends on many factors. Some factors are

characteristics of the system itself, such as the thermal rating and spacing of the sprinklers, the

depth at which the individual sprinklers are mounted below the ceiling, and their pressure and flow

characteristics. Other factors are characteristics of the building or compartment in which the

system is installed. Compartment characteristics include the height of the ceiling; the area of the

compartment; and the presence of openings, joists, or ventilation currents at the ceiling level, which

can affect the flow of hot gases. Still other factors depend upon the type of fire load in the

compartment, such as the type of combustible and the closeness and height of its stacking, which

can affect both the rate of fire development and the ability of the sprinkler system to control the fire.

As previously stated, sprinklers are the most reliable thermosensitive devices, but many factors can

cause them to fail, including a lack of available water caused by a closed water supply valve; a

broken water supply header; or an empty water tank. A fire pump could also fail to start

automatically. If the pump is driven by an electric motor, such pump failures could result from a

power failure. If the pump is driven by a diesel engine, pump failures could result from poor

maintenance, dead batteries, or a lack of fuel. Other causes of failure could include shutting down

for maintenance or repairs, allowing unusual items to enter water mains, corrosion or tuberculation

in the sprinkler piping, corroded or painted sprinkler heads, partial sprinklers, combustible

overloading, or an inadequate water supply.
10-3

Sprinkler technology is changing fast. The installation requirements for the common types of

sprinklers are discussed in NFPA 13. Newer sprinklers that are not covered in NFPA 13 must be

installed in accordance with their specific listing requirements.

There are three basic installation configurations of sprinklers (upright, pendant, and sidewall) and

a number of different variations of the three. Within these three basic types of sprinklers, there are

a number of different kinds of sprinklers:

• Spray sprinkler

• Conventional sprinkler

• Fast-response sprinkler

• Residential sprinkler

• Extended coverage sprinkler

• Quick-response sprinkler

• Quick-response extended coverage

sprinkler

• Large-drop sprinkler

• Early suppression fast response

(ESFR) sprinkler

• Open sprinkler

• Special sprinkler

• Specific application sprinkler

• Flush sprinkler

• Concealed sprinkler

• Recessed sprinkler

• Corrosion-resistant sprinkler

• In-rack sprinkler

• Dry sprinkler

The ESFR sprinkler is one of the newer sprinklers being widely used for high challenge fires.

Unlike other sprinklers that are designed only to control fires, the ESFR is designed with a fast

response, large water droplet size, and the velocity to extinguish a high-challenge fire. As a result,

very strict design and installation requirements must be followed when using an ESFR sprinkler.

The extended coverage sprinkler is another relatively new sprinkler technology. This usually

reduces the number of required branch lines, thereby decreasing the cost of the system.

10.3 Operating Principles of Automatic Sprinklers

The two main functions of an automatic sprinkler system are to (1) detect a fire and (2) control it

or prevent its growth. Automatic sprinklers are installed to protect property and occupants, give

warning of fire existence and control only in burning areas.

The most common sprinklers have either a soldered metallic element or a liquid-filled bulb.

The NFPA Handbook, 18 Edition, defines fusible sprinklers as common fusible-style automatic th

sprinklers that operate when a metal alloy of a predetermined melting point fuses. Various

combinations of levers, struts, and links or other soldered members are used to reduce the force

acting upon the solder so that the sprinkler is held closed with the smallest practical amount of

metal and solder. This minimizes the time of operation by reducing the mass of fusible metal to be

heated. The solders used with the automatic sprinklers are alloys of optimum fusibility composed

primarily of tin, lead cadmium, and bismuth, which all have sharply defined melting points. Although

an individual metal may have a low melting point, an alloy that includes that metal may have a lower

melting point. The mixture of two or more metals that gives the lowest possible melting point

is called a eutectic alloy.
10-4

Bulb sprinklers are a second style of operating element. Such sprinklers use a process in which

heat causes the liquid in the bulb to expand and shatter the bulb at a predetermined temperature.

This releases a seal valve and allows water to be sprayed onto the burning materials by the

deflector. The predetermined temperature can be changed by adjusting the type and amount of

liquid in the bulb. Bulb sprinklers are the most stable against atmospheric corrosion.

Other styles of thermosensitive operating elements that may be employed to provide automatic

discharge include bimetallic discs, fusible alloy pellets, and chemical pellets.

10.3.1 Heat Transfer Characteristics for Heat-Sensitive Elements

Figure 10-1 schematically illustrates the fundamental heat transfer characteristics for the heatsensitive element of the sprinkler. Conduction from the heated gas, convection from the heated

gas, and radiation from the fire combine to transfer heat to the fusible element. Heat is always

transferred away from the element by conduction to its supporting structure. Heat-sensitive

elements are generally not perfectly insulated from other components of the sprinkler. The link

mechanism holds the sprinkler closed and finite thermal resistance permits heat flow from the

element. The quantity versus time history for the difference between the in-flow and out-flow of

heat determines the time for the element to reach its operating temperature.

Figure 10-1 Heat Transfer Characteristics of the Heat-Sensitive Element of a Sprinkler
10-5

10.3.2 Sprinkler Dynamics

Figure 10-2 shows how the mechanical force exists in a solder-type link-and-lever-style automatic

sprinkler. The construction shown is diagrammatic and does not represent any particular sprinkler.

This figure is reproduced from the NFPA Handbook, 18 Edition (Isman, 1997). th

Figure 10-2 Representative Arrangement 

of a Solder-Type Link-and-Lever Automatic Sprinkler

(Adapted from NFPA Handbook 18 Edition, 1997 with permission) th

The mechanical force normally exerted on the top of the cap or valve is many times that developed

by the water pressure below, so that the possibility of leakage, even from water hammer or

exceptionally high pressure, is practically eliminated. The mechanical force in a link-and-lever

sprinkler is produced by tension in the sprinkler frame, usually created by tightening the screw that

holds the deflector down against the toggle joint formed by the levers. This pressure is applied

against the valve or cap, but the line of force is not direct. The eccentricity of the loading permits

a leveraged reduction of the force, first by the toggle effect of the two levers, and second by the

mechanism of the link parts. The force resisted by the solder is made relatively low because solder

of the composition needed to give the desired operating temperatures is subject to cold flow under

high stress. The sprinkler frame or other parts usually posses a degree of elasticity to provide the

energy that produces a positive, sharp release of the operating parts.

To ensure that cold flow will not be a problem, the laboratories that test and list sprinklers use

statistical methods to simulate long-term loading of heat-responsive elements. Statistical methods

are also employed to ensure that the crush strength of glass bulbs is sufficiently higher than the

frame loads that will be applied to the bulbs.
10-6

10.3.3 Temperature Ratings of Automatic Sprinklers

Automatic sprinklers have various temperature ratings that are based on the UL standardized test

(Operating temperature (bath) test) in which a sprinkler is immersed in a liquid and temperature of

the liquid is raised very slowly until the sprinkler operates. In the bath test, an automatic sprinkler

operates within a range having a maximum temperature not to excess of either 5 °C (10 °F) or

107 percent of the minimum temperature of the range, whichever is greater. For the purpose of this

determination, the marked temperature rating is to be included as one of the values within the

range, making a total of eleven values in the range. Water is to be used in bath tests of sprinklers

that have operating temperature ratings of 79 °C (175 °F) or lower. Samples having operating

temperature ratings of 80–302 °C (176–575 °F) are to be bath-tested in an oil having a flash point

exceeding the test temperature (Bryan, 1990).

General sprinkler ratings are given in Table 10-1, based on the NFPA 13, “Standard for Installation

of Sprinkler Systems.”

Table 10-1. Temperature Ratings, Classification, and Color Coding of Automatic Sprinklers

Maximum

Ceiling

Temperature

°C (°F)

Temperature Rating

°C (°F)

Temperature

Classification

Color Code Glass Bulb Color

38 (100) 57–77

(135–170)

Ordinary Uncolored or

black

Orange or red

66 (150) 79–107

(175–225)

Intermediate White Yellow or green

107 (225) 121–149

(250–300)

High Blue Blue

149 (300) 163–191

(325–375)

Extra high Red Purple

191 (375) 204–246

(400–475)

Very extra high Green Black

246 (475) 260–302

(500–575)

Ultra high Orange Black

329 (625) 343 (650) Ultra high Orange Black
10-7

The temperature rating of each fusible-element-style automatic sprinkler is typically stamped on the

soldered link. For bulb sprinklers, the temperature rating must be stamped or cast on some visible

part of the sprinkler such as the deflector. Color codes are also used for glass bulbs and frame

arms of fusible-element sprinklers. In addition, the recommended maximum room temperature is

restricted for both bulbs and fusible-element sprinklers because fusible-element begins to lose its

strength somewhat below its actual melting point. Premature operation of a solder sprinkler

usually depends on the extent to which the normal room temperature is exceeded, the duration of

the excessive temperature, and the load on the operating parts of the sprinkler. While glass bulb

sprinklers do not lose strength at temperatures close to their operating temperatures, using them

at such temperatures can result in continuous loss and reforming of the air bubble, which creates

stresses on the bulb (NFPA Handbook, 18 Edition, 1997). Table 10-2 provides temperature th

ratings for sprinklers.

Tab activation le 10-2. Generic Sprinkler Temperature Rating (T )

Temperature Classification Range of Temperature Ratings

°C (°F)

Generic Temperature Ratings

°C (°F)

Ordinary 57–77 (135–170) 74 (165)

Intermediate 79–107 (175–225) 100 (212)

High 121–149 (250–300) 135 (275)

Extra high 163–191 (325–375) 177 (350)

Very extra high 204–246 (400–475) 232 (450)

Ultra high 260–302 (500–575) 288 (550)

Ultra high 343 (650) 288 (550)

The concept of a response time index (RTI) was developed by Factory Mutual Research

Corporation (FMRC) to be a fundamental measure of thermal sprinkler sensitivity. A sprinkler’s RTI

is determined in plunge tests with a uniform gas flow of constant temperature and velocity and can

be used to predict the sprinkler’s activation time in a fire environment. The RTI was developed

under the assumption that conductive heat exchange between the sensing element and supportive

parts is negligible. The RTI is a function of the time constant, , of the sprinkler which is related to

the mass and surface area of the sprinkler thermal element. Faster sprinklers have low RTIs and

smaller time constants. Sprinkler thermal elements with low time constants have low ratios of mass

to surface area. This is the basis of quick-response sprinklers.
10-8

The RTI is defined by the following equation:

 (10-1)

Where:

me = mass of element (kg)

p(e) c = specific heat of element (kJ/kg-K)

he = convective heat transfer coefficient (kW/m -K) 2

Ae = surface area of element (m )

2

ujet = velocity of gas moving past the sprinkler (m/sec)

Table 10-3 provides generic RTIs for sprinklers.

Table 10-3. Generic Sprinkler Response Time Index (RTI)

Common Sprinkler Type Generic Response Time Index

RTI

(m-sec)1⁄2

Standard response bulb 235

Standard response link 130

Quick response bulb 42

Quick response link 34

NFPA 13 states that “ordinary-temperature-rated sprinklers shall be used throughout the buildings”

unless the temperature of the building is other than normal. NFPA 13 goes onto define three cases

that would follow in the event of an “abnormal” temperature: These cases are as follows:

(1) “When the maximum ceiling temperatures exceed 38 °C (100 °F), sprinklers with temperatures

in accordance with the maximum ceiling temperatures of Table 10-1 shall be used.”

(2) “Intermediate- and high-temperature sprinklers shall be permitted to be used throughout

ordinary and extra hazard occupancies.”

(3) Sprinkler should be installed with intermediate-temperature classification if they are “located

within 12 in. (305 mm) to one side or 30 in. (762 mm) above an uncovered steam main,

heating coil, or radiator; sprinklers under glass or plastic skylights exposed to direct rays of

the sun; sprinklers in an unventilated, concealed space, under an uninsulated roof, or in an

unventilated attic; or sprinklers in unventilated show windows having high-powered electric

lights near the ceiling. Sprinklers within 2.1 m (7 ft) of a low-pressure blow-off valve that

discharges free in a large room” should be classified with high-temperature classification.

Sprinklers protecting commercial-type cooking equipment and ventilation systems shall be

of the high-or extra-high-temperature classification as determined by use of a temperature

measuring device.”
10-9

10.3.4 Sprinkler Activation

As part of a fire hazard analysis, it is often desirable to estimate both the burning characteristics

of selected fuels and their effects in enclosures, as well as when fire protection devices (such as

automatic sprinklers or heat and smoke detectors) will activate for specific fire conditions.

Equations are available to permit the user to estimate these effects, principally on the basis of

experimental correlations.

It has been determined experimentally that convective heat transfer is the most important element

in activating sprinklers. Convective heat transfer involves heat transfer through a circulating

medium, which, in the case of fire sprinklers, is the room air. The air heated by the fire rises in a

plume, entraining other room air as it rises. When the plume hits the ceiling, it generally splits to

produce a ceiling gas jet (ceiling jet refers to the relatively rapid gas flow in a shallow layer beneath

the ceiling surface, which is driven by the buoyancy of the hot combustion products). The thickness

of the ceiling jet flow is approximately 5 to 12-percent of the height of the ceiling above the fire

source, with the maximum temperature and velocity occurring 1-percent of the distance from the

ceiling to the fire source. The heat sensing elements of the sprinklers within this ceiling jet are then

heated by conduction of the heat from the air.

Researchers have developed computer programs to calculate the response time of sprinklers

installed below the unconfined ceilings. These programs can determine the time to operation for

a user specified fire HRR history. They are convenient to use because they enable the analyst to

avoid the tedious repetitive calculations needed to analyze a growing fire. However, an analyst can

easily perform these calculations with a scientific hand calculator for steady fires that have a

constant HRR. In cases requiring a more detailed analysis of a fire that has important changes in

HRR over time, the fire may be represented as a series of steady fires occurring immediately after

one another.

For activation steady-state fires, the time (t ) required to heat the sensing element of a suppression

device from room temperature to operation temperature is given by the following equation (Budnick,

Evans, and Nelson, 1997):

 (10-2)

Where:

activation t = sprinkler head activation time (sec)

RTI = response time index (m-sec)1⁄2

ujet = ceiling jet velocity (m/sec)

Tjet = ceiling jet temperature (°C)

Ta = ambient air temperature (°C)

Tactivation= activation temperature of sprinkler head (°C)
10-10

The expressions for estimating the maximum ceiling jet temperature and velocity as a function of

ceiling height, radial position, and HRR were developed from analysis of experiments with largescale fires having HRR from 668 kW to 98,000 kW. The expressions are given for two regions—

one where the plume directly strikes the ceiling and the other outside the plume region where a true

horizontal flow exists.

The ceiling jet temperature and velocity correlations of a fire plume are given by the following

expressions:

 (10-3)

 (10-4)

 (10-5)

 (10-6)

Where:

Tjet = ceiling jet temperature (°C)

Ta = ambient air temperature (°C)

= heat release rate of the fire (kW)

r = radial distance from the plume centerline to the sprinkler head (m)

H = distance from the top of the fuel package to the ceiling level (m)

ujet = ceiling jet velocity (m/sec)

The above correlations are used extensively to calculate the maximum temperature and velocity

in the ceiling jet at any distance, r, from the fire axis. Note that the regions for which each

expression is valid are given as a function of the ratio of the radial position, r, to the ceiling height,

H. Moving away from the centerline of the plume jet, r/H increases. For regions where r/H>0.18,

Equation 10-4 is used. Based on the cases where the hot gases have begun to spread under a

ceiling located above the fire, Equation 10-3 applies for a small radial distance, r, from the

impingement point. (See Figure 10-3.)
10-11

Figure 10-3 Ceiling Jet Flow Beneath an Unconfined Ceiling and Sprinkler Activation

As w jet ith the velocities in the ceiling jet flow, u , there are two regions, under a ceiling including

(1) one close to the impingement point where velocities are nearly constant and (2) another farther

away where velocities vary with radial position.

The ceiling jet temperature is important in fire safety because it is generally the region where

sprinklers are located; therefore, knowledge of the temperature and velocity of the ceiling jet as a

function of position enables us to estimate the sprinklers response time.

The temperature and velocity of a ceiling jet also vary with the depth of the jet. Moving away from

the ceiling, the temperature increases to a maximum, then decreases closer to the edge of the jet.

This profile is not symmetric as it is with a plume, the maximum occurs along the plume centerline.

With knowledge of plume ceiling jet temperature and velocity, we can estimate the actuation time

of a sprinkler, if we also know the spacing and the speed or thermal inertia of the sprinkler.

The response of a sprinkler head is given by its RTI.

10.3.5 Sprinkler Spray Interaction with Plume

Once a sprinkler head actuates, water must penetrate the plume to reach the burning fuel surfaces.

For this reason, the droplets must have sufficient velocity and size to penetrate through the hot

gases flowing in the opposite direction. If a droplet is too small, it will evaporate and/or be moved

upward by the plume. For very high-energy release rate fires that grow quickly, it is sometimes

necessary to use large drop sprinklers designed to yield droplet sizes and velocities that carry the

drops through the plume and flame onto the burning surface.
A flat shield installed above sprinklers. 1

NRC Information Notice 2002-24, “Potential Problems with Heat Collectors on Fire Protection 2

Sprinklers,” July 19, 2002.

10-12

10.4 Assumptions and Limitations

The methods discussed in this chapter are subject to several assumptions and limitations:

(1) The method assumes the ceiling is unconfined, unobstructed, smooth, flat, and horizontal.

The method does not account for effects due to walls or overhead obstructions.

(2) The plume ceiling jet correlations of temperature and velocity assume that the fire source

is located away from walls and corners. The primary impact of walls and corners is to

reduce the amount of entrained air into the plume. This has the effect of lengthening flames

and causing the temperature in a plume to be higher at a given elevation than it would be

in the open.

(3) The correlations for estimating the maximum ceiling jet temperature and velocity were

developed for steady-state fires and plumes under unconfined ceilings (where the smoke

layer does not develop below the ceiling jet during the time of interest).

(4) The plume ceiling jet correlations are valid for unconfined ceilings, as the environment for

the outside ceiling jet is uniform in temperature and atmospheric ambient.

(5) All calculations for determining time to operation only consider the convective heating of

sensing elements by the hot fire gases. They do not explicitly account for any direct heating

by radiation from the flames. The sprinkler is treated as a lumped mass model. The

lumped model assumes that thermal gradients are neglected within the thermal element.

(6) This method does not apply to predict response time of sprinklers installed on heat

collectors far below the ceiling (in mid air). When sprinklers are too far below the ceiling, 1

most of the heat energy rises past the sprinklers and heat collectors and the sprinklers are

not activated. Locating the sprinkler close to the ceiling ensures that the sprinkler will be

in the hot gas layer, minimizing activation time and enabling the sprinkler to provide a fully

developed water supply pattern to control the fire .

2

10.5 Required Input for Spreadsheet Calculations

The user must obtain the following parameters before using the spreadsheet:

(1) heat release rate of the fire (kW)

(2) activation temperature of the sprinkler (°F)

(3) distance from top of fuel package to the ceiling (ft)

(4) radial distance from the plume centerline to the sprinkler (ft)

(5) ambient air temperature (°F)

(6) sprinkler type
10-13

10.6 Cautions

(1) Use (10_Detector_Activation_Time.xls) and select the “Sprinkler” spreadsheet

on the CD-ROM for estimating sprinkler response time.

(2) Make sure to input parameters using the correct units.

10.7 Summary

This chapter discusses a method of calculating the response time of sprinkler under an unconfined

smooth ceiling in response to steady-state fires. Parameters H and r both relate to the calculation

of sprinkler actuation time.

10.8 References

Bryan, J.L., Automatic Sprinkler and Standpipe Systems, 2 Edition, Appendix C, “Operating nd

Temperature (Bath) Test,” p. 505, National Fire Protection Association, Quincy, Massachusetts,

1990.

Budnick, E.K., D.D. Evans, and H.E. Nelson, “Simplified Fire Growth Calculations” Section 11,

Chapter 10, NFPA Fire Protection Handbook, 18 Edition, A.E. Cote, Editor-in-Chief, National Fire th

Protection Association, Quincy, Massachusetts, 1997.

Isman, K.E., “Automatic Sprinklers” Section 6, Chapter 9, NFPA Fire Protection Handbook, 18 Edition, th

A.E. Cote, Editor-in-Chief, National Fire Protection Association, Quincy, Massachusetts, 1997.

NFPA 13, “Standard for Installation of Sprinkler Systems,” 2002 Edition, National Fire Protection

Association, Quincy, Massachusetts.
10-14

10. 9 Additional Readings

Alpert, R.L., “Calculation of Response Time of Ceiling-mounted Fire Detectors,” Fire Technology,

Volume 8, pp. 181–195, 1972.

Alpert, R.L., and E.J. Ward, “Evaluation of Unsprinklered Fire Hazard,” Fire Safety Journal, Volume 7,

No. 177, 1984.

Bryan, J.L., Fire Suppression and Detection Systems, Macmillan Publishing Company, New York,

1993.

Fire Dynamics Course Guide, Federal Emergency Management Agency (FEMA), United States

Fire Administration (USFA), National Emergency Training Center, Emmitsburg, Maryland, 1995.

Heskestad, G., “Fire Plumes,” Section 2, Chapter 2, SFPE Handbook of Fire Protection Engineering,

2 Edition, P.J. DiNenno, Editor-in-Chief, National Fire Protection Association, Quincy, nd

Massachusetts, 1995.

Schifiliti, R.P., B.J. Meacham, and R.P. Custer, “Design of Detection Systems,” Section 4, Chapter 1,

SFPE Handbook of Fire Protection Engineering, 2 Edition, P.J. DiNenno, Editor-in-Chief, National nd

Fire Protection Association, Quincy, Massachusetts, 1995.

Zalosh, R.G., Industrial Fire Protection, John Wiley & Sons Ltd., West Sussex, England, 2003.
10-15

10.10 Problems

Example Problem 10.10-1

Problem Statement

A fire with = 1,000 kW occurs in a space that is protected with sprinklers. Sprinklers are rated

at 165 °F (74 °C) [standard response link with RTI = 130 (m-sec) ] and located 9.8 ft (3 m) 1⁄2

on center. The ceiling is 9.8 ft (3.0 m) above the fire. The ambient temperature is 77 °F. Would

the sprinklers activate, and if so how long would it take for them to activate?

Solution

Purpose:

(1) Determine if the sprinklers will be activated for the fire scenario.

(2) If the sprinkles are activated, how long would it take for them to activate?

Assumptions:

(1) The fire is located away from walls and corners.

(2) The fire is steady state.

(3) The ceiling is unconfined.

(4) Only convective heat transfer from the hot fire gases is considered.

(5) There is no heavily obstructed overhead.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 10_Detector_Activation_Time.xls (click on Sprinkler)
10-16

FDT Input Parameters: s

-Heat Release Rate of the Fire = 1,000 kW

-Distance from the Top of the Fuel Package to the Ceiling (H) = 9.8 ft

-Radial Distance from the Plume Centerline to the Sprinkler (r) = 9.8 ft

a

-Ambient Air Temperature (T ) = 77 °F

-Select Type of Sprinkler = Standard response link

-Select Sprinkler Classification = Ordinary

Note: Ordinary classification has been selected because the rated value for the sprinklers

in this problem (165 °F) is within the range of temperature ratings for ordinary sprinklers

(135 °F – 170 °F).

Results*

Sprinkler Type Spr activation inkler Activation Time (t )

(min.)

Standard

response link

2.9

*see spreadsheet on next page
10-17

Spreadsheet Calculations

FDT : 10_Detector_Activation_Time.xls (Sprinkler) s

CHAPTER 10o ESTIMATING SPRINKLER RESPONSE TIME 

Ve<Sion 180So0 

The following calculations estima!Jl sprinkler acti\G1ion time. 

Parameters in YELLOW CELLS are Ertered by the User. 

Parameters in GREEN CELLS are Automatically Selectedfromthe ORO P DOWN M ENUforthe Spriri<ler Selected. 

All subsequent oUiput \Glues are calcolat»ld bythe spreadsheet and based on wlues speci1ied in the input 

parameters. This spreadsheet is protect»ld and secure to avoid errors due to a wrong entry in a cell(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

Heat Release Rate ofthe Fire (Q)(St»lady Stne) 

Sprinkler Response Time Index (RTI) 

kthmion T emper.Jture of the Sprinkler (T.,.,..,.,,..) 

Height of Ceiling above Top of Fuel (H) 

Radial Distance to the Detector (r) ""'nevermore than 0.707 or 1/2\Q oflhe li~d spacinQu 

.Anbient ~r Tempel'3ture (T,.) 

Convective Heat ~lease Rate Fraction (1,) 

r.+l = 1.00 

GEN ER 1C SPR 1NKL ER RESPONSE T 1ME 1NDEX (RT1r 

Common Sprinkler Twe Generic Response 

Time hdex(RTO(m-sec)""' 

Select Type of Sprinkle- I standard rt •ll:onu lin" 

1000.00 t 

130 ( 

w 

IJ\" ) '<J 

165 ° 

9.8011 

9.8011 

68.00 ° 

0.70 

I Calt ulate II 

IH 

Standard response bulb 235 Scroll to desired sp-iri<lert ype then Click on sel ecti en 

Standard response link 130 

Quick response bulb 42 

Quick response link 34 

User Soeci,ed \l.ilue Enter \l.ilue . 00 

~~ "t rr.~. r.~;ylv:f ":N, O, t<?;~o:t,..v.« $ p!:r.AIN .:.rtlt.O r. .;t,..v.M hxi; - AS /.FU..,ft$. IT tr.:f:cr.a• C~H¥: or. )"("$ H¥: :m:!Er.V. ~~ 1 • Pt«c«lr(l; 

X.l:f<'«"\ o.:Jh:y. M>1=h.t:<'ft:. 1tt;:_ P;:<;; 07. 

* Ncte: The actLB I temperature rating shoU d be used when the value is avail able. 

1 3.89 ·c 

zooo ·c 

<:9)00 K 
10-18

ESTIMATING SPRINKLER RESPONSE TIME 

l'l: 'I! rw:.:: Nl"PA ,:it? ro;tK.:t -..~ .'·fil'.'ldOO t 7 \lr.o. 5:!/t\lfi. CJ. Pil'g? 3-'14>. 

b:t cn = (RTI(v'-'~~)(ln (T•~•· T ~T ~tl· T4>:1t:.)l:t\)) 

Where b :t;.)l:n= sprinkler activation response time (sec) 

RTI = spriri< ler response time index (m-sec) 1

'

2 

u~• =ceiling jet velocity (m/sec) 

Tid= ceiling jettemperature ( 0C) 

~ = ambient air temper ab.Jre (°C) 

~: t:.)l n = activation temperature of sprinkler (°C) 

Ceiling Jet Temperature Calculation 

T1d· To)= 16.9 (Oe)..:>s/H :.>J 

Z') T1d· T .)= 5.33 (Oclr) .+1 

Where T•~• =ceiling jettemperature ( 0C) 

T.) = ambient air temper ab.ue (°C) 

for r/H = 0.18 

for r/H > 0.18 

Oe = convective portion of the heat release rate (kW) 

H =height of ceiling above top offuel(m) 

r = radial distance from the plume centerline to the sprinkler (m) 

Con>.Ective Heat Release Rete Calculction 

Oe=1c 0 

Where Oe = convective portion of the heat release rate (kW) 

Q = heat releaser ate of the fire (kW) 

Oe= 

1e =convective heat release rate fraction 

700kW 

Radial Dislanceto Ceiling Height Rctio Calculation 

r/H = 1.00 uH >0.15 

Tr~•· T ~= {5.38 (Qc/r)'\2.<3}.+1 

Trd· T ~= 68.46 

Trd= 88.46 (•c) 

Ceiling Jet Velocity Calculation 

'-'~•= 0.93 (Q/H) 113 

'-'~•= (0.195 0 113 11')tr ~ 

Where U~tl =ceiling jet velocity (m/sec) 

Q = heat releaser ate of the fire (kW) 

H =height of ceiling above top offuel(m) 

for r/H = 0.15 

for r/H > 0.15 

r = radial distance from the plume centerline to the sprinkler (m) 

Radial Distanceto Ceiling Height Rctio Calculation 

r/H = 1.00 r.+l > 0.15 

'-'~•= (0.195 0111/3 Hll112)/1"'516 

1.354 m/sec 
10-19

Sprinlder Actiwtion Time Calculction 

1«t cn = (RTI.(v'-'~~)(ln (T•~•· T ~T ~•· ~: ~• .\)) 

tMt<Ahn = 172.85 sec 

!!The sprinlder Wll respond in approxi mctey 2.88 minutes 

NOTE: If t,., " ' •"- "'NUM'' Sl>rinkler does not activate 

[Mti.t,M 

The above calculations are based on principles developed in the NFPA Fire Protection Hand book 

19hEdition, 2003. Calculations are based on certain assumptions and have inherent limitations. 

The results of such calculations may or may not have reasonable predictive capabilities for a given 

situation, and should only be interpreted by an informed user. 

Anhough each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolute guarantee of the accuracy of these calculations. 

Arfl/ questions. comments, concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or mxs3@nrc.gov. 
10-20

Example Problem 10.10-2

Problem Statement

If the sprinklers in Problem 10-1 are replaced by sprinklers with a response time index (RTI)

of 235 (m-sec) , how long would it take for them to activate? 1⁄2

Solution

Purpose:

(1) Determine the activation time for the specified sprinkles under the fire scenario

of Problem 10-1.

Assumptions:

(1) The fire is located away from walls and corners.

(2) The fire is steady state.

(3) The ceiling is unconfined.

(4) Only convective heat transfer from the hot fire gases is considered.

(5) There is no heavily obstructed overhead.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 10_Detector_Activation_Time.xls (click on Sprinkler)

FDT Input Parameters: s

-Heat Release Rate of the Fire = 1000 kW

-Distance from the Top of the Fuel Package to the Ceiling (H) = 9.8 ft

-Radial Distance from the Plume Centerline to the Sprinkler (r) = 9.8 ft

a

-Ambient Air Temperature (T ) = 77 °F

-Select Type of Sprinkler = Standard response bulb

-Select Sprinkler Classification = Ordinary

Note: The RTI value of 235 (m-sec) corresponds to standard response bulb 1⁄2 

sprinkler. Ordinary classification has been selected because the rated value for the

sprinklers in this problem (165 °F, same as Problem 10-1) is within the range of

temperature ratings for ordinary sprinklers (135 °F – 170 °F).

Results*

Sprinkler Type Spr activation inkler Activation Time (t )

(min.)

Standard

response bulb

5.2

 *see spreadsheet on next page
10-21

Spreadsheet Calculations

FDT : 10_Detector_Activation_Time.xls (Sprinkler) s

CHAPTER 10o ESTIMATING SPRINKLER RESPONSE TIME 

Ve<Sion 180So0 

The following calculations estima!Jl sprinkler acti\G1ion time. 

Parameters in YELLOW CELLS are Ertered by the User. 

Parameters in GREEN CELLS are Automatically Selectedfromthe ORO P DOWN M ENUforthe Spriri<ler Selected. 

All subsequent oUiput \Glues are calcolat»ld bythe spreadsheet and based on wlues speci1ied in the input 

parameters. This spreadsheet is protect»ld and secure to avoid errors due to a wrong entry in a cell(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

Heat Release Rate ofthe Fire (Q)(St»lady Stne) 

Sprinkler Response Time Index (RTI) 

kthmion T emper.Jture of the Sprinkler (T.,.,..,.,,..) 

Height of Ceiling above Top of Fuel (H) 

Radial Distance to the Detector (r) ""'nevermore than 0.707 or 1/2\Q oflhe li~d spacinQu 

.Anbient ~r Tempel'3ture (T,.) 

Convective Heat ~lease Rate Fraction (1,) 

r.+l = 1.00 

GEN ER 1C SPR 1NKL ER RESPONSE T 1ME 1NDEX (RT1r 

Common Sprinkler Twe Generic Response 

Time hdex(RTO(m-sec)""' 

Select Type of Sprinkle- I standard rt •ll:onu biJb 

1000.00 t 

235 ( 

w 

IJ\" ) '<J 

165 ° 

9.8011 

9.8011 

68.00 ° 

0.70 

I Calt ulate II 

IH 

Standard response bulb 235 Scroll to desired sp-iri<lert ype then Click on sel ecti en 

Standard response link 130 

Quick response bulb 42 

Quick response link 34 

User Soeci,ed \l.ilue Enter \l.ilue . 00 

~~ "t rr.~. r.~;ylv:f ":N, O, t<?; o:t,..v.« $ p!:r.AIN .:.rtlt.O r. .;t,..v.M hxi; - AS /.FU..,ft$. IT tr.:f:cr.a• C~H¥: or. )"("$ H¥: :m:!Er.V. ~~ 1 • Pt«c«lr(l; 

X.l:f<'«"\ o.:Jh:y. M>1=h.t:<'ft:. 1tt;:_ P;:<;; 07. 

* Ncte: The actLB I temperature rating shoU d be used when the value is avail able. 

1 3.89 ·c 

zooo ·c 

<:9)00 K 
10-22

ESTIMATING SPRINKLER RESPONSE TIME 

l'l: 'I! rw:.:: Nl"PA ,:it? Pro;tK.:t~-..~ .'·fil'.'l OO~t 7 \lr.o. 5:!/t\lfi. ~CJ. Pil'g? 3-'14>. 

b:t cn = (RTI(v'-'~~)(ln (T•~•· T ~T ~tl· T4>:1t:.)l:t\)) 

Where b :t;.)l:n= sprinkler activation response time (sec) 

RTI = spriri< ler response time index (m-sec) 1

'

2 

u~• =ceiling jet velocity (m/sec) 

T1d =ceiling jettemperature ( 0C) 

~ = ambient air temper ab.Jre (°C) 

~: t:.)l n = activation temperature of sprinkler (°C) 

CeilinA Jet Temperature Calculation 

T1d· To)= 16.9 (Oe)z>3

/H93 

Z') T1d· T .)= 5.33 (Oclr) .+1 

Where ~• =ceiling jettemperature ( 0

C) 

T.) = ambient air temperature (°C) 

for r/H = 0.18 

for r/H > 0.18 

Oe = convective portion of the heat release rate (kW) 

H =height of ceiling above top offuel(m) 

r = radial distance from the plume centerline to the sprinkler (m) 

Con-.ective Heat Release Rete Caculction 

Oe=1cQ 

Where Oe = convective portion of the heat release rate (kW) 

Q = heat releaser ate of the fire (kW) 

Oe= 

1e =convective heat rele.as e rate fraction 

700kW 

Radia Distanceto Ceiling Height Rctio Calculation 

r/H = 1.00 uH >0.15 

Tr~•· T ~= {5.38 (Qc/r)'\2.<3}.+1 

Trd· T ~= 68.46 

Trd= 88.46 (•c) 

Ceiling Jet Velocity Calculation 

u~•= 0.93 (Q/H) ., .. 

'-'~•= (0.195 a•a 11')rr ~ 

Where u~r =ceiling jet velocity (m/sec) 

Q = heat releaser ate of the fire (kW) 

H =height of ceiling above top offuel(m) 

for r/H = 0.15 

for r/H > 0.15 

r = radial distance from the plume centerline to the sprinkler (m) 

Radia Dislanceto CeilinA Heit=~ht Rctio Calculation 

r/H = 1.00 r.+l > 0.15 

u~•= (0.195 0111/3 Hll112)/r"5/6 

1.354 m/sec 
10-23

Sprinlder Actiwtion Time Calculction 

~~ en = (RTI(v'-'~~)(ln (T1~1· T ~T ~tl· T4>:1t:.)l:t\)) 

The above calculations are based on principles developed in the NFPA Fire Protection Hand book 

19hEdition, 2003. Calculations are based on certain assumptions and have inherent limitations. 

The results of such calculations may or may not have reasonable predictive capabilities for a given 

situation, and should only be interpreted by an informed user. 

Anhough each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolute guarantee of the accuracy of these calculations. 

Arfl/ questions, comments, concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or mxs3@nrc.gov. 

11-1

CHAPTER 11. ESTIMATING SMOKE DETECTOR RESPONSE TIME

11.1 Objectives

This chapter has the following objectives:

• Introduce the critical factors that influence smoke detector performance.

• Identify the various types of smoke detectors.

• Describe how to estimate the response time of a smoke detector.

11.2 Introduction

Reliable fire detection is an essential part of the fire protection program in nuclear power plants

(NPPs), it relates to both fire control or extinguishment and safe evacuation of occupants. Most of

the devices associated with fire detection and suppression are typically located near the ceiling

surfaces. In the event of a fire, hot gases in the fire plume rise directly above the burning fuel and

impinge upon the ceiling. The ceiling surface causes the flow to turn and move horizontally

beneath the ceiling to other areas of the building located at some distance from the fire. The

response of detection devices (heat/smoke detectors) and sprinklers installed below the ceiling

submerged in this hot flow of combustion products provides the basis for the building’s active fire

protection features.

Smoke and heat detectors are best suited for fire detection in confined spaces, where rapid heat

generation can be expected in the event of a fire. Smoke and heat detectors have been installed

extensively in most NPPs. Generally, such detectors are installed as part of a building-wide alarm

system, which typically alarms in the main control room (MCR). The purpose of such systems is

to provide early warning to building occupants, and rapid notification of the fire brigade. Some

detection devices will also perform the function of automatically actuating suppression systems and

interfacing with other building systems such as heating, ventilation, and air-conditioning (HVAC).

Detection is critical to fire safety in NPPs since a potential fire hazard may jeopardize safe plant

shutdown. Consequently, safety-related systems must be protected before redundant safetyrelated systems become damaged by a fire.

Throughout the nuclear industry there has been considerable responsive action relative to the

nuclear safety-related fire protection and incorporating sound fire protection principles in nuclear

facility design. New standards, regulatory guides, and criteria have been publicized since the fire

at the 1975 Browns Ferry Nuclear Power Plant (BFNP). Recognizing the unique characteristics of

fires in NPPs, requirements have been established for locating smoke detectors. Particular

emphasis has been given to establishing criteria for early warning detection of electrical cable fires.

Figure 11-1 shows a qualitative relationship between time and damage for different rates of fire

development and average detection reaction and fire fighting.
11-2

11.3 Characteristics of Smoke Production

Two essential factors influencing the performance of smoke detectors are the particle size of the

smoke and the fire-induced air velocities. The velocities created by the thermal column tend to

diffuse the smoke through the upper wall and ceiling regions of the enclosure where the particles

enter the detector and activate the unit. For example, residential detectors respond effectively to

air flow velocities above 0.25 m/sec (50 ft/min) generated by flaming combustion. The same

detectors may fail to respond when the fire-induced thermal column velocities created by the

smoldering fire are below 0.15 (30 ft/min).

Figure 11-1 Qualitative Relationship Between Time and Damage

for Different Speeds of Fire Development and Average Detection, Reaction, and Fire Fighting

(NUREG/CR-2409, “Requirements for Establishing Detector Siting Criteria in Fires Involving Electrical Materials”)
11-3

Smoke production of a given fuel material varies with the sample size, arrangement, and

configuration of the fuel; material moisture content; and ignition energy. Custer and Bright (1974)

report that the earliest indication of a fire occurrence usually involves the heating of materials during

the pre-ignition stage, which produces submicron particles ranging in size from 5x10 –1x10 -4 -3

micrometer. Custer and Bright also reported that the size of the particle produced by the diffusion

flame combustion varies with the heating of the atmosphere and the development of the fire

progressing from smoldering to flaming combustion. Larger particles are formed by coagulation,

with the particle size distribution varying between 0.1 micrometer and 4.0 micrometers. The smaller

particles, below 0.1 micrometer, tend to disappear as a result of the formation of larger particles by

coagulation, while the larger particles tend to settle out through the process of sedimentation. The

particle size appears to be one of the most critical variables relative to the operation and

performance of the specific smoke detector unit, considering that the detector is suitably located

to be exposed to the smoke concentrations, and it is designed to enhance the entry of smoke into

the detector unit.

Budnick (1984) states that the critical variables affecting the activation of a smoke detector

are as follows:

A smoke detector responds to an accumulation of smoke particulate within the device’s

sensing chamber. In a developing fire, the response will depend on a complex

interrelationship of environmental factors such as fire size and growth rate, fuel type and

smoke generation rate, room geometry and ventilation, and detector characteristics such as

location, smoke entry characteristics and predetermined detector sensitivity thresholds.

Relative to the rate of fire development, diffusion flame combustion appears to vary with the velocity

of the flame spread (which is influenced by fuel arrangement and configuration), ventilation velocity,

oxygen concentrations, and energy input at ignition.

11.4 Operating Principles of Smoke Detectors

Typically, a smoke detector will detect most fires more rapidly than a heat detector. Visible

products of combustion consist primarily of unconsumed carbon and carbon-rich particles, while

invisible products of combustion consist of solid particles smaller than 5 microns, as well as various

gases and ions. NFPA 72, “National Fire Alarm Code ,” defines the types of listed smoke detectors ®

in the following manner:

• Photoelectric light obscuration smoke detection is the principle of using a light source

and a photosensitive sensor onto which the principal portion of the source emission is

focused. When smoke particles enter the light path, some of the light is scattered and some

is absorbed, thereby reducing the light reaching the receiving sensor. The light reduction

signal is processed and used to convey an alarm condition when it meets preset criteria

(see Figure 11-2).

• Photoelectric light scattering smoke detection is the principle of using a light source and

a photosensitive sensor arranged so that the rays from the light source do not normally fall

onto the photosensitive sensor. When smoke particles enter the light path, some of the light

is scattered bu reflection and refraction onto the sensor. The light signal is processed and

used to convey an alarm condition when it meets preset criteria (see Figure 11-2).
11-4

Figure 11-2 Illustration of the Photoelectric Principle

• Ionization smoke detection is the principle of using a small amount of radioactive material

to ionize the air between two differentially charged electrodes to sense the presence of

smoke particles. Smoke particles entering the ionization volume decrease the conductance

of the air by reducing ion mobility. The reduced conductance signal is processed and used

to convey an alarm condition when it meets preset criteria (see Figure 11-3).

Figure 11-3 Illustration of the Ionization Principle

• Combination detection either responds to more than one of the fire phenomena or

employs more than one operating principle to sense these phenomena. Typical examples

are a combination of heat and smoke detectors or a combination of rate-of-rise and

fixed-temperature heat detectors.
11-5

• Projected beam detection uses the principle of photoelectric light obscuration smoke

detection, but the beam spans the protected area.

• Air sampling detection uses a piping or tubing distribution network that runs from the

detector to the area(s) to be protected. An aspiration fan in the detector housing draws air

from the protected area back to the detector through air sampling ports, piping, or tubing.

At the detector, the air is analyzed for fire products.

As a class, smoke detectors using the ionization principle provide a somewhat faster response to

high-energy (open flaming) fires, since such fires produce large numbers of the smaller smoke

particles. Smoke detectors operating on the photoelectric principle tend to respond faster to the

smoke generated by low-energy (smoldering) fires, which generally produce more of the larger

smoke particles. However, each type of smoke detector is subjected to, and must pass, the same

fires at testing laboratories in order to be listed by Underwriters Laboratories (UL).

Combustion product detectors of the ionization type are called spot detectors (meaning that the

element is concentrated at a particular location), and those of the photoelectric type are available

as both spot detectors and line detectors. A line detector means that detection is continuous along

a path. Ionization detectors are usually found as spot detectors for area protection, and may be

modified with air shields or sampling tubes for installation as air duct detectors. Projected beam

photoelectric detectors are most often applied as line detectors for large open area protection. Line

detectors are also beneficial in areas with high ceilings. They give the earliest warnings of

abnormal conditions in these applications by responding to the smoke particles produced by fires.

By contrast spot detectors are typically located in various areas of the building. They typically

protect areas up to 84 m (900 ft ) depending on ceiling surface conditions and room height. 2 2

Ionization and photoelectric detectors offer the greatest potential in residential safety. Some

ionization and photoelectric detectors are also manufactured with dual modes of operation.

Specifically, a fixed-temperature, thermal-activation device is also located in the detector.

Most conventional smoke detectors provide a binary go/no-go form of detection. This means that

other than alarm or no-alarm condition, no other information is transmitted to the fire alarm control

unit. In order to provide a stable smoke detector, the system design must ensure that the sensitivity

level of the detector matches the environment in the facility to be protected. Newer types of spot

smoke detectors are now capable of providing information on the level of smoke at the device.

Current standards (such as NFPA 72, National Fire Alarm Code ) stipulate the spacing of smoke ®

detectors based upon tests performed by nationally recognized testing laboratories such as

Underwriters Laboratories (UL 268). An alternative performance design method can be found in

Appendix B to NFPA 72 and is limited to flaming fires no ceilings higher than 8.5 m (30 ft). This

method was developed from an experimental study conducted in the late 1970s for the Fire

Detection Institute (FDI), however, it suffers from certain limitations related to the scope of the

experiments conducted. Nevertheless, this design method introduced some important concepts,

including design of a detection system to activate for a critical fire size (HRR) representing an

acceptable threat level for the protected space. This is a departure from the earlier concept of

detection “as quickly as possible,” which often led to oversensitivity.
11-6

Technology improvements in microprocessor use in fire alarm systems have led to development

of new smoke detector concepts. These new sensors use analog technology to measure the

conditions in the protected area, or space, and transmit that information to the computer-based fire

alarm control unit. Thus, the new sensors can report when components are too dirty to function

properly or too sensitive as result of any number of conditions in the protected space. Analog

sensors provide an essentially false-alarm-free system with regard to the conditions that are

normally found in a building. This sensor technology also allows the system designer to adjust the

sensor’s sensitivity to accommodate the ambient environment or use an extra-sensitive setting to

protect a high-value or mission-sensitive area. These sensors are available as photoelectric;

ionization; or combination thermal, photoelectric, and ionization units. As fire alarm system

technology continues to advance and existing NPPs are upgraded, the analog sensors will be the

sensors of choice for any system application, regardless of system size.

11.5 Smoke Detector Response

The response characteristics of smoke detectors are not as well understood as those of sprinklers

and thermal detectors. Smoke detector alarm conditions depend on more than smoke

concentration. Smoke particle sizes and optical or particle scattering properties can affect the

smoke concentration value necessary to reach the alarm condition. For sprinklers and thermal

detectors, measured values of response time index (RTI) characterize the lag time between gas

temperature and sensing element temperature. For smoke detectors, there is no analogous

method to characterize the lag time between gas flow smoke concentration and the smoke

concentration within the sensing chamber. In the absence of understanding the many processes

affecting smoke detector response, smoke detectors can be approximated as low-temperature heat

detectors with no thermal lag (i.e., low-RTI devices).

The time required for automatic actuation of a smoke detector is dependent on fire size, geometry,

type of detector, and environment conditions within the compartment. In many installations, ceilingmounted spot smoke detectors have been suggested as one means of fire detection. In some

cases, the actuation time for ceiling-mounted spot smoke detectors may be unacceptably long.

Projected beam smoke detectors may be the preferable means of fire detection. The actuation time

of ceiling-mounted smoke detectors can be estimated by considering the temperature of the smoke

layer (Heskestad and Delichatsios, 1977).
11-7

11.5.1 Method of Alpert

Smoke detector activation is identical to that for a heat detector, with the exception of the response

of smoke detectors to a modest rise in the ceiling jet temperature. Heskestad and Delichatsios

(1977) correlated a smoke temperature change of 10 °C (18 °F) from typical fuels.

For steady-state fire, the method for estimating the response of a smoke detector is based on the

correlations developed by Alpert (1972) for activation of a sprinkler and is given by the following

equation (Budnick, Evans, and Nelson, 1997):

 (11-1)

Where:

activation t = sprinkler head activation time (sec)

RTI = Response Time Index (m-sec)1⁄2

ujet = ceiling jet velocity (m/sec)

Tjet = ceiling jet temperature (°C)

Ta = ambient air temperature (°C)

Tactivation= activation temperature of detector (°C)

Factory Mutual Research Corporation (FMRC) developed the RTI concept to be a fundamental

measure of thermal detector sensitivity. A detector’s RTI is determined in plunge tests with a

uniform gas flow of constant temperature and velocity and can be used to predict the detector’s

activation time in any fire environment. For the purpose of calculating smoke detector response

time, it is assumed that the smoke detectors are low-RTI devices.
11-8

The ceiling jet temperature and velocity correlations of a fire plume in Equation 11-1 are given

by the following expression:

 (11-2)

 (11-3)

 (11-4)

 (11-5)

Where:

Tjet = ceiling jet temperature (°C)

Ta = ambient air temperature (°C)

= heat release rate of the fire (kW)

H = distance from the top of the fuel package to the ceiling level (m)

r = radial distance from the plume centerline to the detector (m)

ujet = ceiling jet velocity (m/sec)
11-9

11.5.2 Method of Mowrer

Mowrer (1990) developed a smoke detector response time correlation based on the concept of

smoke transport lag time for quasi-steady fires. The response time of a smoke detector comprises

two separate times, including the transport lag time of the plume and the transport lag time of the

ceiling jet, as illustrated by the following equation:

 (11-6)

Where:

activation t = detector activation time (sec)

pl t = transport lag time of plume (sec)

cj t = transport lag time of ceiling jet (sec)

The pl transport lag time of the plume, t , is the time for the fire gases to reach the ceiling at the plume

centerline and can be represented by the following correlation:

 (11-7)

Where:

pl t = transport lag time of plume (sec)

Cpl = plume lag time constant = 0.67 (experimentally determined)

H = height of ceiling above top of fuel (m)

= heat release rate of the fire (kW)

The t cj ransport lag time of the ceiling jet, t , is the time for the fire gases to reach the detector at the

plume centerline and can be represented by the following correlation:

 (11-8)

Where:

cj t = transport lag time of plume (sec)

r = radial distance to the detector (m)

Ccj = ceiling jet lag time constant = 1.2 (experimentally determined)

H = height of ceiling above top of fuel (m)

= heat release rate of the fire (kW)
11-10

11.5.3 Method of Milke

Milke (1990) presented a method for estimating smoke detector response time based on the

enclosure fire testing described in NUREG/CR-4681. The operation of detectors for smoke from

typical fuels has been correlated to a temperature change from the following correlation:

 (11-9)

Where:

activation t = detector activation time (sec)

H = height of ceiling above top of fuel (m)

= heat release rate of the fire (kW)

 (11-10)

 (11-11)

Where:

H = height of ceiling above top of fuel (m)

= heat release rate of the fire (kW)

Tc = temperature rise of gases under the ceiling for smoke detector to activate

Before estimating smoke detector response time, stratification effects can be calculated.

The potential for stratification relates to the difference in temperature between the smoke and

surrounding air at any elevation and is given by the following correlation (NFPA 92B, Section A.3.4).

 (11-12)

Where:

Hmax = the maximum ceiling clearance to which a plume can rise (ft)

= convective heat release rate of the fire (Btu/sec)

Tf->c = difference in ambient gas temperature between the fuel location and ceiling level (°F)
11-11

The convective portion of the heat release rate, , can be estimated as 70 percent of the total

heat release rate. Thus, is given by the following equation:

Where:

c

 = convective heat release fraction (0.70)

= heat release rate of the fire (Btu/sec)

Difference in ambient gas temperature between the fuel location and ceiling level can be estimated

from the following equation:

Where:

Tf->c = difference in ambient gas temperature between the fuel location and ceiling level (°F)

= convective heat release rate of the fire (Btu/sec)

H = height of ceiling above top of fuel (ft)

max If the H is greater than H, the smoke would be expected to reach the ceiling-mounted smoke

detector and result in activation.

11.6 Assumptions and Limitations

The method discussed in this chapter is subject to several assumptions and limitations.

(1) The fire is steady state.

(2) The forced ventilation system is off. As ventilation is increased, detector response times

increase.

(3) Both flaming and non-flaming fire sources can be used.

(4) Caution should be exercised with this method when the overhead area is highly obstructed.

(5) The detectors are located at or very near to ceiling. Very near to ceiling would include code

compliant detectors mounted on the bottom flange of structural steel beams. This method

is not applicable to detectors mounted well below ceiling in free air.
11-12

11.7 Required Input for Spreadsheet Calculations

The user must obtain the following information before using the spreadsheet.

(1) heat release rate of the fire (kW)

(2) ceiling height of the compartment (ft)

(3) radial distance from the centerline of the plume (ft)

11.8 Cautions

(1) Use (10_Detector_Activation_Time.xls) and select “Smoke” spreadsheet in the CD-ROM

for calculations.

(2) Make sure to use correct units when entering the input parameters.

(3) Remember that there are broad assumptions within each calculation method because of

the statistical makeup of the test methods. Although a specific method may be a good estimate,

use the results with caution.

11.9 Summary

This chapter discusses three methods of calculating the activation time of smoke detectors under

unobstructed ceilings in response to steady-state fires. In the first method, smoke detector

activation is identical to that for a heat detector, with the exception that the response of the smoke

detector to a modest rise in the ceiling jet temperature has been assumed. In the second method,

the response time of a smoke detector was estimated using the transport lag time of the plume and

the transport lag time of the ceiling jet. In the third method, the operation of smoke detectors was

estimated using the stratification of smoke.
11-13

11.10 References

Alpert, R.L., “Calculation of Response Time of Ceiling-Mounted Fire Detectors,” Fire Technology,

Volume 8, pp. 181–195, 1972.

Budnick, E.K., D.D. Evans, and H.E. Nelson, “Simplified Fire Growth Calculations” Section 3,

Chapter 9, NFPA Fire Protection Handbook, 19 Edition, A.E. Cote, Editor-in-Chief, National Fire th

Protection Association, Quincy, Massachusetts, 2003.

Budnick, E.K., “Estimating Effectiveness of State-of-the-Art Detectors and Automatic Sprinklers on

Life Safety in Residential Occupancies,” Fire Technology, Volume 20, No. 3, pp. 5–21, 1984.

Custer, R.L.P., and R.G. Bright, “Fire Detection: The State of the Art,” Technical Note 839, Center

of Fire Research, National Bureau of Standards, Washington, DC, 1974.

Heskestad, G., and M.A. Delichatsios, “Environments of Fire Detectors—Phase 1: Effects of Fire

Size, Ceiling Height and Material,” Volume I, “Measurements” (NBS-GCR-77-86), Volume II,

“Analysis” (NBS-GCR-77-95), National Bureau of Standards, 1977.

Milke, J., “Smoke Management for Covered Malls and Atria,” Fire Technology, Volume 26, No. 3,

pp. 223–243, August 1990.

Morwer, F., “Lag Time Associated With Fire Detection and Suppression,” Fire Technology, Volume 26,

No. 3, pp. 244–265, August 1990.

NFPA 72, National Fire Alarm Code , 1999 Edition, Appendix B: Engineering Guide for Automatic ®

Fire Detection Spacing, National Fire Protection Association, Quincy, Massachusetts.

NFPA 92B, “Guide for Smoke Management Systems in Mall, Atria, and Large Areas,” 2000 Edition,

National Fire Protection Association, Quincy, Massachusetts.

NUREG/CR-2409, “Requirements for Establishing Detector Siting Criteria in Fires Involving

Electrical Materials,” U.S. Nuclear Regulatory Commission, Washington, DC, July 1982.

NUREG/CR-4681, “Enclosure Experiment Characterization Testing for the Base Line Validation

of Computer Fire Simulation Codes,” U.S. Nuclear Regulatory Commission, Washington, DC,

March 1987.

UL 268, “Smoke Detectors for Fire Protective Signaling Systems,” 4 Edition, Underwriters th

Laboratory, Northbrook, Illinois, 1996.

11.11 Additional Readings

Bryan, J.L., Fire Suppression and Detection Systems, Macmillan Publishing Company, New York,

1993.

Schifiliti, R.P., and W.E. Pucci, “Fire Detection Modeling State-of-the-Art,” Fire Detection Institute

(FDI), May 1996.
11-14

Example Problem 11-1: Fire Scenario with Smoke Detector

11.12 Problems

Example Problem 11.12-1

Problem Statement

Estimate the response time of a smoke detector that is located 10 ft radially from the centerline

of a 1,000-kW pool fire in a 13-ft-tall compartment.

Solution

Purpose:

(1) Determine the response time of the smoke detector for the fire scenario.

Assumptions:

(1) The fire is steady state

(2) The forced ventilation system is off

(3) There is no heavily obstructed overhead

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 10_Detector_Activation_Time.xls (click on Smoke_Detector)

FDT Input Parameters: s

-Heat Release Rate of the Fire = 1,000 kW

-Ceiling Height (H) = 13 ft

-Radial Distance from the Plume Centerline to the Smoke Detector (r) = 10 ft

Results*

Heat Release

Rate (kW)

Smoke Detector A Rctivation Time (t ) (sec)

1,000

Method of Alpert Method of Mowrer Method of Milke

0.42 0.74 0.26

*see spreadsheet on next page
11-15

Spreadsheet Calculations

FDT : 10_Detector_Activation_Time.xls (Smoke_Detector) s

CHAPTER 11. ESTIMATIIIG SMOKE DETECTOR RESPOIISE TIME 

Version 18050 

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Ct l1119 Jt tl<t.J Tlllt COUt.'llt(C,.) p•lhH lt.'lll{ O:.IIIIHd) 

nmpH'11U P.la 01Gaa$ UUIH1U Ct l'-9 ) 

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r!H = 0.77 

ESTIMATING SMOKE DETECTOR RESPONSE TIME 

METHOD OF ALPERT 

~ ... "' !§~~,.~~~~, !:;: ~· ""!1' >- "" ===a t .. ,...,_. (P.Ttte ,,.,, (. (r,. -T4l/(r,. -T- .. ..-;» n ~me Qed a sHnH 6mote d! ' cto' t attN RTI <I: via wiG a 1ked aCUJa!JH te111puatm */Vhle t.. .. l!~ctolaCU a!JHthH ('ec) 

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V\*hle T, .. • celtllg t:ttelllpuatue (C) 

T,. • <til II~ ll<tll I:IIIJ.':' 1.1t11r. (C) 

coutectue po11m oTIU •eat I? t:aH ra' t:V\1) 

H • h._;J .t010?III)g .. )We bp Ofne l II) 

DIIIH • 0.18 

'DIIIH > 0.18 

I• l<tdl'lldl$tno: 'I'I"Ctll U e pltllH CU,IIhe b 1U e~ct)f ll) 

con vee he Heat R$1&a•e RaU OllculaUon 

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a - •eat IH:<I6e "'' one Ill! ;J:ItV) 

J, • coutectue hat1e1:a.e ~~ 1tac1m 

a,- reo •:V\* 

I 

1000.00 lo:'.:V 

10.00 II 

13.00 II 

86.00 ' f 

5.00 (Jo\ 0 

n.ool·, 

0.70 

0.67 

12 

18.00 ' f 

947.82 6t.A:t 

)0SM 

, ... ,.,. .. ~ 

MOO 'C 

09800 K 

10 " 
11-16

Radial Distameto CeilinA ~iAtt Ratio calculation 

r/H = 0.77 riH > 0.15 

>0.15 

T,., . T,. = 

T,., . T,. = 

T,.,= 

50.92 

538 ((0<*:r'2/3)1H 

50.92 

75.92 ('1:) 

Cei li rg Jet Velocity Calculation 

u1 .. = o.g6 (0/Hf .:t 

u1,. = (0.1g5 o":l H' Y 'II 

Where u,., =ceiling jet ttelocity(nv'sec) 

0 =heat release r.m ofthe fire (kVll) 

H =height of ceiling above top of fuel (m) 

<0.15 

i:lr r/H = 0.15 

i:lr r/H > 0.15 

r= radial distance from the plume centertine to 1he detector (m) 

Radial Distameto Ceiling ~igtt Ratio calculation 

r/H = 0.77 riH > 0.15 

>0.15 1.53 <0.15 

U1,. = (0.1g5 0"1.0 H"1/2)t"(5.6) 

U1,. = 1.533 mJsec 

Smd<e Detector ~sponse Time CalcUaticn 

IIOTE: tft.,ot ..... ton = '11UM''Detettor does not attivate 

13428 

607 

METHOD ::O~~ •• ~~~,~~~~ ;_; .. ;; :;:~ ... !!;;:;: -- ;;.-~ ... •i!!!thi!i! """" ~~·M;:.,. ;:i!:;;.,. ~ • .=;;·- r.5::!~ .• ;_:r;"'=' ;i.;;;·oor ;;;;;:;<;;,<~i;;;;!:ii!:£::;::_i . ~ t.-.. ....... , = t d + tq 

VlJhere t. ........... ~ = detectoracthmion time (sec) 

tp, =transpon lag time of plume (sec) 

tt = transpon lag time of ceiling jet (sec) 

Transport Lag Time of Plume CalcUaticn 

t

11= C11 (H)"'"..I(O). ".. 

VlJhere ~ =transpon lag time of plume (sec) 

Cp, = plume lag time constant 

H =height of ceiling above top of fuel (m) 

0 =heat release r.m ofthe fire (kVll) 

t 11 = 0.42 seo 

Transport Lag Time of Ceilirg Jet CalcUaticn 

Where tt = transpon lag time of ceiling jet (sec) 

C..1 =ceiling jet lag time constant 

r= radial distance from the plume centertine to 1he detector (m) 

H =height of ceiling above top of fuel (m) 

0 =heat release r.m ofthe fire (kVll) 

t q = 0.32 sec 

Smd<e Detector ~sponse Time CalcUaticn 
11-17

b:•:~• n= X H •'

3

/0113 

Where ~lt ~• n= detector activation time (sec) 

X= 4.61o·•y+ 2.71o·•sy 

H =height of ceiling above top of fuel (fO 

Q = heat releaser ate from steady fire (Btu/sec) 

Where Y= lLTc HS.'

3/ Qz3 

lLTc = ~mperature rise of gases under the ceiling for smoke detector to activate (°F) 

Before esti matinA srro ke detector responseti me, stratification effeds ccn be calculcted. 

NFPA 928,2000 Edition, Sedion A.3.4 pro'Jidesfollov.tng correlation to estimate smoke 

strctification in a compartment. 

Where H·~~~ = the m~imum ceiling clearance to which a plume can rise (ft) 

Oc =convective portion of the heat releaser ate (Btutsec) 

1LT1ooc =difference in Wmper ature due ro 1ire beblueen the fuel location and ceiling level (°F) 

Convective Heel Release Rate Calculation 

Oc=01c 

Where 

Oc= 

Oc =convective portion of the heat releaser ate (Btutsec) 

Q = heat releaser ate of the fire (BbJ/sec) 

1c = convective heat releas rate fraction 

663.47 Btu-'s ec 

Difference in Temperature Due to Fire Bet-...eenthe Fuellocction end Ceiling le>RI 

lLT1<>c = 1300 O:z3 /HS.') 

Where lLT1<>c =difference in Wmper ature due ro 1ire beblueen the fuel location and ceiling level (°F) 

Oc =convective portion of the heat releaser ate (Btuo'sec) 

H =ceiling height above the fire source (ft) 

lLT1<>c = 1375.90 •F 

Smoke Stratification Effects 

H•o~~ = 74 al-s /lLT1<>c3.-s 

13.03 ft 

In this case the highest point of smoke rise is estimated to be 

Thus, the smoke V\Ould be expected to reach the ceiling mounted smoke detector. 

y =A.T<o Hm / Qt'$ 

Y= 13.41 

X= 4.6 10·" Y: + 2.7 10· t> Y$ 

X= 0.08 

Smoke OS ector Response Time Calculation 

b:t:~• n= X H •'J/011$ 

13.03 ft 
11-18

Su mmarv of Result 

Calc:ulction Method 

METHOD OF ALPERT 

METHOD OF MOWRER 

Smoke Detector Res onse Time sec 

0.42 

0.74 

0.26 
11-19

Example Problem 11.12-2

Problem Statement

During a routine inspection, an NRC resident inspector finds a stack of 4-ft-high wooden pallets

left in the NPP after a recent MOV modification. When the inspector questions the licensee about

this transient combustible, the licensee assures the inspector that if the transient ignited, the smoke

detection system would alarm in less than 1 minute.

The SFPE Handbook provides test data for a stack of 4-ft-high wooden pallets, from which the HRR

can be estimated at 3.5 MW.

The compartment has a 25-ft ceiling with the smoke detectors spaced 30 ft on center. The pallets

are located in the worst position (i.e., in the center of four smoke detectors).

How long does it take the smoke detector to alarm?

Solution

Purpose:

(1) Determine the response time of the smoke detector for the fire scenario.

Assumptions:

(1) The fire is steady-state.

(2) The forced ventilation system is off.

(3) There is no heavily obstructed overhead.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 10_Detector_Activation_Time.xls (click on Smoke_Detector)

FDT Input Parameters: s

-Heat Release Rate of the Fire = 3,500 kW

-Ceiling Height (H) = 25 ft

-Radial Distance from the Plume Centerline to the Smoke Detector (r) = 21.2 ft

Results*

Heat Release

Rate (kW)

Smoke Detector A Rctivation Time (t ) (sec)

3,500

Method of Alpert Method of Mowrer Method of Milke

0.55 1.27 0.67

*see spreadsheets on next page

Therefore, it can be assumed that the smoke detectors would alarm within 1 minute.
11-20

Spreadsheet Calculations

FDT : 10_Detector_Activation_Time.xls (Smoke_Detector) s

CHAPTER 11. ESTIMATIIIG SMOKE DETECTOR RESPOIISE TIME 

Version 18050 

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IIIPUT PARAMETER S 

MtR~ l:aH Ra' OT1U Fll ~ Q) (S'<HI{ S'tl•) 

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$IIOI;t Ot.cbl P,t$p0Ut ThH lUI? X P.T~ 

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COUtt CUJe Heat P.H:aH P,'l. Fl<t:tba !J" PIUIIt l eg Tille Coutlat(Ct/ (EcptiiiiUtlll{ ebnii ii H~ 

Ct l1119 Jt tl<t.J Tlllt COUt.'llt(C,.) p•lhH lt.'lll{ O:.IIIIHd) 

nmpH'11U P.la 01Gaa$ UUIH1U Ct l'-9 ) 

D 1 Sill ote De • ctH 1:u\c1va• 

r!H = +:+.35 

ESTIMATING SMOKE DETECTOR RESPONSE TIME 

METHOD OF ALPERT 

~ ... "' !§~~,.~~~~, !:;: ~· ""!1' >- "" ===a t .. ,...,_. (P.Ttte ,,.,, (. (r,. -T4l/(r,. -T- .. ..-;» n ~me Qed a sHnH 6mote d! ' cto' t attN RTI <I: via wiG a 1ked aCUJa!JH te111puatm */Vhle t.. .. l!~ctolaCU a!JHthH ('ec) 

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C\lllln}l tnmpH\'I tur~ 011cu1a1on 

T,. - T,. • 16.9 Q;,J> Jt{ 

T,. - T,. • 5.38 · JH 

V\*hle T, .. • celtllg t:ttelllpuatue (C) 

T,. • <til II~ ll<tll I:IIIJ.':' 1.1t11r. (C) 

coutectue po11m oTIU •eat I? t:aH ra' t:V\1) 

H • h._;J .t010?III)g .. )We bp Ofne l II) 

DIIIH • 0.18 

'DIIIH > 0.18 

I• l<tdl'lldl$tno: 'I'I"Ctll U e pltllH CU,IIhe b 1U e~ct)f ll) 

con vee he Heat R$1&a•e RaU OllculaUon 

0 <• ), 0 

1/Vhle 0 < • C0Ulee111e p011m OTIU •eat te IMH ra ' t:V'V) 

a - •eat IH:<I6e "'' one Ill! ;J:ItV) 

J, • coutectue hat1e1:a.e ~~ 1tac1m 

Q , • 2450 •:V\* 

I 

39:10.00 t:'.:V 

:1.:0 11 

: S.OO II 

86.00 ' f 

5.00 (Jo\ 0 

n.ool·, 

0.70 

0.67 

12 

18.00 ' f 

3317.37 6t.A:t 

.... 

,.,. ,.,. .. ~ 

MOO 'C 

09800 K 

10 " 
11-21

Radial Distameto CeilinA Heit:~tt Ratio calculation 

r/H= 0.85 riH >0.15 

>0.15 

T,., . T,. = 

T,., . T,. = 

T,.,= 

36.99 

538 ((0<*:r'213)1H 

36.99 

61.99 ('1:) 

Cei li rg Jet Velocity Calculation 

u1 .. = o.g6 (0/Hf .:t 

u1,. = (0.1g5 o":l H' Y 'II 

Where u,., =ceiling jet ttelocity(nv'sec) 

0 =heat release r.m ofthe fire (kVll) 

H =height of ceiling above top of fuel (m) 

<0.15 

i:lr r/H = 0.15 

i:lr r/H > 0.15 

r= radial distance from the plume centertine to 1he detector (m) 

Radial Distameto Ceiling Heigtt Ratio calculation 

r/H= 0.85 riH >0.15 

>0.15 1.73 <0.15 

U1,. = (0.1g5 0"1.0 H"1/2)t"(5.6) 

U1,. = 1.726 mJsec 

Smd<e Detector ~sponse Time CalcUaticn 

IIOTE: tft.,ot ..... ton = '11UM''Detettor does not attivate 

104Dg 

7.41 

METHOD ::O~~ •• ~~~,~~~~ ;_; .. ;; :;:~ ... !!;;:;: -- ;;.-~ ... •i!!!thi!i! """" ~~·M;:.,. ;:i!:;;.,. ~ • .=;;·- r.5::!~ .• ;_:r;"'=' ;i.;;;·oor ;;;;;:;<;;,<~i;;;;! -t:ii!:£::;::_i . ~ t.-.. ....... , = t d + tq 

VlJhere t. ........... ~ = detectoracthmion time (sec) 

tp, =transpon lag time of plume (sec) 

tt = transpon lag time of ceiling jet (sec) 

Transport Lag Time of Plume CalcUaticn 

t

11= C11 (H)"'"..I(O). ".. 

VlJhere ~ =transpon lag time of plume (sec) 

Cp, = plume lag time constant 

H =height of ceiling above top of fuel (m) 

0 =heat release r.m ofthe fire (kVll) 

t 11 = 0.66 seo 

Transport Lag Time of Ceilirg Jet CalcUaticn 

Where tt = transpon lag time of ceiling jet (sec) 

C..1 =ceiling jet lag time constant 

r= radial distance from the plume centertine to 1he detector (m) 

H =height of ceiling above top of fuel (m) 

0 =heat release r.m ofthe fire (kVll) 

t q = 0.61 sec 

Smd<e Detector ~sponse Time CalcUaticn 
11-22

b:•:~• n= X H •'

3

/0113 

Where ~lt ~• n= detector activation time (sec) 

X= 4.61o·•y+ 2.71o·•sy 

H =height of ceiling above top of fuel (fO 

Q = heat releaser ate from steady fire (Btu/sec) 

Where Y= lLTc HS.'

3/ Qz3 

lLTc = ~mperature rise of gases under the ceiling for smoke detector to activate (°F) 

Before esti matinA srro ke detector responseti me, stratification effeds ccn be calculcted. 

NFPA 928,2000 Edition, Sedion A.3.4 pro'Jidesfollov.tng correlation to estimate smoke 

strctification in a compartment. 

Where H·~~~ = the m~imum ceiling clearance to which a plume can rise (ft) 

Oc =convective portion of the heat releaser ate (Btutsec) 

1LT1ooc =difference in Wmper ature due ro 1ire beblueen the fuel location and ceiling level (°F) 

Convective Heel Release Rate Calculation 

Oc=01c 

Where 

Oc= 

Oc =convective portion of the heat releaser ate (Btutsec) 

Q = heat releaser ate of the fire (BbJ/sec) 

1c = convective heat releas rate fraction 

2322.16 Btu-'s ec 

Difference in Temperature Due to Fire Bet-...eenthe Fuellocction end Ceiling le>RI 

lLT1<>c = 1300 O:z3 /HS.') 

Where 

lLT1<>c = 

lLT1<>c =difference in Wmper ature due ro 1ire beblueen the fuel location and ceiling level (°F) 

Oc =convective portion of the heat releaser ate (Btuo'sec) 

H =ceiling height above the fire source (ft) 

1036.53 •F 

Smoke Stratification Effects 

H•o~~ = 74 al-s /lLT1<>c3.-s 

25.05 ft 

In this case the highest point of smoke rise is estimated to be 25.05 tt 

Thus, the smoke V\Ould be expected to reach the ceiling mounted smoke detector. 

y =A.T<o Hm / Qt'$ 

Y= 17.30 

X= 4.6 10·" Y: + 2.7 10· t> Y$ 

X= 0.14 

Smoke OS ector Response Time Calculation 

b:t:~• n= X H •'J/011$ 
11-23

Su mmarv of Result 

Calc:ulction Method 

METHOD OF ALPERT 

METHOD OF MOWRER 

Smoke Detector Res onse Time sec 

0.55 

1.27 

O.S7 
11-24

Example Problem 11.12-3

Problem Statement

During a triennial inspection, an NRC inspector discovers that every other smoke detector

has inadvertently been painted and is not functional. The detection system in the compartment

is single-zoned to arm a pre-action sprinkler system. The detectors are 20 ft on center. The ceiling

is 23 ft. The sprinkler system uses 165 °F sprinklers, 10 ft on center, 4 inches from the ceiling.

The licensee states that even with half the smoke detectors inoperable, a smoke detector would

alarm and charge the pre-action system before a quick-response link-type sprinkler head fuses.

The expected fire in the compartment is approximately 750 kW. Is the licensee’s statement true?

Solution

Purpose:

(1) Determine the response time of the smoke detector for the fire scenario.

(2) Determine the response time of the sprinkler system.

Assumptions:

(1) The fire is steady-state.

(2) The forced ventilation system is off.

(3) There is no heavily obstructed overhead.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 10_Detector_Activation_Time.xls (click on Smoke-Detector)

FDT Input Parameters: s

-Heat Release Rate of the Fire = 750 kW

-Ceiling Height (H) = 23 ft

-Radial Distance from the Plume Centerline to the Smoke Detector (r) = 20 ft

(b) 10_Detector_Activation_Time.xls (click on Sprinkler)

FDT Input Parameters: s

-Heat Release Rate of the Fire = 750 kW

-Select Quick Response Link

-Select Ordinary

-Ceiling Height (H) = 23 ft

-Radial Distance from the Plume Centerline to the Sprinkler (r) = 7.1 ft

Results*

Heat Release

Rate (kW)

Smoke Detector A Rctivation Time (t ) (sec)

3,500

Method of Alpert Method of Mowrer Method of Milke

2.0 1.94 6.0

The sprinkler heads do not activate.

*see spreadsheet on next page

Therefore, the licensee’s statement is true; however, the non-activation of the sprinkler heads

should be of great concern.
11-25

Spreadsheet Calculations

(a) FDT : 10_Detector_Activation_Time.xls (Smoke_Detector) s

CHAPTER 11. ESTIMATIIIG SMOKE DETECTOR RESPOIISE TIME 

Va-sion 18050 

P.'lr.lm $t$r• •hOUid b$ •P$~Ihd O:•lll v Ill THE v Ell(•\~' Ill PUT PARAMETER &:•XES. 

Ill PUT PARAMETER S 

HMtR$I:aH fta' one Fir~ Q) ·ad{ S'tl' ) 

R<t:ll.'ll01$tUO: b 1U O.'cbl (f) ''HtJH IIIOie Q<U 0.707 I1J2~ T1U l>bd $I).'ICII(I"' 

HH;J.t01Cel-.g .. )Q.Tt TCt) OTFHI (H) 

.A.cUJa!JH nmpe ratlre orue 11 te oe•ctif fl..,".-) 

$IIOI;e Oe,cbl P,t$pOUe TIIH lUI? X P.T~ 

;:.JIIbl:.t :. tnm~ rat. te (r,) 

COUlt CUJe Heat P.el:<16e ~'l · fl<t:tbl !J~ 

tlllll' l t'') Tlolf CvHl-tll\.C&i (0JI'<'II11t'll-tllf 0 '<'1i:' llll II '<' ~ 

Ce 11119 J etl<t.J Tllle COUt.'llt(C,.) pe lhH lt.'lll{ O:.IIIIHd) 

nmpH'11U P.la 01G<aa$ UUIH1U Ce ll)g ) 

Dl 11 te oe• ctH t u\c1va• 

r!H = +:+.37 

ESTIMATING SMOKE DETECTOR RESPONSE TIME 

METHOD OF ALPERT 

~ ... ~t "' !§~~,.~~~~, !:;: ~· ""!1' >- "" ===a t .. ,...,_. (P.Ttte ,,.,, (. (r,. -T4l/(r,. -T- .. ..-;» n ~me Qed a sHnH 6mote d! ' cto' t attN RTI <I: via wiG a 1ked aCUJa!JH te111puatm 

*/V hle t.. .. l!~ctolaCU a!JHthH ('ec) 

RTI• <I!~ iiUp m Olle •<I!X ~~~e¢) • 

, ,. - o: lllt et e•,c r {liMO) 

T, .. - ce1111 g t:tte111pe1atue (C) 

,. •<rll htall' '"' ~l.'l111 1? (C) 

T,.,, .. - · aCUJalm ''11pua1m T<I!~ cb l (C) 

C\lllln}l tnmpH\'I tur~ 011cu1a1on 

T,. - T,. • 16.9 Q;,J> Jt{ 

T,. - T,. • 5.38 · JH 

V\* hle T, .. • celtllg t:ttelllpuatue (C) 

,. •<rll htall, ,ll ~l.'l111 te (C) 

~ • C0Ulee111e p011m OTIU •eat te IMH ra ' t:V\1) 

H • h~·t O? IIItg .. )We bp OTIUI @II) 

DIIIH • 0.18 

'DIIIH > 0.18 

I• l<tdl'lldl$tl10: 1'lCtll U e pi,IJH CU,III&e b 1H de~cbl @ll) 

con vee he Heat Rel&a•e RaU OllculaUon 

Q , • ) , Q 

*/V hle ~ • coutectue po11m oTIU •eat te l:aH ra ' t:v·v;. a • •eat 1e1:ase "'' 011u Ill! ;J:\t\1) 

J<.• cou,ectue uat1e1:aa ~~ 1tac1m 

Oo • 525 •:V\* 

I 

i50.00 •:'.N 

:0.00 II 

:J.OO II 

86.00 ' f 

5.00 {lll•lt O " 

n.ool·, 

0.70 

o.o; 

12 

18.00 *f 

7 10.87 6t.Ae 

6.10m 

101m 

3000 'C 

MOO 'C 

aooK 

10 " 
11-26

Radial Distameto CeilinA ~iAtt Ratio calculation 

r/H= 0.87 riH >0.15 

>0.15 

T,., . T,. = 

T,., . T,. = 

T,.,= 

14.g7 

538 ((OcA-:r'2/3)1H 

14.g7 

39.97 ('1:) 

Cei li rg Jet Velocity Calculation 

u1 .. = o.g6 (0/Hf .:t 

u1,. = (0.1g5 o":l H' Y 'II 

Where u,., =ceiling jet ttelocity(nv'sec) 

0 =heat release r.m ofthe fire (kVll) 

H =height of ceiling above top of fuel (m) 

<0.15 

i:lr r/H = 0.15 

i:lr r/H > 0.15 

r= radial distance from the plume centertine to 1he detector (m) 

Radial Distameto Ceiling ~igtt Ratio calculation 

r/H= 0.87 riH >0.15 

>0.15 1.04 <0.15 

U1,. = (0.1g5 0"1.0 H"1/2)t"(5.6) 

U1,. = 1.040 mJsec 

Smd<e Detector ~sponse Time CalcUaticn 

IIOTE: tft.,ot ..... ton = '11UM''Detettor does not attivate 

42.83 

456 

METHOD ::O~~ •• ~~~,~~~~ ;_; .. ;; :;:~ ... !!;;:;: -- ;;.-~ ... •i!!!thi!i! """" ~~·M;:.,. ;:i!:;;.,. ~ • .=;;·- r.5::!~ .• ;_:r;"'=' ;i.;;;·oor ;;;;;:;<;;,<~i;;;;! -t:ii!:£::;::_i . ~ t.-.. ....... , = t d + tq 

VlJhere t. ........... ~ = detectoracthmion time (sec) 

tp, =transpon lag time of plume (sec) 

tt = transpon lag time of ceiling jet (sec) 

Transport Lag Time of Plume CalcUaticn 

t

11= C11 (H)"'"..I(O). ".. 

VlJhere ~ =transpon lag time of plume (sec) 

Cp, = plume lag time constant 

H =height of ceiling above top of fuel (m) 

0 =heat release r.m ofthe fire (kVll) 

t 11 = 0.99 seo 

Transport Lag Time of Ceilirg Jet CalcUaticn 

Where tt = transpon lag time of ceiling jet (sec) 

C..1 =ceiling jet lag time constant 

r= radial distance from the plume centertine to 1he detector (m) 

H =height of ceiling above top of fuel (m) 

0 =heat release r.m ofthe fire (kVll) 

t q = 0.95 sec 

Smd<e Detector ~sponse Time CalcUaticn 
11-27

b:•:~• n= X H •'

3

/0113 

Where ~lt ~• n= detector activation time (sec) 

X= 4.61o·•y+ 2.71o·•sy 

H =height of ceiling above top of fuel (fO 

Q = heat releaser ate from steady fire (Btu/sec) 

Where Y= lLTc HS.'

3/ Qz3 

lLTc = ~mperature rise of gases under the ceiling for smoke detector to activate (°F) 

Before esti matinA srro ke detector responseti me, stratification effeds ccn be calculcted. 

NFPA 928,2000 Edition, Sedion A.3.4 pro'Jidesfollov.tng correlation to estimate smoke 

strctification in a compartment. 

Where H·~~~ = the m~imum ceiling clearance to which a plume can rise (ft) 

Oc =convective portion of the heat releaser ate (Btutsec) 

1LT1ooc =difference in Wmper ature due ro 1ire beblueen the fuel location and ceiling level (°F) 

Convective Heel Release Rate Calculation 

Oc=01c 

Where 

Oc= 

Oc =convective portion of the heat releaser ate (Btutsec) 

Q = heat releaser ate of the fire (BbJ/sec) 

1c = convective heat releas rate fraction 

497.61 Btu-'s ec 

Difference in Temperature Due to Fire Bet-...eenthe Fuellocction end Ceiling le>RI 

lLT1<>c = 1300 O:z3 /HS.') 

Where 

lLT1<>c = 

lLT1<>c =difference in Wmper ature due ro 1ire beblueen the fuel location and ceiling level (°F) 

Oc =convective portion of the heat releaser ate (Btuo'sec) 

H =ceiling height above the fire source (ft) 

438.95 •F 

Smoke Stratification Effects 

H•o~~ = 74 al-s /lLT1<>c3.-s 

23.05 ft 

In this case the highest point of smoke rise is estimated to be 23.05 tt 

Thus, the smoke V\Ould be expected to reach the ceiling mounted smoke detector. 

y =A.T<o Hm / Qt'$ 

Y= 42.04 

X= 4.6 10·" Y: + 2.7 10· t> Y$ 

X= 0.81 

Smoke OS ector Response Time Calculation 

b:t:~• n= X H •'J/011$ 
11-28

Su mmarv of Result 

Calc:ulction Method 

METHOD OF ALPERT 

METHOD OF MOWRER 

Smoke Detector Res onse Time sec 

1.99 

1.94 

5.93 
11-29

(b) FDT : 10_Detector_Activation_Time.xls (Sprinkler) s

CHAPTER 10o ESTIMATING SPRINKLER RESPONSE TIME 

Ve<Sion 180So0 

The following calculations estima!Jl sprinkler acti\G1ion time. 

Parameters in YELLOW CELLS are Ertered by the User. 

Parameters in GREEN CELLS are Automatically Selectedfromthe ORO P DOWN M ENUforthe Spriri<ler Selected. 

All subsequent oUiput \Glues are calcolat»ld bythe spreadsheet and based on wlues speci1ied in the input 

p3~mow."". This spro3dshoot is proto~d and soeuro 11) avoid oiTO"" duo to a wrong or.tryin a eoll(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

Heat Release Rate ofthe Fire (Q)(St»lady StJte) 

Sprinkler Response Time Index (RTI) 

.Acthmion T empel'3ture of the Sprinkler (T.,.,..,.,,..) 

Height of Ceiling above Top of Fuel (H) 

Radial Distance 10 the Detector (r) ,..nevermore than 0.707 or 1/2\Q oflhe list»ld spacinQ"" 

Anbient Air Temper.Jture (T,.) 

Convective Heat Release Rate Fraction (1,) 

riH = 0.31 

Sprinkler T we 

750.00 t; 

34 < 

165 ° 

23.0011 

7.1011 

77.00 ° 

0.70 

I Calculate II 

1 389 ·c 

7 .01111 

Z98.00 K 

to desired sp-iri<lertype then Click on selecticn 

Ordinary 

lntennediate 

High 

ertra high 

\krye:.tra high 

Ultrahigh 

Ultrahigh 

User S eciied \t.tlue 

135to 170 

175to 225 

250to 300 

325to 375 

400to 475 

500to 575 

650 

Generic Tempe mu re 

Ratin s •F 

165 

212 

275 

350 

450 

550 

550 

Ent:er v.tlu e 

R~ "t rw:~: .:U~'\t:~:.: prrN~ '':t1'\11 :;H~-.:>Jo, 0 " adtbr~ N~: VII .'~P ct~-t:.:mA:;~-.;:,l:f:¢1"\ o.:Jncy. M>1=h.t:<'ft:. 11111;:. P;:<;;~07. 

* Ncte: The actLB I temperature rating shoU d be used when the value is avail able. 

Select Sprinkler Cl assifi cation 

i Sts'nar, I ·I 

Scroll to desired sprinkler class 

hen Click on selection 
11-30

ESTIMATING SPRINKLER RESPONSE TIME 

l'l: 'I! rw:.:: Nl"PA ,:it? ro;tK.:t -..~ .'·fil'.'ldOO t 7 \lr.o. 5:!/t\lfi. CJ. Pil'g? 3-'14>. 

b:t cn = (RTI(v'-'~~)(ln (T•~•· T ~T ~tl· T4>:1t:.)l:t\)) 

Where b :t;.)l:n= sprinkler activation response time (sec) 

RTI = spriri< ler response time index (m-sec) 1

'

2 

u~• =ceiling jet velocity (m/sec) 

Tid= ceiling jettemperature ( 0C) 

~ = ambient air temper ab.Jre (°C) 

~: t:.)l n = activation temperature of sprinkler (°C) 

Ceiling Jet Temperature Calculation 

T1d· To)= 16.9 (Oe)..:>s/H :.>J 

Z') T1d· T .)= 5.33 (Oclr) .+1 

Where T•~• =ceiling jettemperature ( 0C) 

T.) = ambient air temper ab.ue (°C) 

for r/H = 0.18 

for r/H > 0.18 

Oe = convective portion of the heat release rate (kW) 

H =height of ceiling above top offuel(m) 

r = radial distance from the plume centerline to the sprinkler (m) 

Con>.Ective Heat Release Rete Calculction 

Oe=1c 0 

Where Oe = convective portion of the heat release rate (kW) 

Q = heat releaser ate of the fire (kW) 

Oe= 

1e =convective heat release rate fraction 

525kW 

Radial Dislanceto Ceiling Height Rctio Calculation 

r/H = 0.31 uH > 0.15 

Tr~•· T ~= {5.38 (Qc/r)'\2.<3}.+1 

Trd· T ~= 29.85 

Trd= 54.85 (•c) 

Ceiling Jet Velocity Calculation 

'-'~•= 0.93 (Q/H) 113 

'-'~•= (0.195 0 113 11')tr ~ 

Where U~tl =ceiling jet velocity (m/sec) 

Q = heat releaser ate of the fire (kW) 

H =height of ceiling above top offuel(m) 

for r/H = 0.15 

for r/H > 0.15 

r = radial distance from the plume centerline to the sprinkler (m) 

Radial Distanceto Ceiling Height Rctio Calculation 

r/H = 0.31 r.+l > 0.15 

'-'~•= (0.195 0111/3 Hll112)/1"'516 

2.485 m/sec 
11-31

Sprinlder Actiwtion Time Calculction 

1«t cn = (RTI.(v'-'~~)(ln (T•~•· T ~T ~•· ~: ~• .\)) 

tMt<Ahn = #NUM! sec 

!!The sprinlder Wll respond in approxi mctey #NUM! minutes 

NOTE: If t,., " ' •"- "'NUM'' Sl>rinkler does not activate 

[Mti.t,M 

The above calculations are based on principles developed in the NFPA Fire Protection Hand book 

19hEdition, 2003. Calculations are based on certain assumptions and have inherent limitations. 

The results of such calculations may or may not have reasonable predictive capabilities for a given 

situation, and should only be interpreted by an informed user. 

Anhough each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolute guarantee of the accuracy of these calculations. 

Arfl/ questions. comments, concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or mxs3@nrc.gov. 

12-1

CHAPTER 12. ESTIMATING HEAT DETECTOR RESPONSE TIME

12.1 Objectives

This chapter has the following objectives:

• Explain where heat detectors are located.

• Identify the various types of heat detectors and how they work.

• Describe how to calculate the activation time of a heat detector.

12.2 Introduction

Heat detectors are one of the oldest forms of automatic fire detection devices, and they typically

have the lowest false alarm rate of all automatic fire detection devices. Nonetheless, they are

generally the slowest to detect fires because they do not detect smoke. Rather, they respond either

when the detecting element reaches a predetermined fixed temperature or when the temperature

changes at a specified rate. Thus, heat detectors usually do not provide enough early warning in

case of a life-threatening situation. As a result, heat detectors are best suited for fire detection in

a small confined space where rapidly building high-heat-output fires are expected, in areas where

ambient conditions would not allow the use of other fire detection devices, or where speed of

detection is not a primary consideration.

Heat detectors are generally located on or near the ceiling, where they can respond to the

convected thermal energy of a fire. They may be used in combination with smoke detectors, since

smoke detectors usually activate before the flames and heat would are sufficient to alarm the heat

detector. In general, heat detectors are designed to operate when heat causes a prescribed

change in a physical or electrical property of a material or gas.

The following excerpts are from the procedure specified by Underwriters’ Laboratories, Inc., for

using thermal detectors in automatic fire detection systems. Notice that to prevent false alarms,

detectors should be installed only after considering the limitation on their operational rating and the

prevalent ceiling temperatures. For example, ordinary detectors rated from 57–74 °C (135–165 °F)

should be installed only where ceiling temperatures do not exceed 37.7 °C (100 °F).

12.3 Underwriters’ Laboratories, Inc., Listing Information for Heat-Detecting

Automatic Fire Detectors

“A heat-detecting type of automatic fire detector is an integral assembly of heat-responsive

elements and non-coded electrical contacts, which function automatically under conditions of

increased air temperature.” Listing under this heading applies to fire alarm heat detectors only and

not to wiring or other appliances of which they form a part. Fire alarm heat detectors are of the

fixed-temperature, combination fixed-temperature, and rate-of-rise or rate compensation types.

There are basically two types: (1) spot-type is one in which the thermally sensitive element is a

compact unit of small area, and (2) line-type is one in which the thermally sensitive element is

continuous along the line. These heat detectors have been investigated for indoor use only unless

otherwise indicated in the individual listing.
12-2

Ordinarily, heat detectors are intended for locations where normal ceiling temperatures prevail

below 37.7 °C (100 °F). Locations where ceiling temperatures are likely to be unduly high, from

sources of heat other than fire conditions such as boiler rooms, dry kilns, etc., demand special

consideration and selection of heat detectors operating normally at higher temperatures, and which

are capable of withstanding high temperatures for long periods of time.

Care should be exercised to select heat detectors having the proper temperature rating to guard

against false alarms from premature operation. These detectors are intended to be installed in

accordance with NFPA 72E-Automatic Fire Detectors. For ceiling temperatures exceeding 37.7 °C

(100 °F), install 57.2–73.8 °C (135–165 °F) (ordinary) rating thermostats. For ceiling temperatures

exceeding 37.7 °C (100 °F), but not 65.5 °C (150 °F), install 79.4–107.2 °C (175–225 °F)

(intermediated) rating thermostats. For ceiling temperatures exceeding 65.5 °C (150 °F), but not

107.2 °C (225 °F), install 121.1 to 148.8 °C (250–300 °F) (high) rating thermostats. For ceiling

temperatures exceeding 107.2 °C (225 °F), but not 148.8 °C (300 °F), install 162.7–182.2 °C

(325–360 °F) (extra high) rating thermostats.

Low-degree rated heat detectors are intended only for installation in areas having controlled

temperature conditions at least -6.6 °C (20 °F) below rating. The spacings specified are for flat,

smooth ceiling construction of ordinary height, generally regarded as the most favorable condition

for distribution of heated air currents resulting from a fire. Under other forms of ceiling construction,

reduced spacings may be required.

The fire tests conducted to determine the suitability of the spacings are conducted in an 18.3 x 18.3 m

(60 x 60 ft) room having a 4.8-m (15-ft, 9-in.) high smooth ceiling and minimum air movement.

The test fire (denatured alcohol) is located approximately 0.91 m (3 ft) above the floor and is of a

magnitude so that sprinkler operation is obtained in approximately 2 minutes. For comparative

purposes, automatic sprinklers rated at 71.7 °C (160 °F) are installed on a 3.05 x 3.05 m (10 x 10 ft)

spacing schedule in an upright position with the deflectors approximately 17.5 cm (7 in) below the

ceiling. At the maximum permissible spacing for the heat detectors, they must operate prior to

operation of the sprinklers.

The placement and spacing of heat detecting devices should be based on consideration of the

ceiling construction, ceiling height, room or space areas, spaced subdivisions, normal room

temperature, possible exposure of the devices to abnormal heat (such as uninsulated steam pipes)

or to draft conditions likely to be encountered at the time of a fire.

12.4 Operating Principle of Heat Detectors

Spot type heat detectors respond to temperature changes in the surrounding environment. They

are designed to respond to the convected thermal energy of a fire. They detect at either a

predetermined fixed temperature or at a specified rate of temperature rise. In general, a heat

detector is designed to sense a prescribed change in a physical or electrical property of its material

when exposed to heat.
12-3

12.4.1 Fixed-Temperature Heat Detectors

Fixed-temperature detectors are intended to alarm when the temperature of their operating

elements reaches specific points. The air temperature at the time of operation may be higher than

the rated temperature due to the thermal inertia of the operating elements. This condition is called

thermal lag. Fixed-temperature heat detectors are available to cover a wide range of operating

temperatures from 57 °C (135 °F) and higher. Higher temperature detectors are sometimes

necessary so that detection can be provided in areas normally subjected to high ambient (nonfire)

temperatures. Fixed-temperature heat detectors are manufactured in seven temperature range

groups, and the proper detector is selected based on the highest ambient temperature of the room

for which it is designed. Fixed-temperature detectors are available in several types.

12.4.1.1 Fusible-Element Type

One type of fusible-element spot detector is the eutectic (fusible) metal type. Eutectic metal

employs a mixture of either bismuth, lead, tin or cadmium which melts at a predetermined

temperature. Eutectic metals that melt rapidly at a predetermined temperature are used to actuate

the operating elements of the heat detector. When the element fuses (i.e., melts), the spring action

closes contacts and initiates an alarm. Devices using eutectic elements cannot be restored. When

their element fuses, alarms are signaled by various mechanical or electrical means (typically by a

closed set of contacts).

12.4.1.2 Continuous Line Type

One type of line detector uses a pair of wires in a normally open circuit enclosed in a braided

sheath to form a single-cable assembly. When the predetermined temperature is reached, the

insulation, which holds the conductors apart melts, and the two wires come in contact which

initiates the alarm. The fused section of the cable must be replaced to restore the system.

Alternatively, this type of detector may use a stainless steel capillary tube containing a coaxial

center conductor separated from the tube wall by a temperature-sensitive glass semiconducting

material. As the temperature rises, the semiconductor decreases and allows more current to flow,

thereby initiating the alarm.

12.4.1.3 Bimetallic Type

These spot detectors are generally of two types, including (1) the bimetal strip and (2) the bimetal

snap disc. As it is heated, the bimetal strip deforms in the direction of the contact point. The

operating element of a snap disc device is a bimetal disc composed of two metals with different

thermal growth rates formed into a concave shape in its unstressed condition. Generally, a heat

detector is attached to the detector frame to speed the transfer of heat from the room air to the

bimetal. As the disc (not part of the electrical circuit) is heated, the stresses developed in the two

different metals cause it to suddenly reverse the curvature and become convex. This provides a

rapid positive action that closes the alarm contacts. These devices are typically self-restoring after

heat is removed.
12-4

12.4.2 Rate Compensation Heat Detectors

These spot type detectors respond when the temperature of the air surrounding the detector

reaches a predetermined temperature, regardless of the rate of temperature rise. A typical example

is a spot-type detector with a tubular casing of metal that tends to expand lengthwise as it is heated,

and an associated contact mechanism that will close at a certain point in the elongation. A second

metallic element inside the tube exerts an opposing force on the contacts, tending to hold them

open. The forces are balanced so that, with a slow rate of temperature rise, there is more time for

heat to penetrate to the inner element. This inhibits contact closure until the total device has been

heated to its rated temperature level. However, with a fast rate of temperature rise, there is less

time for heat to penetrate to the inner element. The element therefore exerts less of an inhibiting

effect, so contact closure is obtained when the total device has been heated to a lower level. This,

in effect, compensates for thermal lag.

12.4.3 Rate-of-Rise Heat Detectors

These spot type detectors operate when the room temperature rises at a rate which exceeds a

predetermined value. For example, the effect of a flaming fire on the surrounding area is to rapidly

increase air temperature in the space. A fixed-temperature detector will not initiate an alarm until

the air temperature near the ceiling exceeds the design operating point. The rate-of-rise detector,

however, will function when the rate of temperature increase exceeds a predetermined value,

typically around 7 to 8 °C (12 to 15 °F) per minute. Rate-of-rise detectors are designed to

compensate for the normal changes in ambient temperature [less than 6.7 °C (12 °F) per minute]

that are expected under non-fire conditions.

12.4.4 Pneumatic Heat Detectors

In a pneumatic spot type heat detector, air heated in a tube or chamber expands, increasing the

pressure in the tube or chamber. This exerts a mechanical force on a diaphragm that close the

alarm contacts. If the tube or chamber were hermetically sealed, slow increases in ambient

temperature, a drop in the barometric pressure, or both, would cause the detector to initiate an

alarm regardless of the rate of temperature change. To overcome this, pneumatic detectors have

a small orifice to vent the higher pressure that builds up during slow increases in temperature or

during a drop in barometric pressure. The vents are sized so that when the temperature changes

rapidly, as in a fire, the rate of expansion exceeds the venting rate and pressure rises. When the

temperature rise exceeds 7 to 8 °C (12 to 15 °F) per minute, the pressure is converted to

mechanical action by a flexible diaphragm. Pneumatic heat detectors are available for both lineand spot-type detectors.
12-5

12.4.4.1 Line-Type Heat Detectors

The line-type consists of metal tubing, in a loop configuration, attached to the ceiling of the area to

be protected. Lines of the tubing are normally spaced not more than 9.1 m (30 ft) apart, not more

than 4.5 m (15 ft) from a wall, and with no more than 305 m (1,000 ft) of tubing on each circuit.

Also, a minimum of at least 5-percent of each tube circuit or 7.6 m (25 ft) of tube, whichever is

greater, must be in each protected area. Without this minimum amount of tubing exposed to a fire

condition, insufficient pressure would build up to achieve proper response.

In small areas where the line-type tube detector might have insufficient tubing exposed to generate

sufficient pressures to close the alarm contacts, air chambers or rosettes of tubing are often used.

These units act like a spot-type detector by providing the volume of air required to meet the

5-percent or 7.6 m (25 ft) requirement. Since a line-type rate-of-rise detector is an integrating

detector, it will actuate either when a rapid heat rise occurs in one area of exposed tubing, or when

a slightly less rapid heat rise takes place in several areas when tubing on the same loop is

exposed. The pneumatic principle is also used to close contacts within spot-type detector. The

difference between the line-and spot-type detectors is that the spot-type contains all of the air in

a single container rather than in a tube that extends from the detectors assembly to the protected

area(s).

12.4.5 Combination Heat Detectors

Many spot type heat detectors are available that utilize both the rate-rise and fixed-temperature

principles. The advantage of units such as these is that the rate-of-rise elements will respond

quickly to rapidly developing fires, while the fixed-temperature elements will respond to slowly

developing smoldering fires when design alarm temperature is reached. The most common

combination detector uses a vented air chamber and a flexible diaphragm for the rate-of-rise

function, while the fixed-temperature element is usually leaf-spring restrained by a eutectic metal.

When the fixed-temperature element reaches its design operating temperature, the eutectic metal

fuses and releases the spring, which closes the contacts.

12.4.6 Electronic Spot-Type Thermal Detectors

These detectors utilize a sensing element consisting of one or more thermistors, which produce a

change in electrical resistance in response to an increase in temperature. This resistance is

monitored by associated electronic circuitry, and the detector responds when the resistance

changes at an abnormal rate (rate-of-rise type) or when the resistance reaches a specific value

(fixed-temperature type).
12-6

12.5 Fixed-Temperature Heat Detector Activation

Fixed-temperature heat detectors are generally modeled by calculating the heat transfer from the

fire gases to the detector element, and the resultant temperature change. To simplify the

calculation, all current detector models treat the detector as a “lumped mass.” A lumped mass

model assumes that there are no temperature gradients within the detector element. This

assumption is reasonable for solder-type heat detectors, since the operating element has a low

mass. With bimetallic-type detectors, the lumped mass assumption may introduce some error,

since heat must be transferred to two slightly different parts.

Analytical methods for calculating detector temperature require that equations for temperature and

velocity of fire gases as a function of time must be inserted into the basic heat transfer equation.

The resulting differential equation must be integrated to arrive at an analytical solution to the heat

transfer equation.

For steady-state fires, the time required to heat the sensing element of a suppression device from

room temperature to operation temperature is given by (Budnick, Evans, and Nelson, 1997):

 (12-1)

Where:

activation t = sprinkler head activation time (sec)

RTI = Response Time Index (m-sec)1⁄2

ujet = ceiling jet velocity (m/sec)

Tjet = ceiling jet temperature (°C)

Ta = ambient air temperature (°C)

Tactivation= activation temperature of detector (°C)

The RTI concept was developed by Factory Mutual Research Corporation (FMRC) to be a

fundamental measure of thermal detector sensitivity. A detector’s RTI is determined in plunge tests

with a uniform gas flow of constant temperature and velocity and can be used to predict the

detector’s activation time in any fire environment. The RTI was developed under the assumption

that conductive heat exchange between the sensing element and supportive parts is negligible.

The RTI is a function of the time constant, , of the detector, which is related to the mass and

surface area of the detector element. Faster detectors have low response time indices and smaller

time constants. Detector elements with low time constants have low ratios of mass to surface area.

The RTI is defined by the following equation:

 (12-2)

Where:

me = mass of element (kg)

p(e) c = specific heat of element (kJ/kg-K)

he = convective heat transfer coefficient (kW/m -K) 2

Ae = surface area of element (m )

2

ujet = velocity of gas moving past the detector (m/sec)
12-7

The flow of heat and ceiling jet into a heat detector sensing element is not instantaneous; it occurs

over a period of time. A measure of the speed with which heat transfer occurs (the thermal

coefficient) is needed to accurately predict heat detector response. Called the detector time

0

constant ( ), this measure should be determined by a validated test (Heskestad, 1976). For a

gi even detector, the convective heat transfer coefficient (h ) and are approximately proportional to

the square root of the velocity (u) of the gases passing the detector. This relationship can be

expressed as the characteristic response time index, RTI, for a given detector:

 (12-3)

Where:

RTI = response time index (m-sec)1⁄2

0

 = detector time constant (sec)

u0 = gas velocity (m/sec)

The 0 0 detector time constant, , is measured in the laboratory at some reference velocity, u .

This expression can be used to determine the detector’s RTI.

UL-listed detector spacing can be used as a measure of detector sensitivity. Heskestad and

De 0lichatsios (1977), analyzed UL test data and calculated the time constant, , for various

combinations of UL-listed spacing and detector-operated temperature. The Subcommittee of NFPA

72 expanded that table to include a larger selection of detectors. The table is reproduced here as

Table 12-1.

Table 12-1. Time Constant of Any Listed Detector

Listed

Spacing

(ft)

Underwriter’s Laboratories, Inc. (UL)

Temperature Rating (°F)

FMRC

(All Temperatures)

128 135 145 160 170 196

De 0tector Time Constant, (sec)

10 400 330 262 195 160 97 196

15 250 190 156 110 89 45 110

20 165 135 105 70 52 17 70

25 124 100 78 48 32 - 48

30 95 80 61 36 22 - 36

40 71 57 41 18 - - -

50 59 44 30 - - - -

70 36 24 9 - - - -

Note: These time constants are based on an analysis of the UL and FMRC listing test procedures.

This table is reproduced from NFPA 72, Appendix B, 1999 Edition.
12-8

The time constants listed in Table 12-1 are based on a reference velocity of 1.5 m/sec (5 ft/sec).

These time constants can be converted to RTI values be using Equation 12-4, as follows:

 (12-4)

Tab 0le 12-2 provides the calculated values of RTI based on the detector time constant ( ) in Table 12-1.

Table 12-2. Detector Response Time Index of Any Listed Detector

Listed

Spacing

(ft)

Underwriter’s Laboratories, Inc. (UL)

Temperature Rating (°F)

FMRC

(All Temperatures)

128 135 145 160 170 196

Detector RTI (m-sec)1⁄2

10 490 404 321 239 196 119 240

15 306 233 191 135 109 55 135

20 325 165 129 86 64 21 86

25 152 123 96 59 39 - 59

30 116 98 75 44 27 - 44

40 87 70 50 22 - - -

50 72 54 37 - - - -

70 44 29 11 - - - -

The expressions for estimating the maximum ceiling jet temperature and velocity as a function of

ceiling height, radial position, and HRR were developed from an analysis of experiments with largescale fires having HRRs from 668 kW to 98,000 kW. The expressions are given for two regions—

one where the plume directly strikes the ceiling and the other, outside the plume region where a

true horizontal flow exists.
12-9

The ceiling jet temperature and velocity correlations of a fire plume are given by the following

expression:

 (12-5)

 (12-6)

 (12-7)

 (12-8)

Where:

Tjet = ceiling jet temperature (°C)

Ta = ambient air temperature (°C)

= heat release rate of the fire (kW)

H = distance from the top of the fuel package to the ceiling level (m)

r = radial distance from the plume centerline to the detector (m)

ujet = ceiling jet velocity (m/sec)

The above correlations are used extensively to calculate the maximum temperature and velocity

in the ceiling jet at any distance, r, from the fire axis. Note that the regions for which each

expression is valid are given as a function of the ratio of the radial position, r, to the ceiling height,

H. Moving away from the centerline of the plume jet, r/H increases. So, for example, for regions

where r/H>0.18, Equation 12-6 should be used. Based on the cases where the hot gases have

begun to spread under a ceiling located above the fire, Equation 12-5 applies for a small radial

distance, r, from the impingement point (see Figure 12-1).

Figure 12-1 Ceiling Jet Flow Beneath and Unconfined Ceiling Showing a Heat Detector
12-10

As w jet ith the temperatures velocities in the ceiling jet flow, u , there are two regions under a ceiling,

including (1) one close to the impingement point where velocities are nearly constant and

(2) another farther away where velocities vary with radial position.

The ceiling jet temperature is important in fire safety because it is generally the region where

sprinklers are located; therefore, knowledge of the temperature and velocity of the ceiling jet as a

function of position enables us to estimate the detector response time. The temperature and

velocity of a ceiling jet varies with the depth of the jet. Moving away from the ceiling, the

temperature increases to a maximum, then decreases closer to the edge of the jet. This profile is

not symmetric as it is with a plume, where the maximum occurs along the plume centerline. With

the knowledge of plume ceiling jet temperature and velocity, we can estimate the actuation time of

a fixed-temperature if we also know the spacing and the speed or thermal inertia of the detector.

The response of a fixed-temperature heat detector is given by its RTI.

12.6 Assumptions and Limitations

The method discussed in this chapter is subject to several assumptions and limitations:

(1) The plume ceiling jet correlations of temperature and velocity assume that the fire source

is located away from walls and corners. The primary impact of walls and corners is to

reduce the amount of entrained air into the plume. This has the effect of lengthening flames

and causing the temperature in a plume to be higher at a given elevation than it would be

in the open.

(2) The correlations for estimating the maximum ceiling jet temperature and velocity were

developed for steady-state fires and plumes under unconfined ceiling (where the smoke

layer does not develop below the ceiling jet during the time of interest).

(3) The plume ceiling jet correlations are valid for unconfined flat ceilings, as the environments

outside the ceiling jet are uniform in temperature and are atmospheric ambient. Caution

should be exercised with this method when the ceiling has an irregular surface such as

beam pockets.

(4) The correlations for estimating the maximum ceiling jet temperature and velocity were

developed for steady-state fires and plumes under unconfined ceiling (where the smoke

layer does not develop below the ceiling jet during the time of interest).

(5) The plume ceiling jet correlations are valid for unconfined ceilings, as the environments

outside the ceiling jet are uniform in temperature and are atmospheric ambient.

(6) All calculations for determining time to operation only consider the convective heating of

sensing elements by the hot fire gases. They do not explicitly account for any direct heating

by radiation from the flames.

(7) Caution should be exercised with this method when the overhead area is highly obstructed.

(8) The detectors are located at or very near to the ceiling. Very near to the ceiling would

include code compliant detectors mounted on the bottom flange of structural steel beams.

These methods are not applicable to detectors mounted well below the ceiling in free air.
12-11

12.7 Required Input for Spreadsheet Calculations

The user must obtain the following information before using the spreadsheet:

(1) heat release rate of the fire (kW)

(2) listed spacing of detectors (ft)

(3) activation temperature of detectors (°F)

(4) height to ceiling (ft)

(5) ambient room temperature (°F)

12.8 Cautions

(1) Use (10_Detector_Activation_Time.xls) and select “FTHDetector” spreadsheet

on the CD-ROM for calculations.

(2) Make sure all inputs are recorded in the correct units.

12.9 Summary

This chapter discusses a method of calculating the response time of heat detectors under

unobstructed ceilings in response to steady-state fires without forced ventilation.
12-12

12.10 References

Budnick, E.K., D.D. Evans, and H.E. Nelson, “Simplified Fire Growth Calculations” Section 11,

Chapter 10, NFPA Fire Protection Handbook, 18 Edition, A.E. Cote, Editor-in-Chief, National Fire th

Protection Association, Quincy, Massachusetts, 1997.

Heskestad, G., and H.F. Smith, “Investigation of a New Sprinkler Sensitivity Approval Test:

The Plunge Test,” FMRC Serial No. 22485, Factory Mutual Research Corporation, Norwood,

Massachusetts, December 1976.

Heskestad, G., and M.A. Delichatsios, “Environments of Fire Detectors—Phase 1: Effects of Fire

Size, Ceiling Height and Material,” Measurements Volume I, NBS-GCR-77-86, Analysis Volume II,

NBS-GCR-77-95, National Bureau of Standards, Washington, DC, 1977.

NFPA 72, National Fire Alarm Code , 1999 Edition, Appendix B: Engineering Guide for Automatic ®

Fire Detection Spacing, National Fire Protection Association, Quincy, Massachusetts.

12.11 Additional Readings

Alpert, R.L., “Calculation of Response Time of Ceiling-Mounted Fire Detectors,” Fire Technology,

Volume 8, pp. 181–195, 1972.

Alpert, R.L., and E.J. Ward, “Evaluation of Unsprinklered Fire Hazard,” Fire Safety Journal, Volume 7,

No. 177, 1984.

Bryan, J.L., Fire Suppression and Detection Systems, Macmillan Publishing, New York, 1993.

Evans, D.A., “Ceiling,” Sec. 2, Ch. 4, SFPE Handbook of Fire Protection Engineering, 2 Ed.,

nd

P.J. DiNenno, Editor-in-Chief, National Fire Protection Assoc., Quincy, Massachusetts, 1995.

Moore, W.D., “Automatic Fire Detectors” Sec. 5, Ch. 2, NFPA Fire Protection Handbook, 18 Ed.,

th

A.E. Cote, Editor-in-Chief, National Fire Protection Assoc., Quincy, Massachusetts, 1997.

Schifiliti, R.P., B.J. Meacham, and R.P. Custer, Chapter 1, Section 4, “Design of Detection

Systems,” SFPE Handbook of Fire Protection Engineering, 2 Edition, P.J. DiNenno, Editor-in- nd

Chief, National Fire Protection Association, Quincy, Massachusetts, 1995.
12-13

Example Problem 12-1: Fire Scenario with Heat Detectors

12.12 Problems

Example Problem 12.12-1

Problem Statement

A 34.5-ft (3.20-m ) lube oil pool fire with = 5,750 kW occurs in a space protected with fixed- 2 2

temperature heat detectors. Calculate the activation time for the fixed-temperature heat detectors,

using 10-ft (3.05-m) spacing, in an area with a ceiling height of 10 ft (3.05 m). The detector

activation temperature is 128 °F (53 °C), the radial distance to the detector is 4 ft (1.22 m), and the

ambient temperature is 77 °F (25 °C).

Solution

Purpose:

(1) Determine the response time of the fixed-temperature heat detectors for the fire

scenario.

Assumptions:

(1) The fire is located away from walls and corners.

(2) The fire is steady state and plume is under unconfined ceiling.

(3) Only convective heat transfer from the hot fire gases is considered.

(4) There is no heavily obstructed overhead.
12-14

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 10_Detector_Activation_Time.xls (click on FTHDetector)

FDT Input Parameters: s

-Heat Release Rate of the Fire = 5,750 kW

-Radial Distance to the Detector (r) = 4 ft

activation -Activation Temperature of the Fixed-Temperature Heat Detector (T ) = 128 °F

-Distance from the Top of the Fuel Package to the Ceiling (H) = 10 ft

a

-Ambient Air Temperature (T ) = 77 °F

activation -Click on the option button (u) for FTH detectors with T = 128 °F

-Select Detector Spacing: 10

Results*

Detector Type Heat Detector Activation

T activation ime (t )

(min.)

FixedTemperature0.27

*see spreadsheet on next page
12-15

Spreadsheet Calculations

FDT : 10_Detector_Activation_Time.xls (FTHDetector) s

CHAPTER 12. ESTIMATING HEAT DETECTOR RESPONSE TIME 

Version 19l5.0 

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INPUT PARAMETERS 

~atR&.<m Ra' OTU& File (J) IP'<t:I tl~) 

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H& tJUOTC&ItlagabW& Tct) OT fl& I (H) 

.:..mbl! •t.:..l TW1 ~ 1atm (r,) 

r/H= O.JO 

INPUT DATA FOR ESTIMATING HEAT OETECTO R RESPONSE TIME 

Activation 

Temperature T ~ w, - T• 128 F 

Q T= 135 F I 

f;tT= 145 F 

Ul U~ p<dg 

I It,~ 

10 

IS 

20 

2S 

30 

•o 

so 

70 

UHISI:*Cift:d Va iU 

Ul U~d p<dg 

l l..'ltl 

10 

IS 

20 

" 30 

•o 

so 

70 

4~ I:* ift: ._ ~ 

Ul U~ p<dg 

H'lt: 

10 

IS 

20 

" 30 

•o 

so 

70 

UH ISI=*Cift:d Va iU 

p,~;po u~ nn~ lul?x :...CUJ<11JH 

RTI ll~~ ¢.1 .. n1n o~ t111~ l'Fl .. o 128 

,. 128 

32S 128 

152 128 

... 128 

., 128 

72 128 

" 128 E•' ~ E•~l l' ~ 

P,~;po u~ TliH lUI? X .'.CUJa1JH 

RTI ~~ ¢.1 '-i n•np~ t111~ CF) 

... 13S 

233 13S 

loS 13S 

123 13S 

re 13S 

70 13S 

Sl 13S 

"' 13S 

E•' ~ E•~l l' ~ 

p,~;po u~ nn~ lul?x :...cu;aUH 

RTI ll~~ ¢.1 .. n1n o~ t111~ l'Fl 

"' u s 

'" u s 129 u s 

., u s 

7S u s 

., u s 

31 u s 11 u s 

E•' ~ E•~' l' ~ 

57 !0 fJO t! N 

4.00 11 

us., 3 21.00 ' 

10.00 11 

68.00 "I 

0 .70 

Calculate I 

Select Detector ~ 

(: '9 • Scrdl to d$•lr$d ' P 

acirg 

u 1ng 1ll$n 

Oick on •&IH 1on 

Select Detector Sp acirg 

Scrdl to d& llr$d ' P u 1ng 1ll$n 

Oick on •&IH 1on 

Select Detector Sp acirg 

Scrdl to CJ$•Ir$d ' P u 1ng 1ll$n 

Oick on •&IH 1on 

·~hi 
12-16

flT= 160 F I Ul Usred Spacing Response Time Index ktiv.Jtion 

r(ft) RTI(m-sec)· :r Temperature ('F) 

10 239 160 

15 135 160 

20 86 160 

25 59 160 

30 44 160 

40 22 160 

User Soeciie d \l.ilu e Enter\lalue Enter \l.ilue 

HoF I Ul Ust»ld Spacing Response Time Index .Activ.rtion 

r(ft) RTI(m-sec) i T emoer.Jture ('f) 

10 196 170 

15 109 170 

20 64 170 

25 39 170 

30 27 170 

User Soeciied \l.ilue Enter\lalue Enter \l.ilue 

e T= 196 F 

Ul Usred Spacing Response Time Index .Activ.rtion 

r(ft) RTI(m-sec) i Temperature ('F) 

10 119 196 

15 55 196 

20 21 196 

User Speciie d \l.ilu e Enter Value Enter \l.ilue 

~~ -. rr:~: NFPA.St.m.e:nd7Z, ,\';tr:.:>r.:h' ~ ,t...•:um ~~. A"'\'1HdxB. 7.m~ ~ 3 ::.0. 1. 191111, SO't:.:on. 

E STIMA TIIIG FIXED TE lvi'E RA JURE HEAT DETECTOR RESPOIISE Tllvl: R~ ·h~rr:~: FPA.F ~P «~"Tbr.H:trd>eo.'\ , 19M adl'br~ :l.'\)l. !"~ :t- -:«1. 

t.-..'·"''"' = ( RTV(w1,.,(1n (T1,. • T,.)"(T ,., • T ,.~...,.,, ) 

mere t,,,....,.,n = detectoracthmion lime (sec) 

RTI = detector response lime index (m-sec ). :~ 

u,., = ceiling jet ttelocity(ml.sec) 

T1

,. =ceiling jet temper.Jture (•C) 

T" = ambient air ltlmperature (•C) 

T.,.,,·""'" = activ.Jiion temper.Jture of detector ("C) 

Ceiling Jet Temperah.re calculation 

T ,., · T, = 16.g (O} 'I.+fn 

T ,., • T, = 5.38 (0./rf ":I/H 

mere T1 .. =ceiling jet tempel'3ture (•C) 

T, = ambie M air Wmperature (•C) 

torr .+I= 0.18 

torr .+I> 0.18 

~ =convective ponion ofthe heat release 1'3te (kVll) 

H =height of ceiling abot@ top of fuel (m) 

r= radial distance from the plume cemertine ro the detector(m) 

Ccnvective Heat Release Rate CalcUaticn 

,. =1 0 

mere 

a. = 

~ . cont@ctit@ heat release 1'3te (kVll) 

0 =heat release me ofthe h (kVll) 

1 .. = convectit@ heat release fraction 

<1025 kW 

Select Detector Spacing 

Scroll to ~sired spacirg then 

C I i ck on selection 

Select Detector Spacing 

Scroll to desired spacirg then 

C I i ck on selection 

Select Detector Spacing 

Scroll to ~sired spacirg then 

C I i ck on selection 
12-17

Radal Distarce to Ceiling Heigtt Ratio calculation 

r/H = 0.40 r/H > 0.15 

>0.15 

T,., . T., = 

T,., . T., = 

T,.,= 

39135 

538 ((O<*r213)1H 

39135 

411 35 ("C) 

Ceiling Jet Velocity Calculation 

<0.15 

u1,. = o.g6 (0.+1)'" torr .+I= 0.15 

u1

,. = (0.1g5 o·,.:. !lo" forr.+l > 0.15 

VlJhere u,., = ceiling jet \@locity(mJsec) 

0 =heat release me ofthe h (kVll) 

H =height of ceiling abo\@ 10p of fuel (m) 

r = radial distance from the plume centertine 10 the d ~ctor (m) 

Radal Oistarce to Ceiling Heigtt Ratio calculation 

r/H = 0 AO r/H > 0.15 

u1,. = (0.1g5 0"1.0 H"1/2)t"(5/6) 

u1,. = 5.171 mJsec 

Detector Activation Time CalcUaticn 

t,.,.,,,.,,., = ( RTV(w1.,)) On (T1,. • T,Y(T ,., • .,,,.,,.,, ) 

IIOTE: tft,,0 , .,.., ton = "11UM" Detector does n<lt M tivate 

667.38 

The abo\@ calco IRons are based on principles de \@loped in 1h e N F PA Fire Protection I-bn dbook 1g" 6:1ition, 

2003. Calcol31ions are based on certain assumptions and ha\@ inherent limimtions. 

The results of such calculations mayor may not have reasonable predictive capabilities for a gi\@n situation, 

and should only be interpre~d by an inimned user. 

Plthough each calcul31ion in 1he spreadsheet has been \@riied wilh 1he results of hand calcul31ion, 

there is no absolu~ guarantee ofthe accuracyofthese calcul31ions. 

#nyquestions, comments, concerns, and suggestions, or to report an error(s) in 1he spreadsheet, 

please send an email10 nxi@JlroQovormxs3@JlroQOV. 
12-18

Example Problem 12-2: Fire Scenario with heat detectors that

are equidistant from the fire source

Example Problem 12.12-2

Problem Statement

A trash fire with = 1,000 kW occurs in a space protected with fixed-temperature heat detectors.

Calculate the activation time for the fixed-temperature heat detectors, using 10 ft (3.05 m) spacing,

in an area with a ceiling height of 8 ft (2.43 m). The fire is located directly between heat detectors.

The detector activation temperature is 160 °F (71 °C), and the ambient temperature is 77 °F

(25 °C).

Solution

Purpose:

(1) Determine the response time of the fixed-temperature heat detectors for the fire

scenario.

Assumptions:

(1) The fire is located away from walls and corners.

(2) The fire is steady state and plume is under unconfined ceiling.

(3) Only convective heat transfer from the hot fire gases is considered.

(4) There is no heavily obstructed overhead.
12-19

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 10_Detector_Activation_Time.xls (click on FTHDetector)

FDT Input Parameters: s

-Heat Release Rate of the Fire = 1,000 kW

-Radial Distance to the Detector (r) = 5 ft

activation -Activation Temperature of the Fixed-Temperature Heat Detector (T ) = 160 °F

-Distance from the Top of the Fuel Package to the Ceiling (H) = 8 ft

a

-Ambient Air Temperature (T ) = 68 °F

activation -Click on the option button (u) for FTH detectors with T = 160 °F

-Select Detector Spacing: 10

Results*

Detector Type Heat Detector Activation

T activation ime (t )

(min.)

FixedTemperature1.34

*see spreadsheet on next page
12-20

Spreadsheet Calculations

FDT : 10_Detector_Activation_Time.xls (FTHDetector) s

CHAPTER 12. ESTIMATING HEAT DETECTOR RESPONSE TIME 

Version 19l5.0 

Th t!A' II gca• II.'I1) "Htlllab 'ft(~d'hl~latU~ hat<l!,cbl<tCUJa1JH 1J1H. 

Plll'\'llll ~tHt In YEllOWCEllS ar~ EnUr~d bj' Ul$ UtH . 

Pill'\'llll $t~n In GREEII CEllS llr$ AutomaUeall\' $$1&CUd trom tu DROP OOWII r.1EIIU for 1U O.Uctor H~d . 

. .:. 1 HbHq ~ ltOI1j>lttJa iH$ ate a• l 1.1t~d by1U pl~<ld hHaUII>aHd 01 tJ<IIH$ $p&Cirl?d 111U IIIHt 

p<II<IIIH' IL TU~ $pl?a<taHt 1$ pi ,~d <ti d $HU to <WJO.:I &II II ~ to a WDi g U 1Jy II a 0: ~~ . 

Th C ... ), 1111U IIUP,~ $ •o••:t b& IMd I=* TOle <U <11<11($1$ 1$ mad~. 

INPUT PARAMETERS 

~atR&.<m Ra' OTU& File (J) IP'<t:I tl~) 

Radl'll OttUO: b 1U &~ cb l (I) ''HtH IIJI I~ 1 <11 0 .707 11/2~ 011U ll>'d p<t r· 

.:..cu;a1m n111p& 1.'11111& oTU& Fk&d nmpe1a111 te H&atD&,ctol (r,..,,...., .. ~ 

&~ cb l Rupoue nne tutu {P.Tb 

H& tJUOTC&ItlagabW& Tct) OT fl& I (H) 

.:..mbl! lt.:..l TW1 ~ 1atm (r,) 

INPUT DATA FOR ESTIMATING HEAT OETECTO R RESPONSE TIME 

Activation 

Temperature T ~ w, - (QT• 128 F Ul U~d p<dg p,~;po u~ nn~ lul?x :...CUJ<11JH 

I It,~ RTI ll~~ ¢.1 .. n1no~ t111~ l'Fl 

10 .. o 128 

IS ,. 128 

20 32S 128 

2S 152 128 

30 ... 128 

•o ., 128 

so 72 128 

70 " 128 

UHISI:*Cift:d Va iU E•' ~ E•~l l' ~ 

Q T= 135 F I Ul U~d p<dg P,~ pou~ TllH lUI? X .'.CUJa1JH 

l l..'ltl RTI n~~ ¢.1 '-i n•np~ t111~ CF) 

10 ... 13S 

IS 233 13S 

20 ••s 13S 

2S 123 13S 

30 re 13S 

•o 70 13S 

so Sl 13S 

70 "' 13S 

~1 I:* ift:d ._ ~ E•' ~ E•~l l' ~ 

f;tT= 145 F Ul U~d p<dg p,~;po u~ nn~ lul?x :...cu;aUH 

H'lt: RTI ll~~ ¢.1 .. n1no~ t111~ l'Fl 

10 "' u s IS '" u s 20 129 u s 2S ., u s 30 7S u s 

•o ., u s 

so 31 u s 70 11 u s 

UH ISI=*Cift:d Va iU E•' ~ E•~l l' ~ 

1000.00 t! N 

5.00 11 

160 ., 

239.00 ' 

8.00 11 

68.00 "I 

0 .70 

Calculate I 

Select Detector Spacirg 

Scrdl to d$ •lr$d ' PUing 1ll$n 

Oick on •&IH1on 

Select Detector Spacirg 

Scrdl to d& llr$d ' PUing 1ll$n 

Oick on •&IH1on 

Select Detector Spacirg 

Scrdl to CJ$ •Ir$d ' PUing 1ll$n 

Oick on •&IH1on 

JSZ 111 

7 1.11 'C 
12-21

T=16o I Ul Usred Spacing Response Time Index ktiv.Jtion 

r(ft) RTI(m-sec)· :r Temperature ('F) 

10 239 160 

15 135 160 

20 86 160 

25 59 160 

30 44 160 

40 22 160 

User Soeciie d \l.ilu e Enter\lalue Enter \l.ilue 

HoF I Ul Ust»ld Spacing Response Time Index .Activ.rtion 

r(ft) RTI(m-sec) i T emoel'3lure ('f) 

10 196 170 

15 109 170 

20 64 170 

25 39 170 

30 27 170 

User Soeciied \l.ilue Enter\lalue Enter \l.ilue 

e T= 196 F 

Ul Usred Spacing Response Time Index .Activ.rtion 

r(ft) RTI(m-sec) i Temperature ('F) 

10 119 196 

15 55 196 

20 21 196 

User Speciie d \l.ilu e Enter Value Enter \l.ilue 

~~ -. rr:~: NFPA.St.m.e:nd7Z, ,\';tr:.:>r.:h' ~ ,t...•:um ~~. A"'\'1HdxB. 7.m~ ~ 3 ::.0. 1. 191111, SO't:.:on. 

E STIMA TIIIG FIXED TE lvi'E RA JURE HEAT DETECTOR RESPOIISE Tllvl: R~ ·h~rr:~: FPA.F ~P «~"Tbr.H:trd>eo.'\ , 19M adl'br~ :l.'\)l. !"~ :t- -:«1. 

t.-..'·"''"' = ( RTV(w1,.,(1n (T1,. • T,.)"(T ,., • T ,.~...,.,, ) 

mere t ..... ..-.. n = detectoracthmion lime (sec) 

RTI = detector response lime index (m-sec ). :~ 

u,., = ceiling jet ttelocity(ml.sec) 

T1 .. =ceiling jet temper.Jture (•C) 

T" = ambient air ltlmperature (•C) 

T""'·""'" = acthmlion temper.Jture of detector ("C) 

Ceiling Jet Temperah.re calculation 

T ,., · T" = 16.g (O} 'I.+fn 

T ,., • T" = 5.38 (0./rf -:t/H 

mere T1 .. =ceiling jet temper.Jture (•C) 

T" = ambient air ltlmperature (•C) 

torr.+!= 0.18 

torr.+!> 0.18 

~ =convective portion ofthe heat release r.Jte (kVll) 

H =height of ceiling abotte top of fuel (m) 

r= radial distance from the plume centertine ro the detector(m) 

Ccnvective Heat Release Rate CalcUaticn 

,. =1 0 

mere 

a. = 

~ . conttectitte heat release r.Jte (kVll) 

0 =heat release me ofthe h (kVll) 

1 .. = convectitte heat release fraction 

700 kW 

Select Detector S f acing 

acirgthen 

I •t 1. ,

Scroll to dlsired sp 

C I i ck on selection 

Select Detector S pacing 

Scroll to desired sp acirgthen 

C I i ck on selection 

Select Detector S pacing 

Scroll to desired sp acirgthen 

C I i ck on selection 
12-22

Radal Distarce to Ceiling Heigtt Ratio calculation 

r/H = 0.63 r/H > 0.15 

>0.15 

T,., . T., = 

T,., . T., = 

T,.,= 

13135 

538 ((OcA-r2/3)1H 

13135 

151 35 ("C) 

Ceiling Jet Velocity Calculation 

<0.15 

u1,. = o.g6 (0.+1)'" torr .+I= 0.15 

u1

,. = (0.1g5 o·,.:. !lo" forr.+l > 0.15 

VlJhere u,., = ceiling jet \@locity(mJsec) 

0 =heat release me ofthe h (kVll) 

H =height of ceiling abo\@ 10p of fuel (m) 

r = radial distance from the plume centertine 10 the d ~ctor (m) 

Radal Oistarce to Ceiling Heigtt Ratio calculation 

r/H = 0.63 r/H > 0.15 

u1,. = (0.1g5 0"1.0 H"1/2)t"(5/6) 

u1,. = 2.143 mJsec 

Detector Activation Time CalcUaticn 

t,.,.,,,.,,., = ( RTV(w1.,)) On (T1,. • T,Y(T ,., • .,,,.,,.,, ) 

IIOTE: tft,,0 , .,.., ton = "11UM" Detector does n<lt M tivate 

301.61 

The abo\@ calco IRons are based on principles de \@loped in 1h e N F PA Fire Protection I-bn dbook 1g" 6:1ition, 

2003. Calcol31ions are based on certain assumptions and ha\@ inherent limimtions. 

The results of such calculations mayor may not have reasonable predictive capabilities for a gi\@n situation, 

and should only be interpre~d by an inimned user. 

Plthough each calcul31ion in 1he spreadsheet has been \@riied wilh 1he results of hand calcul31ion, 

there is no absolu~ guarantee ofthe accuracyofthese calcul31ions. 

#nyquestions, comments, concerns, and suggestions, or to report an error(s) in 1he spreadsheet, 

please send an email10 nxi@JlroQovormxs3@JlroQOV. 
13-1

CHAPTER 13. PREDICTING COMPARTMENT FLASHOVER

13.1 Objectives

This chapter has the following objectives:

• Explain the incipient stage of a fire.

• Characterize flashover and its stages.

• Describe how to predict the HRR required for flashover and post-flashover temperature

in a compartment.

13.2 Introduction

Following ignition, a compartment fire experiences a slow growth period, which is often referred to

as the “incipient stage.” During this stage, all of the measurable fire parameters [heat release rate

(HRR), rate of fuel or oxygen consumption, and temperature of the compartment gases] are low and

increase at a low rate.

After the incipient stage, the fire begins to grow more rapidly, as in the parabolic fire growth curves

described by the t fires. (See Appendix B for details.) The HRR and rate of fuel/oxygen 2

consumption also increase rapidly. This acceleration, in turn, also increases the compartment gas

temperature. In an adequately ventilated compartment, the rate of air entering the compartment

also increases. At some point in the history of a given fire, the rate of fire growth increases so

rapidly that all combustibles in the compartment reach their ignition temperature and become

involved in the combustion process and “flashover” is achieved. Flashover is a complex topic and

a number of theories and calculation methods will be presented. Figure 13-1 illustrates of the postflashover compartment fire in which the fire is assumed to be volumetric rather than point source.

At the high temperatures that occur in the gas layer of a post-flashover fire, significant radiative heat

transfer occurs from the carbon dioxide gas, water vapor, and soot particles in the smoke. The gas

layer and flames radiate to the floor, walls and ceiling, back to the fire and fuel sources, to any other

objects that may be present in the compartment, and out through any openings in the enclosure.

In addition, the heated walls, ceiling, and other heated objects are re-radiating heat back within the

enclosure.

Often, a post-flashover fire may have significant fuel to continue burning, but the air entering the

room may be limited. The fire, which might otherwise continue to grow if it were burning in

unconfined space, enters a period where it is said to be “ventilation controlled,” meaning that the

fire ceases to grow because of a lack of oxygen. The rates of fuel consumption and heat release

stall, and the compartment temperature ceases to climb as rapidly it did before flashover. These

parameters may then begin to decrease slightly as a result of the less-than-stoichiometric air-fuel

mixture. The fire may continue to decay until the air supply ratio become stoichiometric or greater,

thereby allowing further fire growth. At this point, the fire may become “fuel-controlled,” meaning

the amount of available fuel (rather than the available air supply) dictates the rate of burning.
13-2

Figure 13-1 Flashover and Postflashover Compartment Fire

The fire may again grow to a ventilation controlled condition and continue in a transient state

alternate between ventilation and fuel control throughout the remaining active burning period of the

fire. It is during this post-flashover stage that the fire barrier system must function at its highest

efficiency to contain the fire. Eventually, the fire will enter its final fuel-controlled state as the fuel

is totally consumed and the fire decays to extinction.
13-3

Several physical processes may be described in order to characterize the event that is frequently

referred to as flashover. Fire fighters generally recognize flashover as the condition characterized

by emission of flames through the open doorway of a fire compartment. It is the transition from the

fire growth stage to the fully developed stage in the development of a compartment fire that is

stages demarcates pre-flashover and post-flashover. Flashover is the phenomenon that defines

the point of time at which all combustibles in the compartment are involved in the fire and flames

appear to fill the entire volume. Gas temperatures of 300 to 650 °C (572 to 1,202 °F) have been

associated with the onset of flashover, although temperatures of 500 to 600 °C (932 to 1,112 °F)

are more widely accepted.

The International Standards Organization (ISO), “Glossary of Fire Terms and Definitions” (ISO/CD

13943), defines “flashover” as “the rapid transition to a state of total surface involvement in a fire

of combustion material within an enclosure,” Flashover is the term given to the relatively abrupt

change from a localized fire to the complete involvement of all combustibles within a compartment.

Flashover is described by four fire stages. The hot buoyant plume develops during the first stage

following ignition, and then reaches the ceiling and spreads as a ceiling jet (second stage). During

the third and fourth stages, the hot layer expands and deepens, and flow through the opening is

established.

When a fire in a compartment is allowed to grow without intervention, temperatures in the hot upper

layer increase, thereby increasing radiant heat flux to all objects in the room. If a critical level of

heat flux is reached, all exposed combustible items in the room will begin to ignite and burn, leading

to a rapid increase in both heat release rate and temperatures. This transition is called “flashover”.

The fire is then referred to as “post-flashover fire,” a “fully developed fire,” or a fire that has reached

“full room involvement.”

The above descriptions of flashover are somewhat general. In order to more clearly define the

specific point at which flashover occurs, we must use some definite physical characteristics:

(1) Flashover is the time at which the temperature rise in the hot gas reaches 500 °C (932 °F).

[600 °C (1112 °F) is sometimes also used to define flashover].

(2) Flashover is the time at which the radiant heat flux density at the floor of the compartment

reaches a minimum value of 20 kW/m throughout. 2

(3) Flashover may be defined in terms of the rate of heat release ( ) from the fire in

T

comparison to the total area of the compartment enclosing surfaces (A ), the area of any

v v ventilation openings (A ), and the height of any ventilation openings (H ), is illustrated by the

following expression:

 (13-1)
13-4

The first definition, in terms of temperature of the ceiling layer, is based upon experimental

observation. Some compartment fire tests define the flashover point as the time at which flames

just begin to emerge through openings in the compartment. Examination of the empirical data from

testing has shown that the flame emergence point generally corresponds to a ceiling layer

temperature between 500 °C to 600 °F (932 °F to 1,112 °F).

The second definition of flashover is given in terms of heat flux at the floor of the compartment. In

essence, this definition describes the heat flux that would be necessary to establish simultaneous

ignition of most ordinary combustibles throughout the enclosure. A radiant heat flux density of 20

kW/m is sufficient for piloted ignition of most ordinary combustibles. In most cases, a ceiling layer 2

at 500 °C (932 °F) will radiate to the floor at a minimum rate of 20 kW/m in a typical compartment. 2

The third definition, which correlates HRR and compartment geometries, is more descriptive and

more useful for predicting the physical conditions that might be necessary to establish either of the

criteria required by the first two definitions. While researchers use different definitions for the onset

of flashover, they reach some level of agreement on the temperature and heat flux necessary for

the onset of flashover.

Hägglund, Jannson, and Onnermark (1974) experimentally observed flames exiting the doorway

when the gas temperature about 10 mm (0.40 in) below the ceiling reached 600 °C (1,112 °F).

Babrauskas (1977) applied this criterion to a series of 10 full-scale mattress fires; however, only 2

exhibited a potential to flashover the test compartment. These two mattress fires led to maximum

gas temperatures well in excess of 600 °C (1,112 °F), with flashover observed near that

temperature. In experiments conducted in a full-scale compartment at the National Bureau of

Standards (NBS), now the National Institute of Standards and Technology (NIST), Fang (1975)

reported an average upper room temperature ranging from 450 to 650 °C (842 to 1,202 °F)

provided sufficient a level of radiation transfer to result in the ignition of crumpled newspaper

indicators at floor level in the compartment. The average upper room gas temperature necessary

for spontaneous ignition of newsprint was 540 ± 40 °C (1,004 ± 104 °F). It should be noted that this

average included low temperatures at the mid-height of the compartment, and that temperatures

measured 25 mm (1 in.) below the ceiling in this test series usually exceeded 600 °C (1,112 °F).

Fang (1975) also found that strips of newspaper placed at floor level in room burn tests ignited by

fluxes of 17 to 25 kW/m , while 6.4 mm (1/4 in.) thick fir plywood ignited at 21 to 33 kW/m . Lee and

2 2

Breese (1979) reported average heat fluxes at floor level of 17 to 30 kW/m at flashover for full2

scale tests of submarine compartments.

The NFPA 555 “Guide on Methods for Evaluating Potential for Room Flashover,” (NFPA 555) define

as room flashover in terms of temperature rise and heat flux at floor level. According to the NFPA

guide, a gas temperature rise at flashover of 600 °C (1,112 °F) is a reasonable expectation, as is

heat flux 20 kW/m at floor level at flashover. 2
13-5

13.3 Compartment Flashover

Researchers have extensively studied the minimum HRR needed to cause flashover in a

compartment. The studies suggest that minimum rate increases with the size of the compartment

and depends, in a complex way, on the ventilation in the compartment. If there is too little

ventilation, flashover cannot occur. If there is an excessive amount of ventilation, the excess air

flow dilutes and cools the smoke, so a larger HRR is needed to reach the critical temperature

condition for flashover. The construction materials and thickness of the ceiling and upper walls are

also important factors in determining whether flashover will occur. These factors also determine

the time required for flashover in a compartment that does reach the critical temperature.

Researchers have used several approaches to estimate the onset of flashover within a

compartment. These approaches are typically based on simplified mass and energy balances in

a single-compartment fire along with correlations to fire experiments. Visually, researchers report

flashover as a discrete event in full-scale fire tests and actual fire incidents. Numerous variables

can affect the transition of a compartment fire to flashover. Thermal influences are clearly important

where radiative and convective heat flux are assumed to be driving forces. Ventilation conditions,

compartment volume, and chemistry of the hot gas layer can also influence the occurrence of

flashover. Rapid transition to flashover adds to the uncertainty of attempts to quantify the onset of

flashover with laboratory measurements.

Although the flashover process is not easy to quantify in terms of measurable physical parameters,

a working definition can be formulated from the considerable body of flashover-related full-scale

fire test data accumulated from a variety of sources.

13.3.1 Method of Predicting Compartment Flashover HRR

The occurrence of flashover within a compartment is the ultimate signal of untenable conditions

within the compartment of fire origin as well as a sign of greatly increased risk to other

compartments within the structure. A number of experimental studies of full-scale fire have been

performed provide simple correlations to predict HRR required for flashover.

13.3.1.1 Method of McCaffrey, Quintiere, and Harkleroad (MQH)

McCaffrey, Quintiere, and Harkleroad (1981) found that their data for predicting compartment hot

gas temperature may extend to predict the HRR required to result in flashover in the compartment

and obtained the following expression:

 (13-2)

Where:

= heat release rate to cause flashover (kW)

hk = effective heat transfer coefficient (kW/m -K) 2

AT = total area of the compartment enclosing surfaces (m ), excluding area of vent opening 2

Av = area of the ventilation openings (m )

2

hv = height of the ventilation openings (m)
13-6

13.3.1.2 Method of Babrauskas

Babrauskas (1980) developed a simplified relationship that represent values correlated to

experiments produce flashover. Based on the 33 compartment fire tests with HRR range from 11

to 3,840 kW with fuels primarily of wood and polyurethane, Babrauskas found that the HRR

required to cause flashover is describe by the following relation:

 (13-3)

Where:

= heat release rate to cause flashover (kW)

Av = area of the ventilation openings (m )

2

hv = height of the ventilation openings (m)

Equation 13-3 is an extremely simply and easy to use relation, though it does not take into account

the area and thermal properties of compartment enclosing surfaces.

13.3.1.3 Method of Thomas

Thomas (1981) (also reported by Walton and Thomas, 1995) developed a semi-empirical

calculation of the HRR required to cause flashover in a compartment. He presented a simple model

of flashover in a compartment, which he used to study the influence of wall-lining materials and

thermal feedback to the burning items. He predicted a temperature rise of 520 °C (968 °F) and a

black body radiation level of 22 kW/m to an ambient surface away from the neighborhood of 2

burning wood fuel at the predicted critical heat release rate necessary to cause flashover. Thomas’

flashover is the result of simplifications applied to an energy balance of a compartment fire.

The resulting correlation yields the minimum HRR for flashover:

 (13-4)

Where:

= heat release rate to cause flashover (kW)

AT = total area of the compartment enclosing surfaces (m ), excluding area of vent opening 2

Av = area of the ventilation openings (m )

2

hv = height of the ventilation openings (m)

The constants in Equation 13-4 represent values derived from experiments producing flashover.

This correlation assumes that conduction has become stationary. The thermal penetration time is

long for compartments with thick concrete walls, and it is unlikely that a fire slowly and gradually

grows up to in a number of hours. A reasonable time frame for estimating the likelihood of

flashover is in the range of a few minutes up to around 30 minutes. We note that firefighter reaction

time is usually also within this range (Karlsson and Quintiere, 1999).
We occasionally encounter temperatures in excess of 1300–1400 °C (2,372–2,552 °F), 1

which is sufficient to cause the surface of bricks to fuse (melt). For example, the Summit Rail

Tunnel Fire (Department of Transport, 1984) produced sufficiently high temperatures to cause

the faces of brick-lined ventilation shafts to fuse.

13-7

13.3.2 Method of Predicting Compartment Post-Flashover Temperature

After flashover has occurred, the exposed surfaces of all combustibles items in the compartment

will be burning and the HRR will developed to a maximum, producing high temperatures (see Figure 13-1).

Typically, this may be as high as 1,100 °C (2,012 °F), but much higher temperatures can be

obtained under certain conditions (Drysdale, 1998). These will be maintained until the rate of 1

generation of flammable volatile begins to decrease as a result of fuel consumption. It is during the

period of the fully developed fire that building elements may reach temperatures at which they may fail.

Thomas (1974) developed an approach to estimate peak compartment temperature based on postflashover enclosure fire data. Law (1978) extended this approach to include both natural and

forced ventilation through the evaluation of extensive pre-flashover compartment fire test data. The

results indicate that the predictions reasonably, but not exactly, predict the temperatures reported

in the test fires.

Drawing on data gathered in the Conseil Internationale du Batiment (CIB) Research Program of

fully developed compartment fires Thomas (1974) and Law (1978) found following correlation to

predict post-flashover compartment temperature with natural ventilation:

 (13-5)

 (13-6)

Where:

= heat release rate to cause flashover (kW)

 = ventilation factor

AT = total area of the compartment enclosing surfaces (m ), excluding area of vent opening 2

Av = area of the ventilation openings (m )

2

hv = height of the ventilation openings (m)

Note that Equation 13-5 does not consider variations in the thermophysical properties of

compartment enclosing surfaces.
13-8

13.4 Fire Severity

Fires burn with differing intensities and produce significant spatial variability in terms of severity.

The fundamental step in designing structures (fire barriers) for fire safety is to verify that the fire

resistance of the structure (or each part of the structure is greater than the severity of the fire to

which the structure is exposed. The verification requires that the following condition be satisfied:

Where fire resistance is measure of the ability of the structure to resist collapse, fire spread or other

failure during exposure to a fire of specified severity, and fire severity is a measure of the potential

destructive impact of the burnout of all the available fuel in a compartment (Buchanan, 2001) most

often it defined in terms of a period of exposure to the standard test fire.

Damage to a structure is largely dependent on the amount of heat absorbed by the structural

elements. Heat transfer from post-flashover fires is primarily radiative which is proportional to the

forth power of the absolute temperature. Hence, the severity of a fire is largely dependent on the

temperatures reached and the duration of the high temperatures.

13.4.1 Method of Margaret Law

Law (1974) developed a correlation to predict fire severity (duration) based on data developed

through an international research program. The fire severity correlation predicts the potential

impact of a pos-flashover fire in terms of equivalent exposure in a fire endurance furnace fired to

follow the European equivalent standard similar to ASTM E119 and NFPA 251.

The fire severity of available fuel load in a compartment with at least one opening can be estimated

from the following equation:

 (13-7)

Where:

f

t = fire severity or duration (sec)

K = correlational constant

Leq = total fire or fuel load in equivalent of wood (kg)

Av = area of ventilation opening (m )

2

AT= total area of the compartment enclosing boundaries excluding area of vent opening (m )

2
13-9

Total fire or fuel load in compartment equivalent of wood with a given mass if given by:

 (13-8)

Where:

Leq = total fire or fuel load in equivalent of wood (kg)

L = total fire or fuel load in compartment (kg)

Hc = effective heat of combustion (kJ/kg)

Hc, wood = wood heat of combustion (kJ/kg)

The compartment interior surface area can be calculated as follows:

AT c c = ceiling + floor 2 (w x l )

c c + 2 large walls 2 (h x w )

c c + 2 small walls 2 (h x l )

0

 - total area of vent opening(s) (A )

AT c c c c c c v = [2 (w x l ) + 2 (h x w ) + 2 (h x l )] - A (13-9)

Where:

AT = total compartment interior surface area (m ), excluding area of vent opening(s) 2

wc = compartment width (m)

c

l = compartment length (m)

hc = compartment height (m)

Av = total area of ventilation opening(s) (m )

2

The total area of ventilation opening is given by:

A =v v v w x h (13-10)

Where:

Av = total area of ventilation opening(s) (m )

2

wv = vent width (m)

hv = vent height (m)
13-10

13.5 Assumptions and Limitations

The methods discussed in this chapter are subject to several assumptions and limitations:

(1) The correlations were developed from a simplified mass and energy balance on a single

compartment with ventilation openings.

(2) The experimental data used to develop the correlation included compartments with

thermally thick walls and fires of wood cribs. Typically, heat transfer through compartment

surfaces is accounted for with a semi-infinite solid approximation.

(3) The fire severity correlation is not appropriate for compartment that do not have openings

for ventilation. While no precise minimum can be stated, it is suggested that this method

not be used unless the size of the opening is at least 0.4 m (4 ft ). 2 2

13.6 Required Input for Spreadsheet Calculations

The user must obtain the following information before using the spreadsheet:

(1) compartment width (ft)

(2) compartment length (ft)

(3) compartment height (ft)

(4) vent width (ft)

(5) vent height (ft)

13.7 Cautions

(1) Use spreadsheet (13_Compartment_ Flashover_Calculations.xls) on the CD-ROM

for calculations.

(2) Make sure input parameters are recorded in the correct units.

13.8 Summary

Flashover is a complex topic. Determination of temperatures associated with compartment fires

provides a means of assessing the likelihood of the occurrence of flashover. Danger of flashover

is assumed to occur if the analysis indicates a smoke layer temperature in excess of 450 °C

(842 °F). Typically, flashover occurs when the smoke layer temperature reaches between 500 °C

(932 °F) and 600 °F (1,112 °F). Hot smoke layers are considered to be close to black body

radiators. At 450 °C (842 °F) the radiation from the smoke would be approximately 15 kW/m2

(1.32 Btu/ft -sec). Temperatures above the 450 °C (842 °F) level generate a higher incident heat 2

flux on the burning fuel in a compartment than if the fire were in the open.
13-11

13.9 References

ASTM E 119 - 98, “Standard Test Methods for Fire Tests of Building Construction and Materials,”

ASTM Fire Test Standard, Fifth Edition, American Society of Testing and Materials,

West Conshohocken, Pennsylvania, 1999, pp. 793-813.

Babrauskas, V., “Combustion of Mattresses Exposed to Flaming Ignition Sources,” Part I, Full-scale

Tests and Hazard Analysis, NBSIR-1290, National Bureau of Standards, Washington, DC, 1977.

Babrauskas, V., “Estimating Room Flashover Potential,” Fire Technology, Volume 16, No. 2,

pp. 95–103, May 1980.

Budnick, E.K., D.D. Evans, and H.E. Nelson, “Simplified Fire Growth Calculations” Section 3,

Chapter 9, NFPA Fire Protection Handbook, 19 Edition, A.E. Cote, Editor-in-Chief, National Fire th

Protection Association, Quincy, Massachusetts, 2003.

Department of Transport, “Report on the Derailment and Fire that Occurred on 20 December 1984 th

at Summit Tunnel in the London Midland Region of British Railways,” Her Majesty’s Stationery

Office (HMSO), London, 1984.

Drysdale, D.D., Chapter 10, “The Post-Flashover Compartment Fire,” An Introduction to Fire

Dynamics, 2 Edition, John Wiley and Sons, New York, pp. 146–149, 1998. nd

Fang, J.B., “Fire Buildup in a Room and the Role of Interior Finish Materials,” Technical Report 879,

National Bureau of Standards (NBS), Washington, DC, 1975.

Hägglund, B., R. Jannson, & B. Onnermark, “Fire Development in Residential Rooms After Ignition

from Nuclear Explosion,” FAO C20016-DG (A3), Forsvarets, Forskningsanstalt, Stockholm, 1974.

ISO/CD 13943, “Glossary of Fire Terms and Definitions,” International Standards Organization,

Geneva, 1996.

Karlsson, B., and J.G. Quintiere, Enclosure Fire Dynamics, Chapter 6, “Gas Temperature in

Ventilated Enclosure Fires,” CRC Press LLC, New York, pp. 115–140, 1999.

Law, M., “Fire Safety of External Building Elements—The Design Approach,” AISC Engineering

Journal, Second Quarter, American Institute of Steel Construction (AISC), 1978.

Law, M., “Prediction of Fire Resistance,” Paper No. 2 of Symposium No. 5, Fire Resistance

Requirements of Buildings–A New Approach, September 28, 1971, Department of the Environment

and Fire Offices’ Committee Joint Fire Research Organization, HMSO, UK.

Lee, B. T., and J.N. Breese, “Submarine Compartment Fire Study — Fire Performance Evaluation

of Hull Insulation,” NBSIR-78-1584, National Bureau of Standards (NBS), Washington, DC, 1979.

McCaffrey, B.J., J.G. Quintiere, and M.F. Harkleroad, “Estimating Room Temperature and

Likelihood of Flashover Using Fire Test Data Correlation,” Fire Technology, Volume 17, No. 2,

pp. 98–119, 1981.
13-12

NFPA 251, “Standard Methods of Tests of Fire Endurance of Building Construction and Materials,”

1999 Edition, National Fire Protection Association, Quincy, Massachusetts.

NFPA 555, “Guide on Methods for Evaluating Potential for Room Flashover,” 2000 Edition,

National Fire Protection Association, Quincy, Massachusetts.

Thomas, P.H., “Testing Products and Materials for their Contribution to Flashover in Rooms,”

Fire and Materials, Volume 5, Number 3, pp. 130–111, September 1981.

Thomas, P.H., “Fire in Model Rooms, Conseil Internationale du Batiment (CIB) Research Program,

Building Research Establishment, Borehamwood, Hertfordshire, England, 1974.

Walton, W.D., and P.H. Thomas, “Estimating Temperatures in Compartment Fires,” Section 3,

Chapter 3-6, SFPE Handbook of Fire Protection Engineering, 2 Edition, P.J. DiNenno, Editor-in- nd

Chief, National Fire Protection Association, Quincy, Massachusetts, 1995.
13-13

13.10 Problems

Example Problem 13.10-1

Problem Statement

Consider c c c a compartment 20 ft wide x 25 ft long x 12 ft high (w x l x h ), with an opening 3 ft wide

and v v 8 ft high (w x h ). The interior lining material of the compartment is 6 in. concrete. Calculate

PFO the HRR necessary for flashover, , and the post-flashover compartment temperature, T .

Solution

Purpose:

(1) Determine the heat release rate for flashover for the given compartment.

Assumptions:

(1) Natural Ventilation

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 13_Compartment_Flashover_Calculations.xls

(click on Post_Flashover_Temperature to calculate the post-flashover temperature)

(click on Flashover-HRR to calculate the HRR for flashover)

FDT Input Parameters: s

c

-Compartment Width (w ) = 20 ft

c

-Compartment Length (l ) = 25 ft

c

-Compartment Height (h ) = 12 ft

v

-Vent Width (w ) = 3 ft

v

-Vent Height (h ) = 8 ft

-Interior Lining Thickness (*) = 6 in. (Flashover-HRR only)

-Select Material: Concrete (Flashover-HRR only)

Results*

Post-Flashover Compartment

Tempe PFO rature (T )

°C (°F)

HRR for Flashover

(kW)

Method of Law Method

of MQH

Method of

Brabauskas

Method of

Thomas

811 (1,492) 1,612 2,611 2,806

 *see spreadsheet on next page
13-14

Spreadsheet Calculations

(a) FDT : 13_Compartment_Flashover_Calculations.xls (Post_Flashover_Temperature) s

CHAPTER 13. PREDICTING COMPARTMENT POST-FLASHOVER 

TEMPERATURE 

Vet·sion 1805.0 

The following calculations estimate the compartment post-flashover ~mper ature. 

Para mel a-s in YELL OW CELLS are Enta-ed by the User. 

All subsequent output values are calculated by the spreadsheet and based on values specified in the input 

parameters. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a cel(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

COMPARTMENT INFORMATION 

Compartment Width (IA0 

Compartment Length (l:) 

Compartment Height(h:) 

Vent Width (WJ) 

Vent Height (ht~) 

20.00 

25.00 

12.00 

3.00 

8.00 

Calculate 

PREDICTING COMPARTMENT POST .fLASHOVER TEMPERATURE 

METHOD OF MARGARET LAW R~'lf I? •o: :s ,:PE ,"'{;?,; cb\l«i ~ ne- Pro:r.>o;t\lfi t: t.""'r,•~G J " 5:f t~\'f. 2002, Pi?'if~ $3. 

TPFO{Jo\~ =6000(1 • e<l.l!")/(vO) 

• 

• 

• 

• 

• 

Where TPFO (JJ'o~ = m~imum compartment post-flashover temperature (•C) 

0= ventilation factor 

Where 0= (AT· A,) I A, (vh,) 

0.0~ .... 

7 .G2 m 

3.6576 .... 

0.9 14 Ill 

2.433 Ill 

AT= total area of the compartment enclosing surface boundaries excluding area of vent openings (ml 

A') = area ofventilation opening (m) 

h'-' =height of ventilation opening (m) 

Area of Ve-Jtilation OpeninA Calc:ulction "'= (w,) (h,) 

Where 

A,= 

~=area ofventilation opening (m) 

WJ= ventwidth(m) 

ht< =vent height (m) 

223 m.: 

Area of Compartment Enclosing Surface Boundaries 

AT= [2(1AA:X l:)+ 2(h.:x~AA:)+2(h x l:))· A J 

Where AT= total area of the compartment enclosing surface boundaries excluding area of vent openings (m") 

w.: = compartmentwidth (m) 

1: = compartment length (m) 

he= compartment height(m) 

A') = area ofventilation opening (m) 

19101 m'" 
13-15

Ventilation Factor Calculation 

0= (AT· A,)/ A,(vh,) 

Where 0= ventilation factor 

AT= total area of the compartment enclosing surface boundaries excluding area of vent openings (ml 

A') = area ofventilation opening (m) 

h'-' =vent height (m) 

5422 m·• ~ 

Compartment Post-Flashover Terrpercture Calculation 

TPFO {Ill = 6000 (1 • e" ·':) /(vO) 

The above calculations are based on principles developed in the SFPE Handbod< of Fire 

Pro~ction Engineering, 3

14 Edition, 2002. 

Calculations are based on certain assumptions and have inherent limitations. The results of 

such calculations may or may not have reasonable predictive capabilities for a given situation, 

and should only be in~rpreted by an informed user. 

AHhough each calculation in the spreadsheet has been veri1ied with the results of hand 

calculation, there is no absolute guarantee of the accuracy of these calculations. 

ArPJ questions, comments. concerns. and suggestions, or to report an error(s) in the 

spreadsheets. please send an email to rod@nrc.gov or mxs3@nrc.gov. 
13-16

(b) FDT : 13_Compartment_Flashover_Calculations.xls (Flashover_HRR) s

CHAPTER 13. PREDICTING COMPARTMENTFLASHOVER HEAT RELEASE RATE 

Version 1805.0 

Th fOI.)Wiig ca• 'IO,_ $ 1Jil a' 1U Ill" .... Ull hat I~ <16~ 1<1, I~ IUI ~d to Q;llllp<t11111Ut 'IL. O!J~I. 

Pllrlllfl$,ri iO YEllOWCEllS ilr$ Ent~nd bj' UU Uur. 

Pllrlllfl $'rl In G REEII CEllS ilr$ AUtolflll11CIIIIJ' h iHUd fi'OIQ 1U DROP OOVVII f.1E IIU for 1ll$ t.1 ~ter l h iHUd . 

. :. II :<$ ~q iUt I1j lt lt U al~ cat:l 1.1t~d by ~ pl~<ld$ •Htaul b.'IHd o • tJ<tltH p~ ifl?d II ~ " Pit 

p<n<llll$' " · n t ' P'""' ' ' Ht ~ p1W.c'd aut • 1e b atio•:t eno" dH b a w1019 e 11J>{ 11 a o: tl(') . 

Th c•aptH IIIU IIUREG $. 0Hibe teadl=*fOie <U <U<tlf$1$ ~ ma\le. 

COIII \.'U111 UtV"V.:IQ ;, ~ 

COIIIP,'II111 Ut '* l gt• (I;) 

COIIIP,'U111 ut HH;JU (• c) 

VutV">H:IU ;;.N0 

w ltH e•;~ •t ~ 

''''bl lllllg TU:tae" @) 

"' lbllllllg Th Dll<tiCOid i CUJit{ ;J:) 

THERMAL PROP ERTlE$ OATA 

l.latHI.'II Th hi a iCOUIICUJit{ 

I; f;V\1/hl-1\i 

.0:..1111'1 , ...... ll ) 0 2 00 

StH I ,PS~ CabO I) 0.054 

CO I~' 0.0016 

W :t; 0.0008 

Gl.'l$$ Pl.'l' 0.00076 

:t.CO I~b U)ct; 0.00073 

Gypnm &oar.r 0.00017 

PI('A'OOd 0.00012 

Fl:.e rlu lla1JH &oard 0.0005 3 

c • !Jbc..'lrd 0.000 IS 

.O:..Ha~d CO I~' 0.00026 PI.U~ d)O<Ifd 0.00016 

c atlm ill~' &oard 0.00013 

.O:..IIIl'lll<t ill~' 61:.::1; 0.000" 

Gl.'l$$ Fb~I U 11.'11JH 0.000037 

Eq;.; IOHI ($t{IU~ 0.000034 

UH ~;.; ln d ll ~ El' IV<tiU 

~-.~~~: «e J . J.M::<-. Prn::'*;«S,-:r;o.'<-r •• . 

Select Material 

M"l" t H Scroll b d& r~d m11~tlill 1h~n Click on •&l&c11on 

:t'lffll, ~'\'C l":ct Zi <>. 

20.00 11 

25.00 11 

12.00 11 

3.00 11 

8.00 11 

6.00 in 

0.0016 \'Iol ·l~ 
13-17

PREDICTIIIG FlASHOVER HEAT RELEASE RATE 

METHOD OF McCAFFREY, QUIIITIERE, AIID HARKLEROAD {MQH) ~-.,~rr;,;$/=l" H:Ird»c. ('(t=l'f:> l"UC< _-t v. r.g, 3"' adl' v, ~'\):Z, l"~ )> X\:. 

= 610 v(h~., , A .. (\tl,.)) 

\Aihere 0 10 =heat release r.ne necessary for 1ashover (kVll) 

~., = e~cti\<e heattrans~rcoeflcient (kWhn1·K) 

A = 10tal area of1he corrpartment endosing surtlce boundaries e:mluding area of vent openings (m") 

A·= area of ventilation opening (m') 

h., = height ohentilation opening (m) 

Heat Transfer Coefficiert Calculation 

~., = k/6 A ssuningthat ccmpartment has been heatedthoro~.ghly befcre flashover, i.e., t > t,.. 

mere hJ.. = e~cti'W heattrans~rcoeflcient (kWhn2-K) 

k =interior lininQ 1hennal conductiWv(kVllhn·K) 

6 =interior lining thickness (m) 

~., = 0.010 kW.tn"·K 

Area d Ventilaticn Openirg C<llculaticn 

A, = (wJ (h,) 

mere A .. = area of ventilation opening (m') 

w ... = toent width (m) 

h ... = vent height (m) 

2.23 m:t 

Area d Ccmpartment Enclosing Surface Bcundaries 

A= [2(w. x 1.)+ 2(h. x w..) +2(h. x 1..)·"' 

mere A = 10tal area of1he corrpartment endosing surtlce boundaries e:mluding area of vent openings (m") 

w .. =compartment width (m) 

= corrpartment length (m) 

~ =compartment height (m) 

A·= area of ventilation opening (m") 

A= 191.01 m:r 

Minimun Heat ~lease Ratefcr Flash:lver 

610 

METHOD OF BABRAUSKAS ~'tl~rr:~ :SJ=I"=H:Ird»c.\ ('(!=1'1" , !"~~"T v. r.Q, 3"' &lll:n , ~. P~H ~IS •. 

Oto = 750 A .. (\tl,.) 

mere QtO =heat release m:e necessary for 1ashover (kVll) 

A .. = area of ventilation opening (m') 

~ =height ohen1ilation opening (m) 

Minimun Heat ~lease Ratefcr Flash:lver 

750 
13-18

METHOD OF THOMAS 't rr:~ :SFI"= H:Ird»c.\ ('(FII'l" ~"T ~v.~ r.Q, 3"' &lll :n , . P~H ISO. 

mere OtO =heat release m:e necessary for 1ashover (kVll) 

A = 10tal area of1he corrparment endosing surDce boundaries e:mluding area of vent openings (m') 

A·= area of ventilation opening (m") 

~ =height of~n1ilation opening (m) 

Minimun Heat ~lease Ratefcr Flash:lver 

9.Jmmarv of Re9.Jit 

USKAS 

I 

The abotte calcola1ions are based on principles developed in the SFPE Handbook of Fire 

Protection Blgineering, 31\l 6:1ition, 2002. 

Calcol31ions are based on cel'13in assumptions and have inherent limitations. The results 

of such calculations mayor may not ha\te reasonable predictive capabilities for a gi\ten 

siruation, and should only be int»lrpre~d by an ini:lnned user. 

J:lthough each calculation in 1he spreadsheet has been verified with the results of hand 

calculation, there is no absolute guarame ofthe accuracyofthese calcolations. 

Pnyquestions, comments, concerns. and suggestions, or to repon an error(s) in lhe 

spreadsheets, please send an email to nxi@JlroQovormxs3@JlroQOV. 
13-19

Example Problem 13.10-2

Problem Statement

Consider c c c a compartment 20 ft wide x 25 ft long x 12 ft high (w x l x h ), with an opening 3 ft wide

and v v 8 ft high (w x h ). The interior lining material of the compartment is 5/8 in. gypsum. Calculate

PFO the HRR necessary for flashover, , and the post-flashover compartment temperature, T .

Solution

Purpose:

(1) Determine the heat release rate for flashover for the given compartment.

Assumptions:

(1) Natural Ventilation

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 13_Compartment_Flashover_Calculations.xls

(click on Post_Flashover_Temperature to calculate the post-flashover temperature)

(click on Flashover-HRR to calculate the HRR for flashover)

FDT Input Parameters: s

c

-Compartment Width (w ) = 20 ft

c

-Compartment Length (l ) = 25 ft

c

-Compartment Height (h ) = 12 ft

v

-Vent Width (w ) = 3 ft

v

-Vent Height (h ) = 8 ft

-Interior Lining Thickness (*) = .63 in. (Flashover-HRR only)

-Select Material: Gypsum Board (Flashover-HRR only)

Results*

Post-Flashover Compartment

Tempe PFO rature (T )

°C (°F)

HRR for Flashover

(kW)

Method of Law Method

of MQH

Method of

Brabauskas

Method of

Thomas

811 (1,492) 1,621 2,611 2,806

 *see spreadsheet on next page
13-20

Spreadsheet Calculations

(a) FDT : 13_Compartment_Flashover_Calculations.xls (Post_Flashover_Temperature) s

CHAPTER 13. PREDICTING COMPARTMENT POST-FLASHOVER 

TEMPERATURE 

Version 1805.0 

The following calculations estimate the compartment post-flashover remper ature. 

Parameters in YELL OW CELLS are Entered by the User. 

All subsequent output values are calculated by the spreadsheet and based on values specified in the input 

pa• ameters. This spreadsheet is protected and secure to avoid errors due to a wrong entrv in a cel(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

COMPARTMENT INFORMATION 

Co mp artme nt W idlh ( IA0 

Compartment Length (I:) 

Compartment Height(h:) 

Vent Width (w.<) 

Vent Height (ht~) 

20.00 

25.00 

12.00 

3.00 

8.00 

Calculate 

PREDICTING COMPARTMENT POST .fLASHOVER TEMPERATURE 

METHOD OF MARGARET LAW 

RU: 1: •o: :S,:PE ,"'{;?,; d!V«i ;:t! l"R P!V;\>\;fVfi Et:g ll,...,\',;G J " 5.1 t~\'f. 200t, Pi?'if~ $3. 

TPF {II\ =6000(1 • e<l.l!')/(vO) 

• 

• 

• 

• 

• 

Where TPFO {Ill = m~imum compartment post-flashover temperature (°C) 

0= ventilation factor 

Where 0= (AT· A,) I A, (vh,) 

6.0~ 111 

7.62 .... 

3.6576 Ill 

0.9 U Ill 

2.433 111 

AT= total area of the compartment enclosing surface boundaries excluding area of vent openings (ml 

~=area ofventilation opening (m) 

h'-' =height of ventilation opening (m) 

Area of Ventilation OpE'flinA Calc:ulction ""'= (w,)(h,) 

Where 

A,= 

~=area ofventilation opening (m) 

WJ= ventwidth(m) 

ht< =vent height (m) 

223 m.: 

Area of CompartmE'flt Enclosing Surface Boundaries 

AT= [2(1AA:X l:)+ 2(1\:x~AA;)+2(h x l:))· AJ 

Where AT= total area of the compartment enclosing surface boundaries excluding area of vent openings (m") 

w.: = compartmentwidth (m) 

1: = compartment length (m) 

he= compartment height(m) 

A') = area ofventilation opening (m) 

19101 m'" 
13-21

Ventilation Factor Calculation 

0= (AT· A,)/ A,(vh,) 

Where 0= ventilation factor 

AT= total area of the compartment enclosing surface boundaries excluding area of vent openings (ml 

A') = area ofventilation opening (m) 

h'-' =vent height (m) 

5422 m·• ~ 

Compartment Post-Flashover Terrpercture Calculation 

TPFO {Ill = 6000 (1 • e" ·':) /(vO) 

The above calculations are based on principles developed in the SFPE Handbod< of Fire 

Pro~ction Engineering, 3

14 Edition, 2002. 

Calculations are based on certain assumptions and have inherent limitations. The results of 

such calculations may or may not have reasonable predictive capabilities for a given situation, 

and should only be in~rpreted by an informed user. 

AHhough each calculation in the spreadsheet has been veri1ied with the results of hand 

calculation, there is no absolute guarantee of the accuracy of these calculations. 

ArPJ questions, comments. concerns. and suggestions, or to report an error(s) in the 

spreadsheets. please send an email to rod@nrc.gov or mxs3@nrc.gov. 
13-22

(b) FDT : 13_Compartment_Flashover_Calculations.xls (Flashover_HRR) s

CHAPTER 13. PREDICTING COMPARTMENTFLASHOVER HEAT RELEASE RATE 

Version 1805.0 

Th fOI.)Wiig ca 'IO,_ $ 1Jil a' 1U Ill" .... Ull hat ~ <16~ 1<1, ~<IUI ~d to Q;llllp<t11111Ut 'IL. O!J~I. 

Pllrlllfl$'f' ln YEllOWCEllS ilr$ Ent~nd by Uu Uur. 

Pllrlllfl $'rl In G REEII CEllS ilr$ AUtolflll11CIIIIJ' h iHUd fi'OIQ 1U DROP OOVVII f.1E IIU for 1ll$ t.1 ~ter l h iHUd. 

lo II :<$ ~q iUt I1j lt lt U al~ cat:l 1.1t~d by ~ pl~<ld$ •Htaul b.'IHd 0 1 tJ<tltH p~ ifl?d II ~ " Pit 

p<n<llll$' " · n t ' P'""' ' ' Ht ~ p1W.c'd aut • 1e b atio•:t eno" dH b a w1019 e 11J>{ 11 a o: tl('). 

Th c •aptH IIIU IIUREG $. 0Hibe teadl=* fOie <U <U<tlf$1$ ~ ma\le. 

COIII ~\.'U111 UtV'V.:IQ ;, ~ 

COIIIP,'II111 Ut '* l gt• (I;) 

COIIIP,'U111 ut HH;JU (• c) 

vutv·v.:ru ;;.N0 

w ltH e•;~ •t ~ 

''''bl lllllg TU:tae" @) 

"' lbllllllg Th Dll<tiCOid i CUJit{ ;J:) 

THERMAL PROP ERTlE$ OATA 

l.latHI.'II Th hi a iCOUIICUJit{ 

I; f;V\1/hl-1\i 

.O:..IUJ'IIIIIIl Q>Ue) 0200 

StH I (OS~ Cabo •) 0.054 

co '~' 0.0016 

W:t; 0.0008 

Gl.'l$$ Pl.'l' 0.00076 

:t.Co r~b U)ct; 0.00073 

Gypnm &oar.l 0.00017 

PI('A'OOd 0.00012 

Fl;.; flU lla1JH 60ald 0.0005 3 

c • !Jbc..'lld 0.000 IS 

:..ua~d Co r~' 0.00026 PI. ~ d)O<Ifd 0.00016 

c atlm 1•• ' 6oa1d 0.00013 

.:.."m 11a 11• ' 6 to::•: 0.000" 

Gl.'l$$ Fb~I U 11.'11JH 0.000037 

Eq;.; UIHI ($t{IU~ 0.000034 

UH ~;.e ln d ~ E•' IV<tiU ~-.~~~: e J . J.M::<-. Prn::'*;«S ,";».'<' r •• . 

Select Material 

L:f.prum ryprq H 

Scroll b d& r~d m ~~~tlill 1h~n Click on •&l&c11on 

:t'lffll, ~'\'C l":ct Zi<>. 
13-23

PREDICTIIIG FlASHOVER HEAT RELEASE RATE 

METHOD OF McCAFFREY, QUIIITIERE, AIID HARKLEROAD {MQH) ~-.,~rr;,;$/=l" H:Ird»c. ('(t=l'f:> l"UC< _-t v. r.g, 3"' adl' v, ~'\):Z, l"~ )> X\:. 

= 610 v(h~., , A .. (\tl,.)) 

\Aihere 0 10 =heat release r.ne necessary for 1ashover (kVll) 

~., = e~cti\<e heattrans~rcoeflcient (kWhn1·K) 

A = 10tal area of1he corrpartment endosing surtlce boundaries e:mluding area of vent openings (m") 

A·= area of ventilation opening (m') 

h., = height ohentilation opening (m) 

Heat Transfer Coefficiert Calculation 

~., = k/6 A ssuningthat ccmpartment has been heatedthoro~.ghly befcre flashover, i.e., t > t,.. 

mere hJ.. = e~cti'W heattrans~rcoeflcient (kWhn2-K) 

k =interior lininQ 1hennal conductiWv(kVllhn·K) 

6 =interior lining thickness (m) 

~., = 0.011 kW.tn"·K 

Area d Ventilaticn Openirg C<llculaticn 

A, = (wJ (h,) 

mere A .. = area of ventilation opening (m') 

w ... = toent width (m) 

h ... = vent height (m) 

2.23 m:t 

Area d Ccmpartment Enclosing Surface Bcundaries 

A= [2(w. x 1.)+ 2(h. x w..) +2(h. x 1..)·"' 

mere A = 10tal area of1he corrpartment endosing surtlce boundaries e:mluding area of vent openings (m") 

w .. =compartment width (m) 

= corrpartment length (m) 

~ =compartment height (m) 

A·= area of ventilation opening (m") 

A= 191.01 m:r 

Minimun Heat ~lease Ratefcr Flash:lver 

610 

METHOD OF BABRAUSKAS ~'tl~rr:~ :SJ=I"=H:Ird»c.\ ('(!=1'1" , !"~~"T v. r.Q, 3"' &lll:n , ~. P~H ~IS •. 

Oto = 750 A .. (\tl,.) 

mere QtO =heat release m:e necessary for 1ashover (kVll) 

A .. = area of ventilation opening (m') 

~ =height ohen1ilation opening (m) 

Minimun Heat ~lease Ratefcr Flash:lver 

750 
13-24

METHOD OF THOMAS 't rr:~ :SFI"= H:Ird»c.\ ('(FII'l" ~"T ~v.~ r.Q, 3"' &lll :n , . P~H ISO. 

mere OtO =heat release m:e necessary for 1ashover (kVll) 

A = 10tal area of1he corrparment endosing surDce boundaries e:mluding area of vent openings (m') 

A·= area of ventilation opening (m") 

~ =height of~n1ilation opening (m) 

Minimun Heat ~lease Ratefcr Flash:lver 

9.Jmmarv of Re9.Jit 

USKAS 

I 

The abotte calcola1ions are based on principles developed in the SFPE Handbook of Fire 

Protection Blgineering, 31\l 6:1ition, 2002. 

Calcol31ions are based on cel'13in assumptions and have inherent limitations. The results 

of such calculations mayor may not ha\te reasonable predictive capabilities for a gi\ten 

siruation, and should only be int»lrpre~d by an ini:lnned user. 

J:lthough each calculation in 1he spreadsheet has been verified with the results of hand 

calculation, there is no absolute guarame ofthe accuracyofthese calcolations. 

Pnyquestions, comments, concerns. and suggestions, or to repon an error(s) in lhe 

spreadsheets, please send an email to nxi@JlroQovormxs3@JlroQOV. 
13-25

Example Problem 13.10-3

Problem Statement

Consider c c c a compartment 20 ft wide x 25 ft long x 12 ft high (w x l x h ), with an opening 6 ft wide

and v v 8 ft high (w x h ). The interior lining material of the compartment is 6 in. concrete. Calculate

PFO the HRR necessary for flashover, , and the post-flashover compartment temperature, T .

Solution

Purpose:

(1) Determine the heat release rate for flashover for the given compartment.

Assumptions:

(1) Natural Ventilation

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 13.1_Compartment_Flashover_Calculations.xls

(click on Post_Flashover_Temperature to calculate the post-flashover temperature)

(click on Flashover-HRR to calculate the HRR for flashover)

FDT Input Parameters: s

c

-Compartment Width (w ) = 20 ft

c

-Compartment Length (l ) = 25 ft

c

-Compartment Height (h ) = 12 ft

v

-Vent Width (w ) = 6 ft

v

-Vent Height (h ) = 8 ft

-Interior Lining Thickness (*) = 6 in. (Flashover-HRR only)

-Select Material: Concrete (Flashover-HRR only)

Results*

Post-Flashover Compartment

Tempe PFO rature (T )

°C (°F)

HRR for Flashover

(kW)

Method of Law Method

of MQH

Method of

Brabauskas

Method of

Thomas

1084 (1,982) 2,266 5,223 4,105

 *see spreadsheet on next page
13-26

Spreadsheet Calculations

(a) FDT : 13_Compartment_Flashover_Calculations.xls (Post_Flashover_Temperature) s

CHAPTER 13. PREDICTING COMPARTMENT POST-FLASHOVER 

TEMPERATURE 

Vet·sion 1805.0 

The following calculations estimate the compartment post-flashover ~mper ature. 

Para mel a-s in YELL OW CELLS are Enta-ed by the User. 

All subsequent output values are calculated by the spreadsheet and based on values specified in the input 

parameters. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a cel(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

COMPARTMENT INFORMATION 

Compartment Width (IA0 

Compartment Length (l:) 

Compartment Height(h:) 

Vent Width (WJ) 

Vent Height (ht~) 

20.00 

25.00 

12.00 

6.00 

8.00 

Calculate 

PREDICTING COMPARTMENT POST .fLASHOVER TEMPERATURE 

METHOD OF MARGARET LAW R~'lf I? •o: :s ,:PE ,"'{;?,; cb\l«i ~ ne- Pro:r.>o;t\lfi t: t.""'r,•~G J " 5:f t~\'f. 2002, Pi?'if~ $3. 

TPFO{II\~ =6000(1 • e<l.l!')/(vO) 

• 

• 

• 

• 

• 

Where TPFO {Ill~ = m~imum compartment post-flashover temperature (°C) 

0= ventilation factor 

Where 0= (AT· A,) I A, (vh,) 

0.0~ .... 

7 .G2 m 

3.6576 .... 

1.829 Ill 

2.433 Ill 

AT= total area of the compartment enclosing surface boundaries excluding area of vent openings (ml 

~=area ofventilation opening (m) 

h'-' =height of ventilation opening (m) 

Area of Ventilation OpE'flinA Calc:ulction ""'= (w,)(h,) 

Where 

A,= 

~=area ofventilation opening (m) 

WJ= ventwidth(m) 

ht< =vent height (m) 

4A6 m.: 

Area of CompartmE'flt Enclosing Surface Boundaries 

AT= [2(1AA:X l:)+ 2(1\:x~AA;)+2(h x l:))· A J 

Where AT= total area of the compartment enclosing surface boundaries excluding area of vent openings (m") 

w.: = compartmentwidth (m) 

1: = compartment length (m) 

he= compartment height(m) 

A') = area ofventilation opening (m) 

188.78 m'" 
13-27

Ventilation Factor Calculation 

0= (AT· A,)/ A,(vh,) 

Where 0= ventilation factor 

AT= total area of the compartment enclosing surface boundaries excluding area of vent openings (ml 

A') = area ofventilation opening (m) 

h'-' =vent height (m) 

26A7 m·• ~ 

Compartment Post-Flashover Terrpercture Calculation 

TPFO {Ill = 6000 (1 • e" ·':) /(vO) 

The above calculations are based on principles developed in the SFPE Handbod< of Fire 

Pro~ction Engineering, 3

14 Edition, 2002. 

Calculations are based on certain assumptions and have inherent limitations. The results of 

such calculations may or may not have reasonable predictive capabilities for a given situation, 

and should only be in~rpreted by an informed user. 

AHhough each calculation in the spreadsheet has been veri1ied with the results of hand 

calculation, there is no absolute guarantee of the accuracy of these calculations. 

ArPJ questions, comments. concerns. and suggestions, or to report an error(s) in the 

spreadsheets. please send an email to rod@nrc.gov or mxs3@nrc.gov. 
13-28

(b) FDT : 13_Compartment_Flashover_Calculations.xls (Flashover_HRR) s

CHAPTER 13. PREDICTING COMPARTMENTFLASHOVER HEAT RELEASE RATE 

Version 1805.0 

Th fOI.)Wiig ca• 'IO,_ $ 1Jil a' 1U Ill" .... Ull hat I~ <16~ 1<1, I~ IUI ~d to Q;llllp<t11111Ut 'IL. O!J~I. 

Pllrlllfl$,ri iO YEllOWCEllS ilr$ Ent~nd bj' UU Uur. 

Pllrlllfl $'rl In G REEII CEllS ilr$ AUtolflll11CIIIIJ' h iHUd fi'OIQ 1U DROP OOVVII f.1E IIU for 1ll$ t.1 ~ter l h iHUd . 

. :. II :<$ ~q iUt I1j lt lt U al~ cat:l 1.1t~d by ~ pl~<ld$ •Htaul b.'IHd o • tJ<tltH p~ ifl?d II ~ " Pit 

p<n<llll$' " · n t ' P'""' ' ' Ht ~ p1W.c'd aut • 1e b atio•:t eno" dH b a w1019 e 11J>{ 11 a o: tl(') . 

Th c•aptH IIIU IIUREG $. 0Hibe teadl=*fOie <U <U<tlf$1$ ~ ma\le. 

COIII \.'U111 UtV"V.:IQ ;, ~ 

COIIIP,'II111 Ut '* l gt• (I;) 

COIIIP,'U111 ut HH;JU (• c) 

VutV">H:IU ;;.N0 

w ltH e•;~ •t ~ 

''''bl lllllg TU:tae" @) 

"' lbllllllg Th Dll<tiCOid i CUJit{ ;J:) 

THERMAL PROP ERTlE$ OATA 

l.latHI.'II Th hi a iCOUIICUJit{ 

I; f;V\1/hl-1\i 

.0:..1111'1 , ...... ll ) 0 2 00 

StH I ,PS~ CabO I) 0.054 

CO I~' 0.0016 

W :t; 0.0008 

Gl.'l$$ Pl.'l' 0.00076 

:t.CO I~b U)ct; 0.00073 

Gypnm &oar.r 0.00017 

PI('A'OOd 0.00012 

Fl:.e rlu lla1JH &oard 0.0005 3 

c • !Jbc..'lrd 0.000 IS 

.O:..Ha~d CO I~' 0.00026 PI.U~ d)O<Ifd 0.00016 

c atlm ill~' &oard 0.00013 

.O:..IIIl'lll<t ill~' 61:.::1; 0.000" 

Gl.'l$$ Fb~I U 11.'11JH 0.000037 

Eq;.; IOHI ($t{IU~ 0.000034 

UH ~;.; ln d ll ~ El' IV<tiU 

~-.~~~: «e J . J.M::<-. Prn::'*;«S,-:r;o.'<-r •• . 

Select Material 

M"l" t H Scroll b d& r~d m11~tlill 1h~n Click on •&l&c11on 

:t'lffll, ~'\'C l":ct Zi <>. 

20.00 11 

25.00 11 

12.00 11 

6.00 11 

8.00 11 

6.00 in 

0.0016 \'Iol ·l~ 
13-29

PREDICTIIIG FlASHOVER HEAT RELEASE RATE 

METHOD OF McCAFFREY, QUIIITIERE, AIID HARKLEROAD {MQH) ~-.,~rr;,;$/=l" H:Ird»c. ('(t=l'f:> l"UC< _-t v. r.g, 3"' adl' v, ~'\):Z, l"~ )> X\:. 

= 610 v(h~., , A .. (\tl,.)) 

\Aihere 0 10 =heat release r.ne necessary for 1ashover (kVll) 

~., = e~cti\<e heattrans~rcoeflcient (kWhn1·K) 

A = 10tal area of1he corrpartment endosing surtlce boundaries e:mluding area of vent openings (m") 

A·= area of ventilation opening (m') 

h., = height ohentilation opening (m) 

Heat Transfer Coefficiert Calculation 

~., = k/6 A ssuningthat ccmpartment has been heatedthoro~.ghly befcre flashover, i.e., t > t,.. 

mere hJ.. = e~cti'W heattrans~rcoeflcient (kWhn2-K) 

k =interior lininQ 1hennal conductiWv(kVllhn·K) 

6 =interior lining thickness (m) 

~., = 0.010 kW.tn"·K 

Area d Ventilaticn Openirg C<llculaticn 

A, = (wJ (h,) 

mere A .. = area of ventilation opening (m') 

w ... = toent width (m) 

h ... = vent height (m) 

4.48 m:t 

Area d Ccmpartment Enclosing Surface Bcundaries 

A= [2(w. x 1.)+ 2(h. x w..) +2(h. x 1..)·"' 

mere A = 10tal area of1he corrpartment endosing surtlce boundaries e:mluding area of vent openings (m") 

w .. =compartment width (m) 

= corrpartment length (m) 

~ =compartment height (m) 

A·= area of ventilation opening (m") 

A= 188.78 m:r 

Minimun Heat ~lease Ratefcr Flash:lver 

610 

METHOD OF BABRAUSKAS ~'tl~rr:~ :SJ=I"=H:Ird»c.\ ('(!=1'1" , !"~~"T v. r.Q, 3"' &lll:n , ~. P~H ~IS •. 

Oto = 750 A .. (\tl,.) 

mere QtO =heat release m:e necessary for 1ashover (kVll) 

A .. = area of ventilation opening (m') 

~ =height ohen1ilation opening (m) 

Minimun Heat ~lease Ratefcr Flash:lver 

750 
13-30

METHOD OF THOMAS 't rr:~ :SFI"= H:Ird»c.\ ('(FII'l" ~"T ~v.~ r.Q, 3"' &lll :n , . P~H ISO. 

mere OtO =heat release m:e necessary for 1ashover (kVll) 

A = 10tal area of1he corrparment endosing surDce boundaries e:mluding area of vent openings (m') 

A·= area of ventilation opening (m") 

~ =height of~n1ilation opening (m) 

Minimun Heat ~lease Ratefcr Flash:lver 

9.Jmmarv of Re9.Jit 

USKAS 

I 

The abotte calcola1ions are based on principles developed in the SFPE Handbook of Fire 

Protection Blgineering, 31\l 6:1ition, 2002. 

Calcol31ions are based on cel'13in assumptions and have inherent limitations. The results 

of such calculations mayor may not ha\te reasonable predictive capabilities for a gi\ten 

siruation, and should only be int»lrpre~d by an ini:lnned user. 

J:lthough each calculation in 1he spreadsheet has been verified with the results of hand 

calculation, there is no absolute guarame ofthe accuracyofthese calcolations. 

Pnyquestions, comments, concerns. and suggestions, or to repon an error(s) in lhe 

spreadsheets, please send an email to nxi@JlroQovormxs3@JlroQOV. 
14-1

CHAPTER 14. ESTIMATING PRESSURE RISE

ATTRIBUTABLE TO A FIRE IN A CLOSED COMPARTMENT

14.1 Objectives

This chapter has the following objectives:

• Discuss some systems of pressure measurement.

• Explain how to calculate pressure rise.

• Define relevant terms, including pressure rise.

14.2 Introduction

In a closed compartment or a compartment with small leakages, the release of heat from the

combustion process could cause compartment pressure to rise as a result of the volumetric

expansion of gases. It is this pressure rise that drives the mass flow out, and prevents mass flow

into the compartment. In Chapter 2, we referred to this as the first stage of the fire.

When thermal energy rapidly accumulates in the form of hot gases, and the compartment has small

openings to the surroundings, this pressure rise is very rapid and any hydrostatic pressure

differences with height are negligible. For example, an addition of 100 kW to a 60-m (2,119-ft )

3 3

enclosure with an opening of 0.01 m (0.10 ft ) will cause a steady-state pressure rise of .1,000 Pa 2 2

(0.14 psi) in several seconds. The hydrostatic pressure difference decreases at a rate of 10 Pa

(0.0014 psi) per meter as the height increases. In this case, we see that the difference is negligible

and the vent flow is determined by the pressure rise caused by the volumetric expansion of gases.

Figure 14-1 illustrates the overpressure-time profile in an enclosure.

Figure 14-1 Overpressure Generated at a Fixed Location

Failure of a compartment due to pressure rise from a fire would be extremely rare. The vast

majority of compartments have some form of leakage. Pressure rise (and buoyancy) are important

to recognize in fire dynamic analysis because the increase in pressure can cause smoke and other

products of combustion to be transported into adjoining compartments.
14-2

14.3 Definition of Pressure

Pressure can be defined as the amount of force brought to bear on some unit area of an object.

When we press our thumb down on a table, we are applying force on the table. The harder we

press, the greater the force, and the greater the pressure we apply to the table’s surface.

Similarly, the air in the sky above us presses down on our bodies and all objects around us with a

pressure of approximately 14.7 pounds per square inch (psi) of surface area. This pressure, which

is essentially the average air pressure at sea level, is also known as one standard atmosphere.

A pressure of two atmospheres generally means that a pressure of 29.4 psi is present, or two times

the standard atmospheric pressure of 14.7 psi.

We emphasize the word “generally” because pressure also has absolute and relative scales of

measurement. The 14.7 psi of atmospheric pressure at sea level is an absolute measurement,

which is more properly presented in units of pounds per square inch-absolute, or psia for short.

Zero psia refers to a complete absence of pressure, such as one might find in the perfect vacuum

of outer space. By contrast, the most common relative scale of measurement, which is primarily

used only in the United States, presents numerical values in terms of gauge pressure, where a

reading of zero matches an absolute pressure of one standard atmosphere. In this system,

an absolute pressure of 15.7 psia would be expressed as 1.0 pound per square inch-gauge,

or 1.0 psig for short. Thus, two atmospheres of absolute pressure would be equivalent to

one atmosphere gauge pressure (Handbook of Chemical Hazard Analysis Procedures).

Among the other systems of pressure measurement that are of an absolute nature, the most

common include the following examples:

• Millimeters of mercury (mm Hg): 760 mm Hg equal one standard atmosphere.

• Inches of mercury (in. Hg): 29.9 in. Hg equal one standard atmosphere.

• Pascals (Pa) or Newton per square meter (N/m ): 101,325 Pa or 101,325 N/m 2 2

equal one standard atmosphere.

• Bars: 1.01325 bars equal one standard atmosphere.

2 2 • Inches of water (in. H O): 407.6 in. H O equal one standard atmosphere.

Inches of water and inches of mercury are not commonly used in the scientific community, with the

exception that meteorologists have traditionally reported current atmospheric pressures in inches

of mercury. Nonetheless, it is beneficial to know of their existence.
14-3

14.4 Pressure Rise Calculations

As previously discussed, the combustion process raises the temperature of a gaseous system.

This increase in temperature, in turn, causes a pressure rise attributable to expansion of the gases.

According to the ideal gas law, when heat is added to an ideal gas in a fixed volume, the pressure

must rise in response to the temperature. In a building fire situation, the resulting pressure and the

rate of pressure rise are often kept very small by gas leaks through openings in the walls of the

buildings (such as cracks around windows and doors). However, situations may arise where the

enclosure can be considered to be well sealed, such as certain compartments on ships.

According to Karlsson and Quintiere (1999), the maximum pressure difference inside a compartment

as a result of expansion of gases is given by the following expression:

 (14-1)

Where:

P = compartment pressure attributable to combustion (atm)

Pa = initial atmospheric pressure (atm)

= heat release rate of the fire (kW)

t = time (sec)

V = compartment volume (m )

3

a

 = ambient air density (kg/m )

3

v

c = specific heat of air at constant volume (kJ/kg-K)

v

 [values of c range from 0.71 to 0.85 kJ/kg-K]

Ta = ambient air temperature (K)

14.5 Assumptions and Limitations

The method discussed in this chapter is subject to several assumptions and limitations:

(1) The energy release rate is constant.

(2) The mass loss rate of the fuel is neglected in the conversion of mass.

(3) The specific heat does not change with temperature.

(4) The hydrostatic pressure difference over the height of the compartment is ignored

and assumed to be negligible compared to the dynamic pressure.
14-4

14.6 Required Input for Spreadsheet Calculations

The user must obtain the following information before using the spreadsheet:

(1) compartment width (ft)

(2) compartment length (ft)

(3) compartment height (ft)

(4) fire heat release rate (ft)

(5) time after ignition (s)

14.7 Cautions

(1) Use (14_Compartment_Over_Pressure_Calculations.xls) spreadsheet on the CD-ROM

for calculations.

(2) Make sure to input values using correct units.

14.8 Summary

According to the ideal gas law, when heat is added to an ideal gas in a fixed volume, the pressure

must rise in response to the temperature. In a building fire situation, the resulting pressure and the

rate of pressure rise are often kept small by gas leaks through openings in the walls of the buildings

(such as through penetrations and cracks around windows/doors). However, situations may arise

where the enclosure can be considered to be well sealed. It is important to recognize the increase

in pressure within the fire compartment will cause products of combustion to also be transported

into adjacent spaces.

The purpose of this chapter is to provide simple analytical method for calculating the dynamic

pressure build-up in a closed compartment. We then use the results to show that the rapid

pressure rise. This result can be used to justify the so-called “constant pressure assumption,”

which is typically used when examining a “leaky” compartment fire.

14.9 References

Handbook of Chemical Hazard Analysis Procedures, Federal Emergency Management Agency

(FEMA), US Department of Transportation (DOT), and U.S. Environmental Protection Agency

(EPA).

Karlsson, B., and J.G. Quintiere, Enclosure Fire Dynamics, Chapter 8, “Conservation Equations and

Smoke Filling,” CRC Press LLC, New York, pp. 181–225, 1999.
14-5

14.10 Problems

Example Problem 14-10.1

Problem Statement

A closed compartment in a facility pump room has dimensions 10 ft wide x 12 ft long x 10 ft high

c c c

(w x l x h ). A fire starts with a constant HRR of = 100 kW. Estimate the pressure rise

attributable to the expansion of gases after 10 seconds.

Solution

Purpose:

(1) Estimate the pressure rise in the compartment 10 seconds after ignition.

Assumptions:

(1) The energy release rate is constant.

(2) The mass rate of the fuel is neglected in the conversion of mass.

(3) The specific heat is constant with temperature.

(4) The hydrostatic pressure difference over the height of the compartment is negligible

compared to the dynamic pressure.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 14_Compartment_Over_Pressure_Calculations.xls

FDT Input Parameters: s

c

-Compartment Width (w ) = 10 ft

c

-Compartment Length (l ) = 12 ft

c

-Compartment Height (h ) = 10 ft

-Fire Heat Release Rate = 100 kW

-Time After Ignition (t) = 10 sec

Results*

Pressure Rise 11.90 kPa (1.73 psi)

*see spreadsheet on next page
14-6

Spreadsheet Calculations

FDT : 14_Compartment_Over_Pressure_Calculations.xls s

CHAPlER 14. ESllMATING PRESSURE RISE DUE TO A FIRE IN A 

CLOSED COMPARTMENT 

Version 1805.0 

The folloWng cala.Aiations estimate the pressure rise in a compartment due to fire and combustion. 

Parnmeters in YELLOW CELLS are Enteredby theUser • 

.AJI subsequent output values are cala.Aiated by the spreadsheet and based on values sped1ied in the input 

parameters. This spreadsheet is protected and secure to avoid errors due to a wong entry in a cell(s). 

The chapter in the NUREG guide should be read before an analysis ism ade. 

INPUT PARAMElERS 

COMPARTIYI:IIT IIIFORMATIOII 

Compartmenl Width ('110 

Compartmenl Length (1,) 

Compartmenl Height (h,) 

Fire Heat Release Rate (Q) 

Time a1ter Ignition ~) 

.Ambient .AJr Temperature (T ~) 

AMBlE liT COIIDITIOIIS 

Initial .Atmospheric P ressure (P ~ 

Specific Heat of Air at Constant Volume (c..) 

(Nole: Values ofc, ranges from 0.71 to 0.85 kJII<g-k) 

I'm bienll'ir Dens~y (JJJ 

10.00 t 

12.00 t 

10.00 t 

100.00 kW 

10.00 

77.00 

Calculat e 

14.701psi 

L... ___ _;0;:,;.7:..1:Jk.JA<g·K 

Note: Air density Wll automatically correct Wth Ambient ,Ajr Temperature (T ~Input 

'-----

3.05 m 

3.66 m 

3.05 m 

25.oo •c 

211!.00 K 

101.35 kPa 
14-7

lvETHOD OF KARLSSON AND QUINTIERE P,~tru o: a-ltS.S..\'f a-,;dO:;h t~:~. =-;l;v" e "'RQtjjjll]l($, 1999. Pa-(? 1 92 . 

(P· P,.)/P,. = Qt/(Vp,. c, T,.) 

Where P =compartment pressure due to fire and combustion (kP a) 

P,. =initial atmospheric pressure (kP a) 

Q =heat release rail>! of the fire (kVll) 

t= time after ignition (sec) 

V= compartmentvolume(m:t) 

p, = ambient densio/ (k9"m' ) 

c.·= specific heat of air at constdnt volume (kJA<g·J-9 

T,. =ambient air ~mperature (J-9 

Comp~ment \oblume Calc:ulal:ion 

V= w..x L x h.. 

Where 

V= 

V= volume of the comoartment(m) 

~~~t = compartmentwidlh(m) 

l =compartment length (m) 

h. = compartment height (m) 

33.93 :~ 

PressLre Rise in Corrpart mert 

(P· P,.)/P,. = Qt/(Vp,. c, T,.) 

(P-P,y P,. = 0.117 a1m 

Multiplying by the atmospheric pressure 

Gives a pressure difference= 

This example shews that in a very short time the pressure in a closed compartment rises to 

quite larQe value. 

Most buildings have le~s of some sort The above example indicates that even though a fire 

compartment may be closed, the pressure is very rapid and would presumably lead ro sufficient 

le_.s ro preventfurther pressure rise from ocwrring. We will use this conclusion when dealing 

with rises in endosures with smallle,..s. 

The above calculations are based on principles developed in the Endosure Fire D\lnamics. 

Calculations are based on certain assumptions and have inherent limitations. The results of 

such calculations may or may not have reasonable predictive capabilities for a given situation, 

and should only be interpreted by an informed user. 

Although each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolub! guarantee of the accurac.y of these calculations. 

Arfl/ questions, commen1s, concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to rod@nrc.gov or rro<:s3@nrc.gov. 
14-8

Example Problem 14.10-2

Problem Statement

A facility has a sealed compartment (assume zero leakage) with a blowout panel that is designed

to fail at two atmospheres. The compartment is 20 ft wide x 25 ft long x 10 ft high. A fire is

assumed with a constant heat release rate of 255 kW.

At what time (sec) does the blowout panel fail?

Solution

Purpose:

(1) Estimate the time after ignition the pressure reaches 2 atm (202.5 kPa).

Assumptions:

(1) The energy release rate is constant.

(2) The mass rate of the fuel is neglected in the conversion of mass.

(3) The specific heat is constant with temperature.

(4) The hydrostatic pressure difference over the height of the compartment is negligible

compared to the dynamic pressure.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 14_Compartment_Over_Pressure_Calculations.xls

FDT Input Parameters: s

c

-Compartment Width (w ) = 20 ft

c

-Compartment Length (l ) = 25 ft

c

-Compartment Height (h ) = 10 ft

-Fire Heat Release Rate = 255 kW

-Time After Ignition (t) = varies until output is 202.5 kPa

Results*

Time after ignition 278 sec

*see spreadsheet on next page
14-9

Spreadsheet Calculations

FDT : 14_Compartment_Over_Pressure_Calculations.xls s

CHAPlER 14. ESllMATING PRESSURE RISE DUE TO A FIRE IN A 

CLOSED COMPARTMENT 

Version 1805.0 

The folloWng cala.Aiations estimate the pressure rise in a compartment due to fire and combustion. 

Parnmeters in YELLOW CELLS are Enteredby theUser • 

.AJI subsequent output values are cala.Aiated by the spreadsheet and based on values sped1ied in the input 

parameters. This spreadsheet is protected and secure to avoid errors due to a wong entry in a cell(s). 

The chapter in the NUREG guide should be read before an analysis ism ade. 

INPUT PARAMElERS 

COMPARTIYI:IIT IIIFORMATIOII 

Compartmenl Width ('110 

Compartmenl Length (1,) 

Compartmenl Height (h,) 

Fire Heat Release Rate (Q) 

Time a1ter Ignition ~) 

.Ambient .AJr Temperature (T ~) 

AMBlE liT COIIDITIOIIS 

Initial .Atmospheric P ressure (P ~ 

Specific Heat of Air at Constant Volume (c..) 

(Nole: Values ofc, ranges from 0.71 to 0.85 kJII<g-k) 

I'm bienll'ir Dens~y (JJJ 

20.00 t 

25.00 t 

10.00 t 

255.00 kW 

278.00 

77.00 

Calculat e 

14.701psi 

L... ___ _;0;:,;.7:..1:Jk.JA<g·K 

Note: Air density Wll automatically correct Wth Ambient ,Ajr Temperature (T ~Input 

'-----

6.10m 

7.62 m 

3.05 m 

25.oo •c 

211!.00 K 

101.35 kPa 
14-10

lvETHOD OF KARLSSON AND QUINTIERE P,~tru o: a-ltS.S..\'f a-,;dO:;h t~:~. =-;l;v" e "'RQtjjjll]l($, 1999. Pa-(? 1 92 . 

(P· P,.)/P,. = Qt/(Vp,. c, T,.) 

Where P =compartment pressure due to fire and combustion (kP a) 

P,. =initial atmospheric pressure (kP a) 

Q =heat release rail>! of the fire (kVll) 

t= time after ignition (sec) 

V= compartmentvolume(m:t) 

p, = ambient densio/ (k9"m' ) 

c.·= specific heat of air at constdnt volume (kJA<g·J-9 

T,. =ambient air ~mperature (J-9 

Comp~ment \oblume Calc:ulal:ion 

V= w..x L x h.. 

Where 

V= 

V= volume of the comoartment(m) 

~~~t = compartmentwidlh(m) 

l =compartment length (m) 

h. = compartment height (m) 

141.58 :~ 

PressLre Rise in Corrpart mert 

(P· P,.)/P,. = Qt/(Vp,. c, T,.) 

(P-P,.)"P,. = 1.993 atm 

Multiplying by the atmospheric pressure 

Gives a pressure difference= 

This example shews that in a very short time the pressure in a closed compartment rises to 

quite larQe value. 

Most buildings have le~s of some sort The above example indicates that even though a fire 

compartment may be closed, the pressure is very rapid and would presumably lead ro sufficient 

le~s ro preventfurther pressure rise from ocwrring. We will use this conclusion when dealing 

with rises in endosures with smallle~s. 

The above calculations are based on principles developed in the Endosure Fire D\lnamics. 

Calculations are based on certain assumptions and have inherent limitations. The results of 

such calculations may or may not have reasonable predictive capabilities for a given situation, 

and should only be interpreted by an informed user. 

Although each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolubl guarantee of the accurac.y of these calculations. 

Arfl/ questions. comments. concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to rod@nrc.gov or rro<:s3@nrc.gov. 
15-1

CHAPTER 15. ESTIMATING THE PRESSURE INCREASE

AND EXPLOSIVE ENERGY RELEASE

ASSOCIATED WITH EXPLOSIONS

15.1 Objectives

This chapter has the following objectives:

• Define the nature and implications of an explosion.

• Explain the various causes, hazards, and effects of explosions.

• Explain how to calculate the energy released by an explosion.

• Explain how to calculate the pressure increase attributable to an explosion.

15.2 Introduction

In its most widely accepted sense, the term “explosion” means a bursting associated with a loud,

sharp noise and an expanding pressure front, varying from a supersonic shock wave to a relatively

mild wind. The term has also been extended to encompass chemical or physical/chemical events

that produce explosions.

An explosion is defined as a sudden and violent release of high-pressure gages into the environment.

The primary keyword in this definition is “rapid.” The release must be sufficiently fast so that energy

contained in the high-pressure gas dissipates in a shock wave. The second key word is “high

pressure,” which signifies that, at the instant of release, the gas pressure is above the pressure of

the surroundings. Note that the basic definition is independent of the source or mechanism by

which the high-pressure gas is produced (Senscal, 1997).

Despite this commonly accepted definition, the literature includes many other interrelations of the

concept of an explosion:

• A rapid release of high-pressure gases into the environment (Cruice, 1991).

• A sudden conversion of potential energy (chemical or mechanical) into kinetic energy in the

form of rapidly expanding gases (NFPA, 921).

• A physical reaction characterized by four elements: high-pressure gas; confinement or

restriction of the pressure; rapid production or release of that pressure; and change or

charge to the confining (restricting) structure, container, or vessel caused by the pressure

release. The generation and violent escape of gases are the primary criteria of an

explosion (NFPA 921).

• The noise or bang attributable to the sudden release of a strong pressure wave or blast

wave, which relates to the basic meaning of the word, “sudden outburst” (Bodhurtha, 1980).

• An exothermic chemical process that when occurring at constant volume, gives rise to a

sudden and significant pressure rise (Vervalin, 1985).
15-2

• In general scientific terms, an explosion is said to have occurred in the atmosphere if energy

is released over a sufficiently small time and in a sufficiently small volume so as to generate

a pressure wave of finite amplitude traveling away from the source (Baker et al., 1983).

This energy may have originally been stored in the system in a variety of forms; these

include nuclear, chemical, electrical, or pressure energy, for example. However, the release

is not considered to be explosive unless it is rapid enough and concentrated enough to

produce a pressure wave that one can hear. Even though many explosions damage their

surroundings, it is not necessary that external damage be produced by the explosion.

All that is necessary is that the explosion is capable of being heard.

While these definitions differ, they share the following characteristics of an explosion:

• release of high pressure gases

• rapid expansion of gases

• formation of a pressure wave or blast wave of sufficient intensity to be heard

The last of these characteristic is often favored by explosion investigators. The ability to be heard

enables investigations to define whether an incident was an explosion, based on what happened

and what the results were.

Explosions are often characterized by their primary means of generation (physical or chemical); this

categorization includes the following types of explosions:

• Physical explosions are those caused when the high-pressure gas is generated only by

mechanical means without any chemical change, as in the following types of explosions:

— external heating of a tank resulting in increased internal pressure and resultant

failure of the tank

— sudden release of super-heated liquid which flash-evaporates, causing a rapid

explosion

• Chemical explosions are those when the high-pressure gas is generated only by chemical

reactions without any physical or chemical interaction, as in the following:

— Combustion explosions are caused by rapid oxidation of combustion material, which

results in an explosion of gases that triggers a pressure wave. Combustion

explosions include the following types:

< dust explosions

< gas explosions

< natural gas explosions

< backdraft explosions 

< mists

— Thermal explosions are a special class of chemical explosions where the heat

released by the reaction of two or more chemical compounds results in a more rapid

reaction rate that eventually results in an explosion. These types of explosions are

a great concern in chemical processes.

— Condensed phase explosions are those caused by rapid reactions of chemical

components in the solid or liquid phase. This type of chemical explosion includes

those resulting from high explosives or propellants (solid and liquid) used for missile fuel.
15-3

— Nuclear explosions are associated with the fission or fusion of matter.

— Detonations and deflagrations are often distinguished by the speed or rate of

propagation of the combustion wave through the material. In a detonation, the flame

or combustion wave propagates through the reactants at supersonic speeds on the

order of 2,000 m/sec (6,562 ft/sec). By contrast, the rate of propagation in a

deflagration is below the speed of sound in air at 20 °C (68 °F), which is

approximately 330 m/sec (1,082 ft/sec). The fact that detonations propagate at

supersonic speeds implies the existence of a shock wave, which is the reason that

the reactions propagate so rapidly. (The shock wave compresses reactants,

causing the reaction to occur faster.) The practical distinction between detonations

and deflagrations also relates to the amount of damage caused. Specifically, the

pressure attained during a detonation can be up to 20 atmospheres (284 psi).

By contrast, the overpressure caused by the pressure in a typical deflagration wave

2 2 is on the order of 1 atmosphere (14.70 psi) for C H in air.

15.3 Explosion Hazard

The hazards associated with deflagration include catastrophic equipment failure, ejection of flame

and unburned product (possibly hazardous in its own right) into the surroundings, possible

secondary explosions leading to catastrophic facility damage, and personal injury. The following

elements must exist simultaneously in order for a deflagration to occur:

• a flammable mixture consisting of a fuel and oxygen, usually from air, or other oxidant

• a means of ignition

• an enclosure

The term “flammable mixture” denotes that the fuel and oxygen components are intimately mixed

and are each present at a concentration that falls within a flammable composition boundary

characteristic of each system of fuel, oxygen, and inert material (inert gas or solid). Ignition of a

flammable mixture occurs when a point source of sufficient energy achieves a temperature above

the ignition temperature of the mixture. All incandescent sparks (e.g., mechanical, electrical,

electrostatic) have sufficient temperature to cause ignition, but may lack sufficient energy to heat

a minimal propagating mass to its ignition temperature. A hot process surface may have a

temperature below that required for prompt ignition, but may have a large energy content. Dust

deposits on such surfaces can be subjected to accelerated self-heating and eventual ignition.

Should ignition of a flammable mixture occur within an enclosure, regardless whether of the

enclosure has ventilation points, the internal pressure will increase as necessary, to satisfy the nonsteady-state material balance equation. The time needed to achieve the maximum deflagration

pressure depends on size of the enclosure and the characteristics of the fuel, but generally can

extend up to a few hundred milliseconds. Some venting of the expanding combustion gases occurs

through normal process openings, but these are usually too small to prevent the development of

destructive pressures.
The terms “upper flammability limit” (UFL) and “lower flammability limit” (LFL) are also used

1

to describe the flammable range of gases. For our purposes, they are synonymous with UEL

and LEL respectively.

15-4

15.4 Explosive Range

A certain quantity—neither too little nor too much—of flammable gas mixed with a certain quantity

of air allows a mixture to become explosive and propagate the explosion flame. The lower and

upper boundaries of this “explosive range” are known as the lower explosion limit (LEL) and the

upper explosion limit (UEL), respectively . When the quantity of flammable gas and/or air is either 1

below or above these boundaries, the mixture is not explosive and will not propagate the explosion

flame. At the LEL or UEL, the mixture will burn when ignited, causing an insignificant flame

propagation. Between the two boundaries, there is a point at which flame propagation reaches its

maximum.

15.5 Backdraft Explosion

Fires in oxygen-starved environments result in unburned fuel, “fuel vapor,” which is a complex

mixture of combustion gases, vapors, and aerosols suspended in the smoke. If the gas layer is hot

enough (i.e., at its ignition temperature) it may immediately ignite when the fuel-rich smoke layer

mixes with air (thereby receiving adequate oxygen) when the smoke-filled compartment or building

is vented.

By contrast, when the gas layer is relatively cool, particularly in a severely oxygen-restricted fire,

the fuel vapor may not immediately ignite when the compartment or building is vented. Rather, in

such instances the ignition of the fuel vapor may be delayed until fresh air is introduced, mixes, with

the vapor, and makes its way back to the fire source. When this occurs, the flame itself becomes

the ignition source, and the ignition delay results from the time required to mix the fuel-rich smoke

layer with oxygen-rich fresh air. This phenomenon, known as a “backdraft explosion,” has the

characteristics of a premixed fuel/air deflagration.

15.6 Smoke Explosion

It is also possible for a smoldering fire to produce sufficient unburned fuel and carbon monoxide

to form a premixed combustible atmosphere. If the smoldering fire raises the temperature to the

autoignition temperature of the mixture, the smoke/gas cloud will deflagrate causing a “smoke

explosion.” Such explosions have been observed in smoldering fires involving polyurethane foams.
15-5

15.7 Unconfined and Confined Explosions

Explosions that occur in open air, known as “unconfined explosions,” are fundamentally different —

and require different countermeasures — than “confined explosions,” which occur within some sort

of containment. Confined explosions often occur in a process vessel or pipework, but may also

occur in buildings. The explosion of a flammable mixture in a process vessel or pipework may be

a detonation or a deflagration. The overpressure in a confined explosion is attributable to the

expansion of the hot gases and may be exacerbated by the release of gases through an explosion

vent (even a door or window) when the resulting turbulence produces a second pressure peak, as

illustrated in Figure 15-1 (Harris, 1983).

Figure 15-1 Pressure Peaks of an Explosion Inside a Building
15-6

Confined explosion usually will not cause an accidental release of gas in any quantity directly into

the atmosphere. Rather, such explosions usually release gases within some form of such as

compartment or building of an industrial plant. If a flammable mixture forms and is ignited under

these contained conditions, a confined gas explosion will occur. Moreover, if a gas is accidentally

released into the air, mixes with air and is ignited, the flame front travels through the mixture,

propagating in a spherical geometry whenever possible rather than remaining stationary, as

illustrated in Figure 15-2.

Figure 15-2 Propagation of Explosion Flame
15-7

15.8 Estimating the Effects of Explosions

When a firecracker or a stick of dynamite explodes, the violence and speed of the reactions taking

place produce what is referred to as either a shock wave or a blast wave. Technically speaking,

there is a difference between these two terms, but we will treat them rather interchangeably here.

Either type of wave can be thought of as a thin shell of highly compressed air and/or hot gases that

expands rapidly in all directions from the point at which the explosion is initiated. Such waves can

move at velocities exceeding the speed of sound in air, and, therefore, are capable of producing

sonic “booms,” much like those associated with supersonic aircraft. This is how significant

explosions produce a loud “bang.”

The damage caused by a shock or blast wave striking an object or a person is a complex function

of many factors, and it is well beyond the scope of this chapter to describe all of the complex

interactions involved. Instead, we will simply refer to the wave as a rapidly expanding shell of

compressed gases. We can then measure the strength of the wave in units of pressure (psi), and

we can relate the effects of peak overpressure within the wave (i.e., the maximum pressure in the

wave in excess of normal atmospheric pressure) to the level of property or personal injury that is

likely to result.

Table 15-1 lists damage effects on people and property, which might be expected to result from

explosions characterized by various peak overpressures (Clancey, 1972). It is important to note

that peak overpressures in a shock or blast wave are highest near the source of the explosion and

decrease rapidly with distance from the explosion site. Additionally, it must be noted that the extent

of damage incurred is heavily influenced by the location of the blast relative to nearby reflecting

surfaces.

Table 15-1. Estimated Damage Attributable to Explosive Overpressure

(Clancey, 1972)

Overpressure*

(psig)

Expected Damage

0.03 Occasional breaking of large windows that are already under strain.

0.04 Glass failure caused by loud noises (143 dB) or sonic booms.

0.10 Breaking of small windows under strain.

0.15 Typical glass failure.

0.40 Some damage to house ceilings; 10% window glass breakage.

0.40 Limited minor structural damage.

0.50–1.0 Windows usually shattered; some damage to window frames.

0.7 Minor damage to house structures.

1.0 Houses made uninhabitable by partial demolition. 

1.0–2.0 Failure and buckling of corrugated metal panels; housing wood panels are blown in.

1.0–8.0 Slight to serious injuries (e.g., skin lacerations from flying glass and other missiles).
Table 15-1. Estimated Damage Attributable to Explosive Overpressure

(Clancey, 1972)

Overpressure*

(psig)

Expected Damage

15-8

1.3 Slight distortion of the steel frames of clad buildings.

2.0 Partial collapse of walls and roofs of houses.

2.0–3.0 Shattering of non-reinforced concrete or cinder block walls.

2.3 Lower limit of serious structural damage.

2.4–12.2 Up to 90% eardrum rupture among exposed populations.

2.5 50% destruction of home brickwork.

3.0 Distortion of steel frame buildings; may pull away from their foundations.

3.0–4.0 Ruin of frameless steel panel buildings.

4.0 Rupture of cladding of light industrial buildings.

5.0 Snappy of wood utility poles.

5.0–7.0 Nearly complete destruction of houses.

7.0 Overturning of loaded train cars.

7.0-8.0 Shearing of flexure causes failure of 8–12-inch thick non-reinforced brick.

9.0 Demolition of loaded train cars.

10.0 Probable total destruction of building.

0.10 Up to 99% fatalities among exposed populations as a result of direct blast effects.

* These are the peak pressures formed (in excess of normal atmospheric pressure) by blast and shock waves.

For SI units, 1 psi = 6.894757 kPa.

As shown in Table 15-1, an explosion may give rise to (1) blast damage, (2) thermal effects,

(3) missile damage, (4) ground shock, (5) cratering, and (6) personal injury. Not all of these effects

arise from every explosion. For example, an aerial blast may not cause a crater.
15-9

In addition to the personal injuries and property damage caused by direct exposure to peak

overpressures, the blast wave also has the potential to cause indirect, secondary effects:

• Damage may result from missiles, fragments, and environmental debris set in motion by the

explosion or by the heat generated.

• Damage may result from forcible movement of exposed people and their subsequent impact

with ground surfaces, walls, or other stationary objects.

Many of the data on the effects of explosions come from studies of industrial and military

explosives, but an increasing amount of information is becoming available from the investigation

of process plant explosions.

15.8.1 Estimating Explosive Energy Release in a Confined Explosion

One typical explosion in an enclosure is caused by flammable gas leaking, which mixes with air in

the enclosure and subsequently ignites to cause an explosion.

The energy released by expansion of compressed gas upon rupture of a pressurized enclosure

may be estimated using the following equation (Zalosh, 1995):

(15-1)

Where:

E = explosive energy released (kJ)

 = yield (i.e., the fraction of available combustion energy participating in blast wave 

 generation)

Hc = theoretical net heat of combustion (kJ/kg)

mF = mass of flammable vapor release (kg)

The yield, , is typically in the range of 1 percent (0.01) for unconfined mass releases,

to 100 percent (1.0) for confined vapor releases (Zalosh, 1995). Table 15-2 presents the theoretical

net heat of combustion for flammable gases.
15-10

Table 15-2. Heat of Combustion, Ignition Temperature, 

and Adiabatic Flame Temperature* of Flammable Gases

Flammable Gas Heat of

Combustion

Hc (kJ/kg)

Ignition

Temperature

Tig °C (°F)

Adiabatic Flame

Temperature

Tad °C (°F)

Acetylene 48,220 755 (1,391) 2,637(4,779)

Carbon monoxide

(commercial)

10,100 765 (409) 2,387 (4,329)

Ethane 47,490 945 (1,733) 1,129 (2,064)

Ethylene 47,170 875 (1,607) 2,289 (4,152)

Hydrogen 130,800 670 (1,238) 2,252 (4,085)

Methane 50,030 1190 (2,174) 1,173 (2,143)

n-Butane 45,720 1025 (1,877) 1,339 (2,442)

n-Heptane 44,560 - 1,419 (2,586)

n-Octane 44,440 - 1,359 (2,478)

n-Pentane 44,980 - 1,291 (2,356)

Propane 46,360 1,010 (1,850) 1,281 (2,338)

Propylene 45,790 1,060 (1,940) 2,232 (4,050)

*Adiabatic flame temperature of lower limiting fuel/air mixture.

15.8.2 TNT Mass Equivalent Calculations

One of the most common methods used to estimate the effects of an explosion is to relate the

exploding fuel to trinitrotoluene (TNT). This method converts the energy contained in the flammable

cloud into an equivalent mass of TNT, primarily because blast effects of TNT have been extensively

studied as a function of TNT weight and distance from the source. Hence, we can infer the blast

effects of an explosion by relating an explosion to an “equivalent” explosion of TNT. To do so, we

relate a given fuel type and quantity to an equivalent TNT charge weight, as follows (Zalosh, 1995):

 (15-2)

Where:

WTNT = weight of TNT (kg)

E = explosive energy released (kJ)
15-11

15.8.3 Blast Effects

Blast effects can also be related to the equivalent weight of TNT using by the relationship between

the distance from the source, the charge weight, and the overpressure caused by the blast wave,

including the reflected shock wave. Figure 15-3 (Zalosh, 1995) gives the relationship between

overpressure and “ sc scaled distance” (D ) (in English and metric units). Scaled distance is the

distance at which the overpressure is calculated divided by the cube root of the TNT charge weight.

 (15-3)

Where:

Dsc = scaled distance [m/(kg) ]

1/3

D = distance at which the overpressure is calculated (m)

WTNT = weight of TNT (kg)

Figure 15-3 Ideal Blast Wave Overpressure vs. Scaled Distance

(Zalosh, 1995, © SFPE. With permission.)
15-12

15.9 Effects of Pressure on Humans and the Environments

Human beings are capable of withstanding relatively high dynamic pressures and considerably

higher static pressures. When people are fatally injured as a result of blast waves, it is usually

because of falling objects, rather than the pressure associated with the blast wave. Table 15-3

summarizes the pressure effects of blast waves on humans (Fischer et al., 1995), which also

depend on the impulse of the blast wave. With the exception of smoke gas explosions, fires seldom

reach pressures as high as those listed in Table 15-3. A maximum pressure of 8 bar is produced

if a premixed gas-air mixture is ignited inside a building. Outside a building, similar explosion

produce pressures of the same order of magnitude if the release results in an unconfined vapor

cloud explosion (UVCE). Even higher pressures result if the release causes a detonation both

inside and outside a building. However, detonations are very rare.

Usually, it is difficult to predict the pressures produced. In addition, the consequences for humans

depend to a significant degree on whether something nearby can strike people in the vicinity of the

explosion. Consequently, it is generally not worth the effort to find better values for pressure effects

on humans. Similarly, pressure effects are usually limited to a small area, and the effect of

pressure on the environment is seldom discussed.

Table 15-3. Pressure Effects on Humans

Pressure (kPa) Effect

35 kPa Limit for eardrum rupture

70 kPa Limit for lung damage

100 kPa 50-percent eardrum rupture

180 kPa 1-percent mortality

210 kPa 10-percent mortality

260 kPa 50-percent mortality

300 kPa 90-percent mortality

350 kPa 99-percent mortality
15-13

15.10 Effects of Pressure on Components

Existing literature provides only limited data on the effects of pressure on components (such as

machines); however, it appears that components are usually unaffected by pressure if they are solid

and more sensitive to pressure variations if they contain cavities. When it comes to building

elements such as windows, walls, and doors, the literature does provide acceptable data.

Table 15-4 lists typical failure pressures of such elements (Harris, 1983).

Table 15-4. Typical Failure Pressures of Some Building Elements

Element Typical Failure Pressure

(kPa)

Glass windows 2–7

Room doors 2–3

Light partition walls 2–5

50-mm-thick breeze block walls 4–5

Unrestrained brick walls 7–15
15-14

15.11 Estimating the Pressure Increase Attributable to a Confined Explosion

The combustion process raises the temperature of a gaseous system and that, in turn, increases

the pressure of the system by expanding the gases. The “ideal gas law” quantifies the effects,

as follows:

 (15-4)

Whe 1 1 2 2 re P T and P T represent the pressure and temperature at state 1 and state 2, respectively,

in a constant volume system.

The pressure increase caused by the expansion of the gases is determined by the following

equation:

 (15-5)

Assuming that the entire confining enclosure is filled with a gas/air mixture, the maximum pressure

max inside the enclosure at the end of combustion (P ) is given by the following equation:

 (15-6)

and

 (15-7)

Where:

Pmax = maximum pressure at end of combustion (kPa)

Pamb = initial ambient atmospheric pressure prior to ignition (kPa)

Tad = adiabatic flame temperature of burned gas (K)

Tamb = initial ambient temperature gas/air mixture (K)

Remember that absolute temperature (K or R) must be used in these equations. The adiabatic

flame temperature of the burned gas should be approximately the values shown for the given

flammable gas(es) in Table 15-2.
15-15

15.12 Assumptions and Limitations

The methods discussed in this chapter are subject to several assumptions and limitations:

(1) The method assumes point source blast wave energy correlation (i.e., TNT equivalent

energy).

(2) The ideal point source blast wave correlations cannot be valid within or near the flammable

vapor cloud.

(3) Flammable gases and vapors are mixed with air (or some other oxidant) in proportions

between the lower and upper flammable limits.

(4) It is important to recognize that practical applications of flammability/exposibility data for

explosion hazard evaluation should account for nonuniform or stratified vapor-air mixtures.

15.13 Required Input for Spreadsheet Calculations

The user must obtain the following information before using the spreadsheet:

(1) fuel type (material)

(2) mass of flammable vapor (lb)

(3) ambient temperature (°F)

(4) ambient pressure (psi)

15.14 Cautions

(1) Use (15_Explosion_Calculations.xls) spreadsheet on the CD-ROM for pressure increase

and explosive energy release calculations associated with explosions.

(2) Make sure to enter the input parameters in the correct units.
15-16

15.15 Summary

This chapter discusses methods of calculating the pressure increase and explosive energy release

associated with explosions. Within that content, an explosion is defined as a sudden and violent

release of high-pressure gases into the environment. The violence of the explosion depends on

the rate at which the energy of the high-pressure gases is released. The energy stored in a car tire,

for example, is capable of causing an explosive burst, but it can also be dissipated by gradual

release. In general, an explosion can release any of the basic types of energy, including

(1) physical energy (2) chemical energy.

Physical energy may take such forms as pressure energy in gases, strain energy in metals, or

electrical energy. Examples of the violent release of physical energy include the explosion of a

vessel as a result of high gas pressure and the sudden rupture of a vessel as a result of brittle

fracture. Another physical form is thermal energy, which generally play an important role in creating

the conditions for an explosion, rather than as a source of energy for the explosion itself.

In particular, superheating a liquid under pressure causes flashing of the liquid if it is let down

to atmospheric pressure.

Chemical energy is derived from a chemical reaction. Examples of the violent release of chemical

energy are explosions of a vessel as a result of the combustion of flammable gas. Chemical

explosions are either (1) uniform explosions or (2) propagating explosions. An explosion in a vessel

tends to be a uniform explosion, while an explosion in a long pipe produces a propagating

explosion.
15-17

15.16 References

Baker, W.E., et al., Explosion Hazards and Evaluation, Amsterdam Elservier Science Publishing

Company, 1983.

Bodhurtha, F.T., Industrial Explosion Prevention and Protection, McGraw-Hill Book Company,

New York, 1980.

Clancey, V.J., “Diagnostic Features of Explosion Damage,” Sixth International Meeting of Forensic

Science, Edinburgh, England, 1972.

Cruice, W.J., “Explosions,” Section 1, Chapter 5, NFPA Fire Protection Handbook, 17 Edition, th

National Fire Protection Association, Quincy, Massachusetts, 1991.

Fischer, S., et al., “Vådautsläpp av brandfarliga och giftiga gaser och vätskor” (in Swedish),

FOA-D-95-00099-4.9-SE, Försvarets Forskningsanstalt Stockholm, 1995.

Harris , R.J., The Investigation and Control of Gas Explosions in Building and Heating Plant,

British Gas, 1983.

NFPA 921, “Fire and Explosion Investigations,” 1992 Edition, National Fire Protection Association,

Quincy, Massachusetts.

Senecal, J.A., “Explosion Prevention and Protection,” Section 4, Chapter 14, NFPA Fire Protection

Handbook, 18 Edition, National Fire Protection Association, Quincy, Massachusetts, 1997. th

Vervalin, C.H., Editor, Fire Protection Manual for Hydrocarbon Processing Plants, Volume 1,

3 Edition, Gulf Publishing Company, Houston, Taxes, 1985. rd

Zalosh, R.G., “Explosion Protection,” Section 3, Chapter 16, SFPE Handbook of Fire Protection

Engineering, 2 Edition, P.J. DiNenno, Editor-in-Chief, National Fire Protection Association, nd

Quincy, Massachusetts, 1995.

15.17 Additional Readings

Fardis, M.N., A. Nacar, and M.A. Delichatsios, “R/C Containment Safety Under Hydrogen Detonation,”

Journal of Structural Engineering, Volume 109, pp. 2511–2527, 1983.

Handbook of Chemical Hazard Analysis Procedures, Federal Emergency Management Agency

(FEMA), U.S. Department of Transportation (DOT), and U.S. Environmental Protection Agency

(EPA).

Lees, F.P., Loss Prevention in the Process Industries, Hazard Identification, Assessment and Control,

Volume, 1, Butterworths-Heinnemann, London and Boston, 1980.
15-18

15.18 Problems

Example Problem 15.18-1

Problem Statement

In an NPP, a liquid propane gas (LPG)-driven forklift is used to un load materials from an upcoming

outage. Mechanical failure could result in the release of LPG in the area. The maximum fuel

capacity of the forklift is 10 gallons. Calculate pressure rise, energy released by expanding LPG,

and equivalent TNT charge weight. Assume that the mass of the vapor released is 48 lb.

Solution

Purpose:

(1) Estimate pressure rise, energy released, and TNT equivalent.

Assumptions:

(1) The atmospheric pressure is 14.7 psi.

(2) Ambient air temperature is 77 °F.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 15_Explosion_Calculations.xls

FDT Input Parameters: s

-Select Fuel Type = Propane

-Percent yield = 100%

-Mass of flammable vapor release = 48 lb

Results*

Pressure Rise 528.6 kPa (76.7 psi)

Energy Released 1,011,491 kJ (957,983 Btu)

Equivalent TNT 225 kg (496 lb)

*see spreadsheet on next page
15-19

Spreadsheet Calculations

FDT : 15_Explosion_Calculations.xls s

CHAPTER 15. ESTIMATING PRESSURE INCREASE AND EXPLOSIVE ENERGY 

RELEASE ASSOCIATED IMTH EXPLOSIONS 

Version 1805.0 

The i:lllowing calculations estimae the pressure and energyd.Jeto an e:.plosion in a conined space. 

Parameters in YELLOW CELLS are Ertered bvthe User. 

Parameters in GREEN CELLS are ALicmaticallv SElected from the DROP DOWN M ENUforthe FueJ Selected . 

.All slbsequent Mp.R \Glues n calculated bythe spreadsheEt and based on Wues speci6!d n the inplt 

parameters. This spreadsheet is P'Ofe»ld and secure to 31.1cid urors due 10 a wrorg entryin a cells(s). 

The chapter in the NUR83 shodd be read befa"e 3'1 analysis is made. 

INPUT PARAMETERS 

EXPLOSIVE FUEL INFORMATION 

.A::Iiabalic Flame T Emperaure oflhe Fuel ((T «!) 

Hea of Corrbuslion oflhe Fuel (AH.) 

Yield (or.), i~t ., the taction ofMiable combl61ion 

1 percent fa' uroonfined mass release and 100 

percent i:lr conined 'Wporrelease energy 

panici~irg n bbstwaw genr.nion 

Mass ofFiarrmable \t.Jpcr ~lease (m) 

Anl)ent ~ Tempemure (T,.) 

Initial Pcmospheric Pressure (P,.) 

THERMAL PROPERTIES FOR FUELS 

FLAMMABILITY DATA FOR FUELS 

4638)~ I;.,~ 

100.00!-

14.10 <~ 

I caculae I 

I~LII C 

'"····•: 

ZI.SZI-:\1 

.soo·c 

Z\:$.00 ~ IOL)Sio:P~ 

Fu~ .A:Iiabatic Aame T errpemure Heat of Corrbustim Soded Fuel Type 

T •• (~) AH,(k.Jol<g) I ~aot ·I 

,., .. ~ .... 4179 48l20 Scroll to desired fuel t ypethE'fl 

Calbon Mmo:.ide 4329 10,100 Click on selection 

Bhane 2244 47,490 

Bhy»ne 4152 47,170 

~frtgen 4385 130~00 

ahane 2143 50030 

·BUI3ne 2442 46,720 

-Heptale 2586 44~60 

-Pentane 2356 44»80 

-Octane 2478 44.440 

Propane 2338 48~60 

Prop~ene 4350 46,790 

User SoeciMd \.taue 8"4Et ~ue Enter \t.ilue 1\~-~~IY.~: {'", :: , . « ,«;::1<\,o!< ·Ill '-. ::a " · 
15-20

METHOD OF ZALOSH Rnu~• o: : SfPE r.dOO&. VI ~ 'O i?\.1~ ~ t: l,:'i't>~t.: . 2'"' 5.1 'f. 1 ~~S. P~'i'3-3J 2. 

Pressure Rise from an Confine:! Explosion 

(P•,.,~YP~= (T ~n~) 

Where Ph\ = maximum pressure developed at completion of combustion (kP a) 

P~ = initial atmospheric pressure (kP a) 

r~· = adiabatic flame temperature (J-9 

r~ =ambient temperature (J-9 

P- = (T~1/T~ P~ 

IIPm.,= 

Blast Waw Energy Calculation 

E =ctlLHc mf 

528.57 kPa 76.66 psi 

Where E = blast wave energy(kJ) (E is the Trinitrotoluene (TN 1) equivalent energy] 

l:f.,(),l Ji 

a.= yield (ct is the fraction of available combustion energy participating in blast wave generation) 

lLHc = heat of combustion (kJA<g) 

mr = mass offlammable vapor release (kg) 

lie= 101149J.91 kJ 

TNT Mass Equiwlent Calculation 

W111T= E/4&10 

Where W111T= weight of TNT (kg) 

E = explosive energy release (kJ) 

224.78 kg 

957983.04 Btu 

495.551b 

The above calculations are based on principles developed in the SFPE H andbod< of Fire Protection 

Engineering, 21'01 Edition, 1995. 

Calculations are based on certain assumptions and have inherent limitations. The results of such 

calculations may or may not have reasonable predictive capabilities for a given situation. and should 

only be interpreted by an informed user. 

AHhough each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolubl guarantee of the accuracy of these calculations. 

Arfl/ questions, comments. concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or mxs3@nrc.gov. 

II hi !,I .I 

llh!Ji.l 
15-21

Example Problem 15.18-2

Problem Statement

An investigator is performing a review of an accident at a facility. The report states that a pipe fitter

accidently left his acetylene “B” tank on which leaked its contents and caused the explosion.

Assuming the tank was full (40 ft of gas at atmospheric pressure), how large could the explosion 3

have been?

Solution

Purpose:

(1) Estimate energy released, and TNT equivalent.

Assumptions:

(1) The atmospheric pressure is 14.7 psi.

(2) Ambient air temperature is 77 °F.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 15_Explosion_Calculations.xls

FDT Input Parameters: s

-Select Fuel Type = Acetylene

-Percent yield = 100%

-Mass of vapor release = volume x density (from manufacture’s Web site)

 40 ft x .0677 lb/ft = 2.7 lb 3 3

Results*

Energy Released 59,179 kJ (56,049 Btu)

Equivalent TNT 13.2 kg (29.0 lb)

*see spreadsheet on next page
15-22

Spreadsheet Calculations

FDT : 15_Explosion_Calculations.xls s

CHAPTER 15. ESTIMATING PRESSURE INCREASE AND EXPLOSIVE ENERGY 

RELEASE ASSOCIATED IMTH EXPLOSIONS 

Version 1805.0 

The i:lllowing calculations estimae the pressure and energyd.Jeto an e:.plosion in a conined space. 

Parameters in YELLOW CELLS are Ertered bvthe User. 

Parameters in GREEN CELLS are ALicmaticallv SElected from the DROP DOWN M ENUforthe FueJ Selected . 

.All slbsequent Mp.R \Glues n calculated bythe spreadsheEt and based on Wues speci6!d n the inplt 

parameters. This spreadsheet is P'Ofe»ld and secure to 31.1cid urors due 10 a wrorg entryin a cells(s). The chapter in the NUR83 shodd be read befa"e 3'1 analysis is made. 

INPUT PARAMETERS 

EXPLOSIVE FUEL INFORMATION 

.A::Iiabalic Flame T Emperaure oflhe Fuel ((T «!) 

Hea of Corrbuslion oflhe Fuel (AH.) 

Yield (or.), i~t ., the taction ofMiable combl61ion 

1 percent fa' uroonfined mass release and 100 

percent i:lr conined 'Wporrelease energy 

panici~irg n bbstwaw genr.nion 

Mass ofFiarrmable \t.Jpcr ~lease (m) 

Anl)ent ~ Tempemure (T,.) 

Initial Pcmospheric Pressure (P,.) 

THERMAL PROPERTIES FOR FUELS 

FLAMMABILITY DATA FOR FUELS 

Fu~ .A:Iiabatic Aame T errpem..re 

T •• ('l') 

48220 l;.,~ 

100.00!-

2.10 ~· 77.00 f 

14.10 <~ 

I caculae I 

Heat of Corrbustim Select Fuel Type 

AH,(k.Jol<g) I au~ lt!J 

1~)1-:\1 

.soo·c 

Z\:$.00 ~ IOL)Sio:P~ 

~ ,., .. ~ .... 4179 48~20 Scroll to desired fuel t ypethE'fl 

Calbon Mmoldde 4129 10,100 Click on selection 

Bhane 2244 47,490 

B~ne 4152 47,170 

Hy:lrogen 4185 130~00 

MEthane 2143 50030 

·BUI3ne 2442 46,720 

-~ptale 2586 44~60 

-Pentane 2356 44P80 

-Octane 2478 44.440 

Propane 2338 48~60 

Prop~ene 4150 46,790 

User ~eciMd \.taue 8"4« ~ue Enter~lue 

l\t1H~rw:t: = , ."-t.-wr«riM fll '- '" ::a cr, .vw.o. . ;:y:o ..... v . 
15-23

METHOD OF ZALOSH Rnu~• o: : SfPE r.dOO&. VI ~ 'O i?\.1~ ~ t: l,:'i't>~t.: . 2'"' 5.1 'f. 1 ~~S. P~'i'3-3J 2. 

Pressure Rise from an Confine:! Explosion 

(P•,.,~YP~= (T ~n~) 

Where Ph\ = maximum pressure developed at completion of combustion (kP a) 

P~ = initial atmospheric pressure (kP a) 

r~· = adiabatic flame temperature (J-9 

r~ =ambient temperature (J-9 

P- = (T~1/T~ P~ 

IIPm.,= 

Blast Waw Energy Calculation 

E =ctlLHc mf 

989.9) kPa 143.56 psi 

Where E = blast wave energy(kJ) (E is the Trinitrotoluene (TN 1) equivalent energy] 

l:f.,(),l Ji 

a.= yield (ct is the fraction of available combustion energy participating in blast wave generation) 

lLHc = heat of combustion (kJA<g) 

mr = mass offlammable vapor release (kg) 

lie= 59179.09 kJ 

TNT Mass Equiwlent Calculation 

W111T= E/4&10 

Where W111T= weight of TNT (kg) 

E = explosive energy release (kJ) 

13.15 kg 

56048.52 Btu 

28.991b 

The above calculations are based on principles developed in the SFPE H andbod< of Fire Protection 

Engineering, 21'01 Edition, 1995. 

Calculations are based on certain assumptions and have inherent limitations. The results of such 

calculations may or may not have reasonable predictive capabilities for a given situation. and should 

only be interpreted by an informed user. 

AHhough each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolubl guarantee of the accuracy of these calculations. 

Arfl/ questions, comments. concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or mxs3@nrc.gov. 

II hi !,I .I 

llh!Ji.l 
15-24

Example Problem 15.18-3

Problem Statement

Which has a larger TNT mass equivalent: 10 lb (mass vapor) of acetylene or 5 lb (mass vapor)

of hydrogen?

Solution

Purpose:

(1) Estimate TNT equivalent.

Assumptions:

(1) The atmospheric pressure is 14.7 psi.

(2) Ambient air temperature is 77 °F.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 15_Explosion_Calculations.xls

FDT Input Parameters: s

-Select Fuel Type = Acetylene

-Percent yield = 100%

-Mass of flammable vapor release = 10 lb

-Select Fuel Type = Hydrogen

-Percent yield = 100%

-Mass of flammable vapor release = 5 lb

Results*

Acetylene Hydrogen

Equivalent TNT 48.7 kg (107 lb) 66.0 kg (146 lb)

*see spreadsheet on next page

Therefore, 5 lb of hydrogen produces more explosive force than 10 lb of acetylene.
15-25

Spreadsheet Calculations

(a) FDT : 15_Explosion_Calculations.xls (Acetylene) s

CHAPTER 15. ESTIMATING PRESSURE INCREASE AND EXPLOSIVE ENERGY 

RELEASE ASSOCIATED IMTH EXPLOSIONS 

Version 1805.0 

The i:lllowing calcolalions eslimae the pressure and energydJeto an e:-plosion in a conined space. 

Parameters in YELLOW CELLS are Ertered bvthe User. 

Parameters in GREEN CELLS are ALtcmaticallv Selecb!dfromthe DROP DOWN M ENUforthe Fuel Selected. 

All slbsequent rutp.Jl \Glues n calculated bythe spreadsheEt and based on values specified n the inplt 

para~"Mters. This spreadsheet is P'Of~d and securew 31.1cid errors due to a wrorg entryin a oells(s). 

The chapter in the NUR83 shodd be read befa"e 3'1 analy;is is made. 

INPUT PARAMETERS 

EXPLOSIVE FUEL INFORMATION 

.Adiabatic Flame T Emperaure oflhe Fuel ((T ,.!) 

Hea of Corrbustion oflhe Fuel (AH.) 

Yield (or.), i.e., the faction of Mlable comblG!ion 

1 percent fu' uroonfined mass release and 100 

percent i:lr conined \Gporrele:ase energy 

participatirg il bbstwaw genDon 

Mass ofFiarrmable \1.3pcr Release (m) 

.Anbent ~ Temper.rrure (T ,.) 

Initial P4mospheric Pressure (P,.) 

THERMAL PROPERTIES FOR FUELS 

FLAMMABILITY DATA FOR FUELS 

Fu~ .A:Iiabatic Aame T errpemure 

T •• (~) 

48220 l;., 

100.00!-

10.00 ~" 77.00 f 

14.70 <~ 

I Calculcte I 

Heat of Corrbustim Soded Fuel Type 

AH,(k.Jol<g) I ~U.Iill 

+.»t:\1 

.s.oo·c 

Z\:$.00 ~ 

101.351-:P~ 

·I 

,., .. ~ .... 4179 48l20 Scroll to desired fuel t ypethE'fl 

Calbon Mmo:.ide 4329 10,100 Click on selection 

Bhane 2244 47,490 

Bhy»ne 4152 47,170 

~frtgen 4385 130~00 

ahane 2143 50030 

·BUI3ne 2442 46,720 

-Heptale 2586 44~60 

-Pentane 2356 44»80 

-Octane 2478 44.440 

Propane 2338 48~60 

Prop~ene 4350 46,790 

User SoeciMd \.taue 8"4Et ~ue Enter \t.ilue 1\~-~~IY.~: {'", :: , . « ,«;::1<\,o!< ·Ill '-. ::a " · 
15-26

METHOD OF ZALOSH Rnu~• o: : SfPE r.dOO&. VI ~ 'O i?\.1~ ~ t: l,:'i't>~t.: . 2'"' 5.1 'f. 1 ~~S. P~'i'3-3J 2. 

Pressure Rise from an Confine:! Explosion 

(P•,.,~YP~= (T ~n~) 

Where Ph\ = maximum pressure developed at completion of combustion (kP a) 

P~ = initial atmospheric pressure (kP a) 

r~· = adiabatic flame temperature (J-9 

r~ =ambient temperature (J-9 

P- = (T~1/T~ P~ 

IIPm.,= 

Blast Waw Energy Calculation 

E =ctlLHc mf 

989.9) kPa 143.56 psi 

Where E = blast wave energy(kJ) (E is the Trinitrotoluene (TN 1) equivalent energy] 

l:f.,(),l Ji 

a.= yield (ct is the fraction of available combustion energy participating in blast wave generation) 

lLHc = heat of combustion (kJA<g) 

mr = mass offlammable vapor release (kg) 

lie= 219181.82 kJ 

TNT Mass Equiwlent Calculation 

W111T= E/4&10 

Where W111T= weight of TNT (kg) 

E = explosive energy release (kJ) 

48.71 kg 

207587.10 Btu 

107.381b 

The above calculations are based on principles developed in the SFPE H andbod< of Fire Protection 

Engineering, 21'01 Edition, 1995. 

Calculations are based on certain assumptions and have inherent limitations. The results of such 

calculations may or may not have reasonable predictive capabilities for a given situation. and should 

only be interpreted by an informed user. 

AHhough each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolubl guarantee of the accuracy of these calculations. 

Arfl/ questions, comments. concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or mxs3@nrc.gov. 

II hi !,I .I 

llh!Ji.l 
15-27

(B) FDT : 15_Explosion_Calculations.xls (Hydrogen) s

CHAPTER 15. ESTIMATING PRESSURE INCREASE AND EXPLOSIVE ENERGY 

RELEASE ASSOCIATED IMTH EXPLOSIONS 

Version 1805.0 

The i:lllowing calculations estimae the pressure and energyd.Jeto an e:.plosion in a conined space. 

Parameters in YELLOW CELLS are Ertered bvthe User. 

Parameters in GREEN CELLS are ALicmaticallv SElected from the DROP DOWN M ENUforthe FueJ Selected . 

.All slbsequent Mp.R \Glues n calculated bythe spreadsheEt and based on Wues speci6!d n the inplt 

parameters. This spreadsheet is P'Ofe»ld and secure to 31.1cid urors due 10 a wrorg entryin a cells(s). The chapter in the NUR83 shodd be read befa"e 3'1 analysis is made. 

INPUT PARAMETERS 

EXPLOSIVE FUEL INFORMATION 

.A::Iiabalic Flame T Emperaure oflhe Fuel ((T «!) 

Hea of Corrbuslion oflhe Fuel (AH.) 

Yield (or.), i~t ., the taction ofMiable combl61ion 

1 percent fa' uroonfined mass release and 100 

percent i:lr conined 'Wporrelease energy 

panici~irg n bbstwaw genr.nion 

Mass ofFiarrmable \t.Jpcr ~lease (m) 

Anl)ent ~ Tempemure (T,.) 

Initial Pcmospheric Pressure (P,.) 

THERMAL PROPERTIES FOR FUELS 

FLAMMABILITY DATA FOR FUELS 

Fu~ .A:Iiabatic Aame T errpem..re 

T •• ('l') 

130800 l;.,~ 

100.00!-

5.00 ~· 77.00 f 

14.10 <~ 

I caculae I 

Heat of Corrbustim Select Fuel Type 

AH,(k.Jol<g) Ud!!UI9Hl 

.soo·c 

Z\:$.00 ~ IOL)Sio:P~ 

~ ,., .. ~ .... 4179 48~20 Scroll to desired fuel t ypethE'fl 

Calbon Mmoldde 4129 10,100 Click on selection 

Bhane 2244 47,490 

B~ne 4152 47,170 

Hy:lrogen 4185 130~00 

MEthane 2143 50030 

·BUI3ne 2442 46,720 -~ptale 2586 44~60 

-Pentane 2356 44P80 

-Octane 2478 44.440 

Propane 2338 48~60 

Prop~ene 4150 46,790 

User ~eciMd \.taue 8"4« ~ue Enter~lue 

l\t1H~rw:t: = , ."-t.-wr«riM fll '- '" ::a cr, .vw.o. . ;:y:o ..... v . 
15-28

METHOD OF ZALOSH Rnu~• o: : SfPE r.dOO&. VI ~ 'O i?\.1~ ~ t: l,:'i't>~t.: . 2'"' 5.1 'f. 1 ~~S. P~'i'3-3J 2. 

Pressure Rise from an Confine:! Explosion 

(P•,.,~YP~= (T ~n~) 

Where Ph\ = maximum pressure developed at completion of combustion (kP a) 

P~ = initial atmospheric pressure (kP a) 

r~· = adiabatic flame temperature (J-9 

r~ =ambient temperature (J-9 

P- = (T~1/T~ P~ 

IIPm.,= 

Blast Waw Energy Calculation 

E =ctlLHc mf 

8$.67 kPa 124.54 psi 

Where E = blast wave energy(kJ) (E is the Trinitrotoluene (TN 1) equivalent energy] 

l:f.,(),l Ji 

a.= yield (ct is the fraction of available combustion energy participating in blast wave generation) 

lLHc = heat of combustion (kJA<g) 

mr = mass offlammable vapor release (kg) 

lie= 2S7272.73 kJ 

TNT Mass Equiwlent Calculation 

W111T= E/4&10 

Where W111T= weight of TNT (kg) 

E = explosive energy release (kJ) 

66.03 kg 

281547.00 Btu 

145.641b 

The above calculations are based on principles developed in the SFPE H andbod< of Fire Protection 

Engineering, 21'01 Edition, 1995. 

Calculations are based on certain assumptions and have inherent limitations. The results of such 

calculations may or may not have reasonable predictive capabilities for a given situation. and should 

only be interpreted by an informed user. 

AHhough each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolubl guarantee of the accuracy of these calculations. 

Arfl/ questions, comments. concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or mxs3@nrc.gov. 

II hi !,I .I 

llh!Ji.l 
16-1

CHAPTER 16. CALCULATING THE RATE

OF HYDROGEN GAS GENERATION IN BATTERY ROOMS

16.1 Objectives

This chapter has the following objectives:

• Explain how hydrogen gas is generated in a battery room.

• Describe the conditions under which hydrogen gas will ignite.

• Describe possible ignition sources in a battery room.

• Explain methods of controlling the combustion of hydrogen gas.

• Describe how to estimate hydrogen gas generation rates.

16.2 Introduction

Battery rooms in nuclear power plants (NPPs) represent a potential problem area because of the

generation of hydrogen gas. An NPP is typically equipped with large banks of 250-V dc and 125-V

dc battery systems (NUREG/CR-2726). The 250-V dc system consists of two banks of 120 leadcalcium (lead-acid) storage cells, and the 125-V dc system typically contains four banks of 60 cells.

Each bank is mounted in two rows of battery racks and located in its own battery room.

During operation, as the batteries change chemical energy to electrical energy, the sulfuric acid

content of the electrolyte becomes depleted. Therefore, the batteries must be recharged if they are

to be used continuously. This is done by connecting a dc charging source that enables current to

flow through the battery in the direction opposite of its normal flow, thereby driving the acid back

into the electrolyte. However, the byproducts of this charging process, or electrolysis, can present

a safety issue. As a cell becomes nearly charged, the charging current becomes greater than that

necessary to force the remaining amount of sulfuric acid back into the electrolyte. This results in

ionization of the water in the electrolyte liberates hydrogen gas at the positive plate. The maximum

rate of formation is 0.42 x 10 m (0.42 liter) of hydrogen and 0.21 x 10 m (0.21 liter) of oxygen -3 3 -3 3

per ampere-hour overcharge at standard temperature and pressure. The gas mixture is explosive

when the hydrogen concentration in air exceeds 4.1-percent by volume.

Although the release of this gas is undesirable, the process is necessary to develop a full charge

in the cell. Consequently, NPPs must take precautions to prevent explosions from ignition of the

flammable gas mixture of hydrogen and oxygen formed during overcharging of lead-acid cells.

NPPs employ several methods to reduce the risk associated with high hydrogen concentrations.

Regardless of the method used, proper implementation requires an accurate measurement of the

hydrogen concentration. A variety of hydrogen detectors are available for use in NPPs. A standard

practice is to set hydrogen detection devices to activate at 2.0–2.5-percent by volume of the lower

explosive limit (LEL).
16-2

16.3 Combustion of Hydrogen Gas

Hydrogen gas has an extremely wide flammability range and the highest burning velocity of any

gas. Its ignition temperature is reasonably high [500 °C (932 °F)], but its ignition energy is very low.

Because hydrogen contains no carbon, it burns with a nonluminous flame, which is often invisible

15 in daylight. At ordinary temperatures, hydrogen is very light, weighing only about ' as much as air. 1

Combustion of hydrogen according to the reaction—

2H2 2 2 + O ----------> 2H O + Energy (heat)

results in a release of about 57.8 kcal/g-mole (5.2 x 10 Btu/lb-mole) of hydrogen burned 4

(NUREG/CR-6042). For a flammable gas mixture, the flammability limits are defined as the limiting

concentrations of fuel, at a given temperature and pressure, in which a flame can propagate

indefinitely. Limits for upward propagation of flames are wider than those for downward

propagation. Limits for horizontal propagation are between those for upward and downward

propagation.

The lower flammability limit (LFL) is the minimum concentration of hydrogen required to propagate

a flame, while the upper flammability limit (UFL) is the maximum concentration. At the LFL, the

hydrogen is in short supply and the oxygen (air) is present in excess. At the UFL for hydrogen in

air, the oxygen (air) is in short supply, about 5-percent oxygen by volume. In air at standard

temperature and pressure (25 °C, 1 atm), and 100-percent relative humidity, the LFL for hydrogen

combustion is 4.1-percent hydrogen concentration by volume. Table 16-1 indicates the

approximate hydrogen concentrations required for combustibility in air (NUREG/CR-6042).

Table 16-1. Hydrogen Flammability Limits in Air at Room Temperature

Possible Reaction Lower Flammability Limit

Volume Percent of Hydrogen

Upper Flammability Limit

Volume Percent of Hydrogen

Upward propagation 4.1 74

Horizontal propagation 6.0 74

Downward propagation 9.0 74

Figure 16-1 shows the flammability limits of hydrogen with the addition of excess carbon dioxide

and nitrogen (diluents). Note that with 75-percent additional nitrogen, the atmosphere is inert. This

corresponds to 5-percent oxygen at the limit of the flammable region, a value very close to that of

the UFL for hydrogen air combustion. Similarly, the atmosphere is inert when the carbon dioxide

concentration is 60-percent or above, corresponding to 8-percent oxygen or less. The larger

specific heat of carbon dioxide reduces the flame temperature and flame velocity; hence, carbon

dioxide suppresses flammability more than nitrogen. By contrast, it requires about 60-percent

steam to inert a hydrogen-air-steam mixture. Figure 16-2 indicates the regions of flammability of

hydrogen-air-steam mixtures (Shapiro and Moffette, 1957).
16-3

Figure 16-1 Flammability Limits of Hydrogen in Air Diluted with Carbon Dioxide

and Nitrogen (Shapiro and Moffette, 1957)

Figure 16-2 Flammability Limits of Hydrogen in Air-Steam Mixtures

(Shapiro and Moffette, 1957)
16-4

16.4 Ignition of Hydrogen Gas

Accidental ignition of hydrogen could be caused by several sources in a structure if the hydrogen

concentration in air were to reach sufficient levels. Ignition of dry hydrogen-air mixtures, particularly

when the mixtures are well within the flammability limits, can occur with a very small input of energy

(Shapiro and Moffette, 1957). Common sources of ignition are sparks from electrical equipment

and the discharge of small static electric charges. In fact, the minimum energy required from a

spark for ignition of a quiescent hydrogen air mixture is on the order of 10 J (10 Btu)—a very -4 -7

weak spark. Figure 16-3 (Drell and Belles, 1958) shows the ignition energy required as a function

of hydrogen concentration. For a flammable mixture, the required ignition energy increases as the

hydrogen concentration approaches the flammability limits. The addition of a diluent, such as

steam, substantially increases the required ignition energy.

Figure 16-3 Spark Ignition Energies for Dry Hydrogen-Air Mixtures

(Drell and Belles, 1958)
16-5

16.4.1 Battery as an Ignition Source

Given the discussion in the previous section, it is relatively easy to accept the fact that a battery can

act as an ignition source for the hydrogen-air mixture that results from its own charging process.

Since all functional vented batteries generate a stoichiometric mixture of hydrogen and oxygen

gases during overcharging and expel them normally from the cell into the battery container, a

potential always exists that these gases may explode. Normally, the battery case does not contain

any ignition sources, but several abnormal possibilities do exist. One is the internal short-circuiting

of a relatively dry cell in overcharging, resulting in an explosion inside the cell with a subsequent

ejection of flames into the battery case. A second and more likely source of ignition may exist at

an improperly maintained cell terminal, as a result of the high temperatures generated during highrate discharge. A third source of ignition may occur at the site of stray leakage currents.

16.4.2 Control of Hydrogen Gas Combustion

An NPP can effectively control a flammable gas-oxidant mixture by reducing the concentration of

oxidant or by adding an inert constituent to the mixture. Both processes can be explained most

easily by referring to a flammability diagram. Figure 16-4 (NFPA 69, 1997 Edition) for example,

shows a typical flammability diagram representing a mixture of combustible gas, an inert gas,

(nitrogen), and an oxidant, (oxygen), at a given temperature and pressure. A mixture of air

2 2 (79-percent N and 21-percent O , by volume) and combustible gas is represented by line DABE.

A given mixture of combustible gas and air, whether ignitable or not, is specified by some point on

this line. Point A indicates the UFL of this mixture, while point B represents its LFL. Point C

represents the limiting oxidant concentration to prevent ignition; any mixture containing less oxygen

cannot be ignited. Any point within the area bounded by curve FBCAG is in the flammable range

and can be ignited. Any mixture of oxygen and combustible gas alone (i.e., without any nitrogen)

is represented by the left-hand side of the triangle. Any mixture of nitrogen and combustible gas

alone (i.e., no oxygen present) is represented by the right-hand side of the triangle.

Figure 16-4 Typical Flammability Diagram

(NFPA 69, 1997 Edition, © NFPA. With permission.)
16-6

NPPs rely on several simple (but extremely important) methods to prevent hydrogen combustion

in battery rooms. First, the rooms are well-ventilated to prevent excessive hydrogen buildup.

The battery room ventilation system in NPPs typically limits hydrogen concentration to less than

2 percent of the total volume of the room and maintains a constant temperature of 25 °C (77 °F).

The air flow rate is approximately 10 air changes per hour. As an additional precaution, no open

flame or smoking is allowed in the proximity of the battery room. Also, any work in the room must

be performed with non-sparking tools made of brass, aluminum, or wood (Linden, 1994).

To date, there have been no major accidents involving hydrogen gas in the battery rooms at NPPs

(NUREG/CR-2726). However, in other (non-nuclear) industries, there have been instances of

hydrogen explosions reported in battery charging areas ranging in size from submarine battery

rooms to uninterruptible power supply (UPS) battery rooms where batteries create a real problem

during periods of high recharge.

On March 20, 2001, a hydrogen explosion occurred in the UPS/battery room of a large computer

data center in Sacramento, California (“Explosion in Rancho Cordova,” 2001). The explosion blew

a 400+ ft hole in the roof, collapsed numerous walls and ceilings throughout the data center, and 2

significantly damaged a large portion of the 50,000 ft building. 2

16.5 Fire Protection Code Requirements for Battery Rooms

Regarding battery room fire protection for NPPs, Regulatory Guide (RG) 1.189 states that battery

rooms should be separated from each other and other areas of the plant by barriers having a

minimum fire rating of 3 hours, inclusive of all penetrations and openings. RG 1.189 also states

that ignition sources (such as the DC switchgear room and inverters should not be located in

batteries rooms. In addition, RG 1.189 recommends that automatic fire detection should be

provided to alarm and annunciate in the control room and alarm locally. Ventilation systems in the

battery rooms should also be capable of maintaining the hydrogen gas concentration well below

2 percent. Loss of ventilation should be alarmed in the control room and standpipe, and a hose

station and portable fire extinguishers should be readily available outside the room.

Similar to RG 1.189, Section E2.12 of NFPA 805, “Performance-Based Standard for Fire Protection

for Light Water Reactor Electric Generating Plants,” 2001 Edition recommends that battery rooms

should be separated from adjacent areas by fire-rated barriers. It also recommends that battery

rooms should be ventilated to limit the concentration of hydrogen gas to 1-percent by volume in

accordance with NFPA 69, “Standard on Explosion Prevention Systems.” In addition, NFPA 805

requires that direct current switchgear and inverters should not be located in battery rooms. For

detailed information, refer to IEEE-484, “Recommended Practice for Installation Design and

Installation of Vented Lead-Acid Batteries for Stationary Applications.”

In similar fashion, Section 8.7 of NFPA 804, “Standard for Fire Protection for Advanced Light Water

Reactor Electric Generating Plants,” 2001 Edition recommends that battery rooms should be

protected against fires and explosion, and that ventilation should be provided to limit the

concentration of hydrogen to 2-percent by volume. It also recommends that battery rooms should

be separated from other areas of the plant by fire barriers having a 1-hour minimum rating and

direct current switchgear and inverters should not be located in battery rooms.
16-7

Finally, Section 3-4 of NFPA 801, “Standard for Fire Protection for Facilities Handling Radioactive

Materials,” 2003 Edition, provides additional guidance for battery rooms, stating that “the facility

shall be subdivided into separate fire areas as determined by the fire hazards analysis for the

purpose of limiting the spread of fire, protecting personnel, and limiting the consequential damage

to the facility. Fire areas shall be separated from each other by barriers with fire resistance

commensurate with the potential fire severity. ” Specifically, Section A-3-4 of NFPA 801

recommends that battery rooms should be separated by fire barriers having a 3-hour minimum

rating. It also recommends that electrical equipment, such as the switchgear and relay rooms

should be located in separate fire areas.

NFPA 70E, “Standard for Electrical Safety Requirements for Employee Workshops,” 2000 Edition

contains additional requirements for vented-type batteries, which require ventilation to limit

hydrogen gas concentration exceeding 1-percent by volume. Similar requirements exist for valveregulated lead-acid (VRLA) storage batteries.

16.6 Method of Calculating the Rate of Hydrogen Generation in Battery Rooms

As previously explained, hydrogen gas is primarily generated in battery rooms as a result of battery

overcharge. The generation of hydrogen is particularly important because of its rapid production

rate and high flammability. A hydrogen-rich environment could accumulate in a battery room if the

ventilation flow through the space is completely stopped or other events allow hydrogen

accumulation. The formation of flammable fuel (hydrogen)/oxidant mixtures within a battery room

can lead to premixed flame propagation in the form of fire and explosion events, which can cause

failure of the structures, ventilation systems, power systems, and monitoring systems. A significant

amount of hydrogen gas is liberated only when the battery approaches full charge. The maximum

hydrogen evolution rate is 7.56 x 10 m (0.000267 ft ) per minute per charging ampere per cell -6 3 3

at 25 °C (77 °F) and 1-atmosphere (Yuasa, Inc., 2000).

The method to calculate the amount of hydrogen produced from batteries in an enclosure is

excerpted from the appendix to Section 58.00 of the Yuasa Catalog (2000). This method considers

an antimony alloy-type (flat plate, tubular, or Manchex) battery at a point where it is nearing its end

of life, or equalizing charge at 2.33 VPC (volts per cell).

The rate of hydrogen generation from a battery can be approximated using the following equation

(Yuasa, Inc., 2000):

 (16-1)

Where:

Hgen = hydrogen gas generation, ft /min 3

FC H = float current per 100 A (temperature compensated) in milliamperes

AH = ampere hours (nominal 8 hour)

K H = constant - 1 A = 0.000267 ft3

N = number of cells
16-8

Table 16 C-2 summarizes the float current (F ) demand of fully charged stationary lead-acid cells.

Table 16-2. Float Current Demand for a Stationary Battery

Charge Voltage

(VPC)

F Cloat Current (F ) milliamperes per 100 AH @ 8-hour rate

Antimony Calcium

New Old

2.15 15 60 -

2.17 19 80 4

2.20 26 105 6

2.23 37 150 8

2.25 45 185 11

2.27 60 230 12

2.33 120 450 24

2.37 195 700 38

2.41 300 1,100 58

Note: The above values apply when the electrolyte temperature is 25 °C (77 °F). The values double for every 8 °C

(15 °F) of temperature rise. If the temperature drops, the current value is halved for every 8 °C (15 °F) decrease.

Antimony ranges indicate current increases attributable to cell aging.

16.7 Method of Calculating Flammable Gas and Vapor Concentration Buildup

in Enclosed Spaces

The minimum and maximum concentration of combustible material in a homogeneous mixture with

a gaseous oxidizer that will propagate a flame is called flammable limits. Upper and lower

flammability limits represent the range of concentrations of fuel in air in which a premixed flame

can propagate.

A deflagration is possible if the concentration of a gas rises above its LFL. A detonation can occur

if the velocity of a propagation of a combustion zone is greater than the speed of sound in the

unreacted medium. For a detonation pressure rises are estimated as 2 to 4 times that of a

deflagration. Deflagrations are characterized by slow subsonic propagation of a flame front, and

slow but uniform rise in the pressure and temperature of the gas by the heat released from the

combustion.
16-9

A detonation produces a shock wave driven and sustained by the chemical energy released from

the chemical reaction. The shock wave and the reaction propagate together in the unburned gas

at a speed which exceeds that of sound in the unburned medium, i.e., of the order of 1,500 to 2,000

m/sec (Fardis et al., 1983). The shock front is characterized by an abrupt increase in pressure,

temperature, and density of the gas, and by the net forward movement of the gas particles. Shock

reflection produces a large pressure on the wall (e.g., 2 to 4 times the incident pressures for a

deflagration), and generates a purely mechanical wave which propagates inward in the already

burnt gas until interacts with another wave produced by the reflection elsewhere.

The volume gas or vapor for deflagration is give by the following expression:

 (16-2)

Where:

Vdef = volume of gas vapor for deflagration (ft )

3

V = volume of the enclosure (ft )

3

LFL = lower flammability of gas or vapor (percent-volume)

16.8 Method of Calculating Flammable Gas and Vapor Concentration Buildup Time

in Enclosed Spaces

NFPA 69, “Standard on Explosion Prevention Systems,” provides a method to calculate the time

to buildup of combustible concentration of a flammable gas in enclosed area.

If a constant source of flammable gas is introduced into an enclosed volume, the buildup of

flammable gas concentration is given by the following equation:

 (16-3)

Where:

C = gas concentration by volume

G = flammable/combustible gas discharge rate (ft /min) 3

Q = volume of air in enclosure (ft /min) 3

K = mixing efficiency factor (constant)

N = number of theoretical air changes

Equation (16-3) can be rewritten into a more convenient logarithmic form:

 (16-4)

In perfect conditions, K = 1.0, Table 16-3 lists mixing efficiency factor (K) for certain conditions.
16-10

Table 16-3. Mixing Efficiency for Various Ventilation Arrangements

Method of Supplying Efficiency K Values

Single Exhaust

Opening

Multiple Exhaust

Opening

No Positive Supply

Infiltration through cracks 0.2 0.3

open doors, or windows 0.2 0.4

Forced Air Supply

Grills and registers 0.3 0.5

Diffusers 0.5 0.7

Perforated ceiling 0.8 0.9

16.9 Assumptions and Limitations

The methods discussed in this chapter are subject to several assumptions and limitations:

(1) Hydrogen gas is primarily generated in battery rooms as a result of battery overcharge.

(2) The generation of hydrogen environment could occur if the ventilation flow through the

vapor space is completely stopped or other events allow hydrogen accumulation.

(3) This method assumes that significant amounts of hydrogen gas are liberated only when the

battery approaches full charge.

(4) The calculations will produce a first order approximation.

(5) The battery hydrogen generation equation is based on one specific vendor’s

recommendations.

16.10 Required Input for Spreadsheet Calculations

The user must obtain the following data before attempting a calculation with the spreadsheet:

(1) charge voltage (vpc)

(2) ampere Hours

(3) number of cells
16-11

16.11 Cautions

(1) Make sure to input data in the correct units.

(2) Use spreadsheet (16_Battery_Room_Flammable_Gas_Conc.xls) on the CD-ROM

for calculations.

16.12 Summary

(1) Adequate ventilation is the most common form of fire prevention/protection in battery rooms.

Ventilation must be adequate to prevent hydrogen gas from exceeding a concentration of

2 percent by volume, and to ensure that pockets of trapped hydrogen gas do not develop

(particularly at the ceiling).

(2) The exhaust air outlets from the battery room shall be located separately so that a

hazardous concentration of the exhausted air cannot enter or be drawn into the fresh air

intakes of environmental air handling systems.

(3) Building and fire codes require spill containment systems for battery installations that

contain electrolyte.

(4) NPP should maintain an ambient temperature of 23 to 26 °C (72 to 78 °F) in battery rooms.

2

(5) To extinguish a fire in a battery room containing lead-acid batteries, use CO , fire protection

foam, or dry chemical extinguishing media. Do not discharge the extinguisher directly onto

the battery. The resulting thermal shock may cause cracking of the battery case and/or

cover.

(6) In case of fire, the power should be shut off if batteries are on charge. Use a positivepressure, self-contained breathing apparatus. Remember that water applied to an

electrolyte generates heat and causes it to splatter. Wear acid-resistant clothing.
16-12

16.13 References

Drell, I.L., and F.E. Belles, “Survey of Hydrogen Combustion Properties,” Technical Note NACA R

1383, National Advisory Committee for Aeronautics (NACA), Washington, DC, 1958.

“Explosion in Rancho Cordova,” Press Release, Sacramento Metropolitan Fire District, March 20,

2001, available at http://www.smfd.ca.gov.

Fardis, M.N., A. Nacar, and M.A. Delichatsios, “R/C Containment Safety Under Hydrogen

Detonation,” Journal of Structural Engineering, Volume 109, pp. 2511–2527, 1983.

IEEE-484, “Recommended Practice for Installation Design and Installation of Vented Lead-Acid

Batteries for Stationary Applications,” The Institute of Electrical and Electronics Engineers,

New York.

Linden, D., Editor-in-Chief, Handbook of Batteries, 2 Edition, McGraw-Hill, Inc., New York, 1994. nd

NFPA 69, “Standard on Explosion Prevention Systems,” 1997 Edition, National Fire Protection

Association, Quincy, Massachusetts.

NFPA 70E, “Standard for Electrical Safety Requirements for Employee Workplaces,” 2000 Edition,

National Fire Protection Association, Quincy, Massachusetts.

NFPA 801, “Standard for Fire Protection for Facilities Handling Radioactive Materials,” 1998

Edition, National Fire Protection Association, Quincy, Massachusetts.

NFPA 804, “Standard for Fire Protection for Advanced Light Water Reactor Electric Generating

Plants,” 2001 Edition, National Fire Protection Association, Quincy, Massachusetts.

NFPA 805, “Performance-Based Standard for Fire Protection for Light Water Reactor Electric

Generating Plants,” 2001 Edition, National Fire Protection Association, Quincy, Massachusetts.

Nuclear Regulatory Commission (U.S.), NUREG/CR-2726, “Light-Water Reactor Hydrogen

Manual.” NRC: Washington, D.C. August 1983.

Nuclear Regulatory Commission (U.S.), NUREG/CR-6042, Rev. 2, “Perspective on Reactor Safety,”

NRC Washington, DC, March 2002.

Nuclear Regulatory Commission (U.S.), Regulatory Guide 1.189, “Fire Protection for Operating

Nuclear Power Plants,” NRC Washington, DC, April 2001.

Shaprio, Z.M., and T.R. Moffette, “Hydrogen Flammability Data and Application to PWR Loss-ofCoolant Accident,” WAPD-SC-545, Bettis Plant, September 1957.

Yuasa, Inc., Safety Storage, Installation, Operation, and Maintenance Manual, Section 58.00,

Heritage Series, Flooded Lead-Acid Batteries, 2000. TM
16-13

16.14 Problems

Example Problem 16.14-1

Problem Statement

Assume a 60-cell GT-41 (3,730 Ampere-hour) battery near the end of its life, on equalize

at 2.33 VPC at an electrolyte temperature of 92 °F (33 °C). Estimate the rate of hydrogen

generation (in cubic feet per minute).

Solution

Purpose:

(1) Estimate the rate of hydrogen generation.

Assumptions:

(1) Old Antimony-type battery

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 16_Battery_Room_Flammable_Gas_Conc.xls

 (click on Battery_Room_Hydrogen)

FDT Input Parameters: s

-Ampere Hours = 3730 Ah

-Number of Cells = 60

-Click on Old Antimony type and Select 2.33 VPC

Results*

Generation Rate 0.538 ft /m (0.0152 m /min) 3 3

*see spreadsheet on next page
16-14

Spreadsheet Calculations

FDT : 16_Battery_Room_Flammable _Gas_Conc.xls (Battery_Room_Hydrogen) s

CHAPlER 16. CALCU LATIIIG THE RATE OF HYDR OGEII GAS GEIIERATIOII 

Ill BATTERY ROOMS 

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16-15

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16-16

Example Problem 16-2

Problem Statement

Consider an enclosure (10ft wide x 10ft long x 10ft high) 1,000 ft (28 m ) in turbine generator area 3 3

of a nuclear facility in which hydrogen gas is accumulated. Calculate the concentration of hydrogen

gas by volume reaching its LFL of 4 percent.

Solution

Purpose:

(1) Estimate the concentration of hydrogen gas in the compartment at LFL.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 16_Battery_Room_Flammable _Gas_Conc.xls

 (click on Flammable_Gas_Buildup)

FDT Input Parameters: s

c

-Compartment Width (w ) = 10 ft

c

-Compartment Length (l ) = 10 ft

c

-Compartment Height (h ) = 10 ft

-Select Hydrogen

Results*

Volume 40 ft (1.13 m )

3 3

*see spreadsheet on next page

Therefore, the concentration of hydrogen gas in the 1000 ft compartment is 4% (40/1000). 3
16-17

Spreadsheet Calculations

FDT : 16_Battery_Room_Flammable _Gas_Conc.xls (Flammable_Gas_Buildup) s

CHAPTER 1G. CALCULATING THE RATE OF HYDROGEN GAS GENERATION 

IN BATTERY ROOMS 

Version 1805.0 

The follcwing calculations estimate the flammable concentration of gases and vapors in enclosures. 

PcramSers in YELLOW CELLS are Enta-e::l bvthe User. 

PcramSers in GREEN CELLS ere Automcticallv Selededfromthe DROP DOWN MENU fort he Gas or 'vapor Selected. 

All subsequent output values are calcula~d by the spreadsheet and based on values specified in the input 

parameters. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a cel(s). 

The chap~r in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

Lo~r Flammabilio/ Umit of Flammable Gas or Vapor (LFt.;l 4.00 Percent 

Compartment Width (lilt) 10.00 ft 

Compartment Length (l,) 10.00 ft 

Compartment Height(h.) 10.00 ft 

Calculare 

LOIM:R FLAMMABILITY DATA FOR GASES AND VAPORS 

Gases and LFL re;:or \@?or 3 

Vapors Volume- Percent 

Stroll to desire:! gas o r 'JCIPOr thS'l Oit k on selecticn 

Hydrogen 4.00 

Carbon Monoxide 12.50 

Methane 5.00 

Ethane 3.00 

Propane 2.10 

n- Butane 1.80 

n- Pentdne 1.4J 

n- Hexane 1.20 

n- Heptane 1.05 

n- Octane 0.95 

n- Nonane 0.85 

n- De cane 0.75 

Ethene 2.70 

Propane 2.4J 

Bu~ne-1 1.70 

Ace~lene 2.50 

Methanol 6.70 

Ethanol 3.3J 

n- Propanol 2.20 

Acetone 2.eo 

Methyl Ethyl Ketone 1.80 

Diethyll<done 1.eo 

Benzene 1.3J 

User Specified Value Enter Value 

• . . . . ~ . .... . ' ~ 

0.040 
16-18

E SnMATIIIG FLAivlvWILE COIICEIIlRATIOII OF GASES USIIIG LIIYITS OF FLAivlvWIIUTY 

\A:IIume of Gas or \4por i:lr Oeiag1'31ion = Vx LFL 

VlJhere V= \Oiume oferolosure (ft:t) 

LFL = lower 1arrmability of a gas or \Gpor (percent· \Oiume) 

Vdune d Ccmp<rimert 

V= u.k x k xh~ 

Where 

V= 

V= compatment vdume (ft) 

w .. = ccmparment width (ft) 

k = compatmentlengdl (t) 

~ = compatment height (t) 

1000.00 tl 

\A:IIume of Gas or \4por br Oetag1'31ion = Vx LFL 

If!. iii 

The abo\le calcolalions are based on principles developed in the SFPE Haldbook of Fire 

Protection Blgineerilg, 3"' 6ition,2002. 

l:alculalions n based on certain assumptions and ha\le ilherent !irritations. The results 

of such catulalions mayormaynot ha\le reason<ble predicti'W capabilities i:lr a gi\len 

stualion, and should only be imrpmed byan infonned user. 

Mlough each calcumion in the spreadsheet has been 'Wri1ied with the results of hand calculation, 

there is ro absolute g.~arantee oflhe acwracyoflhese c-'culalions. 

Alyqueslions, corrmerts, concerns, and sugge:slions,orto .-Epon an error(s)inthe sp-eadsheet, 

please send an email to mO@lro.govoc rm:s3@lroQOV. 
16-19

Example Problem 16-3

Problem Statement

Assume a leak of 100 ft /min of a 15-percent hydrogen gas/air mixture in a compartment that is 3

29 f c c ct wide x 15 ft long x 12 ft high (w x l x h ). How long would it take to reach a hydrogen

concentration of 2 percent throughout the enclosure, assuming infiltration through multiple

compartment cracks?

Solution

Purpose:

(1) Estimate the time until the room reaches 2% hydrogen concentration.

Assumptions:

(1) Infiltration through compartment leaks.

(2) The mass rate of the fuel is neglected in the conversion of mass.

(3) The specific heat is constant with temperature.

(4) The hydrostatic pressure difference over the height oft he compartment is negligible

compared to the dynamic pressure.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 16_Battery_Room_Flammable _Gas_Conc.xls

 (click on Flammable_Gas_Buildup_Time)

FDT Input Parameters: s

c

-Compartment Width (w ) = 29 ft

c

-Compartment Length (l ) = 15 ft

c

-Compartment Height (h ) = 12 ft

-Enter 100 ft /min as the Leakage Rate 2

-Enter 15% as Percent of Combustible Gas/Air Mixture

-Enter 2% as Combustible Gas Concentration (C)

-Click on Infiltration Through Cracks and select 0.3 from the drop-down menu

Results*

Time 20.9 minutes

*see spreadsheet on next page
16-20

Spreadsheet Calculations

FDT : 16_Battery_Room_Flammable_Gas_Conc.xls (Flammable_Gas_Buildup_Time) s

CHAPTER 16. CALCULATING THE RATE OF HYDROGEN GAS GENERATION 

IN BATTERY ROOMS 

Version1805.0 

The following calculations es timal»l the combustible gas concentration buildup time in enclosed compartments. 

Para mel a-s in YELLOW CELLS a-e Entere::l by the User. 

Parameters in GREEN CELLS are Automatically Selected from the 0 ROP DOWN MENU fort he Infiltration Selected. 

All subsequent outputvalues are calculated by the spreadsheet and based on values specified in the input 

parametl>!rs. This spreadsheet is pro~cted and secure to avoid errors due to a wrong entrv in a cel(s). 

The chapter in the NUR EG should be read before an analysis is made. 

INPUT PARAMETERS 

COMPARTMENT INFORMATION HYDROGEN LEAK INFORMATION 

Compartment Width (IA0 2900 • 

Compartment Length (l:) 1500 • 

Compartment Height(h.:) 1200 

Leakage Rate 10000 

• 

1t.fll ll 

Percent of Combustible Gas/Air MOdure 

Combustible Gas Concentration (C) 

MOdng Efficiency Factor (K) 

1500 p 

200ip 

~IO? It 

~IO? It 

0.3 

Calcwllate 

Mixing Effidency (K Values) for Various Ventil<.,ion Arrangements R~'li I? 10? :Nl"?A 0~. :tfidi? <.\~ ys to . ~~ i Ed . 

1!?-;,...----1 ~~:;,; Ventilation ~~e<net>t 

IJ_Open Door, or Windows J K Sdect Ventilation Arrnngetnent 

Single Exhaust Opening 0.2 

Mu ltiol e Exhaust 0 oe ninas 0.4 Scroll to d~ r~d arrangem entuun Click on ~c1 n 

QJ> nl! <J,R ll ste:;~.J. . K 

Sing li'Exha us t 0 pen ing 0.3 

Sdect Ventilation Arrnngetnent 

Multiole Exhaust Ooeninos 0.5 Scroll to d~ r~d arrangem ~nt Ul~n Click on ~c1 u 

Qniff S I K Sdect Ventilation Arrnngetnent 

Single Exhaust 0 pen ing 0.5 

Multiole Exhaust Ooeninos 0.7 Scroll to d~ r~d arrangem entuun Click on ~c1 u 

Perforated CeilinA K Sdect Ventilation Arrnn 

Single Exhaust 0 pen ing 0.8 

getnent 

Multiole Exhaust Ooeninos 0.9 Scroll to d~ r~d arungem ~ntul ~n Click on ~c1 u 

User Specified Value I K Sdect Ventilation Arrnn 

Single Exhaust 0 pen ing En~rValue I B'olt-1 .ol\lt i ·I 

getnent 

Multiole Exhaust Ooeninos En~rValue 

Scroll to d~ r~d arrangem ~ntuun Click on ~c1 u 

0.15 

002 
16-21

lvi:THOD OF IIFPA 69, STAIIDARD 0 11 EXPLOSIOII PREVEIITIOII SYSTEMS ~'tr~.-., i=PA~. sr.:rd:'don )<,'lJ:>:briP >~r~";'':,_ '19t7 :dtb/"0 'II XI> . 

EstimatirQ Nunber d Theoretical Air Olan:~es 

In p ·(CQ /G)]=· KN 

mere C = combustible gas concen11'31ion 

Q =volume otar in enclosure (i'.tnin) 

G = corrbustible Qas leakaQe me (t:ehrin) 

K = milOng efl\ciencyfactcr (conmnt) 

N = nurrber oflheo..ncal air changes 

Q =volume of ar in enclosure 

Q = 85.00 t :ehrin 

G = corrbustible gas leakage me 

G = 15 (t'hrin) 

N = nurrber oflheoretical air changes 

In p ·(CQ /G)]=· KN 

or 

N = · pn(l • (CO/G)))/ K 

N= OAO 

EstimatirQ Ccmbuditie Gas Ccncentraticn BUidJp lime 

t =(\//leakage me)" N 

mere t = buildl,p time (min) 

V= COI'Tllartment vdume (ft:t) 

leakage me (t:thrin) 

Volumed Compartment 

V=w,. xl ~ X he 

Where 

V= 

N = nurrber oflheoretical air changes 

V = corrpartment vdume (ft:t) 

w .. = comparment Wdlh (ft) 

k = corrpanment Length (t) 

~ = corrpartment HeQht (ft) 

5220.00 t' 

Ccmbuditie Gas Ccncentraticn BUidJp lime 

t = (\/ /leaka!le me) " N 

[!i i,iir~~~~~~20~S~3m~;~nu~e~~II.E:::I !fJI.Iil 

The abo\le calculations are based on method presemd in lhe NFPA69, "Standard on 

&:plosion PreW"rtion S~ms, 1997 6:1iticn. 

Calculations are based on certain assurrpticns and haw inherent !irritations. The results of 

such calcdations may or maynot ha\le reasonable predicti\le capabilities for a given situation, 

and should only be interpreted by3l ini:lnned user. 

Pltho~.gh each calculation in the sp-eadsheet has been \leriied with lhe results of hand calcolatim, 

there is no absoh.te guarantee oflhe accU'3cyof these calcutnions. 

Pnyquestims, comments, concerns, and suggestions, or ro repon an error(s)in 1he spreadsheet, 

please send an emal to mO@JlroQovormxs3@:Jlro.gov. 

17-1

CHAPTER 17. CALCULATING THE FIRE RESISTANCE

OF STRUCTURAL STEEL MEMBERS

17.1 Objectives

This chapter has the following objectives:

• Describe the testing procedures for fire resistance protection of structural steel members.

• Describe the failure criteria for structural steel members.

• Explain how to calculate the fire resistance (failure time) of protected and unprotected

structural steel members.

17.2 Introduction

The fire resistance of structures is important in protecting life and property against the hazards of

fires. Building codes regulate the fire resistance of structures in a number of ways, including

requirements for fire resistance classifications based on such factors as building size, location, and

occupancy. In the United States, fire resistance classifications (fire ratings) of floors, roofs, beams,

partitions, walls, and columns are based on the results of the “Standard Test Method for Fire Tests

of Building Construction and Materials” as defined in ASTM E119. This standard specifies that test

specimens must be “truly representative of the design, material, and workmanship for which

classification is desired.” Testing laboratories throughout North America use gas burners to heat

the furnace in such a manner that the temperature inside the furnace follows the time-temperature

curve illustrated in Figure 17-1. Table 17-1 identifies the points on this curve that determine its

characteristics.

Figure 17-1 Standard Time-Temperature Curve (ASTM E-119)
17-2

Table 17-1. Standard Time-Temperature Curve Points

Time Temperature °C (°F)

5 min 38 (100)

10 min 704 (1,300)

30 min 843 (1,550)

1 hr 927 (1,700)

2 hr 1,010 (1,850)

3 hr 1,052 (1,925)

4 hr 1,093 (2,000)

8 hr 1,260 (2,300)

The floors, roofs, beams, partitions, walls, and columns being tested must remain structurally intact

and limit heat transmission to the unexposed surfaces. Moreover, for fire barriers such as walls the

average temperature increase on the unexposed surfaces cannot exceed 121 °C (250 °F) and

cotton waste on the unexposed surface cannot be ignited. Furnace temperature readings are taken

as an average of at least eight thermocouples at intervals not exceeding 1 minute during the test

period.

A hose stream test is also required for walls and partitions with a rating of at least 1-hour. This test

can be conducted immediately after the fire exposure test or, alternatively, it can be conducted on

a duplicate sample after exposure to fire for half of the rating period, but not more than 1 hour. If

openings develop that permit a projection of water beyond the unexposed surface, the test is

considered a failure.

Load-bearing walls or partitions support a portion of the vertical (gravity) loads from a floor or roof.

During fire test, such assemblies are not restrained on vertical edges and are loaded to the

maximum design load for the test duration. Nonbearing walls or partitions are restrained on all four

edges.

If structural steel members supporting floors or roofs are spaced more than 4 feet apart, the

maximum temperature at any location cannot exceed 704 °C (1,300 °F) and average temperature

cannot exceed 593 °C (1,100 °F) for the following scenarios:

(1) A restrained assembly with up to a 1-hour classification for the full period. For ratings

greater than 1 hour, the temperature limitation applies for half the hourly rating, but not less

than 1 hour.

(2) An unrestrained assembly cannot exceed the temperature criteria shown above for the full

classification or rating period.
17-3

If steel structural members are 4 feet or less on center, the average temperature cannot exceed

593 °C (1,100 °F) for the following scenarios:

(1) A restrained assembly with up to a 1-hour classification for the full period. For ratings

greater than 1 hour, the temperature limitation applies for half the hourly rating, but not less

than 1 hour.

(2) An unrestrained assembly cannot exceed the temperature criteria shown above for the full

classification period.

For steel floor or roof units with spans longer than those tested, the average temperature cannot

exceed 593 °C (1,100 °F) during the classification period. Floors and roofs are loaded to the

maximum design conditions for the classification period.

Columns are loaded to the full design stress and exposed on all four sides to the standard timetemperature curve. The columns must sustain the structural design load for the test period. Where

column protections are not required to carry any of the column load (e.g., the fire-resistive covering

on a steel column), an alternative column test method uses unloaded columns with the following

pass-fail criteria:

(1) The average temperature increase cannot exceed 538 °C (1,000 °F).

(2) The maximum temperature increase of any thermocouple is 649 °C (1,200 °F).

Individual ratings for loaded beams can be established if the beams are tested as part of a floor

assembly; however, the beams must sustain the applied load for the full classification period. The

listing is applicable to beams with a weight-to-heated perimeter (W/D) ratio greater than or equal

to that of the beam tested. This W/D ratio is the factor that allows the interpolation of coating

thicknesses, where W is the weight (lb/ft of length) and D is the heated perimeter (inches) of the

structural member.

17.3 Fire Resistance of Buildings

Buildings consist of various structural elements that have unique fire resistance ratings and belong

to various combustibility groups. The ability of a building to resist collapse during a fire, is called

the fire resistance rating. It is characterized by the fire resistance of structural elements such as

floor, roof, beams, partitions, fire walls or barriers, bearing walls, and columns. Figure 17-2

illustrates typical methods of protecting structural steel elements from fire. Light protection, using

low-density material applied either to the profile of a section or in a box form is the most popular

from an economic point of view. Massive protection, particularly concrete encasement, is used in

special cases. External protections, referred to as complex protection, include such examples as

box protection H-columns with core filling or very thick counter protection. Liquid filling is a special

protection method, in which fire resistance is achieved by filling hollow steel members with water.

This method is a less common but, an effective way of preventing rapid heating of hollow steel

sections. However, a plumbing system is necessary to ensure that the water can flow by

convection from member to member and to avoid excessive pressure when the water is heated.
17-4

Figure 17-2 Typical Methods of Protecting Various Structural Steel Elements from Fire

It is important to distinguish between the actual and required fire resistance ratings of a building.

The actual rating of a building is determined by the minimum actual fire resistance rating and

combustibility group of one of the building’s structural elements. The required fire resistance rating

of a building is standardized and understood to be the minimum rating that the building has to

satisfy given safety requirements. This rating accounts for fire hazards involved in the production

processes within the building, the purpose for which the building is intended, the area, the number

of stories, and the presence of automatic fire detection and extinguishing systems.
17-5

17.4 Fire Resistance of Structural Members

The term fire resistance is used to denote the ability of a building component to resist the thermal

insult of a standard rest fire. This rating is usually given in units of time( e.g., 1 hour, 3 hours, etc.).

The retention load-bearing capacities by structural members during a fire is very important.

Buildings collapse when load-bearing members lose their load-bearing capacity.

The fire resistance of structural members is characterized by their fire resistance ratings, which are

defined as the time elapsed from the start of the fire until the time the structure loses its loadbearing or protective capacity. The failure of structural members begins when they are heated to

critical temperatures. The fire resistance ratings of structural members are determined either

experimentally or by calculations. Experimental methods for determining the fire resistance of

structural members have been standardized (e.g., ASTM E119).

17.4.1 Fire Resistance and Temperature Limits of Steel Elements

Steel is a non-combustible material, however, heat effects the material properties and strength of

structural steel. For structural elements, the only criterion to be considered is the point where the

thermal insult from the fire has weakened the member enough to allow structural collapse of the

element.

The fire resistance (or fire endurance) of steel elements varies greatly. The temperature limits for

structural steel members are based on the criteria contained in ASTM E119. The maximum single

point temperature in a steel beam, column, or girder is 649 °C (1,300 °F) and the allowable average

temperature in these members is 530 °C (1,000 °F). During the testing, failure is assumed to occur

if either the maximum single point temperature or average temperature is exceeded.

17.4.2 Fire Resistance and Temperature Limits of Reinforced Concrete Elements

The fire resistance or fire endurance of reinforced concrete floors, roofs, and walls is often

governed by the criteria for the temperature increase of the unexposed surface, rather than by

structural considerations. The ASTM E119 criteria for the temperature rise of the unexposed

surface, referred to as heat transmission requirements, limit the increase to an average of 121 °C

(250 °F) or a maximum at any one point of 163 °C (325 °F). The purpose of these criteria is to

guard against ignition of combustibles on the non-fire side that may be in contact with the fire

barrier.

A classical method for estimating the maximum surface temperature reached by reinforced concrete

elements is based on of the permanent color changes observed in concrete containing aggregates

of siliceous or limestone rock after exposure to high temperatures. Such color changes depend

upon the maximum temperature. The surface takes on a pink or red hue when exposed to

temperatures of 300–600 °C (572–1,112 °F); dark grey, when exposed temperatures of 600–900 °C

(1,112–1,652 °F); brown, when the maximum temperature reached 900–1,200 °C (1,652–2,192 °F);

or yellow if the temperature exceeds 1,200 °C (2,192 °F) (Neville, 1975).
17-6

Table 17-2 summarizes the ASTM E119 temperature endpoint criteria for structural members. The

endpoint temperatures are selected according to conservative estimates of the maximum allowable

reduction in load-bearing capacity of the structural member, based on an average reduction in

strength attributable to elevated temperatures.

Table 17-2. Temperature Endpoint Criteria for Structural Members (ASTM E119)

Structural Member Location Maximum

Temperature

°C (°F)

Walls/Partitions (bearing and non-bearings) Unexposed side 139 (250)

Steel Columns Average 530 (1,000)

Single point 649 (1,200)

Floor/Roof Assemblies and Loaded Beams Unexposed side 139 (250)

Steel beam (average) 593 (1,100)

Steel beam (single point) 704 (1,300)

Pre-stressing steel 426 (800)

Reinforced steel 593 (1,100)

Open-web steel joist 593 (1,100)

Steel Beams/Girders (not loaded) Average 530 (1,000)

Single point 649 (1,200)

17.5 Failure Criteria for Structural Members

Structural members that are exposed to fire will ultimately fail if the fire is of sufficient duration and

intensity. Failure can occur when the member collapses because it can no longer support the

design load, or when the deflection is so severe that the member can no longer function in the

capacity for it was intended. The failure results from major changes in the mechanical properties

of steel, concrete, and other structural materials as they heat up. The ability of a building to remain

stable during a fire is equated to the temperature increase in the exposed structural elements. This

is based on the fact that the mechanical properties of the structural elements deteriorate as the

temperature of the structural materials increases to some critical level. The changes in material

properties that are most significant to the performance of structural steel members include the yield

strength, modulus of elasticity, and coefficient of thermal expansion. The critical level is generally

defined as the temperature at which the yield strength of the material is reduced to the design

strength and, therefore, the factor of safety approaches unity.
17-7

17.6 Fire Walls and Fire Barrier Walls

NFPA 221, “Standard for Fire Walls and Fire Barrier Walls,” contains design and construction

requirements for fire walls and fire barriers. The basic difference between the two is that fire walls

must remain stable and uncompromised throughout an uncontrolled fire (with sprinklers lacking or

assumed to be ineffective), while a fire barrier is intended to help prevent the passage of fire in

conjunction with other protective measures (such as sprinkler protection).

Fire walls and fire barriers are rated for the number of hours of fire exposure that they can

withstand. Table 17-3 summarizes some rules of thumb to estimate the fire resistance ratings for

walls based on some common construction materials.

Table 17-3. Typical Fire Resistance of Walls

Material Thickness (inches) and Construction Details Fire Resistance (Hours)

Brick 12, all materials 10

8, sand and lime 7

8, clay and shale 5

8, concrete 6

4, clay and shale 11⁄4

4, concrete, sand, and lime 11⁄2 

Hollow partition tile 12, two 6-in. tiles 4

12, unknown number of cells 3

8, all tile arrangements 2

Concrete block 16 nominal, 15e actual 4

12 nominal. 11e actual 3

8 nominal, 7e actual 13⁄4

A fire wall is defined as a wall that separates buildings or subdivides buildings and is intended to

prevent the spread of fire, by providing fire resistance and structural stability. A fire barrier is a wall

that extends to the roof or floor deck above and is intended to restrict the spread of fire by providing

fire resistance.
17-8

In addition to proper structural design, other design considerations are required to maintain the

integrity of the subdividing fire wall or fire barriers, as follows:

• routing of pipes, conduits, and cables to floor level to help prevent the fire wall from being

damaged by collapse on either side

• fire-resistant penetration seals at pipes, conduits, cable trays, and HVAC penetrations

• fire doors for personnel or vehicle openings

• fire resistant exterior wing walls at the ends of the fire walls to prevent fire from spreading

around its ends

• provision of a parapet, which consists of the fire wall penetrating the roof deck and

extending above it

Some fire walls are designed to remain stable after the collapse of a building structure on either

side in the event of an uncontrolled fire.

Fire walls must be designed for a minimum uniform lateral load of 5 pounds per square foot (psf)

from either direction (applied perpendicular to the face of the wall). Where seismic loading governs,

the design load may be considerably higher.

17.7 Fire Resistance Coatings for Structural Steel

Unprotected structural steel loses its strength at high temperatures and, therefore, must be

protected from exposure to the heat generated by building fires. This protection, often referred to

by the misnomer “fireproofing,” insulates the steel from heat. As previously noted, the most

common methods of insulating steel are encasement of the member, application of a surface

treatment, or installation of a suspended ceiling as part of a floor-ceiling assembly capable of

providing fire resistance. Additional methods include sheet steel membrane shields around

members and box columns filled with liquid.

Encasement of structural steel members has been a common and satisfactory method of insulating

steel to increase its fire resistance. In floor systems composed of reinforced concrete slabs

supported by structural steel beams, the encasement can be placed within the floor. Figure 17-3

illustrates this old encasement technique. The major disadvantages of this procedure are the

increased weight and cost, which are attributable to increased framework, concrete, and structural

support. To reduce the weight and cost of encasement, surface treatment utilizing lath and plaster

or gypsum board, or any of a variety of spray-on coatings have been developed, as shown

in Figure 17-4. Sprayed-on mineral fiber coatings are widely used to protect structural steel.

If applied correctly, such coatings provide excellent protection; however, the coating can easily be

knocked off the member during construction or plant modification. Consequently, sprayed-on

mineral coatings are suspect with regard to their effectiveness over long-term use.
17-9

Figure 17-3 Encasement of a Steel Beam by Monolithic Casting

of Concrete Around the Beam

Figure 17-4 Spray-On Mineral Fiber and Noncombustible Protective Coatings
ASTM E119 and NFPA 251 utilize virtually identical testing methods. 1

17-10

Cementitious materials also have been used as sprayed-on coatings, despite the fact that they can

spall during a fire and have experienced adhesion problems in actual use. Thus, effective

application, complete coverage, and long-term maintenance are attributes that must be evaluated

in considering the use of sprayed-on coatings.

The latest advancements have been made with intumescent paints and coatings. These coatings

swell to many times their installed thickness when heated to form an insulation barrier which

increases the fire endurance of the structural steel. They are primarily used for non-exposed steel

subject to elevated temperatures, because prolonged exposure to flame can destroy the char coating.

17.8 Calculating Fire Resistance or Endurance

The traditional approach to structural fire protection is to specify the fire resistance or fire endurance

ratings for construction classifications identified in the building codes. The individual fire resistance

or endurance ratings are established by subjecting various structural members and assemblies to

the standard fire test (ASTM E119 or NFPA 251, “Standard Methods of Tests of Fire Endurance

of Building Construction and Materials”).1

During the past three decades, a substantial amount of research has conducted to develop and

validate computer models of the mechanical and thermal properties of structural members, as well

as compartment fire behavior, heat transfer, and structural performance at elevated temperatures.

These studies have resulted in more realistic predictions of structural behavior in fires than was

possible with the traditional code and standard fire test procedures of the past.

As a result, several empirically derived correlations are available to calculate the fire resistance of

steel columns, beams, and trusses. The correlations are based on curve-fitting techniques using

data gathered by performing the standard test numerous times on variations of a standard

assembly. In some cases, a best-fit line has been drawn for the data point; in other cases, lines

have been drawn conservatively to estimate the fire resistance by connecting the two lowest points.

Numerical methods are also available to estimate the temperature increase in steel structural

elements. The equations in these methods are derived from simplified heat transfer approaches.

Compared to the traditional test approaches, modern calculation methods offer the advantages of

economy and better predictability. These calculation methods calculate either (1) the fire resistance

or endurance that would have been obtained in the standard fire test or (2) structural or thermal

performance in an actual building fire compartment.

17.8.1 Equivalent Fire Resistance of Structural Steel

Fire testing of the structural steel has been ongoing for many years and has yielded substantial

data and experience. The procedures described in the following subsections reflect the methods

for calculating equivalent fire resistance. It should be noted that many of these calculation methods

are obtained from test data. Consequently, one should be cautious when applying these methods

to materials that have not been used in the tests that form the basis for the calculation methods.

For example, the data for structural steel are based on testing of A7 and A36 structural steel, which

have different mechanical properties at both normal and elevated temperatures than the highstrength steels that have become popular in recent years. Consequently, when we use the term

structural steel for fire resistance calculations in this section, we mean A7 and A36 steels.
17-11

17.8.2 Steel Column (Unprotected)

In general, unprotected steel columns of small cross-sectional area have a fire resistance of not

more than 10–20 minutes (ASCE, 1992). However, heavier columns are capable of much better

fire performance. Figure 17-2 illustrates typical sections of unprotected structural steel columns.

Based on theoretical and experimental studies, the following formulae have been developed for

calculating the fire resistance of unprotected steel columns (Milke, 1995):

 (17-1)

and

 (17-2)

Where:

R = fire resistance time (minutes)

W = weight of steel column per linear foot (lb/ft)

D = heated perimeter (in) as shown in Figure 17-5

Figure 17-5 Sections of Unprotected Steel Columns

The fire resistance or endurance of structural steel columns can be improved by insulating the

members. The next few subsections discuss the fire resistance of steel members protected by

various insulation materials.
17-12

17.8.3 Steel Column (Protected with Gypsum Wallboard)

A common protective method is to box in steel columns using gypsum wallboard. Based on the

accumulated fire-test results, the following empirical equation has been developed to determine

resistance or endurance of steel columns protected by gypsum wallboard (Milke, 1995):

 (17-3)

Where:

R = fire resistance time (minutes)

h = thickness of protection (in)

W’ = weight of steel column and gypsum wallboard protection per foot of length (lb/ft)

D = heated perimeter (in) as shown in Figure 17-6

The following formula can be used to derive the total weight of both the column and its gypsum

wallboard protection (W’):

 (17-4)

Where:

W’ = weight of steel column and gypsum wallboard protection per foot of length (lb/ft)

W = weight of steel column per linear foot (lb/ft)

h = thickness of protection (in).

D = heated perimeter (in) as shown in Figure 17-6

Figure 17-6 Heat Perimeters for Common Column and Beam Shapes
17-13

To improve the structural integrity during exposure to fire, gypsum wallboard can be reinforced with

inorganic fiber. Such reinforced gypsum wall board is usually classified by the accredited testing

laboratories, such as Underwriters Laboratories (UL) in North America.

17.8.4 Steel Column (with Low-Density Protection)

Based on experimental and theoretical studies, the following expression has been derived for the

fire resistance of steel sections protected by light (low-density) insulating materials (Milke, 1995):

 (17-5)

Where:

R = fire resistance (minutes)

C1 2 , C = material constants that are known for a specific protecting material

W = weight of steel column per linear foot (lb/ft)

D = heated perimeter (in) as shown in Figure 17-6

h = thickness of protection (in)

As noted above, 1 2 the material constants C and C are specific to a given protection material. For

1 2 cases in which the values of C and C are not known, conservative assessment of the fire

resistance of protected steel columns can be conservatively assessed using the following equations

(ASCE, 1992):

For protection material with a density ( ) of 20 < # 50 lb/ft3

 (17-6)

Equation 17-6 applies to protections consisting of chemically stable materials, such as vermiculite,

perlite, and sprayed material fiber with various binders, and dense mineral wool.

 (17-7)

Equation 17-7 applies to protections consisting of cement pastes or gypsum, such as cementitious

mixtures and plasters.

Where:

R = fire resistance (minutes)

W = weight of steel section per linear foot (lb/ft)

D = heated perimeter (in) shown in Figure 17-6

 = density of protected material (lb/ft )

3

h = thickness of protection (in)
17-14

For protection material with a density ( ) of 10 # # 20 lb/ft3

 (17-8)

Equation 17-8 applies to small round and square columns (less than 6 in.) and thick protection

(h $ 1.5 in.).

 (17-9)

Equation 17-9 applies to any shape, sizes, and thickness of protection.

Where:

R = fire resistance (minutes)

W = weight of steel section per linear foot (lb/ft)

D = heated perimeter (in) as shown in Figure 17-6

 = density of protected material (lb/ft )

3

h = thickness of protection (in)

17.8.5 Steel Column (Protected with Spray-On Materials)

The American Iron and Steel Institute (AISI, 1980) has developed the following formula for two

types of spray-on low-density fire protection known as cementitious and mineral fiber insulation:

Cementitious insulation

 (17-10)

Mineral fiber insulation

 (17-11)

Where:

R = fire resistance (minutes)

W = weight of steel column per linear foot (lb/ft)

D = heated perimeter (in) as shown in Figure 17-6

h = thickness of protection (in)
17-15

17.8.6 Steel Column (Protected by Concrete)

Concrete encasement is another means of protecting for steel columns. The following empirical

formulae have been developed to predict the fire resistance of concrete encased steel columns:

Normal weight concrete protection of uniform thickness on all sides and square shape

 (17-12)

Lightweight concrete protection

 (17-13)

Where:

R = fire resistance time at equilibrium moisture condition, here assumed to be 4-percent of

 the concrete by volume (minutes)

W = weight of steel column per linear foot (lb/ft)

D = developed heated perimeter of steel columns (in) shown in Figure 17-7

h = thickness of concrete protection (in)

H = thermal capacity of steel section at ambient temperature (0.11W Btu/ft-°F)

c

 = density of concrete at ambient temperature (lb/ft )

3

L = interior dimension of one side of square concrete box protection (in) (see note if the box

protection is not square).

Figure 17-7 Concrete-Protected Structural Steel Columns
17-16

Notes:

(1) If the concrete box protection is not square, or if the concrete cover thickness is not

1 2 1 2 constant, h and L are taken as average values [i.e., h = 1⁄2 (h + h ) and L = 1⁄2 (L + L ).]

(2) If the steel column is completely encased in concrete, with all re-entrant spaces filled,

the thermal capacity of the concrete within the re-entrant space may be added to the

thermal capacity of the steel column, thereby increasing the value of H as follows:

 (17-14)

Where:

H = thermal capacity of steel section at ambient temperature (0.11W Btu/ft-°F)

W = weight of steel column per linear foot (lb/ft)

c

 = density of concrete at ambient temperature (lb/ft )

3

L1 = steel column flange width (in)

L2 = depth of steel column (in)

As = cross-sectional areas of steel column (in )

2

17.8.7 Steel Beams

When a beam is fire tested alone or as a part of a floor or roof assembly, it expands as it is heated.

Floor test furnaces encase the specimen in a rigid restraining frame. If the beam is built tightly into

the frame, the frame resists its expansion and moments are generated in the beam. The critical

temperature of beams is much better understood and has limits of 593 °C (1,100 °F) when the

beam is tested as part of an assembly, and 538 °C (1,000 °F) when the beam is tested alone.

W/D concepts can also be applied to assess protection requirements for steel beams in both

restrained and unrestrained assemblies. To determine the fire resistance of steel beams protected

by low-density protection, we can use the same formulae as for steel columns (Equations 17-5

through 17-11), as shown in Figure 17-6.

In the case of beams, only three sides of the beam are exposed to fire Figure 17-6b. The top of the

beam is assumed to be a floor or roof slab, made of a perfectly insulating material. Thus, there is

no heat exchange between the floor or roof slab and the steel. Because only three sides of the

beam are exposed to heat, the values of the heated perimeter (D) of beams in these formulas are

smaller than those of the corresponding column. As a result, the fire resistance of a beam, (i.e.,

the time to reach a specific failure temperature in the steel) is longer than that for a column. In

addition, because the floor or roof on the top of the beam normally absorbs heat transmitted

through the beam, which is not taken into account in the formulae the fire resistance calculated

using these formulae, are more conservative for beams than for columns.
17-17

17.8.7.1 Beam Substitution Correlation for Structural Steel Beams

Protected by Spray-On Materials

For beams protected by spray-on protections, the International Committee for the Study and

Development of Tubular Structures (ICSDTS) (1976) has developed a scaling formula that enables

substitution of one beam for another by varying the thickness of the protection.

Provided the deck is the same and D is calculated only for three-sided exposure, the following

beam substitution equation has achieved code acceptance (Milke, 1995, and UL, 1995):

 (17-15)

Where:

h = thickness of spray-applied protection (in)

W = weight of the structural beam per linear foot (lb/ft); see note

D = heated perimeter of the beam (in) as shown in Figure 17-6; see note

No 1 1 1te: h , W , and D refer to the substitute (unrated) beam and required thickness of fire

protection material.

h2 2 2, W , and D refer to the beam and fire protection thickness in the approved assembly

(rated beam).

Use of above the equation is subject to the following limitations:

• The unrestrained beam in the tested design has a rating of not less than 1-hour.

• The equation is limited to beams with a weight-to-heated-perimeter ratio (W/D) of 0.37 or

greater.

1

• The thickness of the spray-on protection (h ) cannot be less than 0.95 cm (d inch).

The above equation pertains only to the determination of the protection thickness for a beam in a

floor or roof assembly.
17-18

17.8.7.2 Column Substitution Correlation for Structural Steel Columns

Protected by Spray-On Materials

A scaling substitution correlation has also been developed to calculate the required thickness of

spray-on protection for columns (UL, 1995) as follows:

 (17-16)

Where:

h1 = thickness of spray-on protection on the approved assembly (rated column), (in)

h2 = required thickness of spray-on protection on substitute column (in) (smaller wide flange

section)

W1 = weight of the structural column per linear foot for the approved assembly (rated

column (lb/ft)

W2 = weight of the structural column per linear foot for the smaller wide flange section (lb/ft)

D1 = heated perimeter of the column (in), for the approved assembly (rated column) as

shown in Figure 17-6

D2 = heated perimeter of the column (in) for the smaller wide flange section as shown in

Figure 17-6

Use of the above column substitution correlation is subject to following limitations:

• The unrestrained beam in the tested design has a rating of not less than 1-hour.

• The equation is limited to beams with a weight-to-heated-perimeter ratio (W/D) of 0.95 cm

(d inch) or greater.

1

• The thickness of the spray-on protection (h ) cannot be less than 0.95 cm (d inch).

17.8.8 Numerical Method to Estimate the Temperature Increase in Structural Steel Elements

For structural steel elements, there is a critical temperature at which the steel loses so much

strength that it can no longer support its design load. In such cases, calculations of the fire

resistance of the steel members can be reduced to calculating the temperature of the steel. North

American standards assume that the critical temperature condition is reached when the average

temperature in a steel section reaches 538 °C (1,000 °F).

The simple numerical method is based on the principle that the heat entering the steel over the

exposed surface area in a small time step, t (sec), is equal to the heat required to raise the

s

temperature of the steel by T (°C or °F), assuming that the steel section is a lumped mass at

uniform temperature. This numerical method can be further simplified by considering the steel to

be a heat sink, with negligible resistance to heat flow; thus, any heat supplied to the steel section

is considered to be instantly distributed to give a uniform steel temperature.
17-19

17.8.8.1 Unprotected Structural Steel Sections

The following equation calculates the temperature development of an unprotected steel member,

using a quasi-stationary approach, iterated for successive time steps of t (sec):

 (17-17)

Where: Ts = temperature in the steel member (°F)

F/V = ratio of weight of steel section per linear foot and heated perimeter (m )

-1

s

 = density of steel (kg/m )

3

s

c = specific heat of steel (J/kg-K)

hc = convective heat transfer coefficient (W/m -/K) 2

 = Stefan Boltzmann constant (kW/m -K )

2 4

 = flame emissivity

s

c = specific heat of steel (Btu/lb-°F)

Tf = fire temperature (°F)

Ts = steel temperature (°F)

t = time step (sec)

Emissivities for various types of construction are given in Table 17-4 (Buchanan 2001).

Table 17-4. Resultant Emissivity for Different Types of Construction

Type of Construction Resultant Emissivity

Column exposed to fire on all sides 0.7

Column outside facade 0.3

Floor girder with floor slab of concrete (only the underside of the bottom

flange being directly exposed to fire)

0.5

Floor girder with floor slab on the top flange girder of I section for which

the width-depth ratio is not less than 0.5

0.5

Girder of I section for which the width-depth ratio is less than 0.5 0.7

Box girder and lattice girder 0.7
17-20

The f fire temperature (T ) is evaluated at the midpoint of each time step. If the exposure under

f

consideration is that associated with the ASTM E119 test, T at any time (t) is obtained from the

following expression:

 (17-18)

Where:

C1 f = 620 with a fire temperature T

Ta = ambient temperature (°F) (Milke, 1995)

The maximum time step ( t) can be determined from the following relationship (Molhotra, 1982):

 (English units) (17-19)

Table 17-5 shows a spreadsheet for calculating steel temperature using this method (Buchanan, 2001).

Kay et al., (1996) have shown that this type of calculation can give a good prediction of steel

temperatures in standard fire resistance tests.

Table 17-5. Spreadsheet Calculation for the Temperature of Steel Sections

(Buchanan, 2001)

Time Steel

Temperature

s

(T )

Fire Temperature

f

(T )

Difference in

Temperature

Change in Steel

Temperature

s

(∆T )

1

t = t Initial steel

s0 temperature (T )

Fire temperature

halfway through

time step (at t/2)

Tf s0 - T Calculate from Equation

f

(17-17) with values of T

and Ts0 from this row

2 1 t = t + ∆t Ts

 from previous

s

time step + T

from previous

row

Fire temperature

halfway through

time step

1 (at t + t/2)

Tf s - T Calculate from Equation

f

(17-17) with values of T

and Ts from this row
17-21

17.8.8.2 Protected Structural Steel Sections

Protected steel members heat up more slowly than unprotected members because of the applied

thermal insulation, which protects the steel from rapid absorption of heat. The calculation method

for protected steel members is similar to that for unprotected steel members. However, the

equation is slightly different and does not require a heat transfer coefficient because it is assumed

that the external surface of the insulation is at the same temperature as the fire gases, while the

internal surface of the insulation is at the same temperature as the steel.

The thermal capacity of the insulation material may be neglected if the following inequality is true:

 (17-20)

Where:

W/D = ratio of weight of steel section per linear foot and heated perimeter (lb/ft )

2

i

c = specific heat of insulation (Btu/lb-°F)

i

 = density of insulation (lb/ft )

3

h = thickness of insulation (in)

If the thermal capacity of the insulation layer is neglected, the temperature rise in the structural steel

element can be calculated using the following equation:

 (17-21)

Where:

Ts = temperature increase in steel (°F)

i

k = thermal conductivity of insulation material (Btu/ft-hr-°F)

i

 = density of insulation (lb/ft )

3

i

c = specific heat of insulation material (Btu/lb-°F)

s

c = specific heat of steel (Btu/lb-°F)

h = thickness of insulation (in)

W/D = ratio of weight of steel section per linear foot and heated perimeter (lb/ft )

2

Tf = fire temperature (°F)

Ts = steel temperature (°F)

t = time step (sec)
17-22

If the thermal capacity of the insulating material must be accounted for, as in the case of gypsum

and concrete insulating materials, Equation 17-21 can be modified as follows:

 (17-22)

The f fire temperature (T ) is evaluated at the midpoint of each time step. If the exposure under

f

consideration is that associated with the ASTM E119 test, T at any time (t) is obtained from the

following expression:

 (17-23)

Where:

C1 f = 620 with a fire temperature T

Ta = ambient temperature (°F) (Milke, 1995)

The maximum time step ( t) can be determined from the following relationship (Molhotra, 1982):

 (English units) (17-24)

Table 17-6 summarizes the typical thermal properties of various insulation materials.

Table 17-6. Thermal Properties of Insulation Materials (Buchanan, 2001)

Insulation Material Density

i

(lb/ft )

3

Thermal Conductivity

ki

(Btu/ft-hr-°F)

Spec iific Heat c

(Btu/lb-°F)

Sprays

Sprayed mineral fiber

Perlite or vermiculite plaster

High-density perlite or vermiculite plaster 

19

22

35

0.06936

0.06936

0.06936

0.2868

0.2868

0.2868

Boards

Fiber-silicate or fiber-calcium silicate

Gypsum plaster

38

50

0.0867

0.1156

0.2868

0.4063

Compressed fiber board

Mineral wool or fiber silicate 10 0.1156 0.2868

The spreadsheets for calculating steel temperature using this method are based on Table 15-5

(Buchanan, 2001).
17-23

17.9 Assumptions and Limitations

The methods discussed in this chapter are subject to several assumptions and limitations:

(1) The heat transfer analysis is one dimensional.

(2) Correlations are based on the analysis of data resulting from performing the standard test

numerous times, using curve-fitting techniques to establish the various correlations.

(3) As the structural member heats up, its structural properties can change substantially.

(4) Equation-specific limitations apply (see the various equations throughout this chapter).

17.10 Required Input for Spreadsheet Calculations

The user must obtain the following information to using the spreadsheet:

(1) dimensions of the steel member in question

(2) thermal properties of the applied insulation

17.11 Cautions

(1) Use the appropriate spreadsheet:

(17.1_FR_Beams_Columns_Substitution_Correlation.xls,

17.2_FR_Beams_Columns_Quasi_Steady_State_Spray_Insulated.xls,

17.3_FR_Beams_Columns_Quasi_Steady_State_Board_Insulated.xls,

or 17.4_FR_Beams_Columns_Quasi_Steady_State_Uninsulated.xls)

on the CD-ROM for calculating the fire resistance of structural steel members.

(2) Make sure you are on the correct page of the spreadsheet (for columns or beams).

(3) Make sure to enter all input parameters using the correct units.

(4) Equation (23) is only valid up to 1,000 °F (538 °C) where the carbon steel structural

members begin to fail. Predicted temperatures above 1,000 °F (538 °C) are neither

accurate nor valid.

17.12 Summary

The fire resistance/endurance of the beams, girders, and columns that comprise the structural

frame of the walls, partitions, floor/ceiling assemblies, and roof/ceiling assemblies that serve as

barriers to flame movement have been a historical basis for classifying buildings and rating frame

and barrier capabilities.

The selection of building materials and the design details of construction have always played an

important role in building fire safety. Two of the important structural fire considerations are the

ability of the structural frame to avoid collapse and the ability of the barrier to prevent ignition and

resulting flame spread into adjacent spaces.

Heat transfer analyses are applied to determine the time period required to heat structural members

to a specified critical temperature. The required time period is then defined as the fire

resistance/endurance time of the member.

The critical temperature of a structural member can be determined by referring to the temperature

endpoint criteria cited in ASTM E119 or by a structural assessment, as discussed in this chapter.
17-24

17.13 References

AISI, Designing Fire Protection for Steel Columns, 3 Edition, American Iron and Steel Institute, rd

Washington, DC, 1980.

ASCE Manuals and Reports on Engineering Practice, No. 78, “Structural Fire Protection,”

Lie, Editor, American Society of Civil Engineers, New York, 1992.

ASTM E119, “Standard Test Methods for Fire Tests of Building Construction and Materials,” ASTM

Fire Test Standard, 5 Edition, American Society of Testing and Materials, West Conshohocken, th

Pennsylvania, pp. 793–813, 1999.

Buchanan, A.H., Structural Design for Fire Safety, John Wiley & Sons Limited, New York, 2001.

International Committee for the Study and Development of Tubular Structure, (ICSDTS), 1976.

Kay, T.R., R.B. Kirby, and R.P. Preston, “Calculation of Heating Rate of an Unprotected Steel

Member in a Standard Fire-Resistance Test,” Fire Safety Journal, Volume 26, pp. 327–350, 1996.

Milke, J,A., “Analytical Methods for Determining Fire Resistance of Steel Members,” Section 4,

Chapter 9, SFPE Handbook of Fire Protection Engineering, 2 Edition, P.J. DiNenno, Editor-in- nd

Chief, National Fire Protection Association, Quincy, Massachusetts, 1995.

Molhotra, H.L., Design of Fire-Resisting Structures, Chapman and Hall, 1982.

Neville, A.M., Properties of Concrete, Pitman Publishing Limited, 1975.

NFPA 221, “Standard for Fire Walls and Fire Barrier Walls,” 2000 Edition, National Fire Protection

Association, Quincy, Massachusetts.

NFPA 251, “Standard Methods of Tests of Fire Endurance of Building Construction and Materials,”

1999 Edition, National Fire Protection Association, Quincy, Massachusetts.

UL Fire Resistance Directory, Volume 1, Underwriters Laboratories, Inc., Northbrook, Illinois,

p. 19, 1995.
17-25

17.14 Problems

Example Problem 17.14-1

Problem Statement

Calculate the thickness of spray-on fire protection required to provide a 2-hour fire resistance for

a W12 x 16 beam to be substituted for a W8 x 18 beam requiring 1.44 in. of protection for the same

rating.

Solution

Purpose:

(1) Estimate the spray-on thickness required for the beam substitution.

Assumptions:

(1) The 1.44 in. of spray-on provides the W8 x 18 beam 2 hours of fire resistance.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 17.1_FR_Beams_Columns_Substitution_Correlation.xls

 (click on Beam)

FDT Input Parameters: s

-Known beam insulation thickness

-Select W8 x 18 for Rated Beam

-Select W12 x 16 for Substitute Beam

Results*

Substitute Beam

Spray on Thickness

1.6 in

*see spreadsheet on next page
17-26

Spreadsheet Calculations

FDT : 17.1_FR_Beams_Columns_Substitution_Correlation.xls (Beam) s

CHAPTER 17. ESTIMATING THICKNESS OF FIRE PROTECTION SPRAY-APPLIED 

COATING FOR STRUCTURAL STEEL BEAMS (SUBSTITUTION CORRELATION) 

Version 1805.0 

For beams pro~cted by spray. applied protections, follcwing correlation enables substitution of one 

beam from another by varying the thick ness of the fire protection insulation. 

Parameters in YELLOW CELLS ~e Entered by the User. 

ParamSersin GREEN CELLS are Automatically Selededfromthe DROP DOWN MENUforthe Beam Selede::l. 

AJI subsequent output values are calculated by the spreadsheet, and based on values specified in the input 

parameWrs. This spreadsheet is protected and secure to avoid errors due ro a wrong entry in a cel(s). 

The chapter in the NU REG should be read before an analysis is made. 

INPUT PARAMETERS 

Rated Design Thickness of Beam Insulation (Ti) 

Knnoo bs •lstjnn Rat jog 

Weightofthe Beam (\Ali) 

Heated Perimeter of Beam (D il 

I !nknnoo bs •lstjnn Rat jog 

Weightofthe Beam (Vl/1) 

Heated Perimeter of Beam (D ~ 

SECTIONAL FACTORS FOR STEEL BEAMS 

Select the Beam with~ 

rcting for insulction thickness 

I. W8 x18 

SUbSCiilll 2 

(Rated Beam) Calculate 

1811blll 

t========3~1~.5~7 ;n 

16.0011•111 

35.5110 

Select the Beam Wth • 1nknnoo 

rating for insulation thic!G'less 

W12 X 16 H 

Subscrill l 1 

(Substittne Beam) 
17-27

ESTIMATING THICKNESS OF FIRE PROTECTION INSULATION ON UNRATED BEAM l'l:'l!r~•o: : u.,:{,* Ss <tr.c~ D..I?.:.t>. y. \.tttlm;? 1. 9~ P~;? . 

T· = ((Wi 0, +0.6)T,)'(W1/D· + 0.6) 

Where T· =calculated thickness of fire protection insulation on unrated beam (in) 

T:r =design thickness of insulation on rated beam (in) 

W · = ~ight of beam with uri<nown insulation rating (lblft) 

W:r = ~ight of design rated beam (lblfO 

D· =heated perime~r of unrabld beam (in) 

D:r =heated perimetl>!r of the rated beam (in) 

Require:! EquiWent Thic!G'less of Fire Prote:tion Insulation on Unrate::l Beam 

T· = 

The above calculations are based on method developed in the UL Fire Resistance 

Directory. Volume 1, 1995. Calculations are based on certain assumptions and have inherent 

limitations. The results of such calculations may or may not have reasonable 

predictive capabilities for a given sib.Jation, and should only be in~rpre~d by an 

informed user. 

Although each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolute guaran~e of the accuracy of these calculations. 

Any questions. comments, concerns, and suggestions, or to report an error(s) in the spreadsheet 

please send an email to nxi@nrc.gov or rro<:s3@uc.gov. 
17-28

Example Problem 17.14-2

Problem Statement

Use the quasi-steady-state heat transfer approach to determine the fire resistance of a W24 x 76

steel beam protected with 0.5 in. of spray-on mineral fiber material. Sprayed-on mineral fiber has

the following thermal properties:

i

• Thermal Conductivity, k = 0.06936 Btu/ft-hr-°F

i

• Specific Heat, c = 0.2868 Btu/lb-°F

i

• Density, ρ =19.0 lb/ft3

Solution

Purpose:

(1) Estimate the fire resistance of the beam.

Assumptions:

(1) The heat transfer is quasi-steady-state.

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 17.2_FR_Beams_Columns_Quasi_Steady_State_Spray_Insulated.xls

 (click on Beam)

FDT Input Parameters: s

-Select W24 x 76 beam

-Enter 0.5 in spray-on thickness

-Select “Sprayed Mineral Fiber” from Insulation Type drop-down menu

Results*

Fire Resistance 42.5 min

*see spreadsheet on next page
17-29

Spreadsheet Calculations

FDT : 17.2_FR_Beams_Columns_Quasi_Steady_State_Spray_Insulated.xls s

CHAPTER 17. ESTIMATING FIRE RESISTANCE TIME OF STEEL BEAMS 

PROTE CTEO BY FIRE PROTECTION INSULATION (QUO. SI-STEA OY-STATE APPROACH) VH•Ion tses.e 11~ 1:1CY.IfV e:t:U~I m t" tol~· I~ 1ft I t ill b'o2 to~t 1:1 1l\l: .. ~ ~tl l> o\1 f>IO• c • 4 lf/ll>l~ttllt t" lfdtd:n 

U~h.l~~ll:il. 

Flmom~- n EllO'NCEtte.u~ 81-~4 t>y ~ ll ~r. 

Flmom~- n GREEII Elte.utAIItlm oll l.ilel -4 Tllm t" OftOP OOWIII.IBIII J:>r ~ &fo.'m lln4 1h0111l h n e~le -4. 

fl ~t> ~<l\tnl t«ll >:.:t.~ l ~t e:t11~4 If/ I~ u·~ltl~~~.~ t>~~<l t.t~~~~ w~nt-l to •~ ,.,.~,, 

~~~Mh . 1111 !itft~IH~IIIJ>I it it<l Ut lo~C14 RO U lo V.ICfV t ... )' h~ . 

11~ U>b In I~ IIU I';.Bj !l..,l<ll>t ll~1:1t ~H111:ill)'lli II - lt. 

Od'l llO'I'Cf>•~· ..... l>tt- 1.1~11~ (p) 

11.-1»:11 ca .. -..: t.tl/d'Ct~~ .. ,...,fk4 r.b~ll:ii J 

Cltt <l t : Ht~ o1Qtt~.AWI!t 1.1~·11~ ) 

;ro~ttkni .At Tdolltd~rt (rJ 

Cltt <ll : Ht~ o1~tl (c,) 

SECTIOIIAL FACTOR$ R:IR STEEL BEAf.1 $ 

e~I~OI &.,,m 

, ,. - t ·l eoAII 1o 4t <t"" bt llm <t ~ "'"' Cllok on le ¢n 

THERf.1Al PROPERTIES OF $ PRAY-.4PPLIED IIU ULATDII f.1 ATERIAL$ 

............ _ ...ll ...... -· *-~~~-

*'"""'""'"" • c ........... ,.., . ..... ........... "f, .. ....... 'f) 

Q>t~i 4Mht ~11~1 • O,Clll:n .,.. ~llllt « t.ttrhi o.l~ " O,ClllJi.> .,.. :: 7:: .. :l~ mil:~•~ " O,ClllJi.> .,.. lhkt~~ lhkt~~ Ehh l~ 

~""'"'~ ~'""'"""' "' ~·'-" .. "'~"""''1<~..,.,.-1 1L-•~-·-

EHir.tATIIIG FIRE RESIHAIICETir.tE USIIIG TE TE APPROACH 

~-~ ....... ~ .... -......... ~ ..... ~--· ..... ~.,~-.. --· ~ ... --"'-""""" .. ""'-· )-_ ..... ,;JIJUJ.,_ .. JU 

c,V\VO> Zc p,h 

V\h<t c, • ll>t'Ci t : ~~~1 01' ~ti h .. -' f) 

l fi) 

V\\'0• 1~ )01'V.~ij"l o1 ~tl dcn l>tr h~ 1XII~'II I-~ 1>~1tolt b (f>i'll) 

p. old'l !/01'11• ~ ... , ...... ~~~~~~ (1h.'l1') 

( • !I>~I'I I-1 01'H• tt 4M~IIIt~ l11, .. -'f) 

h•l .. ~ 11 01'11>•~1fk<l lf~dcn 1 hi t>~~,., (In 

0 

h m1"no" rt fll n e-tt e..'""' 

tT, • (lo;,o'(c, " 'l.VO+ IIZc,p.h")(r · T.) t l 

t. • hno~~ caontUI/d'H• '"~I>tN ~·II~ ,.l -' ) 

p • <l llt/01'11• .,,,,. .... ~~~~~~ (1h.'l1') 

c • !i>t"Ci I~~I 01'$1>1~1fk4 ~~ll:ii it-' ) 

c., • <l •~~l o1 ~tl (na.,-'f) 

h•l .. t~ ll 01'11>•~1flt f~dcn l hi t>~~,., (IIi 

V\VO• 1~ )01'V.~Whl o1 ~tl dcn lttr ·~~ 1XII~'II I-~ 1ttltolt b (f>i'll) 

T.• .t t )t>OIUt bollttr~rt" \ f) 

011.(.1" 

O IICUI3t& 
17-30
17-31

Steel T errper.Jture 

12000 

E 1oooo 

---- E • 

m •

0 

~ 

~ • ~ 

E 

,'!!. 

8000 

6000 

4000 

2000 

0 

0 

-

----

100 

__....... 

---

200 

Time(min) 

The Failure Tempel'3ture i:lr Steel Beams is .Assumed at 1000 •F (538 "C) 

M!.Jil 

Th .. )OV~ ca• H1tb" ate baad o• plltc j)l:4 '" ~ tt ~d " 1u soc'"t,roTFIIe Plo, c1m 

E• lt ~m fPE) Ha •<lboo•: OTF h P D'C1JH E• lu ~ lllg,J"' 6:110H 2002. 

CatU.'IIm; al~ l>aHd o• 0: ftlll a 64Ullp1D" a •d <f.!~ II·~ IUt 1111 ltiO>U. TH I~H It 

of4 •c• ca • hO>u mar Ollllay •ot <f.!~ •~a so ab ~ p1~d•:U ~ cal:..'lbiii!J?; Dl a gllu 

4ll'la0,_ ,aUI$ •o••:l l{ b~ "' qm'd I){ a • IU PII~d IH I. 

,:.,Uo tg• ~<t · ca l hOH 111U pl~aO~ •Ht •a s I=*U !J~ lrl?d WIG 1U I~H It OT au a• l 1.1\b•, 

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18-1

CHAPTER 18. ESTIMATING VISIBILITY THROUGH SMOKE

18.1 Objectives

This chapter has the following objectives:

• Identify the hazard results of reduced visibility.

• Identify the factors that influence visibility.

• Describe the effects of smoke on nuclear power plants (NPPs).

• Explain how to calculate the visibility through smoke.

18.2 Introduction

As described in Chapter 9, smoke from a fire in a compartment rises in a plume to the ceiling.

As the plume rises, air is entrained into it, thereby increasing the volume of smoke and reducing

its temperature. The smoke spreads out beneath the ceiling and forms a layer that deepens as the

compartment begins to fill with smoke. The production of smoke (smoke particulates) reduces

visibility as a result of light absorption and scattering. Visibility through smoke is defined in terms

of the furthest distance at which an object can be perceived (distance at which an object is no

longer visible). Smoke obscures vision and causes irritation and watering of the eyes. Most

notably, the intensity of smoke production has the greatest impact on reduction of visibility in a fire

compartment or zone. Reduced visibility and inhaled smoke particles are the most frequent

reasons of panic, which disorganizes evacuation and prolongs both rescue and firefighting

operations. Moreover, in the consequence of absorption, smoke particles are ideal carriers of toxic

gases and intensify the process of absorbing poisonous compounds into the human body.

The lachrymatory (causing or tending to cause tears) effects of smoke and hot gases, such as

aldehydes or acids associated with smoke particles, have been shown to be important in interfering

with vision. Visibility is generally much better at floor level than at higher levels in a compartment,

so the possibility of crawling to safety raises the question of the height at which exit signs should

be located. However, if sprinklers operate, their cooling and entrainment effects tend to bring the

smoke closer to the floor. Moreover, fog (which may result from the use of sprinklers) will interfere

with vision. There is currently no universally accepted position.

18.3 Smoke Obscuration

Unlike temperature, heat flux, or toxic gases, obscured visibility is not, itself, lethal. A hazard

results only if the reduced visibility prevents required manual operator action or escape activity.

This hazard is crucial, however, and smoke production has, therefore, been regulated longer than

any other product of combustion. Evaluations have shown that personnel remote from the source

of a fire are particularly at risk from fire effluent in post-flashover fire scenarios (Beitel et al., 1998).
18-2

Toxic gases kill largely because people cannot see to find escape routes and because they become

disoriented and panic as a result of inhaling irritating gases. A little smoke makes people walk

faster, while an increased amount slows the walking speed. Smoke also represents a

psychological barrier to an occupant entering a room, often causing people to seek an alternative

route and possibly causing the occupant to become trapped in a room without a safe exit (door or

window). The same is true for reactor operators who may have to perform specific manual actions

in a smoke-filled environment.

18.4 Effect of Smoke on Nuclear Power Plants

Sensitivity studies have shown that prolonged firefighting response times can lead to a noticeable

increase in fire risk. Smoke, identified as one of the major contributors to prolonged response

times, can also cause misdirected suppression efforts, hamper the ability of main control room

(MCR) operators to safely shut down the plant, initiate automatic suppression systems in areas

away from the fire, and fail electrical equipment.

Any number of possible fire scenarios could be considered threats to safe NPP operations. For

example, a fire in turbine building, cable spreading room (CSR), or the control building can generate

toxic combustion products that directly affect the habitability of the MCR or auxiliary shutdown

areas. One exception would be a fire in the MCR, itself. The MCR is unique in several ways that

significantly reduce the likelihood of a generalized area fire. First, the MCR is continuously manned

and, hence, very rapid fire detection and intervention times are expected. This also implies that the

transient fuel sources should be very effectively controlled and limited. Second, high-energy

electrical equipment is not typically housed in the MCR and, hence, the number of potential highenergy fire sources is limited. Given these factors, the occurrence of a large, generalized fire in the

MCR is not considered likely.

18.5 Estimating Visibility Through Smoke — Jin Method

As previously discussed, smoke particles and irritants can reduce visibility and, while loss of

visibility is not directly life threatening, it can prevent or delay escape and thus expose people to

the risk of being overtaken by fire. Visibility depends on many factors, including the scattering and

absorption coefficient of the smoke, size and color of smoke particles, density of smoke, and the

eye irritant effect of smoke. Visibility also depends on the illumination in the room, whether an exit

sign is light-emitting or light-reflecting, and whether the sign is back- or front-lighted. An individual’s

visual acuity and mental state at the time of a fire emergency are other factors.

Most visibility measurements through smoke have relied on test subjects to determine the distance

at which an object is no longer visible. However, variations in visual observation of up to 25 to

30 percent can occur with the same observer under the same test conditions but at different times.

A correlation between the visibility of test subjects and the optical density of the smoke has been

obtained in extensive studies by Jin (1974, 1975, 1978, and 1985) (also reported by Klote and

Milke, 2002).
18-3

Based on those studies, the relationship between visibility and smoke obscuration is given by the

following expression:

 (18-1)

Where:

S = visibility (ft)

K = proportionality constant

m

 = specific extinction coefficient (ft /lb) 2

mp = mass concentration of particulate (lb/ft )

3

The proportionality constant (K) is dependent on the color of the smoke, illumination of the object,

intensity of background illumination, and visual acuity of the observer (Klote and Milke, 2002).

Table 18-1 provides values of the proportionality constant based on the research of Jin.

Table 18-1. Proportionality Constants for Visibility

Situation Proportionality Constant (K)

Illuminated signs 8

Reflecting signs 3

Building components in reflected light 3

The m specific extinction coefficient ( ), depends on the size distribution and optical properties of

the smoke particulates. Seader and Einhorn (1976) and Seader (1943) obtained values for the

m

specific extinction coefficient ( ) from pyrolysis of wood and plastics, as well as from flaming

m

combustion of these same materials. Table 18-2 provides values of .

Table 18-2. Specific Extinction Coefficient for Visibility

Mode of Combustion Specific Extinction Coefficient − αm (ft /lb) 2

Smoldering combustion 21,000

Flaming combustion 37,000

Jin also found that walking speed decreases as smoke density increases; i.e., visibility decreases.

It can be expected that a decrease in the visibility of walls and floors would cause subjects to slow

down. In thick irritating smoke, tears prevented the subjects from seeing the words on signs and

caused them to walk in an irregular manner or along the wall. For low-density smoke, however, the

walking speeds in irritating smoke were about the same as those in non-irritating smoke.
18-4

The mass p concentration of particulate (m ), is given by the following expression:

 (18-2)

Where:

mp = mass concentration of particulate (lb/ft )

3

Mp = mass of particulates produced (lb)

V = volume of smoke in the space (ft )

3

The smoke particulates produced by a fire primarily consist of soot, and the production of

particulates can be estimated as follows:

 (18-3)

Where:

Mp = mass of particulates produced (lb)

p

y = particulate yield

Mf = mass of fuel burned (lb)

Tab ple 18-3 lists values of particulate yield (y ) for a number of materials from small-scale

experiments of turbulent flaming combustion.

Table 18-3. Smoke Particulate Yield (Klote and Milke, 2002)

Ma pterial Particulate Yield - y

Wood (Red Oak) 0.015

Wood (Douglas Fir) 0.018

Wood (Hemlock) 0.015

Fiberboard 0.008

Wool (100-percent) 0.008

Acrylonitrile-Butadiene-Styrene (ABS) 0.105

Polymethylmethacrylate (PMMA; PlexiglasTM) 0.022

Polypropylene 0.059

Polystyrene 0.164

Silicone 0.065

Polyester 0.09

Nylon 0.075

Silicone Rubber 0.078

Polyurethane Foam (Flexible) 0.188

Polyurethane Foam (Rigid) 0.118
Table 18-3. Smoke Particulate Yield (Klote and Milke, 2002)

Ma pterial Particulate Yield - y

18-5

Polystyrene Foam 0.194

Polyethylene Foam 0.076

Phenolic Foam 0.002

Polyethylene (PE) 0.06

Polyvinylchloride (PVC) 0.172

Ethylenetetrafluoroethylene (ETFE; TefzelTM) 0.042

Perfluoroalkoxy (PFA; TeflonTM) 0.002

Fluorinated polyethylene-polypropylene (FEP; TeflonTM) 0.003

Tetrafluoroethylene (TFE; TeflonTM) 0.003

18.6 Assumptions and Limitations

The method discussed in this chapter is subject to several assumptions and limitations:

(1) This method takes into account the irritating and non-irritating effects of smoke.

(2) The correlations are developed for smoldering and flaming combustion.

18.7 Required Input for Spreadsheet Calculations

The user must obtain the following information before using the spreadsheet:

(1) compartment width (ft)

(2) compartment length (ft)

(3) compartment height (ft)

(4) fuel type (material)

(5) mass of fuel burn (lb)

18.8 Cautions

(1) Use spreadsheet (18_Visibility_Through_Smoke.xls) on the CD-ROM for estimating visibility

through smoke.

(2) Make sure to enter the input parameters in the correct units.
18-6

18.9 Summary

This chapter describes a method of calculating the visibility through a smoke layer based on

experimental correlations and data. The visibility through thin smoke primarily depends on physical

obscuration; however, when the smoke is relatively thick, the physiological irritant becomes the

dominant factor in impairing visibility. The correlation presented was obtained from laboratory-scale

fires; smoke particulate production is expected to vary with the size of the fire and the orientation

of the fuel. Equation 18-1 can be used to calculate visibility in such large fires.

18.10 References

Beitel, J.J., C.L. Beyler, L.A. McKenna, and F.W. Williams, “Overview of Smoke Toxicity Testing

and Regulations,” NRL/MR/6180-98-8128, Naval Research Laboratory, Naval Technology Center

for Safety and Survivability Branch, Chemistry Division, Washington, DC, April 15, 1998.

Jin, T., “Visibility Through Fire Smoke, in Main Reports on Production, Movements and Control in

Buildings,” Japanese Association of Fire Science and Engineering, pp. 100 –153, 1974.

Jin, T., “Visibility Through Fire Smoke,” Report of the Fire Research Institute of Japan, 5 (2),

pp. 12–18, 1975.

Jin, T., “Visibility Through Fire Smoke,” Journal of Fire and Flammability, Volume 9, No.2,

pp. 135–155, April 1978.

Jin, T. “Irritating Effects of Fire Smoke on Visibility,” Fire Science and Technology, Volume 5, No.

1, pp. 79–90, 1985.

Klote, J.H., and J.A. Milke, Principles of Smoke Management, American Society of Heating,

Refrigerating, and Air Conditioning Engineers, Inc. (ASHRAE), and Society of Fire Protection

Engineers (SFPE), ASHRAE Special Publication, 2002.

Seader, J., and I. Einhorn, “Some Physical, Chemical, Toxicological, and Physiological Aspects of

Fire Smokes,” National Science Foundation (NSF) Report, Utah University, 1976.

Steiner, A.J., “Method of Fire Hazard Classification of Building Materials,” ASTM Bulletin, American

Society of Testing and Materials (ASTM), Philadelphia, Pennsylvania, pp. 12–18, March 1943.
18-7

18.11 Problems

Example Problem 18.11-1

Problem Statement

A c c c compartment is 30 ft width x 20 ft long x 15 ft high (w x l x h ). In the center of the compartment,

1 lb of polypropylene is involved in flaming combustion:

(a) From the center of the compartment, can you see the “Reflecting Exit Sign” at either end of the

compartment?

(b) What if you increase the mass of burned fuel (polypropylene) to 2 lbs?

Solution

Purpose:

(1) Determine the visibility of the exit sign.

Assumptions:

(1) Complete burning within the method specified

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 18_Visibility_Through_Smoke.xls

FDT Input Parameters: s

c

-Compartment Width (w ) = 30 ft

c

-Compartment Length (l ) = 20 ft

c

-Compartment Height (h ) = 15 ft

-Mass of fuel burn = 1 lb

-Select Polypropylene

-Select Reflecting Signs

-Select Flaming Combustion

Results*

1 lb of material 2 lb of material

Visible Distance 12.37 ft (3.77 m) 6.18 ft (1.88 m)

*see spreadsheet on next page

Therefore, the signs placed at either end of the room (10 feet away) are visible with 1 lb

of material burning, but would not be visible if 2 lb of material was burned.
18-8

Spreadsheet Calculations

(a) FDT : 18_Visibility_Through_Smoke.xls (1 lb polypropylene) s

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l>k~ ' IN'ol ~"o~al b n ·,J¢ .. CIJO'.' Ctfi\Xl)¢ .. CIJO'.'. 
18-12

Example Problem 18.11-2

Problem Statement

A compar c c ctment is 10 ft wide x 30 ft long x 12 ft high (w x l x h ). What is the minimum amount (lb)

of rigid polyurethane foam involved in smoldering combustion necessary to obstruct the visibility

for the length of the compartment to a building compartment in reflective light?

Solution

Purpose:

(1) Determine the minimum mass of burning fuel that will obscure the sign.

Assumptions:

(1) Complete burning within the method specified

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 18_Visibility_Through_Smoke.xls

FDT Input Parameters: s

c

-Compartment Width (w ) = 10 ft

c

-Compartment Length (l ) = 30 ft

c

-Compartment Height (h ) = 12 ft

-Mass of fuel burn = variable

-Select Polyurethane Foam (Rigid)

-Select Reflecting Signs

-Select Smoldering Combustion

Results*

Visible Distance Mass of fuel burn

30 ft (9.42 m) .14 lb (.064 kg)

*see spreadsheet on next page
18-13

Spreadsheet Calculations

FDT : 18_Visibility_Through_Smoke.xls s

CHAPTER 18. ESTIMATING VISISILITY THROUGH SMOKE 

Version 1805 D 1h~ 1:11)Wh,l .:t U~t ; IM~k I~ Hl\cf:t Cl>fC cn4UII'tHII'U. 

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PARTICULATE YIELD FOR VY'Ell-VENTILATEO FIRES OF SOLID FUELS 

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18-14

ESTIMATING \o1SIBIUTY THROUGH SMOKE 

METHOD OFJIN 

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18-15

Example Problem 18.11-3

Problem Statement

An inspector finds 5 lbs of PVC pipe in a compartment 10 ft wide x 30 ft long x 12 ft high

c c c

(w x l x h ):

(a) What is the visibility to a reflecting sign given flaming combustion?

(b) What is the visibility to a reflecting sign given smoldering combustion?

Solution

Purpose:

(1) Determine the visibility under the different burning methods.

Assumptions:

(1) Complete burning within the method specified

Spreadsheet (FDT ) Information: s

Use the following FDT :

s

(a) 18_Visibility_Through_Smoke.xls

FDT Input Parameters: s

c

-Compartment Width (w ) = 10 ft

c

-Compartment Length (l ) = 30 ft

c

-Compartment Height (h ) = 12 ft

-Mass of fuel burn = 5 lbs

-Select PVC

-Select Reflecting Signs

-Select Flaming Combustion (get result)

-Select Smoldering Combustion (get result)

Results*

Burning Method Visibility

Flaming .34 ft (0.10 m)

Smoldering .60 ft (0.18 m)

*see spreadsheet on next page
18-16

Spreadsheet Calculations

(a) FDT : 18_Visibility_Through_Smoke.xls s

CHAPTER 18. ESTIMATING VISIBILITY THROUGH SMOKE 

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18-17

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18-18

(b) FDT : 18_Visibility_Through_Smoke.xls s

CHAPTER 18. ESTIMATING VISIBILITY THROUGH SMOKE 

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18-19

ESTIMATING \o1SIBIUTY THROUGH SMOKE 

METHOD OFJIN 

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A-1

APPENDIX A. NUCLEAR POWER PLANT

ELECTRICAL CABLE FUNDAMENTALS

A.1 Introduction

The function of electrical cable is to provide a medium for transmitting electrical energy (power

control or signals) between two points in a common electrical circuit, while simultaneously

maintaining the electrical isolation of the transmission path from other elements of the same circuit

and from other co-located circuits. Cable failure, therefore, implies loss of continuity in the energy

transmission path or diversion of a sufficient fraction of the available electrical energy to an

unintended circuit destination such that proper function of the circuit is no longer assured. A typical

boiling-water reactor (BWR) requires approximately 97 km (60 miles) of power cable, 80.5 km

(50 miles) of control cable and 402 km (250 miles) of instrument cable. A pressurized-water reactor

(PWR) may require far more, as illustrated by the containment building of Waterford Steam Electric

Generating Station, Unit 3 which required nearly 1,609 km (1,000 miles) of cable (NUREG/CR-6384).

The majority of fire dynamics, fire risk evaluations will focus on electrical cables because of their

thermal fragility. It is therefore necessary to have a fundamental understanding of electrical cables.

Fire can cause cable failures in several ways. Experience from actual fire events has shown that

different modes of fire-induced failures in electrical cables can in turn, produce a variety of circuit

faults, leading to a range of circuit faulting behaviors. The risk implications of a given circuit fault

depend upon the associated component function.

This appendix describes the types of cables commonly encountered in nuclear power plant (NPP)

applications and the modes of cable failure that might be observed. It also discusses the potential

impact of various cable failure modes on power, control, and instrumentation circuits. In addition,

this appendix identifies the factors that can influence the potential for each of the identified cable

failure modes that may result from a fire. Because of the large quantity of cable in a typical NPP

and the fact that much of the cable material (e.g., polymer insulation and outer jacket) is

combustible, cables frequently comprise a significant fraction of the total combustible load in many

areas of an NPP.

The fire at Browns Ferry Nuclear Power Plant (BFNP) Unit 1, provides the classic example of how

loss of function and spurious signals can occur as a result of a cable fire (NRC Bulletin BL-75-04).

As such, it represents one of the most serious events ever experienced at a U.S. commercial NPP.

In that fire, which was initiated by a candle flame igniting polyurethane foam in an improperly sealed

penetration, temperatures as high as 816 °C (1,500 °F) caused damage to more than 1,600 cables

routed in 117 conduits and 26 cable trays. Of these, a large number were safety-related. The

number of damaged safety-related cables can be categorized by Unit as: 482 from Unit 1, 22 from

Unit 2, and 114 common to both units. As a result, the reactor lost control power to a significant

amount of emergency core cooling system (ECCS) equipment. In fact, at one point in the event,

all power to Unit 1 ECCS motors and valves was lost.
A-2

Furthermore, fire-induced short circuits caused many instrument, alarm, and indicating circuits to

provide false and conflicting indications of equipment operation, thereby impeding operators’ ability

to control reactor safety functions. For example, one panel indicated that all ECCS pumps were

operating, while another panel indicated that there was no need for this operation. The fire was

contained to a relatively small interior area of the plant [the cable spreading room (CSR) and Unit 1

reactor building] and the conditional core damage probability, for the event has been estimated

to be about 0.4 (NUREG/CR-2497, “Precursors to Potential Severe Core Damage Accidents:

1969–1979, A Status Report,” Volume 1 and 2).

The most intense part of the fire, which involved burning stacks of horizontal cable trays, covered

an area roughly 3.3 m (10.9 ft) by 2.5 m (8.2 ft) in dimension. Because of reluctance to use water,

fire suppression was considerably delayed, and the fire burned some 7 hours after it started.

A.2 Electrical Cable Construction

Cables come in a wide variety of configurations. The primary configuration features that define a

given cable are the size of the individual conductors [expressed using the American Wire Gauge

(AWG)], the number of conductors, shielding and/or armoring features, and the insulation/jacket

materials used.

Of the materials available for use as cable insulation and jacketing, the broadest categories are

thermoplastic and thermoset. Thermoplastic materials melt when heated and solidify when cooled.

Thermoset materials do not melt, but do begin to smolder and burn if sufficiently heated. In

general, thermoset materials are more robust, with failure temperatures of approximately 350 °C

(662 °F) or higher. Thermoplastic materials typically have failure temperatures much lower than

218 °C (425 °F), where failure is typically associated with melting of the material.

Cables typically consist of one or more metallic conductors, insulation, filler, shielding, sheaths, and

jacket. Each metallic conductor (generally copper or aluminum) is electrically isolated by being

encased in a layer of insulation. The insulation, which is often considered the single most important

component of the cable is typically made from a dielectric material (e.g., plastic, rubber, polymeric,

silicone-based, or rubber-based material of some type). The term “sheath” commonly refers to an

aluminum or steel jacket, rather than rubber or plastic (e.g., armored sheathed cable). Some

cables may also include one or more shields consisting of metallic tape, composition tape, or a

metallic braid. The shield is wrapped around the insulated conductors under the jacket or sheath.

Single or multiple insulated conductors with their associated shields and sheaths are grouped

together within a single integral protective jacket. The jacket serves a strictly utilitarian purpose

(physical protection) and has no electrical function.

Cable jackets are typically constructed of rubber or plastic materials. The purpose of the jacket is

to provide the insulated conductor(s) with physical or environmental protection, and/or increased

flame retardancy. Cable jackets designed for increased flame retardancy slow the flame spread

across the jacket and reduce the fuel contribution from the cable once ignited. Nevertheless,

having increased flame retardancy does not ensure functionality.
A-3

Insulation plays an essential roll in a cable’s overall performance at normal and elevated

temperatures. The function of insulation is to electrically separate each conductor from the other

conductors and from the ground plane. In some cases, cable jackets and cable insulation are

constructed of the same materials. The number of insulated conductors within a cable is commonly

identified as follows:

• single-conductor cable (1/C)

• multi-conductor cable [e.g., 2 conductors (2/C), 7 conductors (7/C)]

• triplex-conductor (triple-conductor) cable (3/C)

Cables are also identified by their rated power voltage as shown in Table A-1 (Salley, 2000).

Table A-1. Designation of Electrical Rated Voltages

Designation Voltage

Low Up to 600 V

Medium 601 to 15,000 V

High* 15,001 V and greater 

* High voltage cables are typically not found inside the NPP. 

 They may be used as a cable bus in trenches, or in the switchyards.

A.3 Description of Cables

NPPs use three functional types of cables for power, control, and instrumentation. Virtually every

system in an NPP depends on the continued operation of one or more electrical cables. Power

cables may be single-conductor, multi-conductor, or triplex. Control and instrumentation cables are

generally of a multi-conductor design.

As the name implies, a single-conductor cable is a single insulated metal conductor that typically

has an integral over-jacket. A triplex cable is a grouping of three signal-conductors that are

manufactured together and are often twisted around a centrally located uninsulated core wire,

which may be connected to the circuit ground. Basic electrical construction and configurations are

illustrated in Figure A-1.
A-4

Figure A-1 Basic Electrical Cable Construction —

Common Single- and Multi-Conductor Arrangements
A-5

Multi-conductor cables are more varied and may come with virtually any number of conductors

limited only by practical considerations such as overall physical diameter and handling ability. The

most common configurations encountered in a NPPs are 2/C, 3/C, 7/C, and 12-conductor

configurations. The 3/C, 7/C, and 12-conductor configurations are popular with manufacturers

because they result in an overall cable product that maintains an essentially round outer profile.

Another common configuration, particularly for instrument cables, involves some number of

twisted/shielded pairs within a protective jacket. In this case, the shield refers to a conductive wrap,

such as a metal foil, wrapped around, conductor pairs. This is common in sensitive instrument

circuits where stray electromagnetic or radio-frequency interference (EMI/RFI) may be a concern.

These cables are also commonly used in communication systems.

The size of a cable is generally expressed as the number of conductors and the AWG of the

individual conductors. Hence, a 3/C 12 AWG cable is a 3-conductor 12-gauge cable. Power cables

typically range from relatively small 12 AWG cables (equivalent to cables used in residential

applications for household power circuits) through very large cables in which the conductor

diameter can approach or even exceed 2.54 cm (1 inch) (note that a higher gauge number indicates

a smaller conductor.) For power cables, the size selection is generally based on the ampacity

(current-carrying capacity) required in a specific application.

Control cables are generally of a smaller gauge, commonly range from 16 AWG through 10 AWG

with exceptions on the upper end of the size range. Instrumentation cables are generally of

16 AWG or smaller.

Voltage levels will also vary with the application. Instrument circuits generally use low voltages

(50 volts or less). Control circuits are commonly in the 120–250-volt range. Power circuits

encountered within an NPP generally range from 120 to 4,160 volts, with offsite power circuits

ranging to 15 kV or higher.

Cables are generally routed through the plant in horizontally raceways (generally trays or conduits)

with vertical runs as required between different elevations in the plant. The cables are generally

segregated by type (power, control, and instrumentation) but cables of various voltages and

functions can be found together in some plants (generally older plants). High-voltage power cables

are typically routed by themselves and may use maintained spacing to address ampacity concerns.

Under maintained spacing, cables are not stacked and each cable is individually strapped to the

electrical raceway. Gaps between cables ensure that they do not come into physical contact with

each other. For most cables, random placement within the tray is common (that is, the cables are

simply laid into the tray in a more or less random manner).
A-6

Fire exposure of an electrical cable can cause a loss of insulation resistance, loss of insulation

physical integrity (i.e., melting of the insulation), and electrical breakdown or short-circuiting. Fireinduced damage to a cable can result in one of the following electrical conductor failure modes

(LaChance et al., 2000):

• An open circuit results in a loss of electrical continuity of an individual conductor

(i.e., the conductor is broken and the signal or power does not reach its destination).

• A short to ground is experienced when an individual conductor comes into electrical contact

with a grounded conducting medium (such as a cable tray, conduit, or a grounded

conductor) resulting in a low-resistance path that diverts current from a circuit. The fault

may be accompanied by a surge of excess current to ground (particularly in higher voltage

circuits) that is often damaging to the conductor.

• A hot short is characterized by electrical faults that involve an energized conductor

contacting another conductor of either the same cable (a conductor-to-conductor hot short)

or an adjacent cable (a cable-to-cable hot short). A hot short has the potential to energize

the affected conductor or to complete an undesirable circuit path.

It is important to note that a cable may have any number of conductors as discussed above and

it is possible for more than one conductor failure mode to be active at a given time. For example,

one set of three conductors may be shorted together (conductor-to-conductor hot short), while a

fourth conductor shorts to ground.

Both shorts to ground and hot shorts may be manifested in the form of a low-impedance fault (often

referred to as a bolted or dead-short) or as a high-impedance fault between the conductors. These

two modes of shorting are distinguished on the basis of the following considerations:

• A high-impedance fault may allow power to pass from one conductor to another (or to

ground) even between circuits with dissimilar voltages, while a low-impedance short

between circuits of dissimilar voltage or between a circuit and ground often trips circuit

protection features (fuses or breakers) in one or both circuits.

• A single low-impedance short in a power circuit typically trips the lowest level of upstream

circuit protection, while multiple high-impedance faults may trip a higher-level circuit

protection feature (if circuit protection coordination is not provided), leading to loss of a

higher-level electrical bus.

• A high-impedance fault in an instrumentation circuit may lead to a biased indication that

might not be detected by operators, while low-impedance shorts typically result in a more

easily detectable situation (e.g., complete loss of indication or an indication at the extreme

high or low scale).
A-7

A.4 Cable Materials

For fire risk analysis, cable insulation and jacket materials can be separated into two broad

categories, as discussed in the following subsections.

A.4.1 Thermoplastic Materials

Thermoplastic materials are defined as high molecular weight polymers that are not cross-linked

and are generally characterized by the distinct melting point of the insulation material.

Thermoplastic materials can be repeatedly softened by heating and hardened by cooling within a

temperature band that is a physical property of the material. This property is a function of the loose

molecular bonding of the material. Some thermoplastic materials have a low melting point, which

can be a disadvantage in that melting insulation can lead to conductor failures (e.g., conductor-toconductor shorts and conductor-to-ground shorts) at relatively low temperatures. Some

thermoplastic insulations are also problematic in that they produce dripping, flaming fires after

ignition. Cables using thermoplastic insulation are not usually qualified to survive the full

environment qualification exposure condition of IEEE Std. 383. Many thermoplastic cables will

however, pass the limited flame spread test included in the IEEE Std. 383.

Thermoplastic insulation is generally easy to manufacture and economical to use. Common

thermoplastic insulations include cellular; low and high polyethylene (PE); polyvinyl chloride (PVC);

polyurethane; polypropylene (PPE); nylon; chlorinated polyethylene (CPE); tetrafluoroethylene

(TFE), Teflon, and fluorinated polymers such as DuPont’s TFE copolymers with ethylene (known

as Tefzel ), DuPont’s PFA (perfluoroalkoxy branched polymers), Allied Chemical’s Halar (ethylene ®

copolymer with chlorotrifluoroethylene), and Dynamit Nobel’s Dyflor (polyvinylidene fluoride).

Figure A-2 shows typical thermoplastic (PVC) insulated cable construction. In general, cables that

do not pass IEEE 383 rating (i.e., non-IEEE qualified) are thermoplastic.

Figure A-2 Thermoplastic Insulated Cable Construction
A-8

A.4.2 Thermoset Materials

The molecular consist of chains that are tied together with covalent bonds in a network

(crosslinked). Thermoset insulations are generally characterized as softening, but not melting,

during higher-than-normal temperature exposures. While they soften, they tend to maintain the

mechanical properties of the insulator. As a result, thermoset insulations generally exhibit better

low-and-high temperature properties, thermal aging resistance, and overload resistance than

thermoplastic insulations. Thermoset materials are vulcanized by heat (or other methods) during

their fabrication process. As such, the materials are substantially infusible and insoluble. The

molecular structure is tightly interlocked (in contrast to thermoplastic insulations). Common

thermosetting insulations include ethylene propylene rubber (EPR); crosslinked polyethylene

(XLPE); DuPont’s Hypalon (chlorosulphonated polyethylene); nitrile or rubber butadiene nitrite

(NBR); styrene butadiene rubber (SBR); polybutadiene; neoprene; and silicone rubber. Cables

using thermoset insulation are usually qualified to IEEE Std. 383. In general, cables that do pass

IEEE 383 rating (i.e., IEEE 383 qualified) are thermoset cables.

In summary, thermoplastic materials are high molecular weight polymers that are not cross-linked,

while the polymer chain of thermoset materials are crosslinked in covalent bonded networks. When

thermoset resins are heated during manufacture, from ambient to upward of 232 °C (450 °F), they

undergo an irreversible chemical reaction, referred to as “curing” or “polymerization,” to make the

final cross-linked thermoplastic product. While thermoplastic materials can be reshaped by heating

and cooling within the proper temperature ranges for the materials, thermoset materials cannot be

reshaped once they have been crosslinked. Figure A-3 shows typical thermoset (XLPE) insulated

cable construction.

Figure A-3 Thermoset Insulated Cable Construction
A-9

A.5 Cable Failure Threshold and Time to Damage

A.5.1 Theory

In a very basic, first order analysis, one can assume thermal damage occurs the instant the target

reaches its minimum failure temperature. For example, if the target is an electrical cable and it is

known that the cable fails at 425 °F (218 °C), the analyst can assume failure as soon as the cable

is exposed to a 425 °F (218 °C) hot gas layer. However, there are more realistic methods of

analysis.

We know from thermal detector and sprinkler response (see Chapter 12), that all materials have

a mass that must be heated before they can reach a target temperature. This thermal inertia is

quantified as the response time index (RTI) for detection and suppression devices and the same

principle applies to electrical cables, however with a number of complications. For example, is the

cable in free air (e.g., air drop) conduit or in a cable tray? Where is the cable located in the cable

tray; top, bottom, against a side rail, or in the center of the cable mass? Does the cable have any

fire retardant coating? If so, which brand? These are just a sampling of the possible variables that

complicate the thermal impact on a cable. At this writing, many of these factors are unknown;

however, we can use what information is currently available to provide a much more accurate

method of determining cable failure threshold and time to damage. The following information was

developed by the authors in conjunction with Mr. Steve Nowlen of Sandia National Laboratories for

use in fire protection risk analysis by the NRC.

A.5.2 Temperature Thresholds — Thermoset Cables

Thermoset represents a very broad class of cables. Of the thermoset cables, crosslinked polyolefin

(XLPO) insulated cables are generally the weakest in this cable family in terms of susceptibility to

thermal damage (see discussion of Kerite FR below). Of the general class XLPO, the specific

material crosslinked polyethylene (XLPE) is the most widely used. XLPE-insulated cables are used

extensively in the U.S. nuclear power industry. For example, based on surveys of nuclear industry

practices conducted in support of the NRC’s Equipment Qualification research programs, one of

the most popular cable products is the widely used Rockbestos Firewall III line of nuclear qualified

cable products. In general, the XLPO and XLPE cables can be taken as representative of the

weaker thermoset materials. Fairly extensive evidence for thermal damage to thermoset cables

in general, and the XLPO and XLPE materials in particular, exists based on a number of public

sources.

Perhaps the earliest source of direct evidence on thermal failure thresholds for thermoset cables

is provided in NUREG/CR-5384 which reports thermal damage test results from the early 1980's

for an XLPE-insulated cable. The tested cable was specifically IEEE-383 qualified, including the

flammability testing protocol. The samples were taken from excess stocks of cables purchased to

support NRC-sponsored testing in the late 1970s. Hence, these cables are a very early vintage

IEEE-383-qualified cable given that the flame spread test was first introduced in IEEE-383 in the

1975 revision. During high temperature exposure tests, electrical failures were observed at

temperatures as low as 518 °F (270 °C). At this temperature damage times were relatively long

ranging from 30 to 82 minutes, and averaging 56 minutes. At an exposure temperature of 662 °F

(350 °C) the damage times ranged from 7 to 28 minutes, averaging 13 minutes.
As reported by M.H. Salley in “An Examination of the Methods and Data Used to Determine 1

Functionality of Electrical Cables when Exposed to Elevated Temperatures as a Result of a Fire

in a Nuclear Power Plant,” University of Maryland, MS Thesis, 2000.

A-10

Direct evidence is also provided in NUREG/CR-5546 (1991) which reports thermal damage results

for a XLPE-insulated Rockbestos Firewall III cable, an extremely common cable in the U.S. nuclear

industry. At a temperature of 617 °F (325 °C) no failures were observed for two samples during

exposures lasting approximately 80 minutes. At 626 °F (330 °C) failures were observed in all four

samples tested. The failure times ranged from 33 to 79 minutes, and averaged 55 minutes. At a

temperature of 635 °F (335 °C), damage times ranged from 16 to 30 minutes and averaged about

20 minutes.

A third source of direct evidence is gained from superheated steam exposure tests conducted

under severe accident simulation tests in the equipment qualification (EQ) domain (e.g.,

NUREG/CR-5655, 1991). The dry superheated steam environments look much like the dry hot

environment of a fire, and a previous study has concluded that these results might be applied as

indicators of fire damage thresholds as well (SAND92-1404C). A direct correlation has been made

between the damage criteria applied in fire testing to those applied in the EQ tests. All products

tested were explicitly qualified for use in U.S. nuclear industry applications. Interpretation of the

EQ test results requires selection of a failure criterion. NUREG/CR-5655 reports results for four

separate failure criteria, each representing a progressively more severe level of degradation. Using

the worst case failure threshold (i.e., that indicative of the highest level of degradation), the failure

threshold for an XLPE cable was estimated at about 610 °F (320 °C). For the more general class

of XLPO materials, failures at the same threshold were noted at temperatures as low as 572 °F

(300 °C).

A fourth source for direct evidence on the electrical performance of XLPE-insulated cables is a

series of tests performed in 1984 by TVA . The TVA tests involved six different cable types each 1

insulated with XLPE. The maximum temperature reached by the cables during the test was 570 °F

(299 °C) at the end of a 1-hour exposure protocol. None of the XLPE cables experienced electrical

failure at these temperatures.

A fifth source of direct evidence regarding failure for thermoset cables is the recently completed

NEI/EPRI Cable Failure Modes and Effects Tests. As a part of an expert panel activity (EPRI

TR1006961) some panel members examined the cable failure data in the context of temperature,

and estimated the minimum failure threshold for the thermoset cables tested. Each panelist was

left to their own approach to analysis and interpretation of the test data, and each reached

somewhat different conclusions. Furthermore, the cable types (insulation material in particular) are

not identified beyond thermoset versus thermoplastic. Nonetheless, the results do provide some

insights into cable failure thresholds for at least some cable types as follows:

• Mowrer noted thermoset cable failures at a minimum temperature of 680 °F (360 °C).

(See pg. B-21 of the EPRI TR1006961.)

• Funk concluded that, for thermoset cables, 550 °F (288 °C) was a “reasonably conservative”

estimate of the “threshold of thermal insult below which cable failure (either partial or

complete) does not occur, or is extremely unlikely.” (See pg. B-3, ibid.)

• Salley noted at least one thermoset cable that failed at a temperature of 591 °F (311 °C)

and others in the range of 660–680 °F (349–360 °C). (See pg. B-64, ibid.)
Various thermoplastic materials will pass the flame spread portion of the IEEE-383 test, but not 2

electrical performance requirement of the LOCA portions of the testing protocol. Such cables

would not be considered “IEEE-383 qualified” in this context.

A-11

The Fire Performance of Electrical Cables (FIPEC) study provides indirect evidence based on the

piloted ignition thresholds. The reported ignition temperatures for a range of XLPE cable products

ranged from 429-885 °F (220-474 °C). The average ignition temperature reported was 630 °F

(332 °C). The results again illustrate a wide variability in performance. However, ignition behavior

is dominated by the outer jacket material, rather than the cable insulation material. The FIPEC

cable samples involved a range of jacket materials, and many of these were PVC-based

thermoplastic materials. Hence, the lower threshold values cited might be more an indication of the

performance of the thermoplastic jackets than of the thermoset insulation. Note that in the U.S.

nuclear industry it is not common practice to utilize thermoplastic or PVC jackets on a thermosetinsulated cable. Rather, thermoset cables will typically have neoprene, rubber-based, or chlorosulfanated polyethylene (hypalon) jackets. These materials are all thermoset.

It is worth noting that in the IPEEEs, a commonly applied screening failure threshold for IEEE-383

qualified cables applied by licensees was 700 °F (370 °C). Note that IEEE-383 involves both LOCA

electrical performance testing and a flame spread test. Virtually all cables fully qualified to both

aspects of the IEEE-383 test standard are thermoset materials. The 700 °F (370 °C) value is 2

recommended in the EPRI FIVE method (EPRI TR-100370), and appears again in the EPRI Fire

PRA Implementation Guide (EPRI TR-105928). The original source cited for this value is the EPRI

cable damage tests reported in a series of Factory Mutual Research Corporation (FMRC) studies

from the early 1980s (see in particular, EPRI NP-1767, March 1981). The method used to estimate

the cable “critical” threshold values cited in the original FMRC work, and repeated in FIVE, has

since been discredited, and has been disavowed by FMRC (see letter from A. Tewarson of FMRC

to R. Kasawara of EPRI, dated May 10, 1995). There appears little basis for the continued reliance

on 700 °F (370 °C) as a screening threshold for thermoset/qualified cables given the direct

evidence of failures at substantially lower temperatures for a broad and common class of

thermoset/qualified cable products.

Suggested Method for Evaluating Generic Thermoset Cables: A failure threshold of 625 °F

(330 °C) is recommended for the generic class of thermoset cables.

Summary of Basis

• The recommended SDP practice does not bound all of the data on cable failure

thresholds for all thermoset cable types. In particular, it does not bound the

performance of some XLPO cable types (e.g., Polyset) and it does not bound one

specific test data point related to XLPE. It also does not bound the proprietary

material “Kerite FR” (see discussion below).

• Given their widespread use in the U.S. nuclear industry, failure thresholds for

thermoset materials are based on XLPE-insulated cables.

• 330 °C is representative of clearly demonstrated and documented test results

showing failures within an average time of well under one hour for a widely used

specific XLPE-insulated cable product, Rockbestos Firewall III.
A-12

• The lower threshold values implied by the earlier tests in NUREG/CR-5384 are not

recommended for this application given the relatively long failure times reported

(average time of nearly one hour) and the very early vintage of the cables tested.

The TVA results also provide evidence that the failure thresholds for most XLPE

cables should be expected to exceed 570 °F (299 °C).

• The lower threshold values associated with the specific XLPO cable product tested

in NUREG/CR-5655 is not recommended as a general criterion because this

particular material/product is not widely used as an insulation material in the U.S.

nuclear industry.

• It is recommended that the consideration of higher threshold values based on

knowledge of a specific cable product being used in a specific case should be

deferred to the Phase 3 analysis should such an analysis be pursued.

Special Exception: There is a particular proprietary cable insulation material called “Kerite FR.”

While this material is a thermoset, experimental evidence suggests it is substantially more

vulnerable to thermal damage than are other thermoset materials. In particular, NUREG/CR-5655

reports substantial degradation of the cable’s insulation value at temperatures as low as 307 °F

(153 °C). Testing by SCE&G cites average temperatures at failure of 458 °F (237 °C) (as reported

by Salley). Hence, it is recommended that the material Kerite FR should be analyzed using the

failure criteria for a thermoplastic cable, not the values reported for a thermoset material.

A.5.3 Temperature Thresholds — Thermoplastic Cables

The typical thermoplastic cable is polyethylene-insulated (PE) often with a polyvinyl-chloride (PVC)

jacket. This configuration is also considered representative of the weaker members of the

thermoplastic group. The evidence for thermal failure threshold for PE-insulated cables can be

taken from a number of sources.

Direct evidence of thermally induced electrical failure is provided in NUREG/CR-5384 (see

Figure 6.3 in that reference). The failures for this cable were observed at temperatures as low as

482 °F (250 °C). At this exposure temperature, failure times ranged from 1.5 to 23.5 minutes and

averaged about 9 minutes. At exposures of 356 °F (180 °C) no failures were observed in six test

samples during two separate tests with exposures lasting approximately two hours. Given the

relatively short failure times observed in some of the 482 °F (250 °C) exposure tests, the actual

failure threshold likely lies somewhat below the cited 482 °F (250 °C) value, but certainly above

356 °F (180 °C).

Direct evidence of functional failure is also provided by testing conducted by Tennessee Valley

Authority (TVA). Two samples of a PE/PVC (dual layer) insulated cables tested. The failure

temperature in the first test was estimated as 346 °F (175 °C), and in the second test as 440 °F

(227 °C). During the TVA tests, weights were placed on top of the sample cables to simulate the

weight of a load of cables in a raceway. The first test utilized a load approximately 4 times larger

than the second test. During the second test, the cables were examined immediately following the

initial failure, and showed signs of substantial melting. A second series of tests in 1996

demonstrated satisfactory electrical performance for the same cable type exposed to temperatures

peaking at 282 °F (139 °C) at the end of a one-hour exposure protocol.
In this context, “qualified” refers a cable shown to pass all aspects of the IEEE-383 performance 3

standard. An “un-qualified” or “non-qualified” cable is a cable that does not meet one or more

aspects of the IEEE-383 standard. Note that a cable that has been shown to pass the IEEE-383

flame spread test but has not been shown to pass the LOCA electrical performance tests in IEEE383 is considered “un-qualified” in this context.

See FIVE Reference Table 1E (pg. 10.4-67). 4

A-13

A third source of direct evidences is testing by VTT Finland (ibid). Failures of a PVC-insulated

cable were reported at temperatures as low as 385 °F (196 °C). These results might be discounted

to some extent by the fact that these are tests of a European cable formulation, and likely a Russian

formulation (given its use in the Finish nuclear industry). Hence, its formulation in comparison to

typical U.S. material would be unknown. It is also uncommon to encounter a PVC-insulated cable

in the U.S. nuclear industry. This result is taken as a general indication of marginal performance

for these materials at temperatures exceeding 390 °F (200 °C).

A fourth source of direct evidence is the above cited EPRI expert panel report (TR1006961).

The following damage insights are noted:

• Mowrer noted thermoplastic cable failures at a minimum temperature of 400 °F (205 °C).

(See pg. B-21 of the EPRI TR1006961.)

• Funk concluded that, for thermoplastic cables, 400 °F (205 °C) was a “reasonably

conservative” estimate of the “threshold of thermal insult below which cable failure (either

partial or complete) does not occur, or is extremely unlikely.” (See pg. B-3, ibid.)

• Salley noted at least one thermoset cable that failed at a temperature of 390 °F (200 °C)

and recommended a threshold value of 400 °F (205 °C) for “garden variety thermoplastic

cables.” (See pg. B-64, ibid.)

Indirect evidence is provided based on the FIPEC piloted ignition thresholds. The minimum

temperature reported for piloted ignition of a PE/PVC cable was 388 °F (197 °C) for one sample.

All other samples showed ignition temperatures of 476 °F (246 °C) or greater. The average

temperature for piloted ignition for the six cable types tested was 487 °F (253 °C).

It is worth noting that the EPRI FIVE method (EPRI TR-100370) recommended use of a failure

threshold for non-qualified cables , generally corresponding to thermoplastic cables, of 425 °F 3

(218 °C) . This value was widely used by licensees in their IPEEE analyses. The basis for the 4

value is not explicitly cited in the FIVE documentation. The value appears in Reference Table 1E

(pg. 10.4-47).
A-14

Recommended SDP practice: Continue the use of the commonly applied IPEEE failure threshold

of 205 °C (400 °F) for non-qualified or thermoplastic cables.

Summary of Basis:

The recommended value is based on the available experimental evidence for PE and PVCinsulated cables.

• A value of 482 °F (250 °C) is known to yield damage times of on the order of 2-20

minutes.

• The TVA results for the heavily weighted cables in their first test can be discounted

to some extent as being a grossly conservative loading configuration. However, the

observation of cable failure at 346 °F (175 °C) does provide evidence of marginal

performance at these temperatures.

• The loading configuration in the second TVA test cannot be discounted and yielded

failures at 440 °F (227 °C) in an exposure of well under 1-hour duration.

• The recommended value is largely consistent with the piloted ignition results for the

FIPEC study excluding only one test sample with a disproportionately lower ignition

threshold.

A.5.4 Radiant Heating Failure Criteria — Cables

The available data for the electrical failure of cables under radiant heating conditions remains

relatively sparse. While substantive data is available for higher heat flux conditions, the threshold

conditions in particular have only been explored directly in a handful of cases.

The primary source of direct evidence is EPRI-sponsored tests conducted at Factory Mutual

Research Corp. during the late 1970s and early 1980s (see for example, EPRI NP-1200). These

tests involved a fairly wide range of NPP cable products. Unfortunately, the threshold exposure

levels were only explored in a limited number of cases, and were extrapolated for most tests. The

extrapolation method used in the data analysis has since been discredited.

There was also a limited set of early NRC-sponsored radiant exposure tests at Sandia National

Laboratories in the late 1970s (see NUREG/CR-5384). These tests were conducted in a manner

similar to the EPRI tests, but at a more representative scale using a loaded cable tray.

Some additional insights were gained from the FIPEC study. The FIPEC study involved primarily

thermoplastic cables and focused on ignition properties with no direct monitoring of electrical failure.

However, the ignition of a cable is taken as indirect evidence that electrical failure is imminent.

Hence, these data are taken as indicators of threshold, but not timing (see discussion of failure

timing).

Finally, current PRA practice as documented in the EPRI FIVE methodology and in the more recent

EPRI Fire PRA Implementation Guide, was considered.

Based on the available information, threshold heat flux damage limits of 0.5 BTU/ft s (6 kW/m )

2 2

have been recommended for thermoplastic cables. For thermoset cable the recommended damage

threshold is 1.0 BTU/ft s (11 kW/m ). 2 2
A-15

Figure A-4 Raw Time to Damage Chart for Thermoset XLPE

Cables

A.5.5 Basis for Cable Damage Timing Estimates

The data sources available to support the assessment of cable damage times are essentially

identical to those described in the discussion of cable damage thresholds. The specific objective

here is to estimate the damage time for a given exposure condition at or above the damage

threshold. The following describes how the recommended damage time estimates were developed.

A.5.6 Temperature Exposures — Thermoset Cables

Damage timing for thermoset cables is based primarily on the data reported in NUREG/CR-5546

for XLPE-insulated cables (the Rockbestos Firewall III product). As previously discussed, the use

of XLPE as representative of the thermoset class does not bound all of the thermoset products (see

discussion of Polyset) but does bound the vast majority of thermoset products. XLPE is also the

most popular single product used in the U.S. nuclear industry.

A review of the NUREG/CR data also showed that they were broadly consistent with more recent

tests, including in particular the recent EPRI/NEI circuit failure tests (EPRI TR-1003326). The

EPRI/NEI tests often involved temperatures very near the expected threshold of cable damage.

Hence, the damage times were relatively prolonged, often in excess of 1 hour. This is consistent

with the NUREG/CR data in that the damage times at the threshold temperature were also in

excess of 1 hour. Hence, use of the specific information in the NUREG/CR appears appropriate.

These data are plotted in two figures. Figure A-4 shows the direct time to failure versus exposure

temperature as directly recorded in the tests. In order to extrapolate between the recorded data

points, the data are re-plotted as shown in Figure A-5.
A-16

Figure A-5 Time to Damage Plot for Thermoset Cables

with Linear Regression Curve

In this second plot the exposure temperature is plotted against the inverse of the time to failure.

This inversion provides a near-linear relationship between the exposure temperature and the

inverse of time to damage. This relationship is characterized by the following linear regression curve:

1/(time to damage : seconds) = 3.343E-05 ×(Temp: °C) - 1.044E-02

Using this relationship, a table of time to damage values was generated as previously presented.

Note that the results of the linear regression were adjusted modestly for values that fell outside the

data range where extrapolation is necessary. Also note that for the purposes of SDP analysis, the

maximum damage times (at the threshold) were limited to 30 minutes. Table A-2 provides a time

vs. temperature relationship for thermoset cables.

Table A-2. Failure Time-Temperature Relationship for Thermoset Cables

Exposure Temperature Time to Failure (minutes)

°C °F

330 625 28

350 660 13

370 700 9

390 735 7

410 770 5

430 805 4

450 840 3

470 880 2

490 (or greater) 915 (or greater) 1
A-17

Figure A-6 Raw Time to Damage Plot for Thermoplastic

PE Cables

A.5.7 Temperature Exposures — Thermoplastic Cables

Damage timing for thermoplastic cables is, again, based primarily on the data reported in

NUREG/CR-5384 for PE-insulated cables. These data were analyzed in a manner similar to that

used in the analysis of the Thermoset cable response as discussed above. However, in the case

of the thermoplastic cables, there was considerable scatter in the data. In particular, very short

damage times are reported for some cases at the lowest exposure temperatures. The reasons for

this scatter are not clear.

The data used in the analysis are again shown in two figures essentially identical to those

discussed in the thermoset section above. Figure A-6 shows the direct time to failure versus

exposure temperature as directly recorded in the tests for those cases used in the analysis.

Figure A-7 shows the inverse of the time to failure - temperature relationship.
A-18

Figure A-7 Time to Damage Plot for Thermoplastic Cables

with Linear Regression Curve

Using a similar analysis approach, the following linear regression curve was obtained:

1/(time to damage : seconds) = 3.488E-05 ×(Temp: °C) - 7.467E-03

Using this relationship, a table of time to damage values was generated. Again, results of the linear

regression were adjusted for values that fell outside the data range where extrapolation is

necessary. Table A-3 provides a time vs. temperature relationship for thermoplastic cables.

Table A-3. Failure Time-Temperature Relationship for Thermoplastic Cables

Exposure Temperature Time to Failure (minutes)

°C °F

205 400 30

220 425 25

230 450 20

245 475 15

260 500 10

275 525 8

290 550 7

300 575 6

315 600 5

330 625 4

345 650 3

355 675 2

370 (or greater) 700 (or greater) 1
A-19

A.5.8 Radiant Exposures — Thermoset and Thermoplastic Cables

As previously noted, the available data for radiant exposure of cables is less complete than that for

convective exposures. Most radiant heat tests have been conducted at relatively high heat flux

levels, often representative of flashover conditions. This leads to relatively short damage times.

The available tests generally reported damage times ranging from as short as a few seconds up

to no more than 5–10 minutes. Fire risk analysis is also interested in marginal exposure conditions

where damage times are expected to be upwards of 30 minutes or more. Given the data

limitations, expert judgement has been applied to fill in our gaps in the understanding of radiant

heating exposure conditions and the timing of cable damage.

Tables A-4 and A-5 provided below, document the recommended cable damage time/heat flux

relationship for thermoset and thermoplastic cables.

Table A-4. Estimated Time to Damage for Radiant Heating

Exposures for Thermoset Cables

Exposure Heat Flux Time to Damage

BTU/ft s kW/m (minutes) 2 2

<1.0 <11 No Damage

1.0 11 19

1.2 14 12

1.4 16 6

1.6 18 1

1.75 or greater 20 or greater 1

Table A-5. Estimated Time to Damage for Radiant Heating

Exposures for Thermoplastic Cables

Exposure Heat Flux Time to Damage

BTU/ft s kW/m (minutes) 2 2

<0.5 <6 No Damage

.5 6 19

.7 8 10

0.9 10 6

1.0 11 4

1.25 14 2

1.4 or greater 16 or greater 1
A-20

A.6 References

LaChance, J., S.P. Nowlen, F. Wyant, and V. Dandini, “Circuit Analysis-Failure Mode and

Likelihood Analysis,” A Letter Report to USNRC, Sandia National Laboratory, Albuquerque,

New Mexico, ADAMS Accession #ML010450362, May 8, 2000.

BL-75-04, “Cable Fire at Browns Ferry Nuclear Power Station,” U.S. Nuclear Regulatory

Commission, Washington, DC, March 24, 1975.

Salley, M.H., “An Examination of the Methods and Data Used to Determined Functionality of

Electrical Cables When Exposed to Evaluated Temperatures as a Result of a Fire in a Nuclear

Power Plant,” Master of Science Thesis, Department of Fire Protection Engineering, University of

Maryland, College Park, Maryland, 2000.

NUREG/CR-6384, “Literature Review of Environmental Qualification of Safety-Related Electric

Cables,” Volume 1, U.S. Nuclear Regulatory Commission, Washington, DC, April 1996.

NUREG/CR-2497, “Precursors to Potential Severe Core Damage Accidents: 1969–1979, A Status

Report,” Volume 1 and 2, U.S. Nuclear Regulatory Commission, Washington, DC.

A.7 Additional Readings

Grayson, S.J., P.V. Hess, U. Vercellotti, H. Breulet, and A. Green, “Fire Performance of Electric

Cables — New Test Methods and Measurements Techniques,” Interscience Communications,

Limited, United Kingdom, 2000.

Zalosh, R.G., Industrial Fire Protection Engineering, Chapter 9, “Electrical Cables and Equipment,”

John Wiley & Sons, New Jersey, 2003.
B-1

APPENDIX B. FUNDAMENTALS OF FIRE PROTECTION

This appendix reviews some selected fundamentals and most relevant characteristics of fire

chemistry and physics (temperature, combustion products, smoke, toxicity, and fire extinguishing

agents, etc.). Those inspectors who have never been exposed to fire protection will benefit from

studying these fundamentals.

B.1 T-Squared (t ) Fire Power Law Heat Release Rate

2

B.1.1 Introduction

The primary mechanism driving the growth of a fire is the flame spreading across a fuel item or

between multiple fuel items. This growing fire will continue until one or more of the following

conditions exist(s):

• Flashover occurs and all combustible materials are involved simultaneously.

• The fire cannot spread further due to lack of combustible materials.

• The fire uses all available oxygen for combustion.

• The fire is extinguished by intervention.

B.1.2 t Heat Release Rate 2

Fire development varies depending on the combustion characteristics of the fuel(s) involved, the

physical configuration of the fuel(s), the availability of combustion air, and the influences associated

with the compartment. Once a stable flame is attained, most fires grow in an accelerating pattern,

reach a steady state characterized by a maximum heat release rate (HRR), and then enter into a

decay period as the availability of either fuel or combustion air becomes limited. Fire growth and

development are limited by factors such as the quantity and arrangement of fuel, quantity of

oxygen, and effect of manual and automatic suppression systems.

The primary parameter for describing fire growth is the HRR of the fire and how it changes with

time. The fire growth rate depends on the ignition process; flame spread, which defines its

perimeter; and the mass burning flux over the area involved. Once a combustible surface has

ignited, the fire size increases as the flame spreads across the surface or as additional items in the

room become involved. An important aspect is that the time required for the fire to grow is driven

by the ignition source and the combustible or flammable materials present.

For most materials, a local ignition eventually involves the entire fuel item by flame-spreading

processes. A typical sofa, for example, involves some combustion of horizontal, upward vertical,

and downward vertical flame spread. For furniture and commodities, this complex fire growth

process cannot be predicted by a simple formula. However, each item can have a characteristic

growth time consistent with its composition and configuration. For example, a given item is ignited,

it may achieve a heat release of 1 MW (1,000 kW) in 130 seconds, while another object might take

80 seconds. A complete mathematical description of this process is quite involved and relatively

unpredictable given the range of ignition scenarios and the complexity of describing the burning

item(s).
B-2

Nonetheless, testing has shown, that the overall HRR during the fire growth phase of many fires

can often be characterized by simple-time dependent polynomial or exponential functions

(Heskestad, 1997). The total heat release of fuel packages can be well approximated by the power

law fire growth model for both single item burning and multiple items involved in a fire. Testing has

also indicated that most growing fires can be expected to grow indefinitely until intervention by fire

fighters, and the fires have an early incubation period where fire does not conform to a power law

approximation, as shown in Figure B.1-1. That figure illustrates that following an incubation period,

the HRR of the fire grows continuously, proportional to the square of time.

Figure B.1-1 Fire Growth of t Fitted to Data 2

(Heskestad, 1997, © NFPA. With permission.)
B-3

The proposed model of the environment generated by fire in an enclosure is dependent on the

assumption that the fire grows according to the following equation:

 (B-1)

Where:

= the heat release rate (HRR) of fire (kW)

 = a constant governing the speed of fire growth (kW/sec )

2

t = the time (sec)

The proposed model of the environment generated by fire in an enclosure is dependent on the

assumption that the fire grows according to the following equation:

 (B-2)

Where:

= the rate of heat release of fire (kW)

 = a constant governing the speed of fire growth (kW/sec )

2

t = the time (sec)

The growth rate approximately follows a relationship proportional to time squared for flaming and

radially spreading fires, which are consequently called t-squared (t ) fires. Such fires are classed 2

by the speed of growth, identified as ultra-fast, fast, medium, and slow. Where these classes are

used, they are defined on the basis of the time required for the fire to grow to a heat release rate

(HRR) of 1,000 kW (1 MW). Table B.1-1 summarizes the fire intensity constant ( ) and the growth

g

time (t ) for each of these classes.

Table B.1-1. Summary of t Fire Parameters 2

Class of Fire Growth Intensity Constant

 (kW/sec )

2

Growth Time

g

t (sec)

Slow 0.00293 600

Medium 0.01172 300

Fast 0.0469 150

Ultra-Fast 0.1876 75
B-4

Figure B.1-2 plots the t fire growth rate curves that have been developed. The t relationship has 2 2

proven useful and has therefore been adopted into NFPA 72, “National Fire Alarm Code ,” to ®

categorize fires for siting of detectors as well as NFPA 92B “Guide for Smoke Management

Systems in Mall, Atria, and Large Areas,” for design of smoke control systems.

Figure B.1-2 Growth Rate Curves for t Fire (NFPA, 72 and NFPA, 92B) 2 

A t fire can be viewed as one in which the HRR per unit area is constant over the entire ignited 2

surface and the fire spreads as a circle with a steadily increasing radius. In such cases, the burning

area increases in proportion to the square of the steadily increasing fire radius. Of course, fires that

do not have such a conveniently regular fuel array and consistent burning rate might or might not

actually produce a t curve, but the t approximation appears to be close enough for reasonable 2 2

design decisions.
B-5

Figure B.1-3 provides the HRR results of various full-scale free burn tests performed at Factory

Mutual Research Corporation (FMRC) (also reported by Nelson, 1987), superimposed on the t2

HRR curves, using various standard test commodities for fuel arrays. Figure B.1-4 relates the

classes of t fire growth curves to a selection of actual fuel arrays. Figure B.1-5 plots the HRR

2

curves for various upholstered furniture items. Figures B.1-3 to B.1-5 show that the actual fire

growth curves for many common fuel arrays tend to be greater than the medium fire growth curve.

Figure B.1-3 Comparison of t Heat Release Rate with Full-Scale Free-Burn 2

Heat Release Rate (Nelson, 1987)

Figure B.1-4 Relation of t Heat Release Rate to Some Fire Tests (Nelson, 1987) 2
B-6

Figure B.1-5 Comparison of t Heat Release Rates 2

with Full-Scale Furniture Heat Release Rate

Table B.1-2 tabulates the maximum HRR for various warehouse materials. As shown, the majority

of these materials exhibit fire growth rates in the fast or ultra-fast ranges. The preponderance of

actual fire testing over the 1990's has shown that common fuel arrays exhibit fire growth rates that

tend to exceed the medium t fire growth rate. 2

Table B.1-2. Maximum Heat Release Rates of Warehouse Materials

(NFPA 72, 1999 Edition, Appendix B)

Warehouse Material

(See Notes 1 and 2)

Growth

Time

(sec) 

Heat Release

Rate ( )

(Btu/sec-ft )

2

(See Note 3)

Fire Growth

Classification

Wood pallets, stacked, 11⁄2 ft high

(6%–12% moisture) 

150–310 110 Fast-Medium

Wood pallets, stacked, 5 ft high

(6%–12% moisture) 

90–190 330 Fast

Wood pallets, stacked, 10 ft high

(6%–12% moisture) 

80–110 600 Fast

Wood pallets, stacked, 16 ft high

(6%–12% moisture) 

75–105 900 Fast

Mail bags, filled and stored 5 ft high 190 35 Medium

Cartons, compartmented and stacked 15 ft high 60 200 Fast
Table B.1-2. Maximum Heat Release Rates of Warehouse Materials

(NFPA 72, 1999 Edition, Appendix B)

Warehouse Material

(See Notes 1 and 2)

Growth

Time

(sec) 

Heat Release

Rate ( )

(Btu/sec-ft )

2

(See Note 3)

Fire Growth

Classification

B-7

Paper, vertical rolls, stacked 20 ft high 15–28 - (See Note 4)

Cotton (also PE, PE/cot, acrylic/nylon/PE), garments

in 12 ft high racks

20–42 - (See Note 4)

Cartons on pallets, rack storage, 15 ft–30 ft high 40–280 - Fast-Medium

Paper products, densely packed in cartons,

rack storage, 20 ft high 

470 - Slow

PE letter trays, filled and stacked 5 ft high on cart 190 750 Medium

PE trash barrels in cartons, stacked 15 ft high 55 250 Fast

FRP shower stalls in cartons, stacked 15 ft high 85 110 Fast

PE bottles, packed in item 6 85 550 Fast

PE bottles in cartons, stacked 15 ft high 75 170 Fast

PE pallets, stacked 3 ft high 130 - Fast

PE pallets, stacked 6 ft–8 ft high 30–55 - Fast

Methyl alcohol - 65 -

Gasoline - 200 -

Kerosene - 200 -

Diesel oil - 180 -

Notes:

(1) For SI units, 1 ft = 0.305 m.

(2) FRP = fiberglass-reinforced polyester; PE = polyethylene; PS = polystyrene;

PP = polypropylene; PU = polyurethane; PVC = polyvinyl chloride.

(3) The HRRs per unit floor area are for fully involved combustibles, assuming 100-percent combustion

efficiency. The growth times shown are those required to exceed 1,000 Btu/sec HRR for developing fires,

assuming 100-percent combustion efficiency.

(4) Fire growth rate exceeds design data.
B-8

Madrzykowski (1996), compared HRR data for office work stations with standard t HRR fire curves. 2

Figure B.1-6 shows the HRR time history of the fire growth of a three-sided office work station

compared to t fire curves. Notice how the fire begins as a slow-medium growth rate fire, and then 2

the slope increases to be representative of a fast-ultra-fast fire. As shown in Figure B.1-6, one can

use the t fire growth model to determine the HRR of similar fuel packages. 2

Figure B.1-6 Three-Sided Work Station Heat Release Rate Curve

Compared with t Curves (Madrzykowski, 1996) 2
B-9

Figure B.1-7 shows the relationship between t fire curves and six 1.2-m (4-ft) high stacks of mixed 2

wooden pallets (8 to 9 pallets per stack) arranged in two rows of three stacks, with the three stacks

in each row forming an unbroken line with 100-mm between the front and back rows. Figure B.1-7

shows that both tests exhibited there was an incubation period following which the fire growth rate

was approximately parallel to the t fast fire growth curve. 2

Figure B.1-7 Heat Release Rate Curve for Idle Pallets Compared with t Curves 2

(Garred and Smith, 1999, Interscience and Interflam. With permission.)
B-10

Figure B.1-8 shows the relationship between t fire curves and six 12-m (4-ft) high stacks of 2

cardboard boxes arranged in two rows of three stacks, with no gaps between the stacks. The boxes

were ignited by setting light to a ball of crumpled newspaper pushed 100 mm under the front of the

central stack in the front row of the array. Figure B.1-8 shows that both tests exhibited a long

incubation period, as the ball of newspaper proved to be slow burning. However, the fire did break

into the boxes immediately above the ignition source, and the flames eventually burst from the front

of those boxes and then rapidly up the front of the central (ignition) stack. Thereafter the fire growth

rate was similar to the ultra-fast t fire curve. 2

Figure B.1-8 Heat Release Rate for Stacked Box Fires Compared with t Curves 2

(Garred and Smith, 1999, Interscience and Interflam. With permission.)

B.1.3 References

Garred, G., and D.A. Smith, “The Characterization of Fires for Design,” Interflam 1999, Conference

Proceedings of the 8 International Interflam Conference, Interscience Communication Limited, th

England, pp. 555–566, June-July 1999.

Gross, D., “Data Sources for Parameter Used in Predictive Modeling of Fire Growth and Smoke

Spread,” NBSIR 85-3223, U.S. Department of Commerce, National Bureau of Standards (NBS),

Gaithersburg, Maryland, 1985.

Heskestad, G. “Venting Practice,” Section 7, Chapter 7, NFPA Fire Protection Handbook, 18th

Edition, A.E. Cote, Editor-in-Chief, National Fire Protection Association, Quincy, Massachusetts,

pp. 7–105, 1997.

Madrzykowski, D., “Office Station Heat Release Study: Full Scale vs. Bench Scale,” Interflam 1996,

Conference Proceedings of the 7 International Interflam Conference, Interscience Communication th

Limited, England, Compiled by C.A. Franks, pp. 47–55, 1996.

Nelson, H.E., “An Engineering Analysis of the Early Stages of Fire Development: The Fire at the

Dupont Plaza Hotel and Casino on December 31, 1986,” NBSIR 87-3560, U.S. Department of

Commerce, National Bureau of Standards (NBS), Gaithersburg, Maryland, May 1987.

NFPA 72, “National Fire Alarm Code,” 1999 Edition, National Fire Protection Association, Quincy,

Massachusetts.

NFPA 92B, “Guide for Smoke Management Systems in Malls, Atria, and Large Areas,” 2000

Edition, National Fire Protection Association, Quincy, Massachusetts.
B-11

B.2 Elements of Hydraulic and Electrical Systems

Table B.2-1 provides the basic elements of a hydraulic system along with the corresponding

elements of an electrical system.

Table B.2-1. Corresponding Elements of Hydraulic and Electrical Systems

(NFPA 921, 2002 Edition)

Elements of a Hydraulic System Elements of an Electrical System

Pump Generator

Pressure Voltage (potential or electromotive force)

Pounds per square inch (psi) Volts (V)

Pressure gauge Voltmeter

Water Electrons

Flow Current

Gallons per minute (gpm) Amperes (A)

Flowmeter Ammeter

Valve Switch

Friction Resistance (Ohms)

Friction loss Voltage drop

Pipe size (inside diameter) Conductor size (AWG No.)

Hydraulic systems use a pump to create the hydraulic pressure necessary to force water through

pipes. The amount of hydraulic pressure is expressed in pounds per square inch (psi) and can be

measured with a pressure gauge. By contrast, electrical systems use a generator to create the

necessary electrical pressure (voltage) to force electrons through a conductor. The amount of

electrical pressure is expressed in volts and can be measured with a voltmeter.

In hydraulic systems, water flows in a useful way. The amount of water flow is expressed in gallons

per minute (gpm) and may be measured with a flowmeter. By contrast, electrical systems, it is

electrons that flow in a useful way in the form of electrical current. The amount of electrical current

is expressed in amperes (A) and may be measured with an ammeter. Electric current can be either

direct current (dc), such as supplied by a battery, or alternating current (ac), such as supplied by

an electrical utility company.

In hydraulic systems, water pipes provide the pathway for the water to flow. By contrast, electrical

systems, conductors such as wires provide the pathway for the current to flow.
B-12

In a closed circulating hydraulic system (as opposed to a fire hose delivery system, where water

is discharged out of the end of the hose), water flows in a loop, returning to the pump, where it

again circulates through the loop. When the valve is closed, the flow stops everywhere in the

system. When the valve is opened, the flow resumes. By contrast, an electrical system must be

a closed system, in that the current must flow in a loop known as a complete circuit. When the

switch is turned on, the circuit is completed and the current flows. When the switch is turned off,

the circuit is open (incomplete) and the current flow stops everywhere in the circuit. This voltage

drop is called the potential or electromotive force.

Friction losses in the pipes of a hydraulic system result in pressure drops. By contrast, electrical

friction (i.e., resistance) in conductors and other parts of an electrical system results in electrical

pressure drops or voltage drops. Ohm’s law must be used to express resistance as a voltage drop.

When electricity flows through a conducting material, such as a conductor, a pipe, or any piece of

metal, heat is generated. The amount of heat depends on the resistance of the material through

which the current is flowing and the amount of current. Some electrical equipment, such as heating

units, are designed with appropriate resistance to convert electricity to heat.

The flow of water in a pipe at a given pressure drop is controlled by the pipe size. A larger pipe

allows a greater volume (more gallons per minute) of water to flow than a smaller pipe at a given

pressure drop. Similarly, larger conductors allow more current to flow than smaller conductors.

Conductor sizes are given in American Wire Gauge (AWG) numbers. The larger the number, the

smaller the conductor diameter. The larger the diameter (and hence the larger the cross-sectional

area) of the conductor, the lower the AWG number and the less resistance the conductor has.

B.2.1 Reference

NFPA 921, “Guide for Fire and Explosion Investigations,” 2001 Edition, National Fire Protection

Association, Quincy, Massachusetts.
B-13

B.3 Classes of Fires

Generally the purpose of a letter designation given to a particular fire category is to classify it

according to the type of fuel and possible spread of the fire. The letter classification also provides

a general indication of the severity and type of the hazard. NFPA 10, “Standard for Portable Fire

Extinguishers,” classifies fires as either Class A, Class B, Class C, Class D, or Class K according

to the fuel involved.

Class A Fires

Fires in ordinary combustible materials, such as wood, cloth, paper, rubber, and many plastics.

Class B Fires

Fires in flammable or combustible liquids, petroleum greases, tars, oils, oil-based paints, solvents,

lacquers, alcohols, and flammable gases.

Class C Fires

Fires that involve energized electrical equipment where the electrical nonconductivity of the

extinguishing media is of importance. (When electrical equipment is de-energized, fire

extinguishers designed for Class A or Class B fires can be safely used).

Class D Fires

Fires in combustible metals, such as magnesium, titanium, zirconium, sodium, lithium, and

potassium.

Class K Fires

Fires in cooking appliances that involve combustible cooking media (vegetable or animal oils and

fats).

B.3.1 Reference

NFPA 10, “Standard for Portable Fire Extinguishers,” 2002 Edition, National Fire Protection

Association, Quincy, Massachusetts.
B-14

B.4 Classification of Hazards

B.4.1 Light (Low) Hazard

Light hazard occupancies are locations where the total amount of Class A combustible materials

(including furnishings, decorations, and content), is a minor quantity. This can include some

buildings or rooms occupied as offices, classrooms, churches, assembly halls, guest room areas

of hotels/motels, and so forth. This classification anticipates that the majority of content items are

either noncombustible or so arranged that a fire is not likely to spread rapidly. Small amounts of

Class B flammables used for duplicating machines, art departments, and so forth, are included,

provided that they are kept in closed containers and safely stored (Conroy, 1997 and NFPA 10).

B.4.2 Ordinary (Moderate) Hazard

Ordinary hazard occupancies are locations where of Class A combustibles and Class B flammables

are present in greater total amounts than expected under light (low) hazard occupancies. These

occupancies could consist of dining areas, mercantile shops, and allied storage; light

manufacturing, research operations, auto showrooms, parking garages, workshop or support

service areas of light (low) hazard occupancies; and warehouses containing Class I or Class II

commodities as defined by NFPA 231, “Standard for General Storage,” (Conroy, 1997 and NFPA 10).

B.4.3 Extra (High) Hazard

Extra hazard occupancies are locations where the total amount of Class A combustibles and Class

B flammable (in storage, production, use, finished product, or combination thereof) is over and

above those expected in occupancies classed as ordinary (moderate) hazard. These occupancies

could consist of woodworking, vehicle repair, aircraft and boat servicing, cooking areas, individual

product display showrooms, product convention center displays, and storage and manufacturing

processes such as painting, dipping, and coating, including flammable liquid handling. Also included

is warehousing or in-process storage of other than Class I or Class II commodities (Conroy, 1997

and NFPA 10).

B.4.4 References

Conroy, M.T. “Fire Extinguisher Use and Maintenance,” Section 6, Chapter 23, NFPA Fire

Protection Handbook, 18 Edition, A.E. Cote, Editor-in-Chief, National Fire Protection Association, th

Quincy, Massachusetts. 1997.

NFPA 10, “Standard for Portable Fire Extinguishers,” 2002 Edition, National Fire Protection

Association, Quincy, Massachusetts.

NFPA 231, “Standard for General Storage,” National Fire Protection Association, Quincy,

Massachusetts.
B-15

B.5 Classes of Fires and Extinguishing Agents

One or more of the following mechanisms—more often, several of them simultaneously—can be

used to extinguish fire:

• Physically separating the combustible substance from the flame

• Removing or diluting the oxygen supply

• Reducing the temperature of the combustible or of the flame

• Introducing chemicals that modify the combustion chemistry

For example, when water is applied to a fire of a solid combustible burning in air, several

extinguishing mechanisms are involved simultaneously. The solid is cooled by the contact with

water, causing its rate of pyrolysis, or gasification, to decrease. The gaseous flame is cooled,

causing a reduction in heat feedback to the combustible solid and a corresponding reduction in the

endothermic pyrolysis rate. Steam is generated, which, under some confined conditions, may

prevent oxygen from reaching the fire. Water in the form of fog may block radiative heat transfer.

As another example, consider the application of a blanket of aqueous foam to a burning pool of

flammable liquid. Several mechanisms may be operative. The foam prevents the fire’s radiant heat

from reaching the surface and supplying the needed heat of vaporization. If the fire point of the

flammable liquid is higher than the temperature of the foam, the liquid is cooled and its vapor

pressure decrease. If the flammable liquid is water soluble, such as alcohol, then, by a third

mechanism, it will become diluted by water from the foam, and the vapor pressure of the

combustible will be reduced.

As yet an example, when dry chemical is applied to a fire, the following extinguishing mechanisms

may be involved:

• Chemical interaction with the flame

• Coating of the combustible surface

• Cooling of the flame

• Blocking of radiative energy transfer
B-16

The agent mentioned above—water, foam, and dry chemicals—each work by a combination of

several mechanisms, and the relative importance of the various contributions varies with

circumstances. Table B.5-1 provides the classes of fires with examples and extinguishing agent.

Table B.5-1. Fire Classes with Extinguishing Agents

Fire

Class

Description Examples Extinguishing Agents

A Ordinary combustibles Wood, cloth, paper,

rubber, and many

plastics

Water, dry chemicals, foam,

some Halon

B Flammable liquids, gases, and

liquid-derived solids

Gasoline, oils, LPG,

paraffin or heavy

lubricants, grease

CO2, dry chemical agents,

Halon, foam (Class B

extinguishers isolate the fuel

from the heat by cutting off

oxygen to the combustion

zone or by inhibiting and

interrupting the formation of

molecular chain reactions)

C The same fuels as Class A and B

fires, together with energized

electrical equipment

Energized Class A

material, such as

household

appliances

CO2, dry chemical agents,

Halon (Extinguishers for Class

C fires are rated according to

the nonconductive properties

of the extinguishing agent)

D Combustible metals or metallic alloy

elements with combustible metal

components

Magnesium, sodium,

potassium, titanium,

zirconium, and

lithium

Dry chemical agents (Water

and water-based extinguishers

should never be used on Class

D fires. To be effective on a

Class D fire, an extinguisher

must suppress the fire without

reacting physically or

chemically with the

combustible metal materials)

K Cooking appliances that involve

combustible cooking media

Vegetable or animal

oils and fats

D 2ry chemical agents, CO , wet

chemical agents
B-17

B.6 Classification of Flammable and Combustible Liquids

In common usage, flammable refers to a liquid that is readily ignited, burns rapidly and vigorously,

and produces a lot of thermal energy—in other words, heat. Combustible usually refers to a liquid

that is less easily ignited, burns less rapidly, and is, therefore, relatively safer. In simple terms,

flammable liquids produce vapors at normal room temperature in concentrations that can be easily

ignited by a small spark or flame. Combustible liquids do not produce vapors that can be ignited

at normal room temperature. However, if a combustible liquid is heated up to or above its flash

point, the vapors generated by the now-heated liquid can be ignited. In these cases, combustible

liquids can be just as dangerous as flammable liquids. And, some of them, hydrocarbon fuels for

examples, can burn just rapidly and evolve just much heat once they are ignited. Some common

combustible liquids—mineral spirits and paint thinners, for example—are blended so they are just

above the accepted dividing line between flammable and combustible. So, moderate heating of

these liquids or storing them in a very warm environment can also present a fire hazard.

B.6.1 Flammable Liquid

According to most fire safety codes (NFPA 30, “Flammable Combustible Liquids Code”), a

flammable liquid is generally defined as any liquid that has a closed-cup flash point below 37.8 °C

(100 °F). Flash points may be determined by procedures and apparatus set forth in ASTM D56,

D92, D93, D1310, or D3278.

NFPA 11 defined flammable liquids as any liquid having flash point below 37.8 °C (100 °F) and

having a vapor pressure not exceeding 276 kPa (40 psi) (absolute) at 37.8 °C (100 °F).

Flammable liquids can be divided into classes (which are further divided into sub-classes), based

on their flash points as summarizes in Table B.6-1. Class I - Liquids have a flash point below 38 °C

(100 °F) and subdivided as follows:

Table B.6-1. Flammable Liquid Classifications

(NFPA 30, 2000 Edition)

Classification Flash Point (°F) Boiling Point (°F) Example(s)

Class IA

Flammable

< 73 < 100 Ethyl ether

Acetic aldehyde,

Dimethyl sulfide, Furan

Class IB

Flammable

< 73 $ 100 Ethyl alcohol, gasoline92 octane,

Cyclohexane

Class IC

Flammable

$73 and < 100 N/A Butyl ether
B-18

B.6.2 Combustible Liquid

A combustible liquid is defined as any liquid that has a closed-cup flash point above 37.8 °C

(100 °F). Combustible liquids can be divided into classes (which are further divided into subclasses), based on their flash points as summarizes in Table B.6-2.

Class II Combustible liquids with flash points at or above 38 °C (100 °F), but below 60 °C

(140 °F).

Class III Combustible liquids with flash points at or above 60 °C (140 °F).

Table B.6-2. Combustible Liquid Classifications

(NFPA 30, 2000 Edition)

Classification Flash Point (°F) Boiling Point (°F) Examples

Class II

Combustible

$ 100 N/A Fuel oil # 1 (kerosene),

diesel fuel oil # 1-D/2-D/4-D,

glacial acetic acid, and

jet fuel (A & A-1)

Class III A

Combustible

$ 140 and < 200 N/A Fuel oil # 6, creosote oil, and

butyl carbitol

Class III B

Combustible

$ 200 N/A Fuel oil # 4, mineral oil, olive oil,

and lubricating oil

(motor oil)

Assume that a liquid spill occurs on a summer day when the ground has been heated by the sun

to 35 °C (95 °F). Clearly, a spill of Class I (flammable) liquid is extremely hazardous with regard

to fire; however, a spill of a Class II liquid is dangerous from a fire viewpoint only if a heat source

exists that is capable of moderately raising the temperature of the liquid and a spill of Class III liquid

is safe from ignition unless a heat source exists that can substantially raise its temperature.
B-19

Table B.6-3 lists the flash points of some common flammable and combustible liquids. Notice the

wide range, from -43 °C to +243 °C (-45 °F to +469 °F). These values are meaningful only for bulk

liquids. If a liquid with a high flash point is in the form of a spray, a froth, or a foam, with air present,

and comes into contact with even a very small ignition flame, the tiny amount of liquid in contact will

be immediately heated to above its flash point and will begin to burn. The combustion energy

released will vaporize the surrounding spray or foam, and the fire will propagate (spread).

Table B.6-3. Flash Points of Flammable and Combustible Liquids

(Benedetti, 1997)

Liquid Fuel Flash Point

°C (°F)

Class I (Flammable) Liquids

Gasoline

n-Hexane

JP-4 (jet aviation fuel)

Acetone

Toluene

Methanol

Ethanol

Turpentine

-43 (-45)

-26 (-15)

-18 (0)

-16 (3)

9 (48)

11 (52)

12 (54)

35 (95)

Class II (Combustible) Liquids

No.2 fuel oil (domestic)

Diesel fuel

Jet A (jet aviation fuel)

Kerosene

No. 5 fuel oil

>38 (>100)

40–50 (104–131)

47 (117)

52 (126)

>54 (>130)

Class III (Combustible) Liquids

JP-5 (jet aviation fuel)

SAE No. 10 lube oil

Triresyl phosphate

66 (151)

171 (340)

243 (469)
B-20

B.6.3 Storage of Flammable and Combustible Liquids

Flammable and combustible liquids are packed, shipped, and stored in bottle, drums, and other

containers ranging in size up to 60 gal (225 L). Additionally, liquids are shipped and stored in

intermediate bulk containers up to 793 gal (3,000 L) and in portable intermodal tanks up to 5,500

gal (20,818 L). Storage requirements for each these containers are covered in the NFPA 30

chapters entitled, “Containers and Portable Tank Storage,” with the exception of those portable

tanks larger than 793 gal (3,000 L) that are required to meet the applicable requirements covered

in the NFPA 30 chapter entitled, “Tank Storage.”

Examples of containers types used for the storage of liquids include glass, metal, polyethylene

(plastic), and fiberboard. The maximum allowable size for the different types of containers is

governed by the class of flammable or combustible liquid to be stored in it. Table B.6-4 lists the

maximum allowable size (capacity) of a container or metal tank used to store flammable and

combustible liquids.

Table B.6-4. Maximum Allowable Size of Containers and Portable Tanks 

for Flammable and Combustible Liquids (NFPA 30, 2000 Edition)

Liquid Container Type Flammable

Liquid

Combustible

Liquid

Class

IA 

Class

IB

Class

IC

Class

II

Class

III

Glass 1 pt 1 qt 1 gal 1 gal 5 gal

Metal (other than DOT drum) or approved

plastic

1gal 5 gal 5 gal 5 gal 5 gal

Safety cans 2 gal 5 gal 5 gal 5 gal 5 gal

Metal drum (DOT specification) 60 gal 60 gal 60 gal 60 gal 60 gal

Approved metal portable tank and IBC 793 gal 793 gal 793 gal 793 gal 793 gal

Rigid plastic IBC (UN 31H1 or 31H2) or

composite IBC (UN 31HZ1)

NP NP NP 793 gal 793 gal

Polyethylene (DOT specification 34, UN 1H1,

or as authorized by DOT exemption)

1 gal 5 gal 5 gal 60 gal 60 gal

Fiber drum

(NMFC or UFC Type 2A; Types 3A, 3B-H, or

3B-L; or Type 4A)

NP NP NP 60 gal 60 gal

SI Units - 1pt = 0.473 L; 1 qt = 0.95 L; 1 gal = 3.8 L

NP = Not Permitted

IBC = Intermediate Bulk Container

DOT = U.S. Department of Transportation
B-21

B.6.4 Flammable Combustible Storage Cabinets

Most commercially available and approved storage cabinets are built to hold 60 gallons (227 liters)

or less of flammable and/or combustible liquids.

Not more than 120 gal (454 L) of Class I, Class II, and Class IIIA liquids shall be stored in a

storage cabinet. Of this 120 gal total, not more than 60 gal (227 L) shall comprise Class and

Class II liquids.

B.6.5 Definitions

Flash Point

The minimum temperature to which a liquid must be heated in a standardized apparatus, so that

a transient flame moves over the liquid when a small pilot flame is applied.

Alternately, the flash point of a liquid may be defined as the temperature at which the vapor and air

mixture lying just above its vaporizing surface is capable of just supporting a momentary flashing

propagation of a flame prompted by a quick sweep of small gas pilot flame near its surface (hence

the term flash point). The flash point is mainly applied to liquids. The flash point of liquid is one of

its characteristics that normally determines the amount of fire safety features required for its

handling, storage, and transport.

Fire Point

The minimum temperature to which a liquid must be heated in a standardized apparatus, so that

sustained combustion results when a small pilot flame is applied, as long as the liquid is at normal

atmospheric pressure.

Boiling Point

The temperature at which the transition from the liquid to the gaseous phase occurs in a pure

substance at fixed pressure. Alternatively, the boiling point may be defined as the temperature at

which the vapor pressure of a liquid equals the surrounding atmospheric pressure. For purposes

of defining the boiling point, atmospheric pressure shall be considered to be 14.7 psia (760 mm

Hg). For mixtures that do not have a constant boiling point, the 20-percent evaporated point of a

distillation performed in accordance with ASTM D86, “Standard Method of Test for Distillation of

Petroleum Products,” shall be considered to be the boiling point.

Autoignition

Initiation of fire or combustion by heat but without the application of a spark or flame.

Autoignition Temperature

The lowest temperature at which a mixture of fuel and oxidizer can propagate a flame without the

aid of an initiating energy source (pilot, spark, or flame).

High-Risk Fuel

Class IA, IB, IC, or II liquids as defined by NFPA 30, “Flammable and Combustible Liquids Code,”

or Class IIIA, or III B liquids heated to within 10 °C (50 °F) of their flash point, or pressurized to

174.4 kPa (25.3 psi) or more.
B-22

B.6.6 Hazardous Materials

A substance (solid, liquid, or gas) capable of creating harm to people, property, and the

environment. The general category of hazard assigned to a hazardous material under the U.S.

Department of Transportation (DOT) regulation. Table B.6-5 lists the hazardous material

classification.

Table B.6-5. Hazardous Material Classification

Hazard Class Description

Class 1 - Explosives

Division 1.1

Division 1.2

Division 1.3

Division 1.4

Division 1.5

Division 1.6

Explosive with a mass explosion hazard

Explosives with a projection hazard

Explosives with predominantly a fire hazard

Explosives with no significant blast hazard

Very insensitive explosives

Extremely insensitive explosive articles

Class 2

Division 2.1

Division 2.2

Division 2.3

Division 2.4

Flammable gas

Nonflammable, non-poisonous compressed gas

Poison gas

Corrosive gas 

Class 3 - Flammable Liquid

Division 3.1

Division 3.2

Division 3.3

Flammable liquids, flash point < 0 °F

Flammable liquids, flash point 0 °F and above but < 73 °F

Flammable liquids, flash point 73 °F and up to < 141 °F

combustible liquid

Class 4

Division 4.1

Division 4.2

Division 4.3

Flammable solid

Spontaneously combustible material

Dangerous when wet material

Class 5

Division 5.1

Division 5.2

Oxidizer

Organic peroxide

Class 6

Division 6.1

Division 6.2

Poisonous material

Infectious material

Class 7 Radioactive material

Class 8 Corrosive material

Class 9 Miscellaneous hazardous material, ORM-D material
B-23

B.6.7 References

Benedetti, R.P., Editor, “Flammable and Combustible Liquids Code Handbook,” 6 Edition, National th

Fire Protection Association, Quincy, Massachusetts, 1997.

NFPA 11, “Standard for Low-Expansion Foam,” 2002 Edition, National Fire Protection Association,

Quincy, Massachusetts.

NFPA 30, “Flammable and Combustible Liquids Code,” 2000 Edition, National Fire Protection

Association, Quincy, Massachusetts.
B-24

B.7 Classification of Flammable Gases

B.7.1 Classification

Flammable gases are classified according to the maximum experimental safe gap (MESG), which

prevents flame passage. MESG is determined by test IEC 79-1A, “Electrical Apparatus for

Explosive Gas Atmospheres,” International Electrotechnical Commission (IEC), 1975

(Senecal, 1997).

Class I Group A - acetylene

Group B - hydrogen

Group C - ethylene

Group D - propane

Division 1 Flammable gases or combustible dust may be present at ignitable concentrations,

under normal operating conditions.

Division 2 Where hazardous materials may be handled, processed, or used; ignitable

atmospheres not normally present due to containment or ventilation of hazardous

materials; areas adjacent to Division 1 locations.

B.7.2 Definitions

Flammable Limits

The minimum and maximum concentration of combustible material in a homogeneous mixture with

a gaseous oxidizer that will propagate a flame.

Upper and Lower Flammability Limits

Concentration of fuel in air in which a premixed flame can propagate.

Lower Flammability Limit

The lowest concentration of fuel in air at normal temperature and pressure that can support flame

propagation is known as the lower flammability limit (LFL) or lower explosive limit (LEL).

Upper Flammability Limit

The highest concentration of fuel in air at normal temperature and pressure that can support flame

propagation is known as the upper flammability limit (UFL) or upper explosive limit (UEL).

B.7.3 Reference

Senecal, J.A., “Explosion Prevention and Protection,” Section 4, Chapter 14, NFPA Fire Protection

Handbook, 18 Edition, A.E. Cote, Editor-in-Chief, National Fire Protection Association, Quincy, th

Massachusetts, 1997.
B-25

B.8 Flammability Hazards of Gases

B.8.1 Flammability Potential of Gases

Flammability hazards in a tank or vessel dependent upon the potential for developing a flammable

fuel/oxidant/inert gas mixture in the tank or vessel head space. Mixtures of fuel and air are only

flammable for limited fuel-to-air ratio. The most flammable mixture is a stoichiometric mixture, in

which the fuel and air (oxygen) are present in exactly the right proportions for oxidation, as dictated

by the stoichiometry of the fuel/oxygen combustion reaction. Mixtures with some excess oxygen

or excess fuel are also flammable, the lowest concentration of fuel in air that can support flame

propagation at normal temperature and pressure is known as the lower explosive limit (LEL).

Similarly, the highest concentration of fuel in air that can support flame propagation at normal

temperature and pressure is known as the upper explosive limit (UEL). Mixtures of fuel in air with

intermediate fuel concentrations will support flame propagation.

The flammability of gas mixtures is determined by one of two widely utilized laboratory methods.

The first method uses a 5-foot-long tube that is filled with the test mixture, and a spark is used to

ignite the mixture at one end to observe whether ignition occurs and whether the flame can

propagate to the other end of the tube. The second method uses a spherical tank or vessel that

is filled with the test mixture, and a spark is used to ignite the mixture at the center of the tank or

vessel to measure the pressure increase to determine whether flame propagation occurred

throughout the tank or vessel (Beyler, 1995). The spherical vessel test method is more

representative of an actual tank or vessel than is the tube method.

The terms “explosive limits” and “flammable limits” are used interchangeably in the technical

literature. Explosive limits simply refer to compositions, which define when flame propagation is

possible. The flame propagation is known as a deflagration and results in a pressure increase as

the flame passes through a vessel. This resulting overpressure is the origin of the term explosive

limit, where an explosion is any event, that results in a sudden overpressure in the vessel.

When the LEL mixture has excess oxygen and insufficient fuel for complete burning, the mixture

is known as “fuel lean.” The potential heat output, which defines how hot the products of

combustion can be is limited not by oxygen, but by fuel concentration. The ideal “no heat loss”

post-combustion temperature is known as the “adiabatic flame temperature” (AFT). For most

flammable gases, the AFT at atmospheric pressure is about 2,300 K (3,680 °F) for stoichiometric

mixtures of fuel in air, and is reduced to about 1,600 K (2,420 °F) for LEL mixtures. The AFT can

be calculated using any of a number of chemical equilibrium computer programs, like STANJAN

(Reynolds, 1986). The use of such a computer program allows the analysis to be performed for a

tank-specific mixture, so that the results are representative of the actual tank environment.
B-26

B.8.2 Flammability Potential of Hydrogen

Hydrogen is a highly flammable gas with novel flammability properties and unusually broad

explosive limits. Based on upward propagation in the standard flammability tube, the LEL is

4-percent hydrogen in air and the UEL is 75-percent (Zabetaskis, 1965). For most gases, the LELs

for upward and downward propagation do no differ greatly. However, for hydrogen, the LEL for

downward propagation is 8-percent (Furno et al., 1971). The significance of this difference is that

in order for the flame to propagate throughout a tank or a vessel, it must propagate in all directions.

As such, overpressures associated with hydrogen explosions are not observed at hydrogen

concentrations below 8-percent. This behavior was observed by Furno et al., 1971, in 12-foot

spherical vessel experiments using lean hydrogen/air mixtures. Overpressures were only

measured above 8-percent hydrogen, and the pressures did not match the theoretical

overpressures until about 10-percent hydrogen. Thus, while the LEL of hydrogen is widely quoted

as 4-percent, explosion hazards will not occur below 8-percent.

The novel behavior of hydrogen is not reflected in documents like NFPA 69, “Standard on Explosion

Prevention Systems.” As such, standards of care like NFPA 69, provide an implicit additional safety

factor for hydrogen that should be understood in assessing hazards.

B.8.3 Flammable Limits, Detonable Limits, and Potential for Deflagration-to-Detonation

Transitions

The formation of flammable fuel/oxidant mixtures within a tank can lead to premixed flame

propagation in the form of deflagration or a detonation. The formation of a flammable mixture can

result from steady-state generation and transport of flammable gases and oxidizers from an

aqueous solution or waste containing radioactive isotopes, from episodic releases of such gases

trapped within the waste, or from the formation of large gas bubbles within the waste which contain

flammable mixtures of fuels and oxidizers.

Before assessing the potential flammable gas generation rates and resulting flammable gas

mixture, it is useful to assess the relevant limits. In mixtures with fuel gas concentrations above the

LEL indefinite propagation of a deflagration is possible. Above the detonable limit, indefinite

propagation of a detonation is possible given a source that is capable of directly detonating the

mixture. While LELs are a property of the mixture alone, the detonable limits are also impacted by

the environment. The ability for a deflagration-to-detonation transition (DDT) is contingent upon

both the mixture and the environment. The primary flammable gas is hydrogen.

B.8.4 Flammable Gas Generation

Flammable gases are generated with the aqueous solution or waste by several processes within

a tank or a vessel. Specifically, these processes may include (1) radiolysis of the water and waste

to produce hydrogen and ammonia, (2) corrosion of the steel liner to produce hydrogen, and

(3) chemical decomposition of the waste. These processes generate hydrogen, methane, ammonia,

and nitrous oxide, the first three of which are flammable gases, while the fourth is an oxidizer.
B-27

B.8.5 Explosion Prevention Methods

The flammability of a tank or vessel can be managed by controlling either the flammable gas

concentration or oxygen concentration. Where the oxygen concentration is to be controlled, it

needs to be maintained below the limiting oxidant concentration (LOC) (NFPA 69). (LOC is defined

as the concentration of oxidant below which deflagration cannot occur is a specified mixture).

Safety margins require maintaining the oxygen at 60-percent of the LOC if the LOC is above 5-

percent, or 4-percent of the LOC if the LOC is below 5-percent. Where flammability is measured

by controlling the flammable gas concentration, it needs to be maintained below 25 percent of the LEL.

Control of the oxygen concentration is achieved through the use of an inert purge gas. By contrast,

control of flammable gas concentration is normally achieved through air dilution or by controlling

of flammable gas evolution or regeneration or by catalytic oxidation of flammable gases.

While NFPA 69, provides standards for inerting the tanks, such inerting is not required by codes

and standards for flammable liquid storage containers, such as the Uniform Fire Code Article 79;

1997, NFPA 30, 1996 Edition; 49 CFR; FM Data Sheet 7-88, “Storage Tanks for Flammable and

Combustible Liquids,” 1999; and FM Data Sheet 7-29, “Flammable Liquid Storage,” 1999. These

codes and standards recognize that ignition sources will not be present in passive containers, so

that it is not necessary to control the composition of gases in the tank. By contrast, FM Data Sheet

7-32, “Flammable Liquids Operation,” 1993, recommends that processing equipment with the

potential for an explosion should have at least one of the following characteristics:

• equipped with explosion venting

• designed to withstand the explosion overpressure

• fitted with an inerting system

• fitted with an explosion suppression system

Tank inerting is recognized as a means of preventing explosions in processing vessels, which are

inherently dynamic systems where ignition sources can be limited but not excluded.
B-28

B.8.6 References

Beyler, C.L., “Flammability Limits of Premixed and Diffusion Flames,” Section 2, Chapter 2-9, SFPE

Handbook of Fire Protection Engineering, 2 Edition, P.J. DiNenno, Editor-in-Chief, National Fire nd

Protection Association, Quincy, Massachusetts, 1995.

FM Data Sheet 7-29, “Flammable Liquid Storage,” Factory Mutual Engineering Corporation,

Norwood, Massachusetts.

FM Data Sheet 7-32, “Flammable Liquid Operations,” Factory Mutual Engineering Corporation,

Norwood, Massachusetts.

FM Data Sheet 7-88, “Storage Tanks for Flammable and Combustible Liquids,” Factory Mutual

Engineering Corporation, Norwood, Massachusetts.

Furno, A., E. Cook, J. Kuchta, and D. Burgess, “Some Observations on Near-Limit Flames,”

Thirteenth Symposium (International) on Combustion, The Combustion Institute, Pittsburgh,

Pennsylvania, pp. 593–599, 1971.

NFPA 30, “Flammable and Combustible Liquids Code,” 2000 Edition National Fire Protection

Association, Quincy, Massachusetts.

NFPA 69, “Standard on Explosion Prevention Systems,” 1997 Edition, National Fire Protection

Association, Quincy, Massachusetts.

Reynolds, W.C., “The Element Potential Method for Chemical Equilibrium Analysis: Implementation

in the Interactive Program STANJAN, Version 3, Department of Mechanical Engineering, Stanford

University, 1986.

Uniform Fire Code (UFC), Article 79, “Flammable and Combustible Liquids,” International Fire Code

Institute, 1997.

Code of Federal Regulations, Title 49, Part 100–177, “Hazardous Materials Transportation,”

U.S. Government Printing Office, Washington DC.

Zabetakis, M.G., “Flammability Characteristics of Combustible Gases and Vapors,” Bulletin 627,

U.S. Bureau of Mines, Washington, DC, 1965.
B-29

B.9 Combustion Properties of Pure Metals in Solid Form

Nearly all metals will burn in air under certain conditions. Some oxidize rapidly in the presence of

air or moisture, generating sufficient heat to reach their ignition temperatures. Others oxidize so

slowly that heat generated during oxidation dissipates before the metal becomes hot enough to

ignite. Certain metals (notably magnesium, titanium, sodium, potassium, lithium, zirconium,

hafnium, calcium, zinc, plutonium, uranium, and thorium) are referred to as “combustible metals”

because of the ease of ignition when they reach a high specific area ratio (thin sections, fine

particles, or molten states). However, the same metals are comparatively difficult to ignite in

massive solid form. Some metals (such as aluminum, iron, and steel) that are not normally thought

of as combustible, may ignite and burn when in finely divided form. Clean fine steel wool, for

example, may ignite. Particle size, shape, quantity, and alloy are important factors to be considered

when evaluating metal combustibility. Combustibility of metallic alloys may differ and vary widely

from the combustibility characteristics of the alloys’ constituent elements. Metals tend to be most

reactive when in finely divided form and may require shipment and storage under inert gas or liquid

to reduce fire risks.

Hot or burning metals may react violently upon contact with other materials, such as oxidizing

agents and extinguishing agents used on fires involving ordinary combustibles or flammable liquids.

Temperatures produced by burning metals can be higher than temperatures generated by burning

flammable liquids. Some metals can continue to burn in carbon dioxide, nitrogen, water, or steam

atmospheres in which ordinary combustibles or flammable liquids would be incapable of burning.

Properties of burning metal cover a wide range. Burning titanium, for example, produces little

smoke, while burning lithium exudes dense and profuse smoke. Some water-moistened metal

powders (such as zirconium) burn with near-explosive violence, while the same powder wet with

oil burns quiescently. Sodium melts and flows while burning; calcium does not. Some metals (such

as uranium) acquire an increased tendency to burn after prolonged exposure to moist air, while

prolonged exposure to dry air makes it more difficult to ignite.

The toxicity of certain metals is also an important factor in fire suppression. Some metals

(especially heavy metals) can be toxic or fatal if they enter the bloodstream or their smoke fumes

are inhaled. Metal fires should never be approached without proper protective equipment

(clothing and respirators).

A few metals (such as thorium, uranium, and plutonium) emit ionizing radiation that can complicate

fire fighting and introduce a radioactive contamination problem. Where possible, radioactive

materials should not be processed or stored with other pyrophoric materials because of the

likelihood of widespread radioactive contamination during a fire. Where such combinations are

essential to operations, appropriate engineering controls and emergency procedures should be in

place to prevent or quickly suppress fires in the event that the controls fail.

Because extinguishing fires in combustible metals involves techniques not commonly encountered

in conventional fire fighting operations, it is necessary for those responsible for controlling

combustible metal fires to be thoroughly trained before an actual fire emergency arises. Table B.9-1

lists the melting, boiling, and ignition temperatures of pure metals in solid form.
B-30

Table B.9-1. Melting, Boiling, and Ignition Temperatures of Pure Metals in Solid Form

(Tapscott, 1997, © NFPA. With permission.)

Pure Metal Melting Point Boiling Point Solid Metal Ignition

Temperature 

°C °F °C °F °C °F

Aluminum 660 1,220 2,452 4,445 555 1,832 b, c b, c

Barium 725 1,337 1,140 2,084 175 347 b b

Calcium 824 1,548 1,440 2,625 704 1,300

Hafnium 2,223 4,023 5,399 9,750 - -

Iron 1,535 2,795 3,000 5,432 930 1,706 b b

Lithium 186 367 1,336 2,437 180 356

Magnesium 650 1,202 1,110 2,030 623 1,153

Plutonium 640 1,184 3,315 6,000 600 1,112

Potassium 62 144 760 1,400 69b 156b

Sodium 98 208 880 1,616 115 239 d d

Strontium 774 1,845 1,150 2,102 720 1,328 b b

Thorium 1,845 3,353 4,500 8,132 500 932b b

Titanium 1,727 3,140 3,260 5,900 1,593 2,900

Uranium 1,132 2,070 3,815 6,900 3,815 6,900 b, e b, e

Zinc 419 786 907 1,665 900 1,652 b b

Zirconium 1,830 3,326 3,577 6,470 1,400 2,552 b b

Notes:

(a) Variation of test conditions may produce different results

(b) Ignition in oxygen

(c) Spontaneous ignition on moist air

(d) Above indicated temperature

(e) Below indicated temperature

B.9.1 Reference

Tapscott, R.E. “Metals,” Section 4, Chapter 16, NFPA Fire Protection Handbook, 18 Edition, th

A.E. Cote, Editor-in-Chief, National Fire Protection Association, Quincy, Massachusetts. 1997.
B-31

B.10 Extinguishing Agents for Metal Fires

Water is not usually recommended for fires involving metals since a number of metals can react

exothermically with water to form hydrogen, which, of course, burns rapidly. Furthermore, violent

steam explosions can result if water enters molten metal. As an exception, fires have been

successfully extinguished when large quantities of water were applied to small quantities of burning

magnesium in the absence of pools of molten magnesium.

Table B.10-1 lists extinguishing agents used for various metal fires. In general, metal fires are

difficult to extinguish because of the very high temperatures involved and the correspondingly long

cooling times required. Note that certain metals react exothermically with nitrogen or carbon

dioxide, so the only acceptable inert gases for these metals are helium and argon. Halons should

not be used on metal fires.

Table B.10-1. Extinguishing Agents for Metal Fires

(Tapscott, 1997, © NFPA. With permission.)

Extinguishing Agent Main Ingredient Used On

Powders

Metal Guard Graphite Al, Ca, Hf, K, Li, Mg, Na, Pu, Th, Ti, U, Zr ®

Met-L-X NaCl Al, K, Mg, Na, Ti, U, Zr ®

TEC 2 powder KCl, NaCl, BaCl K, Mg, Na, Pu, U ®

Lith-X Graphite Li, Mg, Na, Zr ®

Na-X Sodium carbonate Na ®

Copper powder Cu Al, Li, Mg

Salt NaCl K, Mg, Na

Soda ash Sodium carbonate K, Na

Gases

Argon Ar Any metal

Helium He Any metal

Ni 2trogen N K, Na

Bo 3ron trifluoride BF Mg

Al-Aluminum, Ca-Calcium, Hf-Hafnium, K-Potassium, Li-Lithium, Mg-Magnesium,

Na-Sodium, Pu-Plutonium, Th-Thorium, Ti-Titanium, U-Uranium, Zr-Zirconium
Model Building Codes; National Fire Protection Association, NFPA 5000; International Code 1

Council, Inc., International Building Code (IBC).

B-32

B.10.1 References

Friedman, R., Principles of Fire Protection Chemistry and Physics, “Fire-Fighting Procedures,”

Chapter 14, 3 Edition, National Fire Protection Association, Quincy, Massachusetts, 1998. rd

Tapscott, R.E., “Combustible Metal Extinguishing Agents and Application Techniques,” Section 6,

Chapter 26, NFPA Fire Protection Handbook, 18 Edition, A.E. Cote, Editor-in-Chief, National Fire th

Protection Association, Quincy, Massachusetts, 1997.

B.11 Occupancy Classification and Use Groups

National Fire Code (NFC) requirements are occasionally tied to specific type of occupancy. While

NPPs are fundamentally industrial occupancy, it is important to have a basic understanding of other

occupancy classifications in order to be able to recognize this connection.

The use group classification of a building is probably the most significant design factor that affects

the safety of the occupants and fire suppression forces that are called upon in the event of fire. The

building’s height and size, type of construction, type and capacity of exit facilities, and fixed fire

suppression systems are all dependent on this classification. The use group classification system

as the foundation for the building and fire prevention codes.

B.11.1 Occupancy Classification

The model building codes and NFPA 101 (Life Safety Code ) separate buildings into about 1 ®

10 general uses:

• Assembly

• Business

• Educational

• Factory or Industrial

• High Hazard or Hazardous

• Institutional

• Mercantile

• Residential

• Storage

• Utility, Miscellaneous, or Special
B-33

The uses are further separated into use groups based on specific characteristics. A church, a

nightclub, and a family restaurant are all assemblies, but the specific characteristics of their

occupants and functions differ drastically, requiring different built-in levels of protection. The

occupants of a church are probably very familiar with the building that they occupy. They have

been there before and they know the locations of alternative exits. The occupants of a nightclub

may not be so familiar with the building. Dim lighting, loud music, and impairment by alcohol are

all common features that may further compromise the ability of the occupants to identify a fire

emergency and take appropriate measures to escape:

• Assembly (A) occupancies are subdivided by function, as well as the number of occupants

they hold. Assemblies that hold fewer than 50 persons are generally considered to be lessrestrictive business uses. The International Building Code (IBC) further subdivides

assemblies that hold many people. Such assemblies include churches, restaurants with

occupant loads that exceed 50 persons, auditoriums, armories, bowling alleys, courtrooms,

dance halls, museums, theaters, and college classrooms that hold more than 50 persons.

• Business (B) areas include college classrooms with occupant loads up to 50, doctor’s and

other professional offices, fire stations, banks, barber shops, and post offices. Dry cleaners

who use noncombustible solvents (Types IV and V) also qualify as Business uses.

• Educational (E) areas include facilities that are not used for business or vocational training

(shop areas) for students up to and including the twelfth grade. Colleges and universities

are Business or Assembly areas (depending on the number of occupants). Day care

facilities may be classified as Educational or Institutional depending on the model code.

• Factory or Industrial (F) areas include industrial and manufacturing facilities and are

subdivided into moderate and low-hazard facilities. High-hazard factory and industrial areas

are bumped up from the F Use Group to the H Use Group. Dry cleaners employing

combustible solvents (types II and III) are moderate-hazard factory and industrial uses.

• High Hazard or Hazardous (H) areas are those in which more than the exempt amount of

a hazardous material or substance is used or stored. Exempt amounts of hazardous

materials are not exempt from the provisions of the code. They are threshold amounts by

material, above which the occupancy must comply with the stringent requirements of the

H Use Group.

• Institutional (I) areas may include halfway houses and group homes, hospitals and nursing

homes, and penal institutions. The model codes differ in their breakdown. Care must be

taken when considering homes for adults and day care centers as to whether the occupants

are ambulatory or capable of self-preservation. The model codes all contain significantly

more stringent requirements for institutional occupancies where a “defend-in-place” strategy

is necessary because of the inability of the occupants to flee the structure without

assistance.

• Mercantile (M) uses include retail shops and stores and areas that display and sell stocks

of retail goods. Automotive service stations that do minor repairs are considered Mercantile

uses. 

• Residential (R) areas include hotels and motels, dormitories, boarding houses, apartments,

townhouses, and one- and two-family dwellings.
B-34

• Storage (S) areas are used for to store goods and include warehouses, storehouses, and

freight depots. Storage uses are separated into low- and moderate-hazard storage uses.

Auto repair facilities that perform major repairs, including engine overhauls and body work

or painting, are considered Moderate-Hazard Storage Occupancies by the International

Building Code (IBC). Occupancies that store more than the exempt amounts of hazardous

materials or substances are considered H Use Group Occupancies.

• Utility (U), Miscellaneous, or Special Structures, depending on the model code, include

those that are not classified under any other specific use. Such structures may include tall

fences cooling towers, retaining walls, and tanks.

• Mixed-use buildings often contain multiple occupancies with different uses. For example,

a three-story building might have a restaurant (assembly) and computer store (mercantile)

on the first floor and professional offices throughout the rest of the building. The model

code provides for such situations either by requiring that the whole building be constructed

to all requirements of the most restrictive use group or by separating the areas with firerated assemblies, or by separating the building with fire walls, thereby creates separate

buildings. By far the least expensive and most attractive method of separating mixed uses

is by using fire separating assemblies, but this method is sometimes impossible because

of building height and area requirements.

B.11.2 Special Use and Occupancy Requirements

For most buildings and structures, assigning a use group and then specifying building requirements

for all buildings within that use group works relatively well. Most mercantile occupancies share

common hazards. Most business occupancies have similar occupants and processes. But what

if a given business happens to be on the twenty-sixth floor of a high-rise building? Or what if the

men’s clothing store is in the middle of a giant shopping mall? The relative hazards suddenly

change, and we begin comparing apples to oranges.

Building codes provide an enhanced level of protection for certain occupancies to compensate for

special hazards over and above those posed by the use of the building. The inherent hazards

posed by being located 26 stories above the ground or in a large open area with high fire loading

such as a shopping mall are addressed as special use requirements.

B.11.3 Code Advances/Changes

It is important to recognize that NPPs have their design basis rotted in 1970's era code

requirements. In some cases, fire science advances revise, or establish new code requirements.

A good example is carpeting found in the MCR. The original NPPs required ASTM E84, “Standard

Test for Surface Characteristics of Building Materials,” Class A flame spread requirements. Fire

science advances have developed more specialized test methods for carpeting, ASTM E648,

“Standard Test Method for Critical Radiant Flux of Floor-Covering Systems Using a Radiant Heat

Energy Source.” As a result of this, manufacturers do not test the material to 1970's vintage test

method. When NPPs perform a plant modification (e.g., replace the carpet in the MCR, since

ASTM E84 rated carpet is no longer manufactured), the licensee will either have to perform their

own ASTM E84 testing on the proper carpet or prepare an engineering analysis on the

commercially available carpeting that is tested to newer test methods recognized by NFPA 101,

“Life Safety Code .” ®
B-35

Another area of change is cable flame spread testing. Since no new NPPs are being built there is

little incentive for cable vendors to qualify electrical cables to IEEE 383 requirements. In parallel,

the building code groups are recognizing by grouped electrical cables and testing organizations

prepared specialized test methods and rating systems based on application of the cable: UL 910,

“Test Method for Fire and Smoke Characteristics of Electrical and Optical-Fiber Cables Used in Air

Handling Spaces”; UL 1581, “Reference Standard for Electrical Wires, Cables, and Flexible Cords”;

UL 1666, “Standard Test for Flame Propagation Height of Electrical and Optical-Fiber Cable

installed Vertically in Shafts”; and UL 1685, “Fire Test of Limited-Smoke Cables.”

B.11.4 References

ASTM Fire Test Standard, Fifth Edition, American Society of Testing and Materials, West

Conshohocken, Pennsylvania, pp. 765-780, 1999.

ASTM E 648-98 , “Standard Test Method for Critical Radiant Flux of Floor-Covering Systems Using ,1

a Radiant Heat Energy Source,” ASTM Fire Test Standard, Fifth Edition, American Society of

Testing and Materials, West Conshohocken, Pennsylvania, pp. 894-907, 1998.

International Building Code, Sixth Edition, International Code Council, Inc., Falls Church, Virginia.

NFPA 101 , “Life Safety Code ,” 2003 Edition, National Fire Protection Association, Quincy, ® ®

Massachusetts.

NFPA 5000, “Building Construction and Safety Code,” 2003 Edition, National Fire Protection

Association, Quincy, Massachusetts.

UL 910, “Test Method for Fire and Smoke Characteristics of Electrical and Optical-Fiber Cables

used in Air Handling Spaces.”

UL 1581, “Reference Standard for Electrical Wires, Cables, and Flexible Cords.”

UL 1666, “Standard Test for Flame Propagation Height of Electrical and Optical-Fiber Cable

Installed Vertically in Shafts.”

UL 1685, “Fire Test of Limited-Smoke Cables.”
B-36

B.12 Building Limitations and Types of Construction

Two of the most effective methods used over the years to limit potential fire spread and prevent

conflagration have been limiting the size of buildings and regulating the materials used in their

construction. One of the primary purposes of a building code is to prescribe standards that will

keep buildings from falling down. Besides gravity, there are many forces that act against a building.

Snow loads, wind loads, and potential earthquake loads are provided for in the building code for

design and construction of buildings. It can be considered that the potential force that requires the

most extensive code provisions is fire. Large portions of the model building codes address fire

protection issues, fire safety, emergency egress, and structural stability.

The key to understanding building code provisions for structural protection from fire is the concept

of fire resistance. In broad terms, fire resistance (also called fire endurance) it is the ability of a

building to resist collapse or total involvement in fire. Fire resistance is measured by the length of

time typical structural members and assemblies resist specified temperatures. The building codes

define fire resistance as that property of materials or their assemblies which prevents or retards the

passage of excessive heat, hot gases, or flames under conditions of use.

B.12.1 Types of Construction

There are three key points to remember when dealing with building construction types:

• All construction is either combustible (it will burn) or noncombustible (it won’t).

• When applied to construction materials, “protected” refers to measures to reduce or

eliminate the effects of fire encasement. Concrete, gypsum, and spray-on coatings are all

used to protect construction elements. When the code means “protected with a sprinkler

system,” it will say just that.

• Having the ability to determine the construction type by eyeballing a building is not a

requirement.
B-37

B.12.2 Five Construction Types

The model building codes and NFPA 220, “Standard on Types of Building Construction,” recognize

five construction types. The Standard Building Code subdivides noncombustible construction and

uses six types. The terms vary a little between the different codes, but the concept is the same,

based on the classifications from NFPA 220.

Type I Fire Resistive

In Type I construction, the structural elements are noncombustible and protected. Type I

is divided into two or three subtypes, depending on the model code. The difference

between them is the level of protection for the structural elements (expressed in hours).

Only noncombustible materials are permitted, and structural steel must not be exposed. A

high-rise building with an encased steel structure is an example of a Type I building.

Type II Noncombustible

In Type II construction, the structural elements are either noncombustible or limited

combustible. Type II is subdivided into subtypes, dependent upon the level of protection

(in hours) for the structural elements. The buildings are noncombustible, but afford limited

or no fire resistance to the structural elements. A strip shopping center, with block walls,

steel bar joists, unprotected steel columns, and a steel roof deck is an example of a Type

II building.

Type III

Limited Combustible (Ordinary) In Type III construction, the exterior walls are

noncombustible (masonry) and may be rated based on the horizontal distance to exposure.

The interior structural elements may be combustible or a combination of combustible and

noncombustible. Type III is divided into two subtypes (protected and unprotected). The

brick, wood joisted buildings that line city streets are of Type III (ordinary) construction.

Buildings with a masonry veneer over combustible framing are not Type III.

Type IV

Heavy Timber In type IV construction, the exterior walls are noncombustible (masonry) and

the interior structural elements are unprotected wood of large cross-sectional dimensions.

Columns must be at least 8 inches if they support a floor load, joists, and beams must be

a minimum of 6 inches in width and 10 inches in depth. Type IV is not subdivided. The

inherent fire-resistant nature of large-diameter wood members is taken into account.

Concealed spaces are not permitted.

Type V

Wood Frame In Type V construction, the interior structure may be constructed of wood or

any other approved material. Brick veneer may be applied, but the structural elements are

wood frame. Type V is divided into two subtypes (protected and unprotected), again

depending on the protection provided for the various structural elements.
B-38

B.12.3 Fire Resistance Ratings

The various model codes and NFPA 220 each have a table containing the rating (in hours) of the

various structural elements. Table B.12-1 summarizes the required ratings by building component

type, depending upon the construction classification of the building. The construction type

classifications used by the International Building Code (IBC) and NFPA 220 do not exactly match,

type for type. The National Fire Protection Association is consistent, however, within its different

standards; therefore, the construction type classifications in NFPA 5000 and NFPA 220 are

identical. Table B.12-1 provides an approximate comparison. A notational system was developed

to identify the fire resistance required for the three basic elements of the building. These elements

are (1) the exterior wall, (2) the primary structural frame, and (3) the floor construction. A three-digit

notation was developed, as follows:

(1) First digit: Hourly fire resistance requirement for exterior bearing wall fronting on a street

or lot line.

(2) Second digit: Hourly fire-resistance requirement for a structural frame or columns and

girders supporting loads from more than one floor.

(3) Third digit: Hourly fire resistance requirement for floor construction.

Thus, for example, a “332” building would have 3-hour fire-resistant exterior bearing walls, a 3-hour

fire resistant structural frame, and 2-hour fire-resistant floor construction, and would correspond to

the NFPA 220 Type I (332) building and the International Building Code (IBC) Type IA building.

Table B.12-1. Construction Classifications of the Model Codes and NFPA 220

NFPA 220 &

NFPA 5000

 I I II II II III III IV V V

 443 332 222 111 000 211 200 2HH 111 000

IBC

Table 601 

 - IA IB IIA IIB IIIA IIIB IV VA VB

B.12.4 Reference

NFPA 220, “Standard on Types of Building Construction,” National Fire Protection Association,

Quincy, Massachusetts, 1999 Edition.

International Building Code, Sixth Edition, International Code Council, Inc., Falls Church, Virginia.

NFPA 5000, “Building Construction and Safety Code,” 2003 Edition, National Fire Protection

Association, Quincy, Massachusetts.
B-39

B.13 Deep-Seated Fires in Class A Solid Materials

B.13.1 General Information

Two types of fires can occur in Class A (ordinary) combustibles materials (e.g., wood, cloth, paper,

rubber, and many plastics including cable insulation). In the first type, commonly known as flaming

combustion, the source of combustion is volatile gases resulting from heating or decomposition of

the fuel surface. In the second type, commonly called smoldering or glowing combustion oxidation

occurs at the surface of, or within, the mass of fuel. These two types of fires frequently occur

concurrently, although one type of burning may precede the other. For example, a wood fire may

start as flaming combustion and become smoldering as burning progresses. Conversely,

spontaneous ignition in a pile of oily rags may begin as a smoldering fire and break into flames at

some later time (Friedman, 1997).

Smoldering combustion cannot be immediately extinguished like flaming combustion. This type of

combustion is characterized by a slow rate of heat loss from the reaction zone. Thus, the fuel

remains hot enough to react with oxygen, even though the rate of reaction, which is controlled by

diffusion processes, is extremely slow. Smoldering fires can continue to burn for many weeks, for

example in bales of cotton and jute and within heaps of sawdust or mulch. A smoldering fire

ceases to burn only when all of the available oxygen or fuel has been consumed, or when the

temperature of the fuel surface becomes too low to react. These fires are usually extinguished by

reducing the fuel temperature, either directly by applying a heat absorbing medium (such as water),

or indirectly by blanketing the fuel with an inert gas. In the latter case, the inert gas slows the rate

of reaction to the point at which heat generated by oxidation is less than the heat lost to the

surroundings. This causes the temperature to fall below the level necessary for spontaneous

ignition following removal of the inert gas atmosphere.

Smoldering fires are divided into two classes, in which the fire is either deep-seated or not.

Basically, “deep-seated” implies the presence of sub-surface smoldering combustion that may

continue for some time after surface flaming is suppressed. Deep-seated fires may become

established beneath the surface of fibrous or particulate material. This condition may result from

flaming combustion at the surface or from the ignition within the mass of fuel. Smoldering

combustion then progresses slowly through the mass. Whether a fire will become deep-seated

depends, in part, on the length of time it has been burning before the extinguishing agent is applied.

This time is usually called the “pre-burn” time (Nolan, 2001).

As described above, a deep-seated fire is embedded in the material being consumed by

combustion. To extinguish deep-seated fires, an individual must investigate the interior of the

material once the surface fire has been extinguished to determine whether interior smoldering has

also been extinguished by a gaseous agent. It should be noted, however, that the concentration

of the extinguishing agent must be adequate—and must be applied for an adequate duration—to

ensure that the smoldering has been effectively suppressed.
B-40

B.13.2 Deep-Seated Cable Fires

A deep-seated fire occurs in cables when the burning involves pyrolysing beneath the surface, in

addition to a surface phenomenon. This is postulated to occur when the cable fire reaches the

stage of a fully developed fire. Extinguishing a cable surface fire does not guarantee that a deepseated fire is also eliminated. A deep-seated fire is very difficult to suppress since fire suppressing

agent cannot easily get to the seat of the fire, and it is also difficult to detect since combustion is

primarily under the cooler surface.

Electrical cable fire tests have been conducted at the Sandia Fire Research Facility (Schmidt and

Krause, 1982) in order to evaluate cable tray fire safety criteria. A burn mode concept was

developed in order to describe and classify the thermodynamic phenomena which occur in the

presence of smoke and to compare the fire growth and recession of different cable types under

otherwise unchanged fire test conditions. The importance of deep-seated fires in cables trays from

the standpoint of propagation, detection, and suppression is emphasized. The cable tray fire tests

demonstrate that fire recession and deep-seated fires can result from a decreasing smoke layer

and that reignition and secondary fire growth is possible by readmission of fresh air.

B.13.3 Deep-Seated Charcoal Fires

The use of activated charcoal in NPPs presents a potential for deep-seated fires. Simply, that if

it says that it is combustible, that it may be ignited, and that if it does become ignited, it is likely to

become a deep-seated fire. It does not predict the frequency of those fires, nor form of ignition

(Holmes, 1987). On July 17, 1977, a fire occurred at the Browns Ferry Nuclear Power Plant (BFNP)

in Unit 3 off-gas system charcoal adsorber bed (Crisler, 1977). The elevation in adsorber bed

temperature caused temperature rises of sufficient magnitude to cause carbon ignition.

B.13.4 References

Crisler, H.E. Jr., “July 17, 1977, Off-Gas System Charcoal Adsorber Bed Fire at Browns Ferry

Nuclear Plant,” Proceedings of the CSNI Specialist Meeting on Interaction of Fire and Explosion

with Ventilation Systems in Nuclear Facilities, Volume II, Report Number: LA-9911-C, Vol.2; CSNI83, pp. 309-316, October 1983.

Friedman, R., “Theory of Fire Extinguishment,” Section 1, Chapter 8, NFPA Fire Protection

Handbook, 18 Edition, A.E. Cote, Editor-in-Chief, National Fire Protection Association, Quincy, th

Massachusetts, 1997.

Holmes, W., “Adsorber Fires,” Proceedings of the 19 DOE/NRC Nuclear Air Cleaning Conference,

th

NUREG/CP-0086-Vol. 2; CONF-860820-Vol.2, pp. 797-798, May 1987.

Nolan, D.P., Encyclopedia of Fire Protection, Delmar Publishers, Albany, New York, 2001.

Schmidt, W.H., and F.R. Krause, “Burn Mode Analysis of Horizontal Cable Tray Fires,” NUREG/CR2431, U.S. Nuclear Regulatory Commission, Washington, DC, February 1982.
B-41

B.14 Special Hazard Gaseous Fire Extinguishing Agents

B.14.1 Introduction

A gaseous (or gas phase) fire suppression agent remains in the gaseous state at normal room

temperature and pressure. It has low viscosity, can expand or contract with changes in pressure

and temperature, and has the ability to diffuse readily and distribute itself uniformly throughout an

enclosure. Gaseous fire extinguishing agents are categorized into two distinct classes, including

halocarbon and inert gases (such as nitrogen and mixtures containing argon). Halocarbon agents

(e.g., Halon 1301) act largely by absorbing although they also have some chemical effect on flame

combustion reactions. Inert agents contain unreactive gases that act primarily by oxygen depleting.

One important advantage of gaseous agents is that no cleaning is required if the agent is released

in the absence of a fire; a couple of minutes of venting is all that is required. However, gaseous

agents with the exception of Halon require a rather large storage area; this is particularly for

nitrogen and argon, which are usually stored as compressed gases.

Halogenated extinguishing agents are hydrocarbons in which one or more hydrogen atoms in an

organic compound (carbon) have been replaced by atoms from halogens (the chemicals in group

7 of the periodic table of the elements) chlorine (Cl), fluorine (F), bromine (Br), or iodine (I). This

substitution confers flame extinguishing properties to many of the resulting compounds that make

them useable for certain fire protection applications. The three halogen elements commonly found

in Halon extinguishing agents used for fire protection are fluorine, chlorine, and bromine.

Compounds containing combinations of fluorine, chlorine, and bromine can possess varying

degrees of extinguishing effectiveness, chemical and thermal stability, toxicity, and volatility. These

agents appear to extinguish fire by inhibiting the chemical chain reaction that promotes the

combustion process.

Carbon diox 2ide (CO ) has a long history as an extinguishing agent, which is primarily used for

2

flammable liquid fires and electrical equipment fires. CO is noncombustible and does not react

with most substances. It is a gas, but it can be easily liquified under pressure and is normally

2

stored as a pressure-condensed gas. CO provides its own pressure for release and blankets the

2

fire area when released in sufficient amounts. CO is extremely toxic since it replaces the oxygen

in the air; humans become unconscious at a 10-percent volume concentration followed by loss of

2

life. Therefore, CO cannot be released while people are present.

B.14.2 Halogenated Agent Extinguishing Systems

Halogenated extinguishing agents are currently known simply as Halons, and are described by a

nomenclature that indicate the chemical composition of the materials without the use of chemical

names. In this nomenclature the first digit of the number definition represents the number of carbon

atoms in the compound molecule; the second digit is the number of fluorine atoms; the third digit

is the number of chlorine atoms; the fourth digit is the number of bromine atoms; and the fifth digit

is if any, the number of iodine atoms.
B-42

For example, the number definition for the chemical composition of Halon 1301, perhaps the most

widely recognized halogenated extinguishing agent, is 1 (carbon), 3 (fluorine), 0 (chlorine),

1 (bromine), and 0 (iodine). This simplified system, proposed in 1950 by James Malcolm of the

U.S. Army Corps of Engineers Laboratory, avoids the use of possibly confusing names.

By contrast, the United Kingdom and parts of Europe still use the initial capital alphabet system

[i.e., bromotrifluoromethane (Halon 1301) is BTM and bromochlorodifuoro-methane (Halon 1211) is BFC].

Due to the many chemical combinations available, the characteristics of halogenated fire

extinguishing agents differ widely. It is generally agreed, however, that the agents most widely

used for fire protection applications are Halon 1011, Halon 1211, Halon 1301, Halon 2402, and (to

a lesser degree) Halon 122, which has been used as a test gas because of its economic

advantages. However, because of its widespread use as a test agent, many individuals have

wrongly assumed that Halon 122 is an effective fire extinguishing agent. Table B.14-1 illustrates

the halogenated hydrocarbons most likely to be used today. Of all of these types, however, the

most popular halogenated agent is Halon 1301, which offers superior fire extinguishing

characteristics and low toxicity. Because Halon 1301 inhibits the chain reaction that promotes the

combustion process, it chemically suppresses the fire very quickly, unlike other extinguishing

agents that work by removing the fire’s heat or oxygen. Stored as a liquid under pressure and

released as a vapor at normal room temperature, Halon 1301 readily spreads into blocked and

baffled spaces and leaves no corrosive or abrasive residue after use. A high liquid density permits

compact storage containers, which on a comparative weight basis, makes Halon 1301

app 2roximately 2.5 times more effective as an extinguishing agent than CO (Grand, 1995).

Table B.14-1. Halogenated Hydrocarbons Commonly Used for Fire Protection

Common Name Chemical Name Formula

Ha 3lon 1001 Methyl Bromide CH Br

Ha 3lon 10001 Methyl Iodide CH l

Ha 2lon1011 Bromochloromethane CH BrCl

Ha 2 2 lon 1202 Dibromodifluoromethane CF Br

Ha 2lon 1211 Bromochlorodifluoromethane CF BrCl

Ha 2 2 lon 122 Dichlorodifluoromethane* CF Cl

Ha 3lon 1301 Bromotrifluoromethane CF Br

Ha 4lon 104 Carbon Tetrachloride CCl

Ha 2 4 2lon 2402 Dibromotetrafluoroethane C F Br

* A popular test gas without substantial fire extinguishing properties.
B-43

Although halogenated agents may be applied using a variety of methods, the most common is the

total flooding system. According to the NFPA 12A, 1997 Edition, Section 2-3.1.1, a Halon 1301

total flooding system shall be automatically actuated for fires involving Class A ordinary combustible

materials (e.g., wood, cloth, paper rubber, and many plastics including cables), with the exception

that manual actuation shall be permitted if acceptable to the authority having jurisdiction (AHJ).

NFPA 12A, 1997 Edition, Section 3-7.1.2, also indicate that the agent discharge shall be

substantially completed in a nominal 10 seconds or as otherwise required by the AHJ. The rapid

discharge is specified to prevent the fire from becoming deep-seated, minimize unwanted

decomposition products, and achieve complete dispersal of the agent throughout the enclosure so

that the Halon quickly knocks down the flames and extinguishes the fire. When exposed to deepseated fires for long period of times, Halon 1301 decomposes into decomposition products, that

are toxic to personnel and corrosive to electronic components (See Section B.18 for further

discussion). Therefore, to extinguish fire effectively, while limiting the formation of hazardous

decomposition products, it is important to disperse the agent during the incipient stage of the fire.

A significant problem in using of Halon 1301 is that, in the normal firefighting concentrations of 5-

percent to 6-percent, it may fail to completely extinguish fires which originate in Class A solid

materials (e.g., wood, cloth, paper, rubber, and many plastics). External and visible flame is

instantly extinguished by Halon 1301, but internal and unseen flameless (but glowing) combustion

may continue. As defined by the NFPA, if a 5-percent concentration of Halon 1301 will not

extinguish a fire within 10 minutes of application, it is considered to be deep-seated, as described

above. Such deep-seated fires usually require concentrations much higher than 10-percent and

soaking times much higher than 10 minutes (NFPA 12A, 1971 Edition). The technical literature

does not provide any satisfactory explanation for the ineffectiveness of Halon 1301 in deep-seated

fires (Fielding and Woods, 1975).

Sandia National Laboratories (SNL) investigation of the effectiveness of the Halon 1301 fire

suppression agent on electrical cables fires in 1981 and again in 1986 at the behest NRC. These

full-scale fire suppression tests were performed to determine the concentration and minimum

soaking time necessary to suppress electrical cable tray fires and prevent reignition of those fires.

Halon 1301 was very effective in suppressing surface fires, but took much longer to suppress deepseated cable tray fires. The results of Test 60 depicted on Figure B.14-1 indicated that even after

Halon 1301 is discharged, the interior temperature of the cable bundle continues to rise, probably

as a resulting of continued combustion of the cable insulation. Moreover, a second increase in

temperature occurs, air is readmitted during ventilation, thereby causing reignition of the cable

insulation (Klamerus, 1981).

As illustrated in Figure B.14-1 the Halon 1301 concentration applied to the fire has a direct

relationship to the time required to completely extinguish the fire. When the agent is first applied

to the cable trays, the flames are immediately extinguished, but the deep-seated combustion

(or glow), continues and the fire will reignite if the enclosure is then ventilated.
B-44

Figure B.14-1 Indication of Deep-Seated Fire and Reignition of Cables, Test # 60, 

IEEE-383-Qualified Cables, Horizontal Trays, 4-Minute Halon Soak Acceptor

Tray Center Temperature (Klamerus, 1981)

B.14.2.1 Halon Concentration and Soaking Time

Soaking time is an important requirement for a Halon 1301 total flooding system. This is especially

true for Class A fires that may reflash. A minimum soaking period of 10-minutes is typically required

for fires in these applications, based on the full-scale total flooding fire suppression tests for

electrical cable tray fires conducted by Klamerus (1981), and Chavez and Lambert (1986).

A 6-percent Halon 1301 concentration with a 10-minute soak time successfully extinguished all

cable fires in horizontally and vertically oriented trays filled with IEEE-383 unqualified cables, while

IEEE-383 qualified cables required a 15-minute soaking time. The measure concentrations in these

tests were based on a completely air-tight enclosure during discharge (see Figure B.14-2 for Halon

1301 concentration requirements) with 15-minute soak time successfully extinguished all cable fires

in horizontal and vertical oriented tray filled. The measured concentrations in this testing are based

on completely tight enclosure during discharge and soaking time of Halon 1301 (see Figure B.14-2

for Halon 1301 concentration requirements).
B-45

Figure B.14-2 Soaking Time vs. Halon 1301 Concentration 

for Deep-Seated and Surface Fires

B.14.2.2 Agent Leakage

Because Halon 1301 is approximately five times heavier than air (with molecular weight 148.93

g/mol compared to 29 g/mol for air), there is a risk of Halon leakage from the protected space if the

space is not completely airtight. Therefore, it is important to know the Halon percent and soak time

at the highest combustible in the protected enclosure. NFPA 12A requires that the leakage rate

should be low enough so that the design concentration is held in the hazard area long enough to

ensure that the fire is completely extinguished. Reignition of the fire is a potential concern if the

effective concentration is not maintained. In case of leakage during and after discharge, a greater

amount of the agent is required to develop a given concentration. To maintain the agent

concentration at a given level requires continuous agent discharge for the duration of the soaking

period. The leakage rate from an enclosure could be predicted from the detailed knowledge of the

size, location, and geometry of any leaks. However, these details are rarely known, as leakage

may occur around doors and door seals; wall; ceiling; and floor cracks, duct, conduit, and cable

tray penetrations; and fire and isolation dampers. Appendix B to NFPA 12A presents methods of

estimating leakage area.
B-46

Discharging Halon 1301 into an enclosure to achieve total flooding results in an air/agent mixture

with a higher specific gravity than the air surrounding the enclosure. Therefore, any openings in

the lower portions of the enclosure will allow the heavier air/agent mixture to flow out and the lighter

outside air to flow in. Fresh air entering the enclosure will collect toward the top, forming an

interface between the air/agent mixture and fresh air. As the leakage proceeds, the interface will

descend toward the bottom of the enclosure. The space above the interface will be completely

unprotected, while the lower space will essentially contain the original extinguishing concentration.

Grant (1995) presented methods of adjusting the Halon 1301 concentration to unprotected

openings (leakage).

Rapid detection of a fire and prompt application of the extinguishing agent without outside

assistance can help to prevent a Class A fire from becoming deep-seated. If a fire becomes deepseated or (begins as a deep-seated fire), it will not likely be extinguished by Halon 1301

concentrations below 10-percent, and some deep-seated fires require concentrations above 18–30-

percent to ensure that the glow is completely extinguished (Grant, 1995).

It is important to remember that in most cases, halogenated agent extinguishing systems have only

a single chance to extinguish a fire. Such systems should be tested and Halon concentrations

measured at various heights within the protected space (at least at the point of the highest

combustible) to demonstrate the design concentrations. Timely and automatic actuation of Halon

systems would also provide reasonable assurance that a fire would be extinguished before

spreading through the combustible material and becoming deep-seated.

B.14.3 Carbon Dioxide Fire Extinguishing Systems

Carbon Diox 2ide (CO ) is a colorless, odorless, inert, and electrically nonconductive agent that

extinguishes a fire by displacing the normal atmosphere, thereby reducing the oxygen content

below 2 the 15-percent required for diffusion flame production. The CO from either low-pressure or

high-pressure extinguishing systems is stored and transported as a liquid through the piping system

2

to the nozzles. With the release of pressure at the nozzles, the liquid CO converts to a gas, with

some minute solid particles, making it approximately 50-percent heavier than air.

Flame ex 2tinguishment by CO is predominantly by a thermophysical mechanism in which reacting

gases are prevented from achieving a temperature high enough to maintain the free radical

population necessary for sustaining the flame chemistry. For inert gases presently used as fire

suppression agent (argon, nitrogen, carbon, carbon, and mixture of these), the extinguishing

concentration (as measured by the cup burner method, NFPA 2001) is observed to be linearly

related to the heat capacity of the agent-air mixture. Although of minor importance in accomplishing

2

fire suppression, CO also dilutes the concentration of the reacting species in the flame, thereby

reducing collision frequency of the reacting molecular species and slowing the rate of heat release.
B-47

CO2 fire extinguishing systems are useful in protecting against fire hazards when an inert,

electrically nonconductive, three-dimensional gas is essential or desirable and where clean up from

the agent must be minimal. According to the NFPA, some of the types of hazards and equipment

that carbon dioxide systems protect are “flammable liquid materials; electrical hazards, such as

transformers, switches, circuit breakers, rotating equipment, and electronic equipment; engines

utilizing gasoline and other flammable liquid fuels; ordinary combustibles such as paper, wood, and

textiles; and hazardous solids” (NFPA 12).

O 2ver the years, two methods of applying CO have been developed. The first technique is the total

2

flooding application, which involves filling an enclosure with CO vapor to a prescribed

2

concentration. In this technique, the CO vapor flows through nozzles that are designed and

located to develop a uniform concentration of the agent in all parts of the enclosure. The quantity

o 2f CO required to achieve an extinguishing atmosphere is calculated on the basis of the volume

of the enclosure and the concentration of the agent required for the combustibles material in the

enclosure. This technique is applicable for both surface-type fires and potentially deep-seated fires.

For surface-type fires, as would be expected with liquid fuels, the minimum concentration is 

34 2 2 -percent of CO by volume. Considerable testing has been done with using CO on liquid fuels

and appropriate minimum design concentrations have been derived at for a large number of

common liquid fire hazards.

Fo 2r deep-seated hazards, the minimum concentration is 50-percent of CO by volume. This

50-percent design concentration is used for hazards involving electrical gear, wiring insulation,

motors, and the like. Hazards involving record storage, such as bulk paper, require a 65-percent

2

concentration of CO , while substances such as fur and bag-type house dust collectors require a

75-percent concentration. It should be noted that most surface burning and open flaming will stop

when 2 the concentration of CO in the air reaches about 20-percent or less by volume. Thus, it

2

should be apparent that a considerable margin of safety is built into these minimum CO

2

concentrations required by the standard. This is because those who developed the CO standard

never considered it sufficient to extinguish the flame. By contrast, the guidelines given in some of

the standards for other gaseous extinguishing agents merely mandate concentrations that are

sufficient to extinguish open flame but will not produce a truly inert atmosphere.

The other 2 method of applying CO is local application. This method is appropriate only for

extinguishing surface fires in flammable liquids, gases, and very shallow solids where the hazard

is not enclosed or where the enclosure of the hazard is not sufficient to permit total flooding.

Hazards spray booths, printing presses, rolling mills, and the like can be successfully protected by

a 2 local application system designed to discharge CO and direct the flow at the localized fire

ha 2zard. The entire fire hazard area is then blanketed in CO without actually filling the enclosure

to a predetermined concentration.
B-48

The integrity of the enclosure is a very important part of total flooding, particularly if the hazard has

a potential for deep-seated fire. If the enclosure is air tight, especially on the sides and bottom, the

CO2 extinguishing atmosphere can be retained for a long time to ensure complete extinguishment

of 2 the fire. If there are openings on the sides and bottom, however, the heavier mixture of CO and

air may rapidly leak out of the enclosure. If the extinguishing atmosphere is lost too rapidly, glowing

embers may remain and cause reignition when air reaches the fire zone. Therefore, it is important

to close all openings to minimize leakage or to compensate for the openings by discharging

add 2itional CO .

An ex 2tended discharge of CO is used when an enclosure is not sufficiently air tight to retain an

extinguishing concentration as long as needed. The extended discharge is normally at a reduced

rate, following a high initial rate to develop the extinguishing concentration in a reasonably short

time. The reduced rate of discharge should be a function of the leakage rate, which can be

calculated on the basis of leakage area, or of the flow rate through ventilating ducts that cannot be

shut.

Extended discharge is particularly applicable to enclosed rotating electrical equipment, such as

generators, where it is difficult to prevent leakage until rotation stops. Extended discharge can be

applied to ordinary total flooding systems, as well to the local application systems where a small

hot spot may require prolonged cooling.

B.14.3.1 Carbon Dioxide Requirements for Deep-Seated Fires (NFPA 12)

NFPA 2 12 recognizes two types of CO extinguishing systems. The first type is the high-pressure

CO2 2 system, and the second is a low-pressure CO system. The basic difference between the two

2

types lies in the method of storing the CO .

The high-pressure system utilizes the U.S. Department of Transformation (DOT) spun steel storage

cylinders, which are usually kept at room temperature. At an ambient temperature of 21 °C (70 °F),

the internal pressure in such a unit reaches 850 psi. These cylinders are available in capacities of

50, 75, or 100 pounds.

B 2y contrast, the low-pressure storage unit maintains the CO in a refrigerated pressure vessel with

a 2 typical storage temperature of -18 °C (0 °F) with a corresponding CO vapor pressure of 300 psi.

The refrigerated storage concept uses an American Society of Mechanical Engineers (ASME)

coded pressure vessel with a working pressure of 2,413 kPa (350 psi). Such units are available

in standard capacities from 1.25–60 tons. Larger units have also been made for special

applications.

This basic difference in storage configuration inspired different application and control methods for

the two types of systems. Since the maximum capacity of a high-pressure cylinder is 100 pounds

of 2 CO , most systems consist of multiple cylinders manifolded together to provide the required

quantity of agent. Each cylinder has its own individual discharge valve and, once opened, the

cylinder contents will completely discharge.
B-49

NFPA 12 requi 2res that the quantity of CO for deep-seated fires must be based on fairly air tight

enclosures. After the design concentration is reached, it shall be maintained for a substantial

period of time, but not less than 20-minutes. Any possible leakage shall receive special

consideration, because the basic flooding factor does not include any leakage allowance.

For deep-seated fires the design concentration shall be achieved within 7-minutes from the start

of discharge, but the rate shall be not less than that required to develop a concentration of

30-percent within 2 minutes. For surface fires, the design concentration shall be achieved within

1-minute from the start of discharge.

B.14.3.2 Personnel Protection from Carbon Dioxide

The CO2 that is used to extinguish the diffusion combustion may pose a threat to human life, and

NPP personnel must recognize and plan to cope with this threat

Human subject 2s exposed to low concentrations (less than 4-percent) of CO for up to 30-minutes,

dilation of cerebral blood vessels, increased pulmonary ventilation, and increased oxygen delivery

to the tissues were observed (Gibbs et al., 1943, Patterson et al., 1955). These results were used

by the United Kingdom regulatory community to differentiate between inert gas systems for fire

2

suppression that contain CO and those that do not (HAG, 1995). During similar low-concentration

exposure scenarios in humans, however, other researchers have recorded slight increases in blood

pressure, hearing loss, sweating, headache, and dyspnea (Gellhorn and Speisman, 1934, 1935;

Schneider 2 and Schulte, 1964). 6–7-percent CO is considered the threshold level at which harmful

effects become noticeable in human beings. At concentration above 9-percent, most people lose

2

consciousness within a short time. Since the minimum concentrations of CO in air used to

e 2xtinguish fire exceed 9-percent, adequate safety precautions must be designed into every CO fire

extinguishing system.
B-50

B.14.3.3 Harmful Effects of Carbon Dioxide Fire Suppression Systems

A 2s described above CO is lethal to humans at the minimum concentrations required to suppress

2

fires. Accidents involving the discharge of CO fire suppression systems have resulted in numerous

dea 2ths and injuries. Given its inherent hazard, CO should not be used in areas that are subject

to occupancy, except when the risk of fire is documented to be greater than the risk to personnel

and no viable suppression alternatives exist.

In land-based workplace environments, the Occupational Safety and Health Administration (OSHA)

2

regulates the use of CO . These regulations are provided in 29 CFR Parts 1910.160 and 1910.162,

which outline the requirements for general and gaseous fixed extinguishing systems, respectively.

De 2spite the fact that the concentration of CO needed to extinguish fires is above the lethal level,

OSHA does not 2 prevent the use of CO in normally occupied areas. (However, OSHA does

explicitly limit the use of chlorobromomethane and carbon tetrachloride as extinguishing agents

whe 2re employees may be exposed [29 CFR Part 1910.160 (b) (11)]. For CO systems, OSHA

2

requires a predischarge alarm for alerting employees of the impending release of CO when the

de 2sign concentration is greater than 4-percent (which is essentially true for all CO systems). This

predischarge alarm must allow sufficient time delay for personnel to safely exit the area prior to

discharge. Although it is speculative, it is likely that these regulations would confer adequate

protection only in the event of planned discharge, not accidental discharge. Accidental discharges

have occurred, however, in which adherence to regulations has provided personnel protection,

whereas some planned discharges have resulted in injury to personnel.

The U.S. Environmental Protection Agency (EPA) has published a report to provide information on

2

the use and effectiveness of CO in fire protection systems and describe incidents involving

inadvertent exposure of personnel to the gas (EPA430-R-00-02, 2000). The results of this

2

comprehensive review identify that from 1975 to the present, a total of 51 CO incident records were

located that reported a total of 72 deaths and 145 injuries resulting from accidents involving the

di 2 2 scharge of CO fire extinguishing systems. All the deaths that were attributed to CO were the

result of asphyxiation. Details about the injuries were generally not provided in the incident reports,

although some OSHA inspections listed asphyxia as the nature of the injury. Prior to 1975, a total

o 2f 11 incident records were located that reported a total of 47 deaths and 7 injuries involving CO .

Twenty of the 47 deaths occurred in England prior to 1963; however, the cause of these deaths is

un 2known. The remainder of this section presents representative examples of the hazards of CO

fire suppression systems:

• On July 28, 2000, a bank employee accidentally suffocated in a New York City bank vault

af 2ter pulling a fire alarm that flooded the space with CO . The bank employee was putting

stock receipts in the bank’s basement vault when she accidentally became locked inside.

Appa 2rently thinking she could get help by pulling a fire alarm, she instead activated a CO

fire extinguishing system that sucked air from the vault. She was taken to a local hospital

in extremely critical condition and was pronounced dead.
B-51

• On January 15, 1999, at 5:49 p.m., with the plant at full power, an inadvertent discharge of

2

the CO fire suppression system occurred in the Millstone Unit 3 cable spreading room

(CSR), which is located in the control building directly below the control room. The

actuation occurred when a non-licensed plant equipment operator trainee in the service

bui 2lding blew dust off a printed circuit board located in the CSR CO control panel, which

is located in the service building, rather than the control building. There were no plant

per 2sonnel in the CSR at the time of the discharge. Shortly after the discharge, CO was

found to have migrated down into the switchgear rooms located directly below the CSR.

Approximately 37-minutes after initiation, the licensee used a portable instrument to

mea 2sure the concentration of CO in one of the control building stairwells, which allows

access to the control room, the CSR, and the switchgear rooms. The reading was off-scale

h 2igh indicating that the CO concentration was in excess of 50,000 parts per million (ppm).

NRC Regu 2latory Guide 1.78 currently recommends a CO toxicity limit of 10,000 ppm.

On the basis of this indication, the licensee declared the area uninhabitable.

Approx 2imately 2 hours after the CO discharge, operators aligned the control building purge

2

system to remove CO from the switchgear rooms. The switchgear rooms were selected

for purging first because they contained important plant equipment, such as the auxiliary

2

shutdown panel. The purge system is a non-safety-related system designed to remove CO

and smoke from various control building areas. Placing the purge system in service

diverted air from the control room to the switchgear rooms, which reduced the pressure in

the control room relative to the CSR. This pressure reduction in the control room may have

a 2llowed CO from the CSR room to migrate up through penetrations into the control room.

When 2 the concentration of CO reached 5,000 ppm in the control room, the operators

donned self-contained breathing apparatus (SCBA), as required by the plant procedures.

The con 2centration of CO in the control room reached a peak level in excess of 17,000 ppm

before it began to decrease. The operators wore SCBA for approximately 6 hours until the

CO2 was successfully purged from the control room.

2

• On July 29, 1998, a high-pressure, total flooding CO extinguishing system discharged

without warning during routine maintenance of electrical equipment, resulting in one fatality

and several serious injuries in Building 648 of the Idaho National Engineering and

Environmental Laboratory (INEEL) (EH2PUB/09-98/01A1). At the time of the accident, the

new 2ly installed CO system releasing panel was electronically disabled and considered to

be out of service. The work crew began opening circuit breakers in preparation for the

prevent 2ive maintenance work. Shortly after the last breaker was opened, the CO system

discharge, creating near zero visibility. While the evacuation alarms may have briefly

2

sounded for less than one second, they did not continuously sound in conjunction with CO

2

release. After the CO discharge, the worker ran toward the exits, which were visible since

they were held open by cables running into the building from portable generators. Eight of

the workers were able to exit on their own; however, five remained inside of the building and

were rendered unconsc 2ious by the CO . Three were later rescued by the workers who had

earlier escaped, which left two people remaining in the building. One of the remaining

workers was later revived, and the other perished.
B-52

• At Duane Arnold Unit 1 on March 22, 1992 (LER 331/92-004), the licensee performed a

2

special test of the CO fire suppression system in the CSR. This test was conducted to

2

check corrective actions taken following a CO discharge in 1990. At the time of this test,

2

the reactor had been shut down and defueled. As a result of this test, CO intruded into the

control room, and this intrusion led to an unacceptable reduction in the oxygen level in the

area within a few minutes. The operator recorded oxygen levels of 17-percent (at chest

level) and 15-percent (at floor level), both of which were below the plant’s acceptance

criterion of 19.5-percent. Essential control room personnel donned SCBA and were able

to remain in the control room. The reduced oxygen levels resulted from increased pressure

in the CSR, which is directly beneath the control room. Sealed penetrations between the

two rooms leaked under the high differential pressure.

2

In this incident, the migration of CO into various fire zones may have adversely affected the

operators’ ability to shut down the plant during a fire in the CSR. Consequently, one can

conclude that a severe fire in the CSR may adversely affect the operators’ ability to safely

shut down the plant from the control room. In the event that the operators are required to

evacuate the control room, plant procedures require operators to shut down the plant from

the auxiliary shutdown panel and other panels, which are located in the switchgear rooms.

Du 2ring this event, the CO concentration at the auxiliary shutdown panel would prohibit

access without SCBA.

• At Surry Nuclear Power Station on December 9, 1986, an accidental discharge of both the

CO2 and Halon extinguishing systems was caused by water damage to the extinguishing

system control panels. The water came from a pipe break in the feedwater system. Four

died and four were injured in a fire associated with the accident. However, it is not clear if

the release of the gases from fire extinguishing systems were responsible for these injuries

and deaths (Warnick, 1986).

2

• At Hope Creek Generating Station, on September 4, 1984, a 10-ton CO system was

inadvertently discharged into a diesel generator fuel storage area. The warning bell and

beacon light did not operate and workers who were cleaning the corridor walls outside of

the fuel storage room with air/water guns under pressure were not alerted. The cause of

2

the discharge was determined to be moisture (that entered the CO control panel through

open 2ings at the top of an inadequately installed protective panel) that shorted the CO

control panel circuitry. The moisture was believed to have originated from the workers

cleaning the corridor walls (PNO-I-85-64a).
B-53

B.14.4 References

Chavez, J.M., and L.D. Lambert, “Evaluation of Suppression Methods for Electrical Cables Fires,”

NUREG/CR-3656, U.S. Nuclear Regulatory Commission, Washington, DC, October 1986.

EPA430-R-00-02, “Carbon Dioxide as a Fire Suppressant: Examining the Risk,” U.S. Environmental

Protection Agency, Office of Air and Radiation, Stratospheric protection Division, Washington DC,

February 2000.

Fielding, G.H., and F.J. Woods, “Halon 1301: Mechanism of Failure to Extinguish Deep-Seated

Fires,” Journal of Fire & Flammability, Volume 6, pp. 37–43, January 1975.

Gel 2lhorn, E., and I. Spiesman, “Influence of Variations of O - and Carbon Dioxide Tension in the

Inspired Air Upon Hearing,” Proceedings of Society of Exp. Biol. Med., Volume 32, pp. 46–44,

1934.

Gellhorn, E., and I. Spiesman, “Influence of Hyperpnea and Variations of O2- and CO2-Tension in

the Inspired Air Upon Hearing,” American Journal of Physiology, Volume 112, pp. 519–528, 1935.

Gibbs, F.A., E.L Gibbs, E.G. Lennox, and L.F. Nims, “The Value of Carbon Dioxide in Counteracting

the Effects of Low Oxygen,” Journal of Aviat. Med., Volume 14, pp, 250–261, 1943.

Grand, C.C., “Halon Design Calculations,” Section 4, Chapter 6, SFPE Handbook of Fire

Protection Engineering, 2 Edition, P.J. DiNenno, Editor-in-Chief, National Fire Protection nd

Association, Quincy, Massachusetts, 1995.

HAG, “A Review of the Toxic and Asphyxiating Hazards of Clean Agent Replacements for Halon

1301,” Prepared by the Halon Alternatives Group (HAG) in the UK, February 1995. As Cited in a

Letter dated May 9, 1995 from J.S. Nicholas, Ansul Inc., to Karen Metchis, EPA.

Klamerus, L.J., “Electrical Cable Fire Suppression Tests with Halon 1301,” SAND 81-1785, Sandia

National Laboratories (SNL), Albuquerque, New Mexico, August 1981.

NFPA 12, “Carbon Dioxide Extinguishing Systems,” National Fire Protection Association, Quincy,

Massachusetts.

NFPA 12A, “Standard on Halon 1301 Fire Extinguishing Systems,” 1992 Edition, National Fire

Protection Association, Quincy, Massachusetts.

NFPA 12A, “Standard on Halon 1301 Fire Extinguishing Systems,” 1971 Edition, National Fire

Protection Association, Quincy, Massachusetts, pp. 59–69.
B-54

NFPA 2001, “Standard on Clean Agent Fire Extinguishing Systems,” 2000 Edition, National Fire

Protection Association, Quincy, Massachusetts.

NRC Information Notice: 99-05, “Inadvertent Discharge of Carbon Dioxide Fire Protection System

and Gas Migration, March 8, 1999.

Patterson, J.L., H. Heyman, L.L Battery, and R.W. Ferguson, “Threshold of Response of the

Cerebral Vessels of Man to Increases in Blood Carbon Dioxide,” Journal of Clin. Invest, Volume 34,

pp. 1857–1864, 1955.

Preliminary Notification of Event or Unusual Occurrence PNO-I-99-004: Carbon Dioxide Discharge

into Cable Spreading Room, Millstone Unit 3. January 20, 1999.

Preliminary Notification of Event or Unusual Occurrence - PNO-I-85-64a, U.S. Nuclear Regulatory

Commission Region I, September 5, 1985.

Schult, J.H., “Sealed Environments in Relation to Health and Disease,” Arch. Environment Health,

Volume 8, pp. 438–452, 1964.

Sinclair, R.D., J.M. Clark, and B.E. Welch, “Comparison of Physiological Responses of Normal man

to Exercise in Air and in Acute and Chronic Hypercapnia,” Underwater Physiology,

C.J. Lambertsen, Editor, Academic Press, New York, New York, pp. 409–417, 1971.

“Type A Accident Investigation Board Report of the July 28, 1998, Fatality and Multiple Injuries

Resulting from the Release of Carbon Dioxide at Building 648, Test Reactor Area,” Idaho National

Engineering and Environmental Laboratory, U.S. Department of Energy, EH2PUB/09-98/01A1,

September 1998.

Warnick, L., “Inadvertent Actuation of Fire Suppression Systems, Surry Nuclear Power Station,

Feedwater Pipe Failure,” Virginia Power, Richmond, Virginia, 1986.
B-55

B.15 Dry Chemical Extinguishing Agents

Dry chemicals or powders, or solid phase agents provide an alternative to water or gaseous agents

for extinguishing fire. Table B.15-1 lists the chemical names, formulae, and (commercial) names

of the various dry chemical agents. In each case, the particles of powder (10–76 m in size) are

coated with an agent (such as zinc stearate or a silicone) to prevent caking and promote flowing,

and are projected by an inert gas. The effectiveness of any of these agents depends on the particle

size. The smaller the particles, the less agent is needed as long as particles are larger than a

critical size. The reason for this fact is believed to be that the agent must vaporize rapidly in the

flame to be effective. However, if an extremely fine agent were used, it would be difficult to

disperse and apply to the fire.

Table B.15-1. Dry Chemical Agents

Chemical Name Formula Popular Name(s)

Sodium 3 bicarbonate NaHCO Baking soda

Sodium chloride NaCl Common salt

Potass 3ium bicarbonate KHCO Purple K

Potassium chloride KCl Super K

Po 2 4 tassium sulfate K SO Karate Massive

Monoammonium 4 2 4 phosphate (NH )H PO ABC or multipurpose

U 2 2 3rea and Potassium bicarbonate NH CONH + KHCO Monnex

It is difficult to draw a precise comparison of effectiveness of one dry chemical with another

because a comparison based on chemical differences would require each agent to have identical

particle size. Furthermore, gaseous agents can be compared by studying the flammability limits

of uniform mixtures at rest; however, if particles were present, they would settle out unless the

mixture is agitated, thus modifying the combustion behavior. Nonetheless, some general

comparisons of various powders have been made:

• Sodium bicarbonate (standard dry chemical) and sodium chloride have comparable

effectiveness and are several times as effective (on a weight basis) as powders such as

limestone or talc, which are supposedly chemically inert in a flame. Sodium bicarbonate

(standard dry chemical) primarily consists of sodium bicarbonate (over 90-percent) with

additives to improve fluidity, non-caking, and water-repellent characteristics.

• Potassium bicarbonate or potassium chloride is up to twice as effective (on a weight basis)

as the corresponding sodium compounds.
B-56

• Under some conditions, monoammonium phosphate is more effective than potassium

bicarbonate, however, it can be less effective under other conditions.

• Monnex is twice as effective as potassium bicarbonate because of the rapid thermal

decomposition of the complex formed between urea and potassium bicarbonate, which

cause a breakup of the particles in the flame to form very fine fragments, which then rapidly

gasify.

Dry chemical formulations may be ranked with regard to their effectiveness in extinguishing fires

according to their performance in tests. As previously described, this performance is a function of

both the chemical composition and the particle size. It seems clear that the effective powders act

on a flame through some chemical mechanism, presumably forming volatile species that react with

hydrogen atoms or hydroxyl radicals. However, science has not yet firmly established the precise

reactions. Although the primary action is probably removal of active species, the powders also

discourage combustion by absorbing heat, blocking radiative energy transfer, and in the case of

monoammonium phosphate, forming a surface coating.

Of the seven types of dry chemicals commonly in use, only monoammonium phosphate is

considered effective against deep-seated fires because of a glassy phosphoric acid coating that

forms over the combustible surface. All seven types of dry chemical extinguishing agents act to

suppress the flame of a fire (Friedman, 1998), but require significant cleaning after use. As a result

their use is limited almost exclusively to environments where this is not a serious concern. Dry

chemicals are very common in manual extinguishers and to some extent for local applications. The

most common application of these agents is for relatively small flammable liquid fires. Dry chemical

total flooding suppression systems are designed to reach the design concentration within the entire

protected volume in less than 30 seconds (NFPA 17, “Standard for Dry Chemical Extinguishing

System”). Additional dry chemical is required to compensate for losses attributable to openings and

ventilation in a compartment.

One reason for the popularity of dry chemical extinguishing agents other than monoammonium

phosphate has to do with corrosion. Any chemical powder can produce some degree of corrosion

or other damage, but monoammonium phosphate is notably acidic and corrodes more readily than

other dry chemicals, which are neutral or mildly alkaline. Furthermore, corrosion by the other dry

chemicals is stopped by a moderately dry atmosphere, while phosphoric acid has such a strong

affinity for water that an exceedingly dry atmosphere would be needed to stop corrosion.

Monoammonium phosphate is also not recommended for kitchen fires involving hot fat because of

its acidic nature; an alkaline dry chemical (such as potassium bicarbonate) is preferred.

Application of a dry chemical extinguishing agent on an electrical fire is safe (from the viewpoint of

electric shock) for fire fighters. However, these agents (especially monoammonium phosphate) can

damage delicate electrical equipment.
B-57

B.15.1 Hazards Associated with Dry Chemicals

One hazard associated with the use of dry chemical extinguishing agents is attributable to the

sudden release of the agent. Another hazard is unexpected reignition. The main toxic hazards

following the use of dry chemical agents will generally be those attributable to the combustion

processes, since dry chemicals themselves are non-toxic. According to Hague (1997), the

ingredients used in dry chemical agents are nontoxic but can cause temporary breathing difficulty

and can interfere with visibility.

B.15.2 References

Friedman, R., Principles of Fire Protection Chemistry and Physics, 3 Edition, Chapter 14, “Fire- rd

Fighting Procedures,” National Fire Protection Association, Quincy, Massachusetts, pp. 229–230,

1998.

Hague, D.R., “Dry Chemical Agents and Applications Systems,” Section 6, NFPA Fire Protection

Handbook, 18 Edition, National Fire Protection Association, Quincy, Massachusetts, 1997. th

NFPA 17, “Standard for Dry Chemical Extinguishing Systems,” 2002 Edition, National Fire

Protection Association, Quincy, Massachusetts.
B-58

B.16 Fire Protection Using Foam

Extinguishing foams provide a primary alternative to water, particularly for large fires. Foams are

widely used to control and extinguish fires involving flammable and combustible Class B liquids

(e.g., solvents, oil-based paints, petroleum greases, paraffin or heavy lubricants, tars, lacquers,

hydrocarbons, alcohols, LPG, LNG, and cooking fats). Foams are also suitable for Class A fires

involving ordinary combustible materials (e.g., wood, cloth, paper, rubber, and many plastics).

If a flammable liquid is lighter than water and is insoluble in water, application of water to extinguish

a fire would simply cause the liquid to float on the water and continue to burn. Moreover, if the

burning liquid is an oil or fat, the temperature of which is substantially above the boiling point of

water, the water will penetrate the hot oil, turn into steam below the surface, and cause an eruption

of oil (boilover) that will accelerate the burning rate and possibly spread the fire. By contrast, if the

flammable liquid is water soluble (such as alcohols), addition of sufficient water will dilute the liquid

to the point where it is no longer flammable. However, if the fire involves a deep pool of alcohol

(rather than a shallow spill), the time required to obtained sufficient dilution might be so great that

an aqueous foam would be a better choice of extinguishing agent. If the nature of a liquid is

unknown, an aqueous foam might still be chosen over direct application of water. Another

important application of foam is on liquids or solids that are burning in spaces that are difficult to

assess (such as a room in a basement or the hold of a ship). In such instances, the foam is used

to flood the compartment completely.

Fire-fighting foam is a mass of bubbles formed by various methods from aqueous solutions of

specially formulated foaming agents. Some foams are thick and viscous, forming tough heatresistant blankets over burning liquid surfaces and vertical areas. Other foams are thinner and

spread more rapidly. Some are capable of producing a vapor-sealing film of surface-active water

solution on a liquid surface, and others are meant to be used as large volumes of wet gas cells to

inundate surfaces and fill cavities. The foam initially acts as a blanketing agent and then as a

cooling agent as the water drains from the foam, as a cooling agent.

The effectiveness of foam is attributable to the following factors:

• prevents air from reaching fire

• generates steam, which dilutes the air as well as absorbed heat

• penetrates crevices because of low surface tension

• provides protection of exposed material that not yet burning

Nonetheless, foam is an unstable air-water emulsion, which can easily be broken down by physical

or mechanical forces, and certain chemical vapors or fluids can quickly destroy foam.

Consequently, when certain other extinguishing agents are used in conjunction with foam, severe

breakdown of the foam can occur. In addition, turbulent air or violently uprising combustion gases

can divert light foam from the burning area.
B-59

Foam breaks down and vaporizes its water content under attack by heat and flames. Therefore,

it must be applied to a burning surface in sufficient volume and at a sufficient rate to compensate

for this loss and guarantee a residual foam layer over the extinguished portion of the burning liquid.

The process of foam spread over a burning liquid fuel is similar to the spread of a less dense liquid

(such as oil) on a more dense liquid (such as water).

B.16.1 Properties of Foam

Foams used for fire fighting should possess certain general properties, including (1) expansion,

(2) cohesion, (3) stability, (4) fluidity, (5) fuel resistance, and (6) resistance. Clearly, foam

extinguishing agents must have an appreciable expansion ratio, the bubbles must adhere together

to form a blanket, and the foam must retain its water and remain stable, flowing while freely over

the liquid surface and around any obstacles. In addition, foam agents must not pick up so much

fuel that the foam would be liable to burn, and the agent must resist the heat of flames on the liquid.

Foams for use on alcohol fires must also be alcohol resistant.

Three quantitative criteria for foam are (1) the expansion (2) the fluidity and (3) the drainage time.

Expansion is quantitatively measured by the expansion ratio. While fluidity is measured in terms

of shear stress. A shear stress in the range 150–200 dyn/cm , measured on a torsional viscometer, 2

is typical of a good foam extinguishing agent. The drainage of liquid out of the foam is usually

expressed as the 25-percent drainage rate, which is the time in minutes for 25-percent of the total

liquid content to drain away under standard conditions. For a good foam, this drainage time is

typically 2–5 minutes.

Foam extinguishing agents can also be affected by the quality of the water used. A study by Dimaio

and Lange (1984) detected deleterious effects from contaminants (such as corrosion inhibitors, antifouling agents, etc.). In general, however, such effects were found to be much weaker if high

application rates were used.
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B.16.2 Hazards Associated with Foam

Foam is water-based; consequently, hazards associated with water also apply to foam. These

hazards include increased vaporization of low-boiling flammable combustible liquids, reaction with

incompatible materials and electric shock from live electrical equipment. Another hazard is rupture

of the foam blanket and burn back, which may put fire fighters at risk. Hazards can also arise from

the use of a foam on a liquid at a temperature of 100 °C (212 °F) or above, because the formation

of steam can cause a four-fold expansion of the foam with boilover of the burning liquid. In the case

of the medium- and high-expansion foams used to fill spaces, there is the additional hazard of

asphyxiation of personnel or visibility and spacial limitations resulting in injury.

Another hazard of foam is ignition of hydrocarbons in a storage tank roof by static electricity from

foam injection, as described by Howells (1993). This author describes several incidents in which

ignition of volatile refined products in a floating roof storage tank appears to have been caused by

foam injection. He suggests two possible modes of charge generation, including (1) the setting of

water droplets through the hydrocarbon liquid and (2) the streaming current of the foam mixture

leaving the nozzle.

B.16.3 Delivery Systems for Foam

Foam is delivered to a fire by means similar to those used for water, which primarily include fixed

systems such as foam-water spray systems and fixed foam-water monitors, and mobile foam-water

systems such as fire hoses. For low-expansion foam, one type of fixed-foam system used for lowexpansion foam is the foam-water deluge system. Fixed-foam systems are used for fire prevention,

extinguishment, and control in bunds or on spills. Subsurface application of low-expansion foam

to hydrocarbon storage tanks was developed in the 1960s and is now an NFPA-recognized design

procedure. Relevant codes are NFPA 11, “Standard for Low-Expansion Foam”; NFPA 11A,

“Standard for Medium-and High-Expansion Foam Systems”; and NFPA 16, “Standard for the

Installation of Foam-Water Sprinkler and Foam-Water Spray Systems.” There is limited use of foam

in portable devices except in wildland fire situations involving Class A fuels. The Class A foams

are generally mixed in 0.1% to 1.0% concentration ratios in water and are utilized in compressed

air/foam systems which discharge through hose lines equipped with air aspirating foam nozzles or

conventional fog nozzles.

The delivery of foam involves three stages, including (1) proportioning the foam concentrate,

(2) generating foam, and (3) distributing foam. There are a number of methods for proportioning

the foam concentrate. The devices for generating the foam are incorporated in the devices used

for its distribution, as previously described. The basic generation method is aspiration of air into

the foam.
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B.16.4 Application of Foam

Fire extinction by blanketing may be achieved using foam. Foam can be used for all modern fire

protection in warehouses, high storage areas, and process plants of all types for commodities such

as rubber tires, rolled paper, and plastics; in bulk storage areas and conveyor tunnels, coal mines,

coal handling equipment tunnels, and diked areas; in electric power plants aircraft hangars, and

aboard ships. An example of application in a BWR is the use of a foam water sprinkler system

(NFPA 16) to protect the large oil hazard of the recirculation pumps motor generator (MG) set.

Low expansion foam is mainly used to prevent, extinguish, or control fires in storage tank tops and

bunds and on spills. Medium- and high-expansion foams are used to prevent, extinguish, or control

fire in spaces such as fires below grades (e.g., basement).

Foam should be used only if compatible with the hazardous liquid. In particular, foam is essentially

expanded water and, apart from its density, has the general characteristics of water. Consequently,

it is just as unsuitable as water for fighting fires involving electrical equipment or substances that

have undesirable reactions with water. Other prerequisites for the use of foam are that the liquid

surface must be horizontal and the temperature of the liquid must be below the boiling point. In

addition, the liquid temperature is below the boiling point of the given hazardous liquid, but above

100 °C (212 °F), water in the foam will turn to steam, which can result in very large expansion of

the foam.

There are optimum rates of foam application. For low-expansion foam with an expansion ratio of

8:1, an application rate of 0.1 US gal/ft -min will give 0.8 US gal/ft -min of foam. Application 2 2

systems for medium- and high-expansion foams comprise both (1) total flooding systems and

(2) local application systems. Fighting a major fire requires a very large quantity of foam.

An example quoted by Nash (1966) is a requirement of 300 x 5 UK gal drums for a 30-minute foam

attack on a single 150-ft diameter oil storage tank. The supply and disposal of such a large number

of drums in an area congested with appliances and hoses constitute a major problem.

Consequently, Nash describes the alternative of providing a piped supply of foam concentrate.

A particularly important application of foam is the protection of storage tanks. For fixed roof tanks,

some principle arrangements are foam chambers, internal tank distributors, and subsurface foam

injection. Foam chambers are installed at intervals on the outside near the top of the tank wall,

providing an over-the-top foam generation. An alternative is internal distributors fitted inside the

tank. Application of foam at the top of the tank poses several problems. If the fire is initiated by

an explosion, the explosion itself may also disable the foam system. The upward flow of air caused

by the fire may also interfere with the distribution of the foam and the foam may not reach the center

of a large tank. Subsurface foam injection is designed to counter these difficulties. Such systems

inject under pressure up through the liquid in the tank. Injection may be through the product pipe

or a dedicated line. Mobile foam trucks may be used to provide the foam supply.
B-62

Floating roof tanks may be open topped or closed. Both have a good fire record, so foam systems

are generally not required. The one exception to this rule is the need to allow for rim fires, which

can occur on either type of tank. An open-topped floating roof tank may be protected by a fixed

foam system, which pours foam into the annulus formed by the tank wall and a foam dam. A closed

floating roof tank may be protected using a top injection system similar to those used in fixed roof

tanks. Subsurface foam injection is not generally used for floating roof tanks, since a tilted or

sunken roof can cause poor foam distribution.

Foam trucks are the principal means of mobile foam of delivery. The trucks are typically purposebuilt twin-agent trucks with the capability to deliver dry chemicals in addition to aqueous film forming

foam (AFFF). Foam trucks carry a supply of foam concentrate and delivery hoses and can be

equipped with telescoping booms or articulated towers. They also have low clearances to allow

passage under pipe bridges. Monitor capacities are on the order of 500–1000 US gal-min.

A variety of mobile devices can be used to apply foam to the top of a storage tank that is on fire.

These include mobile foam monitors and foam towers. However, using a foam monitor for this

purpose poses numerous problems, such as crosswinds and fire updrafts, which can waste a

significant proportion of the foam.

Use of foam extinguishing agents is not limited to fire control and extinguishment. Another

important application is the suppression of vaporization from toxic liquid spills. This use of foam

is treated in ASTM F1129-88, “Standard Guide for Using Aqueous Foams to Control the Vapor

Hazard from Immiscible Volatile Liquids.” A 500 to 1 foam ratio can be used to control fires and

reduce vaporization from liquefied natural gas (LNG) spills.

B.16.5 Types of Foam

A large family of foams of different types and applications are currently available. Water-based

foams are available in the following forms:

• chemical foam

• protein-based mechanical foam

— standard low-expansion foam

— high-expansion foam

— medium-expansion foam

• special foam

— fluorochemical for light-water foam

— fluoroprotein foam

• synthetic detergent foam

— aqueous film-forming foam (AFFF)

— film-forming fluoroprotein (FFFP) foam

— alcohol-resistant foam

— low-temperature foam
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One broad distinction is the viscosity of the foam. The blanket formed by the more viscous type is

resistant to rupture by flame, but the less viscous type flows more readily over a liquid surface.

• Chemical Foam

Chemical foam is produced by reacting an aqueous solution of sodium bicarbonate and

alum 2inum sulphate in the presence of a foam stabilizer. The reaction generates CO , which

both forms foam and ejects the mixture from the apparatus. This type of foam may be

generally regarded as obsolete, given that its use has long been almost entirely confined

to chemical foam portable extinguishers which are no longer listed by Underwriters

Laboratories.

• Protein-Based Mechanical Foam

— Mechanical foam is generated by mechanical aeration of aqueous solutions of

certain chemicals, which usually have a protein base. For example, one type is

based on protein rich slaughter house byproducts for the foam stabilizing agent.

Standard foam is made by introducing the foam compound into the water in the

hose to give a 3–6-percent aqueous solution and then mixing the solution with air

in an ejector nozzle to give an expansion of approximately 10:1. This type of foam

is the most widely used for both fixed and mobile apparatus. Such standard lowexpansion foam is often very economical.

— High-expansion foam is generally similar to standard foam, with the exception that

it has a much higher expansion of approximately 1,000:1. Because this type of

foam contains little water, it acts almost entirely by blanketing rather than cooling.

In addition, it is very light and become easily blown away, it is more suitable for fires

in contained spaces than for those in open situations (such as bunds).

— Medium-expansion foam is also generally similar to standard foam, with the

exception that has an expansion of approximately 100–150:1. This type of foam

is also light, but is not so easily blown away as high-expansion foam. Both mediumand high-expansion foams have a good three-dimensional extinction capability and

can be used against fires on piles of materials (such as rubber).

A disadvantage of protein foams is that if the foam blanket is broken, the liquid may

reignite and burn back the blanket. Low-expansion foam, however, has an

advantage in this regard, given that it has reasonably good heat and burnback

resistance.

• Special Foam

— Fluorochemical or Light-Water Foam

Fluorochemical foam is one agent that has been developed to overcome the

problem of reignition and burnback. One type is fluorochemical foam. This lightwater foam contains a straight-chain fluorocarbon surface active agent. This has

the effect that as the water drains from the foam, it spreads in a thin film over the

liquid and seals it. Even if the film is disturbed by agitation, it reforms rapidly. Lightwater foam behaves differently, however, on different liquids, and it is expensive and

not universally effective.
B-64

— Fluoroprotein Foam

Another agent that works in a manner similar to fluorochemical light-water foam is

fluoroprotein foam, which contains a branched-chain fluorocarbon. Where good

burnback resistance is needed, this alternative is less expansive and appears (in

many cases) to be more effective than light-water foam. In particular, fluoroprotein

foam is less prone to pick up oil particles when passed through oil. This fuelshedding property is useful in subsurface foam injection on storage tanks. This type

of foam also tends to have good compatibility with dry chemicals.

! Synthetic Detergent Foam

Synthetic detergent foam is generated by mechanical aeration of an aqueous solution

containing 2–3 -percent detergent. This foam is less stable than protein-based foam, but

it appears to be useful in massive application in a knockout attack. Despite its limitations,

detergent foam has enjoyed some popularity, because it is even less expensive than protein

foam.

— Aqueous Film-Forming Foam (AFFF)

AFFF has low viscosity and spreads easily over a liquid surface so it can be an

effective agent against deep-seated fires. Another useful property of AFFF is that

it does not need elaborate foaming devices and can be used in many water sprinkler

and water spray systems.

— Film-Forming Fluoroprotein (FFFP) Foam

FFFP foam is another type of foam that has low viscosity and good spreading

properties and can be used in many water spray systems. FFFP foam tends to

drain rapidly and, therefore, is less reliable in maintaining a foam blanket.

— Alcohol-Resistant Foam

Regular air foams do not perform well on liquids that are of the polar solvent type

(notably alcohol). Alcohol-resistant foams have been developed to solve that

problem. The first generation of alcohol-resistant foams were not entirely

satisfactory, but effective foams have since been developed. One type of alcoholresistant foam is polymeric-alcohol resistant AFFF.

— Low-Temperature Foam

Foams have been developed for use at low ambient temperatures; one quoted

temperature for such foams is -29 °C (-20 °F). These foams come in both protein

and AFFF types.
B-65

B.16.6 References

Dimaio, L.R., and R.F. Lange, “Effect of Water Quality on Fire Fighting Foams,” Plant/Operations

Progress, Volume, 3, 1984.

Friedman, R., Principles of Fire Protection Chemistry and Physics, 3 Edition, National Fire rd

Protection Association, Quincy, Massachusetts, 1998.

Howells, P., “Electrostatic Hazards of Foam Blanketing Operations,” Health, Safety and Loss

Prevention, p. 312, 1983.

Nash, G., “New Concept in the Supply of Foam Compound to Oil Fires,” Fire International, Volume

1, No. 12, p. 40, 1966.

NFPA 11, “Standard for Low-Expansion Foam,” 2002 Edition, National Fire Protection Association,

Quincy, Massachusetts.

NFPA 11A, “Standard for Medium-and High-Expansion Foam Systems,” 1999 Edition, National Fire

Protection Association, Quincy, Massachusetts.

NFPA 16, “Standard for the Installation of Foam-Water Sprinkler and Foam-Water Spray Systems,”

1999 Edition, National Fire Protection Association, Quincy, Massachusetts.

NFPA 1150, “Fire Fighting Chemicals for Class A Fuels in Rural, Suburban, and Vegetated Areas,”

1999 Edition, National Fire Protection Association, Quincy, Massachusetts.

B.16.7 Additional Reading

Woodworth, S.P., and J.A. Frank, Fighting Fire with Foam, Van Nostrand Reinhold, New York,

1994.
B-66

B.17 Harmful Properties of Toxic Gases Found in Fires

B.17.1 Introduction

Historically, more people are injured or killed by fire combustion products than by direct exposure

to heat and flame. Evaluations have shown that personnel at a distance from the source of a fire

are particularly at risk from fire effluent in post-flashover fire scenarios (Beitel et al., 1998). Toxic

gases are lethal largely because they cause people to become disoriented and suffer respiratory

distress, often losing consciousness and physical mobility. Following a period of hyperventilation,

resulting from inhaling irritant gases the final cause of death is often carbon monoxide (CO)

poisoning or scorching of the lungs by hot fire gases, rather than thermal exposure or flame impact.

The most significant effluent toxicants in ordinary fires are CO, hydrogen cyanide (HCN), carbon

d 2 2 ioxide (CO ), hydrogen chloride (HCl), and nitrogen dioxide (NO ). Speaking very generally, CO

alone accounts for half of the fire toxicity problem, although it is far less toxic than many of the other

gases found in fires. Nonetheless, CO is considered to be the primary toxicant because of its

copious generation by all fires. The importance of any toxic gas species to a particular fire must

reflect both its toxicity and its actual concentration in that particular fire. The time of exposure is

also important for determining the effects from toxic gases. In general, a higher concentration

allows the same biological effect to be reached in a shorter time. For toxicity data, the exposure

period normally used is 30 minutes.

The following definitions of toxicity related terms are commonly used in fire and combustion

toxicology, as defined by ASTM Standard E176-98:

• Toxic hazard is the potential for physiological harm from the toxic products of combustion.

Toxic hazard reflects both the quantity and quality of toxic products (quality is typically

expressed as toxic potency. Toxic hazard is not the only hazard associated with fire, and

is not an intrinsic characteristic of a material or product. Rather, toxic hazard depends upon

the fire scenario, the condition of use of the material or product, and possibly other factors.

• Toxic potency is a quantitative expression that relates concentration and exposure time

to a particular degree of adverse physiological effects (for example, death) on exposure of

humans or animals. The toxic potency of the smoke from any material, product, or

assembly is related to the composition of that smoke, which, in turn, depends upon the

conditions under which the smoke is generated. Toxic potency of the smoke from a

specimen or product is determined on a per-unit-specimen-mass basis. At present, for fire

research, the dominant biological end point adopted is death and the measured quantity is

50 the LC , which is the concentration (g/m ) of smoke which is lethal to 50-percent of the 3

exposed specified test animals in a specified time period. (The meaning of this variable is

the amount of mass that needs to be dispersed into a volume of 1 m in order to cause a

3

50-percent probability of lethality.) For substances where the composition is known (e.g.,

pu 50 rge gases), the LC is usually expressed in units of ppmv. The definition here is that 1

ppmv of gas means that there is one part of gas per million parts of air. The “v” denotes

par 50 ts by volume rather than weight. The LC notation must include the exposure time,

generally 30 minutes (along with a 14-day post-exposure observation period) (Babrauskas

et al., 1991). The toxic potency is not an intrinsic characteristic of a material.
B-67

B.17.2 Smoke and Toxic Gases

Many studies have been undertaken on toxic combustion products of organic materials, with the

object 2ive of realistically assessing the associated hazard. Toxicities of CO, CO , HCN, HCl, and

2

low O have been examined in depth by Babrauskas (1991), who determined that narcosis is

2 2 caused by fire gases, such as CO and HCN, as well as low O concentrations and high CO

concentrations. Narcotic gases cause incapacitation mainly by acting on the central nervous

system and, to some extent, the cardiovascular system. Most narcotic fire gases produce their

effects by causing brain tissue hypoxia. Since the body possesses powerful adaptive mechanisms

designed to maximize oxygen delivery to the brain, it is usually possible to maintain normal body

functions up to a certain concentration of a narcotic, and be unaware of the impending intoxication.

However, once the threshold is reached where normal functioning can no longer be maintained,

deterioration is rapid and severe, beginning with signs similar to the effects of alcohol intoxication,

including lethargy or euphoria with poor physical coordination, followed rapidly by unconsciousness

and death if exposure continues (Tamura, 1994).

The manual of the American Conference of Governmental Industrial Hygienists, Inc., gives the

threshold limit values (TLVs) and a description of various toxic gases. The TLV is defined as the

time-weighted average concentration for a normal 8-hour workday and a 40-hour workweek to

which nearly all workers may be repeatedly exposed, day after day without adverse effect. The

TLVs and biological effects of concentrations above the TLV for toxic gases are discussed in the

following subsections (Tamura, 1994).

B.17.2.1 Carbon Monoxide (CO)

CO is a common product of combustion generated in a fire environment. This highly toxic, nonirritating gas has long been recognized as a primary cause of fatalities related to combustion

sources including fire. In fact, the majority of all fire fatalities are attributed to CO inhalation. CO

is produced as a result of incomplete combustion of materials containing carbon and is present in

large quantities in most fires. Invisible, odorless, tasteless, and slightly lighter than air, CO is the

most significant toxicant as it can cause occupants to become incapacitated if the concentration

is high enough and the exposure is long enough. CO acts by combining with hemoglobin in the

blood to form carboxyhemoglobin (COHb). This is important because hemoglobin carries oxygen

throughout the body, and it cannot do this if it is tied up as COHb and, therefore, unavailable for

oxygen transport. In the absence of other contributing factors, a COHb concentration of 50-percent

or greater is generally considered lethal in the blood of fire victims.

The highest concentration of CO to which people can be exposed day after day without adverse

effect is 50 ppm. This concentration keeps the COHb level below 10-percent. Concentrations of

400 to 500 ppm can be inhaled for 1 hour without appreciable effect. Concentrations of 1,000 to

1,200 ppm cause unpleasant symptoms after 1 hour of exposure. Concentrations of 1,500 to 2,000

ppm for 1 hour of exposure are dangerous, and concentrations above 4,000 ppm are fatal in

exposure of less than 1 hour (Sumi and Tsuchiya, 1971).
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B.17.2.2 Hydrogen Cyanide (HCN)

HCN is one of the most rapidly acting toxicants, being approximately 20 times more toxic than CO.

HCN is produced when materials involved in a fire contain nitrogen [for example, polyacrylonitrile

(Orlon ), polyamide (nylon), wool, polyurethane, urea-formaldehyde, and acrylonitrile-butadiene- ®

styrene (ABS)]. Inhalation of HCN may cause severe toxic effects and death within a few minutes

up to several hours, depending upon the concentration inhaled. The action of HCN is attributable

to the cyanide ion, which is formed by hydrolysis in the blood. Unlike CO, which remains primarily

in the blood, the cyanide ion is distributed throughout the body fluids, bringing it into contact with

the cells of vital tissues and organs.

The TLV for HCN is 10 ppm, and it can be inhaled for several hours without appreciable effect at

concentrations of 20–40 ppm. The maximum amount that can be inhaled for 1 hour without serious

reaction is 50–60 ppm. Concentrations of 120–150 ppm are dangerous in 30–60 minutes, and

concentrations of 3,000 ppm or more are rapidly fatal (Sumi and Tsuchiya, 1971).

B.17 2.2.3 Carbon Dioxide (CO )

CO2 usually evolves in large quantities from fires. While not particularly toxic at observer levels,

moderate 2concentrations of CO (on the order of 2-percent) increase both the rate and depth of

breathing by about 50-percent, thereby increasing the respiratory minute volume (RMV). This

condition contributes to the overall hazard of a fire gas environment by causing accelerated

2

inhalation of toxicants and irritants. If 4-percent CO is breathed, the RMV is approximately

doubled, 2 but the individual may scarcely notice the effect. Given any further increase in CO from

4 percent up to 10-percent, the RMV may be 8 to 10 times the resting level (Hartzell, 1989).

The TLV of 2 CO is 5,000 ppm. Stimulation of respiration is pronounced at a concentration of 5-

percent (50,000 ppm), and a 30-minute exposure produces signs of intoxication. Above 70,000

ppm, unconsciousness results in a few minutes (Sumi and Tsuchiya, 1971).

B.17.2.4 Hydrogen Chloride (HCl)

HCl is formed from the combustion of materials containing chlorine, the most notable of which is

polyvinyl chloride (PVC) as used in common thermoplastic electrical cables. HCL is both a potent

sensory irritant and potent pulmonary irritant. It is a strong acid, being corrosive to sensitive tissue,

such as the eyes. If inhaled, HCl will irritate and damage the upper respiratory tract and lead to

asphyxiation or death.

The TLV for HCl is 5 ppm. Concentrations as low as 75 ppm are extremely irritating to the eyes and

upper respiratory tract, and behavioral impairment has been suggested. The maximum

concentration allowable for short exposures of 30–60 minutes is 50 ppm. Concentrations of

1,000–2,000 ppm are dangerous even for short exposures (Sumi and Tsuchiya, 1971).
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B.17.2.5 Nitrogen Dioxides

N 2 2 4itrogen dioxides (NO and N O ) are the common oxides of nitrogen (N) that are produced in a fire.

(The other is nitric oxide, or NO.) Nitrogen dioxide, which is very toxic, can be produced from the

combustion of N-containing material. Nitric oxide has a short life in atmospheric air because it is

converted into dioxide in the presence of oxygen. These compounds are strong irritants,

particularly to mucous membranes. When inhaled, they damage tissues in the respiratory tract by

reacting with moisture to produce nitrous and nitric acids. The TLV for nitrogen dioxide is 5 ppm.

Immediate throat irritation can begin at 62 ppm. Short-exposure concentrations of 117–154 ppm

are dangerous, and rapidly fatal at 140–775 ppm (Sumi and Tsuchiya, 1971).

B.17.3 Toxicity Data

Toxicity or toxic data usually reflect the results of animal testing. The table of relative acute toxicity

criteria given below was published by the National Institute for Occupational Safety and Health

(NIOSH) in the Registry of the Toxic Effects of Chemical Substances (RTECS) in 1967. It is widely

used to interpret animal toxicity data; the lower the dose number, the greater the toxicity. The

measu 50 50 res of toxicity used in the Table B.17-1, LD and LC are explained in the discussion

following the table (Spero, Devito, and Theodore, 2000).

Table B.17-1. Toxicity Data

Rat 50 ing Keywords LD Single Oral

Dose*

(mg/kg)

LC50 Inhalation

Vapor Exposure*

(ppm)

LD50 Skin**

(mg/kg)

4 Extremely hazardous #1 #10 #5

3 Highly hazardous 50 100 43

2 Moderately hazardous 500 1000 340

1 Slightly hazardous 5,000 10,000 2,800

0 No significant hazard >5,000 >10,000 >2,800

* Rats

**Rabbits
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Data on animal toxicity usually identify the route of entry into the body (oral ingestion, inhalation,

adsorption through the skin, etc.) first, followed by the test animal (mouse, rat, human, etc.),

followed by the measure of toxicity. The most common measures of toxicity are as follows:

50 • Lethal Dose 50-percent (LD ) is the dose required to kill 50-percent of the test animals

when administered by a route of entry other than inhalation. The dose of the chemical

(usually solids or liquids) is given as mg/kg, which represents milligrams of chemical per

50 kilogram of body weight of the test animal. The LD is expressed in this manner because

mo 50 re chemical is needed to kill a larger animal. For example, the oral rat LD for the HAP

calcium cyanamide is 159 mg/kg.

50 50 • Lethal Concentration 50-percent (LC ) is similar to LD except that the route of entry is

inhalation. The concentrations of the inhaled chemicals (usually gases) are expressed as

parts per million (ppm) or milligrams per cubic meter (mg/m ). 3

o

• Lethal Dose Low (LDL ) is the lowest dose required to kill any of the animals in the study

when administered by a route of entry other than inhalation.

o o • Lethal Concentration Low (LCL ) is the same as LDL except that the route of entry is

inhalation.

o

• Toxic Dose Low (TDL ) is the lowest dose used in the study that caused any toxic effect (not

just death) when administered by a route of entry other than inhalation.

o o • Toxic Concentration Low (TCL ) is the same as TDL except that the route of entry is

inhalation.

50 • EC is the concentration required to cause a 50-percent reduction in growth.

• Acute Risks are the risks associated with brief exposures to high concentrations.

• Chronic Risks are the risks associated with long-term exposures to low concentrations.
B-71

B.17.4 References

ASTM E176-98, “Standard Terminology of Fire Standards,” ASTM Fire Test Standard, 5 Edition, th

American Society of Testing and Materials, West Conshohocken, Pennsylvania, pp. 834–842,

1999.

Babrauskas, V., “Effective Measurement Techniques for Heat, Smoke, and Toxic Fire Gases,” Fire

Safety Journal, Volume 17, No. 1, pp. 13–26, 1991.

Babrauskas, V., B.C. Levin, R.G. Gann, M. Paabo, R.H. Harris, R.D. Peacock, and S. Yusa, “Toxic

Potency Measurement for Fire Hazard Analysis,” NIST Special Publication 827, U.S. Department

of Commerce, National Institute of Standards and Technology (NIST), Building and Fire Research

Laboratory (BFRL), Gaithersburg, Maryland, 1991.

Beitel, J.J., C.L. Beyler, L.A. McKenna, and F.W. Williams, “Overview of Smoke Toxicity Testing

and Regulations,” NRL/MR/6180-98-8128, Naval Research Laboratory, Naval Technology Center

for Safety and Survivability Branch, Chemistry Division, Washington, DC, April 15, 1998.

Clarke, Frederick B. “Toxicity of Combustion Products: Current Knowledge,” Fire Journal, 77, 5

(September 1983), 84-97, 101, 108.

Hartzell, G.E., “Understanding of Hazards to Humans,” Chapter 3, Advances in Combustion

Toxicology, Volume One, Gordon, E. Hartzell, Editor, Technomic Publishing, Inc., 1989.

Spero, J.M., B. Devito, and L. Theodore, Regulatory Chemicals Handbook, Marcel Dekker, Inc.,

New York, 2000.

Sumi, K., and Y. Tsuchiya, “Toxic Gases and Vapors Produced at Fires,” Canadian Building Digest,

National Research Council of Canada, CBD 144, December 1971.

Tamura, G.T., Smoke Movement & Control, National Fire Protection Association, Quincy,

Massachusetts, December 1994.
B-72

B.18 Effects of Decomposition Products of Halogenated Fire Extinguishing Agents

B.18.1 Introduction

When an ineffective Halon fire extinguishing system that is incapable of extinguishing its designbasis fire is installed in a compartment, the system discharge will actually degrade environmental

conditions by introducing additional toxic gases.

The 18 Edition of the National Fire Protection Association (NFPA) Fire Protection Handbook th

(Taylor, 1997) identifies the effects of the decomposition products of Halon 1301 and 1211 fire

extinguishing agents, as follows:

Consideration of life safety during the use of halogenated agents must also include the

effects of decomposition (or breakdown) products, which are relatively more toxic to

humans. Decomposition of halogenated agents takes place on exposure to flame or

surface temperatures above approximately 482 °C (900 °F). In the presence of available

hydrogen (from water vapor or the combustion process itself), the main decomposition

products of Halon 1301 are hydrogen fluoride (HF), hydrogen bromide (HBr), and free

brom 2 2 2ine (Br ). Although small amounts of carbonyl halides (COF , COBr ) were reported

in the early tests, more recent studies have failed to confirm the presence of these

compounds.

Table B.18.1-1 summarizes the major decomposition products of Halon 1301 and 1211. The

approximate lethal concentrations (ALCs) for a 15-minute exposure to some of these compounds

are given in Column 2 of Table B.18-1. Column 3 gives the concentrations of these materials that

have been quoted as “dangerous” for short exposure.

Even in minute concentrations of only a few parts per millions (ppm), the decomposition products

of the halogenated agents have a characteristically sharp, acrid odor. This characteristic provides

a built-in warning system for the agent, but also creates a noxious, irritating atmosphere for those

who must enter the hazard area following a fire. It also serves as a warning that other potentially

toxic products of combustion (such as CO) will be present.
B-73

B.18.2 Toxicity of Decomposition Products of Halogenated Fire Suppression Agents

Hill (1977) summarizes the effects of hydrogen fluoride (HF) on humans at various concentrations.

At concentrations as low as 32 ppm, irritation of eyes and nose occurs. At 60 ppm, irritation of the

respiratory tract occurs after 60 seconds. At concentrations of 120 ppm, irritation of the conjunctival

and respiratory tracts is tolerable for only 60 seconds. Concentrations between 50 and 100 ppm

are considered dangerous to life after several minutes of exposure. Generally, the HF containing

atmospheres are so irritating that personnel will be forced to evacuate before serious health risk

is incurred. Decomposition product data clearly indicate that life-threatening concentrations of HF

likely. HF concentrations of 300 ppm are typically measured in full-scale tests.

Table B.18-1. Approximate Lethal Concentrations (ALCs)

for Predominant Halon 1301 and Halon 1211 Decomposition Products

Compound ALC for 15-minute Exposure

(ppm by Volume in Air)

Dangerous Concentrations

(ppm by Volume in Air)

Hydrogen fluoride, HF 2,500 50–250

Hydrogen bromide, HBr 4,752 -

Hydrogen chloride, HCl - -

B 2romine, Br 550 -

Chlor 2ine, Cl - 50

Carbony 2l fluoride, COF 1,500 -

Carbony 2l chloride, COCl 100–150 -

Ca 2rbonyl bromide, COBr - -
B-74

DeMonburn and McCormick (1973) have reported on the design and testing of Halon 1301 in

extinguishing a wool bag filter fire in an industrial baghouse situation. The baghouse studied has

an area of approximately 13.3 m (144 ft ). These studies indicate that using rate-of-rise thermal 2 2

detectors and the complete shutdown of the air flow through the baghouse, a 4-percent

concentration of Halon 1301 would extinguish a fully developed fire. However, it should be noted

that following extinguishment and 20 minutes soaking time, toxic levels of hydrogen fluoride,

hydrogen cyanide, and hydrogen sulfide were detected in the unoccupied baghouse as shown in

Table B.18-2.

Table B.18-2. Concentration of Hazardous Gases Attributable to 

Decomposition of Halon 1301 in Industrial Baghouse Fire Situation

Time

(minutes)

Decomposition Product Concentration

(ppm)

Hydrogen Fluo 2ride (HF) Hydrogen Cyanide (HCN) Hydrogen Sulfide (H S)

0–4 55 1,643 2,452

20–24 10 194 112

The National Research Council Advisory Center reviewed the toxicity of Halon 1301

for consideration by NASA. In a letter to Dr. G.J. Stopps of the Haskell Laboratory, dated

September 22, 1967, R.C. Wands, Director of the Toxicology Center, stated:

Personnel can be exposed without significant hazard for a maximum of 5 minutes

to normal air at 1 atmosphere and mixed with up to 6-percent mean concentration

by 3volume of bromotrifluoromethane [CF Br (Halon 1301)] as a fire extinguishing

agent. This assumes appropriate engineering design to sense the fire and deliver

the agent so as to extinguish the fire promptly in order to minimize that pyrolysis

products (Atomic Energy Commission, 1970).
B-75

Ford (1975) has evaluated the issue of the decomposition of Halon 1301, and believes caution and

limitations should be applied to the utilization of extinguishing systems containing that agent:

• Although safe at a design concentration of 5–7-percent, the Halon 1301 agent will not

extinguish deep-seated Class A fires with these concentrations. Thus, water systems

should be provided and higher concentrations of Halon 1301 should be used for

extinguishment in these situations. If higher concentrations of Halon 1301 are provided, the

design of the system should incorporate all of the requirements of the NFPA Standard 12A,

and the operation of the system in relation to the personnel hazard should be identical to

2

that of a CO extinguishing system.

• Halon 1301 may decompose to untenable concentrations of hydrogen fluoride and

hydrogen bromide when the vapor is in contact with a heated surface above 482 °C

(900 °F), or when the agent is applied to a large fire in a small enclosure. Table B.18-3

summarizes the relationship between the flame shield exposure and room size. Note in

Situation One that the ratio of flame dimension to room size is 0.60, while in Situation Two,

the ratio of flame dimension to room size is 6.0. The concentrations of the hydrogen

fluoride and hydrogen bromide acid gases in situation two are beyond tolerable limits for

human exposure. However, it must be remembered in this situation and the previous

industrial baghouse situation presented by DeMonburn and McMormick, that the toxic

products of combustion from the fire would in all probability also create an intolerable

atmosphere for human exposure. The primary life hazard involves the entry of personnel

into the area immediately following extinguishment. These characteristics of the Halon

agent under intense thermal or flame exposure make the installation of these systems for

an oven or furnace chamber unsuitable where the temperature is above 260 °C (500 °F).

B.18.3 Physical Properties of Halon 1301

Under normal conditions, Halon 1301 is a colorless, odorless gas with a density approximately 5

times that of air. It can be liquefied upon compression for convenient shipping and storage. Unlike

CO2, Halon 1301 cannot be solidified at temperatures above -167.8 °C (-270 °F). The molecular

weight of Halon 1301 is 148.93 (see Table B.18-4).
B-76

B.18.4 Physical Properties of Halon 1211

Under normal conditions, Halon 1211 is a colorless gas with a faintly sweet smell and a density

about 5 times that of air. It can be readily liquefied by compression for storage in closed vessels.

The molecular weight of Halon 1211 is 165.38 (see Table B.18-4 for properties of Halon).

Table B.18-3. Halon 1301 Decomposition Produced by n-Heptane Fires

Situation One: 1,695-foot Enclosure Volume; 4-Percent Halon 1301 by Volume

Fire pan size

(ft )

2

Fuel area to

volume

ft /1000 ft 2 2

Discharge

time

(sec)

Extinguishment time

(sec)

Decomposition products

(ppm volume in air)

Hydrogen

Fluoride

(HF)

Hydrogen

Bromide

(HBr)

0.1 0.06 23.0 11.5 1.8 3.5

0.1 0.06 13.5 7.1 1.8 2.1

0.1 0.06 5.7 4.8 1.4 2.8

Situation Two: 1,695-foot Enclosure Volume; 4-Percent Halon 1301 by Volume

Fire pan size

(ft )

2

Fuel area to

volume

ft /1000 ft 2 2

Discharge

time

(sec)

Extinguishment time

(sec)

Decomposition products

(ppm volume in air)

Hydrogen

Fluoride

(HF)

Hydrogen

Bromide

(HBr)

10.0 6.0 25.0 20.0 1,907 397

10.0 6.0 15.0 16.3 1,206 382

10.0 6.0 6.0 10.0 666 112

10.0 6.0 6.0 5.2 320 38

Table B.18-4. Selected Properties of Halon 1301, 1211, and 2402

Extinguishing Agent Halon 1301

3

(CF Br)

Halon 1211

2

(CF ClBr)

Halon 2402

2 4 2

(CFBr )

Boiling point °C (°F) -58 (-72.5 °F) -4 (25 °F) 47 (117 °F)

Liquid density at 20 °C (g/cc) 1.57 1.83 2.17

Latent heat of vaporization (J/g) 117 134 105

Vapor pressure at 20 °C (atm) 14.5 2.5 0.46
B-77

B.18.5 References

Atomic Energy Commission, “Prepackaged Halon 1301 Fire Suppression System Tests,” Number

294, Atomic Energy Commission, Health and Safety Information, Washington, DC, 1970.

DeMonburn, J.R., and J.W. McCormick, “Extinguishment of Wool Bag Filter Fires Using Halon

1301,” Y-JA-94, Union Carbide Corporation, 1973.

Ford, C.B., “Why Not Halon1301?” Fire Journal, Volume 69, pp. 80–81, 1975.

Hill, R., “Evaluation of Halon 1301 System for Aircraft Internal Protection from a Postcrash External

Fuel Fire,” National Aviation Facilities Experimental Center, Atlantic City, New Jersey, March 1977.

Taylor, G.M., Halogenated Agent and Systems, Chapter 18, Section 6, NFPA Fire Protection

Handbook, 18 Edition, Edition, A.E. Cote, Editors-in-Chief, National Fire Protection Association, th

Quincy, Massachusetts, 1997.
B-78

B.19 An Introduction to Computer Fire Models

B.19.1 Introduction

ASTM E176 defines a fire model as a physical or mathematical representation of burning or other

processes associated with fire. Physical models attempt to reproduce fire phenomena in a

simplified physical situation. For example, scale models are a very widespread form of modeling,

as full-scale experiments are expensive, difficult, and sometimes wholly infeasible. Insight can

often be gained by studying fire phenomena at a reduced physical scale. Mathematical fire models

include one or more empirical equation(s) that can be solved analytically or a set of complex

differential and algebraic equations that must be solved numerically on a computer. A computer

program to accomplish the numerical solution of complex set of differential and algebraic equations

is called a computer fire model. Fire modeling can normally be considered as the prediction of fire

characteristics by the use of a mathematical method which is expressed as a computer program.

The computer fire models have invaluable tools to assist in a wide range of uses in fire protection

engineering research and development, fire-safe design of a structure, fire hazard analyses, fire

spread, smoke control systems design, structural response of building members, human behavior

and egress in the event of fire, actuation of thermal devices (sprinklers, detectors, ceiling vents

etc.), hydraulic design of fire suppression systems, and fire investigation and reconstruction. Many

building and fire regulations (including NFPA 805, “Performance-Based Standard for Fire Protection

for Light Water Reactor Electric Generating Plants”) allow for use of computer fire modeling as part

of the performance-based fire safety designs to help bridge the gap between building functionality

and fire code. The performance-based fire safety engineering is defined as “an engineering

approach to fire protection design based on (1) agreed fire safety goals, loss objectives, and design

objectives; (2) deterministic and probabilistic evaluation of fire initiation, growth, and development;

(3) the physical and chemical properties of fire and fire effluents; and (4) quantitative assessment

of the effectiveness of design alternatives against loss objectives and performance objectives”

(Meacham and Custer, 1995 and Custer and Meacham, 1997).
B-79

B.19.2 Categories of Computer Fire Model

Fire models can be grouped into two categories: probabilistic or stochastic fire model and

deterministic fire models. Probabilistic fire models involve the evaluation of the probability of risk

due to fire based on the probabilities of all parameters influencing the fire such as human behavior,

formation of openings and distribution of fuel load in the compartment of fire origin. The results of

the models are in terms of the statistical likelihood of the occurrences of fires and fire outcomes,

based on the random nature of fire and the likelihood of occurrence. Little or no information is given

with respect to production and distribution of combustion products. In contrast to the probabilistic

fire models, deterministic fire models are based on physical, chemical and thermodynamic

relationship and empirical correlation to calculate the impact of fire. Deterministic fire models can

be very simple requiring a short computing time or highly complex requiring hours of computation.

Typically deterministic fire models can be classified as zone models, field models, and other

models. The most commonly used computer fire models simulate the consequences of a fire in an

enclosure are zone and field models. Other models are special purpose models such as building

evacuation (egress) models, models of thermal actuation devices (sprinklers and detection

systems), models of structural fire resistance/endurance, fire sprinkler hydraulic design models,

smoke movement/migration models, and fire-sprinkler interaction models.

A large number of fire computer models have been developed in recent years indicating the interest

of researchers in the computer fire modeling field. A complete listing of these fire models is

available in the fire model survey Web site, www.firemodelsurvey.com. This Web site contains

information about the latest survey of computer fire models as completed by the developers of

these models.

B.19.2.1 Zone Models

A zone model is essentially a one-dimensional model that solves the basic conservation equation

for distinct volumes as a function of time. This type of model is used to predict fire growth and

smoke spread in single or multi-enclosure structures. The model calculates the temperature and

concentration of gas species (oxygen, carbon dioxide, etc.) as a function of time throughout the

spaces modeled.

Zone model usually divide each room into two spaces or zones; an upper hot zone that contains

the gases produced by the fire and a lower cool zone that is the source of the air for combustion.

Zone sizes change during the course of the fire. The upper zone can expand and occupy virtually

the entire room volume. By definition, zone models will always be approximate. The primary

advantage of a zone model is its relative simplicity, which permits the inclusion of more

phenomena. Also, cases may be run more rapidly and inexpensively on a personal computer.
B-80

A zone model requires input of the basic geometry of the space(s) being modeled, including

physical dimensions, thermal properties of bounding materials, vent opening sizes and locations,

mechanical ventilation, and position and growth rates of the specified fire. Output includes the

upper and lower smoke layer temperature, interface location between zones (smoke layer height),

oxygen and carbon monoxide concentrations, visibility, smoke flow in and out of openings, and heat

flux from the hot gas layer to a target in the compartment as a function of time. Some examples

of zone models are CFAST, FASTlite, ASET, COMPBRN-III, BRI-2, MAGIC, BRANZFIRE, FIGROII, FIREWIND, and FLAMME-S.

B.19.2.2 Field Models

Field models avoid the simplifications inherent in zone models and, consequently, their results are

very refined compared to those of a zone fire model. Some field model calculations can be made

on fast PCs; however, more complex problems are best run on powerful workstations and advanced

computers. Such models numerically solve the conservation of mass, energy, and momentum, as

well as diffusion and species equations associated with fire. The temperature, velocity, and gas

concentration are calculated in two- or three-dimensional fields by using a finite difference, finite

element, or boundary element method. A compartment or space (domain) is descretized into

computational cells. The greater the number of cells, the more refined the solution. The model

determines the temperature, pressure, velocity, and species concentration within each cell at each

time step.

The advantage of field models over zone models is that they can provide detailed information on

fluid motions. The application of field modeling to fire problems has been dramatically increased

over time. The ready availability of commercial computational fluid dynamics (CFD) software

packages with increasing sophistication enable more widespread application. Applications of field

models to fire problems include aircraft terminal atria spaces, air-supported structures, electrical

generating stations, aircraft cabins, tunnels, hospitals wards, shopping malls, and warehouses.

Some examples of field models are FDS, FLUENT, STAR-CD, JASMINE, PHOENICS, KOBRA-3D,

FIRE, VESTA, and SOFIE.

B.19.2.3 Building Evacuation Model

Egress models are not truly fire models. They were developed in response to the need to evaluate

the impact of fires on the occupants of a building. Most egress models describe the building as a

network of paths along which the occupants travel. The occupants travel rates are usually derived

from studies on people movement and vary with the age and ability of the occupants, crowding, and

the types of travel paths. Model inputs include the geometry of the building and rooms, the

openings between rooms, the number of occupants located each floor throughout the building, and

the smoke data if the effect of smoke blockage is to be considered. The outputs include the

location of each occupant with time, floor clearing time, stairwell clearing time, exit clearing time,

and how many occupants used an exit. Some examples of evacuation models are EVACNET,

EVACS, EGRASS, EXIT89, buildingEXODUS, BFIRII, Allsafe, EgressPro, and EESCAPE.
B-81

B.19.2.4 Models of Thermal Actuation Devices

Sprinkler and detection activation models are used to calculate the response time of sprinklers and

detectors installed below unconfined smooth ceilings. These models also are used to estimate the

size of a fire when a detection system activates, at which point egress can begin. Sprinkler and

detection activation models use a heat transfer equation to calculate the temperature increase of

detector sensing elements. These models assume that the thermal devices are located in a

relatively large area and are heated by the ceiling jet flows (convective heat transfer), and predict

the device actuation time for a user-specified heat release rate history. The sensitivity of the

sprinkler/detector sensing element to an elevated temperature is often characterized by a constant

parameter known as the response time index (RTI) which is derived experimentally. The required

model inputs are the height of the ceiling above the fuel, distance of the thermal device from the

axis of the fire, actuation temperature of the thermal device, RTI for the device, and heat release

rate of the fire. The model outputs are the ceiling gas temperature at the device location and the

device temperature (both as a function of time), time required for the device to actuate, and heat

release rate at actuation. Some examples of thermal actuation modeled are DETACT-QS,

DETACT-T2, LAVENT, JET, G-JET, and SPRINK.

B.19.2.5 Models of Structural Fire Resistance/Endurance

Structural fire resistance models estimate the structural fire endurance of a building system or

member exposed to a fire environment by numerically solving the conservation of energy equations

using a finite difference or finite element technique. The solution techniques are very similar to

those used with field models. The structural fire resistance models evaluate the time-temperature

history within a solid exposed to a fire environment. The solid region is divided into elements in

much the same way that the field models divide a compartment into regions.

Steel and concrete configurations are most commonly analyzed with and without fire protection

insulation. The models allow nonlinear material properties and boundary conditions. An effective

analysis makes use of a mesh that finds where there are large temperature gradients. The thermal

properties that are necessary to perform such an analysis are the thermal conductivity and specific

heat. The density is also required, as are phase change (intumescent) data. The time-temperature

history of the fire environment is considered by specifically defining the temperature at each time

step during the solution. The heat transfer process attributable to the fire exposure is modeled

using convection and/or radiation in the fire boundary and conduction through the solid. Some

examples of PC-based structural fire resistance models are FIRES-T3, HEATING 7, FASBUS,

TASEF, FIRES-RC ΙΙ, and SAFIR.
B-82

B.19.2.6 Fire Sprinkler Hydraulic Design Models

Fire sprinkler hydraulic design models are used to perform all necessary calculations to design a

sprinkler system with a grid or loop, as required by NFPA 13, “Standard for Installation of Sprinkler

Systems,” to ensure that water supplies will meet the water density requirements for the control and

extinguishment of fire. These models estimate sprinkler head requirements, water supply pressure,

the lowest supply pressure that can adequately drive the sprinkler system, pipe sizes, and

equivalent lengths for fittings. These models use conservation of mass and momentum equations

based on the principles of hydraulic (fluid) motion. The fire sprinkler models work by dividing a

sprinkler system network into a series of nodes and links. The nodes represent pipe junctions of

sprinklers, while links represent pipes. The user can specify which sprinklers are open and the

model balance the flow and pressure. The inputs to the model are pipe junctions, diameters, and

length; the locations and types of fittings; and the sprinkler locations. Some examples of fire

sprinkler hydraulic design models are FIRE, HCALC, HP4M-Grid Fire Sprinkler Design, HP6M-Tree

and Loop Fire Sprinkler Design, THE, HASS, HyperCalc, and Sprinkler-CALC.

B.19.2.7 Smoke Movement Models

Smoke movement/migration models calculate the airflow and pressure differences throughout a

building in which a smoke control system is operating in a fire situation. In these modes, a building

is represented as a network of spaces or nodes, each at a specific pressure and temperature. The

stairwells and other shafts are modeled by a vertical series of spaces, one for each floor. The air

flow is a function of pressure differences across the leakage paths. That is, air flows through

leakage paths from regions of high pressure to regions of low pressure. These leakage paths are

doors and windows that may be opened or closed. Leakage can also occur through partitions,

floors, and exterior walls and roofs. The model inputs include the interior and exterior building

temperatures, a description of the building flow network, and the flow produced by the ventilation

or smoke control system. The outputs include the steady-state pressure and flows throughout the

building. These models are capable of modeling the stack effect created in taller buildings during

extreme temperature conditions. Some examples of smoke movement/migration models are

ASCOS, CONTAMW, AIRNET, and ASMET.
B-83

B.19.2.8 Fire-Sprinkler Interaction Models

Fire-sprinkler interaction models simulate the environment and the response of sprinkler actuation

links in compartment fires with draft curtains and fusible link-operated ceiling vents. They include

the effects of the ceiling jet and upper layer of hot gases beneath the ceiling. The program inputs

include the compartment geometry, thermo-physical properties of the ceiling, fire elevation, fire heat

release rate, fire diameter, ceiling vent area, fusible link RTI and actuation temperature, fusible link

positions along the ceiling, link assignment to each ceiling vent, and ambient temperature. The

model outputs include the temperature, mass, and height of the upper layer; temperature of each

link; ceiling jet temperature and velocity at each link; radial temperature distribution along the

interior surface of the ceiling; radial distribution of heat flux to the interior and exterior surfaces of

the ceiling; fuse time of each link; and vent area that has been open. Examples of fire-sprinkler

interaction models include LAVENT and JET.

B.19.2.9 Specialized Fire Models

Special-purpose fire simulation programs include (1) BREAK1 (Berkeley Algorithm for Window

Glass in a Compartment Fire), a program which calculates the temperature history of a glass

window exposed to user-described fire conditions, and (2) ELVAC (Elevator Evacuation), an

interactive computer program that estimates the time required to evacuate people from a building

with the use of elevators and stairs. It is cautioned that elevators generally are not intended as a

means of fire evacuation, and they should not be used during fires except when under fire service

operation and control. However, it is possible to design elevator systems that for fire emergencies,

and ELVAC can be used to evaluate the potential performance of such a system. A third specialpurpose fire simulation program, known as FIRDEMND, simulates the suppression of post-flashover

charring and non-charring solid-fuel fire in compartments using water sprays from portable hosenozzle equipment used by the fire department.

The output of the Fire Demand Model (FDM) shows the extinguishment effects of water spray at

various flow rates and droplet sizes. The Subway Environment Simulation(SES ) computer program

and subway environmental design handbook were developed in the early 1970s under sponsorship

of the Urban Mass Transportation Administration (former name of the Federal Transit Administration

(FTA)) to assist in the planning, design, and construction of subway ventilation systems. The SES

fulfilled an unmet need in the transit engineering community, and has been widely used in the

design of new rail systems or line extensions in Washington, DC, Atlanta, Buffalo, Baltimore, Dallas,

Los Angeles, San Francisco, Montreal, Toronto, the Seattle Bus Tunnel, and rail transit systems

around the world. The SES provides tunnel designers with the tools to: properly size and locate

ventilation shafts, evaluate tunnel geometry and fan size, optimize temperature, and model the

effects of heat and smoke resulting from fires and other sources. The most recent enhancement

is the validation of the subroutine which describes the behavior of smoke in emergency conditions.
B-84

B.19.3 Limitations and Uncertainties Associated with Computer Fire Modeling

Fire model permit development of a better understanding of the dynamics of building fires, to

quantify the performance of a building, and can aid in the fire safety decision making process. This

evaluation gives an overall fire assessment of the building systems in terms of preventing fire

growth, providing for safe evacuation, providing for fire-resistance design, and predicting occupant

behavior.

Nonetheless, there are certain limitations and uncertainties associated with fire modeling

predictions. The decision to use a particular fire model should be based on the understanding of

the limitations and assumptions of the model. The limits of applicability of any fire model must be

clearly stated and known to the user so that the user does not go beyond the boundaries of realistic

application of the theory utilized. The input uncertainty is primarily attributable to error and

assumptions in the input data. Sensitivity analyses are used to identify the critical input parameters,

which must be specified with much greater care than the parameters to which the model is relatively

insensitive. The model uncertainty is primarily attributable to the assumptions made by the model,

and can be quantified as a result of the validation process. Full-scale fire test data are subject to

experimental uncertainty. Therefore, discrepancies between model predictions and experimental

data might be at least partly, attributable to measurement errors. There are many problems in

comparing the results from fire model simulations to data from full-scale experiments. Some of the

problems are attributable to the difference between the form of the recorded experimental data and

the form needed for computer model predictions. For example, contrary to the assumption of preflashover compartment zone models, there often is not a clear and sharp change distinguishing the

lower and upper gas layers.

Extreme care must be exercised in interpreting the fire modeling results. For scenarios where the

level of predicted hazard is well below the damage threshold, the results can be used with a high

level of confidence, provided that there is a high level of confidence that all risk-significant scenarios

have been considered. For scenarios where the level of predicted hazard is near the damage

threshold, the results should be used with caution in view of the inherent uncertainties.

A primary method of handling modeling uncertainties is the use of engineering judgment. Among

other things, this judgment is reflected in the selection of appropriate fire scenarios, hazard criteria,

and fire modeling techniques. A slightly more formal application of engineering judgment is the use

of safety factors, which can be applied in the form of fire size, increased or decreased fire growth

rate, or conservative hazard criteria (Custer and Meacham, 1997). Experimental data obtained

from fire tests, statistical data from actual fire experience, and other expert judgment can also be

used to improve judgment and potentially decrease the level of uncertainty.

When using a fire model, it is wise to perform a sensitivity analysis of the output to changes in the

input to determine if changes in the data or the model assumptions and applicability will lead to a

different decision. The sensitivity analysis will determine the most dominant and significant

variables. It will also determine whether the user should pay careful attention to particular input

values that might affect the result significantly.
B-85

B.19.4 Fire Models

A variety of computer fire models employing different features are currently available. Table B.19-1

provides a short description for some common fire models.

Table B.19-1. Computer Fire Models

Model Name Classification Model Use

CFAST

Consolidated Model of Fire

Growth and Smoke Transport

Zone model CFAST is a zone model that predicts the effect of

a specified fire on temperatures, various gas

concentrations and smoke layer heights in a multicompartment structure. 

FPETool

Fire Protection Engineering

Tool

Zone model FPETool is a set of engineering equations useful

in estimating potential fire hazard and the

response of the space and fire protection systems

to the developing hazard. Version 3.2 incorporates

an estimate of smoke conditions developing within

a room receiving steady-state smoke leakage

from an adjacent space. Estimates of human

viability resulting from exposure to developing

conditions within the room are calculated based

upon the smoke temperature and toxicity. 

FASTLite Zone model FASTLite is a user-friendly software package

which builds on the core routines of FPEtool and

the computer model CFAST to provide

calculations of fire phenomena for use by the

building designer, code official, fire protection

engineer, and fire-safety related practitioner.

ASET, ASET-B, ASET-C

Available Safe Egress Time

Zone model A simple, user-friendly, one-room, smoke-filling

model computer code that simulates the smoke

layer thickness, temperature, and concentrations

of products of combustion attributable to fire of

time-dependent, user-specified energy and

product release rate.

BRANZFIRE Zone model A zone model to predict the environment in a

compartmented structure.

COMPBRAN III Zone model Zone model for compartment fires, compatible

with probabilistic analysis.

MAGIC Zone model Two zone mode, able to handle up to 24

compartments. MAGIC is designed for nuclear

power plants. MAGIC is being extended to include

non-rectangular room, convex and sloping ceiling,

room cluttered with objects, spread of fire through

ventilation ducts, and extinction.
Table B.19-1. Computer Fire Models

Model Name Classification Model Use

B-86

FireWind Zone model FireWind is a collection of 18 programs that

include one- and two-room zone models, heat

radiation calculation, egress calculations, a heat

conductivity model and more. 

FIGARO II

Fire and Gas Spread in Room

Zone model FIGARO II is a two-layer model that can be used

for single-room and multi-room fire simulation.

FDS

Fire Dynamics Simulator

CFD model General-purpose, low-Mac number CFD code

specific to fire-related flows.

Star-CD CFD model General-purpose CFD code that contains industry

standard models for modeling fire and smoke

movement.

JASMINE

Analysis of Smoke Movement

in Enclosures

CFD model A CFD or field model for predicting consequences

of fire to evaluate design issues as the

assessment of smoke ventilation design and/or

interaction with HVAC and other fire protection

measures.

PHOENICS CFD model PHONICS is a general purpose CFD code for use

by academia and industry as a design and

analysis tool for any process involving fluid flow,

combustion, and heat and mass transfer.

SOFIE

Simulation of Fire in Enclosures

CFD model SOFIE is a field modeling code based upon the

solution of the Reynolds average Navier-Stokes

equations using a finite volume approach.

KOBRA-3D CFD model Three-dimensional CFD model for complex

geometries to be used for smoke spread and heat

transfer analyses.

FIRE CFD model CFD model with water sprays and coupled to

solid/liquid phase fuel to predict burning rate and

extinguishment.

DETACT-QS

DETector ACTuation-Quasi

Steady

Detector

actuation

A program for calculating the actuation time of

thermal devices below unconfined ceilings for fires

with arbitrary heat release rates.

DETACT-T2

DETector ACTuation-Time

Squared

Detector

actuation

A program for calculating the actuation time of

thermal devices below unconfined ceilings for fires

with heat release rates which grow with time

squared.
Table B.19-1. Computer Fire Models

Model Name Classification Model Use

B-87

LAVENT

Link Actuation VENTs

Zone model A zone model which predicts the actuation of

fusible links as a function of depth below the

ceiling and distance from the plume center in

response to a ceiling jet produced by a userspecified fire.

JET Zone model JET is a single compartment zone model for use

in spaces where the lower layer remains close to

ambient temperature and the fire is not ventilation

limited. The model provides temperature

predictions for the plume, ceiling jet, upper layer

and ceiling as well as the upper layer depth.

G-JET Smoke

detection

model

Design tool for all categories of smoke detectors

to predict their response to performance

requirements in applications.

EVACNET4 Evacuation/

egress model

EVACNET4 is a user-friendly interactive computer

program that models building evacuations. The

program accepts a network description and

information on its initial contents at the beginning

of the evacuation. 

ELVAC Elevator

evacuation

Calculates emergency evacuation time using

elevators.

EGRESS Evacuation

simulation

model

Versatile model for predicting the evacuation of

crowds which may be used in a large variety of

situations.

EXIT89 Evacuation

model

An evacuation model designed to handle the

evacuation of a large population of individuals

from a high-rise building.

buildingEXODUS Human

behavior/

evacuation

model

A PC-based evacuation model that simulates

individual people, behavior, and enclosure details. 

The model includes various aspects and is

capable of simulating thousands of people in large

geometries. 

FIRES-T3

FIre REsponse of Structures -

Thermal Three-Dimensional

Version

Finite element

method (FEM)

heat transfer

FEM conduction heat transfer with time-varying

boundary conditions and temperature-dependent

material properties for concrete structure frame.

FIRES-RC ΙΙ

Structural Analysis Program for

the Fire Response of

Reinforced Concrete Frame

Finite element

heat transfer

FEM for 1-, 2- or 3-D conduction heat transfer with

time-varying boundary conditions and

temperature-dependent material properties.
Table B.19-1. Computer Fire Models

Model Name Classification Model Use

B-88

TASEF

Temperature Analysis of

Structures Exposed to Fire

Structural TASEF is a computer program for temperature of

structures exposed to fire. This program is based

on the finite element method. It is developed for

temperature analysis of two dimensional and

axisymmetrical structures.

SAFIR

A Computer Program for

Analysis of Structures at

Elevated Temperature

Conditions

Structural

model

Transient analysis of the temperature distribution

in the structure; 2D or 3D, Steel, concrete,

gypsum and insulating material models; Eurocode

models; water evaporation; radiation in internal

cavities (2D).

Mechanical analysis of the structure during the

fire; 2D and 3D, beam, truss and shell F.E.; large

displacements; any cross-section type for the

beams, concrete, and steel eurocode models.

HEATING Structural

model

ASCOS

Analysis of Smoke COntrol

Systems

Network air

flow analysis

ASCOS is a program for steady air flow analysis

of smoke control system

CONTAMW

Multizone Airflow and

Contaminant Transport

Analysis Software

Airflow model CONTAMW is a multizone indoor air quality and

ventilation analysis program that is useful in a

variety of applications. For smoke management

purposes, the program can be used to help

calculate room-to-room airflow and pressure

differences induced by mechanical and natural

forces. 

ASMET

Atria Smoke Management

Engineering Tools

Package of

engineering

tools

ASMET consists of a set of equations and a zone

fire model for analysis of smoke management

systems for large spaces such as atria, shopping

malls, arcades, sports arenas, exhibition halls and

airplane hangers

BREAK1

Berkeley Algorithm for Breaking

Window Glass in a

Compartment Fire

BREAK1 is a program which calculates the

temperature history of a glass window exposed to

user-described fire conditions. The calculations

are stopped when the glass breaks.
B-89

B.19.5 References

ASTM E176, “Standard Terminology of Fire Standards,” ASTM Fire Test Standard, 5 Edition, th

American Society of Testing and Materials, West Conshohocken, Pennsylvania, 1999.

Custer, R.L., and B.J. Meacham, Introduction to Performance-Based Fire Safety, “Uncertainty and

Safety Factors,” Chapter 9, Society of Fire Protection Engineers (SFPE) and National Fire

Protection Association (NFPA), Quincy, Massachusetts, 1997.

“Information about Computer Models for Fire Growth and Smoke Transport,” available at Fire Model

Survey Web Site, www.firemodelsurvey.com. This Web site contains information about the latest

survey of computer fire models, as completed by the developers of those models.

Meacham, B.J., and R.L.P. Custer, “Performance-Based Fire Safety Engineering: An Introduction

of Basic Concepts,” SFPE Journal of Fire Protection Eng., Volume 7, No. 2. pp. 35–54: 1995.

B.19.6 Additional Readings

ASTM E1355-97, “Standard Guide for Evaluating the Predictive Capability of Deterministic Fire

Models,” ASTM Fire Test Standard, 5 Edition, American Society of Testing and Materials, West th

Conshohocken, Pennsylvania, pp. 1115–1120, 1999.

ASTM E1472, “Standard Guide for Documenting Computer Software for Fire Models,” ASTM Fire

Test Standard, 5 Edition, American Society of Testing and Materials, West Conshohocken, th

Pennsylvania, 1999.

Friedman, R., “An International Survey of Computer Models for Fire and Smoke,” SFPE Journal of

Fire Protection Engineering, Volume 4, No. 3. pp. 81–92, November 1992.

Hunt, S.P., “Computer Fire Models,” NFPA Update, Issue 839, p. 7, October/November 2000.

Janssens, M.L., “Evaluating Computer Fire Models,” Fire Protection Engineering Magazine, Society

of Fire Protection Engineers, Bethesda, Maryland, pp. 19–22, Winter 2002.

Janssens M.L., and D.B. Birk, An Introduction to Mathematical Fire Modeling, 2 Edition, nd

Technomic Publishing Company, Lancaster, Pennsylvania, 2000.

Mehaffey, J.R., Mathematical Modeling of Fire, ASTM Special Technical Publication, STP 983,

American Society for Testing & Materials, Philadelphia, Pennsylvania, January 1988.

Olenick, S.M., and D.J. Carpenter, “An Updated International Survey of Computer Models for Fire

and Smoke,” SFPE Journal of Fire Protection Eng., Volume13, No. 2. pp. 87–110, May 2003.

Tubbs, J., “An Overview of the CFAST Computer Model,” NFPA Update, Issue 840, p. 5,

December/January 2001.

C-1

APPENDIX C. SOURCES OF FIRE

This appendix discusses the various topics related to fire phenomena.

C.1 Heat Sources

Heat sources may vary widely in size, intensity, and duration. For instance, a tiny spark, a hot pin

head, an exposure fire, and sun are all heat sources as are the following representative examples:

• A paper match contains about 1 kilojoule (kJ) of heat energy released at a heat of about 45

watts (W).

• A standard laboratory candle contains about 1,500 kJ of heat energy released at a heat

power of about 50 W.

• A small wooden match contains about 1.5 kJ of heat energy released at a heat of about 50 W.

• A large wooden safety match contains about 3 kJ of heat energy released at a heat of about

90 W.

• A common butane-type cigarette lighter contains about 230 kJ of heat energy. A 10-cm

flame releases energy at a power of about 150 W; a 5-cm flame about 90 kW.

• A handheld plumber’s propane torch contains up to 20 MJ of heat energy. A 10-cm flame

releases energy at a power of about 1,800 W, or 1.8 kW.

• The heat energy required to ignite a flammable gas or vapor may be as low as

0.3 millijoules (mj).

• The heat energy required to ignite a flammable dust cloud may be as low as 20 mJ.
C-2

Table C.1-1 summarizes the common engineering terms and symbols related to heat sources, as

they apply to fire hazard analysis.

Table C.1-1. Common Engineering Terms Related to Heat Sources

Term Term

Symbol*

Basic Unit Recommended Units

Symbol Name

Heat quantity is the total amount of heat

energy released by the heat source.

Q joules kJ Kilojoules

Heat flux is the rate of heat energy released

from the igniter per second.

watt W watt

Heat flux density is the amount of heat energy

per unit area emitted from the heat source per

second.

watt per

square

meter

kW/m kilowatt per 2

square meter

Heat intensity is the temperature of a heat

source.

T Kelvin K Kelvin

Duration is the length of time between any

two events (e.g., initial ignition to full room

involvement). When a duration is specified,

the beginning and ending events should be

identified. Duration can also be used to

represent the length of time the heat source is

present.

t second s second

*In fire protection engineering, Q and q are usually reserved for heat energy. Lower case t is conventionally used

for time; capital T is usually used for temperature, but never time.

C.1.1 Reference

“SI Units Fire Protection Engineering,” 1980 Report of the Measurement of Fire Phenomena

Committee, Society of Fire Protection Engineers (SFPE), Boston, Massachusetts, March 1980.
C-3

C.2 Incident Heat

Table C.2-1 summarizes the common engineering terms and symbols related to incident heat

(heat arriving at the surface of the target fuel).

Table C.2-1. Incident Heat

Term Term

Symbol

Basic Unit Recommended Units

Symbol Name

Incident heat flux is the heat energy arriving at

the target fuel surface from the igniter per

second.

watt W watt

Incident heat flux density is the amount of heat

energy per unit area arriving at the target fuel

surface from the igniter per second.

watt per

square

meter

kW/m kW/m 2 2

Heat intensity is the incident temperature

near the target fuel surface.

T Kelvin K Kelvin

Incident duration is the length of time the heat

is received at the target fuel surface.

t second s second

C.2.1 Reference

“SI Units Fire Protection Engineering,” 1980 Report of the Measurement of Fire Phenomena

Committee, Society of Fire Protection Engineers (SFPE), Boston, Massachusetts, March 1980.
C-4

C.3 Target Fuel

Table C.3-1 summarizes the common engineering terms related to target fuel, focusing on heatproducing materials (i.e., combustibles) that may be driven to ignition by the incident heat source.

Table C.3-1. Target Fuel

Term* Term

Symbol

Basic Unit Recommended Units

Symbol Name

Heat power resistance is the maximum heat

energy that the exposed surface of an initial

target fuel can receive per second without

causing initial ignition.

watt W watt

Heat power density resistance is the amount

of heat energy per unit area received from an

igniter (heat source) each second without

causing ignition.

watt per

square

meter

W/m kilowatt per 2

square meter

Heat Intensity resistance is the maximum

surface temperature that the target fuel will

tolerate without experiencing self-sustained

burning with a pilot flame present.

T Kelvin K Kelvin

Duration resistance is the length of time a

target fuel can receive heat energy from an

igniter at a given level without igniting.

t second s second

*Target fuels generally respond on a time and energy basis. The higher the energy, the lower the time to ignition. This

phenomenon is extremely complex (e.g., it depends on geometry, heat balance, and pilot ignition).

C.3.1 Reference

“SI Units Fire Protection Engineering,” 1980 Report of the Measurement of Fire Phenomena

Committee, Society of Fire Protection Engineers (SFPE), Boston, Massachusetts, March 1980.
C-5

C.4 Flame/Heat Growth

Table C.4-1 summarizes common engineering terms related to flame/heat growth, focusing on

burning within a space, room, or enclosure.

Table C.4-1. Flame/Heat Growth

Term Term

Symbol

Basic Unit Recommended Units

Symbol Name

Heat flux is the heat energy released from the

igniter per second.

watt MW megawatt

Heat flux density is the amount of heat energy per

unit area delivered from the burning material into the

surrounding space per second.

watt per

square

meter

kW/m kilowatt per 2

square meter

Heat intensity is the temperature within the burning

space. The location of this reading within the space

should be identified.

T Kelvin K Kelvin

Duration is the length of time between two identical

events during the fire growth within the space (e.g.,

time from ignition to first steady flame out the door).

t Second s kilo-second

Duration to full room involvement is the length of

time the fire takes to reach full room involvement

(from ignition).

t Second s kilo-second

Ventilation rate is the volume of air (oxygen)

entering the burning space per second.

m m /s cubic meters 3

per second

C.4.1 Reference

“SI Units Fire Protection Engineering,” 1980 Report of the Measurement of Fire Phenomena

Committee, Society of Fire Protection Engineers (SFPE), Boston, Massachusetts, March 1980.
C-6

C.5 Fire Resistance

The fire resistance of a building may be defined as (1) its ability to withstand exposure to fire

without losing its load bearing function and (2) its ability to act as a barrier to the spread of fire.

These two abilities confine the fire to the compartment where it started and provide time for people

to evacuate a building before it collapses as a result of a fire. Before the room is fully involved, the

temperatures are relatively low and they have a negligible influence on the fire resistance of

building elements. The risk that structural members or fire barriers will fail actually begins when

the fire reaches the fully developed stage. During this stage, temperatures of 1,300 K or 1,027 °C

(1,881 °F) or higher can be reached, and the heat transferred to building elements may

substantially reduce their strength and ability to perform as a fire barrier. This risk also continues

to exist during the decay period of the fire.

The behavior of fire-exposed building elements depends, in part on the fire severity and in part on

the properties of the fire-exposed elements. The following tables summarize the most important

quantities that determine fire severity and the fire performance of building elements.

Table C.5-1. Common Engineering Terms Related to Fire Severity

Term Symbol Basic Unit Recommended Units

Symbol Name

Total load is the total amount of heat energy

available for possible release.

Q joules kJ kilojoules

Heat load density is the amount of heat energy

available possible release per unit area (floor or

bounding room surface area).

joule per square

meter

MJ/m megajoule 2

per square

meter

Heat flux density is the amount of heat energy

per unit area emitted from the heat source per

second.

 watt MW magawatt

Heat intensity is the temperature of the fire.

The specific point of measurement should be

identified (e.g., flame temperature, average

ceiling temperature, average hot gas layer

temperature).

T Kelvin K Kelvin

Duration of severity is the length of time heat

is produced by the fire that could expose

building elements to the fire.

t second ks kilosecond

Opening factor is the measure of the rate of

temperature increase associated with the fire,

defined as the area of the openings multiplied

by the square root of the height of the openings,

divided by the total bounding surface area of

the room.

F square root

meter

square root

meter

Emissivity is the ratio of the intensity of

radiation emitted by the fire to that emitted by a

blackbody of the same temperature.

dimensionless - -
C-7

Table C.5-2. Common Engineering Terms Related to Fire Performance

Term Term

Symbol

Basic Unit Recommended Units

Symbol Name

Heat load resistance is the heat load

required to cause the failure of a structural

member or fire barrier.

Qrjoules MJ megajoules

Heat flux density is the amount of heat

energy received from the fire per unit area of

the element per unit time.

watt per square

meter

kW/m kilowatt per 2

square meter

Heat intensity is the temperature of the

element at various locations during exposure

to fire.

T Kelvin K Kelvin

Thermal conductivity is the length of time

the fire produces heat that could expose

building elements to the fire.

k watt per meter

Kelvin

W/m-k watt per

meter Kelvin

Specific heat capacity is the heat

necessary to increase the temperature of

unit mass one degree

p

c joule per

kilogram Kelvin

kJ/Kg-K kilojoule per

kilogram

Kelvin

Density is the mass per unit volume of a

material.

kilogram per

cubic meter

kg/m kilogram per 3

cubic meter

Thermal diffusivity is one of the quantities

that determine the rate of temperature

increase in a material at points away from the

surface. It is equal to the thermal conductivity

divided by the product of the specific heat and

density

square meter

per second

mm /s square 2

millimeter

second

Emissivity absorbed is the ratio of the

intensity of radiation absorbed by the element

to that absorbed by a blackbody of the same

temperature.

dimensionless - -

Coefficient of thermal expansion (linear) is

the expansion of length per unit degree

increase in temperature.

reciprocal

degree Kelvin

1/K reciprocal

degree

Kelvin

Modulus of elasticity is a measure of elastic

deformation, defined as the stress needed to

produce a unit strain.

E Pascal MPa megapascal

Yield strength is the stress at which material

exhibits a specified permanent deformation.

Fy Pascal MPa megapascal

Ultimate strength is the highest stress a

material can sustain before its ruptures.

Fu Pascal MPa megapascal
C-8

C.5.1 Reference

“SI Units Fire Protection Engineering,” 1980 Report of the Measurement of Fire Phenomena

Committee, Society of Fire Protection Engineers (SFPE), Boston, Massachusetts. March 1980.

C.6 Fire Resistance/Endurance Ratings

This section identifies some of the most common fire-resistance ratings used in construction and

industry. “A,” “B,” and “C” ratings were originally defined by the Safety of Lives at Sea (SOLAS)

regulations. Most tests utilize a test specific furnace which simulates a cellulosic fire exposure

(slower growing fire but could ultimately grow hotter than a hydocarbon fire). Specific hydrocarbon

fire exposures for pool and jet fires have recently evolved.

Fire Barriers (NFPA 251, “Fire Tests of Building Construction and Materials”)

The average temperature increase of any set of thermocouples for each class of element protected

is more than 121 °C (250 °F) above the initial temperature; or the temperature increase of any one

thermocouple of the set for each class of element protected is more than 163 °C (325 °F) above

the initial temperature. Where required by the conditions of acceptance, a duplicate specimen shall

be subjected to a fire exposure test for a period equal to one-half of that indicated as the resistance

period in the fire endurance test, but not for more than 1 hour. Immediately there after, the

specimen shall be subjected to the impact, erosion, and cooling effects of a hose stream directed

first at the middle and then at all parts of the exposed face, with changes in direction made slowly.

However, The hose stream test shall not be required in the case of construction having a resistance

period, as specified in the fire endurance test, of less than 1 hour.

A Barriers (SOLAS or Title 46, Section 72.05–75.10, of the Code of Federal Regulations)

• A 0 Cellulosic Fire, 60-minute barrier against flame/heat passage, no temperature

insulation.

• A 15 Cellulosic Fire, 60-minute barrier against flame/heat passage, 15-minute temperature

insulation.

• A 30 Cellulosic Fire, 60-minute barrier against flame/heat passage, 30-minute temperature

insulation.

• A 60 Cellulosic Fire, 60-minute barrier against flame/heat passage, 60-minute temperature

insulation.

Class A divisions are those divisions formed by decks and bulkheads that comply with the following:

• constructed of steel or material of equivalent properties

• suitably stiffened

• constructed to prevent the passage of smoke and flame for a 1-hour standard fire test

• insulated with approved noncombustible materials so that the average temperature of the

unexposed side will not rise more than 180 °C (356 °F) above the original temperature

within the time listed (A60: 60 minutes; A30: 30 minutes; A15: 15 minutes; A0: 0 minutes)
C-9

B Barriers (SOLAS or Title 46, Sections 72.05–72.10, of the Code of Federal Regulations)

• B 0 Cellulosic Fire, 30-minute barrier against flame/heat passage, no temperature

insulation.

• B 15 Cellulosic Fire, 30-minute barrier against flame/heat passage, 15-minute temperature

insulation.

Class B divisions are those divisions formed by decks and bulkheads that comply with the following:

• constructed to prevent the passage of flame for a 30-minutes standard fire test

• have an insulation layer such that the average temperature on the unexposed side will not

rise more than 139 °C (282 °F) above the original temperature, nor will the temperature at

any one point, including any joint, rise more than 225 °C (437 °F) above the original

temperature (B15: 15 minutes; B0: 0 minutes)

• constructed of noncombustible materials

C Barriers (SOLAS or Title 46, Sections 72.05–72.10 of the Code of Federal Regulations)

• C construction of noncombustible materials; not rated to provide any smoke, flame, or

temperature passage restrictions.

H Barriers (UL 1709)

An exposure rating to a hydrocarbon (petroleum) fire is typically given one of the following H ratings:

• H 0 Hydrocarbon Fire, 120-minute barrier against flame/heat passage, no temperature

insulation.

• H 60 Hydrocarbon Fire, 120-minute barrier against flame/heat passage, 60-minute

temperature insulation.

• H 120 Hydrocarbon Fire, 120-minute barrier against flame/heat passage, 120-minute

temperature insulation.

• H 240 Hydrocarbon Fire, 120-minute barrier against flame/heat passage, 240-minute

temperature insulation.

J Ratings

Jet fire exposure or impingement (“J” ratings) are specified by some vendors or property owners

for resistance to hydrocarbon jet fire exposures. Currently, no standardized test or test specification

has been adopted by an industry or governmental body. Some recognized fire testing and

experimental laboratories (SINTEF, Shell Research, etc.) have conducted extensive research on

jet fire exposures and have proposed a test standard based on these studies (Ref. Offshore

Technology Report OTO 93028, “Interim Jet Fire Test Procedure for Determining the Effectiveness

of Passive Fire Protection Materials”).
C-10

Fire Doors (NFPA 252, “Standard Methods of Tests of Door Assemblies”)

A fire door assembly, which can consist of single doors, doors in pairs, special-purpose doors (e.g.,

dutch doors, double-egress doors), or multisection door assembly for which a fire protection rating

is determined and that is intended for installation in door openings in fire-resistive walls and

provides a specific degree of fire protection to the opening.

The fire test can be conducted until the desired fire protection rating period is reached or until failure

to meet any of the performance criteria specified in Chapter 5 of NFPA 252 as follows:

• 0.3 hour (20 minutes), Cellulosic fire

• 0.5 hour (30 minutes), Cellulosic fire

• 0.75 hour (45 minutes), Cellulosic fire

• 1.0 hour (60 minutes), Cellulosic fire

• 1.5 hour (90 minutes), Cellulosic fire

• 3.0 hour (180 minutes), Cellulosic fire

• Over 3.0 hours (in hourly increments), Cellulosic fire

Except for 20-minute rated door assemblies, for which it is optional, immediately following the fire

endurance test, the door test assembly shall be subjected to the impact, erosion, and cooling

effects of a hose stream. Temperature increases are listed at 121 °C, 232 °C, and 343 °C (250 °F,

450 °F, and 650 °F); absence of a temperature rating indicates an increase of more than 343 °C

(650°F) on the unexposed surface of the door after 30 minutes of testing.

Fire Windows (NFPA 257, “Standard on Fire Test for Window and Glass Block Assemblies”)

Fire ratings of windows were normally limited to the failure of wired glass at approximately 870 °C

(1,600 °F); however, advances in glazing technology have increased the available fire-resistance

ratings of window assemblies, as follows:

• 0.3 hour (20 minutes), Cellulosic fire

• 0.5 hour (30 minutes), Cellulosic fire

• 0.75 hours(45 minutes), Cellulosic fire

Higher ratings are also available based on the application of other fire-resistance standard fire tests

(NFPA 251, “Fire Tests of Building Construction and Materials”).

• 1.0 hour (60 minutes), Cellulosic fire

• 1.5 hour (90 minutes), Cellulosic fire

• 3.0 hours (180 minutes), Cellulosic fire

• Over 3.0 hours (in hourly increments), Cellulosic fire

Within 2 minutes following the fire endurance test, the fire-exposed side of the fire window

assembly is subjected to the impact, erosion, and cooling effects of a standard hose stream.
C-11

Fire Dampers (UL Std. 555)

The fire test can be conducted on the fire dampers until the desired fire protection rating period is

reached or until failure to meet any of the performance criteria specified in UL Standard 555 as

follows:

• 0.3 hour (20 minutes), Cellulosic fire

• 0.75 hour (45 minutes), Cellulosic fire

• 1.0 hour (60 minutes), Cellulosic fire

• 1.5 hours (90 minutes), Cellulosic fire

Smoke Dampers (UL Std. 555S)

Smoke dampers are specified on the basis of the leakage class, maximum pressure, maximum

velocity, installation mode (horizontal or vertical), and degradation test temperature of the fire.

Roof Coverings (NFPA 256, “Standard Tests of Fire Tests of Roof Coverings”)

The fire test can be conducted on the fire dampers until the desired fire protection rating period is

reached or until failure to meet any of the performance criteria specified in NFPA Standard 256 as

follows:

• Class A: flame spread less than 6 feet (1.82 meters)

• Class B: flame spread less than 8 feet (2.44 meters)

• Class C: flame spread less than 13 feet (3.96 meters)

For all classes of roof coverings, there is to be no significant lateral flame spread, no flying brands

or particles are to continue to flame or glow after reaching the floor, no flaming is to be produced

on the underside of the deck of the test sample, and the roof deck should not be exposed.
C-12

Fusible Links

Fusible links are available in temperature ratings of 51.6 °C–260 °C (125 °F–500 °F) and in various

load ratings.

The following tables summarize the fire-resistance test standards for building materials, aerosol,

liquid paints, and plastics.

Table C.6-1. Fire-Resistance Test Standards for Building Materials

Organization and

Test Specification

Name of Test Sample Property Measured

ASTM E69 Crib test Treated wood Combustible properties

ASTM E84 Surface burning of

building materials

Building materials Flame spread index,

Smoke developed

ASTM E108 Building

Codes, 

UBC 32-7

UL-790

Fire rating of roof

coverings

Coatings, shingle

shake, insulation,

etc.

Spread of flame,

intermittent flame,

burning brand, flying

brand

ASTM E119,

NFPA 251

Building and

construction materials

Walls, partitions,

columns, horizontal

assemblies

Flame and hot gas

passage, structural

stability

ASTM E136 Behavior of materials

in vertical tube

furnace

Building materials Combustibility or

non-combustibility

of building materials

ASTM E160 Crib test Treated wood Combustible properties

ASTM E162 Surface flammability

of materials using a

radiant heat source

Sheet laminates,

tiles, fabrics,

liquids, films

Flame spread index,

visual characteristics

ASTM E648

NFPA 253

Critical radiant flux

of floor covering

systems

Floor covering

systems

Critical radiant flux

at flameout

ASTM E662 Specific optical

density of smoke

generated by solid

materials

Solid materials (e.g.,

wood, plastic)

Specific optical density

ASTM E970, CPSC

HH-I-515D,

HH-I-521F,

HH-I-1030B

16CFR 1209.6

Critical radiant flux

of attic insulation

Exposed attic floor

insulation

Critical radiant flux

at flameout
Table C.6-1. Fire-Resistance Test Standards for Building Materials

Organization and

Test Specification

Name of Test Sample Property Measured

C-13

ASTM E2010,

NFPA 257

Positive pressure of

windows

Windows, glass block

assemblies

Retention in place

ASTM E2074,

NFPA 252

Fire test of doors Doors: side hinged,

pivoted, swinging,

sliding, overhead

Retention in place

Organization and

Test Specification

Name of Test Sample Property Measured

NIST

NBSIR-82-2532

Combustion product

toxicity

All materials Inhalation toxicity

NY State, Dept. of

State 15,1120

Modified Pittsburgh

Test

All materials Inhalation toxicity

Table C.6-2. Fire-Resistance Test Standards for Aerosol and Liquid Paints

Organization and

Test Specification

Name of Test Sample Property Measured

ASTM

D56, D92, D93, D1310

Flash point Liquids Flash point

ASTM

D3243

D3278

Flash point-set a flash Liquids, aviation

turbine fuels

Flash point

ASTM 

D1360

Fire retardancy of paint Paint Fire retardancy

FHSA

ASTM-API

16 CFR 500.43

Flash point

(tag open cup)

Aerosols Flash point

FHSA

CSMA

16 CFR 500.45

Flame projection Aerosols Flame projection

CSMA

Aerosol Guide

Drum test Aerosols Inhalation toxicity

NIST

NBSIR-82-2532

Combustion product

toxicity

All materials Inhalation toxicity

NY State, Dept. of

State 15, 1120

Modified Pittsburgh test All materials Inhalation toxicity
C-14

Table C.6-3. Fire-Resistance Test Standards for Plastics

Organization and

Test Specification

Name of Test Sample Property Measured

ASTM

D568

Flammability of plastics

0.050" and under

Plastic sheets and film non-burning, selfextinguishing, burning

rate, visual

characteristics

ASTM

D635

Rate of burning 

(self- supporting

plastics)

Rigid plastics Burning rate, visual

characteristics

ASTM 

D757

Incandescence

resistance (rigid plastics) 

Rigid plastics Burning rate, visual

characteristics

ASTM

D1929,

Procedure B

Ignition properties of

plastics

Plastic sheets and

films, thermo-plastic

pellets

Flash ignition

temperature, 

self-ignition

temperature, visual

characteristics

ASTM

D2843

Smoke density from the

burning of plastics

Plastic material Percent of light

absorption

Bureau of Ships

NObs 84814

MIL-M-14g

Flammability and toxicity Generally melamine

plastic; any material

Flash ignition, selfignition, composition and

toxicity gases evolved

CPSC

CS 192-53

16- CFR 1611.4

ASTM D-1433

Flammability of plastic

film

Plastic films, coated

fabrics

Ignition time, rate of

burning

Federal Test

Method Std.

FTMS 406

Method 2023

Flame resistance of

plastics

Plastics difficult to

ignite

Ignition time,

burning time,

flame travel

NIST

NBSIR-82-2532

Combustion product

toxicity

All materials Inhalation toxicity

NY State, U.S.

Department of State

15,1120

Modified Pittsburgh test All materials Inhalation toxicity

C.6.1 Reference

Nolan, D.P., Encyclopedia of Fire Protection, Delmar Publishers, Albany, New York, 2001.
C-15

C.7 FIRE TEST STANDARDS

This section lists the empirical standard tests for fire-resistance, flame spread, and flammability.

The following list identifies the empirical standard fire-resistance tests.

Test Standard Title

API 6 FA Fire Tests for Valves

API 607 Fire Tests of Quarter-Turn Valves

ASTM E119 Fire Test of Building Constructions and Materials

ASTM E814 Fire Tests of Through-Penetration Fire Stops (Penetration Seals)

ASTM E1529 Determining Effects of Large Hydrocarbon Pool Fires on Structural Members

and Assemblies

ASTM E1623 Determination of Fire and Thermal Parameters of Materials, Products, and

Systems Using an Intermediate-Scale Calorimeter (ICAL)

ASTM E2010 Fire Tests of Window Assemblies

ASTM E2074 Fire Tests of Door Assemblies

BS 476, Part 20, 21 Fire Test of Building Construction and Materials, Window Assemblies, and

Door Assemblies (BSI)

ISO 834 Fire Tests of Building Constructions and Materials

ISO 3008 Fire Tests of Door Assemblies

ISO 3009 Fire Tests of Window Assemblies

NFPA 251 Fire Tests of Building Constructions and Materials

NFPA 252 Fire Tests of Door Assemblies

NFPA 257 Fire Tests of Window Assemblies

UL 9 Fire Test of Window Assemblies

UL 10A/10B/10C Fire Test of Door Assemblies

UL 72 Fire Resistance of Record Protection Equipment

UL 155 Fire Test of Door Assemblies

UL 263 Fire Test of Building Construction and Materials

UL 555 Fire Dampers

UL 555C Ceiling Dampers

UL 555S Leakage-Rated Dampers for use in Smoke Control Systems

UL 1479 Fire Test of Through Penetration Fire Seals

UL 1709 Rapid Rise Fire Tests of Protection Materials for Structural Steel

UL 2079 Tests for Fire Resistance of Building Joint Systems

UL 2085 Insulated Above Ground Tanks for Flammable and Combustible Liquids
C-16

The following list identifies the empirical standard flame spread tests.

Test Standard Title

ASTM E84 Surface Burning Characteristics of Materials

ASTM E162 Surface Flammability of Materials Using a Radiant Heat Energy Source

ASTM E648 Critical Radiant Flux of Floor Covering Systems Using a Radiant Heat

Energy Source

ASTM E970 Critical Radiant Flux of Exposed Attic Floor Insulation Using a Radiant Heat

Energy Source

IEEE 383 Standard for Type Test of Class 1E Electric Cables, Field Splices, and

Connections for Nuclear Power Generating Stations

IEEE 634 Standard Cable Penetration Fire Stop Qualification Test

IEEE 1202 Standard for Flame Testing of Cable for Use in Cable Tray in Industrial and

Commercial Occupancies

NFPA 255 Surface Burning Characteristics of Materials

NFPA 262 Fire and Smoke Characteristics of Electrical and Optical Fiber Cables in Air

Handling Spaces

NFPA 265 Full-Scale Test for Room Fire Growth Contribution of Textile Wall Coverings

UL 910 Fire and Smoke Characteristics of Electrical and Optical Fiber Cables in Air

Handling Spaces

UL 1256 Under-Deck Roof Construction Test

UL 1581 Reference Standard for Electrical Wires, Cables, and Flexible Cords, 1080,

VW-1 Vertical Wire Flame Test.

UL 1581 Reference Standard for Electrical Wires, Cables, and Flexible Cords, 1160,

UL Vertical-Tray Flame Test. 

UL 1715 Room Fire Test Standard of Interior of Foam Plastic Systems

UL 1820 Fire Test of Pneumatic Tubing for Flame and Smoke Characteristics

UL 1887 Fire Test of Plastic Sprinkler Pipe for Flame and Smoke Characteristics
C-17

The following list identifies the empirical standard small-scale flammability tests.

Test Standard Title

16 CFR 1610.4 (CPSC) Flammability of Wearing Apparel

16 CFR 1630.4 (CPSC) Flammability of Finished Textile Floor Covering Materials

16 CFR 1653.4 (CPSC) Flammability of Finished Textile Floor Covering Materials

ASTM C 1166 Flame Propagation of Dense and Cellular Elastomeric Gaskets and

Accessories

ASTM D635 Rate of Burning and/or Extent and Time of Burning of

Self-Supporting Plastics in a Horizontal Position

ASTM D1692 Flammability of Plastic Sheeting and Cellular Plastics

ASTM D1929 Ignition Properties of Plastics

ASTM D2584 Ignition Loss of Cured Reinforced Plastics

ASTM D2859 Flammability of Finished Textile Floor Covering Materials

ASTM D2863 Measuring the Minimum Oxygen Concentration to Support

Candle-Like Combustion of Plastics

ASTM D3801 Method for Measuring the Comparative Extinguishing Characteristics

of Solid Plastics in a Vertical Position

ASTM D3806 Small-Scale Evaluation of Fire-Retardant Paints

ASTM D3894 Evaluation of Fire Response of Rigid Cellular Plastics Using a Small

Corner Configuration

ASTM D4804 Flammability Characteristics of Nonrigid Solid Plastics

ASTM D4986 Horizontal Burning Characteristics of Cellular Polymeric Materials

ASTM D5048 Comparative Burning Characteristics and Resistance to

Burn-Through of Solid Plastics Using a 125-mm Flame

ASTM E136 Behavior of Materials in a Vertical Tube Furnace at 750 °C

ASTM E662 Specific Optical Density of Smoke Generated by Solid Materials

ASTM E1354 Heat and Visible Smoke Release Rates for Materials and Products

Using an Oxygen Consumption Calorimeter

ASTM F501 Aerospace Materials Response to Flame, With Vertical Test

Specimen

Boston Fire Dept. Code 

Sec.11.2 & 11.3 Fire Tests of Flame Resistant Textiles and Films 

Boston Fire Dept. IX-I Classification Fire Tests of Fabrics

Boston Fire Dept. IX-II Mattresses, Portable Mattresses, and Mattress Pads

Calif. Title 19 Fire Tests of Flame-Resistant Textiles & Films; Intermediate-Scale

CS 191 Flammability of Wearing Apparel

FAA OSU Rate of Heat Release Evaluation

FAR 25.853 Test Procedure of Showing Compliance with §§ 25.853, 25.855 and

25.1359 (Aircraft Compartment Interior Fire Test)

FMVSS 302 Flammability of Interior Materials—Passenger Cars, Multipurpose

Passenger Vehicles, Trucks, and Buses

FTMS 191 Flame Resistance of Cloth

ISO 5660 Heat and Visible Smoke Release Rates for Materials and Products

Using an Oxygen Consumption Calorimeter
C-18

Test Standard Title

NFPA 253 Critical Radiant Flux of Floor Covering Systems Using a Radiant

Heat Energy Source

NFPA 258 Specific Optical Density of Smoke Generated by Solid Materials

NFPA 263 Rate of Heat Release Evaluation

NFPA 264 Heat and Visible Smoke Release Rates for Materials and Products

Using an Oxygen Consumption Calorimeter

NFPA 701 Fire Tests for Flame Resistant Textiles and Films

NFPA 702 Flammability of Wearing Apparel

NFPA 703 Fire-Retardant Treated Wood

UL 94 Flammability of Plastic Materials

UL 214 Tests for Flame Propagation of Fabrics and Films

UL 1975 Fire Tests for Foamed Plastics Used for Decorative Purposes
D-1

APPENDIX D. NRC DOCUMENTS RELATED TO FIRE PROTECTION

This appendix provides the various NRC reference documents related to fire protection.

D.1 Code of Federal Regulations Related to Nuclear Regulatory Commission

Fire Protection

The Code of Federal Regulations is a codification of the general and permanent rules published

in the Federal Register by the Executive departments and agencies of the Federal Government.

The code is divided into 50 titles, which represent broad areas subject to Federal regulation. Each

title is divided into chapters, which usually bear the name of the issuing agency. Each chapter is

further subdivided into parts covering specific regulatory areas. Title 10, “Energy,” is composed of

four volumes. These volumes are subdivided as Parts 1–50, 51–199, 200–499, and 500–end. The

first and second volumes containing parts 1–199 comprise Chapter I, “Nuclear Regulatory

Commission.” The U.S. Nuclear Regulatory Commission sets requirements for the safe operation

of commercial nuclear power reactors, licenses the construction and operation of the reactors, and

inspects them to ensure that they are operating safely within the agency’s regulations. NRC

resident inspectors are stationed at each nuclear power plant and additional safety reviews are

done by experts from NRC regional offices and headquarters.

(1) Code of Federal Regulations, Title 10, “Energy,” Section 50.12, “Specific Exemption”, U.S.

Government Printing Office, Washington DC.

(2) Code of Federal Regulations, Title 10, “Energy,” Section 50.48, “Fire Protection,” U.S.

Government Printing Office, Washington DC.

(3) Code of Federal Regulations, Title 10, “Energy,” Part 50, Appendix A, “General Design

Criterion 3 - Fire Protection,” U.S. Government Printing Office, Washington DC.

(4) Code of Federal Regulations, Title 10, “Energy,” Part 50, Appendix R, “Fire Protection

Program for Nuclear Power Facilities Operating Prior to January 1, 1979,” U.S. Government

Printing Office, Washington DC.

(5) Code of Federal Regulations, Title 10, “Energy,” Part 54, “Requirements for Renewal of

Operating Licenses for Nuclear Power Plants,” U.S. Government Printing Office,

Washington DC.
D-2

D.2 Branch Technical Positions Related to Fire Protection

A branch technical position (BTP) sets forth a solution found to be acceptable by the NRC staff in

dealing with a safety problem or safety-related problem. BTPs are included in the standard review

plan (SRP) to serve as guides for the NRC staff reviewers as a means of achieving uniformity of

interpretation and application of NRC requirements. Like regulatory guides, a BTP sets forth an

acceptable method of complying with applicable regulations and not the only acceptable method.

The BTPs related to fire protection has been developed to provide comprehensive review guidance

for nuclear power plant (NPP) fire protection programs (FPPs). These guidance identifies the

scope and depth of fire protection that the Commission considers acceptable for NPPs. BTPs may

be used for review of existing fire protection programs and program elements, proposed changes

to existing programs that are subject to NRC review, new applications, fire vulnerability analyses

[e.g., fire probabilistic risk assessments (PRA)], and programs for plant shutdown and

decommissioning. Risk-informed and performance-based alternatives to the guidance presented

in this regulatory guide may be acceptable and are evaluated on a case-by-case basis.

(1) BTP APCSB 9.5-1, “Guidelines for Fire Protection for Nuclear Power Plants,” May 1, 1976,

February 24, 1977.

(2) Appendix A to BTP APCSB 9.5-1, “Guidelines for Fire Protection for Nuclear Power Plants,

Docketed Prior to July 1, 1976,” (August 23, 1976), February 24, 1977.

(3) BTP ASB 9.5-1, “Guidelines for Fire Protection for Nuclear Power Plants,” Revision 1,

March 1979.

(4) BTP CMEB 9.5-1 (Formerly ASB 9.5-1), “Guidelines for Fire Protection for Nuclear Power

Plants,” Revision 2, July 1981.

(5) BTP SPLB 9.5-1, (Formerly CMEB 9.5-1), “Guidelines for Fire Protection for Nuclear Power

Plants,” Draft, Revision D, December 2002.

Abbreviations:

APCSB

ASB

CMEB

SPLB

Auxiliary and Power Conversion Systems Branch

Auxiliary Systems Branch

Chemical and Mechanical Engineering Branch

Plant Systems Branch
D-3

D.3 NRC Regulatory Guides Related to Fire Protection

The Regulatory Guide (RG) provides guidance to licensees and applicants on implementing specific

parts of the NRC's regulations, techniques used by the staff in evaluating specific problems or

postulated accidents, and data needed by the staff in its review of applications for permits or

licenses. Some guides delineate techniques used by the NRC to evaluate specific situations. Other

provide guidance to applicants concerning information needed by the NRC in its review of

construction permit (CP) and operating license (OL) applications. Many guides refer to or endorse

national codes or standards [e.g., American Society of Mechanical Engineers (ASME), American

National Standard Institute (ANSI), National Fire Protection Association (NFPA) etc.] that are

developed by recognized national organizations. The guides are issued in the following 10 broad

divisions:

(1) Power Reactors

(2) Research and Test Reactors

(3) Fuels and Materials Facilities

(4) Environmental and Siting

(5) Materials and Plant Protection

(6) Products 

(7) Transportation

(8) Occupational Health

(9) Antitrust and Financial Review

(10) General

Draft RGs are issued for public comment in the early stages of the development of a regulatory

position. They have not received complete staff review and do not present an official NRC staff

position until finalized and issued. Table D.3-1 provide the list of RGs related to fire protection.

Table D.3-1. NRC Regulatory Guides Related to Fire Protection

Regulatory

Guide

Title Issue Date

3.16 General Fire Protection Guide for Plutonium Processing and Fuel

Fabrication Plants

January

1974

1.39 Housekeeping Requirements for Water-Cooled Nuclear Power Plants,

Revision 2

September

1977

1.120 Fire Protection Guidelines for Nuclear Power Plants, Revision 1 November

1977

“Withdrawn

August 2001)

1.52 Design, Testing, and Maintenance Criteria for Post -accident

Engineered Safety-Feature Atmosphere Cleanup System Air Filtration

and Adsorption Units of Light-Water-Cooled Nuclear Power Plants,

Revision 2

March 1978

1.75 Physical Independence of Electric Systems, Revision 2 September

1978
Table D.3-1. NRC Regulatory Guides Related to Fire Protection

Regulatory

Guide

Title Issue Date

D-4

1.91 Evaluations of Explosions Postulated To Occur on Transportation

Routes Near Nuclear Power Plants, Revision 1

February

1978

RTS 809-5 Qualification Test for Cable Penetration Fire Stops for Use in Nuclear

Power Plants

July 

1979

1.175 An Approach for Plant-Specific, Risk-Informed Decisionmaking: Inservice

Testing, August 1998, RS809-5 Qualification Test for Cable Penetration

Fire Stops for Use in Nuclear Power Plants

September

1979

RS 902-4 Fire Stops for Use in Nuclear Power Plants (Second Proposed Revision

3 to Regulatory Guide 1.33) Quality Assurance Program Requirements

(Operation)

November

1980

1.10 Emergency Planning and Preparedness for Nuclear Power Reactors,

Revision 3

August 

1992

1.174 An Approach for Using Probabilistic Risk Assessment in Risk-Informed

Decisions On Plant-Specific Changes to the Licensing Basis

July 

1998

1.184 Decommissioning of Nuclear Power Reactors

(Draft was issued as DG-1067)

August 

2000

1.189 Fire Protection for Operating Nuclear Power Plants

(Draft was issued as DG-1097)

April 

2001

1.191 Fire Protection Program for Nuclear Power Plants during

Decommissioning and Permanent Shutdown

(Draft was issued as DG-1069)

May 

2001

DG-1110 (Proposed Revision 1 to Regulatory Guide 1.174), “An Approach for Using

Probabilistic Risk Assessment in Risk-Informed Decisions on

Plant-Specific Changes to the Licensing Basis

June 

2001

1.188 Standard Format and Content for Applications to Renew Nuclear Power

Plant Operating Licenses

(Drafts were DG-1104 issued 8/00, DG-1047 issued 8/96, Draft

DG-1009 issued 12/90) 

July 

2001

1.170.4 Fire Protection Considerations for Nuclear Power Plants

DG-1138 Risk-Informed, Performance-Based Fire Protection for Existing LightWater Nuclear Power PlantsSeptember

2004
D-5

D.4 NRC Generic Communications Related to Fire Protection

A generic communication is a transmittal to one or more classes of licensees. There are 6 types

of generic communications, i.e., administrative letters, bulletins, circulars, generic letters,

information notices, and regulatory issue summaries. Circulars were discontinued in February

1985.

D.4.1 NRC Administrative Letters Related to Fire Protection

An administrative letter (AL) is a type of generic communication issued to:

• Inform addressees of any of the following:

(1) Administrative procedure changes relating to implementation of the regulations or

NRC staff positions.

(2) The issuance of a topical report evaluation or a NUREG-type document that is not

technical in nature, does not contain a new or revised staff position, and is not

appropriate for inclusion in either a generic letter or an information notice.

(3) Changes in NRC internal procedures or organizations. 

• Request voluntary submittal of information of an administrative nature which will assist NRC

in the performance of its function.

• Announce events of interest such as workshops or Regulatory Information Conferences.

• Other purposes of a strictly administrative nature.

Table D.4-1 provide the list of administrative letters related to fire protection.

Table D.4-1. NRC Administrative Letters Related to Fire Protection

Administrative

Letter Number

Title Issue Date

94-03 Announcing An NRC Inspection Procedure On Licensee

Self-Assessment Programs For NRC Area-Of-Emphasis Inspections

03-17-1994

94-07 Distribution of Site-Specific and Site Emergency Planning

Information

05-06-1994

95-06 Relocation of Technical Specification Administrative Controls

Related to Quality Assurance

12-12-1995

96-04 Efficient Adoption of Improved Standard Technical Specifications 10-09-1996

98-02 Revisions to Event Reporting Guidelines for Power Reactors 03-17-1998

98-09 Priority for NRR Review of Risk-Informed Licensing Actions 10-30-1998

98-10 Dispositioning of Technical Specifications That Are Insufficient to

Assure Plant Safety

12-29-199
D-6

D.4.2 NRC Bulletins Related to Fire Protection

A bulletin (BL) is used to address significant issues having generic applicability that also have great

urgency. A BL requests information from, requests specified action by, and requires a written

response in accordance with Section 182.a of the Atomic Energy Act of 1954, as amended, and

10 CFR 50.54(f), from the addresses regarding matters of safety, safeguards, or environmental

significance. Addressees may be asked to take compensatory action that is commensurate with

urgency of the issue being addressed, and provide requested information and perform and submit

analyses by a specific time. A BL may not request long term actions. A BL may request new or

revised license commitments that are based on analyses performed and license-proposed

corrective action. A BL may not require license commitments. To extent that circumstances permit,

NRC staff will interact with the nuclear industry on the issue being addressed. Table D.4-2 provide

a list of NRC BLs related to fire protection.

Table D.4-2. NRC Bulletins Related to Fire Protection

BL No. Title Issue Date

75-04 Cable Fire at Browns Ferry Nuclear Power Station 03-24-1975

75-04A Cable Fire at Browns Ferry Nuclear Power Station 04-03-1975

75-04B Cable Fire at Browns Ferry Nuclear Power Station 11-03-1975

77-08 Assurance of Safety and Safeguards During an Emergency-Locking

Systems

12-28-1977

78-01 Flammable Contact-Arm Retainers in G.E. CR120A Relays. 01-16-1978

78-03 Potential Explosive Gas Mixture Accumulation Associated with BWR

Offgas System Operations

02-08-1978

81-03 Flow Blockage of Cooling Water to Safety System Components by

Corbicula Sp. (Asiatic Clam) and Mytilus Sp. (Mussel)

04-10-1981

92-01 Failure of Thermo-Lag 330 Fire Barrier System to Maintain Cabling in

Wide Cable Trays and Small Conduits Free From Fire Damage

06-24-1992

92-01

Supp-1

Failure of Thermo-Lag 330 Fire Barrier System to Perform Its Specified

Fire Endurance Function

08-28-1992
D-7

D.4.3 NRC Circulars Related to Fire Protection

A circular (CR) is a type of generic communication used to transmit information to licensees or

permit holders when the information is of safety, safeguards, or environmental interest but replies

from licensees are not necessary for IE to assess the significance of the matter. A CR does not

involve a specific response to the NRC but, rather, informs the licensees or permit holder. Table

D.4-3 provide a list of NRC CRs related to fire protection.

Table D.4-3. NRC Circulars Related to Fire Protection

Circular

Number

Title Issue Date

77-03 Fire Inside a Motor Control Center 02-28-1977

78-04 Installation Error that Could Prevent Closing of Fire Doors 05-15-1978

78-18 UL Fire Test 11-02-1978

79-13 Replacement of Diesel Fire Pump Starting Contactors 07-16-1979
D-8

D.4.4 NRC Generic Letters Related to Fire Protection

A generic letter (GL) is used to address an emergent or routine technical issue having generic

applicability that is a matter on which NRC staff has interacted with the nuclear industry and has

concluded that a genetic communication is an appropriate means to effect resolution, or a risk

significant, compliance, or adequate protection matter that NRC staff has concluded should be

brought to the attention of the nuclear industry without extensive, prior interaction. A GL may

request information from and/or request specific action by the addressees regarding matters of

safety, safeguards, or environmental significance. The addressee may ask to accomplish the

actions and report their completion by letter, with or without prior NRC approval of the action taken.

Information requests typically will be on a voluntary basis, i.e., will not require a written response

in accordance with Section 182.a of the Atomic Energy Act of 1954, as amended, and 10 CFR

50.54(f). A GL may request that the analyses be performed and, as appropriate, submitted for staff

review, that description of proposed corrective action and other information be submitted for staff

review, and that corrective actions be taken by a specified time. A GL may request new or revised

license commitments based on analyses performed and proposed corrective actions, but may not

require license commitments. Table D.4-4 provide the list of NRC GLs related to fire protection.

Table D.4-4. NRC Generic Letters Related to Fire Protection

Generic

Letter

Title Issue Date

77-02 Fire Protection Functional Responsibilities, Administrative Control and

Quality Assurance

08-29-1977

80-45 Fire Protection Rule 05-19-1980

80-48 Revision To 5/19/80 Letter On Fire Protection 05-22-1980

80-56 Commission Memorandum And Order On Equipment Qualification 06-25-1980

80-96 Fire Protection 11-14-1980

80-100 Appendix R to 10 CFR 50 Regarding Fire Protection-Federal Register

Notice

11-24-1980

80-103 Fire Protection - Revised Federal Register Notice 11-25-1980

81-12 Fire Protection Rule (45 FR 76602, November 19, 1980), February 20,

1981, and Clarification Letter

03-31-1982

82-21 Technical Specifications for Fire Protection Audits 10-06-1982

83-33 NRC Positions on Certain Requirements of Appendix R 

to 10 CFR Part 50

10-19-1983

85-01 Fire Protection Policy Steering Committee Report,January 9, 1985 (GL 85-

01 was issued only as a DRAFT for comment at public meetings which

were held in 1984. However, GL 85-01 was never issued as a final and

therefore is not available.)

01-09-1985

86-10 Implementation of Fire Protection Requirements 04-24-1986
Table D.4-4. NRC Generic Letters Related to Fire Protection

Generic

Letter

Title Issue Date

D-9

86-10

Supp-1

Fire Endurance Test Acceptance Criteria for Fire Barrier Systems Used

to Separate Redundant Safe Shutdown Trains Within the Same Fire

Area

03-25-1994 

88-12 Removal of Fire Protection Requirements from Technical Specifications 08-02-1988

88-20 Individual Plant Examination for Severe Accident Vulnerabilities 11-23-1988

88-20

Supp-1

Initiation of the Individual Plant Examination for Severe Accident

Vulnerabilities (10 CFR 50.54)

88-20

Supp-2

Accident Management Strategies for Consideration in the Individual

Plant Examination Process

 04-04-1990

88-20

Supp-4

Individual Plant Examination of External Events (IPEEE) for Severe

Accident Vulnerabilities

06-29-1991

88-20

Supp-5

Individual Plant Examination of External Events (IPEEE) for Severe

Accident Vulnerabilities - 10 CFR50.54(f)

09-08-1995

89-13 Service Water System Problems Affecting Safety-Related Equipment 07-18-1989

89-13

Supp-1

Service Water System Problems Affecting Safety-Related Equipment 04-04-1990

91-18 Information to Licensees Regarding Two NRC Inspection Manual

Sections on Resolution of Degraded and Nonconforming Conditions and

Operability

11-07-1991

91-18

Rev. 1

Information to Licensees Regarding Two NRC Inspection Manual

Sections on Resolution of Degraded and Nonconforming Conditions and

Operability

10-08-1997

92-08 Thermo-Lag 330-1 Fire Barriers 12-17-1992

93-03 Verification of Plant Records 10-20-1995

93-06 Research Results on Generic Safety Issue 106, Piping and the Use of

Highly Combustibles Gases in Vital Areas

10-25-1993

95-01 NRC Staff Technical Position on Fire Protection for Fuel Cycle Facilities 01-26-1995
D-10

D.4.5 NRC Information Notices Related to Fire Protection

An information notice (IN) is a type of generic communication used to inform the nuclear industry

of recently-identified, significant safety, safeguards, or environmental issues. Licensees are

expected to review the information for applicability to their facilities or operations and consider

actions, as appropriate, to avoid similar problems. INs do not convey changes in NRC policy or

guidance and do not recommend specific courses of action. The suggestions contained in INs do

not constitute NRC requirements and, therefore, no specific action or written response is required.

The are rapid transmittals of information that may not yet have been completely analyzed by the

NRC but that licensees should be aware of. Table D.4-5 provide the list of all INs related to fire

protection.

Table D.4-5. NRC Information Notices Related to Fire Protection

IN Number Title Issue Date

79-32 Separation of Electrical Cables for HPCI and ADS 12-18-1979

80-11 Generic Problems with ASCO Valves in Nuclear Applications Including

Fire Protection Systems

03-14-1980

80-25 Transportation of Pyrophoric Uranium 05-30-1980

81-27 Flammable Gas Mixtures in the Waste Gas Decay Tanks in PWR

Plants

09-03-1981

82-28 Hydrogen Explosion while Grinding in the Vicinity of Drained and Open

Reactor Coolant System

07-23-1982

82-53 Main Transformer Failures at the North Anna Nuclear Power Station 12-22-1982

83-41 Actuation of Fire Suppression System Causing Inoperability of

Safety-Related Equipment

06-22-1983

83-69 Improperly Installed Fire Dampers at Nuclear Power Plants 10-21-1983

83-83 Use of Portable Radio Transmitters Inside Nuclear Power Plants 12-19-1983

84-09 Lessons Learned From NRC Inspections of Fire Protection Safe

Shutdown Systems (10 CFR Part 50, Appendix R)

02-13-1984

84-09r1 Lessons Learned From NRC Inspections of Fire Protection Safe

Shutdown Systems (10 CFR Part 50, Appendix R)

03-07-1984

84-16 Failure of Automatic Sprinkler System Valves to Operate 03-02-1984

84-42 Equipment Availability For Conditions During Outages not Covered by

Technical Specifications

06-05-1984

84-92 Cracking of Flywheels On Cummins Fire Pump Diesel Engines 12-17-1984

85-09 Isolation Transfer Switches and Post-Fire Shutdown Capability 01-31-1985

85-30 Microbiologically Induced Corrosion of Containment Service Water

System

04-19-1985
Table D.4-5. NRC Information Notices Related to Fire Protection

IN Number Title Issue Date

D-11

85-85 Systems Interaction Event Resulting in Reactor System Safety Relief

Valve Opening Following a Fire-Protection Deluge System Malfunction

10-31-1985

86-13 Standby Liquid Control System Squib Valves Failure to Fire 02-21-1986

86-13

Supp-1

Standby Liquid Control System Squib Valves Failure to Fire 08-05-1985

86-17 Update of Failure of Automatic Sprinkler System Valves to Operate 03-24-1986

86-35 Fire in Compressible Material at Dresden Unit 3 05-15-1986

86-106 Feedwater Line Break 12-16-1986

86-106

Supp-1

Feedwater Line Break 02-13-1987

86-106

Supp-2

Feedwater Line Break 03-18-1987

86-106

Supp-3

Feedwater Line Break 11-10-1988

87-14 Actuation of Fire Suppression System Causing Inoperability of

Safety-Related Ventilation Equipment

03-27-1987

87-20 Hydrogen Leak in Auxiliary Building 04-20-1987

87-50 Potential LOCA at High- and Low-Pressure Interfaces from Fire

Damage

10-09-1987

88-04 Inadequate Qualification and Documentation of Fire Barrier Penetration

Seals

02-05-1988

88-04

Supp-1

Inadequate Qualification and Documentation of Fire Barrier Penetration

Seals

08-09-1988

88-05 Fire in Annunciator Control Cabinets 02-12-1988

88-45 Problems in Protective Relay and Circuit Breaker Coordination 07-07-1988

88-56 Potential Problems with Silicone Foam Fire Barrier Penetration Seal 08-04-1988

88-60 Inadequate Design and Installation of Watertight Penetration Seals 08-11-1988

88-61 Control Room Habitability - Recent Reviews of Operating Experience 08-11-1988

88-64 Reporting Fires in Nuclear Process Systems at Nuclear Power Plants 08-18-1988

89-44 Hydrogen Storage on the Roof of the Control Room 04-27-1989

89-52 Potential Fire Damper Operational Problems 06-08-1989

90-70 Pump Explosions Involving Ammonium Nitrate 11-06-1990
Table D.4-5. NRC Information Notices Related to Fire Protection

IN Number Title Issue Date

D-12

91-17 Fire Safety of Temporary Installations or Services 03-11-1991

91-20 Electrical Wire Insulation Degradation Caused Failure in a

Safety-Related Motor Control Center

03-19-1991

91-37 Compressed Gas Cylinder Missile Hazards 06-19-1991

91-47 Failure of Thermo-Lag Fire Barrier Material to Pass Fire Endurance

Test

08-06-1991

91-53 Failure of Remote Shutdown System Instrumentation Because of

Incorrectly Installed Components

09-04-1991

91-77 Shift Staffing at Nuclear Power Plants 11-26-1991

91-79 Deficiencies in the Procedures for Installing Thermo-Lag Fire Barrier

Materials

12-06-1991

91-79

Supp-1

Deficiencies Found in Thermo-Lag Fire Barrier Installation 08-04-1994

92-14 Uranium Oxide Fires at Fuel Cycle Facilities 02-21-1992

92-18 Potential for Loss of Remote Shutdown Capability During a Control

Room Fire

02-28-1992

92-28 Inadequate Fire Suppression System Testing 04-08-1992

92-46 Thermo-Lag Fire Barrier Material Special Review Team Final Report

Findings, Current Fire Endurance Tests, and Ampacity Calculation

Errors

06-23-1992

92-55 Current Fire Endurance Test Results For Thermo-Lag Fire Barrier

Material

07-27-1992

92-82 Results of Thermo-Lag 330-1 Combustibility Testing 12-15-1992

93-40 Fire Endurance Test Results for Thermal Ceramics FP-60 Fire Barrier

Material

05-26-1993

93-41 One Hour Fire Endurance Test Results for Thermal Ceramics Kaowool,

3M Company FS-195, and 3M Company Interam E-50 Fire Barrier

Systems

05-28-1993

93-71 Fire At Chernobyl Unit 2 09-13-1993

94-12 Insights Gained From Resolving Generic Issue 57: Effects of Fire

Protection System Actuation on Safety-Related Equipment

02-09-1994

94-22 Fire Endurance and Ampacity Derating Test Results for 3-hour

Fire-Rated Thermo-Lag 330-1 Fire Barriers

 03-16-1994

94-26 Personnel Hazards and Other Problems From Smoldering

Fire-Retardant Material in the Drywell of a Boiling-Water Reactor

03-28-1994
Table D.4-5. NRC Information Notices Related to Fire Protection

IN Number Title Issue Date

D-13

94-28 Potential Problems With Fire-Barrier Penetration Seals 04-05-1994

94-31 Potential Failure of Wilco, Lexan-Type HN-4-L Fire Hose Nozzles 04-14-1994

94-34 Thermo-Lag 330-660 Flexi-Blanket Ampacity Derating Concerns 05-13-1994

94-53 Hydrogen Gas Burn Inside Pressurizer During Welding 07-18-1994

94-58 Reactor Coolant Pump Lube Oil Fire 08-16-1994

94-59 Accelerated Dealloying of Cast Aluminum-Bronze Valves Caused by

Microbiologically Induced Corrosion

08-17-1994

94-86 Legal Actions Against Thermal Science, Inc., Manufacturer of

Thermo-Lag

 12-22-1994

94-86

Supp-1

Legal Actions Against Thermal Science, Inc., Manufacturer of

Thermo-Lag

11-15-1995

95-27 NRC Review of Nuclear Energy Institute, Thermo-Lag Combustibility

Evaluation Methodology Plant Screening Guide

05-31-1995

95-32 Thermo-lag 330-1 Flame Spread Test Results 08-10-1995

95-33 Switchgear Fire and Partial Loss of Offsite Power at Waterford

Generating Station, Unit 3

08-23-1995

95-36 Potential Problems with Post-Fire Emergency Lighting 08-29-1995

95-36

Supp-1

Potential Problem in Post-Fire Emergency Lighting 06-10-1997

95-48 Results of Shift Staffing Study 10-10-1995

95-49 Seismic Adequacy of Thermo-Lag Panels 10-27-1995

95-49

Supp-1

Seismic Adequacy of Thermo-Lag Panels 12-10-1997

95-52 Fire Endurance Test Results for Electrical Raceway Fire Barrier

Systems Constructed From 3M Company Interam Fire Barrier Material

11-14-1995

95-52

Supp-1

Fire Endurance Test Results for Electrical Raceway Fire Barrier

Systems Constructed from 3M Company Interam Fire Barrier Materials

 03-17-1998

96-23 Fires in Emergency Diesel Generator Exciters During Operation

Following Undetected Fuse Blowing

04-22-1996

96-33 Erroneous Data from Defective Thermocouple Results in a Fire. 05-24-1996

96-34 Hydrogen Gas Ignition During Closure Welding of a VSC-24

Multi-Assembly Sealed Baske

05-31-1996
Table D.4-5. NRC Information Notices Related to Fire Protection

IN Number Title Issue Date

D-14

97-01 Improper Electrical Grounding Results in Simultaneous Fires in the

Control Room and the Safe-Shutdown Equipment Room

01-08-1997

97-23 Evaluation and Reporting of Fires and Unplanned Chemical Reactor

Events at Fuel Cycle Facilities

05-07-1997

97-37 Main Transformer Fault with Ensuring Oil Spill into Turbine Building 06-20-1997

97-48 Inadequate or Inappropriate Interim Fire Protection Compensatory

Measures

07-09-1997

97-59 Fire Endurance Test Results of Versawrap Fire Barriers 08-01-1997

97-70 Potential Problems with Fire Barrier Penetration Seals 09-19-1997

97-72 Potential for Failure of the Omega Series Sprinkler Heads 09-22-1997

97-73 Fire Hazard in the Use of a Leak Sealant 09-23-1997

97-82 Inadvertent Control Room Halon Actuation Due to a Camera Flash 11-28-1997

98-31 Fire Protection System Design Deficiencies and Common-Mode

Flooding of Emergency Core Cooling System Rooms at Washington

Nuclear Project Unit 2

 08-18-1998

99-03 Exothermic Reactions Involving Dried Uranium Oxide Powder

(Yellowcake)

01-29-1999

99-05 Inadvertent Discharge of Carbon Dioxide Fire Protection System and

Gas Migration

03-08-1999

99-07 Failed Fire Protection Deluge Valves and Potential Testing Deficiencies

in Pre-Action Sprinkler Systems

03-22-1999

99-17 Problems Associated with Post-Fire Safe-Shutdown Circuit Analyses 06-03-1999

99-28 Recall of Star Brand Fire Protection Sprinkler Heads 09-30-1999

99-28

Supp-1

Recall of Star Brand Fire Protection Sprinkler Heads 03-22-2002

99-34 Potential Fire Hazard in the Use of Polyalphaolefin in Testing of Air

Filters

12-28-1999

00-12 Potential Degradation of Firefighter Primary Protective Garments 09-21-2000

00-14 Non-Vital Bus Fault Leads to Fire and Loss of Offsite Power 09-27-2000

01-04 Neglected Fire Extinguisher Maintenance Causes Fatality 04-11-2001

01-10 Failure of Central Sprinkler Company Model GB Series Fire Sprinkler

Head

06-28-2001

01-12 Hydrogen Fire at Nuclear Power Station 07-13-2001
Table D.4-5. NRC Information Notices Related to Fire Protection

IN Number Title Issue Date

D-15

01-12

(Errata)

Hydrogen Fire at Nuclear Power Station 08-08-2001

02-01 Metalclad Switchgear Failures and Consequent Losses of Offsite Power 01-08-2002

02-04 Wire Degradation at Breaker Cubicle Door Hinges 01-10-2002

02-07 Use of Sodium Hypochlorite for Cleaning Diesel Fuel Oil Supply Tanks 01-28-2002

02-15 Hydrogen Combustion Events in Foreign BWR Piping 04-12-2002

02-15

Supp. 1

Potential Hydrogen Combustion Events in BWR Piping 05-06-2003

02-24 Potential Problems With Heat Collectors on Fire Protection Sprinklers 07-19-2002

02-27 Recent Fires at Commercial Nuclear Power Plants in the United States 09-20-2002

03-19 Unanalyzed Condition of Reactor Coolant Pump Seal Leakoff Line

During Postulated Fire Scenarios or Station Blackout

10-06-2003
D-16

D.4.6 NRC Regulatory Issue Summaries Related to Fire Protection

A regulatory issue summary (RIS) is an informational document that is used to communicate with

the nuclear industry on a board spectrum have generic applicability. It dose not involve a request

for action or information unless it is stickily voluntary. Listed below are examples of way in which

a RIS may be used: 

• Document NRC endorsement of industry-developed resolutions to issues.

• Document NRC endorsement of industry guidance on technical or regulatory matters.

• Provide the status of staff interaction with the nuclear industry on a matter.

• Request the voluntary participation of licensees in staff-sponsored pilot programs.

• Inform licensees of opportunities for regulatory relief.

• Announce staff technical or policy positions on matters that have not been broadly

communicated to the nuclear industry or are not fully understood.

• Provide guidance to licensees on regulatory matters, such as the scope and detail of

information that should be provided in licensing applications to facilitate staff review.

• Announce the issuance and availability of regulatory documents [(topical reports, NUREGseries documents, and memoranda documenting the closeout of generic safety issues

(GSIs)].

• Request the voluntary submittal of information which will assist the NRC in the

administration of the regulatory process.

• Announce events of interest such as workshops and conferences.

• Announce changes in regulatory practices that could impact licensees.

• Announce changes in agency practices that could impact licensees.

Table D.4-6 provide the list of regulatory summaries related to fire protection.

Table D.4-6. NRCRegulatory Issue Summaries Related to Fire Protection

Regulatory

Issue Summary

Number

Title Issue Date

99-02 Relaxation of Technical Specification Requirements for Porc

Review of Fire Protection Program Changes

10-13-1999

01-09 Control of Hazard Barriers 04-02-2001

04-03 Risk-Informed Approach for Post-Fire Safe-Shutdown

Associated Circuit Inspections

03-02-2004

04-03, Rev. 1 Risk-Informed Approach for Post-Fire Safe-Shutdown

Associated Circuit Inspections

12-29-2004
D-17

D.5 Commission (SECY) Papers Related to Fire Protection

The primary decision-making tool of the Commission is the written issue paper submitted by the

Offices of the Executive Director for Operations (EDO), Chief Financial Officer (CFO), Chief

Information Officer (CIO), or other offices reporting directly to the Commission. Policy, rulemaking,

and adjudicatory matters, as well as general information, are provided to the Commission for

consideration in a document style and format established specifically for the purpose. Such

documents are referred to as “SECY Papers”. A SECY paper gains its nomenclature through the

designation (e.g., SECY-95-189) assigned to it by the Secretariat. Headings on the first page

designate whether the subject matter relates to the formulation of policy (Policy Issue papers), or

to the promulgation of agency rules (Rulemaking Issue papers), or to the granting, suspending,

revoking, or amending of licenses (Adjudicatory Issue paper). As described below, each paper also

indicates the type of action expected of the Commission:

• Commission Meeting Paper indicates a major issue on which collegial deliberation and vote

at a Commission meeting, usually in a public session, is anticipated.

• Notation Vote Paper indicates an issue requiring consideration by the Commission or

consultation with the Commission prior to action by the staff, but not requiring discussion

among Commissioners or a formal vote in a meeting.

• Affirmation Paper indicates Commission business that does not require discussion among

the Commissioners in a meeting mode, but by law must be voted by the Commissioners in

the presence of each other.

• Negative Consent Paper indicates a relatively minor action proposed to be taken by the staff

in the future. The Commission is authorized a period of time (usually 10 days) in which to

make its contrary views known; otherwise, SECY will advise the staff that the action

proposed in the paper may be taken.

• Information Paper provide information on policy, rulemaking, or adjudicatory issues.

As a general policy, SECY papers will be released to the public immediately after Commission

action is completed unless they contain specific, limited types of information which warrant

protection (adjudicatory, enforcement or investigatory, lawyer-client or legal work product, classified

or proprietary, and personal privacy information). Table D.5-1 provide the list of SECY papers

related to fire protection.
D-18

Table D.5-1. Commission (SECY) Papers Related to Fire Protection

SECY Title Issue Date

80-438A Commission Approval of the Final Rule on Fire Protection Program 09-30-1980

81-513 Plan for Early Resolution of Safety Issues 08-25-1991

82-267 Fire Protection Role for Future Plants 1982

83-133 Integrated Safety Assessment Program (ISAP) 03-23-1983

83-269 Memorandum from W. J. Dircks to the Commissioners, “Fire Protection

Role for Future Plants (SECY 82-267)”

07-1983

89-081 Final Report on Chernobyl Implications. 03-07-1989

89-170 Fire Risk Scoping Study: Summary of Results and Proposed Staff

Actions

06-07-1989

89-244 Training Symposium on Firearms and Explosives Recognition and

Detection

08-21-1989

90-16 Evolutionary Light-Water Reactor (LWR) Certification Issues and Their

Relationship to Current Regulatory Requirements

01-12-1990

91-283 Evaluation of Shutdown and Low Power Risk Issues 09-09-1991

92-263 Staff Plans for Elimination of Requirements Marginal to Safety 08-26-1992

93-049 Implementation of 10 CFR Part 45, Requirements for Renewal of

Operating Licenses for Nuclear Power Plants

03-01-1993

93-087 Policy, Technical, and Licensing Issues Pertaining to Evolutionary and

Advanced Light-Water Reactor (LWR) Designs

04-02-1993

93-143 NRC Staff Actions to Address the Recommendations in the Report on

the Reassessment of the NRC Fire Protection Program

05-21-1993

94-084 Policy and Technical Issues Associated with the Regulatory Treatment of

Non-Safety Systems in Passive Plant Design.

03-28-1994

94-090 Institutionalization of Continuing Program for Regulatory Improvement 03-31-1994

94-127 Options for Resolving the Thermo-Lag Fire Barrier Issue 05-12-1994

94-219 Proposed Agency-Wide Implementation Plan for Probabilistic Risk

Assessment (PRA)

08-19-1994

95-034 Status of Recommendations Resulting from the Reassessment of the

NRC Fire Protection Program

 02-13-1994

99-079 Status Update of the Agency-Wide Implementation Plan for Probabilistic

Risk Assessment

03-30-1995

96-134 Option for Pursuing Regulatory Improvement in Fire Protection

Regulations for Nuclear Power Plants

06-21-1996
Table D.5-1. Commission (SECY) Papers Related to Fire Protection

SECY Title Issue Date

D-19

96-162 Nuclear Power Plant-Specific Time-Temperature Curves for Testing and

Qualifying Fire Barriers

07-19, 1996

96-267 Fire Protection Functional Inspection Program 12-24-1996

97-127 Development of a Risk-Informed, Performance-Based Regulation 

for Fire Protection at Nuclear Power Plants

06-19-1997

97-278 Staff Requirements, Plans to Issue Confirmatory Orders Concerning

Schedules for Corrective Actions Regarding Licensee Use of ThermoLag 330-1 Fire Barriers

12-24-1997

97-287 Final Regulatory Guidance on Risk-Informing Regulations: Policy Issue 12-12-1997

98-058 Development of a Risk-Informed, Performance-Based Regulation for Fire

Protection at Nuclear Power Plants

03-26-1998

98-144 White Paper on Risk-Informed and Performance-Based Regulation 01-22-1998

98-161 The Westinghouse AP600 Standard Design as it Related to the Fire

Protection and the Spent Fuel Pool Cooling Systems.

07-01-1998

98-187 Interim Status Report - Fire Protection Functional Inspection Program 08-03-1998

98-230 Insights from NRC Research on Fire Protection and Related Issues 10-02-1998

98-247 Risk-Informed, Performance-Based Regulation for Fire Protection at

Nuclear Power Plants

10-27-1998

99-007 Recommendations for Reactor Oversight Process Improvements 01-08-1999

99-007A Recommendations for Reactor Oversight Process Improvements 03-22-1999

00-040 Second Interim Status Report - Fire Protection Functional Inspection

Program

02-05-1999

99-140 Recommendations for Reactor Fire Protection Inspections 05-20-1999

99-152 Status of Reactor Fire Protection Projects 06-07-1999

99-168 Improving Decommissioning Regulations for Nuclear Power Plants 06-30-1999

99-182 Assessment of the Impact of Appendix R Fire Protection Exemptions on

Fire Risk

 07-09-1999

99-183 Proposed Rule: Elimination of the Requirement for Noncombustible Fire

Barrier Seal Materials and Other Minor Changes (10 CFR Part 50)

07-14-1999

99-204 Kaowool and FP6-60 Fire Barriers 08-04-1999

00-0009 Rulemaking Plan, Reactor Fire Protection Risk-Informed, PerformanceBased Rulemaking01-13-2000
Table D.5-1. Commission (SECY) Papers Related to Fire Protection

SECY Title Issue Date

D-20

00-0055 Status Report on The Comprehensive Fire Protection Regulatory Guide

For Operating Reactors

03-02-2000

00-0080 Final Rule: Elimination of the Requirement for Noncombustible Fire

Barrier Penetration Seal Materials and Other Minor Changes 

04-10-2000

02-131 Update of the Risk-Informed Regulation Implementation Plan 02-12-2002

02-132 Proposed Rule: Revision of 10 CFR 50.48 to Permit Light-Water Reactors

to Voluntarily Adopt National Fire Protection Association (NFPA) Standard

805, “Performance-Based Standard for Fire Protection for Light-Water

Reactor Electric Generating Plants,” 2001 Edition (NFPA 805) as an

Alternative Set of Risk-Informed, Performance-Based Fire Protection

Requirements

 07-15-2002

03-0002 Evaluation of the Effects of the Baltimore Tunnel Fire on Rail Transportation

of Spent Nuclear Fuel

03-25-2003

03-0100 Rulemaking Plan on Post-Fire Operator Manual Actions 06-17-2003
D-21

D.6 NRC Preliminary Notifications Related to Fire Incidents

Preliminary Notifications issued by the Regions to inform the Commission and NRC staff of

incidents of interest occurring at NRC regulated facilities and some state regulated facilities. The

following fire incidents were last more than 10 minutes, and the reports are preliminary in nature.

Table D.5.1 provide the a list of preliminary notifications related to fire incidents.

Table D.6-1. Preliminary Notifications Related to Fire Incidents

PN Number Title Issue Date

29713 Turkey Point 3&4 - Electrical Fire 03-04-1997

19749 Haddam Neck - Control Room Evacuation Due To Halon Activation 08-08-1997

39780 Quad Cities 1, 2 - Fire Response Safe Shutdown Procedure

Deficiencies

09-29-1997

49764 General Atomics - Fire in Hot Cell Undergoing Decommissioning 11-03-1997

39799 Quad Cities 1 - Unit 1 Shut Down Because Appendix R (Fire) Safe

Shutdown Analysis Not Completed

12-23-1997

29816 General Electric Company - Fire In Dumpster 03-17-1998 

29818 GTS Duratek - Bag House Fire 03-25-1998

29820 Kenton Meadows Company, Inc. - Gauge Involved In Building Fire 03-30-1998

49817 Siemens Nuclear Power Corporation - Fire in Waste Handling Area 04-15-1998

49817a Siemens Nuclear Power Corporation - Fire in Waste Handling Area

(Update)

04-16-1998

29831 Turkey Point - Notice of Unusual Event Due to Fire on Site Lasting

More than 10 Minutes

06-10-1998

49826 Washington Nuclear 2 - Internal Flooding Caused by Fire Header Line

Valve Rupture

06-18-1998

49826a Washington Nuclear 2 - Update to Internal Flooding Caused by Fire

Water System Valve Rupture and Arrival of Augmented Inspection

Team

06-19-1998

49826b Washington Nuclear 2 - AIT Activities for Internal Flooding Caused by

Fire Water System Valve Rupture and Termination of NOUE

06-23-1998

29833 Schlumberger Technology - Well Fire Involving 40 Millicurie Cesium

137 Source

07-02-1998 

29833a Schlumberger Technology - Well Fire Involving 40 Millicurie Cesium

137 Source (Update)

07-07-98

39844 Department of the Army - Tritium Contamination Event (Broken Fire

Control Devices)

09-14-1998 
Table D.6-1. Preliminary Notifications Related to Fire Incidents

PN Number Title Issue Date

D-22

19849 Safety Light Corporation - Fire in Building on Safety Light Corporation 10-19-1998

Site

19849a Safety Light Corporation - Fire in Building on Safety Light Corporation

Site (Update) 

10/21/1998

39848 Fermi 2 - Decl. of Alert Cond. Due to Fire in Emerg. Diesel Gen.

Control Panel

10-21-1998

39858 Portsmouth Gaseous Diffusion Plant - Fire in Process Building 12-09-1998

39858a Portsmouth Gaseous Diffusion Plant - Fire in Process Building- Update 12/15/1998

39901 Prairie Island 1 - Station Auxiliary Transformer Explosion and Fire 01-06/1999

39858b Portsmouth Gaseous Diffusion Plant - Fire in Process Building -

Second Update

01-13-1999

19903 Fitz Patrick - Notification of Unusual Event Due to a Fire at an Onsite

Hydrogen Storage Facility

01-15-1999

19904 Millstone 3 - Carbon Dioxide Discharge Into Cable Spreading Room 01-20-1999

19926 Pilgrim 1 - Main Transformer Fire - Media Interes 05-19-1999

39931 Palisades 1 - Minor Hydrogen Burns During Cask Welding Activities 06-10-1999

39932 Palisades 1 - Dry Cask Storage Project Office Damaged by Fire 06-18-1999

39945 Allied Signal, Inc. - Brush Fire on Site Property One-Fourth Mile From

Plant

10-01-1999

19946 Nine Mile Point 1 - Unusual Event Declaration Due to Carbon Dioxide

Discharge in Administration Building

10-8-1999

29950a Fairfax County Government - Fixed Gauge Damaged in a Fire 12-27-1999

400011 Unusual Event Because of a Fire Lasting Greater than 15 Minutes 05-152-00

400011a Update - Unusual Event Because of a Fire Lasting Greater Than 15

Minutes

05-16-2000

400011b Unusual Event Because of a Fire Lasting Greater Than 15 Minutes 05-26-2000

400016 Range Fire Nearby NRC Licensed Facilities (Siemens Power

Corporation and WNP-2)

06-30-2000

200031 Alert Declared by Farley Due to Fire and Trip of the 2C Service Water

Pump

08-17-2000

200039 Fire in B Main Power Transformer 09-22-2000

401001 Accidental Fire Damages Three Portable Gauges 01-05-2001
Table D.6-1. Preliminary Notifications Related to Fire Incidents

PN Number Title Issue Date

D-23

201002 Incinerator Fire 01-6-2001

401004 Circuit Breaker Failure and Fire, Resulting in Reactor Shutdown 2-06-2001

301010 Alert Declared Due to Small Fire on an Emergency Diesel Generator

Bearing Cover

03-22-2001

401025 Fire Affecting The Startup Transformer at Cooper Nuclear Station 06-25-2001

401024 Switchyard Fire Caused by the Failure of the Phase a Bus Potential

Transformer.

06-25-2001

301027 Electrical Panel Fire During Plant Startup 08-06-2001

301029 Fixed Gauges Damaged in Fire 08-29-2001

301036 Potential Small Fire Event 11-06-2001

302025 Fire in D.C. Cook Unit 1 Switchyard 06-12-2002

302025A Fire in D.C. Cook Unit 1 Switchyard (Update) 06-13-2002

302028 Fire at Decommissioned Westinghouse-Hematite Uranium Fuel

Fabrication Facility

06-20-2002

302028A Fire at Decommissioned Westinghouse-Hematite Uranium Fuel

Fabrication Facility (Update)

06-21-2002

202031 Fire Trip of 1C Service Water Pump 08-21-2002

202032 Notification of Unusual Event (NOUN) Due to Fire in the Turbine

Building - McGuire (Event Number 39145)

08-23-2002

202036 Unusual Event Declared, Fire in Control Building at Watts Bar Unit 1,

Hydro Plant

09-26-2002

202036A Unusual Event Declared, Fire in Control Building at Watts Bar Unit 1,

Hydro Plant

09-30-2002

303014 Unusual Event Declared Due to Fire in the Main Turbine 04-29-2003
D-24

D.7 NRC Miscellaneous Documents Related to Fire Protection

“Operating Experience Assessment, Energetic Faults in 4.16 kV to 13.8 kV Switchgear and Bus

Ducts That Caused Fire in Nuclear Power Plants 1986-2001,” Office of Nuclear Regulatory

Research, U.S. Nuclear Regulatory Commission, Washington, DC, February 2002 (ADAMS

Accession #ML021290358).

RES/OERAB/S02-01, Vol.1, “Fire Events - Update of U.S. Operating Experience, 1986-1999,

Commercial Power Reactors,” Division of Risk Analysis and Applications, Office of Nuclear

Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC, January 2002

(ADAMS Accession #020360172) and (ADAMS Accession #ML020450056).

AEOD/S97-03, “Special Study: Fire Events - Feedback of U.S. Operating Experience,” U.S. Nuclear

Regulatory Commission, Office for Analysis and Evaluation of Operational Experience, June 1997.

“Fire Protection Barriers to Effective Implementation of NRC’s Safety Oversight Process,” U.S.

Nuclear Regulatory Commission Washington, DC, Report to the Honorable Edward J. Markey,

House of Representatives, GAO/REED-0039, U.S. General Accounting Office, Washington, DC,

April 2000 (ADAMS Accession #ML003718163).

“Circuit Analysis-Failure Mode and Likelihood Analysis,” A Letter Report to USNRC, Sandia

National Laboratory, Albuquerque, New Mexico, ADAMS Accession # ML010450362, May 8, 2000.

(This letter report is available through the NRC’s Public Document Room under a NRC cover

memorandum from T.L. King, NRC/RES/DRAA, to G.M. Holahan, NRC/NRR/DSSA, and M.E.

Mayfield, NRC/RES/DET, dated June 13, 2000.)

“A Evaluation of the Fire Barrier System Thermo-Lag 330-1,” SANDIA 94-0146, Sandia National

Laboratories (SNL), Albuqerque, New Mexico, September 1994.

NRC Inspection Manual, Part 9900 (IM STS-10) - Technical Guidelines, Standard Technical

Specification, Section 1.0 - Operability, p. 31, 1986.

NRC Inspection Manual, Chapter 0609, Appendix F, “Determining Potential Risk Significance of

Fire Protection and Post-Fire Safe Shutdown Inspection Findings”, February 27, 2001.

Inspection Procedure 64100, (IP 64100) - Postfire Safe Shutdown Emergency Lighting and Oil

Collection Capability at Operating and Near-term Operating Reactor Facilities.

Inspection Procedure 64150, (IP 64150) - Triennial Postfire Safe Shutdown Capability.

Inspection Procedure 64704, (IP 64704) - Fire Protection Program, June 24, 1998.

Inspection Procedure 71111.05, (IP 71111.05) - Fire Protection, April 3, 2000.

Temporary Instruction 2515/62 (TI 2515/62) - Post Fire Safe Shutdown Emergency Lighting and

Oil Collection Capability at All Operating Plants, Revision 2, February 14, 1985.
D-25

Temporary Instruction 2515/XX (TI 2515/XX) - Fire Protection Functional Inspection.

NRR Office Instruction, “NRR Interface With the Office of the General Counsel”, September 11,

2002 (ADAMS Accession #ML020910237).

Memorandum for Z. Rosztoczy from S. Bajwa, “Generic Issue 148: Smoke Control and Manual Fire

Fighting Effectiveness; Generic Issue 149: Adequacy of Fire Barriers,” April 3, 1991.

Letter to D. Basdekas (NRC) from L. Lambright (SNL), “Generic Issue 1480: Smoke Control and

Manual Fire Fighting Effectiveness,” March 4, 1992.

Memorandum for W. Minners from E. Beckjord, “Generic Issue 148: Smoke Control and Manual

Fire Fighting Effectiveness; Generic Issue 149: Adequacy of Fire Barriers,” August 26, 1992.

Memorandum from T. King to A. Thadani, “Staff Review Guidance for Generic Issue (GSI) 148:

Smoke Control and Manual Fire Fighting Effectiveness; Generic Issue 149: Adequacy of Fire

Barriers,” July 22, 1992.

Memorandum dated July 22 1999, from Thomas L. King, Office of Nuclear Regulatory Research,

NRC, to Ashok C. Thadani, Office of Nuclear Regulatory Research, NRC, Subject: Staff Review

Guidance for Generic Safety Issue (GSI) 148, “Smoke Control and Manual Fire-Fighting

Effectiveness.”

Letter dated November 12, 1999, from Dana A. Powers, Chairman ACRS, NRC, to Dr. William D.

Travers, Executive Director of Operations, NRC, Subject: Proposed Resolution of Generic Safety

Issue (GSI)-148, “Smoke Control and Manual Fire-Fighting Effectiveness.”

Letter dated December 15, 1999, from William D. Travers, Executive Director of Operations, NRC,

to Dana A. Powers, Chairman ACRS, NRC, Subject: Resolution of Generic Safety Issue (GSI)-148,

“Smoke Control and Manual Fire-Fighting Effectiveness.”

NRC Letter to All Licensees Holding Operating Licenses and Construction Permits for Nuclear

Power Reactor Facilities, “Individual Plant Examination for Severe Accident Vulnerabilities - 10 CFR

§ 50.54(f), (Generic Letter 88-20),” November 23, 1988, (Supplement 1) August 29, 1989,

(Supplement 2) April 4, 1990, (Supplement 3) July 65, 1990, (Supplement 4) June 28, 1991. 

ZAR-791030-01, “Report of the President’s Commission on the Accident at Three Mile Island,” J

G. Kemeny, et al., November 30, 1979.

Memorandum for E. Beckjord from J. Murphy, “Staff Review Guidance for Generic Safety Issue

(GSI) 147, Fire-Induced Alternate Shutdown/Control Room Panel Interactions,” March 9, 1994.

Memorandum for W. Russell from T. Murley, “Final Report-Special Review Team for the Review

of Thermo-lag Fire Barrier Performance,” April 21, 1992.

Memorandum to Dr. Dana A. Powers, Chairman Fire Protection Subcommittee from, A. Singh,

“Proposed Resolution of Generic Safety Issue 148, Smoke Control and Manual Fire-Fighting

Effectiveness,” September 17, 1999.
D-26

Koski, J.A., J.G. Bobbe, M. Arviso, S.D. Wix, D.E. Beene, R. Byrd, and J. Graupmann,

“Experimantal Determination of the Shipboard Fire Environment for Simulated Radioactive Material

Packages,” SAND 97-0606, Sandia National Laboratories, Albuquerque, New Mexico, 1997.

Dey, M., A. Hamins, and M. Steward, “International Collaborative Project to Evaluate Fire Models

for Nuclear Power Plant Applications: Summary of 5 Meeting,” NISTIR 6986, National Institute of th

Standards and Technology, Gaithersburg, Maryland, September 2003. 
D-27

D.8 NRR Staff Presentations and Publications Related to Fire Protection

Connell, E.A., “Individual Plant Examination of External Events Program: Perspectives on The Fire

Risk Assessment of Operating Reactors,” Second International Conference on Fire Research and

Engineering on August 12, 1997, at the National Institute of Standards and Technology (NIST) in

Gaithersburg, Maryland.

Connell, E.A., “Fire PRA Needs—Regulators Perspective,” Proceedings from International

Workshop on Fire Risk Assessment, Organized by the Nuclear Energy Agency (NEA), Committee

on the Safety of Nuclear Installation (CSNI) Helsinki, Finland, 29 June–2 July 1999,

NEA/CSNI/R(99)26.

Iqbal, N., and M.H. Salley, “Development of a Quantitative Fire Scenario Estimating Tool for the

U.S. Nuclear Regulatory Commission Fire Protection Inspection Program,” Structural Mechanics

in Reactor Technology (SMiRT) Post-Conference Fire Protection Seminar No. 1, August 20-23,

2001, at the Millstone Nuclear Power Station Conference Facility in Waterford, Connecticut.

Iqbal, N., and M.H. Salley, “First Applications of a Quantitative Fire Hazard Analysis Tool for

Inspection in the U.S. Commercial Nuclear Power Plants,” 5 Meeting, International Collaborative th

Project to Evaluate Fire Models for Nuclear Power Plants Applications, Building and Fire Research

Laboratory (BFRL), National Institute of Standards and Technology (NIST), Gaithersburg, Maryland,

May 2–3, 2002. 

Madden, P.M., “Defense-In-Depth: A Regulatory Approach for Assuring Post-Fire Safe-Shutdown

Capability,” Proceedings, Specialist Meeting on Fire Protection and Fire Protection Systems in

Nuclear Power Plants, Committee on the Safety of Nuclear Installation (CSNI), Organization for

Economic Co-Operation and Development (OECD), Cologne, Germany, 6–9 December 1993.

Madden, P.M., “Assessment of Postulated Fires Resulting From Turbine Failures and Their

Mitigation at U.S. Nuclear Power Facilities,” Fire Safety 1994 Conference, Barcelona, Spain.

Madden, P.M., “Fire Safety Rulemaking Issues Confronting Regulatory Change in the United

States,” Structural Mechanics in Reactor Technology (SmiRT) 14, Fifth Post Conference Seminar

No. 6, Fire Safety in Nuclear Power Plants and Installations,” August 25–28, 1997, Lyon, France.

Notley, D.P., “Fire Protection in Nuclear Power Plants - Understanding Competing Requirements

for Safety,” Proceedings of an International Symposium on Fire Protection and Fire Fighting in

Nuclear Installation, Organized by the International Atomic Energy Agency (IAEA) Vienna, Austria,

27 February to 3 March 1989, pp. 53–63.

Salley, M.H, “Tests to Develop Corrective Measures For Electrical Raceway Fire Barrier Systems:

Part 1 “Ten Rules of Fire Endurance Testing,” The Society of Fire Protection Engineers (SFPE)

Technical Symposium on Application of Fire Testing in Fire Protection Engineering Practice, March

12–13, 1998, Hyatt Fair Lakes Hotel, Fairfax, Virginia

Salley, M.H, “Perspectives on the Implementation of Fire Protection Risk-Informed,

Performance-Based Regulations in the United States Nuclear Power Industry,” NFPA World Fire

Safety Congress and Exposition, Baltimore, Maryland, May 19, 1999.
D-28

D.9 NRC Technical Reports in the NUREG Series Related to Nuclear Power

Plant Fire Protection Engineering Research and Development (R&D)

The NRC publishes a variety of technical and regulatory reports, normally issued as NUREGs

[NUREG is the NRC technical report designation (NUclear REGulatory Commission)].

The NRC publishes the following types of documents in its NUREG-series: reports, including those

prepared for international agreements, which cover a variety of regulatory, technical, and

administrative subjects; brochures, which usually include directories, manuals, procedural guidance

and newsletters and are often intended primarily for internal use; conference proceedings, a

compilation of papers that have been presented at a conference or workshop; and books, which

serve a unique technical purpose or an industry-wide need. Each NRC publication has a unique

alphanumeric designator beginning with the alpha designator NUREG, followed by either a

four-digit number or by two letters further identifying the type of report and a four-digit number, as

follows: 

NUREGs NRC staff reports or books prepared by the NRC staff

NUREG/BRs NRC brochures prepared by the NRC staff

NUREG/CRs NRC contractor reports prepared for the NRC by a contractor

NUREG/CPs NRC conference proceedings prepared by either the NRC staff or a contractor

NUREG/GRs NRC grantee reports prepared with the support of the NRC grant program 

NUREG/IAs International agreement reports resulting from an international agreement and

usually overseen by the NRC staff

NUREG/TRs Translation reports translated for the NRC

Availability Information

Copies of NUREG-series documents may be obtained from the following source:

Reproduction & Distribution Services Branch

Web, Publishing, and Distribution Services Division

Office of the Chief Information Officer

U.S. Nuclear Regulatory Commission

Mail Stop OWFN P1-33

Washington, DC 20555-0001

Email: DISTRIBUTION@nrc.gov

Facsimile: (301) 415-2289
D-29

Many NRC documents are available electronically in our Reference Library on our Web site,

www.nrc.gov, and through our Electronic Reading Room (ADAMS, or PARS, document system)

at the same site. Copies of NUREGS and many other NRC documents are available for inspection

or copying for a fee from the NRC Public Document Room (PDR) at:

U.S. Nuclear Regulatory Commission

Public Document Room

11555 Rockville Pike

Rockville, Maryland 20852

PDR’s mailing address is:

U.S. Nuclear Regulatory Commission

Public Document Room

11555 Rockville Pike

Washington, DC 20555-0001

Phone (301) 415 - 4737 or (800) 397 - 4209

Facsimile (301) 415 - 3548

E-mail pdr@nrc.gov.

Copies of NUREG-series reports are available at current rates from the:

Superintendent of Documents

U.S. Government Printing Office

Mail Stop SSOP

Washington, DC 20402-0001

Email: bookstore@gpo.gov

Phone: (202) 512-1800

Facsimile: (202) 512-2250

Also, copies of NUREG-series reports are available from the:

National Technical Information Services (NTIS)

U.S. Department of Commerce

Technology Administration

5285 Port Royal Road

Springfield, Virginia 22161

Phone: (800) 553-6847 or (703) 605-6000

Internet: http://www.ntis.gov
D-30

The following is a list of NUREG-series reports related to fire protection:

NUREG-75/014, WASH-1400, “Reactor Safety Study: An Assessment of Accident Risks in U.S.

Commercial Nuclear Power Plants,” October 1975.

NUREG-75/087, “Standard Review Plan for the Review of Safety Analysis Reports for Nuclear

Power Plants,” LWR Edition, Interim Report, September 1975. 

NUREG-75/087 (A11), “Standard Review Plan for the Review of Safety Analysis Reports for

Nuclear Power Plants,” LWR Edition, Interim Report, September 1975. 

NUREG-75/087-CH2, “Standard Review Plan,” Chapter 2, November 24, 1975. 

NUREG-0050, “Recommendations Related to Browns Ferry Fire,” Report by Special Review Group,

February 1976.

NUREG/TR-0018, “Review of Literature on Vapor Explosion: First Technical Report on Research

Project BMFT - RS 76”, February 1976.

NUREG-0061, “Operation of Browns Ferry, Units 1 and 2 Following the March 22, 1975 Fire,”

Safety Evaluation Report, March 1976.

NUREG-0061-Suppl-1, Operation of Browns Ferry, Units 1 and 2 Following the March 22, 1975

Fire,” Safety Evaluation Report, Supplement 1, 18 June, 1976.

NUREG-766516, “Report on Task I - Fire Protection System Study,” February 1977.

NUREG/CR-0075, “Accidental Vapor Phase Explosion on Transportation Routes Near Nuclear

Power Plant,” April 1977.

NUREG-0206, “Progress Report on Fire Protection Research,” June 1977.

BNL-NUREG-23316, “Turbine Oil Fires as Related to Nuclear Power Stations,” September 1977.

BNL-NUREG-23364, “Fire Damage Data Analysis as Related to Current Testing Practices for

Nuclear Power Application,” October 1977.

BNL-NUREG-23392, “Design Base Fires in Nuclear Power Plants,” October 1977.

NUREG-0298 (Vol.1) (No.1), “Fire Protection Action Plan: Status Summary Report,” 13 February,

1978.

NUREG/CR-0366, “Fire Protection Research Quarterly Progress Report (October - December

1977),” March 8, 1978.

BNL-NUREG-23910, “Fire Scenarios in Nuclear Power Plant,”1978.
D-31

NUREG/CR-0152, “Development and Verification of Fire Tests for Cable Systems and System

Components,” June 1978.

NUREG-0298 (Vol.1) (No.3), “Fire Protection Action Plan, Status Summary Report, Data for

Decisions, Management by Objectives,” 28 August, 1978.

NUREG/CR-0403, “High Temperature Testing of Smoke Detector Sources,” September 1978.

NUREG/CR-0346, “Development and Verification of Fire Tests for Cable Systems and System

Components,” September 1978.

NUREG/CR-0381, “A Preliminary Report on Fire Protection Research Program Fire Barriers and

Fire Retardant Coatings Tests”, September 1978. 

NUREG/CR-0376, “Models of Horizontal Electrical Cables and Cable Trays Exposed to a Fire

Plume,” September 1978.

BNL-NUREG-25101, “Performance of Fire Protection Systems Under Post Earthquake Conditions,”

October 1978.

NUREG/CR-0596, “Preliminary Report on Fire Protection Research Program Fire Barriers and

Suppression (September 15, 1978, Test),” December 1978. 

NUREG-0298 (Vol.1)(No.4), “Fire Protection Action Plan, Status Summary Report, Data for

Decisions, Management by Objectives,” December 1978. 

NUREG/CR-0488, “Nuclear Power Plant Fire Protection-Fire Detection,” (Subsystems Study Task 2),

March 1979.

NUREG/CR-0636, “Nuclear Power Plant Fire Protection-Ventilation,” (Subsystems Study Task 1),

August 1979.

NUREG/CR-0468, “Nuclear Power Plant Fire Protection-Fire Barriers,” (Subsystems Study Task 3),

September 1979.

NUREG/CR-0654, “Nuclear Power Plant Fire Protection Fire-Hazard Analysis (Subsystems Study

Task 4),” September 1979.

NUREG-0585, “TMI Lessons Learned Task Force Final Report,” October 1979.

NUREG/CR-1156, “Environmental Assessment of Ionization Chamber Smoke Detectors Containing

Am-241,” November 1979.

NUREG/CR-0833, “Fire Protection Research Program Corner Effects Tests,” December 1979.

NUREG-0654, “Criteria for Preparation and Evaluation of Radiological Emergency Response Plans

and Preparedness in Support of Nuclear Power Plants,” Interim Report, January 1980.
D-32

NUREG/CR-1405, “NACOM Code for Analysis of Postulated Sodium Spray Fires in LMFBRs,”

March 1980.

NUREG/CR-1798, “Acceptance and Verification for Early Warning Fire Detection Systems,” Interim

Guide, May 1980.

NUREG/CR-1184, “Evaluation of Simulator Adequacy for the Radiation Qualification of

Safety-Related Equipment,” May 1980.

NUREG/CR-2269, “Probabilistic Models for the Behavior of Compartment Fires,” August 1980.

NUREG/CR-1552, “Development and Verification of Fire Tests for Cable Systems and System

Components,” September 1980. 

NUREG/CR-1614, “Approaches to Acceptable Risk: A Critical Guide,” September 1980.

NUREG/CR-1819, “Development and Testing of a Model for Fire Potential in Nuclear Power

Plants,” November 1980.

NUREG/CR-1741, “Models for the Estimation of Incapacitation Times Following Exposures to Toxic

Gases or Vapors,” December 1980.

NUREG-0492, “Fault Tree Handbook,” January 1981.

NUREG/CR-1682, “Electrical Insulators in a Reactor Accident Environment,” January 1981.

NUREG/CR-1930, “Index of Risk Exposure and Risk Acceptance Criteria,” February 1981.

NUREG/CR-1916, “A Risk Comparison,” February 1981.

NUREG/CR-1748, “Hazards to Nuclear Power Plants from Nearby Accidents Involving Hazardous

Materials-A Preliminary Assessment,” April 1981.

NUREG/CP-0018, Proceedings of the Workshop on Frameworks for Developing a Safety Goal,

Palo Alto, California, April 1-3, 1981.

NUREG/CR-2079, “Analysis of Credible Accidents for Argonaut Reactors, Report for October

1980-April 1981,” April 1981. 

NUREG/CR-2040, “Study of the Implications of Applying Quantitative Risk Criteria in the Licensing

of Nuclear Power Plants in the United States,” May 1981.

NUREG/CR-2269, “Probabilistic Models for the Behavior of Compartment Fires,” August 1981.

NUREG/CR-2017-Volume IV of IV, “Halon Inerting as a Hydrogen Control Measure for Sequoyah,”

Proceedings of the Workshop on the Impact of Hydrogen on Water Reactor Safety, Edited by M.

Berman, September 1981.
D-33

NUREG/CR-2258, “Fire Risk Analysis for Nuclear Power Plants,” September 1981.

NUREG/CR-2017-Volume 3, “Flammability Limits and Pressure Development in Hydrogen-Air

Mixtures,” Proceedings of the Workshop on the Impact of Hydrogen on Water Reactor Safety,

September 1981.

NUREG/CR-2017-Volume 4, “Halon 1301 Protection System for Nuclear Containment,”

Proceedings of the Workshop on the Impact of Hydrogen on Water Reactor Safety, September

1981.

NUREG/CR-2321, “Investigation of Fire Stop Test Parameters,” Final Report, September 1981.

NUREG/CR-2377, “Tests and Criteria for Fire Protection of Cable Penetrations,” October 1981.

NUREG/CR-2490, “Hazards to Nuclear Power Plants From Large Liquefied Natural Gas (LNG)

Spills on Water,” November 1981. 

NUREG/CR-2431, “Burn Mode Analysis of Horizontal Cable Tray Fires,” February 1982.

NUREG/CR-2486, “Final Results of the Hydrogen Igniter Experimental Program,” February 1982.

NUREG/CR-3214, “Aging with Respect to Flammability and Other Properties in Fire-Retarded

Ethylene Propylene Rubber and Chlorosulfonated Polyethylene,” March 1982.

NUREG/CR-2409, “Requirements for Establishing Detector Siting Criteria in Fires Involving

Electrical Materials,”July 1982.

NUREG/CR-2868, “Aging Effects on Fire-Retardant Additives in Organic Materials for Nuclear Plant

Applications,” August 1982.

NUREG/CR-2730, “Hydrogen Burn Survival: Preliminary Thermal Model and Test Results,” August

1982.

NUREG/CR-2927, “Nuclear Power Plant Electrical Cable Damageability Experiments,” October

1982.

NUREG/CR-2650, “Allowable Shipment Frequencies for the Transport of Toxic Gases Near Nuclear

Power Plants,” October 1982.

NUREG/CR-2859, “Evaluation of Aircraft Crash Hazards for Nuclear Power Plants,” 1982.

NUREG/CR-2300, “PRA Procedures Guide - A Guide to the Performance of Probabilistic Risk

Assessments for Nuclear Power Plants,” Volume 1 and 2 January 1983.

NUREG/CR-2607, “Fire Protection Research Program for the U.S. Nuclear Regulatory Commission

1975-1981,” April 1983.

NUREG/CR-3239, “COMPBRN-A Computer Code for Modeling Compartment Fires,” May 1983.
D-34

NUREG/CR-2475, “Hydrogen Combustion Characteristics Related to Reactor Accidents,”

July 1983.

NUREG/CR-2658, “Characteristics of Combustion Products: A Review of the Literature,” July 1983.

NUREH/CR-3385, “Measures of Risk Importance and Their Application,” July 1983. 

NUREG/CR-3122, “Potentially Damaging Failure Modes of High-and Medium-Voltage Electrical

Equipment,” July 1983.

NUREG/CR-3330, “Vulnerability of Nuclear Power Plant Structures to Large External Fires,”

August 1983.

NUREG/CR-2726, “Light Water Reactor Hydrogen Manual,” August 1983.

NUREG/CR-2462, “Capacity of Nuclear Power Plant Structure to Resist Blast Loading,”

September 1983.

NUREG/CR-3192, “Investigation of Twenty-Foot Separation Distance as a Fire Protection Method

as Specified in 10 CFR 50, Appendix R,” October 1983.

NUREG/CR-3242, “Los Alamos National Laboratory/New Mexico State University Filter Plugging

Test Facility: Description and Preliminary Test Results” October 1983.

NUREG/CR-3527, “Material Transport Analysis for Accident-Induced Flow In Nuclear Facilities,”

October 1983.

NUREG/CR-3541, “Measures of the Risk Impacts of Testing and Maintenance Activities,”

November 1983. 

NUREG/CR-3527, “Material Transport Analysis for Accident-Induced Flow in Nuclear Facilities,”

December 1983.

NUREG/CR-3548, “Hazardous Materials Accidents Near Nuclear Power Plants: An Evaluation of

Analyses and Approaches,” 1983.

NUREG/CR-2462, “Capacity of Nuclear Power Plant Structures to Resist Blast Loading,” 1983.

NUREG/BR-0075, “NRC Field Policy Manual,” January 1984.

NUREG-0800, “Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power

Plants, April 1984.

NUREG/CR-3735, “Accident-Induced Flow and Material Transport in Nuclear Facilities: A Literature

Review,” April 1984.

NUREG/CR-3139, “Scenarios and Analytical Methods for UF Releases at NRC-licensed Fuel Cycle

Facilities,” June 1984. 
D-35

NUREG-0675, Supplement 23, “Safety Evaluation Report Related to the Operation of Diablo

Canyon Nuclear Power Plant, Units 1 and 2,” June 1984.

NUREG-0681, Supplement 4, “Safety Evaluation Report Related to the Operation of South Texas

Project, Unit 1 and 2,” July 1984.

NUREG/CR-3493, “Review of the Limerick Generating Station Severe Accident Risk Assessment -

Review of Core-Melt Frequency,” July 1984.

NUREG/CR-3521, “Hydrogen-Burn Survival Experiments at Fully Instrumented Test Site (FITS),”

August 1984.

NUREG/CR-3719, “Detonation Calculations Using a Modified Version of CSQΙΙ: Examples for

Hydrogen-Air Mixtures,” August 1984.

NUREG/CR-3922, “Survey and Evaluation of System Interaction Events and Sources,” Appendices

A and B, Volume 1, January 1985.

NUREG/CR-3922, “Survey and Evaluation of System Interaction Events and Sources,” Appendices

C and D, Volume 2, January 1985.

NUREG/CR-4479, “Use of a Field Model to Assess Fire Behavior in Complex Nuclear Power Plant

Enclosures: Present Capabilities and Future Prospects,” January 1985.

NUREG/ CR-4112-Volume 1, “Investigation of Cable and Cable System Fire Test Parameters,

Volume 1, Task A: IEEE 383 Flame Test,” January 1985.

NUREG/CR-4112-Volume 2, “Investigation of Cable and Cable System Fire Test Parameters,

Volume 2, Task B: Firestop Test Method,” January 1985.

NUREG/CR-3638, “Hydrogen-Steam Jet-Flame Facility and Experiments,” February 1985.

NUREG/CR-4230, “Probability-Based Evaluation of Selected Fire Protection Features in Nuclear

Power Plants,” May 1985.

NUREG/CR-4264, “Investigation of High-efficiency Particulate Air Filter Plugging by Combustion

Aerosols,” May 1985. 

NUREG/CR-4231, “Evaluation of Available Data for Probabilistic Risk Assessments (PRA) of Fire

Events at Nuclear Power Plants,” May 1985.

NUREG/CR-4229, “Evaluation of Current Methodology Employed in Probabilistic Risk Assessment

(PRA) of Fire Events at Nuclear Power Plants,” May 1985.

NUREG-1148, “Nuclear Power Plant Fire Protection Research Program,” July 1985.

NUREG/CR-4321, “Full-scale Measurements of Smoke Transport and Deposition in Ventilation

System Ductwork, July 1985.
D-36

NUREG/CR-2815, “Probabilistic Safety Assessment Procedures Guide,” August 1985.

BNL-NUREG-36946, “Use of a Field Model to Analyze Probable Fire Environments Encountered

Within the Complex Geometries of Nuclear Power Plants,” August 1985.

BNL-NUREG-36873, “Probabilistic Analysis of Fires in Nuclear Plants,” 1985.

NUREG/CR-4310, “Investigation of Potential Fire-Related Damage to Safety-Related Equipment

in Nuclear Power Plants,” November 1985.

NUREG/CR-4138, “Data Analysis for Nevada Test Site (NTS) Premixed Combustion Tests,” May,

1985.

NUREG/CR-4136, “SMOKE: A Data Reduction Package for Analysis of Combustion Experiments,”

September 1985.

NUREG/CR-4561, “FIRAC User’s Manual: A Computer Code to Simulate Fire Accidents in Nuclear

Facilities,” April 1986.

NUREG/CR-4330-Vol.1, “Review of Light Water Reactor Regulatory Requirements: Identifications

of Regulatory Requirements That May Have Marginal Importance to Risk,” Volume 1, April 1986.

NUREG/CR-4330-Vol.2, “Review of Light Water Reactor Regulatory Requirements: Identifications

of Regulatory Requirements That May Have Marginal Importance to Risk,” Volume 2, June 1986.

NUREG/CR-4596, “Screening Tests Representative Nuclear Power Plant Components Exposed

to Secondary Environments Created by Fires,” June 1986.

NUREG/CR-4570, “Description and Testing of an Apparatus for Electrically Initiating Fires Through

Simulation of a Faulty Connection,” June 1986.

NUREG/CR-4566, “COMPBRN III - A Computer Code for Modeling Compartment Fires,” July 1986.

NUREG/CR-4586, “User Guide for a Personnel-Computer-Based Nuclear Power Plant Fire Data

Base,” August 1986.

NUREG/CR-4638/1of 2, “Transient Fire Environment Cable Damageability Test Results: Phase ,”

September 1986.

NUREG/CR-3656, “Evaluation of Suppression Methods for Electrical Cables Fires,” October, 1986.

NUREG/CR-4680, “Heat and Mass Release for Some Transient Fuel Sources Fires: A Test

Report,” October 1986.

NUREG/CR-3468, “Hydrogen-Air-Steam Flammability Limits and Combustion Characteristics in the

FITS Vessel,” December 1986.
D-37

BNL-NUREG-38839, “Fire Environment Determination in the LaSalle NPP Control Room,” 1986.

NUREG 2/CR-4905, “Detonability of H -Air-Diluent Mixtures,” 1986.

NUREG-1250, “Report on the Accident at the Chernobyl Nuclear Power Station,” January 1987.

NUREG/CR-4679, “Quantitative Data on the Fire Behavior of Combustible Materials Found in

Nuclear Power Plants: A Literature Review,” February 1987.

NUREG/CR-4829, “Shipping Container Response to Severe Highway and Railway Accident

Condition,” February 1987.

NUREG/CR-4681, “Enclosure Environment Characterization Testing for Base Line Validation of

Computer Fire Simulation Codes,” March 1987.

NUREG/CR-4736, “Combustion Aerosols Formed During Burning of Radioactively Contaminated

Materials, Experimental Results,” March 1987.

NUREG/CR-4830, “MELCOR 1.0 and HECTR 1.5 Calculations for Browns Ferry Reactor Building

Burns, MELCOR Validation and Verification: 1986 Papers,” March 1987.

NUREG/CR-4527/1 of 2, “An Experimental Investigation of Internally Ignited Fires in Nuclear Power

Plant Control Cabinets: Part 1: Cabinet Effects Tests,” April 1987.

NUREG/CR-4330-Vol.3, “Review of Light Water Reactor Regulatory Requirements: Identifications

of Regulatory Requirements That May Have Marginal Importance to Risk: Post-Accident Sampling

System, Turbine Missiles, Combustible Gas Control, Filters,” Volume 3, May 1987.

NUREG/CR-4517, “An Aging Assessment of Relays and Circuits Breakers and System

Interactions,” June 1987.

NUREG/CR-4855, “Development and Application of a Computer Model for Large-Scale Flame

Acceleration Experiments,” July 1987.

NUREG/CR-4534, “Analysis of Diffusion Flame Tests,” August 1987.

NUREG/CR-5037, “Fire Environment Determination in the LaSalle Nuclear Power Plant Control

Room,” October 1987. 

NUREG/CR-5042, “Evaluation of External Hazards to Nuclear Power Plants in the United States,”

December 1987.

NUREG-1250, Rev. 1, “Report on the Accident at the Chernobyl Nuclear Power Station,” Prepared

by, the U.S. Department of Energy, Electric Power Research Institute, U.S. Environmental

Protection Agency, Federal Emergency Management Agency, Institute of Nuclear Power Operation,

and the U.S. Nuclear Regulatory Commission, December 1987.

NUREG/CR-4763, “Safety-Related Equipment Survival in Hydrogen Burns in Large Dry PWR

Containment Buildings,” March 1988.
D-38

NUREG/CR-2331, “Safety Research Programs Sponsored by Office of Nuclear Regulatory

Research,” Volume 7, No. 2 and 3, June 1988.

NUREG/CR-5233, “Computer Code for Fire Protection and Risk Analysis of Nuclear Plants,”

September 1988.

NUREG/CP-0097, “The Effects of Aging on the Fire Vulnerability of Nuclear Power Plant

Component,” Proceedings of the 16 Water Reactor Safety Meeting, October 1988. th

NUREG/CR-4527, Volume 2, “An Experimental Investigation of Internally Ignited Fires in Nuclear

Power Plant Control Cabinets: Part II: Room Effects Tests,” November, 1988. 

NUREG/CR-5088, “Fire Risk Scoping Study: Investigation of Nuclear Power Plant Fire Risk,

Including Previously Unaddressed Issues,” December 1988.

NUREG/CR-5088, “Fire Risk Scoping Study: Investigation of Nuclear Power Plant Fire Risk,

Including Previously Unaddressed Issues,” January 1989.

NUREG/CR-5042, Supplement 2, “Evaluation of External Hazards to Nuclear Power Plants in the

United States: Other External Events,” , February 1989. 

NUREG/CR-3037, “A Computer Code to Estimate Accidental Fire and Radioactive Airborne

Releases in Nuclear Fuel Cycle Facilities,” User's Manual for FIRIN, February 1989.

NUREG/CR-5281, “Value/Impact Analyses of Accident Preventive and Mitigative Options for Spent

Fuel Pools,” March 1989.

NUREG/CR-1251, Vol. 1, “Implications of the Accident at Chernobyl for Safety Regulation of

Commercial Nuclear Power Plants in the United States,” Volume 1, Main report: Final report. April

1989.

NUREG/CR-1251, Vol. 2, “Implications of the Accident at Chernobyl for Safety Regulation of

Commercial Nuclear Power Plants in the United Sates,” Volume 2, Appendix - Public Comments

and their Disposition: Final Report, April 1989.

NUREG-1335, “Individual Plant Examination: Submittal Guidance,” Final Report, Office of Nuclear

Regulatory Research, and Office of Nuclear Reactor Regulation, August 1989. 

NUREG/CR-5079, “Experimental Results Pertaining to the Performance of Thermal Igniters,”

October 1989.

NUREG/CR-5457, “Review of the Three Mile Island-1 Probabilistic Risk Assessment,” November

1989.

NUREG/CR-5384, “A Summary of Nuclear Power Plant Fire Safety Research at Sandia National

Laboratories,1975-1987,” December 1989.
D-39

NUREG/CR-5275, “FLAME Facility: The Effect of Obstacles and Transverse Venting on Flame

Acceleration and Transition to Detonation for Hydrogen/Air Mixture at Large Scale,” 1989.

NUREG/CR-5464, “An Identification and Initial Assessment of Potential Fire Safety Issues

Associated with Plant Aging,” April 1990.

NUREG-1409, “Backfitting Guidelines,” July, 1990.

NUREG-1150, Volume 1, “Severe Accident Risks: An Assessment for Five U.S. Nuclear Power

Plants,” December 1990.

NUREG/CR-4550, “Analysis of Core Damage Frequency: Peach Bottom Unit 2 External Events,”

December 1990.

NUREG/CR-4840, “Procedures for the External Event Core Damage Frequency Analyses for

NUREG-1150,” December 1990.

NUREG/CR-5619, “The Impact of Thermal Aging on the Flammability of Electric Cables,” March

1991.

NUREG/CR-5546, “An Investigation of the Effects of Thermal Aging on the Fire Damageability of

Electric Cables,” May 1991.

NUREG/CR-5655, “Submergence and High Temperature Steam Testing of Class 1E Electrical

Cables,” May 1991.

NUREG-1407, “Procedural and Submittal Guidance for the Individual Plant Examination of External

Events (IPEEE) for Severe Accident Vulnerabilities Study,” June 1991.

NUREG/CR-5525, “Hydrogen-Air-Diluent Detonation Study for Reactor Safety Analyses,” 1991.

NUREG/CR-5669, “Evaluation of Exposure Limits to Toxic Gases for Nuclear Reactor Control

Room Operations,” July 1991.

NUREG-1422, “Summary of Chernobyl Followup Research Activities,” U.S. Nuclear Regulatory

Commission, Division of Safety Issue Resolution, June 1992.

NUREG/CR-4839, “Methods for External Event Screening Quantification: Risk Methods Integration

and Evaluation Program (RMIEP) Methods Development, July 1992.

NUREG/CR-4832, “Analysis of the LaSalle Unit 2 Nuclear Power Plant: Risk Methods Integration

and Evaluation Program (RMIEP),” July 1992.

NUREG/CR-5790, “Risk Evaluation for a Babcock & Wilcox Pressurized Water Reactor, Effects of

Fire Protection System Actuation on Safety-Related Equipment: Evaluation of Generic Issue 57,”

September 1992.
D-40

NUREG/CR-4832, Volume 4, “Analysis of the LaSalle Unit 2 Nuclear Power Plant: Risk Methods

Integration and Evaluation Program (RMIEP). Initiating Events and Accident Sequence Delineation,”

October 1992.

NUREG/CR-5580, “Evaluation of Generic Issue 57: Effects of Fire Protection System Actuation on

Safety-Related Equipment,” (Vol.1, 2, 3, 4, and 5), December 1992 .

NUREG/CR-5789, “Risk Evaluation for a Westinghouse PWR, Effects of Fire Protection System

Actuation on Safety-Related Equipment: Evaluation of Generic Issue 57,” December 1992.

NUREG/CR-5791, “Risk Evaluation for a General Electric BWR, Effects of Fire Protection System

Actuation on Safety-Related Equipment: Evaluation of Generic Issue 57,” December 1992.

NUREG/CR-4832, “Analysis of the LaSalle Unit 2 Nuclear Power Plant: Risk Methods Integration

and Evaluation Program (RMIEP), Volume 9 , Internal Fire Analysis,” March 1993.

NUREG/CP-0129, Proceedings of the Workshop on Program for Elimination of Requirements

Marginal to Safety, Bethesda, Maryland, April 27-28, 1993.

NUREG-1364, “Resolution Regulatory Analysis For the Resolution of Generic Safety Issue 106:

Piping and the Use of Highly Combustible Gases in Vital Areas,” June 1993. 

NUREG/CP-0130-Vol.2, “Development of a Personal Computer Code for Fire Protection Analysis

of DOE Facility Air-cleaning Systems,” Proceedings of the 22 DOE/NRC Nuclear Air Cleaning nd

Conference, July 1993.

NUREG-1472, “Regulatory Analysis for the Resolution of Generic Issue 57: Effects of Fire

Protection System Actuation on Safety-Related Equipment,” October 1993.

BNL-NURG-49137, “Fire Protection of Safe Shutdown Capability at Commercial Nuclear Power

Plants,” 1993.

NUREG/CR-6103, “Prioritization of Reactor Control Components Susceptible to Fire Damage as

a Consequence of Aging,” January 1994.

NUREG/CR-5904, “Functional Issues and Environmental Qualification of Digital Protection Systems

of Advanced Light-Water Nuclear Reactors,” April 1994.

NUREG/CR-6095, “Aging, Loss-of-Coolant Accident (LOCA, and High Potential Testing of

Damaged Cables),” April 1994.

NUREG/CR-6143-Volume 3, “Evaluation of Potential Severe Accidents During Low Power and

Shutdown Operations at Grand Gulf, Unit 1: Analysis of Core Damage Frequency from Internal Fire

Events for Plant Operational State 5 During a Refueling Outage, July 1994,” 1994. 

NUREG/CR-6144-Volume 3-Pt.2, “Evaluation of Potential Severe Accidents During Low Power and

Shutdown Operations at Surry, Unit 1: Analysis of Core Damage Frequency from Internal Fires

During Mid-Loop Operations,” Volume 3, Part 2: Appendices, July 1994. 
D-41

NUREG/CR-6213, “High Temperature Hydrogen+Air+Steam Detonation Experiments in the BNL

Small Scale Development Apparatus,” August 1994.

NUREG/CR-6220, “An Assessment of Fire Vulnerability for Aged Electrical Relays,” March 1995.

NUREG/CR-6017, “Fire Modeling of the Heiss Dampf Reaktor Containment,” September 1995.

NUREG/CR-6358-Vol. 2, “Assessment of United States Industry Structural Codes and Standards

for Application to Advanced Nuclear Power Reactors,” Appendices, Volume 2, October 1995. 

NUREG/CP-0148, “Preliminary Studies on the Impact of Smoke on Digital Equipment,”

Transactions of the 23 Water Reactor Safety Information Meeting, Bethesda, Maryland, October rd

1995.

NUREG/CR-6173, “A Summary of the Fire Testing Program at the German HDR Test Facility,”

November 1995.

NUREG/CR-6384, “Literature Review of Environmental Qualification of Safety Related Electric

Cables,” Volume 1, April 1996. 

 

NUREG-1552, “Fire Barrier Penetration Seals in Nuclear Power Plants,” July 1996.

NUREG-1547, “Methodology for Developing and Implementing Alternative Time-Temperature

Curves for Testing the Fire Resistance of Barriers for Nuclear Power Plant Applications,” August

1996.

NUREG/CR-5973, “Codes and Standards and Other Guidance Cited in Regulatory Documents,”

August 1996.

NUREG/CR-6406, “Environmental Testing of an Experimental Digital Safety Channel,” September

1996.

NUREG/CR-6476, “Circuit Bridging of Components by Smoke,” October 1996.

NUREG/CR-6530, “Deliberate Ignition of Hydrogen-Air-Steam Mixtures in Condensing Steam

Environments,” May 1997.

NUREG-1601, “Chemical Process Safety at Fuel Cycle Facilities,” August 1997.

NUREG/CP-0153, “Potential for HEPA Filter Damage From Water Spray Systems in Filter

Plenums,” Proceedings of the 24 DOE/NRC Nuclear Air Cleaning and Treatment Conference,

th

August 1997, pp. 752–777.

NUREG-1611, “Aging Management of Nuclear Power Plant Containment for License Renewal,

Office of Nuclear Reactor Regulation, September 1997.

NUREG/CP-0161, “A Recent Results of an Experimental Study on the Impact on Digital I&C

Equipments,” Transactions of the 25 Water Reactor Safety Information Meeting, Bethesda, th

Maryland, October 20-22, 1997.
D-42

NUREG/CR-6543, “Effects of Smoke on Functional Circuits,” October 1997.

NUREG/CR-6479, “Technical Basis for Environmental Qualification of Microprocessor-Based

Safety-related Equipment in Nuclear Power Plants,” January 1998.

NUREG/CR-6410, “Nuclear Fuel Cycle Facility Accident Analysis Handbook,” March 1998.

NUREG/CR-6544, “Methodology for Analyzing Precursors to Earthquake-Initiated and Fire-Initiated

Accident Sequences,” April 1998.

NUREG/CR-6509, “The Effect of Initial Temperature on Flame Acceleration and Deflagration-toDetonation Transition Phenomenon,” May 1998.

NUREG-1521, “Technical Review of Risk-Informed, Performance-Based Methods for Nuclear

Power Plant Fire Protection Analyses,” Draft Report for Public Comments, Division of Risk Analysis

and Applications, Office of Nuclear Regulatory Research, July 1998.

NUREG/CR-6524, “The Effect of Lateral Venting on DDT in Hydrogen-Air-Steam Mixtures at

Various Temperature,” 1998.

NUREG-1552, Supplement 1, “Fire Barrier Penetration Seals in Nuclear Power Plants,” January

1999.

NUREG-0933, “A Prioritization of Generic Safety Issues,” April 1999.

BNL-NUREG-66831, “Fire Safety in Nuclear Power Plants: A Risk-Informed and PerformanceBased Approach,” November 1999.

NUREG/CP-0170, “International Collaborative Project to Evaluate Fire Models for Nuclear Power

Plant Applications: Summary of Planning Meeting,” Held at University of Maryland College Park,

Maryland, October 25-26, 1999, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory

Commission, Washington, DC, March 2000.

NUREG-1649, Revision 3, “Reactor Oversight Process,” July 2000.

NUREG/CR-6681, “Ampacity Derating and Cable Functionality for Raceway Fire Barriers,” August

2000.

NUREG-1738, “Technical Study of Spent Fuel Pool Accident Risk at Decommissioning Nuclear

Power Plants, January 2001.

NUREG/CR-6597, “Results and Insights on the Impact of Smoke on Digital Instrumentation and

Control,” January 2001.

NUREG/CP-0173, “International Collaborative Project to Evaluate Fire Models for Nuclear Power

Plant Applications: Summary of 2 Meeting,” Held at Institute for Protection and Nuclear Safety, nd

Fontenay-aux-Roses, France, June 19–20, 2000, Office of Nuclear Regulatory Research, U.S.

Nuclear Regulatory Commission, Washington, DC, March 2001.
D-43

NUREG-1800, “Standard Review Plan for Review of License Renewal Applications for Nuclear

Power Plants,” July 2001.

NUREG-1801, Volume 1, “Generic Aging Lessons Learned (GALL) Report—Summary,” July 2001.

NUREG-1801, Volume 2, “Generic Aging Lessons Learned (GALL) Report—Tabulation of Results,”

July 2001.

NUREG/CR-6738, “Risk Methods Insights Gained From Fire Incidents,” September 2001.

NUREG/CR-6752, “A Comparative Analysis of Special Requirements for Systems, Structures, and

Components (SSCs) of Nuclear Power Plants With Commercial Requirements of Non-Nuclear

Power Plants,” January 2002.

NUREG/CR-6042, Rev. 2, “Perspective on Reactor Safety,” March 2002.

NUREG-1753, “Risk-Based Performance Indicators: Results of Phase 1 Development,” April 2002.

NUREG-1742, Volume 1, Final Report, “Perspectives Gained from Individual Plant Examination of

External Events (IPEEE) Program,” Division of Risk Analysis and Applications, Office of Nuclear

Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC, April 2002.

NEREG-1742, Volume 2, Final Reports Tables, “Perspectives Gained from Individual Plant

Examination of External Events (IPEEE) Program,” Division of Risk Analysis and Applications,

Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC,

April 2002.

NUREG-1758, “Evaluation of Fire Models for Nuclear Power Plant Applications: Cable Tray Fires,

International Panel,” Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission,

Washington, DC, June 2002.

NUREG/CR-6776, “Cable Insulation Resistance Measurements Made During Cable Fire Tests,”

Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC,

June 2002.

NUREG/CR-6788, “Evaluation of Aging and Qualification Practices for Cable Splices Used in

Nuclear Power Plants,” Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory

Commission, Washington, DC, September 2002. 

NUREG/CP-0179, “Proceedings of the International Conference on Wire System Aging, Office of

Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC, November

2002.

NUREG/CR-6793, “Numerical Simulation of the Howard Street Tunnel Fire, Baltimore, Maryland,

July 2001,” Spent Fuel Project Office, Office of Nuclear Material Safety and Safeguards,

Washington, DC, January 2003. 
D-44

NUREG/CR-6799, Revision 1, “Analysis of Rail Car Components Exposed to a Tunnel Fire

Environment,” Spent Fuel Project Office, Office of Nuclear Material Safety and Safeguards,

Washington, DC, March 2003.

NUREG/CR-6834, “Circuit Analysis - Failure Mode and Likelihood Analysis,” Office of Nuclear

Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC, September 2003.

NUREG-1784, “Operating Experience Assessment: Effects of Grid Events on Nuclear Power Plant

Performance,” Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission,

Washington, DC, December 2003.

NUREG-1778, “Knowledge Base for Post-Fire Safe-Shutdown Analysis,” Draft Report for

Comments, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission,

Washington, DC, January 2004.
D-45

D.10 Safety Evaluation Reports Related to License Renewal for Operating Nuclear

Power Plants

NUREG-1705, “Safety Evaluation Report Related to the License Renewal of Calvert Cliffs Nuclear

Power Plant, Units 1 and 2,” December 1999.

NUREG-1723, “Safety Evaluation Report Related to the License Renewal of Oconee Nuclear

Station, Units 1, 2, and 3,” March 2000.

NUREG-1743, “Safety Evaluation Report Related to the License Renewal of Arkansas Nuclear

One, Unit 1,” May 2001.

NUREG-1803, “Safety Evaluation Report Related to the License Renewal of Edwin I. Hatch Nuclear

Plant, Units 1 and 2,” December 2001.

NUREG-1759, “Safety Evaluation Report Related to the License Renewal of Turkey Point Nuclear

Plant, Units 3 and 4,” April 2002.

NUREG-1766, “Safety Evaluation Report Related to the License Renewal of North Ann Power

Station, Units 1 and 2, and Surry Power Station, Units 1 and 2,” December 2002.

NUREG-1772, “Safety Evaluation Report Related to the License Renewal of McGuire Nuclear

Station, Units 1 and 2, and Catawba Nuclear Station, Units 1 and 2, March 2003.

NUREG-1769, “Safety Evaluation Report Related to the License Renewal of Peach Bottom Atomic

Power Station, Units 2 and 3,” March 2003.

NUREG-1782, “Safety Evaluation Report Related to the License Renewal of Fort Calhoun Station,

Unit 1,” October 2003.

NUREG-1785, “Safety Evaluation Report Related to the License Renewal of the H.B. Robinson

Steam Electric Plant, Unit 2,” March 2004.

NUREG-1787, “Safety Evaluation Report Related to the License Renewal of the Virgil C. Summer

Nuclear Station,” March 2004.

NUREG01796, “Safety Evaluation Report Related to the License Renewal of the Dresden Nuclear

Power Station, Units 2 and 3, and Quad Cities Nuclear Power Station, Units 1 and 2,” October 2004.
D-46

D.11 National Fire Protection Association (NFPA) Codes and Standards for Nuclear

Facilities

(1) NFPA 801, “Standard for Fire Protection for Facilities Handling Radioactive Materials,” 1998

Edition, National Fire Protection Association, Quincy, Massachusetts.

(2) NFPA 804, “Standard for Fire Protection for Advanced Light Water Reactor Electric

Generating Plants,” 2001 Edition, National Fire Protection Association, Quincy,

Massachusetts.

(3) NFPA 805, “Performance-Based Standard for Fire Protection for Light Water Reactor

Electric Generating Plants,” 2001 Edition, National Fire Protection Association, Quincy,

Massachusetts.
E-1

APPENDIX E. CURRENT NATIONAL FIRE PROTECTION

ASSOCIATION (NFPA) CODES AND STANDARDS

NFPA develops, publishes, and disseminates timely consensus codes and standards intended to

minimize the possibility and effects of fire and other risks. Virtually every building, process, service,

design, and installation in society today is affected by NFPA documents. More than 300 NFPA

codes and standards are used around the world. This series is referred to as the National Fire

Codes (NFC). 

NFPA codes and standards have great influence because they are widely used as a basis of

legislation and regulation at all levels of government, from local to international. Several NFPA

codes have received worldwide recognition, such as the Life Safety Code®, the National Electrical

Code®, and the National Fuel Gas Code. Many codes are referenced by Federal Government

agencies, such as the regulations of the U.S. Nuclear Regulatory Commission (NRC), General

Services Administration (GSA), and U.S. Occupational Safety and Health Administration (OSHA).

The documents are also used by insurance authorities for risk evaluation and premium rating and

as references in designs and specifications. Table E-1 provides titles of all current NFPA codes,

standards, and recommended practices. It is important to recognize that the NFPA codes and

standards are constantly revised and updated on 3 to 5 year cycles. The code or standard in effect

at the time of design or implementation is the code of record (COR) for that application.

Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

1 Uniform Fire CodeTM 2003

10 Standard for Portable Fire Extinguishers 2002

11 Standard for Low-Expansion Foam 2002

11A Standard for Medium-and High-Expansion Foam Systems 1999

12 Standard on Carbon Dioxide Extinguishing Systems 2000

12A Standard on Halon 1301 Fire Extinguishing Systems 1997

13 Standard for Installation of Sprinkler Systems 2002

13D Standard for Installation of Sprinkler Systems in One-and Two1-Family Dwellings

and Manufactured Homes

2002

13E Recommended Practice for Fire Department Operations in Properties Protected

by Sprinkler and Standpipe Systems

 2000

13R Standard for the Installation of Sprinkler Systems in Residential Occupancies up

to and Including Four Stories in Height 

2002

14 Standard for the Installation of Standpipe and Hose Systems 2003

15 Standard for Water Spray Fixed Systems for Fire Protection 2001
Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

E-2

16 Standard for the Installation of Foam-Water Sprinkler and Foam-Water Spray

Systems 

2003

17 Standard for Dry Chemical Extinguishing System 2002

17A Standard for Wet Chemical Extinguishing Systems 2002

18 Standard on Wetting Agents 1995

20 Standard for the Installation of Stationary Pumps for Fire Protection 1999

22 Standard for Water Tanks for Private Fire Protection 2003

24 Standard for the Installation of Private Fire Service Mains and Their

Appurtenances 

2002

25 Standard for the Inspection, Testing, and Maintenance of Water-Based Fire

Protection System

2002

30 Flammable and Combustible Liquids Code 2003

30A Code for Motor Fuel Dispensing Facilities and Repair Garages 2000

30B Code for the Manufacturer and Storage of Aerosol Products 2002

31 Standard for the Installation of Oil-Burning Equipment 2001

32 Standard for the Drycleaning Plants 2000

33 Standard for Spray Application Using Flammable or Combustible Materials 2000

34 Standard for Dipping and Coating Processes Using Flammable or Combustible

Liquids

2000

35 Standard for the Manufacturer of Organic Coatings 1999

36 Standard for Solvent Extraction Plants 2001

37 Standard for the Installation and Use of Stationary Combustion Engines and Gas

Turbines

2002

40 Standard for the Storage and Handling of Cellulose Nitrate Motion Picture Film 2001

42 Code for the Storage of Pyroxylin Plastic 2002

45 Standard on Fire Protection for Laboratories Using Chemicals 2000

50 Standard for Bulk Oxygen Systems at Consumer Sites 2001

50A Standard for Gaseous Hydrogen Systems at Consumer Sites 1999

50B Standard for Liquefied Hydrogen Systems at Consumer Sites 1999

51 Standard for the Design and Installation of Oxygen-Fuel Gas Systems for

Welding, Cutting, and Allied Processe 

2002
Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

E-3

51A Standard for Acetylene Cylinder Charging Plants 2001

51B Standard for Fire Prevention During Welding, Cutting, and Other Hot Work 1999

52 Compressed Nature Gas (CNG) Vehicular Fuel Systems Code 2002

53 Recommended Practice on Materials, Equipment, and Systems Used in OxygenEnriched Atmospheres 1999

54 National Fuel Code 2002

55 Standard for the Storage, Use, and Handling of Compressed Gases and

Cryogenic Fluids in Portable and Stationary Containers, Cylinders, and Tanks

2003

57 Liquified Petroleum Gas (LNG) Vehicular Fuel Systems Code 2002

58 Liquified Petroleum Gas Code 2001

59 Utility LP-Plant Code 2001

59A Standard for the Protection, Storage, and Handling of Liquefied Natural Gases

(LNG)

2001

61 Standard for the Prevention of Fires and Dust Explosions in Agriculture and Food

Products Facilities

2002

68 Guide for Venting of Deflagrations 2002

69 Standard on Explosion Prevention Systems 1997

70 National Electrical Code 2002 ®

70B Recommended Practice for Electrical Equipment Maintenance 2002

70E Standard for Electrical Safety Requirements for Employee Workshops 2000

72 National Fire Alarm Code 2002 ®

73 Electrical Inspection Code for Existing Dwellings 2000

75 Standard for the Protection of Information Technology Equipment 2003

76 Recommended Practice for the Fire Protection of Telecommunications Facilities 2002

77 Recommended Practice on Static Electricity 2000

79 Electrical Standard for Industrial Machinery 2002

80 Standard for Fire Doors and Fire Windows 1999

80A Recommended Practice for Protection of Building from Exterior Fire Exposures 2001

82 Standard on Incinerators and Waste and Linen Handling Systems and Equipment 1999

85 Boiler and Combustion Systems Hazards Code 2001
Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

E-4

86 Standard for Oven and Furnaces 1999

86C Standard for Industrial Furnaces Using a Special Processing and Equipment 1999

86D Standard for Industrial Furnaces Using Vacuum as an Atmosphere 1999

88A Standard for Parking Structures 2002

88B Standard for Repair Garages 1997

90A Standard for the Installation of Air-Conditioning and Ventilating Systems 2002

90B Standard for the Installation of Warm Air Heating and Air-Conditioning Systems 2002

91 Standard for Exhaust Systems for Air Conveying of Vapor, Gases, Mists, and

Noncombustibles Particulate Solids

1999

92A Recommended Practice for Smoke-Control Systems 2000

92B Guide for Smoke Management Systems in Mall, Atria, and Large Areas 2000

96 Standard for Ventilation Control and Fire Protection of Commercial Cooking

Operations

2001

97 Standard Glossary of Terms Relating to Chimneys, Vents, and Heat-Producing

Appliances

2003

99 Standard for Health Care Facilities 2002

99B Standard for Hypobaric Facilities 2002

101 Life Safety Code 2003 ® ®

101A Guide to Alternative Approaches to Life Safety 2001

101B Code for Mean of Egress for Buildings and Structures 2002

102 Standard for Grandstands, Folding and Telescopic Seating, Tents, and Membrane

Structures

1995

105 Standard for the Installation of Smoke Door Assemblies 2003

110 Standard for Emergency and Standby Power Systems 2002

111 Standard on Stored Electrical Energy Emergency and Standby Power Systems 2001

115 Recommended Practice on Laser Fire Protection 1999

120 Standard for Coal Preparation Plants 1999

121 Standard on Fire Protection for Self-Propelled and Mobile Surface Mining

Equipment

2001

122 Standard for Fire Prevention and Control in Underground Metal and Nonmetal

Mines

2000
Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

E-5

123 Standard for Fire Prevention and Control in Underground Bituminous Coal Mines 1999

130 Standard for Fixed Guideway Transit and Passenger Rail Systems 2000

140 Standard on Motion Picture and Television Production Studio 

Soundstages and Approved Production Facilities

1999

150 Standard on Fire Safety in Racetrack Stables 2000

160 Standard for Flame Effects Before an Audience 2001

170 Standard for Fire Safety Symbols 2002

203 Guide on Roof Coverings and Roof Deck Constructions 2000

204 Guide for Smoke and Heat Venting 2002

211 Standard for Chimneys, Fireplace, Vents, and Solid Fuel-Burning Appliances 2003

214 Standard on Water-Cooling Towers 2000

220 Standard on Types of Building Construction 1999

221 Standard for Fire Walls and Fire Barrier Walls 2000

225 Model Manufactured Home Installation Standard 2003

230 Standard for the Fire Protection of Storage 2003

232 Standard for the Protection of Records 2000

241 Standard for Safeguarding Construction, Alteration, and Demolition Operations 2000

251 Standard Methods of Tests of Fire Endurance of Building Construction and

Materials

1999

252 Standard Methods of Fire Tests of Door Assemblies 1999

253 Standard Method of Test for Critical Radiant Flux of Floor Covering Systems

Using a Radiant Heat Energy Source

2000

255 Standard Method of Test of Surface Burning Characteristics of Building Materials 2000

256 Standard Methods of Fire Tests of Roof Coverings 1998

257 Standard on Fire Test for Window and Glass Block Assemblies 2000

258 Recommended Practice for Determining Smoke Generation of Solid Materials 2001

259 Standard Test Method for Potential Heat of Building Materials 2003

260 Standard Methods of Tests and Classification System for Cigarette Ignition

Resistance of Components of Upholstered Furniture

1998
Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

E-6

261 Standard Method of Test for Determining Resistance of Mock-Up Upholstered

Furniture Material Assemblies to Ignition by Smoldering Cigarettes

1998

262 Standard Method of Test for Flame Travel and Smoke of Wires and Cables for

Use in Air-Handling Spaces

2002

265 Standard Methods of Fire Tests for Evaluating Room Fire Growth Contribution of

Textile Wall Coverings on Full Height Panels and Walls

2002

267 Standard Method of Test for Fire Characteristics of Mattresses and Bedding

Assemblies Exposed to Flaming Ignition Source

1998

268 Standard Test Method for Determining Ignitability of Exterior Wall Assemblies

Using a Radiant Heat Energy Source

2001

269 Standard Test Method for Developing Toxic Potency Data for Use in Fire Hazard

Modeling

2000

270 Standard Test Method for Measurement of Smoke Obscuration Using a Conical

Radiant Source in a Single Closed Chamber

2002

271 Standard Method of Test for Heat and Visible Smoke Release Rates for Materials

and Products Using an Oxygen Consumption Calorimeter

2001

272 Standard Method of Test for Heat and Visible Smoke Release Rates for

Upholstered Furniture Components or Composites and Mattresses Using an

Oxygen Consumption Calorimeter

2003

285 Standard Method of Test for the Evaluation of Flammability Characteristics of

Exterior Non-Load-Bearing Wall Assemblies Containing Combustible Components

Using the Intermediate-Scale, Multistory Test Apparatus

1998

286 Standard Methods of Fire Tests for Evaluating Contribution of Wall and Ceiling

Interior Finish to Room Fire Growth

2000

287 Standard Test Methods for Measurement of Flammability of Materials in

Cleanrooms Using a Fire Propagation Apparatus (FPA)

2001

288 Standard Methods of Fire Tests of Floor Fire Door Assemblies Installed

Horizontally in Fire Resistance–Rated Floor Systems 

2001

291 Recommended Practice for Fire Flow Testing and Marking of Hydrants 2002

295 Standard for Wildfire Control 1998

301 Code for Safety to Life from Fire on Merchant Vessels 2001

302 Fire Protection Standard for Pleasure and Commercial Motor Craft 1998

303 Fire Protection Standard for Marinas and Boatyards 2000

306 Standard for the Control of Gas Hazards on Vessels 2001
Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

E-7

307 Standard for the Construction and Fire Protection of Marine Terminals, Piers, and

Wharves

2000

312 Standard for Fire Protection of Vessels During Construction, Repair, and Lay-Up 2000

318 Standard for the Protection of Cleanrooms 2000

326 Standard for the Safeguarding of Tanks and Containers for Entry, Cleaning, or

Repair

1999

329 Recommended Practice for Handling Releases of Flammable and Combustible

Liquids and Gases

1999

385 Standard for Tank Vehicles for Flammable and Combustible Liquids 2000

402 Guide for Aircraft Rescue and Fire Fighting Operations 2002

403 Standard for Aircraft Rescue and Fire-Fighting Services at Airports 1998

405 Recommended Practice for the Recurring Proficiency Training of Aircraft Rescue

and Fire-Fighting Services

1999

407 Standard for Aircraft Fuel Servicing 2001

408 Standard for Aircraft Hand Portable Fire Extinguishers 1999

409 Standard on Aircraft Hangars 2001

410 Standard on Aircraft Maintenance 1999

412 Standard for Evaluating Aircraft Rescue and Fire-Fighting Foam Equipment 1998

414 Standard for Aircraft Rescue and Fire-Fighting Vehicles 2001

415 Standard on Airport Terminal Buildings, Fueling Ramp Drainage, and Loading

Walkways

2002

418 Standard for Heliports 2001

422 Guide for Aircraft Accident Response 1999

423 Standard for Construction and Protection of Aircraft Engine Test Facilities 1999

424 Guide for Airport/Community Emergency Planning 2002

430 Code for the Storage of Liquid and Solid Oxidizers 2000

432 Code for the Storage of Organic Peroxide Formulations 2002

434 Code for the Storage of Pesticides 2002

450 Guide for Emergency Medical Services and Systems 2003

471 Recommended Practice for Responding to Hazardous Materials Incidents 2002
Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

E-8

472 Standard on Professional Competence of Responders to Hazardous Materials

Incidents

2002

473 Standard for Competencies for EMS Personnel Responding to Hazardous

Materials Incidents

2002

484 Standard for Combustible Metals, Metal Powders, and Metal Dusts 2002

490 Code for the Storage of Ammonium Nitrate 2002

495 Explosive Materials Code 2001

496 Standard for Purged and Pressurized Enclosures for Electrical Equipment 1998

497 Recommended Practice for the Classification of Flammable Liquids, Gases, or

Vapors and of Hazardous (Classified) Locations for Electrical Installations in

Chemical Process Areas

1997

498 Standard for Safe Havens and Interchange Lots for Vehicles Transporting

Explosives

2001

499 Recommended Practice for the Classification of Combustible Dusts and of

Hazardous (Classified) Locations for Electrical Installations in Chemical Process

Areas

1997

501 Standard on Manufactured Housing 2003

501A Standard for Fire Safety Criteria for Manufactured Home Installations, Sites, and

Communities

2003

502 Standard for Road Tunnels, Bridges, and Other Limited Access Highways 2001

505 Fire Safety Standard for Powered Industrial Trucks Including Type Designations,

Areas of Use, Conversions, Maintenance, and Operation

2002

520 Standard on Subterranean Spaces 1999

550 Guide to the Fire Safety Concepts Tree 2002

551 Guide for the Evaluation of Fire Risk Assessments 2003

555 Guide on Methods for Evaluating Potential for Room Flashover 2000

560 Standard for the Storage, Handling, and Use of Ethylene Oxide for Sterilization

and Fumigation

2002

600 Standard on Industrial Fire Brigades 2000

601 Standard for Security Services in Fire Loss Prevention 2000

610 Guide for Emergency and Safety Operations at Motorsports Venues 2003

654 Standard for the Prevention of Fire and Dust Explosions from the Manufacturing,

Processing, and Handling of Combustible Particulate Solids

2000
Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

E-9

655 Standard for Prevention of Sulfur Fires and Explosions 2001

664 Standard for the Prevention of Fires and Explosions in Wood Processing and

Woodworking Facilities

2002

701 Standard Methods of Fire Tests for Flame Propagation of Textiles and Films 1999

703 Standard for Fire Retardant Impregnated Wood and Fire Retardant Coatings for

Building Materials

2000

704 Standard System for the Identification of the Hazards of Materials for Emergency

Response

2001

705 Recommended Practice for a Field Flame Test for Textiles and Films 1997

720 Recommended Practice for the Installation of Household Carbon Monoxide (CO)

Warning Equipment

2003

730 Premises Security Code 2003

731 Installation of Premises Security Equipment 2003

750 Standard on Water Mist Fire Protection Systems 2003

780 Standard for the Installation of Lightning Protection Systems 2000

801 Standard for Fire Protection for Facilities Handling Radioactive Materials 2003

804 Standard for Fire Protection for Advanced Light Water Reactor Electric

Generating Plants

2001

805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric

Generating Plants

2001

820 Standard for Fire Protection in Wastewater Treatment and Collection Facilities 1999

850 Recommended Practice for Fire Protection for Electric Generating Plants and

High Voltage Direct Current Converter Stations

2000

851 Recommended Practice for Fire Protection for Hydroelectric Generating Plants 2000

853 Standard for the Installation of Stationary Fuel Cell Power Plants 2000

900 Building Energy Code 2003

901 Standard Classifications for Incident Reporting and Fire Protection Data 2001

906 Guide for Fire Incident Field Notes 1998

909 Code for the Protection of Cultural Resources 2001

914 Code for Fire Protection of Historic Structures 2001

921 Guide for Fire and Explosion Investigations 2001
Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

E-10

1000 Standard for Fire Service Professional Qualifications Accreditation and

Certification Systems 

2000

1001 Standard on Fire Fighter Professional Qualifications 2002

1002 Standard for Fire Apparatus Driver/Operator Professional Qualifications 1998

1003 Standard for Airport Fire Fighter Professional Qualifications 2000

1006 Standard for Rescue Technician Professional Qualifications 2003

1021 Standard on Fire Officer Professional Qualifications 1997

1031 Standard for Professional Qualifications for Fire Inspector and Plan Examiner 1998

1033 Standard for Professional Qualifications for Fire Investigator 1998

1035 Standard for Professional Qualifications for Public Fire and Life Safety Educator 2000

1041 Standard for Fire Service Instructor Professional Qualifications 2002

1051 Standard for Wildland Fire Fighter Professional Qualifications 2002

1061 Standard for Professional Qualifications for Public Safety Telecommunicator 2002

1071 Standard for Emergency Vehicle Technician Professional Qualifications 2000

1081 Standard for Industrial Fire Brigade Member Professional Qualifications 2001

1122 Code for Model Rocketry 2002

1123 Code for Fireworks Display 2000

1124 Code for the Manufacture, Transportation, Storage, and Retail Sales of Fireworks

and Pyrotechnic Articles

2003

1125 Code for the Manufacture of Model Rocket and High Power Rocket Motors 2001

1126 Standard for the Use of Pyrotechnics before a Proximate Audience 2001

1127 Code for High Power Rocketry 2002

1141 Standard for Fire Protection in Planned Building Groups 1998

1142 Standard on Water Supplies for Suburban and Rural Fire Fighting 2001

1145 Guide for the Use of Class A Foams in Manual Structural Fire Fighting 2000

1150 Standard on Fire-Fighting Foam Chemicals for Class A Fuels in Rural, Suburban

and Vegetated Area

1999

1192 Standard on Recreational Vehicles 2002

1194 Standard for Recreational Vehicle Parks and Campgrounds 2002
Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

E-11

1201 Standard for Developing Fire Protection Services for the Public 2000

1221 Standard for Installation, Maintenance, and Use of Emergency Service

Communications Systems

2002

1250 Recommended Practice in Emergency Service Organization Risk Management 2000

1401 Recommended Practice for Fire Service Training Reports and Records 2001

1402 Guide to Building Fire Service Training Centers 2002

1403 Standard on Live Fire Training Evolutions 2002

1404 Standard for a Fire Department Self-Contained Breathing Apparatus Program 2002

1405 Guide for Land-Based Fire Fighters Who Respond to Marine Vessel Fires 2001

1410 Standard on Training for Initial Emergency Scene Operations 2000

1451 Standard for a Fire Service Vehicle Operations Training Program 2002

1452 Guide for Training Fire Service Personnel to Conduct Dwelling Fire Safety

Surveys

2000

1500 Standard on Fire Department Occupational Safety and Health Program 2002

1521 Standard for Fire Department Safety Officer 2002

1561 Standard on Emergency Services Incident Management System 2002

1581 Standard on Fire Department Infection Control Program 2000

1582 Standard on Medical Requirements for Fire Fighters and Information for Fire

Department Physicians

2000

1583 Standard on Health-Related Fitness Programs for Fire Fighters 2000

1584 Recommended Practice on the Rehabilitation of Members Operating at Incident

Scene Operations and Training Exercises 

2003

1600 Standard on Disaster/Emergency Management and Business Continuity

Programs

2000

1620 Recommended Practice for Pre-Incident Planning 1998

1670 Standard on Operations and Training for Technical Rescue Incidents 1999

1710 Standard for the Organization and Deployment of Fire Suppression Operations,

Emergency Medical Operations, and Special Operations to the Public by Career

Fire Department

2001

1720 Standard for the Organization and Deployment of Fire Suppression Operations,

Emergency Medical Operations, and Special Operations to the Public by

Volunteer Fire Departments

2001
Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

E-12

1851 Standard on Selection, Care, and Maintenance of Structural Fire Fighting

Protective Ensembles

2001

1852 Standard on Selection, Care, and Maintenance of Open-Circuit Self Contained

Breathing Apparatus (SCBA)

2002

1901 Standard for Automotive Fire Apparatus 1999

1906 Standard for Wildland Fire Apparatus 2001

1911 Standard for Service Tests of Fire Pump Systems on Fire Apparatu 2002

1912 Standard for Fire Apparatus Refurbishin 2001

1914 Standard for Testing Fire Department Aerial Devices 2002

1915 Standard for Fire Apparatus Preventive Maintenance Program 2000

1925 Standard on Marine Fire-Fighting Vessels 1998

1931 Standard on Design of and Design Verification Tests for Fire Department Ground

Ladders

1999

1932 Standard on Use, Maintenance, and Service Testing of Fire Department Ground

Ladders

1999

1936 Standard on Powered Rescue Tool Systems 1999

1951 Standard on Protective Ensemble for USAR Operations 2001

1961 Standard on Fire Hose 2002

1962 Standard for the Inspection, Care, and Use of Fire Hose, Couplings, and Nozzles

and the Service Testing of Fire Hose

2003

1963 Standard for Fire Hose Connections 1998

1964 Standard for Spray Nozzles 2003

1971 Standard on Protective Ensemble for Structural Fire Fighting 2000

1975 Standard on Station/Work Uniforms for Fire and Emergency Services 1999

1976 Standard on Protective Ensemble for Proximity Fire Fighting 2000

1977 Standard on Protective Clothing and Equipment for Wildland Fire Fighting 1998

1981 Standard on Open-Circuit Self-Contained Breathing Apparatus for the Fire Service 2002

1982 Standard on Personal Alert Safety Systems (PASS) 1998

1983 Standard on Fire Service Life Safety Rope and System Components 2001

1989 Standard on Breathing Air Quality for Fire and Emergency Services Respiratory

Protection

2003
Table E-1-1. NFPA Codes and Standards

NFPA Title Edition

E-13

1991 Standard on Vapor-Protective Ensembles for Hazardous Materials Emergencies 2000

1992 Standard on Liquid Splash-Protective Ensembles and Clothing for Hazardous

Materials Emergencies

2000

1994 Standard on Protective Ensembles for Chemical/Biological Terrorism Incidents 2001

1999 Standard on Protective Clothing for Emergency Medical Operations 2003

2001 Standard on Clean Agent Fire Extinguishing Systems 2000

2112 Standard on Flame-Resistant Garments for Protection of Industrial Personnel

Against Flash Fire

2001

2113 Standard on Selection, Care, Use, and Maintenance of Flame-Resistant

Garments for Protection of Industrial Personnel Against Flash Fire

2001

5000 Building Construction and Safety CodeTM 2003

F-1

APPENDIX F. GLOSSARY OF FIRE PROTECTION TERMS

The purpose of this appendix is to provide definitions and meanings of fire protection engineering

term being used in the field of fire science, engineering, and technology today. This appendix

contains a collection of terminology and a description of terms and can be used as reference source

to understand basic terminology used in fire protection engineering. The reference for the definition

is provided in parentheses.

accelerant—a material (gas, liquid, or solid) used to initiate or promote the spread of fire incident.

Most accelerants are highly flammable. (Nolan, 2000)

access door—a fire door smaller than conventional doors provides access to utility shafts, chases,

manways, plumbing, and various other concealed spaces and equipments.

(NFC Online Glossary)

abort switch—a manually activated switch provided for fixed gaseous fire suppression system to

cancel the signal to release and discharge the system agent. The use of an abort switch is

preferred over other manual means, such as portable fire extinguishers or when a false alarm

condition is immediately known, to avoid the unnecessary release of large quantities of fire

suppression agent. An abort switch is only practical where individuals may be present to

immediately investigate the cause of the system activation and have time to activate the switch.

absolute temperature—a temperature measured in Kelvin (K) or degree Rankine (R). Zero is the

lowest possible temperature and 273 K corresponds to 0 °F and 460 °R corresponds to 0 °F. 

K = °C + 273 and °R = °F + 460. (Nolan, 2000)

access door, horizontal—an access door installed in the horizontal plane used to protect openings

in fire-rated floors or ceilings of floor–ceiling or roof–ceiling assemblies. 

(NFC Online Glossary)

access door, vertical—an access door installed in the vertical plane used to protect openings in

fire-rated walls. (NFC Online Glossary)

access floor system—an assembly consisting of panels mounted on pedestals to provide an

under-floor space for the installations of mechanical, electrical communication, or similar systems

or to serve as an air supply or return-air plenum. (NFC Online Glossary)

access openings—a window, panel, or similar opening meeting the following criteria: (a) The

opening has minimum dimensions of not less than 22 in. (55.9 cm) in width and 24 in. (61 cm) in

height and is unobstructed to allow for ventilation and rescue operations from the exterior, and (b)

The bottom of the opening is not more than 44 in. (112 cm) above the floor, and (c) The opening

is readily identifiable from both the exterior and interior, and (d) The opening is readily openable

from both the exterior and interior. (NFC Online Glossary)

access panel—a closure device used to cover an opening into a duct, an enclosure, equipment,

or an appurtenance. (NFC Online Glossary)

accessible—having access to but which first may require the removal of a panel, door, or similar

covering of the item described. (NFC Online Glossary)
F-2

accessible (as applied to wiring methods)—capable of being removed or exposed without damaging

the building structure or finish, or not permanently closed in by the structure or finish of the building.

(NFC Online Glossary)

accessible—(as applied to equipment.) Admitting close approach; not guarded by locked doors,

elevation, or other effective means. (NFC Online Glossary)

accessible means of egress—a path of travel, usable by a person with a severe mobility

impairment, that leads to a public way or an area of refuge and that complies with the accessible

route requirements of ICC/ANSI A117.1, “American National Standard for Accessible and Usable

Buildings and Facilities”.(NFC Online Glossary)

accommodation area—a group of accommodation spaces and interconnecting corridors or spaces.

(NFC Online Glossary)

accommodation space—spaces designed for living purposes. 

(NFC Online Glossary)

accommodation spaces—accommodation spaces shall include, but are not limited to, all portions

of a vessel used for such purposes as overnight residence, deliberation, worship, entertainment,

dining, or amusement. Accommodation spaces shall include the following: (a) passenger or crew

cabins (b) lounge areas (c) athletic facilities (d) gaming areas (e) office spaces (f) spaces for

religious worship (g) theaters (h) restaurants/messing areas (i) public toilets/washrooms (j) public

sales/shops. (NFC Online Glossary)

active fire barrier—a fire barrier element that must be physically repositioned from its normal

configuration to an alternate configuration in order to provide its protective function. Example

include ventilation system fire dampers and normally open fire door. 

activation energy—the minimum energy that colliding fuel and oxygen molecules must possess to

permit chemical interaction. (NFC Online Glossary)

active fire protection—a fire protection method that requires manual, mechanical, or other means

of initiation, replenishment, or sustenance for its performance during a detected hazard or fire

incident. Typical activations include switching on, directing, injecting, or expelling in order to

combat smoke, flame, or thermal loadings. Fire sprinkler systems and manual firefighting efforts

are examples. Active systems are commonly composed of an integrated detection, signaling, and

automated fire control system. (Nolan, 2000)

active smoke detection system—a fire detection system where smoke is transported to and into a

sampling port to aspirate smoke into the detector-sensing chamber rather than relying totally on

outside forces such as fire plume strength or environmental air flows. These systems actively draw

smoke into the sensing chamber through the use of suction fans. Smoke in the immediate vicinity

of the sampling ports is drawn into the detector-sensing chamber. (Nolan, 2000)

adiabatic—Referring to any change in which there is no gain or loss of heat. (McGraw-Hill) 
F-3

adiabatic flame temperature—the maximum possible flame temperature that can be achieved by

a particular combustion process (with no hat loss from the combustion). For example, the adiabatic

flame temperatures for hydrocarbon fuels burning in air range from 2,000 °C to 2,300 °C 

(3,632 °F to 4,172 °F). (Nolan, 2000)

advanced light-water reactors (ALWR)—advanced light water reactors are divided into two types:

(a) evolutionary plants. These are simpler, improved versions of conventional designs employing

active safety systems. (b) revolutionary plants. These are the result of completely rethinking the

design philosophy of conventional plants. Revolutionary plants currently being proposed replace

mechanical safe shutdown systems with passive features that rely on physical properties such as

natural circulation, gravity flow, and heat sink capabilities. (NFC Online Glossary)

aerosol—A gaseous suspension of ultramicroscopic particles of a liquid or a solid. (McGraw-Hill)

aerosol detector—a detector designed to be activated by the liquid and solid particulates in smoke.

AFFF-Aqueous Film Forming Foam—a foam that forms a spreading aqueous film over the surface

of a flammable liquid. AFFF is a combination of fluorocarbon surfactants and synthetic foam

agents. They produce a foam that slides across the surface of hydrocarbon fuels. This is

accomplished by the formation of a film that spreads ahead of the foam bubbles. 

(NFC Online Glossary)

air sampling-type detector—a detector that consists of a piping or tubing distribution network that

runs from the detector to the area(s) to be protected. An aspiration fan in the detector housing

draws air from the protected area back to the detector through air sampling ports, piping, or tubing.

At the detector, the air is analyzed for fire products.

air/fuel ratio, air-rich—the ratio of air to fuel by weight or volume which is significant for proper

oxidative combustion of the fuel. (McGraw-Hill)

alarm—a signal indicating an emergency that requires immediate action, such as a signal indicative

of fire. (Nolan, 2000)

alarm signal—a signal indicating a concentration of carbon monoxide that could pose a risk to the

life safety of the occupants in the family living unit, requiring immediate action. 

(NFC Online Glossary)

alarms and indicators—any device capable of providing audible, visual, or olfactory indication.

alternative shutdown capability—the ability to safely shut down the reactor and maintain shutdown

using equipment and processes outside the normal reactor shutdown process. 

ambient temperature—the temperature of the surrounding medium; usually used to refer to the

temperature of the air in which a structure is situated or a device operates.
F-4

American Wire Gauge (AWG)—a standardized system used to designate the size or “gauge” of

wire. As the diameter of wire gets smaller, the “AWG” number of the wire gets larger. The smallest

AWG size is 40 and looks like a metal thread. “Four ought” (0000) is the largest AWG wire size

designation. Wires larger than this size are designated by the Thousand Circular Mill system or

“KCMIL” sizes (known until recently as MCM).

ampacity—the current, in amperes, that a conductor can carry continuously under the conditions

of use without exceeding its temperature rating. 

analysis, sensitivity—an analysis performed to determine the degree to which a predicted output

will vary given a specified change in an input parameter, usually in relation to models. 

(NFC Online Glossary)

analysis, uncertainty—an analysis performed to determine the degree to which a predicted value

will vary. (NFC Online Glossary)

analyzer, gas—a device that measures concentrations, directly or indirectly, of some or all

components in a gas or mixture. (NFC Online Glossary)

annunciator—a unit containing two or more identified targets or indicators lamps in which each

target or lamp indicates the circuit, condition, or location to be annunciated. 

(NFC Online Glossary)

antifreeze sprinkler system—a wet pipe sprinkler system employing automatic sprinklers that are

attached to a piping system that contains an antifreeze solution and that are connected to a water

supply. The antifreeze solution is discharge, followed by water, immediately upon operation of

sprinklers opened by heat from a fire. (NFC Online Glossary)

Appendix R cables—the set of cables that must remain free of fire damage to ensure safe

shutdown conditions can be achieved within established criteria.

Appendix R fire area—an area, as defined in the Appendix R analysis, sufficiently bounded by fire

barriers that will withstand the fire hazards within the fire area and, as necessary, to protect

important equipment within a fire area from a fire outside the area the area. A fire area must be

made up of rated fire barriers with openings in the barriers provided with fire doors, fire dampers,

and fire penetration seal assemblies having a fire resistance rating at least equivalent to the barrier

in which it is installed.

Appendix R fire zones—subdivisions of a fire area.

Appendix R requirements—fire protection requirements specified in Appendix R to 10 CFR 50, “Fire

Protection Program for Nuclear Power Facilities Operating Prior to January 1, 1979,” (It should be

noted that while some specific Appendix R requirements apply to all plants operating prior to

January 1, 1979, plants licensed after January 1, 1979, are not subject to Appendix R requirements.

These plants must meet the fire protection condition of their licenses which are based upon the

guidelines of NUREG-0800, specifically Branch Technical Position CMEB 9.5-1, which mirrors

Appendix R with additional information).
F-5

approach fire fighting—limited, specialized exterior fire fighting operations at incidents involving fires

producing very high levels of conducted, convective, and radiant heat, such as bulk flammable gas

and bulk flammable liquid fires. Speciality thermal protection from exposure to high levels of radiant

heat is necessary for the persons involved in such operations due to the limited scope of these

operations and greater distance from the fire that these operations are conducted. Not entry,

proximity, or structural, or wildland fire-fighting. (NFC Online Glossary)

approved—tested and accepted for a specific purpose or application by a recognized testing

laboratory. (Regulatory Guide 1.189)

approved—acceptable to authority having jurisdiction. (NFPA 805)

aqueous film-forming foam (AFFF) concentrate—a concentrated aqueous solution of fluorinated

surfactant(s)and foam stabilizers that is capable of producing an aqueous fluorocarbon film on the

surface of hydrocarbon fuels to suppress vaporization. (NFC Online Glossary)

arcing—the flashing occurring at electrical terminals when the circuit has been opened or closed.

armored cable—type AC armored cable is a fabricated assembly of insulated conductors in a

flexible metallic enclosure. (NFC Online Glossary)

assembly—a unit or structure composed of a combination of materials or products, or both. 

(NFC Online Glossary)

assembly occupancy—an occupancy (1) used for a gathering of 50 or more persons for

deliberation, worship, entertainment, eating, drinking, amusement, awaiting transportation, or

similar uses; or (2) used as a special amusement building, regardless of occupant load. 

(NFC Online Glossary)

associated circuits—circuits that do not meet the separation requirements for safe shutdown

systems and components and are associated with safe shutdown systems and components by

common power supply, common enclosure, or the potential to cause spurious operations that could

prevent or adversely affect the capability to safely shutdown the reactor as a result of fire induced

failure (hot shorts, open circuits, and short to ground). (Regulatory Guide 1.189)

associated circuit analysis—a documented, systematic, evaluation of associated circuits of concern

to post-fire safe shutdown.

atmospheric pressure—the pressure of the weight of air and water vapor on the surface of the

earth, approximately 14.7 pounds per square inch (psia) (101 kPa absolute) at sea level. 

(NFC Online Glossary)

atmospheric tank—a storage tank that has been designed to operate at gauge pressures from

atmospheric through 0.5 psi (3.45 kPa). (NFC Online Glossary)

atmospheric vents—all points where pipes, stacks, or ducts are open to the atmosphere including

discharge points from emissions control devices, vent pipes from safety valves, vent pipes from

filters or pumps, and other vents. (NFC Online Glossary)
F-6

Authority Having Jurisdiction (AHJ)—the organization, office, or individual responsible for approving

equipment, materials, an installation, or a procedure. (NFPA 805)

autoignition—the initiation of fire or combustion process by external heat without the application of

a spark or flame. (NFC Online Glossary)

autoignition temperature—the lowest temperature at which a mixture of fuel and oxidizer can

propagate a flame without the aid of an initiating energy source (pilot, a spark or flame).

autoignition temperature—the lowest temperature at which a vapor/air mixture within its flammability

limits can undergo spontaneous ignition.

automatic closing device—a mechanism that can be fitted to a door which will cause the door to

close if there is a fire.

automatic door release—a device on a self-closing door that holds the door open during normal

operation but causes it to close by releasing electromagnetic holders when activated by a signal,

such as from a fire alarm. The closed door prevents the spread of fire and smoke. For personnel

exit applications and other locations where smoke spread is a concern, fusible links or other similar

heat-activated door-closing devices are not recommended because smoke may pass through the

door opening before there is sufficient heat to melt the fusible device. (Nolan, 2000)

automatic fire alarm system—a system of controls, initiating devices, and alarm signals in which

all or some of the initiating circuits are activated by automatic devices, such as smoke detectors.

(Nolan, 2000)

automatic fire detection system—an arrangement of detectors that ascertains the presence of a

combustion process by sensing heat, smoke, or flames. The detectors can be self-annunciating or

connected to a fire alarm control panel (FACP) to initiate other alarm devices or signaling systems.

Various codes and standards are used to design and provide a fire alarm system, notably NFPA 72,

“National Fire Alarm Code ”. (Nolan, 2000) ®

automatic fire door—a fire door that closes immediately following the detection of a fire incident.

Most fire doors that automatically close are held open by electromagnetic holders. When the fire

is detected by a fire detection system, power is removed from the magnetic holders, and the doors

swing closed from their self-closer. It may also be called an automatic-closing fire door.

(Nolan, 2000)

automatic fire extinguishing system—a fire suppression system that automatically senses the

occurrence of a fire and signals a control device for the application of extinguishing agents. It is

designed to distribute and apply the extinguishing agents in sufficient quantities and densities to

effect fire control and extinguishment. No human intervention is required. Almost all automatic fire

extinguishing systems are required to be designed and installed according to prescribed rules and

regulations that ensure they are reliable and effective for fire protection applications. (Nolan, 2000)

automatic fire protection—active fire protection measures that are activated immediately following

a fire incident without human intervention. Automatic fire protection systems pro-vide for both fire

detection and extinguishment. (Nolan, 2000)
F-7

automatic sprinkler—a water spray device, commonly a nozzle with a perpendicular spray deflector

attached, used to deflect the water spray to a predetermined area at a predetermined density for

the purpose of fire protection. Automatic sprinklers for fire protection applications are available in

a variety of configurations and decorative features. The sprinklers for fire protection are normally

required to be tested or approved by an independent testing agency (UL or FM). Sprinklers may

be installed with an open orifice (dry sprinklers) or provided with an element that contains the

system water supply (wet sprinklers). Water is sprayed from the sprinkler once the heat from a fire

causes a fusible element in the sprinkler head to melt. Once the element has melted it releases a

tension mounted cap on the outlet of the sprinkler. The sprinkler outlet is connected to a water

distribution pipe network. Water pressure in the pipe network directs water onto the sprinkler

deflector, providing the water spray. (Nolan, 2000)

auxiliarized local system—a local system that is connected to the municipal alarm facilities.

auxiliarized proprietary system—a proprietary system that is connected to the municipal alarm

facilities. 

auxiliary protective signaling system—a connection to the municipal fire alarm system to transmit

an alarm of fire to the municipal communication center. Fire alarms from an auxiliary center on the

same equipment and by the same alerting methods as alarms transmitted from municipal fire alarm

boxes located on streets.

back pressure—pressure against which a fluid is flowing, resulting from friction in lines, restrictions

in pipes or valves, pressure in vessel to which fluid is flowing, hydrostatic head, or other impediment

that causes resistance to fluid flow. (NFC Online Glossary)

Backdraft—limited ventilation during an enclosure fire can lead to the production of large amount

of unburnt gases. When an opening is suddenly introduced, the inflowing air may mix with these,

creating a combustible mixture of gases in some part of the enclosure. Any ignition sources, such

as a flowing ember, can ignite this flammable mixture, resulting in an extremely rapid burning of the

gases. Expansion due to the heat created by the combustion will expel the burning gases out

through the opening and cause a fireball outside the enclosure. The phenomenon can be

extremely hazardous. (NFC Online Glossary)

backfire arrester—a flame arrester installed in fully premixed air–fuel gas distribution piping to

terminate flame propagation therein, shut off fuel supply, and relieve pressure resulting from a

backfire. (NFC Online Glossary)

barrier —a part providing protection against direct contact from any usual direction of access. 

(IEC 50-826.) (NFC Online Glossary)

barrier failure—the breach of a fire barrier, by a fire or other cause, which could permit propagation

of a fire or its combustion products across the barrier.

barrier material—a single-layer fabric or a laminated or coated, multilayer material considered as

a single-layer fabric that limits transfer from the face of the layer to the other side. 

(NFC Online Glossary)
F-8

barrier, smoke—a continuous membrane, or a membrane with discontinuities created by protected

openings, where such membrane is designed and constructed to restrict the movement of smoke.

(NFC Online Glossary)

barrier, thermal—a material that limits the average temperature rise of an unexposed surface to not

more than 120 °C (250 °F) for a specified fire exposure complying with the standard

time-temperature curve of NFPA 251, “Standard Methods of Tests of Fire Endurance of Building

Construction and Materials”. (NFC Online Glossary)

blackbody temperature—the temperature of a perfect radiator; a surface with an emissivity of unity

and, therefore, a reflectivity of zero. (NFC Online Glossary)

blanketing (or padding)—a technique of maintaining an atmosphere that is either inert or fuelenriched in the vapor space of a container or vessel. (NFC Online Glossary)

blast—a transient change in the gas density, pressure, and velocity of the air surrounding an

explosion point. The initial change can be either discontinuous or gradual. A discontinuous change

is referred to as a shock wave, and a gradual change is known as a pressure wave. Blast is also

called pressure wave. (Nolan, 2000)

blast area—the area including the blast site and the immediate adjacent area within the influence

of flying rock, missiles, and concussion. (NFC Online Glossary)

blast pressure front—the expanding leading edge of an explosion reaction that separates a major

difference in pressure between normal ambient pressure ahead of the front and potentially

damaging high pressure at and behind the front. (NFC Online Glossary)

blast site—the area where explosive material is handled during loading of the blasthole, including

15.3 m (50 ft) in all directions from the perimeter formed by loaded holes. A minimum of 9.15 m 

(30 ft) can replace the 15 m (50 ft) requirement if the perimeter for loaded holes is marked and

separated from nonblast site areas by a barrier. The 15.3 m (50 ft) or 9.15 m (30 ft) distance

requirements, as applicable, apply in all directions along the full depth of the blasthole. In

underground mines, at least 4.6 m (15 ft) of a solid rib, pillar, or broken rock can be substituted for

the 15.3 m (50 ft) distance. (NFC Online Glossary)

blasting agent—a material or mixture intended for blasting that meets the requirements of the DOT

“Hazardous Materials Regulations,” as set forth in Title 49, Code of Federal Regulations, Parts

173.56, 173.57, and 173.58, Explosive 1.5D. (NFC Online Glossary)

blaze—terminology for a free-burning fire characterized as spectacular in flame evolution.

Boiling Liquid Expanding Vapor Explosion (BLEVE) —a catastrophic rupture of a pressurized vessel

containing a liquid at a temperature above its normal boiling point with the simultaneous ignition of

the vaporizing fluid. A short-duration, intense fireball occurs if the liquid is flammable. During the

rupture of the vessel, a pressure wave may be produced and fragments of the containment vessel

will be thrown considerable distances. (Nolan, 2000)
F-9

boilover—a phenomenon that can occur during a fire over an open tank containing a blend of

flammable liquids, such as crude oil; water must be present at the bottom of the tank for boilover

to occur. (Friedman, 1998)

boiling point—the maximum temperature at which a liquid can evaporate under normal; atmospheric

conditions; equilibrium temperature for a liquid and its vapor to coexist at 1 atmosphere of pressure.

boiling point—the temperature at which the vapor pressure of a liquid equals the surrounding

atmospheric pressure. For purposes of defining the boiling point, atmospheric pressure shall be

considered to be 14.7 psia (760 mm Hg). For mixtures that do not have a constant boiling point,

the 20 percent evaporated point of a distillation performed in accordance with ASTM D86, Standard

Method of Test for Distillation of Petroleum Products, shall be considered to be the boiling point.

(NFC Online Glossary)

bounding analysis—an analysis that intentionally makes use of methods and assumptions (e.g.,

those pertaining to parameters describing a hazard, a resulting initiating event, and a plant’s

resistance to the initiator) designed to result in an upper-bound or demonstrably conservative

estimate of risk.

British Thermal Unit (Btu)—the quantity of heat required to raise the temperature of one pound of

water -17 °C (1 °F) at the pressure of one atmosphere and the temperature of 60 °F (15.5 °C).

building characteristics—a set of data that provides a detailed description of a building, such as

building layout (geometry), access and egress, construction, building materials, contents, building

services, and fire safety (hardware) systems. (NFC Online Glossary)

building code—a set of requirements intended to ensure that an acceptable level of safety

(including fire safety) is incorporated into a building at the time of construction.
F-10

building construction types—there are five general types of building construction classifications

defined for fire protection purposes. They are classified according to their fire resistive properties.

They include the following (Nolan, 2000):

• fire resistive—a broad range of structural systems capable of withstanding fires of specified

intensity and duration without failure. Common fire-resistive components include masonry

load- bearing walls, rein-forced concrete or protective steel columns, and poured or precast

concrete floors and roofs (Ref. NFPA 220, Type I).

• noncombustible—type of structure made of noncombustible materials in lieu of fire-resistant

materials. Steel beams, columns, and masonry or metal walls are used (Ref. NFPA 220,

Type II).

• ordinary—consists of masonry exterior load-bearing walls that are of noncombustible

construction. Interior framing, floors, and roofs are made of wood or other combustible

materials, whose bulk is less than that needed to qualify as heavy-timber construction. If

the floor and roof construction and their supports have a one-hour fire resistance rating and

all openings through the floors (stairwells) are enclosed with partitions having a one-hour

fire resistance rating, then the construction is classified as “protected ordinary construction”

(Ref. NFPA 220, Type III).

• heavy timber—characterized by masonry walls, heavy-timber columns and beams, and

heavy plank floors. Although not immune to fire, the large mass of the wooden members

slows the rate of combustion. Heavy timber construction can be used where the smallest

dimension of the members exceeds 5.5 in. (14 cm). When timbers are this large, they are

charred but not consumed in a fire and are generally considered akin to a fire-resistant type

of construction (Ref. NFPA 220, Type IV).

• wood frame—building construction characterized by use of wood exterior walls, partitions,

floors, and roofs. Exterior walls may be sheathed with brick veneer, stucco, or metal-clad

or asphalt siding (Ref. NFPA 220, Type V).

building occupancy—the primary activity for which a building is designed and built. Fire code

requirements are based on the risk a building occupancy represents, and, therefore, various

building occupancies are normally defined by a fire code. Common building occupancies include

assembly, business, educational, factory or industrial, hazardous or high hazard, institutional,

mercantile, residential, storage and utility, special, or miscellaneous. (Nolan, 2000)

building services—provisions, such as heating, plumbing, electrical and air handling systems, that

render a building habitable.

burning rate—the combustion rate of a fuel, expressed either as the rate of mass consumption per

unit exposed area.

burnout—point at which flames cease. (Nolan, 2000)

burning velocity—the speed with which a laminar flame moves in a direction normal to its surface,

relative to the unburned portion of combustible gas mixture, at constant pressure. Its value

depends on mixture composition, temperature, and pressure. 
F-11

buoyancy—an effective force on fluid due to density or temperature differences in a gravitational

field. (NFC Online Glossary)

burn injury—an injury to the skin and deeper tissues caused by hot liquids, flames, radiant heat,

and direct contact with hot solids, caustic chemicals, electricity, or electromagnetic (nuclear)

radiation. A first-degree burn injury occurs with a skin temperature of about 48 °C (118 °F), and

a second-degree burn injury occurs with a skin temperature of 55 °C (131 °F). Instantaneous skin

destruction occurs at 72 °C (162 °F). Inhaling hot air or gases can also burn the upper respiratory

tract.

The severity of a burn depends on its depth, its extent, and the age of the victim. Burns are

classified by depth as first, second, and third degree. First-degree burns cause redness and pain

(sun-burn) and affect only the outer skin layer. Second-degree burns penetrate beneath the

superficial skin layer and are marked by edema and blisters (scalding by hot liquid). In third-degree

burns, both the epidermis and dermis are destroyed, and underlying tissue may also be damaged.

It has a charred or white leathery appearance and initially there may be a loss of sensation to the

area. The extent of a burn is expressed as the percent of total skin surface that is injured.

Individuals less than 1 year old and over 40 years old have a higher mortality rate than those

between 2 and 39 years old for burns of similar depth and extent. Inhalation of smoke from a fire

also significantly increases mortality. Thermal destruction of the skin permits infection, which is

the most common cause of death for extensively burned individuals. Body fluids and minerals are

lost through the wound. The lungs, heart, liver, and kidneys may be affected by infection and fluid

loss. First aid for most burns involves the application of cool water as soon as possible after the

burn. Burns of 15-percent of the body surface or less are usually treated in hospital emergency

rooms by removing dead tissue (debridement), dressing with antibiotic cream (often silver

sulfadiazine), and administering oral pain medication. Burns of 15 to 25-percent of the body

surface often require hospitalization to provide intravenous fluids and avoid complications. Burns

of more than 25-percent of the body surface are usually treated in specialized burn centers.

Aggressive surgical management is directed toward early skin grafting and avoidance of such

complications as dehydration, pneumonia, kidney failure, and infection. Pain control with

intravenous narcotics is frequently required. The markedly increased metabolic rate of severely

burned patients requires high-protein nutritional supplements given intravenously and by mouth.

Extensive scarring of deep burns may cause disfigurement and limitation of joint motion. Plastic

surgery is often required to reduce the effects of the scars. Psychological problems often result

from scarring. Investigations are underway to improve burn victims’ nutritional support, enhance

the immune response to infection, and grow skin from small donor sites in tissue culture to cover

large wounds. Since over 50 percent of all burns are preventable (separation, barriers, protective

clothing, etc.), safety programs can significantly reduce the incidence of burn injuries.

(Nolan, 2000)

cable failure—a breakdown in the physical and/or chemical properties (e.g., electrical continuity,

insulation integrity) of cable conductor(s) such that the functional integrity of the electrical circuit can

not be assured (e.g., interrupted or degraded).

cable jacket—a protective covering over the insulation, core, or sheath of a cable.

(IEEE Std.100-1988).
F-12

cable penetration—an assembly or group of assemblies for electrical conductors to enter and

continue through a fire-rated structural wall, floor, or floor-ceiling assembly. 

(IEEE Std. 100-1988).

cable routing—the pathway electrical wiring takes through the plant from power source or control

point to component location.

cable-to-cable fault—a fault condition of relatively low impedance between conductors of one cable

and conductors of a different cable.

cable tray fire break—a noncombustible or limited-combustible material used for vertical cable trays

to limit fire spread.

carbon dioxide—colorless, odorless, electrically nonconductive inert gas that is a suitable medium

for extinguishing Class B and Class C fires. Liquid carbon dioxide forms dry ice (snow) when

released directly into the atmosphere. Carbon dioxide gas is 11⁄2 times heavier than air. Carbon

dioxide extinguishers fire by reducing the concentrations of oxygen, the vapor phase of the fuel, or

both in the air to the point where combustion stops. (NFC Online Glossary)

C-factor—a relative roughness coefficient used in mathematical calculations of friction losses for

water flow in pipes for fire protection systems when using the Hazen-Williams friction loss formula.

C-factors are dependent on the smoothness of the internal surfaces of pipes and are features of

the pipe material and system age. A high C factor (120) represents a smooth internal pipe and a

low C-factor (80 or 90) is a rough internal pipe surface. The C- factor decreases as the level of

friction within the pipe interior surface increases. When computerized hydraulic programs are used

to determine water pressures and flow conditions within a water distribution system, the friction

coefficients to use are specified as part of the input data. Common piping C factors used for fire

protection applications include the following (Nolan, 2000):

• Unlined Cast or Ductile Iron - 100

• Asbestos Cement, Cement-Lined

• Cast or Ductile Iron, Cement-Lined

• Steel and Concrete - 140

• Polyethylene, Polyvinyl Chloride (PVC), and Fiberglass 

• Epoxy-150 Copper - 150

calorimetry—the heat release rate for a fire is the most significant measure of the magnitude and

destructive potential of a fire. The growth rate of the fire is determined by the burning rate

characteristics of the fuel as well as the ignitability, flame spread, and geometry of the item. Given

the significant complexities of the fire growth process, there is a need to be able to experimentally

measure the heat release rate history of combustibles materials. The method for measuring heat

release rates are collectively referred to as calorimetry.

While it is in principle to possible to measure the heat output of a fire by thermal means, early

attempts to use thermal methods were generally unsatisfactory due to practical details of instrument

design. Modern calorimeters makes use of the empirical fact that the heat released per unit of

oxygen consumed is a constant, 13 kJ/g of oxygen. This direct relationship between oxygen

consumption and heat release means that a measurement of oxygen depletion can be used to

measure the heat release rate.
F-13

cavitation—formation of a partial vacuum (creating gas bubbles), in a liquid by a swiftly moving solid

body (a propeller). Cavitation may occur in a firewater pumping system due to improper design,

arrangement, or installation. The generation and collapse of the gas bubbles produce a vibration

and sometimes severe mechanical strain on the pumping system, reducing performance and

causing accelerated deterioration of the pumping components (especially the impeller). Specific

design and installation requirements are set forth in NFPA 20, “Standard for the Installation of

Stationary Pumps for Fire Protection,” to prevent cavitation from occurring in fixed fire-water pump

installations.

ceiling jet—the radially outward flow under a ceiling resulting when a fire plume impinges on a

ceiling. (Friedman, 1998) 

6 10 5 n

cellulosic—a natural polymer (C H O ) , which is a principle constituent of cotton, wood, and paper.

(Friedman, 1998)

cellulosic fire—a fire with a fuel source com-position predominantly of cellulose (wood, paper,

cotton, etc.). A fire involving these materials is relatively slow growing, although its intensity may

ultimately reach or exceed that of a hydrocarbon fire. Standard building fire barriers are based on

a cellulosic fire exposure as defined by ASTM E119, “Standard Test Methods for Fire Tests of

Building Construction and Materials,”; ISO Standard No. 834; or BS 476 Part 20. Cellulosic fires

reach a maximum temperature of just over 900 °C (1,652 °F).

central station system (or Central station firealarm system)—A fire alarm system controlled and

operated by a designated business for fire alarm system operation and maintenance. All signals

generated by the system report to a central station (office) and are acted upon as required. 

(Nolan, 2000)

Celsius temperature—a temperature scale on which pure water at sea level freezes at 0 °C and

boils at 100 °C (212 °F). (Friedman, 1998)

char—the carbonaceous remains of burned materials. 

charring—the production of a solid carbonaceous residue on heating or burning a solid.

circuit failure modes—open circuit - a condition that is experienced when an individual conductor

within a cable loses electrical continuity.

• short-to-ground—a condition that is experienced when an individual conductor comes in

electrical contract with a grounded conducting device, such as a cable tray, conduit , or

metal housing.

• hot short—a condition that is experienced when individual conductors of the same or

different cables come in contact with each other.
F-14

Class of fires (NFPA 10, 2002 Edition)—a letter designation given to a particular fire category for

the purpose of generally classifying it accordance to the type if fuel and possible spread of fire.

• Class A Fires—fires in ordinary combustible materials, such as , wood, cloth, paper, rubber,

and many plastics.

• Class B Fires—fires in flammable liquids, combustibles liquids, petroleum greases, tars,

oils, oil-based paints, solvents, lacquers, alcohols, and flammable gases,.

• Class C Fires—fires that involve energized electrical equipment where the electrical nonconductivity of the extinguishing media is of importance. (When electrical equipment is deenergized, fire extinguishers foe Class A or Class B fires can be use safely).

• Class D Fires—fires in combustible metals, such as magnesium, titanium, zirconium,

sodium, lithium, and potassium.

• Class K Fires—fires in cooking appliances that involve combustible cooking media

(vegetable or animal oils and fats).

circuit—a conductor or system of conductors through which electrical current flows.

(IEEE Std.100-1988)

circuit—interconnection of components to provide an electrical path between two or more

components.

circuit breaker—a device designed to open and close a circuit by nonautomatic means, and to open

the circuit automatically on a predetermined overload of current without injury to itself when properly

applied within its rating. 

(IEEE Std 100-1988)

circuit breaker—a mechanical switching device capable of making, carrying and breaking currents

under normal circuit conditions and also, making, carrying for a specified period of time, and

breaking currents under specified abnormal circuit conditions such as those of short circuit.

(IEEE Std. 100-1988)

clean agent—a volatile or gaseous fire extinguishing agent that is not electrically conductive and

does not leave any residue during or after its application following evaporation. Common clean

agents include carbon dioxide, Halon, Inergen, and FM-200. Although Halon is considered a clean

agent, it may contribute to the Earth’s ozone depletion and therefore is considered environmentally

harmful. (Nolan, 2000)

clean agent fire suppression system (CAFSS)—a fire suppression application system that utilizes

a volatile or gaseous fire extinguishing agent that is not electrically conductive and does not leave

any residue during or after its application following evaporation. (Nolan, 2000)

closed-circuit self-contained breathing apparatus (SCBA)—a recirculation-type SCBA in which the

exhaled gas is rebreathed by the wearer after the carbon dioxide has been removed from the

exhalation gas and the oxygen content within the system has been restored from sources such as

compressed breathing air, chemical oxygen, liquid oxygen, or compressed gaseous oxygen.

code—comprehensive set of requirements intended to address fire safetyin a facility. Code may

reference numerous standards.
F-15

code of record—the codes and standards refer to the edition of the code or standard in effect at the

time of fire protection systems or features was designed or specifically committed to the authority

having jurisdiction.

cold smoke—smoke that is produced from a smoldering fire. The fire itself does not generate

adequate quantities of heat to produce a flaming fire. Cold smoke therefore lacks the buoyancy of

smoke from a flaming fire because its low heat content does not generate a strong convection

current. Cold smoke may be more difficult to detect by ceiling mounted smoke detectors due to its

lack of buoyancy. (Nolan, 2000)

combustion—the burning of gas, liquid, or solid, in which the fuel is oxidized, evolving heat and

often light. (McGraw-Hill)

combustion efficiency—the ratio of heat actually developed in a combustion process to the heat that

would be released if the combustion were perfect. (McGraw-Hill)

combustible gas detector—an instrument designed to detect the presence or concentration of

combustible gases or vapors in the atmosphere. It is usually calibrated to indicate the concentration

of a gas as a percentage of its lower explosive limit (LEL) so that a reading of 100-percent indicates

that the LEL has been reached. They use either a solid-state circuit, infrared (IR) beam,

electrochemical, or dual catalytic bead for the detection of gas in an area. Portable monitors are

used for personnel protection and fixed installations are provided for property protection.

combustible liquid—as generally defined, it is any liquid that has a closed-cup flash point at or

above 100 °F (37.8 °C). Combustible liquids are classified as Class II or Class III, and flammable

liquids are classified as IA, IB or IC. (NFPA 30)

• Class II Liquid—any liquid tested with a flash point at or above 37.8 °C (100°F) and below

60 °C (140°F).

• Class III A—any liquid tested with a flash point at or above 60 °C (140 °F), but below 93 °C

(200 °F).

• Class III B—any liquid tested with a flash point at or above 93 °C (200 °F).

combustible liquid area-fixed—an area used for storage of Class II and Class III combustible liquids

that is infrequently moved, and where the aggregate quantity present shall not exceed 5,000 gallon

(18, 925 L). Handling of liquids incidental to transfer can take place within a storage area.

(NFC Online Glossary)

combustible liquid area-large—an area used for storage of Class II and Class III combustible

liquids where the aggregate quantity present shall not exceed 1,000 gallon (3,785 L). Handling of

liquids incidental to transfer can take place within a storage area. (NFC Online Glossary)

combustible liquid area-mobile—self-propelled or mobile equipment fitted with suitable containers

or tanks and other related fixtures used for the storage, transport, and dispensing of Class II and

Class III combustible liquids. The aggregate quantity of combustible liquid carried on such

equipment shall not exceed 1,000 gallon (3,785 L). (NFC Online Glossary)
F-16

combustible liquid area-portable—an area used for storage of Class II and Class III combustible

liquids that is periodically moved, and where the aggregate quantity present shall not exceed 1,000

gallon (3,785 L). Handling of liquids incidental to transfer can take place within a storage area.

(NFC Online Glossary)

combustible liquid area-small—an area used for storage of Class II and Class III combustible

liquids that is periodically moved, and where the aggregate quantity present shall not exceed 60

gallon to 1,000 gallon (227 L to 3,785 L). Handling of liquids incidental to transfer can take place

within a storage area. (NFC Online Glossary)

combustible material—any material that will burn or sustain the combustion process when ignited

or otherwise exposed to fire conditions. (Regulatory Guide 1.189)

common enclosure—an enclosure (e.g., cable tray, conduit, junction box) that contains circuits

required for the operation of safe shutdown components and circuits for non-safe shutdown

components.

common-mode failure—multiple failures that are attributable to a common cause. 

(IEEE Std. 100-1988.

common power supply/source—a power supply that feeds safe shutdown circuits and non-safe

shutdown circuits (Regulatory Guide 1.189)

common path of travel—the portion of an exit access that building occupants must traverse before

two distinct paths of travel or two exits are available. (NFC Online Glossary)

compartmentation—a type of building design in which a building is divided into sections that can

be closed off from each other so that there is resistance to fire spread beyond the area of origin.

compartmentation—a fire protection strategy whereby a building is subdivided into compartments

that are separated from one another by fire resistant barriers.

complete combustion—refers to the chemical reaction where all the product components are in their

most stable state.

compressed breathing gas—a respirable gas mixture stored in a compressed state and supplied

to the user in a gaseous form. (NFC Online Glossary)

compressed gas—any material or mixture having, when in its container, an absolute pressure

exceeding 40 psia (an absolute pressure 276 kPa) at 21.1 °C (70 °F) or, regardless of the pressure

at 21.1 °C (70 °F), having an absolute pressure exceeding 104 psia (an absolute pressure of 717

kPa) at 54.4 °C (130 °F). (NFC Online Glossary)

computer fire model—a computer fire model is normally realized as a computer program for

predicting fire. This is most common, but not necessarily always true. A computer fire model, for

example, could be realized as only a flowchart. 

concentration—the percentage of material per unit mass (or volume) of its mixture.
F-17

conduction—the mode of heat transfer associated with solid in direct contact, or heat transfer due

to molecular energy transfer following Fourier’s Law.

conductor—a substance or body that allows a current of electricity to pass continuously along it.

(IEEE Std. 100-1988)

conductor—a wire or combination of wires, not insulated from one another, suitable for carrying an

electric current. (IEEE Std. 100-1988)

conductor-to-conductor fault—a circuit fault condition of relatively low impedance between two or

more conductors of the same or different circuit.

conductor-to-conductor fault—a cable failure mode of relatively low impedance between two or

more conductors of the same multi-conductor cable (Intra-cable fault) or between two or more

separate cables (Inter-cable fault).

configuration factor—fraction of radiation received by a target compared to the total emitted by the

source.

conflagration or mass fire—a fire over a large tract of land where generally the flames are much

shorter than the horizontal extent of the fire.

construction joint—see seismic gap penetration seal.

contain a fire—to take suppression action that can reasonably be expected to check the fire spread

under prevailing and predicted conditions.

control of burning—application of water spray to equipment or areas where a fire can occur to

control the rate of burning and thereby limit the heat release from a fire until the fuel can be

eliminated or extinguishment effects.

control cable—cable applied at relatively low current levels or used for intermittent operation to

change the operating status of a utilization device of the plant auxiliary system. 

(IEEE Std. 100-1988)

control circuit—the circuit that carries the electrical signals directing the performance of the

controller but does not carry the main power circuit (IEEE Std. 100-1988).

control panel—an assembly of man/machine interface devices (IEEE Std. 100-1988).

control power/voltage—the voltage applied to the operating mechanism of a device to actuate it.

(IEEE Std. 100-1988)

control-power transformer—a transformer which supplies power to motors, relays, and other

devices used for control purposes. (IEEE Std. 100-1988)

control a fire—to complete a control line around a fire, any spot fire therefrom, or any interior island

to be saved; to burn out any unburned area adjacent to the fire side of the control line and cool

down all hot spots that are an immediate threat to the control line.(NFC Online Glossary)
F-18

convection—the heat transfer associated with fluid movement around the heated body. Warmer,

less dense fluid rises and is replaced by cooler, more dense fluid. Convection current rise during

a fire event due to heat transfer to the surrounding air, causing it to rise and allow cooler air to enter

the fire environment at the base of the fire.

convective heat—energy that is carried by a hot moving fluid.

convective heat transfer coefficient—a quantity that represent the ability of heat to be transformed

from a moving fluid to a solid surface expressed in terms of heat flux per unit temperature

difference.

consequences—consequences are expected effects from the realization of the hazard and severity,

usually measured in terms of property damage, business interruption, life safety exposure,

environmental impact, company image etc.

corrosion-resistant material—materials such as brass, copper, monel, stainless steel, or other

equivalent corrosion-resistant materials. (NFC Online Glossary)

cracking—pyrolysis; breaking gaseous molecules into other molecules.

credited shutdown equipment—the set of equipment that is relied on (credited in the SSA) for

achieving post-fire safe shutdown conditions in the event of fire in a specific fire area. 

creep—the high temperatures [over 500 °C (1,000 °F)] reached during fire greatly accelerate the

creep strain rate (gradual degradation) in a building element. Although this time-dependent strain

is important in all building elements, its effects are critical in the case of tension loads in structural

steel members are reinforcing steel. The influence of creep strain on elements should be

considered in all but the most gross estimates of fire resistance. An increase in creep strain rate

will have the net effect of increased deformation. In general, the stress relief provided by increased

creep strain may preclude catastrophic failures in steel beams. 

critical heat flux—a threshold level of heating below which ignition (or in other context, flame

spread) is not possible.

critical temperature—the temperature at which a structural metal (such as steel) softens when

heated and can no longer support load. It is usually below its melting temperature.

cross-linked polymer—a polymer in which the long chains are bonded to one another at

intermediate points. Cross-linked reduces flexibility and tendency to melt, and increase the

tendency to form char on heating. (Friedman, 1998)

cross-zoning—a method of fire detection whereby adjacent fire detectors are connected to different

sensing circuits to the fire alarm control panel. Confirmed fire detection is only achieved if two

detectors are activated, one from each of the separate alarm circuits. Cross-zoning is used primarily

as a deterrent against false alarms and in particular where a fixed fire suppression system (such

as a 2 CO system) is arranged to automatically discharge upon fire detection to avoid accidental

release of the suppression gas. It may also be referred to as a voting system. 

(Nolan, 2000)
F-19

cross-zone analysis—the analysis of a potential fire scenario involving fire propagation between

adjacent fire zones.

cryogenic gas—a refrigerated, liquid gas having a boiling point below -90 °C (-130 °F) at

atmospheric pressure. (NFC Online Glossary)

current licensing basis (CLB)—the set of NRC requirements applicable to a specific plant and a

licensee's written commitments for ensuring compliance with and operation within applicable NRC

requirements and the plant-specific design basis (including all modifications and additions to such

commitments over the life of the license) that are docketed and in effect. The CLB includes the

NRC regulations contained in 10 CFR Parts 2, 19, 20, 21, 26, 30, 40, 50, 51, 54, 55, 70, 72, 73, 100

and appendices thereto; orders; license conditions; exemptions; and technical specifications. It also

includes the plant-specific design-basis information defined in 10 CFR 50.2 as documented in the

most recent final safety analysis report (FSAR) as required by 10 CFR 50.71 and the licensee's

commitments remaining in effect that were made in docketed licensing correspondence such as

licensee responses to NRC bulletins, generic letters, and enforcement actions, as well as licensee

commitments documented in NRC safety evaluations or licensee event reports. (10 CFR 54.3)

See also: Regulatory Guide 1.189.

curtain wall—an exterior wall non-load bearing prefabricated wall, usually more than one story high

supported by the structural frame, which protects the building’s interior from weather, noise, or fire.

damper, fire—a device (damper) arranged to seal off airflow automatically through part of an air

distribution system to resist the passage of heat and flame. It is usually an assembly of louvers

arranged to close from the heat of a fire by melting a fusible link or through a remote activation

signal. Fire dampers are required by all building codes to maintain the required level of fire

resistance rating for walls, partitions, and floors when they are penetrated by air ducts or other

ventilation openings. There are two significant ratings when applying a fire damper; the fire

resistance rating and the airflow closure rating. The fire rating is dependent on meeting the fire

resistant rating of the fire barrier being penetrated by the airflow duct and the airflow rating is either

static or dynamic, depending on whether the air flow is automatically shut down upon fire detection.

(NFC Online Glossary)

damper, smoke—a damper arranged to restrict the spread of smoke in a heating, ventilation and

air conditioning (HVAC) air duct system. It is designed to automatically shut off air movement in the

event of a fire. It is usually applied in a Passive Smoke Control System or as part of an Engineered

Smoke Control System to control the movement of smoke within a building when the HVAC is

operational in an engineered smoke control system. HVAC control fans are used to create pressure

differences in conjunction with fixed barriers (walls and floors). Higher pressures surround the fire

area and prevent the spread of smoke from the fire zone into other areas of the building. A smoke

damper also can be a standard louvered damper serving other control functions, provided the

location lends itself to the dual purpose. A smoke damper is not required to meet all the design

functions of a fire damper. Smoke dampers are classified according to leakage rates: Class 1

(lowest), 2, 3, and 4 (highest); elevated temperature 250 °F (121 °C), 350 °F (177 °C) or higher; and

prescribed pressure and velocity differences at the damper (specific velocity of airflow when open

and to close against a specific pressure differential). (NFC Online Glossary)

dead end—a corridor, hallway, or passageway open to a corridor that can be entered from the exit

access without passage through a door, but which does not lead to an exit.
F-20

dedicated smoke control systems—systems that are intended for the purpose of smoke control

only. They are separate systems of air moving and distribution equipment that do not function

under normal building operating conditions. Upon activation, these systems operate specifically

to perform the smoke control function.

dedicated shutdown—the ability to shut down the reactor and maintain shutdown conditions using

structures, systems, or components dedicated to the purpose of accomplishing post-fire safe

shutdown functions. (Regulatory Guide 1.189)

deep-seated fire—a deep-seated fire occurs when the burning solid material (e.g., cable) is not just

a surface burning phenomena but pyrolysing beneath the surface. This is postulated to occur

when the cable fire has reached the stage of a fully developed fire. Extinguishment of a surface

does not guarantee a deep-seated fire may also be eliminated. Extinguishment of deep-seated

fires requires an individual to investigate the interior of a material once the surface fire has been

extinguished to determine if interior extinguishment has also been accomplished. If a deep-seated

fire in an enclosed area is to be extinguished by a gaseous agent, the period of agent concentration

has to be adequate to ensure suppression has been accomplished. 

deep-seated fire—a deep-seated fire may become established beneath the surface of fibrous or

particulate material. This condition may result from flaming combustion at the surface or from the

ignition within the mass of fuel. Smoldering combustion then progresses slowly through the mass.

A fire of this kind is referred to in this standard as a “deep-seated” fire. The burning rate of these

fires can be reduced by the presence of Halon 1301, and they may be extinguished if a high

concentration can be maintained for an adequate soaking time. However, it is not normally

practical to maintain a sufficient concentration of Halon 1301 for a sufficient time to extinguish

deep-seated fires.

defense-in-depth—a principle aimed at providing a high degree of fire protection by achieving a

balance of (a) preventing fores from starting (b) detecting fires quickly and suppressing those fires

that occur, thereby limiting damage; and (c) designing the plant to limit the consequences of fire

to life, property, environment, continuity of plant operation, and safe shutdown capability. It is

recognized that, independently, no one of these items is complete in itself. Strengthening any item

can compensate for weaknesses, known or unknown, in the other items.

deflagration—mechanism for the propagation of an explosion reaction through a flammable gas

mixture that is thermal in nature. The velocity of the reaction is always less than the speed of

sound in the mixture but is capable of causing damage. A deflagration is possible if a gases

concentration rises above its lower flammability limit (LFL). (Nolan, 2000)

deflagration pressure containment—the technique of specifying the design pressure of a vessel and

its appurtenances so they are capable of withstanding the maximum pressure resulting from an

internal deflagration. (Nolan, 2000)

deflagration suppression—the technique of detecting and arresting combustion in a confined space

while the combustion is still in its incipient stage, thus preventing the development of pressure that

could result in an explosion. (Nolan, 2000)

deluge—the immediate release of a commodity, usually referring to a water spray release for fire

suppression purposes. (Nolan, 2000)
F-21

deluge sprinkler system—a system that uses open sprinklers or nozzles so that all flow water is

discharged when the deluge valve actuates.

deluge water mist system—water mist system with open nozzles that discharge water mist

simultaneously from all nozzles on the system.

density—the property of a substance which is expressed by the ratio of its mass to its volume.

design fire curve—an engineering description of the development of a fire for use in a design fire

scenario. Design fire curves might be described in terms of heat release rate versus time.

design fire scenario—a set of conditions that defines or describe the critical factors for determining

outcomes of trial designs.

detonation—propagation of a combustion zone at a velocity that is greater than the speed of sound

in the un-reacted medium. (NFC Online Glossary)

developing fire—the early stage of growth (in a compartment fire) before flashover and full

involvement.

diffusion—process of species transport in a mixture from its high to low concentration.

diffusion flame—a flame in which the fuel and oxygen are transported (diffused) from opposite sides

of the reaction zone (flame). (Nolan, 2000)

dimensionless—having no units of measure (terms combine to produce no units).

draft curtains—barriers suspended from the roof of a structure to limit the spread of smoke.

dry chemicals—a power composed of very small particles, usually sodium bicarbonate, potassium

bicarbonate, or ammonium phosphate-based with added particulate supplemented by special

treatment to provide resistance to packing, resistance to moisture absorption (caking), and the

proper flow capabilities. (NFC Online Glossary)

Early Suppression Fast Response (ESFR) sprinkler—an automatic fire sprinkler designed to

activate quickly from fire conditions. ESFR sprinklers have a thermal element with a response time

index (RTI) of 50 (meters-seconds) or less. Standard sprinklers have a thermal element with an 1/2

RTI of 80 (meters-seconds) or more. ESFR sprinklers are used for special high hazard 1/2

applications. Large drop ESFR sprinklers are specifically designed for wet pipe sprinkler systems

protecting high-piled storage commodity applications. They were developed by the Factory Mutual

Research Corporation (FMRC) in the late 1970s and early 1980s. (Nolan, 2000)

egress—a way out or exit. (NFC Online Glossary)

electrical fire—a fire involving energized electrical equipment. They are usually propagated by

electrical short circuits, faults, arcs, and sparks, and the equipment remains energized during the

fire event. Due to the possibility of electrical shock, nonconductive extinguishing agents, Class C

(carbon dioxide), must be used for fire control and suppression efforts. When the equipment is deenergized, Class A or B extinguishing agents may be used. (Nolan, 2000)
F-22

ember—a particle of solid material that emits radiant energy due to its temperature or the process

of combustion on its surface. (NFC Online Glossary)

emergency voice/alarm communication system—a system that provides dedicated manual or

automatic, or both, facilities for originating and distributing voice instructions, as well as alert and

evacuation signals pertaining to a fire emergency to the occupants of a building. 

(NFC Online Glossary)

emissivity—the ratio of radiant energy emitted by a surface to that emitted by a black body of the

same temperature (the property (0 to 1) that gives the fraction of being a perfect radiator).

emissive power—the total radiative power discharged from the surface of a fire per unit area (also

referred to as surface emissive power).

emissive power—the rate at which radiant energy is emitted by unit surface area of an object.

energy—a state of matter representative of its ability to do work or transfer heat.

energy balance—three modes of heat transfer (i.e., conduction, convection, and radiation) can be

combined by adding gains and losses to determine the temperature at some point. This

combination of energy gains and energy losses is called an energy balance. The exact form of the

energy balance will differ for each situation evaluated. 

entrainment—the process of air or gases being drawn into a fire, plume, or jet.

equivalent length—a length of pipe of a given diameter whose friction loss is equivalent to the

friction loss of a pipe of differing diameter.

equivalent fitting length—a length of straight pipe that has the same friction loss as a fitting where

the water changes direction.

evaporation—the process of gas molecules escaping from the surface of a liquid.

exit—the portion of the means of egress that leads from the interior of a building or structure to the

outside at ground level, or an area of refuge. (NFC Online Glossary)

exit access—any portion of an evacuation path that leads to an exit. (NFC Online Glossary)

exit discharge—that portion of a means of egress between the termination of the exit and the

exterior of the building at ground level. (NFC Online Glossary)

explosion—a sudden violent expansion or production of gases which may be accompanied by heat,

shock waves, and the disruption or enclosing of nearby structural materials.

exposed (cables/circuits /equipment/structures)—structures, systems and components (SSCs), that

are subject to the effects of fire and/or fire suppression activities. 

exposed (cables/circuits/equipment/structures)—SSC not provided with fire protection features

sufficient to satisfy Section III.G.2 of Appendix R or Position C.5.b of SRP 9.5.1.
F-23

exposure fire—a fire in a given area that involves either in situ or transient combustibles and is

external to any structures, systems, and components located in or adjacent to that same area. The

effects of such fire (e.g., smoke, heat, or ignition) can adversely affect those structures, systems,

and components important to safety. Thus, a fire involving one success path of safe shutdown

equipment may constitute an exposure fire for the redundant success path located in the same

area, and a fire involving combustibles other than either redundant success path may constitute an

exposure fire to both redundant trains in the same area. (Regulatory Guide 1.189)

exposure hazard—a structure at a location (15.24 m (50 ft) of another building and 9.3 m (100 ft )

2 2

or larger in area.

extinguish—to cause a material to cease burning; to completely control a fire so that no abnormal

heat of smoke remains, or to cause to cease burning, or completely put out a fire. (Nolan, 2000)

extinguish—to cause a material to cease burning; to completely control a fire so that no abnormal

heat or smoke remains. Fire extinguishment may be obtained by several methods: cooling, oxygen

depletion or removal, inhibition of chemical reaction, and flame removal (blowout).

extinguisher rating—the numerical rating given to an extinguisher which indicates the extinguishing

potential of the unit based on standardized tests developed by Underwriters' Laboratories, Inc. 

Extra large orifice (ELO) sprinkler—a fire suppression sprinkler for automatic sprinkler systems that

has an orifice size of 0.675 in. (1.59 cm). Standard sprinklers have an orifice size of 0.5 in. (1.27

cm). ELO sprinklers are used for hazards requiring a higher density of water application such as

those with a high fuel loading. (Nolan, 2000)

failsafe circuits—circuits designed in such a way that fire-induced faults will result in logic

actuation(s) to a desired, safe, mode which can not be overridden by any subsequent circuit

failures.

failure mode—the action of a device or system to revert to a specified state upon failure of the utility

power source that normally activates or controls the device or system. Failure modes are normally

specified as fail open (FO), fail closed (FC), or fail steady (FS) which will result is a fail to danger

arrangement.

fault—any undesired state of a component or system. A fault does not necessarily require failure

(for example, a pump may not start when required because its feeder breaker was inadvertently left

open. (IEEE Std. 100-1988)

fault—a partial or total local failure in the insulation or continuity of a conductor.

(IEEE Std. 100-1988)

fault—a physical condition that causes a device, a component or an element to fail to perform in

a required manner, for example a short-circuit, a broken wire, an intermittent connection. 

(IEEE Std.100-1988)
F-24

fault current—a current that flows from one conductor to ground or another conductor owing to an

abnormal connection (including an arc) between the two. (IEEE Std. 100-1988)

fault current—a current that results from the loss of insulation between conductors or between a

conductor and ground. (NEMA Std. ICS-1, 1988)

fire—the process of an advancing fire front: smoldering or flaming or an uncontrolled chemical

reaction producing light and sufficient energy.

fire—a processing entailing rapid oxidative, exothermic reactions in which part of the released

energy sustains the process.

fire—a rapid oxidation process with the evoluation of light and heat in varying intensities.

(NFC Online Glossary)

firebrand—a flaming or smoldering airborne object emerging from a fire, which can sometimes

ignite remote combustibles.

fire area—the portion of a building or plant that is separated from other areas by rated fire barriers

adequate for the fire hazards. (Regulatory Guide 1.189)

fire area boundaries—the term “fire area” as used in Appendix R means an area sufficiently

bounded to withstand the hazards associated with the area and, as necessary, to protect important

equipment within the area from a fire outside the area. In order to meet the regulation, fire area

boundaries need not be completely sealed floor-to-ceiling, wall-to-wall boundaries. However, all

unsealed openings should be identified and considered the evaluating the effectiveness of the

overall barrier. Where fire area boundaries are not wall-to-wall, floor-to-ceiling boundaries with all

penetrations sealed to the fire rating required of the boundaries, licensees must perform an

evaluation to assess the adequacy of fire boundaries in their plants to determine if the boundaries

will withstand the hazards associated with the area. This analysis must be performed by at least

a fire protection engineer and, if required, a systems engineer. 

(Generic Letter 86-10)

fire ball—a burning fuel-air cloud whose energy is emitted primarily in the form or radiant heat. The

inner core of the cloud consists almost completely of fuel, whereas the outer layer (where ignition

first occurs) consists of a flammable fuel-air mixture. As the buoyancy forces of hot gases

increases, the burning cloud tends to rise, expand, and assume a spherical shape.

fire barrier—components of construction (wall, floor, and their supports), including beams, joists,

columns, penetration seals or closures, fire doors, and fire dampers that are rated by approving

laboratories in hours of resistance to fire, that are used top prevent the spread of fire.

fire characteristics—a set of data that provides a description of a fire.

fire control—limiting the size of a fire by distribution of water so as to decrease the heat release rate

and pre-wet adjacent combustibles, while controlling ceiling gas temperatures to avoid structural

damage. (NFC Online Glossary)
F-25

fire control—the stage is firefighting whereby a fire incident is controlled and not allowed to escalate

in magnitude. Following fire control, suppression or extinction of the fire incident will occur. Fire

control limits the growth of a fire by pre-wetting adjacent combustibles and controlling ceiling gas

temperatures to prevent structural damage.

fire department connection—device that allows the fire department to pump water into a fire a fire

protection system from their trucks.

fire dynamics—fire dynamics is the scientific description of fire phenomena (e.g., ignition, flame

spread, burning, smoke spread) in quantitative terms. It encompasses chemistry, physics,

mathematics, fluid mechanics as well as heat and mass transfer.

fire dynamics—the interaction among the complex phenomena involved in a building fire.

fire endurance—the length of time that a structural element can resist fire either up to the point of

collapse, or alternatively, to the point when the deflection reaches a limiting value. (Nolan, 2000)

fire extinguishment—the complete suppression of a fire until there are no burning combustibles

material. (NFC Online Glossary)

fire extinguisher rating—a rating set forth in NFPA 10, Standard for Portable Fire Extinguishers.

This rating is identified on an extinguisher by number (e.g., 5, 20, 70), indicating relative

effectiveness, followed by a letter (e.g., A, B, C, or D) indicating the class or classes of fires for

which the extinguisher has been found to be effective. (NFC Online Glossary)

fire-fighting foam—a fire fighting medium that is created by adding a foaming agent to a liquid

(usually water).

fire growth potential—the potential size or intensity of a fire over a period of time based on the

available fuel and the fire’s configuration. (NFC Online Glossary)

fire growth rat—rate of change of the heat release rate. Some factors that affect the fire growth rate

are exposure, geometry, flame spread, and fire barrier. (NFC Online Glossary)

fire hazard—the existence of conditions that involve the necessary elements to initiate and support

combustion, including in situ or transient combustible materials, ignition sources (e.g., heat, sparks,

open flame), and an oxygen environment.

fire hazard analysis—an analysis used to evaluate the capability of a nuclear power plant to perform

safe shutdown functions and minimize radioactive releases to the environment in the event of a fire.

The analysis includes the following features (Regulatory Guide 1.189):

• Identification of fixed and transient fire hazards.

• Identification and evaluation of fire prevention and protection measures relative to the

identified hazards.

• Evaluation of the impact of fire in any plant area on the ability to safely shutdown the reactor

and maintain shutdown conditions, as well as to minimize and control the release of

radioactive material.
F-26

fire hazard analysis—a comprehensive assessment of the potential for a fire at any location to

ensure that the possibility of injury to people or damage to buildings, equipment, or the environment

is within acceptable limits. (NFC Online Glossary)

fire hydraulic—term for the science or study of water in motion (fluid mechanics) as applied to fire

protection application (firefighting, fire suppression, fixed water-based suppression systems etc.)

fire hydrant—a device that provides a water supply to fire department pumpers for use in combating

structure fires.

fire growth rate—the periodic increase in a fire, dependent on the ignition process, flame spread,

and mass burning rate over the area involved.

fire-induced fault—an electrical failure mode (e.g., hot short, open circuit, or short to ground) that

may result from circuit/cable exposure to the effects of fire (e.g., heat and smoke) and/or

subsequent fire suppression activities (e.g., water spray, hose streams ).

fire-induced vulnerability evaluation (FIVE)—five is a semi-quantitative method of fire risk and

hazard analysis for screening purposes. The methodology has been used to perform risk-based

fire-induced vulnerability evaluations for NPPs. This technique was developed by the Electric

Power Research Institute (EPRI) under the guidance of the Severe Accident Working Group of the

Nuclear Management and Resources Council (NUMARC) and the industry’s experts, for the

purpose of addressing the fire portion of licensee’s Individual Plant Examination of External Events

(IPEEE) studies.

fire load—the fire load for an enclosure is a measure of the total energy released by the combustion

of all combustible materials in the enclosure. It is assigned the symbol W, and is given in joules

(J).

fire loading—the amount of combustible present in a given area, expressed in kJ/m (Btu/ft ). 2 2

(NFC Online Glossary)

fire load density—the fire load density is the fire load per unit area. The fire load density is

assigned the symbol Q” and is given in J/m . Some times the fire load is given is per unit floor area 2

of the enclosure or some times in terms of the total enclosure surface area.

fire model—a physical or mathematical procedure that incorporates engineering and scientific

principles in the analysis of fire and fire effects to simulate or predict fire characteristics and

conditions of the fire environment. 

fire modeling—fire modeling can normally be considered as the predication of fire characteristics

by the use of a mathematical method which is expressed as a computer program.

fire performance—the response of a material or product to a source of heat or flame under

controlled fire conditions. Fire performance includes: ease of ignition, flame spread, smoke

generation, fire resistance and toxicity of smoke.
F-27

fire plume—a buoyant column of fire gases and smoke rising above, usually with flames in the lower

portion. In a confined area a fire plume rises almost vertically. In an outside, unconfined area the

configuration of a fire plume is affected by ambient conditions (wind, temperature etc.)

fire point—the minimum temperature to which a liquid must be heated in a standardized apparatus,

so that sustained combustion results when a small pilot flame is applied, as long as the liquid is at

normal atmospheric pressure.

fire point—the lowest temperature at which flaming can be sustained at the liquid’s surface.

fireproofing—a common industry term used to denote materials or methods of construction that

provide fire resistance for a defined fire exposure and specific time.

fireproof—common trade name for materials used to provide resistance to a fire exposure.

Essentially nothing is fireproof, but some materials are resistant to effects of fire (heat flame etc.)

for limited periods.

fire prevention code—a set of requirements intended to ensure that, following construction, building,

buildings are equipped, operated and maintained to provide an acceptable level of protection from

potential hazards created by fires or explosions.

fire prevention research engineer—conducts research to determine cause and methods of

preventing fires and prepares educational materials concerning fire prevention for insurance

companies, performing duties as described under Research Engineer. (“Dictionary of Occupational

Titles,” Volume 1, 14 Edition, U.S. Department of Labor Employment and Training Administration, th

1991.)

fire protection engineer—advises and assists private and public organization and military services

for purpose of safeguarding life and property against fire, explosion, and related hazards. Make

studies of industrial, mercantile. And public buildings, homes, and other property before and after

construction, considering factors, such as fire resistance of construction, usage or contents of

buildings, water supplies and water delivery, and egress facilities. Designs or recommends

materials or equipment, such as structural components protection, fire detection equipment, alarm

systems, fire extinguishing devices and systems, and advises on location, handling, installation, and

maintenance. Recommends materials, equipment, or methods for alleviation of conditions

conductive to fire. Devices fire protection programs, and organizes and trains personnel to carry

out such programs. May evaluate fire departments and adequacy of laws, ordinances, and

regulations affecting fire prevention or fire safety. Conducts research and test on fire retardants

and fire safety of materials and devices and to determine fire causes and methods of fire

prevention. May determine fire causes and methods of fire prevention. May teach courses on fire

prevention and protection at accredited educational institutions. May advise and plan for prevention

of destruction by fire, wind, water, or other causes of damage. (“Dictionary of Occupational Titles,”

Volume 1, 14 Edition, U.S. Department of Labor Employment and Training Administration, 1991.) th

fire protection rating—a designation of fire resistance duration for a material or assembly when

exposed to standard test conditions, having met all acceptance criteria. (Nolan, 2000)
F-28

fire resistance—the ability of an element of building construction, component, or structure to fulfill,

for a stated period of time, the required load-bearing functions, integrity, thermal insulation, or other

expected duty specified in a standard fire-resistance test.

fire resistive construction—construction in which the structural members, including walls, columns,

floors, and roofs are noncombustible or limited-combustible materials, and have fire resistance

rating not less than those specified in NFPA 220; fire resistive construction has more ability to resist

structural damage from fire than any other construction type.

fire-retardant coating—a coating that reduces that flame spread of combustible materials surfaces

to which it is applied, by at least 50 percent or to a flame spread classification value of 75 or less,

whichever is the lesser value, and smoke developed rating not exceeding 200. (Nolan, 2000)

fire-retardant material—means materials that has been coated or treated with chemical, paints, or

other materials that designed to reduce the combustibility of the treated material. The retardants

are intended to make the material ignite less readily or burn more slowly, once ignited.

fire risk—refers to the combination of the probability of a given fire event occurring and the

estimated consequences of the event should it occur. (Regulatory Guide 1.189)

fire-rated cable—electrical cable with a fire resistance rating on maintaining functionality when

exposed to fire tests.

fire-resistant cable—electrical cable that has been tested and found resistant to the spread of

flames.

fire resistance rating —the time that a particular construction will withstand a standard fire exposure

in hours as determined by ASTM E119.

fire resistance rating—the time that materials or assemblies have withstood a fire exposure as

established in accordance with the test procedures of NFPA 251 and ASTM E119. 

(Regulatory Guide 1.189)

fire-resistive joint system—see seismic gap penetration seal.

fire pump—a device that provides the required water flow and pressure for a fire protection system.

fire scenario—a set of conditions that defines the development of fire and the spread of combustion

products throughout a building or part of a building.

fire separation—a fire-resistive barrier to restrict the spread of fire, provided in a horizontal or

vertical orientation.

fire severity—the maximum effects that can be caused by a fire event. Usually described in terms

of temperature and duration, and may be used to described the potential for fire destruction for a

particular location. The rate of heat release has also been accepted as a guide of fire severity.

(Nolan, 2000)
F-29

fire signature—a property of fire (temperature, smoke concentration, etc.) that is used to detect the

presence of fire.

fire spread—the process of an advancing flame front through smoldering or flaming.

fire stop—a feature to the construction that prevents fire propagation along the length of cables or

prevents spreading of fire to nearby combustibles within a given fire area or fire zone.

fire suppression—control and extinguishing of fire (fire-fighting). Manual fire suppression is the use

of hoses, portable extinguishers, or manually actuated fixed systems by plant personnel. Automatic

fire suppression is the use of automatically actuated systems such as water, Halon, or carbon

dioxide systems (Regulatory Guide 1.189). Firefighting activity concerned with controlling and

reducing a fire prior to its actual extinguishment. Fire suppression is generally taken as the sharp

reduction of the rate of heat release of a fire and the prevention of its growth. Fire extinguishment

activities encompass the actual direct fire extinction process.

fire suppression—all the work of confining and extinguishing wildland fires.

(NFC Online Glossary)

fire suppression—sharply reducing the heat release rate of a fire and preventing its regrowth by

means of direct and sufficient application of water through the fire plume to the burning fuel surface.

(NFC Online Glossary)

fire suppression—the activities involved in controlling and extinguishing fires. Fire suppression

shall include all activities performed at the scene of a fire incident or training exercise that expose

fire department members to the dangers of heat, flame, smoke, and other products of combustion,

explosion, or structural collapse. (NFC Online Glossary)

fire suppression—control and extinguishing of fires (firefighting). Manual fire suppression employs

the use of hoses, portable extinguishers, or manually actuated fixed systems by plant personnel.

Automatic fire suppression is the use of automatically actuated fixed systems such as water, Halon,

or carbon dioxide systems. (Regulatory Guide 1.189).

fire suppression—actions taken with the intend to control the growth of a fire.

fire suppression impacts—the susceptibility of structures, systems and components and operations

response to suppressant damage (due to discharge or rupture) (NFPA 805).

fire triangle—a concept describing fire as consisting of three ingredients: fuel, oxygen, and energy.

fire tetrahedron—a schematic representation of fire in which the four elements required to initiate

and maintain fire (fuel, oxidant, heat and chain reactions) are depicted as the four corners of a

tetrahedron.

fire watch—individuals responsible for providing additional (e.g., during hot work) or compensatory

(e.g., for system impairments) coverage of plant activities or areas for the purposes of detecting

fires or for identifying activities and conditions that present fire hazard. The individuals should be

trained in identifying conditions or activities that present potential fire hazards, as well as the use

of fire extinguishers and the proper notification procedures. (Regulatory Guide 1.189)
F-30

fire zones—a subdivisions of fire areas (Regulatory Guide 1.189)

fixed fire suppression system—a total flooding or local application system consisting of a fixed

supply of extinguishing agent permanently connected for fixed agent distribution to fixed nozzles

that are arranged to discharged an extinguishing agent in an enclosure (total flooding), directly onto

a hazard (local application), or a combination of both; or an automatic sprinkler system.

(NFC Online Glossary)

fixed fire suppression system—a fire suppression system that provides local application, area

coverage, or total flooding protection. It consists of a fixed supply of extinguishing agent,

permanently connected distribution piping, and fixed nozzles that are arranged to discharge an

extinguishing agent into an enclosure (total flooding), directly onto a hazard (local application), over

an entire area (area coverage), or a combination of application.

FIVE—a fire-induced vulnerability evaluation - a quantitative screening technique sponsored by

EPRI under the guidance of the Severe Accident Working Group of the Nuclear Management and

Resources Council (NUMARC) and the industry’s experts, for the purpose of addressing the fire

portion of licensees’ IPEEE studies.

fire PRA methodology—the set of procedures, based on probabilistic risk analysis, for estimating

core damage frequency due to fire events. 

fire zones—subdivisions of fire areas. 

flare—a flame condition of a fire in which burning occurs with an unsteady flame.

flame arrester—a device installed in a pipe or duct to prevent the passage of smoke.

flame arrester—a device that prevents the transmission of a flame through a flammable gas/air

mixture by quenching the flame on the surface of an array of small passages through which the

flame must pass. The emerging gases are sufficiently cooled to prevent ignition on the protected

side. (NFC Online Glossary)

flame burning velocity—the burning velocity of a laminar flame under stated conditions of

composition, temperature, and pressure of the unburned gas. (NFC Online Glossary)

flame detector—a detector that is activated by electromagnetic radiation emitted by flames.

flame height—the vertical measurement of the combustion region.

flame speed—the speed of a flame front relative to a fixed reference point. It is dependent on the

turbulence, the equipment geometry, and the fundamental burning velocity. 
F-31

flame spread—the increase in the perimeter of a fire. Flame spread depends on orientation and

the surrounding fluid flow. It can be associated with solids, liquids, forest fuels, smoldering, and

gas-phase propagation for premixed systems. Flame spread is influenced by gravity (flame

buoyancy) and wind effects. Relative flame spread speeds are indicated below (Nolan, 2000):

Phenomenon Speed (cm/sec)

smoldering 10 to 10 -3 -2

downward or horizontal spread (thick solids) 10-1

upward spread (thick solids) 1 to102

wind-driven spread through forest debris 1 to 30

horizontal spread on liquids 1 to 102

laminar deflagration 10 to 102

detonation ~105

flame spread index—a relative performance of fire travel over the surface of a material when tested

in accordance with the provisions of NFPA 255, Standard method of Test of Surface Burning

Characteristics of Building Materials. (Nolan, 2000)

flame spread rating—flame spread rating is a numerical classification determined by the test

method ASTM E84, which indexes the relative burning behavior of a material by quantifying the

spread of flame of at test specimen. The surface burning characteristic of a material is not a

measure of resistance to fire exposure. (NFC Online Glossary)

flammable limits—the minimum and maximum concentration of combustible material in a

homogeneous mixture with a gaseous oxidizer that will propagate a flame.

flammable—capable of being ignited.

flammable liquid—as defined by the most fire safety codes (NFPA 30, “Flammable Combustible

Liquids Code”), generally a flammable liquid is any liquid that has a closed-cup flash point below

37.8 °C (100 °F). Flash points are determined by procedures and apparatus set fort in ASTM D56,

“Standard Method of Test for Flash Point by the Tag Closed Tester.”

• Class I Flammable Liquid—any liquid that has a defined closed-cup flash point below

37.8 °C (100 °F) and a Reid vapor pressure not exceeding 40 psi (2,068.6 mm Hg) at

37.8 °C (100 °F), as determined by the ASTM D323, “Standard Method of Test for Vapor

Pressure of Petroleum Products (Reid Method)”.

• Class I liquids are further sub-classified into A and B as follows:

• Class IA flammable liquids—liquids that have a defined flash point below 22.8 °C (73 °F)

and boiling points below 37.7 °C (100 °F).

• Class IB flammable liquids—liquids that have a defined flash point below 22.8 °C (73 °F)

and boiling points at or above 37.7 °C (100 °F).

• Class II flammable liquids—any liquid that has a flash point at or above 37.8 °F (100 °F) and

below 60 °C (140 °F).

• Class IIIA flammable liquids—any liquid that has a flash point at or 60 °C (140 °F), but

below 93 °C (200 °F).

• Class IIIB flammable liquids—any liquid that has a flash point at or 93 °C (200 °F).
F-32

flame temperature—most open flames of any type produce a flame temperature in the region of

1,093 °C 4 2 (2,000 °F). The hottest burning substance is carbon subnitride (C N ), which at one

atmospheric pressure can produce a flame calculated to reach 4,988 °C (9,010 °F). (Nolan, 2000)

flash—a quick spreading flame or momentary intense outburst of radiant heat. It may also be used

to refer to a spark or intense light of short duration.

flash fire—a fire that spreads rapidly through a diffuse fuel, such as dust, gas, or the vapors of an

ignitable liquid, without the production of damaging pressure. (NFC Online Glossary)

flash point—the minimum temperature to which a liquid must be heated in a standardize apparatus,

so that a transient flame moves over the liquid when a small pilot flame is applied.

(NFC Online Glossary)

flash point—the flash point of a liquid is the temperature at which the vapor and air mixture laying

just above its vaporizing surface is capable of just supporting a momentary flashing propagation

of a flame prompted by a quick sweep of small gas pilot flame near its surface, hence the term flash

point. The flash point is mainly applied to a liquid. The flash point of liquid is one of its

characteristics that normally determines the amount of fire safety features requires for its handling,

storage and transport.

flashover—the transition from fire growth period to the full developed stage in the enclosure fire

development that is the demarcation point between two stages of a compartment fire, pre-flashover

and post-flashover. Flashover is a phenomenon which defines the point in a compartment fire

where all combustibles in the compartment are involved and flames appears to fill the entire

volume. Gas temperatures of 300 to 650 °C (572 to 1,202 °F) have been associated with the onset

of flashover, although temperatures of 500 to 600 °C (932 to 1,112 °F) are more widely used.

flashover—when a fire in a compartment is allowed to grow without intervention, assuming sufficient

fuel in the burning item, temperatures in the hot upper lager will increase, with increasing radiant

heat flux to all objects in the room. If a critical level of heat flux is reached, all exposed combustible

items in the room will begin to burn, leading to a rapid increase in both heat release rate and

temperatures. This transition is “flashover”. The fire is then referred to as “post-flashover fire”, a

“fully developed fire” or a fire which has reached “full room involvement”.

flashover—the formal definition of flashover, from International Standards Organization (ISO), is

given as, “the rapid transition to a state of total surface involvement in a fire of combustion material

within an enclosure”. Flashover is the term given to the relatively abrupt change from a localized

fire to the complete involvement of all combustibles within a compartment. This is from ISO,

“Glossary of Fire Terms and Definitions,” ISO/CD 13943, International Standards Organization,

Geneva, 1996.

flash vaporization—the instantaneous vaporization of some or all a liquid whose temperature is

above its atmospheric boiling point when its pressure is suddenly reduced to atmosphere.

flow hydrant—a hydrant selected to measure the water flow available from the water supply.

flux—pertains to mass or heat flow rates per unit area.
F-33

forced flow—refers to air flow produced by wind or a fan.

free-burning—burning in open-air.

free of fire damage—the structure, system, or component under consideration is capable of

performing its intended function during and after the postulated fire, as needed without repair

(Regulatory Guide 1.189). In promulgating Appendix R, the Commission has provided methods

acceptable for assuring that necessary structures, systems and components are free of fire damage

(see Section III.G.2a, b and c), that is, the structure, system or component under consideration is

capable of performing its intended function during and after the postulated fire, as needed.

Licensees seeking exemptions from Section III.G.2 must show that the alternative proposed

provides reasonable assurance that this criterion is met. The term “damage by fire” also includes

damage to equipment from the normal or inadvertent operation of fire suppression systems.

(Generic Letter 86-10).

Note: Section III.G.2 of Appendix R and Position C.5.b of Standard Review Plan (SRP) Section

9.5.1 establish fire protection features necessary to ensure that systems needed to achieve and

maintain hot shutdown conditions remain free of fire damage.

fuel-controlled or fuel-limited fire—after ignition and during the initial fire growth stage, the fire is

said to be fuel-controlled, since in the initial stages there is sufficient oxygen available for

combustion and the growth of the fire entirely depends on the characteristics of the fuel and its

geometry. The fire can also be fuel-controlled in later stages.

fuel lean—description of fuel burning in an excess supply of air.

fuel-limited—state of a compartment fire where the air supply is sufficient to maintain combustion.

fully developed—state of a compartment fire during which the flames fill the room involving all the

combustibles, or the state of maximum possible energy release in a room fire.

fundamental burning velocity—the burning velocity of a laminar flame under stated conditions of

composition, temperature, and pressure of the unburned gas.

fuse—a device that protects a circuit by fusing open its current responsive element when an

overcurrent or short-circuit current passes through it. (IEEE Std. 100-1988). 

fuse—a protective device that opens by the melting of a current-sensitive element during specified

overcurrent conditions (NEMA Std. FU-1 1986).

fuse current rating—the ac or dc ampere rating which the fuse is capable of carrying continuously

under specified conditions. (NEMA Std. FU-1 1986)

fuse voltage rating—the maximum rms ac voltage or the maximum dc voltage at which the fuse is

designed to operate. (NEMA Std. FU-1 1986)

fusible link—a system of levers and links held together with a metal alloy which melts at a

predetermined temperature.
F-34

fusible link—a connecting link of a low-melting alloy that holds an automatic sprinkler head in the

closed position and melts at a predetermined temperature; it may also be used to hold a fire door

or fire damper in the open position.

gas combustible—gas that is capable of being ignited and burned, such as hydrogen, methane,

propane, etc.

gas sensing detector—a detector activates when a critical concentration of some gaseous product

of combustion is reached.

generic issue (GI)—a concern that may affect the design, construction, or operation of all, several,

or a class or nuclear power plants, which either does not affect safe operation of the plant or the

safety significance of the issue has not yet been determined.

generic safety issue (GSI)—according to the NUREG-0933, “A Prioritization of Generic Safety

Issues,” a GSI is a safety concern that may affect the design, construction, or operation of all,

several, or a class of nuclear power plants, and may have the potential for safety improvements and

promulgation of new or revised requirements or guidance. 

glove box—a sealed enclosure in which items inside the box are handled exclusively using long

rubber or neoprene gloves sealed to ports in the walls of the enclosure. The operator places his

or her hands and forearms into the gloves from the room outside of the box in order to maintain

physical separated from the glove box environment. This allows the operator to retain the ability

to manipulate items inside the box with relative freedom while viewing the operation through a

window. (NFC Online Glossary)

glowing combustion—luminous burning of solid material without a visible flame. A stage in the

ignition of a solid material that occurs before sufficient volatile fuel has evolved to sustain a gasphase flame. (NFC Online Glossary)

gravity—the force of mutual attraction between masses. 

gravity—the force that causes a body to accelerate while falling, usually expressed as 32.2 ft/sec2

(9.81 m/sec ). 2

ground—a conducting connection, whether intentional or accidental, by which an electric circuit or

equipment is connected to the earth, or to some conducting body of relatively large extent that

serves in place of the earth. (IEEE Std. 100-1988)

grounded circuit—a circuit in which one conductor or point (usually the neutral conductor or neutral

point of transformer or generator windings) is intentionally grounded, either solidly or through a noninterrupting current limiting grounding device. (IEEE Std.100-1988)

Halon—any one of several halogenated hydrocarbon compounds, two of which

(bromotriflioromethane and bromochlorodifuoromethane) are commonly used as extinguishing

agents; they are inert to almost all chemicals, and resistant to both high and low temperatures. 
F-35

Halon—as employed in the fire protection industry, a gaseous fire suppression agent. Halon is an

acronym for halogenated hydrocarbons, commonly bromotriflioromethane Halon 1301) and

bromochlorodifuoromethane (Halon 1201). Consider obsolete for fire protection purposes due to

a possible environmental impact to the Earth’s atmosphere ozone layer and beginning to be phased

out or eliminated. In order for a Halon fire suppression system to be an effective fire suppression,

the system must provide a very rapid response and be completely discharged while the fire is in its

incipient stages (i.e., the fire is still controllable). The system discharge enough of the agent to

effectively actively the chemical chain breaking mechanism of the diffusion flame combustion

process and that discharge be contained in the area for a long enough period for this to be

accomplished.

hazard—a possible source of danger that can initiate or cause undesirable consequences if

uncontrolled.

hazard—hazard is a chemical or physical condition that has the potential for causing damage to

people, property, or the environment. An example would be flammable liquids or explosive gases

or dusts used in the process or in storage.

hazardous material—a substance that, upon release, has the potential of causing harm to people,

property, or the environment. 

HAZOP—an acronym for the hazard and operability study in which the hazards and operability of

a system are identified and analyzed in a systematic manner to determine if adequate safe guards

are in place. (Nolan, 2000)

heat—energy transfer due to temperature difference.

heat capacity—the energy that must be added to a unit mass of a substance in order to rise its

temperature by 1 °C (34 °F) (as long as no phase change occurs). Also called thermal capacity.

Heat collector plate or Canopy—a covering provided over a heat detector or automatic sprinkler

placed in the open, to trap and collect updrafts of heat from a fire incident to aid in its detection or

sprinkler activation. They commonly consist of a sheet of steel (Nolan, 2000). Heat collectors were

intended to reduce the time a fire takes to activate sprinklers located too far below the ceiling.

When sprinklers are too far below the ceiling, most of the heat energy rises past the sprinklers and

heat collectors and the sprinklers are not activated. Locating the sprinkler close to the ceiling

ensures that the sprinkler will be in the hot gas layer, minimizing activation time and enabling the

sprinkler to provide a fully developed water spray pattern to control the fire. In addition, the water

from the sprinkler cools the upper gas layer (preventing flashover conditions) and cools the

structural steel supports of the compartment boundaries (preventing structural collapse).

heat flux—the rate of heat transfer per unit area that is normal to the direction of heat flow. It is a

total of heat transmitted by radiation, conduction, and convection. A radiant heat flux of 1 kW/m2

(312.5 Btu/ft -hr) (that is, direct sunlight) will be felt as pain to exposed skin. A radiant heat of 4 2

kW/m (1,250 Btu/ft -hr) will cause a burn on exposed skin. A heat flux density of 10–20 kW/m 2 2 2

(3,125–6,250 Btu/ft -hr) may cause objects to ignite, and a heat flux density of 37.8 kW/m (11,813 2 2

Btu/ft -hr) will cause major damage. Heat flux may also be called heat flow rate. (Nolan, 2000) 2

heat of combustion—the energy released by the fire per unit mass of fuel burned. 

(Quintiere, 1998)
F-36

heat of condensation—the energy released when a unit mass of vapor condenses to a liquid.

(Friedman, 1998)

heat of decomposition—the amount of heat released during a chemical decomposition reaction.

(Nolan, 2000)

heat of fusion—the energy absorbed when a unit mass of a solid melts. (Friedman, 1998)

heat of gasification—energy required to produce a unit mass of fuel vapor from a solid or liquid.

(Quintiere, 1998)

heat of solidification—the energy released when a unit mass of a liquid solidifies. (Friedman, 1998)

heat of sublimation—the energy absorbed when a unit mass of a solid gasifies directly, without

forming a liquid and without chemical change. (Friedman, 1998)

heat of vaporization—the energy absorbed when a unit mass of liquid vaporizes. (Friedman, 1998)

heat release rate—the rate at which heat energy is generated by burning. The heat release rate

of a fuel is related to its chemistry, physical form, and availability of oxidant and is expressed as kW

(kJ/sec) or Btu/sec. (Nolan, 2000)

heat resistance—the property of a foam to withstand exposure to high heat fluxes without loss of

stability. (NFC Online Glossary)

heat transfer—the branch of physics dealing with the calculation of the rate at which thermal energy

(heat) moves from a hotter to a cooler region or the transport of energy from a high-to a lowtemperature object.

high/low pressure interface—reactor coolant boundary valves whose spurious operation due to fire

could: (a) potentially rupture downstream piping on an interfacing system, or (b) result in a loss of

reactor coolant inventory in excess of the available makeup capability. 

high-impedance fault—an electrical fault of a value that is below the trip point of the breaker on

each individual circuit. (Generic Letter 86-10)

high-impedance fault—a circuit fault condition resulting in a short to ground, or conductor to

conductor hot short, where residual resistance in the faulted connection maintains the fault current

level below the component’s circuit breaker long-term setpoint. (Regulatory Guide 1.189)

horizontal exit—an exit from one building to another on approximately the same level; or a passage

through or around a rated wall or partition that affords protection from fire or smoke coming from

the area from which escape is made. (NFC Online Glossary)
F-37

hot short—an electric cable failure mode, resulting from a fire, which involves making an electrical

connection between a conductor with power and a conductor that does not currently have power,

without a simultaneous short to ground or open-circuit condition. Such failure might, for example,

simulate the closing of a control switch, cause errors in an instrument reading, or result in the

application of power to an unpowered circuit. ndividual conductors of the same or different cables

come in contact with each other and may result in an impressed voltage or current on the circuit

being analyzed. (Regulatory Guide 1.189)

Clarification: The term “hot short” is used to describe a specific type of short circuit fault condition

between energized and de-energized conductors. Should a de-energized conductor come in

electrical contact with an energized conductor (or other external source), the voltage, current or

signal being carried by the energized conductor(or source) would be impressed onto one or more

of the de-energized conductors.

hot work—activities that involve the use of heat, sparks, or open flame such as cutting, welding, and

grinding. (Regulatory Guide 1.189)

humidity—the property of the water-air mixture that measure the amount of water present relative

to the equilibrium concentration.

hybrid mixture—a mixture of a combustible gas with either a combustible dust or combustible mist.

hyperthermia—heat stress.

hypergolic—property of a material which describes its ability to spontaneously ignite or explode

upon contact with an oxidizing agent.

Ignition process—ignition is broadly defined as the initiation of the chemical process of combustion

(burning) in any fuel. In most fire protection problems, ignition involves both a heat source and

target fuel. A burning wastebasket can be an ignition source for a nearby chair. The burning chair

subsequently can be ignition source for another fuel.

In an otherwise free-free environment, the first unwanted burning is the initial ignition, and the initial

heat source is called an igniter.

In the environments where gases, vapors, or dust are present, the initial ignition may yield

combustion fast enough to generate a pressure or shock wave. This type of sudden over-pressure

requires different fire defense than spread from combustible to combustible without a pressure

wave.

ignition temperature—the surface temperature needed to cause ignition in solids. (Quintiere, 1997)

ignition temperature—temperature at which an element or compound will catch fire in air

(atmospheric oxygen).

impairment—the degradation of a fire protection system or feature that adversely affects the ability

to the system or feature to perform its intended function. (Regulatory Guide 1.189)

impulse—a measure that can be used to define the ability of a blast wave to do damage. It is

calculated by the integration of the pressure-time curve.
F-38

important to safety—nuclear power plant structures, systems, and components “important to safety”

are those required to provide reasonable assurance that the facility can be operated without undue

risk to the health and safety of the public. (Regulatory Guide 1.189)

incipient stage—refers to the severity of a fire where the progression is in early stage and has not

developed beyond that which can be extinguished using portable fire extinguishers or handlines

flowing up to 125 gpm (473 L/min). A fire is considered to be beyond the incipient stage when the

use of thermal protective clothing or self-contained breathing apparatus is required or an industrial

fire brigade member is required to crawl on the ground or floor to stay below smoke and heat.

(NFC Online Glossary)

incipient stage fire—a fire which is in the initial or beginning stage and which can be controlled or

extinguished by portable fire extinguishers, Class II standpipe or small hose systems without the

need for protective clothing or breathing apparatus. 

incomplete combustion—a combustion process that does not go the most stable species such as

H2 2 O and CO . (Quintiere, 1997)

inflammable—not a permissible word, because it introduces confusion as to whether flammable or

nonflammable is meant. (Friedman, 1998)

Inflammable—identical meaning as flammable, however the prefix “in” indicates a negative in many

words and can cause confusion, therefore the use of flammable is preferred over inflammable.

(Nolan, 2000)

indicating appliance—any audible or visible signal employed to indicate a fire, supervisory, or

trouble condition. Example of audible signal appliances are bells, horns, sirens, electronic horns,

buzzers, and chimes. A visible indicators consists of a lamp, target, meter deflection, or equivalent.

indicating appliance circuit—a circuit or path directly connected to an indicating deflection, or

equivalent.

inert gas—gases, such as carbon dioxide or nitrogen, that will not support combustion.

inert gas agents—an agents that contains one or more inert gases, such as helium, neon, argon,

nitrogen, and carbon dioxide. (NFC Online Glossary)

inerting—the process of removing an oxidizer (usually air or oxygen) to prevent a combustion

process from occurring normally accomplished by purging.

inerting—adding an agent within an enclosure to reduce a flammable concentration of gas or vapor.

initiating device (appliance)—a manually or automatically operated device, the normal intended

operation of which results in a fire alarm or supervisory signal indication from the control unit.

Example of alarm signal indicating devices are thermostats, manual boxes, smoke detectors, and

water flow switches. Examples of supervisory signal initiating devices are water level indicators

sprinklers system, valve position switches, pressure supervisory transmitters, and water

temperature switches.
F-39

individual plant examination (IPE)—an evaluation to identify any plant-specific vulnerabilities to

severe accidents initiated by internal events, including flooding, during full power operation.

(Generic Letter 88-20 has requested each licensee of a U.S. power plant to perform such

evaluation for its plant(s).

individual plant examination of external events (IPEEE)—an evaluation to identify any plant-specific

vulnerabilities to severe accidents initiated by external events during full power operation. [Generic

Letter 88-20, Supplement 4, has requested each licensee of a U.S. power plant to perform such

evaluation for its plant(s).]

internal fire—a fire initiated anywhere within the plant boundaries, including both areas within plant

structure and buildings, and contiguous outdoor areas such as the electrical switchyard and

transformer areas.

inter-cable fault—a fault between conductors of two or more separate cables.

inter-cable fault—a fault between two or more conductors within a single multi-conductor cable.

Interlock—a device actuated by the operation of some other device with which it is directly

associated to govern succeeding operations of the same or allied devices. Note: Interlocks may be

either electrical or mechanical. (IEEE Std.100-1988)

interrupting device—a breaker, fuse, or similar device installed in an electrical circuit to isolate the

circuit (or a portion of the circuit) from the remainder of the system in the event of an overcurrent

or fault downstream of the interrupting device. (Regulatory Guide 1.189)

isolating device/isolation device—a device in a circuit which prevents malfunctions in one section

of the circuit from causing unacceptable influences in other sections of the circuit or other circuits.

(IEEE Std. 100-1988; Regulatory Guide 1.189)

isolation transfer switch—a device used to provide electrical isolation from the fire affected area and

transfer control of equipment from the main control room to the local control station (alternate

shutdown panel).

insulated conductor—a conductor covered with a dielectric(other than air) having a rated insulating

strength equal to or greater than the voltage of the circuit in which it is used. (IEEE Std. 100-1988).

insulation (cable, conductor)—that which is relied on to insulate the conductor or other conductors

or conducting parts from ground. (IEEE Std. 100-1988)

intumescent coating—a protective chemical coating, which, when heated, internally generates

gases and expands, resulting in a thermally insulating crust that contains cavities.

in situ combustibles—combustibles materials that constitute part of the construction, fabrication,

or installation of plant structure, systems, and components and as such are fixed in place.

irritants—toxicant that irritate the eyes, upper respiratory tract and/or lungs.
F-40

irritant gases—acid gases and other hydrocarbon byproducts that can cause pain on contact or

inhalation.

jet—a discharge pressurized liquid, vapor, or gas into free space from an orifice, the momentum

of which induces the surrounding atmosphere to mix with the discharged material.

jet fire—combustion occurring at the release of liquid, vapor, or gas under pressure from a leakage

point (orifice), the momentum of which causes entrainment of the surrounding atmosphere. The

jet fire has a high heat flux, turbulent flame, and capability of eroding the material it impacts.

jet flame—flame due to high velocity fuel supply.

K-factor—coefficient specified for individual sprinklers based on their orifice design and used for

hydraulic calculations of the sprinkler system. K-factors are determined by the design and

manufacturer of the sprinkler head. (Nolan, 2000) 

K-factor—the thermal conductivity coefficient of materials. It is a measurement in standard terms

of the amount of heat conducted per the thickness of the material per the degree of temperature.

Kelvin (K)—absolute Celsius temperature, 273 + °C.

laminar—refers to orderly, unfluctuating fluid motion. (Quintiere, 1997)

latent heat—the characteristic amount of energy absorbed or released by a substance during a

change in its physical state that occurs without changing its temperature. The latent heat

associated with melting a solid or freezing a liquid is called the heat of fusion; that associated with

vaporizing a liquid or a solid or condensing a vapor is called the heat of vaporization. (Nolan, 2000)

leakage current (Insulation)—the current that flows through or across the surface of insulation and

defines the insulation resistance at the specified direct current potential (IEEE Std. 100-1988).

lean mixture—a mixture of flammable gas or vapor and air in which the fuel concentration is below

of fuel’s lower limit of flammability.

lean mixture—a mixture of air and gas that contains too much air for the amount of gas present to

cause an explosion and is thus below the lower flammable limit.

limited sprinkler system—an automatic sprinkler system that is limited to a single fire area and

consists of not more than twenty sprinklers.

line fire—elongated fires on a horizontal fuel surface. (Nolan, 2000)

listed—equipment or materials included on a list published by a recognized testing laboratory,

inspection agency, or other organization concerned with product evaluation that maintains periodic

inspection of production of listed equipment or materials, and whose listing states that certain

specific equipment or materials meet nationally recognized standards and have been tested and

found suitable for use in a specific manner. (Regulatory Guide 1.189, NFC Online Glossary)
F-41

local control—operation of shutdown equipment using remote controls (e.g., control switches)

specifically designed for this purpose from a location other than the main control room.

local control station—a control panel located in the plant which allows operation and monitoring of

plant equipment from outside of the main control room. For post-fire safe shutdown control

functions and monitoring variables on these panels must be independent (physically and

electrically)from those in the main control room.

local operation—manipulation of plant equipment from a location outside of the main control room.

For example, manual operation of the circuit breakers or turning the handwheel on the valve to

change its position.

load breaker—a circuit breaker that is located on the load side of a power source. Synonym: branch

breaker.

LOI—the limiting oxygen index, a characteristic of solid combustibles measured in a standards

appa 2 2 ratus in which the O /N ratio of the atmosphere is varied, to provide a measure of relative

flammability. Also called oxygen index (OI).

lower flammability limit—the lowest concentration of fuel in air at normal temperature and pressure

that can support flame propagation is known as the lower flammability limit (LFL) or lower explosive

limit (LEL).

lowe flammability limit—the lowest concentration of a vapor/air mixture which can be ignited by a

pilot. 

manual action—physical manipulation (operation) of equipment when local or remote controls are

no longer available of a plant component such as a valve, switch or circuit breaker.

manual valve—a valve that does not have the capability of being manipulated remotely.

manually operated valve—term used to denote a valve credited in the SSA or shutdown procedures

for being manually manipulated.

Note: A manually operated valve may be a manual valve or a remotely operated valve (e.g., MOV)

that has its power and control capability disabled or removed.

mass burning flux—burning rate per unit area. (Quintiere, 1997)

mass loss rate—the mass of fuel vaporized but not necessarily burned per unit time. 

(Quintiere, 1998)

mass optical density—a normalized value of the optical density of a smoke cloud, which is intended

to be independent of measuring apparatus.

material safety data sheets—a document, prepared in accordance with DOL 29 CFR, that contains

information regarding the physical and health hazards associated with a given product or substance

and a recommended emergency action.

means of egress—a safe, continuous, and unobstructed way of travel out of any building or

structure; this include the exit access, exit, and exit discharge. 
F-42

model—a model of anything is, simply, a systematic representation of that thing. For example, we

can have: thought models (or conceptual models), scale models, and mathematical models. These

three examples are probably the main representation which are used by scientists. A thought or

conceptual model is simply a proposed schema explaining how something works. Scale models are

often used in structural engineering, fluid dynamics, and have occasionally been used in fire

science. Model trains are familiar to all. A scale model in scientific work is simply a reduced-size

object on which certain measurements will be made. The mathematical model is a series of

equations which describe a certain process. If the equations are simple enough, they can be

solved on the hand calculator. More commonly, the equations are not so simple. Consequently,

a computer is required for their solution. Thus, in the fire field, we would speak of computer fire

model. 

molded-case circuit breaker—a circuit breaker that is assembled as an integral unit in a supporting

and enclosing housing of molded insulating material. (IEEE Std. 100-1988)

modulus of elasticity—as with yield strength, the modulus of elasticity degrades with temperature,

causing deformations at elevated temperatures. This degradation has serious impact on the

buckling behavior of columns and the midspan deflection of beams.

moisture content—moisture content will affect the thermal transmission qualities of an element

significantly, and in rigorous analysis becomes a very complex problem. Methods for idealizing the

treatment of moisture have been developed successfully. Water evaporation can also cause

chemical changes in material, usually resulting in discontinuous values of thermal properties.

Concrete and gypsum materials are good examples. Moisture content also affects the shrinkage

and modulus elasticity properties of concrete. Moisture condensation on reinforced and

prestressed cables also affects the temperature in these elements. 

multi-conductor cable (multiple conductor cable)—a combination of two or more conductors cabled

together and insulated from one another and from sheath or armor where used.

Note: Specific cables are referred to as 3-conductor cable, 7-conductor cable, 50-conductor cable,

etc. (IEEE Std. 100-1988).

National Fire Protection Association (NFPA) codes and standards—consensus codes and

standards intended to minimize the possibility and adverse consequences of fires.

negative phase —that portion of a blast wave whose pressure is below ambient.

neutral plane—the height in a compartment above which smoke will or can flow out during a fire

event. A neutral plane may change from one-half to one-third of the compartment height as the fire

becomes fully involved in flames. However, the smoke interface can extend very close to the floor

of the compartment.

non-combustible material—(a) material that, in the form in which it is used and under conditions

anticipated, will not ignite, burn, support combustion, or release flammable vapors when subjected

to fire or heat or (b) material having a structural base of noncombustible material, with a surfacing

not over 1/8 inch thick that has a flame spread rating not higher than 50 when measured in

accordance with the ASTM E84, “Standard Test Method for Surface Burning Characteristics of

Building Materials.”
F-43

non-essential (conductor, cable, component or system)—structures, systems, and components

(Class 1E, Non-Class 1E, safety related or non-safety related) whose operation is not required to

support the performance of systems credited in the SSA for accomplishing post-fire safe shutdown

functions.

norcotic effect—the effect of producing drowsiness and ultimately unconsciousness. Chemical

substances in smoke, when inhaled, can enter the bloodstream and interfere with the oxygen

supply to the brain, causing narcosis and possible death.

nonflammable—not capable of being ignited.

normally closed or normally open—the component status during normal operating modes of the

plant. This terminology is usually applied to valve, circuit breaker, and relay operating positions.

open circuit—a failure condition that results when a circuit (either a cable or individual conductor

within a cable) loses electrical continuity. 

open circuit—a failure condition that results when a circuit (either a cable or individual conductor

within a cable) loses electrical continuity. (Regulatory Guide 1.189)

Clarification: A circuit fault condition where the electrical path has been interrupted or "opened" at

some point so that current will not flow. Open circuits may be caused by a loss of conductor

integrity due to heat or physical damage (break). 

optical density—a number quantifying the fraction of a beam of light that is unable to pass through

a given smoke cloud.

overpressure—any pressure above atmospheric caused by a blast.

overcurrent—any current in excess of the rated current of equipment or the rated ampacity of a

conductor. It may result from overload, short-circuit, or ground-fault. A current in excess of rating

may be accommodated certain equipment and conductors for a given set of conditions. Hence, the

rules for overcurrent protection are specific for particular situations (IEEE Std. 100-1988).

overcurrent protection—a form of protection that operates when current exceeds a predetermined

value. (IEEE Std. 100-1988)

overcurrent relay—a relay that operates when its input current exceeds a predetermined value.

(IEEE Std. 100-1988).

overload—loading in excess of normal rating of equipment (IEEE Std. 100-1988).

overload—generally used in reference to an overcurrent that is not of sufficient magnitude to be

termed a short circuit. (IEEE Std. 100-1988). 

oxidization—removal electrons from an atom or molecule, usually by chemical reaction with oxygen.

oxidizing agent—chemical substance that gives up oxygen easily, removes hydrogen from another

substance, or attracts electrons.
F-44

oxygen starvation—for the case where there are no openings in the enclosure or only small

leakages areas, the hot gas layer will soon descend toward the flame region and eventually cover

the flame. The air entrained into the combustion zone now contains little oxygen and fire may die

out due to oxygen starvation. 

paired cable—a cable in which all the conductors are arranged in the form of twisted pairs 

(IEEE Std. 100-1988).

passive fire barriers—a fire barrier that provides its protective function while in its normal

orientation, without any need to be repositioned. (Examples of passive fire barriers include walls

and normally closed fire doors).

passive fire protection (PFP)—protection measures that prolong the fire resistance of an installation

before an eventual fire occurrence from the effects of smoke, flames, and combustion gases. These

can consist of insulation (fireproofing) of a structure, choice of noncombustible materials of

construction, use of fire-resistant partitions, and compartmentation to resist the passage of fire. It

includes coatings, claddings, or free-standing systems that provide thermal protection in the event

of fire and that require no manual, mechanical, or other means of initiation, replenishment, or

sustainment for their performance during a fire incident. Passive systems also embrace the basic

requirements for area separation and classification. (Nolan, 2000)

passive smoke detection system—a fire detection system where smoke is transported to and into

a sensing chamber by outside forces, that is, fire plume strength or environmental air-flows. A

passive smoke detection system may have difficulty detecting smoke from smoldering types of fires

because this smoke may not be hot enough to rise to the smoke detector location. (Nolan, 2000)

penetration seal—a purposely made seal (or seals) formed in situ to ensure that penetrations or

“poke through” to fire barriers do not impair its fire resistance. Wiring, cable or piping openings,

ducting through floors, ceilings, walls, and building joints must be provided with fire-rated

penetration seals to prevent the spread of fire or its effects. The penetration sealing material is to

be made of limited-combustible or noncombustible material that meets the requirements of ASTM

E 814, “Fire Tests of Through-Penetration Fire Stops,” or UL 1479, “Standard for Safety Fire Tests

of Through-Penetration Firestops”. (Nolan, 2000)

performance-based fire protection design—an engineering approach to fire protection design based

on (1) agreed upon fire safety goals, loss objectives, and design objectives; (2) deterministic and

probabilistic evaluation of fire initiation, growth, and development; (3) the physical and chemical

properties of fire and growth effluents; and (4) a quantitative assessment of the effectiveness of

design alternatives against objectives. One primary difference between a prescriptive and a

performance based design is that a fire safety goal life safety, property protection, mission

continuity, and environmental impact is explicitly stated. Prescriptive requirements may inhibit fire

safety components from effectively meeting the fire safety goals as an integrated system.

(Nolan, 2000)

performance codes—regulations providing for engineering analysis.

performance-based requirements—codes and standards that require design solution be engineered

to address the expected hazard in such a fashion that an acceptable level of safety (performance)

is ensured.
F-45

photoelectric (light scattering) smoke detector—a method of smoke detection that uses the

scattering of a light beam from the presence of smoke particles onto a photosensitive detector to

sense a fire condition and send a signal for alarm. (Nolan, 2000)

piloted ignition—ignition of flammable fuel-air mixture by a hot spot spark, or small flame (pilot).

(Quintiere, 1998)

pilot head detection system—a fire detection system that uses fusible heads on a pneumatic

charged system placed over the area of protection or hazard. Activation of the fusible head releases

the system pressure, which normally is linked by a pressure switch to a water suppression trip valve

to activate water flow to a deluge water spray system. The system provides forautomatic fire

detection and activation of protective devices or alarms. (Nolan, 2000)

plume—the column of hot gases, flames, and smoke rising above a fire. In a confined area a fire

plume rises almost vertically. In an outside, unconfined area the configuration of a fire plume is

affected by ambient conditions (wind, temperature, etc.). A fire plume consists of a flame plume,

a thermal column of combustion gases, and smoke particles. A fire plume’s temperature decreases

rapidly after the combustion process due to the entrainment of air. Therefore, the ignition hazard

from a fire plume is primarily dependent on the flame height of the plume. Objects located above

a flame are not likely to ignite unless large amounts of radiated heat are present or flame contact

is made. It may also be called a convection column, thermal updraft, or thermal column.

(Nolan, 2000)

pneumatic fire detection system—a fire detection system that detects fire from heat, which either

melts fusible elements (spot-type detection) in the system or a low melting point pneumatic (plastic)

tubing (linear detection). Loss of pressure in the system activates a pressure switch that sends a

signal for an alarm and fixed fire suppression system activation. (Nolan, 2000)

pool fire—a turbulent diffusion fire burning above an upward facing horizontal of vaporizing liquid

fuel (usually symmetrical) under conditions where the fuel vapor or gas has zero or very low initial

momentum. (Nolan, 2000)

positive phase—that portion of blast wave whose pressure is above ambient.

premixed flame—a flame in which fuel and air are mixed first before combustion. (Quintiere, 1998)

pre-flashover fire—the growth stage of a fire, where the emphasis in the fire safety engineering

design is on the safety of humans. The design load is in this case characterized by a heat release

rate curve, where the growth phase of the fire is most important.

potential transformer—a special class of transformer used to step down high distribution system

level voltages (typically 480V and above) to a level that can be safely measured by standard

metering equipment. PT's have a voltage reduction ratio given on their nameplate. A PT with a

voltage reduction ratio of 200: 5 would reduce the voltage by a ratio of 200 divided by 5 or 40 times.

post-flashover fire—when the objective of fire safety engineering design is to ensure structure

stability and safety of firefighters, the post-flashover fire is of greatest concern. The design load

in this case is characterized by the temperature-time curve assumed for the full developed fire

stage.
F-46

positive-pressure breathing apparatus—self-contained breathing apparatus in which the pressure

in the breathing zone is positive in relation to the immediate environment during inhalation and

exhalation. 

positive pressure ventilation (PPV)—the application of positive air ventilation to an enclosed fire

event to influence the degree of ventilation, aid in firefighting activities, and influence burning

activity. Mechanical ventilators (fans) are used to blow fresh air into an enclosure in sufficient

amounts to create a pressure differential within the enclosure that forces the existing air or products

of combustion through an exit opening in the enclosure. Positive pressure ventilation has been used

to assist in firefighting operations. (Nolan, 2000)

power cable/circuit—a circuit used to carry electricity that operates a load.

pre-discharge employee alarm—an alarm which will sound at a set time prior to actual discharge

of an extinguishing system so that employees may evacuate the discharge area prior to system

discharge.

pre-fire position/operating mode—terminology used to indicate equipment status prior to a fire. 

prescriptive requirements—detailed and often rigid measures mandated in codes and standards

as the means to ensure fire safety.

probable maximum loss (PML)—the loss due to a single fire scenario, which assumes an

impairment to one suppression system and a possible delay in manual fire-fighting response.

probabilistic safety assessment (PSA)—a comprehensive evaluation of the risk of a facility or

process; also referred to a probabilistic risk assessment (PRA).

product safety engineer—develops and conducts tests to evaluate product safety levels and

recommends measures to reduce or eliminate hazards. Establishes procedures for detection and

elimination of physical and chemical hazards and avoidance of potential toxic effects and other

product hazards. Investigates causes of accidents, injuries, and illnesses resulting from product

usage and develops solution. Evaluates potential health hazards or damage which could result

from misuse of products and applies engineering principles and product standards to improve

safety. May participate in preparation of product usage and precautionary label instructions.

(“Dictionary of Occupational Titles,” Volume 1, 14 Edition, U.S. Department of Labor Employment th

and Training Administration, 1991.)

protective relay—a device whose function is to detect defective lines or apparatus or other power

system conditions of an abnormal or dangerous nature and to initiate appropriate control action.

A protective relay may be classified according to its input quantities, operating principal, or

performance characteristics. (IPEEE Std. 100-1988)

Clarification: Protective relays are small, fast acting, automatic switches designed to protect an

electrical system from faults and overloads. A single 4160V switchgear have many relays, each

with a specific purpose. Protective relays are classified by the variable they monitor or the function

they perform. When a relay senses a problem (e.g., short circuit) it quickly sends a signal to one

or many circuit breakers to open, or trip, thus protecting the remainder of distribution system.

pyrolysis—the process of heating fuel to cause decomposition.
F-47

pyrophoricity—spontaneous combustion of a material upon exposure to air (atmospheric oxygen).

qualitative—measuring or describing with regards to characteristics, generalities, or trends.

quantitative—measuring or describing based on number or quantity.

qualitative risk analysis—an evaluation of risk based on the observed hazards and protective

systems that are in place, as opposed to an evaluation that uses specific numerical techniques

quantitative risk analysis—an evaluation of both the frequency and the consequences of potential

hazardous events to make a logical decision on whether the installation of a particular safety

measure can be justified on grounds of safety and loss control. Frequency and consequences are

usually combined to produce a measure risk that can be expressed as the average loss per year

in terms of injury or damage arising from an accidental event. The risk calculations of different

alternatives can be compared to determine the safest and most economical options. Calculated

risk may be compared to set criteria that have been accepted by society or required by law.

qualified cable—a cable that is certified to meet all of the requirements of the IEEE-383 standard

(including both the flame spread and the LOCA exposure test protocols).

quick disconnect valve—a device which starts the flow of air by inserting of the hose (which

leads from the facepiece) into the regulator of self-contained breathing apparatus, and stops the

flow of air by disconnection of the hose from the regulator. 

raceway—an enclosure channel of metal or nonmetallic materials designed expressly for holding

wires, cables, or busbars, with additional functions as permitted by code. Raceways include, but

are not limited to, rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquidtight flexible conduit, flexible metallic tubing, flexible metal conduit, electrical nonmetallic tubing,

electrical metallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor

raceways, surface raceways, wireways, and busways. 

(Regulatory Guide 1.189; IEEE Std. 100-1988).

raceway fire barrier—non-load-bearing partition type envelope system installed around electrical

components and cabling that are rated by test laboratories in hours of fire resistance and are used

to maintain safe shutdown functions free of fire damage. (Regulatory Guide 1.189)

radiation—heat transfer due to electromagnetic energy transfer such as light. (Quintiere, 1998)

Rankine (°R)—absolute Fahrenheit temperature scale, 460 °F. (Quintiere, 1998)

radiant energy (heat) shield—a non-combustible or fire resistive barrier installed to provide

separation protection of redundant cables, equipment, and associated non-safety circuits within

containment. (Regulatory Guide 1.189)

rated fire barrier—a fire barrier with a fire endurance rating established in accordance with the test

procedure of NFPA 251, “Standard Methods of Fire Test of Building Construction and Materials”.

rated voltage—the voltage at which operating and performance characteristics of apparatus and

equipment are referred. (IEEE Std. 100-1988).
F-48

rated voltage—for cables, either single-conductor or multiple conductor, the rated voltage is

expressed in terms of phase-to-phase voltage of a three phase system. For single phase systems,

a rated voltage of /3 * the voltage to ground should be assumed. (IEEE Std. 100-1988).

redundant shutdown—if the system is being used to provide its design function, it generally is

considered redundant. If the system is being used in lieu of the preferred system because the

redundant components of the preferred system do not meet the separation criteria of Section

III.G.2, the system is considered an alternative shutdown capability. 

redundant shutdown—for the purpose of analysis to Section III.G.2 criteria, the safe shutdown

capability is defined as one of the two normal safe shutdown trains. If the criteria of Section III.G.2

are not met, an alternative shutdown capability is required. (Generic Letter 86-10)

Note: For BWRs, the use of safety relief valves and low pressure injection systems has been found

to meet the requirements of a redundant means of post-fire safe shutdown under Section III.G.2

of 10 CFR 50, Appendix R.

regression rate—the burning rate of a solid or liquid, usually measured in centimeters per second

measured perpendicular to the surface.

relay—an electrically controlled, usually two-state, device that opens and closes electrical contacts

to effect the operation of other devices in the same or another electric circuit. 

(IEEE Std. 100-1988)

re-radiation—the radiation re-emitted from a heated surface. 

reflected pressure—impulse or pressure experienced by an object facing a blast.

remote shutdown—the capability, including necessary instrumentation and control, to safely

shutdown the reactor and maintain shutdown conditions from outside the main control room.

(Regulatory Guide 1.189)

remote control—control of an operation from a distance: this involves a link, usually electrical,

between the control device and the apparatus to be operated. (IEEE Std. 100-1988)

Note: Remote control may be accomplished from the control room or local control stations.

remote shutdown location—a plant location external to the main control room that is used to

manipulate or monitor plant equipment during the safe shutdown process. Examples include the

remote shutdown panel or valves requiring manual operation.

repair—to restore by replacing a part or putting together what is broken. 

(Webster’s Ninth New Collegiate Dictionary).

Response Time Index (RTI)—a relative measure of the sensitivity of an automatic fire sprinkler’s

thermal element as installed in a specific sprinkler. It is usually determined by plunging a sprinkler

into a heated laminar airflow within a test oven. This type of “plunge” test is not currently applicable

to certain sprinklers. These sprinklers must have their thermal sensitivity determined by other

standardized test methods. A response time index is also used to quantify the responses of heat

detectors used in a fire detection system. A normal RTI for a sprinkler is 300. Early suppression

fast response (ESFR) sprinklers have an RTI of 50 or less. (Nolan, 2000)
F-49

restricted area—any area to which access is controlled by the licensee for purposes of protecting

individuals from exposure to radiation and radioactive materials.

rich mixture—a mixture of flammable gas or vapor and air in which the fuel concentration is above

the fuel’s upper limit of flammability.

risk—risk is a quantitative measure of fire or explosion incident loss potential in terms of both the

event likelihood and aggregate consequences.

risk-informed—the risk-informed approach the analyst factors is not just the severity of a fire but

also the likelihood that the fire will occur. 

For example, based on the knowledge and experience of the equipment operator, a fire in a given

turbine generator is likely to occur 80-percent of the time. Or, based on the knowledge and

experience of the fire protection engineer, the sprinkler system protecting that generator is 90-

percent likely to be contain and control that fire. Because the risk-informed, performance-based

methodology quantifies the likelihood of a fire hazard and the likelihood that the fire protection

system will contain or control the fire it provides a more realistic prediction of the actual risk.

risk reduction—risk reduction in define as the application of technological or administrative

measures to reduce fire and explosion risk to a tolerable level.

safety engineer—develops and implements safety program to prevent or correct unsafe

environmental working conditions, utilizing knowledge of industrial processes, mechanics,

chemistry, psychology, and industrial health and safety laws. Examines plans and specifications

for new machinery or equipment to determine if all safety precautions have been included.

Determines amount of weight that can be safely placed on plant floor. Tour to inspect fire and

safety equipment, machinery, and facilities to identify and correct potential hazards and enclothing

and devices, and designs, builds, and installs, or directs installation or safety devices on machinery.

Conducts or coordinates safety and first aid training to educate workers about safety policies, laws,

and practices. Investigates industrial accidents to minimizes recurrence and prepares accident

reports. May conduct air quality tests for presence of harmful gases and vapors. (“Dictionary of

Occupational Titles,” Volume 1, 14 Edition, U.S. Department of Labor Employment and Training th

Administration, 1991.)

safety factor—safety factors have been used in most engineering designs to account for

uncertainties in calculations. Safety factors are also used in fire protection engineering designs,

especially for evacuation times and structural fire safety performance design. The addition of safety

factors to performance criteria permits the designer to make a conservative assessment while

allowing for smaller margin of error by accounting for uncertainty in the models, the input data and

the assumptions.

safe shutdown—for fire events, those plant conditions specified in the plant Technical Specifications

as Hot Standby , Hot Shutdown, or Cold Shutdown. (Regulatory Guide 1.189)

safe shutdown analysis (post-fire safe shutdown analysis)—a documented evaluation of the

potential effects of a postulated fire (including an exposure fire) and fire suppression activities in

any single area of the plant (fire area), on the ability to achieve and maintain safe shutdown

conditions in a manner that is consistent with established performance goals and safety objectives.

(i.e., Sections III.G and III.L of Appendix R or Position C.5.b of SRP 9.5.1).
F-50

safe shutdown system—all structures, equipment (components, cables, raceways cable enclosures

etc.), and supporting systems (HVAC, electrical distribution, station and instrument air, cooling

water, etc.) needed to perform a shutdown function.

self-heating—the result of exothermic reaction, occurring spontaneously in some materials under

certain conditions, whereby heat is liberated at a rate sufficient to rise the temperature of the

material.

seismic gap penetration seal—material to fill joints between fire resistance rated walls, floors, or

floor/ceiling assemblies which maintains continuity of the assembly. The seal system is often

multifunctional having fire, flood, and pressure ratings. 

severity—severity is a qualitative estimate of the hazard intensity in terms of source intensity, time,

and distance; for example heat flux, temperature, toxic or corrosive smoke concentration, explosion

over-pressure versus distance.

short circuit—a failure condition that results when a circuit (either a cable or individual conductor

within a cable) comes into electrical contact with another circuit. (Regulatory Guide 1.189)

short circuit—an abnormal connection (including an arc) of relatively low impedance, whether made

accidentally or intentionally, between two points of different potential. (IEEE Std. 100-1988)

short-to-ground—a short circuit between conductor(s) and a grounded reference point (e.g.,

grounded conductor, conduit, raceway, metal enclosure, shield wrap or drain wire within a cable).

short-to-ground—a failure condition that results when a circuit (either a cable or individual conductor

within a cable) comes into electrical contact with a grounded conducting device such as a cable

tray, conduit, grounded equipment, or grounded component. (Regulatory Guide 1.189)

solid conductor self-ignited cable fire—a conductor consisting of a single wire. (IPEEE Std.100-

1988). Electrical cables are often considered as a source of fire because they carry electric power

(a potential source of ignition) and are constructed of materials that can sustain combustion. A fire

that initiates from a cable, either due to a fault in the cable or due to a current overload, is refereed

to as a self-ignited cable fire.

SI units—an internationally accepted systems of measurement units.

small hose system—a system of hose ranging in diameter from 5/8" up to 11⁄2" which is for the use

of employees and which provides a means for the control and extinguishment of incipient stage

fires. 

smoke (from fire)—the mixture of tiny particles and gases produced by a fire. The particles consist

mainly of soot, aerosol mist, or boot, or gases, no longer chemically reacting, that emanate from

the fire.

smoke barrier—a continuous surface (wall, floor, HVAC damper, or ceiling assembly) that is

designed and constructed to restrict the movement of smoke. A smoke barrier may or may not also

have a fire resistance rating. Such barriers might have protected openings. (Nolan, 2000)
F-51

smoke bomb—a device for generating smoke from a chemical source (a pyrotechnic device) to

simulate fire conditions. Smoke bombs are used in confined spaces for testing and training

purposes (testing smoke detection, smoke management systems, or firefighter training). They

usually produce smoke at a standard rate and quality and can be supplied in various durations.

Smoke bombs are sometimes called smoke candles. (Nolan, 2000)

smoke chaser—terminology used for a forest firefighter who is lightly equipped to enable him or her

to get to a fire quickly. (Nolan, 2000)

smoke compartment—an area enclosed by smoke barriers on all sides, including the top and

bottom. (Nolan, 2000)

smoke condensate—the condensed residue of suspended vapors and liquid products of incomplete

combustion. (Nolan, 2000)

smoke control—the control of smoke movement by the use of the airflow by itself, if it is of sufficient

velocity and application of air pressure differences of sufficient strength across a barrier. Dilution

of a smoke environment by only supplying air and extracting air is not considered a method of

smoke control within an enclosure for fire safety concerns. (Nolan, 2000)

smoke control system—a system to limit and direct smoke movement within a building to protect

occupants and assist with evacuation measures. It consists of mechanical fans that are engineered

to produce air flows and pressure differences within the building compartments to achieve smoke

control. (Nolan, 2000)

smoke control zone—the subdivision of a building to inhibit the movement of smoke from one area

to another for the purpose of life safety, evacuation, and property protection. A smoke control zone

can consist of one or more floors, or a floor can consist of more than one smoke control zone.

Each zone is separated from the others by partitions, floors, and doors that can be closed to

prevent the spread of smoke. (Nolan, 2000)

smoke curtain—salvage covers placed around an area by the fire service to prevent the spread of

smoke that may cause further damage. (Nolan, 2000)

smoke damage—the harmful effects to property from the occurrence of unwanted smoke exposure

and combustion gases, consisting of stains, odors, and contamination. Exposure of combustion

gases and smoke in some locations may cause property damages higher than physical fire

damages. High technology clean rooms and the food processing industry, for example, require high

cleanliness standards for their products and smoke damage may cause harmful chemicals to

deposited on the products, making them unsuitable for use or salvage. (Nolan, 2000)

smoke damper—a device to restrict the passage of smoke through a duct that operates

automatically and is controlled by a smoke detector. (Nolan, 2000)

smoke density—the relative quantity of solid and gaseous airborne products of combustion in a

given volume. (Nolan, 2000)

smoke detection—the sensing of the products of combustion and sending a signal or an alarm for

the purpose of safeguarding life or property. Various devices are available that can sense the

presence of smoke, which is considered evidence of unwanted combustion. (Nolan, 2000)
F-52

smoke detector—a device that senses visible or invisible particles of combustion. They are very

effective for a slow smoldering fire and will generally provide an alarm before a heat detector. They

may cause a false alarm or be ineffective if not sited and installed where air currents from

ventilation or air conditioning systems are likely to carry smoke and other products of combustion

away from the detectors. Usually used to warn occupants of a building of the presence of a fire

before it reaches a rapidly spreading stage and inhibits escape or attempts to extinguish it. On

sensing smoke, the detectors emit a loud, high-pitched alarm tone, usually warbling or intermittent,

and are usually accompanied by a flashing light. There are two types of smoke detector:

photoelectric and ionization. Photoelectric smoke detectors utilize a light-sensitive cell in either of

two ways. In one type, a light source (a small spotlight) causes a photoelectric cell to generate

current that keeps an alarm circuit open until visible particles of smoke interrupt the ray of light or

laser beam, breaking the circuit and setting off the alarm. The other photoelectric detector widely

used in private dwellings employs a detection chamber shaped so that the light-sensitive element

cannot ordinarily “see” the light source (usually a light-emitting diode, LED). When particles of

smoke enter a portion of the chamber that is aligned with both the LED and the photocell, the

particles diffuse or scatter the light ray so it can be “seen” by the photocell. Consequently, a current

is generated by the light-sensitive cell, producing an alarm.

• Ionization detectors employ radioactive material in quantities so tiny they are believed to

pose no significant health hazard to ionize the air molecules between a pair of electrodes

in the detection chamber. This enables a minute current to be conducted by the ionized air.

When smoke enters the chamber, particles attach them-selves to ions and diminish the flow

of current by attaching themselves to the ions in the air from the radioactive source. The

reduction in current sets off the alarm circuit.

• Photoelectric smoke detectors are relatively slow to respond and are most effective in

sensing the larger smoke particles generated by a smoldering, slow-burning fire. Ionization

detectors are much faster to respond and are best at sensing the tiny smoke particles

released by a fast-burning fire. Ionization smoke detection is also more responsive to

invisible particles (smaller than 1 micron in size) produced by most flaming fires. It is

somewhat less responsive to the larger particles typical of most smoldering fires. For this

reason, some manufacturers produce combination versions of detectors. Many fire

prevention authorities recommend the use of both photoelectric and ionization types in

various locations in a private home. Either type of detector can be powered by batteries or

by household current. Air sampling smoke detectors is a fire detection system where smoke

is transported to and into a sampling port but they aspirate smoke into the detector sensing

chamber rather than chamber using suction fans. Smoke in the immediate vicinity of the

sampling ports is drawn into the detector sensing chamber. Air sampling smoke detectors

have been employed in zero gravity environments (space vehicles) to detect the presence

of smoke. The first smoke alarm was invented by W. Jaeger and E. Meili of Switzerland in

1941. The alarm was part of a project named Minerva Fire Alarm System. It was battery

powered and had a flashing light and audible alarm when activated. It was also capable of

sending a signal to the local fire station. (Nolan, 2000)
F-53

smoke detector, duct—a device located within a building air-handling duct, protruding into the duct,

or located outside the duct that detects visible or invisible particles of combustion flowing within the

duct. Actuation of the device may allow operation of certain control functions. National and local fire

codes recognize the hazard posed by building air-handling systems to spread smoke, toxic gases,

and flame from one area to another unless they are shut down. The primary purpose of duct smoke

detection is to prevent injury, panic, and property damage by preventing the spread (re-circulation)

of smoke. Duct smoke detection can also assist in protecting the air-handling system itself as well

as sensitive equipment such as computer hardware. Duct smoke detectors may also be used to

activate smoke exhaust dampers. Duct smoke detectors are not rated to be used as general area

protection nor are general area detectors listed as duct smoke detectors. It may also be called a

duct detector (DD). (Nolan, 2000)

smoke developed index (SDI)—a relative index of smoke produced during the burning of a material

as measured by a recognized test. The smoke developed rating of materials is deter-mined by

NFPA 255, “Standard Test of Surface Burning Characteristics of Building Materials”; ASTM E84,

“Surface Burning Characteristics of Building Materials”; and UL 723, “Tests for Surface Burning

Characteristics of Building Materials.” (Nolan, 2000)

smoke developed rating—a relative index for the smoke produced from a building material test

sample as measured and calculated by the Steiner Tunnel Tests (NFPA 255, “Standard Method

of Test of Surface Burning Characteristics of Building Materials”; ASTM E84, “Surface Burning

Characteristics of Building Materials”; or UL 723, “Tests for Surface Burning Characteristics of

Building Materials”). Red oak has a rating of 100, whereas cement board has a rating of zero. It

may also be called a smoke density index (SDI). (Nolan, 2000)

smoke eater—slang terminology referring to a firefighter. It has been applied due to the consequences of firefighters inhaling smoke during a fire incident. (Nolan, 2000)

smoke ejector—a device similar to a fan used to exhaust heat, smoke, and harmful combustion

gases from a post-fire enclosed environment and to induct fresh air to the affected enclosure.

Smoke ejectors are usually carried as part of the complement of equipment on a fire-fighting vehicle

and are commonly electrically powered. (Nolan, 2000)

smoke exhaust system—natural (chimney) or mechanical (fans) ventilation for the removal of

smoke from an enclosure to its exterior. The provision of a tenable environment for human life is

not considered within the capability of a smoke exhaust system. (Nolan, 2000)

smoke extraction—the removal of smoke from an enclosed structure to aid firefighting operations.

It is generally acknowledged that correct ventilation in fire conditions reduces (lateral) fire spread

and resultant damage, enables firefighters to enter a building fire more easily, and provides greater

visibility for fire-fighting activities. Manual efforts at the time of the fire may be employed, either

through rapidly cut openings or the use of portable smoke extraction fans. Where smoke production

may be anticipated in buildings, they are provided with automatic smoke extraction devices.

(Nolan, 2000)

smoke extractor—machine or fan blower device for extracting or removing smoke and gases from

a building or an enclosure. 
F-54

smokehouse—a structure used to provide simulated smoke conditions for the training of firefighters.

Training is provided in smoke environments where conditions can be monitored and observations

made to improve performance. Simulated smoke is used as a safety measure and real fires are

avoided. (Nolan, 2000)

smoke gas explosion—when unburnt gases from an unventilated fire flow through leakages into an

closed space connected to the fire room, the gases there can mix very well with air to form a

combustible gas mixture. A small spark is then enough to cause a smoke gas explosion, which can

have very serious consequences. This phenomenon is, however, very observed in enclosure fires.

smoke inhalation—the breathing of the combustion products into the lungs. It is considered an

injury that damages the respiratory system. The main dangers of smoke inhalation to the lungs are

the presence of narcotic gases, principally carbon monoxide (CO), hydrogen cyanide (HCN), carbon

diox 2ide (CO ), and the asphyxiating effects of an oxygen-depleted atmosphere. Inhalation of

narcotic gases often leads to hyperventilation, leading to an increase in the amount of narcotic

gases taken into the lungs.

Narcotic gases also cause incapacitation by attacking the central nervous system. A low level of

oxygen in the blood results in low oxygen levels to the brain, which causes impaired judgment and

concentration. These effects may confuse, panic, or incapacitate an individual. Incapacity occurs

in less than 10 minutes with a 0.2 percentage concentration of carbon monoxide (CO) if heavy

activities are being performed. Carbon monoxide combines with the hemoglobin of the blood,

preventing oxygen from binding with hemoglobin, which will cause death. Carbon monoxide has

an affinity to hemoglobin 300 times that of oxygen. The degree of poisoning depends on the time

of exposure and concentration of the combustion gases. If the percentage of carbon monoxide in

the blood rises to 70 to 80-percent, death is likely to ensue. Hydrogen cyanide is also referred to

as hydrocyanic acid. The cyanides are true proto-plasmic poisons, combining in the tissues with

enzymes associated with cellular oxidation. They therefore render oxygen unavailable to the

tissues and cause death through asphyxia. Inhaling concentrations of more than 180 ppm of HCN

leads to unconsciousness in a matter of minutes, but the fatal effects would normally be caused by

carbon monoxide poisoning after HCN has made the victim unconscious. Exposure to

concentrations of 100 to 200 ppm for periods of 30 to 60 minutes can also cause death. Inhalation

of hot smoke gases into the lungs will also cause tissue damage (burns) such that fatal effects

could result in 6 to 24 hours after the exposure. Whenever the effects of smoke may affect

individuals, protective measures must be provided, such as smoke management systems, smoke

barriers, or fresh air supplies. (Nolan, 2000)

smoke interface—the layer in a compartment that separates the smoke layer from the non-smoke

layer. A smoke layer will gradually increase as the fire increases if the smoke layer is not vented,

which lowers the smoke interface and may eventually fill the compartment. Fully developed fires

have a smoke interface several centimeters (inches) above the floor. Cooling, or a decrease in the

fire, may allow the smoke layer to dissipate and the interface will rise. May also be called smoke

layer interface. (Nolan, 2000)

smoke layer—the accumulated thickness of smoke in an enclosure. (Nolan, 2000)
F-55

smoke management system (SMS)—natural or mechanical ventilation for the control or removal

of smoke from an enclosure. Smoke management systems provide for smoke control to assist in

personnel evacuation and firefighting activities. They provide pressurized areas within a building

to prevent the entrance of smoke or to direct smoke to the outside of the building. Smoke control

systems can be designated a dedicated or nondedicated. A dedicated smoke control system is

provided for smoke control only within an enclosure. It is a separate air moving and distribution

system that does not function under normal building operating conditions. It is specifically

designated for smoke control functions. A nondedicated smoke control system shares its

components with other building systems such as the heating, ventilation, and air conditioning

(HVAC) system. Activation of it causes the system to change its mode of operation from normal

building HVAC requirements to that of smoke control. (Nolan, 2000)

smoke pencil—a chemical solid that is ignited to produce smoke for testing purposes, primarily for

the integrity testing of enclosures that are protected by fixed gaseous fire suppression systems.

(Nolan, 2000)

smoke-proof—resistant to the spread of smoke. (Nolan, 2000)

smoke shaft—a continuous shaft extending the full height of a building, with opening at each floor

and a fan at the top; during a fire, the dampers on the fire floor open and the fan vents the

combustion products.

smoke seal—a flexible membrane provided around the edge of a rated fire door frame. It is used

to prevent the passage of smoke particles and combustion gases through the door seam

surrounding a fire-rated door when it is closed.

smoke stop—a barrier provided to stop the spread of smoke to another area. (Nolan, 2000)

smoke test—a method for confirming the integrity of a chimney and for detecting any cracks in a

masonry chimney flue, or deterioration or breaks in the seal or joints of a factory-built or metal

chimney flue. Smoke is generated in a fire-place or solid fuel-burning appliance while

simultaneously covering the chimney termination. Smoke leakages are then checked for through

the chimney walls or suspected openings. (Nolan, 2000)

smoke visibility—the ability to perceive objects through smoke at a specific distance. Smoke

visibility is necessary during fire conditions for evacuation of occupants, rescue operations, and

firefighting activities. The ability to see through smoke is a measure of smoke visibility and can be

related to the mass optical density (the yield of solid and liquid particulates of smoke generation).

Smoke reduces visibility by a reduction in available light through the absorption and scattering of

light by the smoke particulates. (Nolan, 2000) 

smoldering—a slow combustion process between oxygen and a solid fuel. (Quintiere, 1998)

soot—tiny particles consisting of carbon, often formed in diffusion flames and in very rich premixed

flames. 
F-56

spalling—generally, the breaking away or explosion of concrete materials from a fire exposure. It

occurs due to stresses set up by steep temperature gradient onto aggregates in the concrete that

expand, or moisture that is trapped and vaporizes without any means of venting safely. Major

factors that affect spalling behavior are moisture contact, rate of temperature rise, permeability,

porosity, restraint, and reinforcement. Spalling also is known to occur in fire-resistant protective

coating for steel where asbestos or other fiber fillers are added to concrete or other cementitious

material to increase insulation value. Spalling promotes exposure of structural steel, steel

reinforcing or pre-stressing cables; thermal transmission due to decreased section thickness; fire

passage due to openings caused by extreme spalling; and degradation in moment-bearing capacity

due to reduced element cross sections. (Nolan, 2000)

species—another name for chemical compounds, usually gases. (Quintiere, 1998)

specific heat—property that measures the ability of matter to store energy. (Quintiere, 1998)

spot detector—a device whose detection element is concentrated at a particular location.

Examples are bimetallic detectors, fusible alloy detectors, local rate-of-rise and smoke detectors,

and thermoelectric detectors. Spot-type detectors have a defined area of coverage. (Nolan, 2000)

spontaneous combustion—the outbreak of fire without application of heat from an external source.

Spontaneous combustion may occur when combustible matter, such as hay or coal, is stored in

bulk. It begins with a slow oxidation process (bacterial fermentation or atmospheric oxidation)

under conditions not permitting ready dissipating of heat, such as in the center of a haystack or a

pile of oil rags. Oxidation gradually raises the temperature inside the mass to the point at which

a fire starts.

spontaneous combustion—ignition of a combustible material caused by the accumulation of heat

from oxidation reactions.

spontaneous heating—slow oxidation of an element or compound which causes the bulk

temperature of the element/compound to rise without the addition of an external heat source.

spontaneous ignition—ignition that occurs as a result of progressive heating, as contrasted with

instantaneous ignition caused by exposure to a spark or a flame. The spontaneous ignition can

result from self-heating caused by slow oxidation, or from an external heat source. 

sprinkler—a water deflector spray nozzle device used to provide distribution of water in specific

characteristic patterns and densities for the purpose of cooling exposures exposed to unacceptable

heat radiation, and controlling and suppressing fires or combustible vapor dispersions. Water

droplet size from a discharging sprinkler is one key factor in deter-mining the effectiveness of its

water spray. Water droplets penetrate a fire plume to reach a burning commodity by two modes:

gravity and momentum. In the gravity mode, the downward velocity of the water droplets falling

through a fire plume must be greater than the upward velocity of the fire plume for it to reach the

base of the fire. Gravity action alone cannot accomplish this. Increased system pressure provides

water droplets with greater downward thrust (momentum) to over-come the upward thrust of the fire

plume. (Nolan, 2000)

sprinkler, automatic—a fire suppression or control device that operates automatically when its heatactuated element is heated to its thermal rating or above, allowing water to discharge over a

specific area. (NFC Online Glossary)
F-57

sprinkler density—calculated by gallons per minute discharge divided by the square footage

covered.

sprinkler, dry (pendent)—an automatic sprinkler that is not provided with water continuously at its

inlet. It is provided where freezing conditions are a concern if the sprinkler system is seasonally

drained down. A seal is provided at the main supply pipe to prevent water from entering the

sprinkler assembly until the sprinkler is activated from fire conditions. Typically, it is designed so

that the fusible element opens the sprinkler and releases a spring-loaded tube that breaks the glass

inlet water seal. This allows water to flow to the sprinkler. pattern of the sprinkler. (Nolan, 2000)

sprinkler, on-off—a cycling (on-off), self-actuating snap-action, heat-actuated sprinkler. Water flow

automatically shuts off from the sprinkler when the fire has been extinguished (no heat is available

to activate the sprinkler head) and it is automatically reset for later operations. This type of

sprinkler requires a water supply that is free of contaminants (potable) that could interfere with its

operation. It does not have to be replaced after operation. It is provided to avoid water damage by

eliminating the need to shut off the water supply after a fire has been extinguished. Typical

applications include areas containing high-value inventories, materials, or equipment highly

sensitive to water areas subject to flash or repeat fires, and where the water supply is limited.

(Nolan, 2000)

sprinkler, open—a sprinkler device that has a permanent open orifice and is not actuated by a heat

responsive element. Instead, an upstream device controls water flow from the sprinkler. Its primary

purpose is to provide adequate distribution of water in a prescribed pattern. (Nolan, 2000)

sprinkler, pendent—a sprinkler designed for and installed with the head in a downward fashion from

the piping, rather than placed in an upward position above the supply pipe. They are primarily used

where upright sprinklers cannot be used because of lack of space (headroom) or where

concealment of sprinkler piping above a false ceiling is desired because of aesthetic reasons (office

areas). (Nolan, 2000)

sprinkler, pilot—an automatic sprinkler head or thermostatic fixed temperature device used in a

pneumatic or hydraulic fire detection system, normally connected to an actuating valve that

releases when the pilot device is activated. (Nolan, 2000)

sprinkler pintle—an indicating device on sprinklers that have small and large orifices and a standard

0.5 in. (1.27 cm) pipe thread. A pintle highlights the sprinkler orifice size difference compared to

standard orifices; that is, 0.5 in. (1.27 cm) sprinklers with 0.5 in. (1.27 cm) pipe threads. It consists

of a small, short cylinder centrally mounted and perpendicular to the deflector plate, on the side

opposite the water discharge. (Nolan, 2000)

sprinkler, recessed—sprinklers in which all or part of the body, other than the shank thread, is

mounted within a recessed housing. Recessed sprinklers are mainly provided for aesthetic reasons,

although protection of the sprinkler installed, tested, and evaluated before the installation of the

finished ceiling. (Nolan, 2000)

sprinkler, residential—a type of fast-response sprinkler that is well known for its ability to enhance

human survivability in the room of fire origin and is used in the protection of dwelling units as

specified by listing or approval agencies. The first effective fast-response sprinkler for residential

use was developed by the Factory Mutual Research Corporation (under contract to the United

States Fire Administration) and was demonstrated in 1979. (Nolan, 2000)
F-58

sprinkler riser—the vertical portion of a sprinkler system piping from the ground main to the

horizontal cross main that feeds the branch lines. (Nolan, 2000)

sprinkler, sidewall—sprinkler designed to be installed on piping along the sides of a room instead

of the normal sprinkler spacing requirements. The sprinkler is made with a special deflector that

deflects most of the water away from the nearby walls in a pattern similar to a quarter of a sphere.

A small portion of the water is directed at the wall behind the sprinkler. Sidewall sprinklers are

generally used because of aesthetic concerns, building construction arrangements, or installation

economy considerations. (Nolan, 2000)

sprinkler spacing—distribution of automatic sprinklers to provide the area coverage specified for

light, ordinary, and extra hazardous occupancies. (Nolan, 2000)

sprinkler system—for fire protection purposes, an integrated system of underground and overhead

piping designed in accordance with fire protection engineering standards. The installation includes

one or more automatic water supplies. The portion of the sprinkler system above ground is a

network of specially sized or hydraulically designed piping installed in a building, structure, or area,

generally over-head, and to which sprinklers are attached in a systematic pattern. The valve

controlling each system riser is located in the system riser or its supply piping. Each sprinkler

system riser includes a device for actuating an alarm when the system is in operation. The system

is usually activated by heat from a fire and discharges water over the fire area. 

The first recorded patented sprinkler system was developed in London in 1806 by John Carey. It

consisted of a pipe fed by a gravity tank with a number of valves held closed by counterweights on

strings; when a fire burned the strings, the valves were opened. The sprinkler head consisted of

an outlet similar to a water can perforated nozzle that faced downward. A refined sprinkler system

was patented (British Patent No. 3201) by William Congreve in 1809. His system used fusible metal

on the wires controlling water supply valves and had various water distribution devices including

perforated pipes, devices similar to sidewall sprinklers. Many manually operated systems were

installed in 19 century buildings. The first system in America was installed in a plant in Lowell,

th

Massachusetts in about 1852. A number of perforated pipes were fed by a main riser that could be

turned on in an adjoining area. James B. Francis improved the distribution of this system by using

pipe with perforations about 0.1 in. (0.25 cm) in diameter and spaced 9 in. (22.86 cm) apart,

alternately on different sides, to provide a spray at water at an angle slightly above the horizontal.

Insurance companies of the time continued to improve on the design. These systems resulted in

frequent water damage in parts of a room or building untouched by fire. An improvement was

sought and found in the Parmelee sprinkler head, which was introduced in the United States in the

1870s. The Parmelee head had a normally closed orifice that was opened by heat from a fire. The

first sprinkler successfully used over a long period was the Grinnel “glass button,” which appeared

in 1890 (previous Grinnel types were developed from 1884 to 1888). Since about 1900, most

changes to sprinklers have been refinements in the design (deflector or activating mechanism

improvements) rather than conceptual changes. Modern versions use a fusible link or a bulb

containing chemicals that breaks at about 160 °F (70 °C) to open the orifice. Modern sprinkler

heads are designed to direct a spray downward. Most sprinkler systems are wet-head; that is, they

use pipes filled with water. Where there is danger of freezing, however, dry-head sprinklers are

used, in which the pipes are filled with air under moderate pressure; when the system is activated,

the air escapes, opening the water-feeder valves. An improved version has air under only

atmospheric pressure and is activated by heat-sensing devices. Another special type, used in highhazard locations, is the deluge system, which delivers a large volume of water quickly. The

definitions of several types of sprinkler systems follow. (Nolan, 2000)
F-59

• wet pipe system—a sprinkler system that uses automatic sprinklers installed in a piping

system containing water and connected to a water supply. Individual sprinklers discharge

immediately when they are affected by the heat of a fire. Sprinklers that are not affected by

the heat remain closed. It is used where there is no danger of the pipes freezing and where

no other conditions require the use of a special system. A wet pipe sprinkler system that

uses automatic sprinklers installed in a piping system containing an antifreeze solution and

connected to a water supply. The antifreeze solution is discharged (followed by water)

immediately upon operation of the sprinklers, which are opened from the heat effects from

a fire.

• dry pipe system—a sprinkler system that uses automatic sprinklers installed in a piping

system containing air or nitrogen under pressure. A release of pressure on the system (as

from the opening of a sprinkler) permits the water pressure to open a valve known as a dry

pipe valve. The water then flows into the piping system and out the opened sprinklers. Dry

pipe systems operate more slowly than do wet pipe systems and are more expensive to

install and maintain, therefore they are only used where there is an absolute necessity, such

as freezing conditions.

• pre-action system—a sprinkler system using automatic sprinklers installed in a piping

system containing air that may or may not be under pressure, with a supplemental detection

system installed in the same areas as the sprinklers. Actuation of a detection system opens

a valve that permits water to flow into the sprinkler piping system and to be discharged from

any sprinklers that have opened from the effects of a fire. Sprinklers that are not affected

by heat from a fire remain closed. They are designed to counteract the operational delay

of dry pipe systems and eliminate the damage from a broken pipe or sprinkler head.

• combined dry pipe and pre-action system—a sprinkler system that uses automatic

sprinklers installed in a piping system containing air under pressure, with a supplemental

fire detection system installed in the same areas as the sprinklers. Operation of the

detection system actuates tripping devices that open dry pipe valves simultaneously without

a loss of air pressure in the system. Operation of the fire detection system also opens air

exhaust valves at the end of the system feed main, facilitating the filling of the system with

water, which normally occurs before any sprinklers open. The detection system also serves

as an automatic fire alarm system for the area. Only sprinklers that are affected by heat

from a fire are opened; others remain closed.

• deluge system—a sprinkler system using open sprinklers installed in a piping system

connected to a water supply through a valve that is opened by the operation of a detection

system installed in the same areas as the sprinklers. When the deluge valve opens, water

flows into the system piping and discharges from all sprinklers. There are no closed

sprinklers in a deluge system. Its objective is to deliver the most amount of water in the least

amount of time. Deluge systems are specified for high hazard locations where a fire occurs

quickly and reaches very high temperatures, such as from highly flammable fuels.

• water spray system—a fixed pipe system connected to a water supply and equipped with

spray nozzles for specific discharge and distribution over the surface or area to be

protected. The piping system is connected to the water supply through an automatic or

manually activated valve that initiates the flow of water. The control valve is actuated by the

operation of automatic fire detection devices installed in the same area as the water spray

nozzles (in special cases the automatic detection devices may be located in another area).

• foam-water sprinkler system—a fire protection piping system that is connected to a source

of air-foam concentrate and a water supply and is equipped with appropriate discharge

devices for extinguishing agent discharge and for distribution over the area to be protected.
F-60

• foam-water spray system—a fire protection piping system connected to a source of air-foam

concentrate and a water supply and equipped with foam-water spray nozzles (aspirating or

non-aspirating) for extinguishing agent discharge and for distribution over the area to be

protected.

Fire protection sprinkler systems may also have several different piping arrangements:

• gridded system—a sprinkler system piping arrangement where parallel cross-mains are

connected by multiple branch lines. An operating sprinkler receives water from both ends

of its branch line while other branch lines help transfer water between cross-mains.

• looped system—a sprinkler system piping arrangement where multiple cross-mains are

connected to provide more than one path for water to flow to an operating sprinkler, and

branch lines are connected to each other.

• circulating closed-loop system—a wet pipe sprinkler system that has a non-fire-protection

connection to an automatic sprinkler system in a closed-loop piping arrangement. This

allows the sprinkler piping to conduct water for heating or cooling in an economical fashion

without impacting the ability of the sprinkler system to support its fire protection purpose.

Water is not removed or used from the system, but is only circulated through the piping

system.

sprinkler temperature classes—sprinklers are designated to operate at specific fire temperatures

and are segregated into temperature classes. The actual temperature rating of sprinklers may be

less important than is popularly perceived. Where ceiling temperatures rise rap-idly, the difference

between 165 °F (74 °C) and 212 °F (100 °C) for the first sprinkler to operate may not be important,

but it may affect the number of heads that operate. Higher temperature sprinklers are used where

the ambient temperatures may be higher than ordinary temperature ratings.

sprinkler tong—a portable tool used to stop the flow from a sprinkler head.

sprinkler types:

• spray sprinkler

• conventional sprinkler

• fast-response sprinkler

• residential sprinkler

• extended coverage sprinkler

• quick-response sprinkler

• quick-response extended coverage sprinkler

• large-drop sprinkler

• early suppression fast response sprinkler (ESFR)

• open sprinkler

• special sprinkler

• specific application sprinkler

• flush sprinkler

• concealed sprinkler

• recessed sprinkler

• corrosion-resistant sprinkler

• in-rack sprinkler

• dry sprinkler
F-61

sprinkler, upright—a sprinkler designed for and placed in an upward position above the sup-ply

pipe, rather than installed in a downward fashion from the supply pipe. It directs 100-percent of its

water toward the floor. A sprinkler designated for upright installation cannot be used in the

downward position because the water will be directed to the ceiling instead of toward the fire

incident and will not achieve its density pattern for fire control and extinguishment. (Nolan, 2000)

spurious actuation—an undesirable actuation of a component or system due to an uncontrolled or

unintended signal.

spurious actuation/operation—a change (full or partial) in the operating mode or position of

equipment. These operations include but are not limited to: (a) opening or closing normally closed

or open valves, (b) starting or stopping of pumps or motors, (c) actuation of logic circuits, (d)

inaccurate instrument reading.

spurious operation—the undesired operation of equipment resulting from a fire that could affect the

capability to achieve and maintain safe shutdown. (Regulatory Guide 1.189)

spurious indications—false indications (process monitoring, control, annunciator, alarm, etc.) that

may occur as a result of fire and fire suppression activities.

spurious signals—false control or instrument signals that may be initiated as a result of fire and fire

suppression activities.

suppression—the sum of all the work done to extinguish a fire from the time of its discovery.

stack effect—the air or smoke movement of migration through a tall building due to pressure

differentials caused by temperature.

stair pressurization—increasing the air pressure in stair wells (usually with fan systems) to provide

refuge area from fire and smoke.

standard—document that address a specific fire safety issue. There are standard practices for

installing and inspecting fire protection equipment; and standard methods for testing personal

protective equipment, building products and fire protection equipment.

standard sprinkler pendent (SSP)—a sprinkler designated to be installed with its outlet oriented to

allow its spray to be directed upward.

standard sprinkler upright (SSU)—a sprinkler designated to be installed with its outlet

orientated to allow the spray to be directed downwards. 

standpipe hose cabinet—a cabinet provided for the provision of standpipe outlets and/or fire hose

storage. Fire hoses are usually pre-connected and stored in a rack with release pins.

standpipe, manual—a standpipe system that relies on the fire service to supply water to it to meet

its demands.

standpipe, semi-automatic—a standpipe system that is connected to an adequate water supply, but

requires a control device activation to supply water to the hose outlets.
F-62

standpipe system—the provision of piping, riser pipes, valves, firewater hose connections, and

associated devices for the purpose of providing or supplying firewater hose applications in a

building or structure by the occupants or fire department personnel. Standpipe systems are

classified according to their intended use by the building occupants, the fire department, or both.

Many high-rise or other large buildings have an internal system of water mains (standpipes)

connected to fire hose stations. Trained occupants or employees of the building management

operate the hoses until the fire department arrives. Firefighters can also connect their hoses to

outlets near the fire. The National Fire Protection Association (NFPA) classifies standpipe systems

based on their intended use as Classes I, II, or III. Class I is provided for fire service use or other

personnel trained in handling heavy fire streams. It is distinguished by the provision of 2.5 in. (6.35

cm) hose stations or hose connections. A Class II standpipe system is provided for use by the

building occupants and by the fire service during initial attack operations. It is characterized by the

provision of 1.5 in. (3.81 cm) hose stations. A Class III standpipe system combines both the

features of Class I and Class II systems.

For fire protection purpose, an integrated system of underground and overhead piping designed

in accordance with fire protection engineering standards. The installation includes one or more

automatic water supplies. The portion of the sprinkler system aboveground is a network of specially

sized or hydraulically designed piping installed in a building, structure, or area, generally overhead,

and to which sprinklers are attached in a systematic pattern. The valve controlling each system

riser is located in the system riser or its supply piping. Each sprinkler system riser includes a

device for actuating an alarm when the system is in operation. The system is usually activated by

heat from a fire and discharged water over the fire area.

standpipe systems

Class I standpipe system—a 21⁄2" hose connection for use by fire departments and those trained

in handling heavy fire streams. 

Class II standpipe system—a 11⁄2" hose system which provides a means for the control or

extinguishment of incipient stage fires. 

Class III standpipe system—a combined system of hose which is for the use of employees trained

in the use of hose operations and which is capable of furnishing effective water discharge during

the more advanced stages of fire (beyond the incipient stage) in the interior of workplaces. Hose

outlets are available for both 11⁄2" and 21⁄2" hose. 

standpipe, wet—a standpipe system that is permanently charged with water for immediate use.

static ignition hazard—an electrical charge build-up of sufficient energy to be considered an ignition

source. For an electrostatic charge to be considered an ignition source, four conditions must be

present: (1) a means of generating an electrostatic charge, (2) a means of accumulating an

electrostatic charge of sufficient energy to be capable of producing an incendiary spark, (3) a spark

gap, and (4) an ignitable mixture in the spark gap. Removal of one or more of these features will

eliminate a static ignition hazard. Static charges can accumulate on personnel and metallic

equipment. If the static accumulation is separated by materials that are electrically nonconducting,

a dangerous potential difference may occur. These nonconducting materials or insulators act as

barriers to inhibit the free movement of electrostatic charges, pre-venting the equalization of

potential differences. A spark discharge can occur only when there is no other available path of

greater conductivity by which this equalization can be affected (bonding or grounding).

S
F-63

spurious operation—the undesired of equipment resulting from a fire that could affect the capability

to achieve and maintain safe shutdown.

standard time-temperature curve—curve representing the standard reproducible test fire used since

1918 to measure the fire endurance of building materials.

Stefan-Boltzmann law—an equation that specifies the intensity of radiation emitted by an object,

in terms of its absolute temperature (K).

steiner tunnel test—test to determine the surface burning characteristics of building materials in

which the flame spread of the test material is compared to asbestos cement board, rated 0, and red

oak, rated 100. The higher the rating, the greater the potential hazard. In addition to flame spread,

the test also measure smoke development and fuel contributed to the fire. (ASTM E84, NFPA 255,

UL 723)

stoichiometric—refers to the amount of air needed to burn the fuel (and to combustion products

formed).

stoichiometric reaction—chemical A is said to undergo a stoichiometric reaction with chemical B

when the proportions of A and B are such that there is no excess of A and B remaining after the

reaction.

stoichiometric air to fuel mass ratio—the ratio of air to fuel mass needed to burn all the fuel to

combustion.

stoichiometry—a balance chemical equation defines the stoichiometry of a reaction; stoichiometry

gives the exact proportions of the reactants for complete conversion to products, where no

reactants are remaining. Stoichiometric ratio is the ideal reaction mass fuel to oxygen (or air) ratio

and is given the symbol r.

stratification—the rising or setting of layers of smoke, according to the density or weight, with the

heaviest layer on the bottom; smoke layers usually collect from the ceiling down.

sublimation—the evaporation of molecules from a solid to form a gas in the absence of a liquid.

surface emissive power—the heat that is radiated outward from a flame per unit surface area of the

flame. It measurement and calculation units are normally kW/m . (Nolan, 2000) 2

superheat limit temperature—the temperature of a liquid above which flash vaporization can

proceed explosively.

supervisory service—the service required to monitor performance of guard patrols and the

operative condition of automatic sprinkler systems and of other systems for the protection of life and

property.

supervisory signal—a signal indicating the need of action in connection with the supervision of

guards’ tours, sprinkler and other extinguishing systems or equipment, or with the maintenance

features of other protective systems.
F-64

suppression—the sum of all the work done to extinguish an unwanted fire from the time of its

discovery until extinguishment. (NFC Online Glossary)

temperature—measurement of heat energy content for a substance/material/fluid, etc.

thermal conductivity—the property of matter that represents the ability to transfer heat by

conduction.

thermal decomposition—chemical breakdown of a material induced by the application of heat.

thermal decomposition (pyrolysis)—a process whereby chemical bonds within macromolecules

forming a solid are broken by heat and flammable vapors are released.

thermal diffusivity—ratio of a material’s thermal conductivity to the product of its heat capacity and

density. It is the measure of a material’s disposition to absorb and transmit heat to the interior of

the material.

thermal energy—energy directly related to the temperature of an object.

thermal expansion—thermal expansion becomes important when an element is heated nonuniformly, as in the case of a fire. It may cause increased axial loads in columns, resulting in earlier

buckling failure. In case of beams, however thermal expansion also affects the strain and

subsequent stress distribution through a beam section. Normally, tensile strain is increased while

compressive strain is decreased. The resulting strain distribution causes a greater deflection of the

beam at midspan. The coefficient if thermal expansion varies with temperature. In case of

concrete, thermal expansion is significantly affected by aggregate type. Thermal expansion also

affects spalling (chipping and scaling) characteristics at the surface of an element.

If the member is partially restrained axially, any added axial thrust caused by the thermal expansion

of the element will have the net effects of increasing the moment-bearing capacity (load) of the

beam. Of course, the strain caused by the thermal expansion should be considered when

calculating deflection histories of elements. Generally, beam-type assemblies are given restrained

and unrestrained fire resistance rating. 

thermal/hydraulic time line—a documented evaluation of the response of important reactor plant

parameters to a postulated transient (thermal/hydraulic analysis) with respect to the time available

to accomplish required shutdown functions. For example, the time available to establish Auxiliary

Feedwater (AFW) following a reactor scram in a PWR would be determined by a thermal/hydraulic

analysis. The objective of the thermal/hydraulic time line is to compare this time to the time needed

for operators to perform all system and equipment alignments necessary to establish a secure

source of AFW. 

Note: All operator actions delineated in alternative shutdown procedures must be supported by a

thermal/hydraulic timeline.

thermal inertia—a thermal property responsible for the rate of temperature rise, krc. Low krc -

Surface heats rapidly, fast ignition (b) High krc - Surface heats slowly, slow ignition.
F-65

thermal inertia—thermal inertia is a measure of the tendency of heat to collect on the surface of a

material. It may be a better indicator of ignitability than ignition temperature. Material such as balsa

wood and foamed plastics have low thermal inertia; their surfaces will heat up quickly, making them

easy to ignite, and to produce rapid flame spread. By contrast, materials with relatively high thermal

inertia, such as ebony wood, are difficult to ignite and do not spread fire as rapidly.

thermal inertia—thermal inertia is the resistance to temperature change in a material when the

surrounding temperature changes. The lower the thermal inertia of a material, the faster its surface

will heat, with accompanying increasing temperature. Thus response to exposing conditions is

important in terms of how quickly a combustible material reaches its ignition temperature, how fast

it burns when ignited, and the rate of flame spread across its surface. Thermal inertia also plays

an important part in determining the amount of heat absorbed by wall, ceiling, and other materials

in a compartment. Thermal inertia has an important effect on both the onset of flashover and

eventual impact of the fire.

Thermal inertia is an intrinsic material property. Its influence on the temperature of an object is

strictly a function of heat transferred to the object. As a materia’s surface is heated (or cooled),

heat is conducted to (or from) the material’s interior. At first, this heat transfer is not constant and

depends on the thermal inertia of the material. Once the rate of heat transfer from the surface to

the interior is constant , the rate of surface temperature range depends only on the conductivity of

the material, without regard to the material’s density or specific heat. For thicker materials with high

density thermal inertia, the time to reach this condition can be extensive.

thermal insulation—one or more layers of noncombustible or fire-resistant, high-density material

to reduce the passage of heat for protection against exposure of an ignition source (hot surface),

burn injuries, or heat damage. (Nolan, 2000)

thermal lag—when a fixed temperature device senses a rise in ambient temperature, the

temperature of the surrounding air will always be higher than the operating temperature of the

device itself. This difference between the operating temperature and the actual air temperature is

commonly referred to as thermal lag, an is proportional to the rate at which the temperature is

rising. (Nolan, 2000)

thermal layering—the process of gases to form layers based on temperature where the hottest

layers in a confined space are located at the highest elevations (due to lower densities) and the

lowest temperature gases are located at the lowest elevations (due to the highest densities).

(Nolan, 2000)

thermal protective clothing—the protective apparel provided for and used by firefighters and other

individuals as protective insulation against the adverse effects of heat. Generally consisting of

helmets, boots, gloves, hoods, coats, and pants. (Nolan, 2000)

thermal penetration time—time required to be conducted through a particular object, typically to

each side of the wall material.

thermal runway—an accelerating chemical reaction due to an imbalance between heat loss and

energy production.

thermocouple—device made of two dissimilar metal wires to measure temperature. 

(Quintiere, 1997). A temperature difference across an interface of two different metals causes a

voltage proportioned to the temperature difference.
F-66

thermoplastic—a polymeric solid which melts at a temperature lower that its ignition temperature.

thermoset—a polymeric solid which does not melt but decomposes to generate vapors and char.

thermal lag—the difference between the operating temperature of a fire detection device such as

sprinkler head and the actual air temperature when the device activates.

thermal transmission —among the standard criteria for the fire resistance of a building element is

its ability to insulate an adjacent space from the fire zone to prevent ignition of combustibles on the

unexposed side of the wall. The problem concerning the prediction of the element’s temperature

distribution evolves from the effects of increased temperature on thermal properties. The values

of thermal conductivity, heat capacity, and density often vary considerably with temperature and

material composition, as in the case of concrete. These terms define the thermal diffusivity, which

is critical to the analysis of heat flux through an element. 

thermoplastic cable—a cable material which will soften, flow, or distort appreciably when subjected

to sufficient heat and pressure. Examples are polyvinyl chloride and polyethylene.

Note: Cables using thermoplastic insulation are not usually qualified to IEEE Std. 383.

thermoset cable—a cable material which will not soften, flow, or distort appreciably when subjected

to heat and pressure. Examples are rubber and neoprene. 

Note: Cables using thermoplastic insulation are usually qualified to IEEE Std. 383.

time/current characteristic curve (trip curves)—a graphic illustration of the operating characteristics

of electrical protection devices (fuse, circuit breaker, or relay). The tripping characteristics of

protective devices is represented by a characteristic tripping curve that plots tripping time versus

current level. The curve shows the amount of time required for the protective device to trip at a

given overcurrent level. The larger the overload or fault current, the faster the breaker/fuse will

operate to clear the circuit (referred to as inverse time characteristics). A comparison of

characteristic trip curves is necessary to determine if proper coordination exists between devices.

TNT equivalence—the amount of TNT (trinitrotoluene) that would produce observer damage effects

similar to the explosion under consideration. For non-dense phase explosion, the equivalence has

meaning only at a considerable distance from the explosion source, where the nature of the blast

wave arising is more or less comparable with that of TNT.

total enclosure surface area—the total surface area bounding the enclosure, not including

openings.

total flooding system—a fixed suppression system which is arranged to automatically discharge a

predetermined concentration of agent into an enclosed space for the purpose of fire extinguishment

or control. 
F-67

total flooding system—a supply of dry chemical permanently connected to fixed piping and nozzles

that are arranged to discharged dry chemical into an enclosure surrounding the hazard.

The provision of a fire extinguishing agent in an enclosed area that completely fills the volume to

effect extinguishment or prevent a fire incident. They may be gaseous, liquid, or solid. Most

2

common agents are gaseous, such as carbon dioxide (CO ) or Halon; liquid types use foaming

agents, such as high expansion foam, and solid form may use dry chemical systems. Gaseous

agents require a particular concentration of agent to be achieved within the volume before

extinguishment can be achieved. Total flooding is used where it may be difficult to immediately

reach the seat of a fire, such as in machinery spaces, a computer room, and engine compartments.

Because 2 some agents (CO ) may deplete oxygen from the enclosure to extinguish the fire, special

precautions (pre-alarm, evacuation notification, reentry precautions, etc.) must be implemented

where personnel may also be present. Application of a total flooding system to an enclosure

requires the enclosure to be adequately sealed to prevent the release of the agent out of the

enclosure once it is applied.

toxicity—the nature and extent of adverse effects of a substance upon a living organism.

transmissivity—the fraction of radiant energy transmitted from a radiating object through the

atmosphere to a target after reduction by atmospheric absorption.

transient combustibles—combustibles materials that are not fixed in place or an integral part of an

operating systems or components. (Regulatory Guide 1.189)

travel distance—the length of the path a building occupant must travel before reaching an exterior

door or enclosed exit stairway, exit passageway, or horizontal exit. The total length of the exit

access.

triplex cable—a cable composed of three insulated single conductor cables twisted together.

(IEEE Std. 100-1988) 

Note: AC power cables are usually of triplex design.

trouble signal—an audible signal indicating trouble of any nature, such as a circuit break or ground,

occurring in the devices or wiring associated with a protective signaling system.

turbulent—refers to randomly fluctuating fluid motion around a mean flow.

under-ventilated—Less than stoichiometric air is available.

upper and lower flammability limits—Concentration of fuel in air in which a premixed flame can

propagate.

unconfined vapor cloud explosion (UNVC)—unconfined vapor cloud explosion where there is a

cloud of flammable gas/vapor which is within the flammable region and an ignition source creates

a deflagration seen as a fireball.

unpiloted ignition—ignition point of a material due entirely to incident heat flux on object, with no

pilot or spark present.
F-68

unprotected cable/circuit—a cable/circuit which is not provided with fire protection features sufficient

to satisfy applicable requirements (Section III.G.2 of Appendix R or Position C.5.b of SRP 9.5.1).

unresolved safety issue (USI)—according to NUREG-0933, “A Prioritization of Generic Issues,” a

USI is defined as a matter affecting of nuclear power plants that poses important questions

concerning the adequacy of existing safety requirements for which a final resolution has not yet

been developed and that involves conditions not likely to be acceptable over the lifetime of the

plants affected.

upper flammability limit—the highest concentration of fuel in air at normal temperatures and

pressure that can support flame propagation is known as the upper flammability limit (UFL) or upper

explosive limit (UEL).

vapor barrier—that material used to prevent or substantially inhibit the transfer of water, corrosive

liquids and steam or other hot vapors from the outside of a garment to the wearer's body. 

vaporization temperature—the temperature of a vaporizing fuel while burning, or needed to cause

vaporization.

vent, heat, and smoke—an assembly rated for the release of heat or smoke from a fire event. Heat

and smoke vents are commonly provided in the roofs of buildings. They may be activated by means

of automatic detection or constructed of materials that cause the material to melt from the heat of

the fire and create an opening for venting. The sizing of heat or smoke vents should be based on

the anticipated fire event.

vent flow—if there is an opening to the adjacent room or out to the atmosphere, the smoke will flow

out through it as soon as the hot layer reaches the top of the opening. Often, the increasing heat

in the enclosure will cause the breakage of windows and thereby create an opening.

ventilation—the process of supplying or removing an atmosphere to or form any space by natural

or mechanical means.

ventilation factor—the parameter controlling smoke flow rate through a door or window

ventilation-limited or ventilation-controlled—state of a compartment fire where the air supply is

limited; smoke gases will have nearly zero oxygen left; under-ventilated.

ventilation-controlled fire—a fire of which the heat release rate or growth is controlled by the amount

of air available to the fire. (NFC Online Glossary)

ventilation, mechanical—the use of exhaust fans, blowers, air conditioning systems, or smoke

ejectors to remove products of combustion (smoke, heat, gases) from an area affected by a fire

event. (Nolan, 2000)

ventilation rate—ventilation rate is based on air changes per hour and is calculated by the use of

100-percent outside air for the supply air that is exhausted. Air changes per hour is calculated on

the basis of the maximum aggregate volume (under normal operating conditions) of the space to

be ventilated. (NFC Online Glossary)
F-69

venting, fire—the escape of smoke, noxious or toxic fumes, and heat through openings in a building

provided as part of the structure (a chimney) or instituted during emergency fire-fighting actions for

the removal of hot gases and smoke particles. In fire conditions, it is generally accepted that the

efficient venting of heat, hot gases, and smoke reduces the lateral spread and subsequent damage

and enables firefighters to more easily enter a building on fire and begin fire protection measures.

In order for roof or ceiling vents to operate efficiently, there has to be an adequate source of low

level replacement air. Ventilation through the top of a structure or its roof vents or similar devices

(skylights) is called vertical ventilation or top ventilation. (Nolan, 2000)

view factor—the ratio of the incident radiation received by a surface to the emissive power from the

emitting surface per unit area.

visibility—the maximum distance one can recognize objects, often referring to an exit sign in a

smoke-filled compartment.

voltage—the effective root-mean-square (rms) potential between any two conductors or between

a conductor and ground. Voltages are expressed in nominal values unless otherwise indicated.

(IEEE Std 100-1988)

Clarification: The electrical force that causes free electrons to move from one atom to another.

Similar to pressure in a water pipe.

water curtain—a screen or wide angle spray of water that is set up and used to protect exposures

from fire effects mainly from radiated heat, smoke, and billowing flames. It normally consists of open

or closed sprinkler heads or perforated pipes installed on the exterior of a building at eaves,

cornices, window openings, or peaked roofs under manual control, or installed around the openings

in floors or walls of a building with the water supply under thermostatic control. Manual firefighting

operations may also provide and position water spray nozzles to provide a water curtain to protect

exposures. It may also be called a water screen.

water damage—the damage sustained to a property as a direct result of water-based fire-fighting

efforts or because of leakage from a fixed water-based suppression system (sprinkler system).

water flow alarm—a sounding device activated by a water-flow detector or alarm check valve and

arranged to sound an alarm that is audible in all living areas over background noise levels with all

intervening doors closed.

water flow detector—an electric signaling indicator or alarm check valve actuated by water flow in

one direction only.

water flow switch—an assembly approved for the service and so constructed and installed that any

flow of water from sprinkler system equal to or greater than that from a single automatic sprinkler

of the smallest orifice size installed on the system will result in activation of this switch and

subsequently indicate an alarm condition.

water flow test—an evaluation of water sup-plies and a piping distribution network to deter-mine

whether it is of sufficient capacity and pressure to provide or meet fire protection needs or

requirements. Static pressure, residual pressure, hydraulic profile, and flow rates may be obtained

during water flow tests. (Nolan, 2000)
F-70

water horsepower—power necessary to move water.

water supply—source of water for fire protection purposes typically described in terms of volume,

flow rate, and pressure.

Watt—Power necessary to move a weight of 1 newton a distance of 1 meter in i second. One

horsepower is equal to 746 watts.

wet chemical—normally a solution of water and potassium carbonate-based chemical, potassium

acetate-based chemical, potassium citrate-based chemical, or a combination thereof that forms an

extinguishing agent.

wet chemical—a solution of water and potassium carbonate-based chemical, potassium acetatebased chemical, or a similar combination that is used as a fire extinguishing agent. Its application

may cause corrosion or staining of the protected equipment if not removed. Wet chemical solutions

are generally considered relatively harmless and normally have no lasting significant effects on

human skin, the respiratory system, or personal clothing. (Nolan, 2000)

wet chemical fire suppression system—an automatic fire suppression system that uses a liquid

agent. It is applied through a system of piping and nozzles with an expellant gas from a storage

cylinder. It is usually released by automatic mechanical thermal linkage. The agent leaves a residue

that is confined to the protected area that must be removed after application. Primarily applied to

having cooking range hoods and ducts and associated appliances. The wet chemical agent consist

of water and usually potassium carbonate or potassium acetate. (Nolan, 2000)

wetting agent—a wetting agent is a chemical compound that, when added to water in amounts

indicated by the manufacturer, will materially reduce the water’s surface tension, increase its

penetrating and spreading abilities, and might also provide emulsification and foaming

characteristics. Decreased surface tension disrupts the forces holding the film of water together,

thereby allowing it to flow and spread uniformly over solid surfaces and to penetrate openings and

recesses over which it would normally flow. Water treated in this manner not only spreads and

penetrates, but displays increased absorptive speed and superior adhesion to solid surfaces. Water

normally has a surface tension of 73 dynes per centimeter and wetting agents can lower it to about

25 dynes per centimeter. Leaks in piping connections and pump packing can occur that would not

have occurred if the wetting agent had not been used. Visual inspection should be made during wet

water operations. Wet water should be applied directly to the surface of the combustible. These

agents do not increase the heat absorption capacity of water, but the greater spread and

penetration of the wet water increase the efficiency of the extinguishing properties of water, as more

water surface is available for heat absorption and run-off is decreased. Therefore they enhance fire

control and suppression applications, especially for three dimension fires. Wetting agents are

broadly defined as being surfactants (surface acting agents). All wetting agents are concentrated

and are mixed with a liquid at varying percentages (usually 1 to 2 per-cent). The wetting agent can

be liquid or pow-der. The liquid into which it is mixed for firefighting purposes is water. However,

the primary sales for some wetting agents are for use as a carrier for liquid fertilizers, fungicides,

insecticides, and herbicides. These wetting agents can be, and are, used for firefighting purposes.

They do not have additives that protect tanks, pumps, valves, and bushings, etc., so it is

recommended that unused mixtures be drained out of the tank and a flush of all parts made with

plain water. With all wetting agents, hard water usually requires a greater amount of additive to

produce the same results. Wetting agents designed for fire department use will normally contain

rust inhibitors to protect the tank, pump, piping, and valves. Generally, the mixture loses some of
F-71

its rust-inhibiting characteristics if left in the tank. Wetting agents are best used as a soaking or

penetrating agent for a three-dimensional burning mass such as wild-land fuels, coal piles, sawdust,

cotton (bales, bedding, upholstery), rags, paper, etc. These agents are used very effectively on

smoldering or glowing combustibles. All of the commercially available products that fall into the preceding category will satisfactorily suppress Class A fires. (Nolan, 2000)

wet water—firefighting water to which a wet-ting agent has been added to reduce its surface

tension and increase its penetrating power into the fire environment. Wet water is useful in

congested environments where normal water application may be blocked or restricted. Wet water

can more easily seep into inaccessible areas. 

worst case scenario—a scenario resulting in the worst consequence as defined by the stakeholders

or a code. The criteria must be explicitly stated because worst case conditions for life safety and

property protection might be incompatible.

worst credible fire—For a specific site, a fire, as defined by the stakeholders or a code, that can be

reasonably expected to result in unfavorable consequences equal to or less severe than those

resulting from a worst case scenario.

yield strength—yield strength, both compressive and tensile, is degraded by an increase in

temperature. This loss of strength can result in the mechanical failure of an element at an elevated

temperature. The temperature dependence of the yield strength is a multi-variate function.

zone smoke control—a smoke control system that provides smoke exhaust for a smoke zone and

pressurization of all adjacent smoke control zones, thereby providing removal of smoke from the

primary area of concern and using preventive measures to avoid additional smoke infiltration to

primary area of concern. (Nolan, 2000)
F-72

References

ASTM E 84-98 , “Standard Test for Surface Characteristics of Building Materials,” ASTM Fire Test ,1

Standard, Fifth Edition, American Society of Testing and Materials, West Conshohocken,

Pennsylvania, 1999, pp. 765-780.

Friedman, R., Principles of Fire Protection Chemistry and Physics, 3 Edition, National Fire rd

Protection Association, Quincy, Massachusetts, 1997.

Generic Letter 88-20, “Individual Plant Examination for Severe Accident Vulnerabilities,” November

23, 1988.

Generic Letter 81-12, “Fire Protection Rule (45 FR 76602, November 19, 1980),” February 20,

1981, and Clarification Letter, March 1982.

IEEE Standard 383, “IEEE Standard for Type Test of Class IE Electric Cables, Field Splices, and

Connections for Nuclear Power Generating Stations,” Institute of Electrical and Electronics

Engineers.

McGraw-Hill Dictionary of Scientific and Technical Terms, 5 Edition, S.P. Parker, Editor in Chief, th

McGraw-Hill, Inc., New York, 1993.

NEMA Standard FU-1, “Low Voltage Cartridge Fuses,” National Electrical Manufacturers

Association, 1986

NFC Online Glossary, National Fire Protection Association, Quincy, Massachusetts.

NFPA 30, “Flammable and Combustible Liquids Code,” National Fire Protection Association,

Quincy, Massachusetts.

NFPA 220, “Standard on Types of Building Construction,” National Fire Protection Association,

Quincy, Massachusetts.

NFPA 255, “Standard Method of Test of Surface Burning Characteristics of Building Materials,”

National Fire Protection Association, Quincy, Massachusetts.

NFPA 805, “Performance-Based Standard for Fire Protection for Light Water Reactor Electric

Generating Plants,” National Fire Protection Association, Quincy, Massachusetts.

Nolan, D.P., Encyclopedia of Fire Protection, Delmar Publishers, Albany, New York, 2000.

Quintiere, J.G., Principles of Fire Behavior, Delmar Publishers, Albany, New York, 1997.

Regulatory Guide 1.189, “Fire Protection for Operating Nuclear Power Plants,” April 2001.

UL 723, “Standard for Test for Surface Burning Characteristics of Building Materials ,” Underwriters

Laboratories, Inc.

Webster Ninth New Collegiate Dictionary.
G-1

APPENDIX G. ABBREVIATIONS USED 

IN FIRE PROTECTION ENGINEERING

The purpose of this appendix is to provide abbreviations of the numerous engineering and scientific

terms that appear in fire protection printed and electronic information. This collection has been

complied from various sources [e.g., National Fire Protection Association (NFPA), Society of Fire

Protection Engineers (SFPE)]. No one abbreviation is recommended to the exclusion of another

because the same abbreviation may with equal validity apply to two or more terms. The following

abbreviations are commonly used in the field of fire science, engineering, and technology.

ACI American Concrete Institute

ACMV Air Conditioning and Mechanical Ventilation

ACV Alarm Check Valve

ADA Americans with Disabilities Act

ADAAG Americans with Disabilities Act Accessibility Guidelines

ADD Actual Delivered Density

AFA Automatic Fire Alarm

AFAA Automatic Fire Alarm Association (USA)

AFD Aspirating Fire Detection

AFFF Aqueous Film-forming Foam (fire suppression agent)

AFP Active Fire Protection

AFSA American Fire Sprinkler Association

AFT Adiabatic Flame Temperature

AHJ Authority Having Jurisdiction

AIA American Insurance Association

AIChE American Institute of Chemical Engineers

AISC American Institute of Steel Construction

AISI American Iron and Steel Institute

AIT Autoignition Temperature

ALC Approximate Lethal Concentration

ALV Alarm Valve

ANSI American National Standards Institute

AOV Air-Operated Valve

AP Annunciator Panel (fire alarm)

AR-AFFF Alcohol Resistant-Aqueous Film Forming Foam (fire suppression agent)

ARC Alcohol-Resistant Concentrates

ARV Air Release Valve

AS Automatic Sprinkler

ASCE American Society of Civil Engineers

ASD Automatic Smoke Detection

ASET Available Safe Egress Time

ASHRAE American Society of Heating, Refrigerating, and Air Conditioning Engineers

ASME American Society of Mechanical Engineers

ASMET Atria Smoke Management Engineering Tools

ASRS Automatic Storage and Retrieval System

ASSE American Society of Safety Engineers

AST Aboveground Storage Tank

ASTM American Society for Testing and Materials
G-2

ATC Alcohol Type Concentrate

ATS Automatic Transfer Switch

AWG American Wire Gage

BCMC Board of Coordination of the Model Code

BFRL Building and Fire Research Laboratory (USA)

BHF Bureau of Home Furnishings

BHP Brake Horsepower

BI Barrier Integrity

BLEVE Boiling Liquid Expanding Vapor Explosion

BNBC BOCA National Building Code

BNFPC BOCA National Fire Prevention Code

BOCA Building Officials and Code Administrators International, Inc.

BOMA Building Owners and Managers Association

BOP Blowout Preventor (valve)

BP Boiling Point Temperature

BSD Beam Smoke Detector

BTU British Thermal Unit

CABO Council of American Building Officials

CAFS Compressed Air Foam System

CAFSS Clean Agent Fire Suppression System

CCDS Critical Combustible Data Sheet

CCFM Consolidated Compartment Fire Model (computer code developed by NIST)

CCPA Center of Chemical Process Safety (AIChE)

CDG Carbon Dioxide Generation Calorimetry

CDS Chemical Data System

CFAST Consolidated Model of Fire Growth and Smoke Transport 

(computer code developed by NIST)

CFD Computational Fluid Dynamics

CFI Certified Fire Investigator (NFPA)

CFPE Certified Fire Plan Examiner (NFPA)

CFPS Certified Fire Protection Specialist (NFPA)

CFR Code of Federal Regulation

CFSI Congressional Fire Service Institute (USA)

CGA Compressed Gas Association (USA)

CHF Critical Heat Flux

CIB Conseil International du Batiment

CLE Coefficient of Linear Expansion

CNG Compressed Natural Gas

CO Carbon Monoxide

CO2 Carbon Dioxide

COHB Carboxyhemoglobin

COR Code of Record

CSAA Central Station Alarm Association

CSDS Critical Screen Data Sheet

CSI Construction Specifications Institute

CSP Certified Safety Professional (Board of Certified Safety Professionals, USA)
G-3

CSPS Consumer Product Safety Commission (USA)

CSRF Construction Sciences Research Foundation

CV Check Valve

CVD Combustible Vapor Dispersion

DACR Digital Alarm Communicator Receiver

DACS Digital Alarm Communicator System

DACT Digital Alarm Communicator Transmitter

DARR Digital Alarm Radio Receiver

DARS Digital Alarm Radio System

DART Digital Alarm Radio Transmitter

DC Dry Chemical (fire extinguisher agent)

DCVA Double Check Valve Assembly

DD Duct Detector

DDT Deflagration-to-Detonation Transition

DH Double Outlet, Fire Hydrant

DID Defense-in-Depth

DIERS Design Institute for Emergency Relief Systems

DP Dry Pipe or Dry Pendant Sprinkler

DPV Dry Pipe Valve

EC Expansion Coefficient

EDS Explosive Detection System

EEBD Emergency Egress Breathing Device

EFP Electric Fire Pump

EFS Equivalent Fire Severity

ELO Extra Large Orifice (sprinkler)

EMD Electric Motor Driven

EOLR End-of-Line Resistor

EPA Environment Protection Agency (USA)

ER Electrical Resistance

ERFBS Electric Raceway Fire Barrier System

ESF Engineered Safety Feature

ESFR Early Suppression Fast Response (sprinkler)

ESS Emergency Shutdown System

ETA Event Tree Analysis

ESW Emergency Service Water

FA Fire Alarm

FACP Fire Alarm Control Panel

FAG Fire Alarm Group

FAST Fire Growth and Smoke Transport (computer code developed by NIST)

FB Fire Brigade

FCIA Fire Compartment Interaction Analysis

FCP Fire Control Plan

FD Fire Department, Fire Damper, Fire Detection

FDC Fire Department Connection, Functional Design Criteria

FDI Fire Detection Institute (USA)

FDPC Fire Department Pumper
G-4

FDU Fire Detecting Unit

F&E Fire and Explosion

FE Fire Endurance, Fire Escape, Fire Extinguisher

FDMS Fire Data Management System

FDS Fire Dynamics Simulator (CFD computer code developed by NIST)

FED Fractional Effective Dose

FEDB Fire Event Data Base

FEHM Fire and Explosion Hazard Management

FEMA Federal Emergency Management Agency (USA)

FERP Fire Emergency Response Plan

FFFP Film-forming Fluoroprotein foam (fire suppression foam agent)

FFM Furniture Fire Model

FFR Fire-Resistance Rating

FGC Fireground Command

FH Fire Hydrant, Fire Hose

FHA Fire Hazards Analysis or Assessment

FHAR Fire Hazards Analysis Report

FHR Fire Hose Reel

FHSR Fire Hazards Safety Report

FHZ Fire Hazard Zone

FID Fractional Incapacitating Dose

FIDO Fire Incident Data Organization (NFPA)

FIGRA Fire Growth Rate Index

FIVE Fire Induced Vulnerability Evaluation

FL Friction Loss

FLC Friction Loss Coefficient

FLD Fractional Lethal Dose

FLED Fire Load Energy Density

FM Fire Modeling

FMANA Fire Marshals Association of North America

FMEA Failure Mode and Effect Analysis

FMRC Factory Mutual Research Corporation (USA)

FP Fire Protection, Fire Pump, Flash Point, Flammability Parameter

FPE Fire Protection Engineer

FPETOOL Fire Protection Engineering Tools for Hazard Estimation 

(computer code developed by NIST)

FPFG Fire Protection Focus Group

FPFI Fire Protection Functional Inspection

FP H F ire P u m p H o u se

FPI Fire Propagation Index

FPR Fire Protection Rating

FP S F ire P ro te c tion Sy s te m

FP S S F ire P ro te c tion and S upporting Sy s te m s

FPWG Fire Protection Working Group

FR Fire-Retardant

FRAM Fire Risk Assessment Method

FRG Fire Resisting Glazing

FRIS Fire Research Information Services (NIST)

FS Flow Switch (water)
G-5

FSAR Final Safety Analysis Report

FSBBS Fire Safety Bulletin Board System (NIST)

FSCS Fire Fighter’s Smoke-Control Station

FSES Fire Safety Evaluation System

FSHA Federal Hazardous Substance Act

FSI Flame Spread Index

FSM Fire Screening Methodology

FSR Flame Spread Rating

FSS Fire Suppression System

FSS Fire Systems Services

FSSD Fire Safe Shutdown

FTA Fault Tree Analysis

FW Fire Water

FWP Firewater Pump

FWS Firewater System

GBHP Gross Break Horsepower

GC/MSGas Chromatography/Mass Spectrometry

GN2 Gaseous Nitrogen

GPM Gallon Per Minute

GTR Gas Temperature Rise Calorimetry

HAD Heat-Activated Device

HAG Halon Alternative Group

HALON Halogenated Hydrocarbon (Gaseous fire suppression agent)

HAZOP Hazard and Operability Study

HC Hose Cabinet, Hose Connection

HCFC Hydrpchlorofluorocarbon

HCN Hydrogen Cyanide

HCP Halon Control Panel

HCS Hydrogen Control System

HD Heat Detector, Heat of Decomposition

HEPA High-Efficiency Particulate Air

HFC Hydrofluorocarbon

HG Hydrogen Gas

HGL Hot Gas Layer

HIFT High Intensity Fire Testing

HMIS Hazardous Materials Inventory Statement

HMIS Hazardous Materials Identification System

HMMP Hazardous Materials Management Plan

HMR Hazardous Materials Regulations

HP Heat of Polymerization

HPM Hazardous Production Materials

HPR Highly Protected Risk

HRC Halon Recycling Corporation

HRP Heat Release Parameter

HRR Heat Release Rate

HSSC Highly Safety Significant Component

HSSD High Sensitivity Smoke Detection
G-6

HST Hot-Smoke Test

HTA High Temperature Accelerant

HTF Heat Transfer Fluid

HTOC Halon Technical Options Committee

HVAC Heating, Ventilation, and Air Conditioning

HX Heat Exchanger

IAFC International Association of Fire Chiefs

IAFSS International Association of Fire Safety Science

I&C Instrumentation and Controls

ICBO International Conference of Building Officials

ICC International Code Council

ICE International Electrotechnical Commission

ICS Incident Command System

IDC Initiating Device Circuits

IE Initiating Events

IEC International Electrotechnical Commission

IEEE Institute of Electrical and Electronic Engineers, Inc.

IFCI International Fire Code Institute

ILBP In-Line Balanced Proportioner

IP Inert Point, Inspection Procedure

IPA Integrated Plant Assessment

IR Infrared

IRI Industrial Risk Insurers

ISDS Ignition Source Data Sheet

ISI Inservice Inspection

ISO International Organization for Standardization

IST Inservice Testing

ITM Inspection, Testing, and Maintenance

JCAHO Joint Commission on Accreditation of Health Organizations

LBTF Large Building Test Facility

LC Limited-Combustible

LC50 The Concentration Lethal 50 Percent of a Population

LD50 Respiratory Depression

L/D Length to Diameter

LDH Large Diameter Hose

LEL Lower Explosive Limit

LES Large Eddy Simulation

LFG Liquefied Flammable Gas 

LFL Lower Flammability Limit

LFS Limiting Fire Scenarios

LHD Linear Heat Detection

LIFT Lateral Ignition and Flame Spread Test (ASTM E1321)

LNG Liquefied Natural Gas

LO Large Orifice (sprinkler)

LOC Limiting Oxidant Concentration, Lower Oxygen Concentration, Loss of Containment

LOI Limiting Oxygen Index
G-7

LOX Liquid Oxygen

LP Liquefied Petroleum

LPG Liquefied Petroleum Gas, Liquefied Propane Gas

LRFD Load and Resistance Factor Design

LSC Life Safety Code (NFPA 101) ®

LOST Lube Oil Storage Tank

M/A Manual or Automatic

MAC Manual Activation Call Point (fire alarm)

MAG Maximum Allowable Concentration

MC Moisture Content

MCFL Maximum Credible Fire Loss

MCSC Model Codes Standardization Council

MDH Medium Diameter Hose

MEC Minimum Explosive Concentration

MEFS Maximum Expected Fire Scenario

MESG Maximum Experimental Safe Gap

MFL Maximum Allowable Fuel Loading

MIC Minimum Ignition Current, Microbiologically Influenced Corrosion

MIE Minimum Ignition Energy

MLR Mass Loss Rate

MOC Maximum Allowable Oxygen Concentration

MOD Mass Optical Density

MOV Motor-Operated Valve

MPFL Maximum Possible Fire Loss

MPS Manual Pull Station

MPV Minimum Proper Value

MS Mitigating Systems

MSDS Material Safety Data Sheet

NAC Notification Appliance Circuits

NAFED National Association of Fire Equipment Distributors (USA)

NBFAA National Burglar and Fire Alarm Association, Inc. (USA)

NBFU National Board of Fire Underwriters

NBHP Net Break Horsepower

NBS National Bureau of Standards (now NIST)

NC Non-Combustible, Non-Compliance

NCEES National Council of Examiners for Engineering and Surveying

NCHRR Normalized Chemical Heat Release Rate

NCSBCS National Conference of States on Building Codes and Standards

NEC National Electrical Code (NFPA 70) ®

NEMA National Electric Manufacturers Association

NFC National Fire Code

NFD Nominal Fire Duration

NFDC National Fire Data Center (USA)

NFDRS National Fire Danger Rating System (USA)

NFIC National Fire Information Council (USA)

NFIRS National Fire Incident Reporting System (FEMA/USFA)

NFPA National Fire Protection Association (USA)
G-8

NFPRF National Fire Protection Research Foundation (USA)

NFR Non-Fire Retardant

NFSA National Fire Sprinkler Association (USA)

NHT National Hose Thread

NIBS National Institute of Building Sciences (USA)

NICET National Institute for Certification in Engineering Technologies (USA)

NIFC National Interagency Fire Center (USA)

NIOSH National Institute for Occupation Safety and Health (USA)

NIST National Institute of Standards and Technology (USA)

NLE Normal Loss Expectancy

NPP Neutral Pressure Plane 

NPSH Net Positive Section Head

NPSHA Net Positive Section Head Available

NPSHR Net Positive Section Head Required

NRS Nonrising Stem (gate valve)

NRTL Nationally Recognized Testing Laboratory

NS Non-Sprinklered

NSC National Safety Council

NST National Standard Thread

NTP Normal Temperature and pressure

NUMARC Nuclear Management and Resources Council

OC Over Compliance

OD Optical Density, Outer Diameter

ODP Ozone Depletion Potential

ODS Ozone Depleting Substance

OI Oxygen Index

OS Open Sprinkler

OSHA Occupational Safety and Health Administration (USA)

OSR Operational Safety Requirement

OS&Y Outside Stem and York or Outside Screw and Yoke (valve)

OWSI Open Web Steel Joist

PASS Personal Alert Safety System

PAV Pre-Action Valve

PCV Pressure Control Valve

PDP Pump Discharge Pressure

PDS Point of Demand Supply

PE Professional Engineer (NCEES)

PEL Permissible Exposure Limit

PFC Perfluorocarbon

PFDAS Plant Fire Detection and Alarm System

PFHA Preliminary Fire Hazard Analysis

PFP Passive Fire Protection

PFPCDS Plant Fire Protection Carbon Dioxide Subsystem

PFPHS Plant Fire Protection Halon Subsystem

PFPS Plant Fire Protection System

PFPWS Plant Fire Protection Water Subsystem

PHA Process Hazard Analysis
G-9

PHRR Peak Heat Release Rate

P&IDs Piping & Instrumentation Diagram, Piping & Instrumentation Drawing,

Process & Instrumentation Diagram 

PIM Performance Integrity Measure

PIV Post Indicator Valve

PLFA Power-Limited Fire Alarm (circuits or cables)

PLG Pressure Liquefied Gas

PML Probable Maximum Loss

pphm Parts Per Hundred Million

ppm Parts Per Million

PPV Positive Pressure Ventilation

PRA Probabilistic Risk Assessment

PRV Pressure Relief Valve

PS Pressure Switch, Pull Station (fire alarm, manual)

PSA Probabilistic Safety Analysis or Probabilistic Safety Assessment

PSF Potential of Fire Spread

PSV Pressure Safety Valve

PZR Pressurizer

QH Quadruple Outlet, Fire Hydrant

QOD Quick Opening Devices

QR Quick-Response (sprinkler)

QRA Quantitative Risk Analysis or Quantitative Risk Assessment

QRES Quick-Response Early Suppression (sprinkler)

RARSR Radio Alarm Repeater Station Receiver

RAS Radio Alarm System

RASSR Radio Alarm Supervising Station Receiver

RAT Radio Alarm Transmitter

RCAP Root Cause Analysis Report

RDD Required Delivered Density

RF Radio Frequency

RHR Rate of Heat Release

RI/PB FP Risk-Informed and Performance-Based Fire Protection

RMV Respiratory Minute Volume

ROR Rate of Rise

RPE Respiratory Protection Equipment

RPM Revolution Per Minute

RPZ Reduced Pressure Zone (water)

RSET Required Safe Egress Time

RTI Response Time Index

RV Riser Valve, Relief Valve

RVP Reid Vapor Pressure
G-10

SAWG Severe Accident Working Group

SBC Standard Building Code

SBCCI Southern Building Code Congress International, Inc.

SCBA Self-Contained Breathing Apparatus

SCFM Standard Cubic Feet Per Minute

SD Smoke Detector, Smoke Damper

SDH Small Diameter Hose

SDI Smoke Density Index or Smoke Developed Index or Smoke Damage Index

SDP Significance Determination Process

SEA Specific Extinction Area

SEI Structural Engineering Institute (USA)

SEP Surface Emissive Power

SEPSS Stored Emergency Power Supply System

SF Safety Factor

SFP Steam Fire Pump

SFPC Standard Fire Prevention Code

SFPE Society of Fire Protection Engineers (USA)

SHEVS Smoke and Heat Exhaust Ventilation System

SIS Safety Instrumented Systems

SL Stoichiometric Limit

SLC Signaling Line Circuits

SMS Smoke Management System

SMACNA Sheet Metal and Air Conditioning Contractors’ National Association, Inc. (USA)

SOP Standard Operating Procedures

SPR Smoke Production Rate

SRV Safety Relief Valve

STA Success Tree Analysis

STD Standard Orifice Sprinkler

STP Standard Temperature and Pressure

SSC System, Structure, and/or Component

SSP Standard Spray Pendant (sprinkler head)

SSU Standard Spray Upright (sprinkler head)

STI Steel Tank Institute

STTC Standard Time-Temperature Curve (ASTM E119)

SV Smoke Vent, Safety Valve

SW Service Water

TC Thermocouple

TDL Threshold Damage Limit

TDR Tender Delivery Rate

TGA Thermogravimetric Analysis

THC Total Unburned Hydrocarbons

THR Total Heat Released

TLV Threshold Limit Value

TNT Trinitrotoluene

TPP Thermal Protective Performance

TR Temperature Rise

TRP Thermal Response Parameter

TSR Total Smoke Released
G-11

TTI Time to Sustained Ignition

TV Tidal Volume

TWA Time Weighted Average

UBC Uniform Building Code

UEL Upper Explosive Limit

UFC Uniform Fire Code

UFL Upper Flammability Limit

UFSAR Updated Final Safety Analysis Report

UL Underwriter’s Laboratories, Inc.

UPS Uninterruptible Power Supply

USFA United States Fire Administration

UST Underground Storage Tank

UV Ultraviolet

UVCE Unconfined Vapor Cloud Explosion

VESDA Very Early Smoke Detection and Alarm

VCE Vapor Cloud Explosion

VOC Volatile Organic Compound

VSP Volume of Smoke Production

WATS Wide Area Telephone Service

WCCE Worst Case Creditable Event

WE Wet Chemical (fire extinguisher agent)

WH Wall Hydrant

WHMIS Workplace Hazardous Materials Identification Systems

WHP Water Horsepower

WIC Withstand and Interrupting Current

WOBO World Organization of Building Officials

WOM Water Oscillating Monitor

WPIV Wall Post Indicator Valve

WSO World Safety Organization

ZV Zone Valve (sprinkler)

Licensee event reports (LERs) are form reports that are often accompanied by narratives, 1

which licensees and the nuclear industry submit to the U.S. Nuclear Regulatory Commission,

in accordance with the regulatory requirements following the occurrence of reportable events. 

Oak Ridge National Laboratory (ORNL) maintains all LERs in a searchable database for use

of NRC and its licensees.

H-1

APPENDIX H. SELECTED U.S. COMMERCIAL

NUCLEAR POWER PLANT FIRE INCIDENTS

H.1 Introduction

Over the past few decades, a number of large fires have occurred in commercial nuclear power

plants (NPPs), both in the United States and abroad. Particularly notable among the U.S.

events was the cable spreading room (CSR) and reactor building fire at Browns Ferry Nuclear

Power Plant (BFNP) in 1975, in which a single fire partially or totally disabled numerous safetyand nonsafety-related systems.

Empirical data indicate that a nuclear facility will experience event precursors (in this case,

smaller fires that have no impact on nuclear safety) more frequently than actual fires affecting

nuclear safety equipment (such as the BFNP fire). Many argue that no fire in an NPP is without

nuclear safety implications because every fire threatens safety through its effects on either

equipment or personnel operating the facility. Nevertheless, the industry expects an NPP to

experience a fire that affects nuclear safety equipment every 6 to 10 years (Ramsey and

Modarres, 1998).

The remainder of this appendix provides a summary table and detailed narrative discussions

concerning the major fires that have occurred at U.S. commercial NPPs since 1968. The

specific incidents included are those fires that led to severe or widespread damage and those

that challenged nuclear safety. Additional detail concerning these fire incidents is available in

the NRC inspection reports and licensee event reports (LERs) .

1

These general descriptions are provided for information only. The events can be used to

develop real-life example problems for use with the fire dynamics spreadsheets.

Reference

Ramsey, C.B., and M. Modarres, Commercial Nuclear Power Assuring Safety for The Future,

John Wiley & Sons, Inc., New York, 1997.
H-2

Table H.1-1. Summary of Selected U.S. Commercial Nuclear Power Plant Fire Incidents

Plant Date of Incident Description of Fire Incident

San Onofre Nuclear

Generating Station,

Unit 1

February 7 and

March 12, 1968

Two similar incidents involving self-ignited cable fires

took place within a 5-week period. On February 7,

1968, San Onofre Nuclear Generating Station (SONGS)

Unit 1 experienced a self-ignited cable fire adjacent to a

containment penetration and on March 12, 1968,

another self-ignited cable fire occurred in a 480-volt

switchgear room. These fires showed significant fire

propagation beyond the initiating cable. The licensee

reported that three horizontal stacked cable trays were

burning at the time that the fire brigade arrived on the

scene (several minutes after the apparent time of

ignition).

Browns Ferry Nuclear

Power Plant, Unit 1 

March 22, 1975 A cable spreading room and reactor building fire

challenged nuclear safety and led to important changes

in the NRC’s fire protection program.

North Anna Power

Station, Unit 2

July 3, 1981 A severe fire involved a large transformer, but did not

affect any safety-related components or electrical

circuits.

Rancho Seco Nuclear

Generating Station

March 19, 1984 A hydrogen fire and explosion occurring in the turbine

building.

Waterford Steam

Electric Generating

Station, Unit 3

June 26, 1985 This main feedwater pump fire involved operator error

leading to a loss of redundant trains. The plant operator

at the scene called the control room with the wrong

pump tag number. This error resulted in the undamaged

pump being shut down from the control room.

Fort St. Vrain Nuclear

Generating Station

October 2, 1987 This large turbine building fire involved hydraulic oil and

affected control room habitability as a result of smoke

ingress.

Oconee Nuclear

Station, Unit 1

January 3, 1989 A fire in a nonsafety-related switchgear led to equipment

failure. Smoke from fire propagates outside fire area

(e.g., smoke control room from turbine building

switchgear fire). In this incident equipment was

unavailable to use water to suppress the fire, and fire

induced independent failures challenge the operator.

H.B. Robinson Steam

Electric Plant, Unit 2

January 7, 1989 This event involved hydrogen fires at multiple locations

during an outage because of maintenance crew error.

Calvert Cliffs Nuclear

Power Plant, Unit 2

March 1, 1989 This incident involved multiple initial fires, including a

small fire in the control room.

Shearon Harris Nuclear

Power Plant

October 9, 1989 This incident involved multiple initial and secondary fires

involving one of the main transformers and electrical

equipment in the turbine building.
Table H.1-1. Summary of Selected U.S. Commercial Nuclear Power Plant Fire Incidents

Plant Date of Incident Description of Fire Incident

H-3

Salem Nuclear

Generating Station,

Unit 2

November 9, 1991 This turbine building fire was caused by a turbine blade

failure and ejection.

Waterford Steam

Electric Generating

Station, Unit 3

June 10, 1995 This incident involved a 4,160V switchgear cabinet fire.

The cause of the fire was improper automatic bus

transfer due to slow circuit breaker caused by hardened

grease. A fire initiated inside a switchgear propagates

outside of the switchgear boundary (e.g., arcing, smoke,

ionized gases damaged four more switchgear cabinets;

and overhead cables are damaged in part from failure of

a cable tray fire barrier). The fire burned over an hour.

The fire induced and independent equipment failures

that challenge the operator.

Palo Verde Nuclear

Generating Station,

Unit 2

April 4, 1996 This incident involved multiple initial fires, including a

small fire in the main control room.

San Onofre Nuclear

Generating Station,

Unit 3

February 3, 2001 This incident involved a circuit breaker fault resulted in

a fire, loss of offsite power, and reactor trip. The

damage extended to the associated electrical bus and

cable trays in the switchgear room. A subsequent

failure to start the turbine emergency DC lubricating

(lube) oil pump resulted in extensive turbine damage. In

this event, a 4.16-kV switchgear fault had an explosive

release of energy and the ensuing fire was substantial

enough to damage other plant equipment.
Table H.1-1. Summary of Selected U.S. Commercial Nuclear Power Plant Fire Incidents

Plant Date of Incident Description of Fire Incident

H-4

Point Beach Nuclear

Plant, Unit 1

April 24, 2001 A small fire originated as the result of a short in a

12-Vdc communication box during a refueling outage in

the steam generator (S/G) vault on the access platform

to the primary side manway covers. The fire consumed

a bag of rags and testing equipment debris, and lasted

for approximately 23 minutes. After multiple failed

attempts in which the fire brigade discharged

approximately 70 pounds of dry chemical (three portable

fire extinguishers), the fire was finally extinguished using

15–20 gallons of water. The dry chemical fire

extinguishing agent was dispersed through large areas

of the S/G and reactor coolant pump (RCP) vaults.

Certain chemicals in the extinguishing agent can result

in potential stress corrosion cracking on the exposed

stainless steel pipe and tube surfaces in the presence of

halogens (chlorides, fluorides, and sulfates) with high

temperatures (greater than 250 °F) and contamination

of motors, air-operated valves, safety-related snubbers,

and other electrical contacts and components. This

incident illustrated the importance of fire extinguishing

practices and the choice and use of fire extinguishing

agents.

Prairie Island Nuclear

Generating Plant,

Unit 1 

August 3, 2001 A fire occurred in a 4,160V nonsafety-related electrical

panel on Unit 1, during initial startup while plant

operators were transferring the plant’s electrical power

from the reserve transformer to the main transformer.

The breaker failure initiated a fire in cubicle 12-4 of bus

12. The failure also actuated the generator transformer

protective relaying scheme, including a lockout of bus

12. The bus lockout opened breaker 12-1 (bus 12 is the

source from the 1RX transformer), and actuated the

protective relaying scheme. The protective relaying

scheme initiated a turbine/reactor trip and actuation of

the auxiliary feedwater system. 
Table H.1-1. Summary of Selected U.S. Commercial Nuclear Power Plant Fire Incidents

Plant Date of Incident Description of Fire Incident

H-5

Fort Calhoun Station,

Unit 1

December 19,

2001

A fire occurred in a corridor between safety injection

pump room 22 and the containment tension stressing

gallery as a result of an overloaded extension cord used

to supply power to a 55-gallon grease drum heater. The

fire ignited ordinary combustible materials in the area.

Room 22 was completely filled with dense smoke in

addition to spreading to adjacent remote areas. The

smoke travel resulted in a deluge system actuating in

the auxiliary building stairwell (water curtain). The

ensuing water sprayed onto safety-related motor control

centers (MCCs), causing shorts on safety-related

circuits. The water curtain was required since there is

no fixed fire barrier between the fire areas. The root

cause of this fire event was determined to be

unauthorized modifications to the male connection of an

extension cord, which resulted in overheating and the

subsequent fire.

McGuire Nuclear

Station, Unit 2

August 23, 2002 A fire occurred from a leak in the hydrogen dryer

associated with the Unit 2 turbine generator. The fire

area was in the Unit 2 turbine building, one level below

the turbine. The automatic sprinkler system activated in

response to the fire alarm. A manual reactor trip was

initiated and Unit 2 experienced an elevated steam

generator water level. The plant fire brigade responded

to the hydrogen dryer fire and isolated the hydrogen

leak.
H-6

H.2 San Onofre Nuclear Generating Station, Unit 1, February 7 and March 12, 1968

Two similar incidents involving self-ignited cable fires took place within a 5-week period. On

February 7, 1968, San Onofre Nuclear Generating Station (SONGS) Unit 1 experienced a selfignited cable fire adjacent to a containment penetration and on March 12, 1968, another self-ignited

cable fire occurred in a 480-volt switchgear room. These fires showed significant fire propagation

beyond the initiating cable. The licensee reported that three horizontal stacked cable trays were

burning at the time that the fire brigade arrived on the scene (several minutes after the apparent

time of ignition).

At 4:45 p.m., on February 7, 1968, the unit was operating at 360 MWe and performing core

depletion tests. All of the pressurizer heaters had been on for 96 hours when the operator noticed

that the heaters were not actually operating. At about the same time, the control room received a

480-volt bus ground alarm, a loud noise was heard in the control room, and the lights flickered.

At 4:47 p.m. a security officer reported a fire at the southeast side of the containment. The reactor

operator transferred the #1 480-volt bus, to the #3 480-volt bus which caused ground indications

on both buses. The reactor operator then transferred the 480-volt buses back to their normal

sources. The #1 480-volt bus ground cleared when the Group C pressurizer heater breaker was

opened. Fire-fighting was initiated immediately, and the fire was very quickly reported to be under

control at 4:47 p.m., (Just 2 minutes after the first signs of the presence of fire). The fire was fought

w 2ith carbon dioxide (CO ) and Ansul portable extinguishers.

At 5:10 p.m., the reactor and turbine (generator) were manually tripped. No spurious equipment

operations were noted during the incident, and there was no apparent effect on the reactor

shutdown/cooldown efforts.

On March 12, 1968, SONGS Unit 1 experienced another cable fire, this time in a cable tray in the

#2 480-volt switchgear room. At the time of the fire incident, the unit was operating at 380 MWe

when, at 12:21 a.m., the control room received several alarms including “Intake Structure Hi Level,”

“480-volt System Ground,” “Station DC Bus Ground or Low Voltage,” and “Hydraulic Stop Gate

Trouble.” These were followed by a “Sphere Heating and Ventilating System Trouble” alarm.

At 12:25 a.m., the annunciator panel for the turbine generator first out, auxiliary, and electrical

boards were lost. An auxiliary operator reported smoke in the #2 480-volt switchgear room. At

12:27 a.m., operators observed blue arcing above the east door window of the #2 480-volt

switchgear room. At 12:32 a.m., fire was observed in three cable trays above east door.

The reactor was tripped at 12:34 a.m., and the operator began unit shutdown actions at 12:37 a.m.

The #2 480-volt was cleared by over current relay operation.

At 12:35 a.m., the licensee requested assistance from the closest outside fire department, which

happened to be a Marine Corps Fire Department. At 12:45 a.m., 24 minutes after the first control

room alarms were received, the fire department arrived on the scene, but the electric motor-driven

fire pumps would not start. Therefore, at 12:56 a.m., the licensee started the gasoline engine

driven backup emergency fire pump. The fire was declared extinguished at 1:00 a.m., 39 minutes

after the initial control room alarms.
H-7

During cooldown efforts following the fire, the licensee determined that the coolant boron

concentration was decreasing instead of increasing as expected. As a result, the cooldown was

suspended for 3 hours and 40 minutes until the problem was diagnosed and fixed.

Post-fire investigation revealed that power and/or control circuits were affected for residual heat

removal (RHR) suction and discharge valves, the component cooling water (CCW) heat exchanger

outlet valve, the south primary makeup water pump, and three annunciator panels. Damaged

cables rendered the following equipment electrically inoperable:

• safety injection recirculation valves

• west recirculation pump and discharge valve

• electric auxiliary feedwater pump

• safety injection train valves [west train motor-operated values (MOVs)]

• refueling water pump discharge valve to recirculation system

The following equipment was lost as a result of the relay cutout of the #2 480-volt bus:

• west RHR pump

• south transfer pump

• boric acid injection pump

• boric acid storage tank heaters and boric acid system heat tracing

• south primary plant makeup pump

• flash tank bypass valve

• east and west flash tank discharge pumps

• center component cooling water pump

• several other MOVs

While the first incident had only a minimal impact on the plant, the second incident rendered a large

number of components. Nevertheless, a sufficient number of components and systems remained

available to allow for orderly shutdown and core cooling. In addition, at least one of the alarms

received in the control room was (namely the Intake Structure Hi Level alarm) apparently spurious.

An operator reporting from the intake structure found no reason for this alarm to have sounded.

In terms of the fire cause, the two incidents shared many similarities. The investigation concluded

that the most probable cause of both fires was thermally and mechanically stressed cables, coupled

with the use of individual fuses to provide for clearing of faults on each phase of the three-phase

340-volt circuits. It also appeared that the cables were undersized for their design current loads

under their actual installation conditions.

The initial fault was thought to be a cable-to-cable, phase-to-phase hot shot involving two separate

power feeds from the same three-phase power bus. The fusing configuration allowed back-feeding

of fault current through the unfaulted phases of each power feed, which led to an even more severe

overcurrent condition for the conductors.
H-8

Both incidents involved self-ignited cable fires. As such, they are important because they were the

earliest fire incidents at a nuclear power plant where self-ignition of cables resulted in extensive

equipment damage and loss of equipment operability. While the first incident resulted in little or no

fire spread, the second incident involved fire spread to three cable trays that were entirely burned

for 4.60 m (15 ft). Investigation of the incidents led to recommendations that urged the industry to

reexamine cable qualification and raise the standards for establishing cable ampacity limits and for

improving the flammability behavior of cables.

In both incidents, the fires did not cause complete loss of core cooling capability, core damage,

radiation release or any injury to plant personnel or the public. The available sources do not offer

detailed discussion of fire-fighting activities, occurrence of hot shorts (other than the initial cable-tocable fault that initiated the second incident), the nature of the other circuit failures or operator

actions in response to the failures, caused by the fire.

Reference

San Onofre Nuclear Generating Station Unit 1, Report on Cable Failures—1968, Southern

California Edison Company, San Diego Gas & Electric Company, Publication date unknown, but

circa 1968.

H.3 Browns Ferry Nuclear Power Plant, Unit 1, March 22, 1975

At noon on March 22, 1975, both Units 1 and 2 at the Browns Ferry Nuclear Power Plant (BFNP)

were operating at full power, delivering 2,200 megawatts of electricity to the Tennessee Valley

Authority (TVA).

The BFNP consists of three boiling-water reactors (BWRs). Units 1 and 2 share a common cable

spreading room (CSR) located beneath the control room (CR). Cables carrying electrical signals

between the CR and various pieces of equipment in the plant pass through the CSR. Just below

the plant’s control room, two electricians were trying to seal air leaks in the CSR, where the

electrical cables that control the two reactors are separated and routed through different tunnels

to the reactor buildings. There were using strips of spongy foam rubber to seal the leaks. They

were also using candles to determine whether or not leaks had been successfully plugged by

observing how the flame was affected by escaping air. One of the electricians put the candle too

close to the foam rubber, and it burst into flame.

Following ignition of the polyurethane (PU) foam in the Unit 1 CSR, the fire propagated through the

penetration in the wall between the CSR and the Unit 1 reactor building. After the insulation burned

off, the electrical cables shorted together and grounded to either their supporting trays or the

conduits. In addition to the direct fire damage, the fire deposited an extensive amount of soot on

all equipment located in the reactor building below the refueling floor. More than 600 of the burned

cables contained circuits for the safe shutdown of one or both of the operating reactors. The direct

fire loss was $10 million, and the cost of fossil fuel used to produce the replacement electricity over

the next 18 months was $200 million.
H-9

Approximately 15 minutes passed between the time the fire started (12:20 p.m.) and the time at

which a fire alarm was turned in. One of the electricians told a plant guard inside the turbine

building that a fire had broken out, but confusion over the correct telephone number caused a delay

in sounding the fire alarm.

This fire burned a large number of cables associated with penetrations between the CSR and the

reactor building. The fire initiated in the CSR and initially involved the readily combustible and

exposed PU foam of an incomplete cable penetration seal. The fire immediately propagated

through a gap in the penetration seal into the adjacent reactor building. This spread was enhanced

by air flow through the penetration seal gap, caused by the negative pressure in the reactor

building. In this case, the penetration seal was not complete (i.e., the seal was still under

construction and lacked noncombustible cover panels).

The fire at BFNP demonstrates that, given a sufficient initial source of readily combustible fuel (the

PU foam in this case) in close proximity to a large concentration of cables in open cable trays, a

self-sustaining and propagating cable fire may result. In this case, fire propagated both horizontally

and vertically, thereby igniting and damaging cables. Cables inside conduits running near the

burning cable trays were also damaged.

The fire in the Browns Ferry CSR was controlled and extinguished without the use of water. The

fire in the reactor building was unsuccessfully fought for several hours with portable carbon dioxide

2

(CO ) and dry chemical extinguishers; however, once water was used, the fire was extinguished

2

in a few minutes. After actuation of the CSR CO fire suppression system, openings between the

CR 2 and the CSR had to be plugged to stop the entry of smoke and CO into the CR. Some of these

openings were in the floor of the CR at the points where the cables entered the CR. This appears

2

to violate the design provision that these cable entryways would be sealed. Actuation of the CO

system in the CSR made the situation worse, driving the smoke and toxic fumes into the CR, which

became uninhabitable.

The BFNP design incorporated provisions for sealing the openings between major structural

divisions, such as the reactor building, the CSR and the control room. However, in the case of the

Browns Ferry fire, one such seal between the CSR and the reactor building was ineffective in

limiting the spread of the fire and was ultimately the primary cause of the fire. The lack of other

seals, such as those between the CSR and the CR, impeded plant operation during the fire.

Notably, the smoke detectors in the Browns Ferry CSR did not alarm, despite presence of smoke

possibly because the normal flow of air from the CSR to the reactor building drew the smoke away

from the installed detector in the CSR. The smoke also penetrated the control room (through the

unsealed cable entryways), but the fire detectors installed in the control room were of the ionization

type and did not detect the combustion products generated by the cable fire and did not alarm. The

reactor building also had a great deal of smoke in the vicinity of the fire, but the licensee had not

installed detectors in that area.
H-10

A principal lesson learned from the BFNP fire is the failure of fire prevention. The Review Group

(NUREG-0050) recommended that the licensees review the ventilation systems in all operating

NPPs and upgrade them, as appropriate, to ensure their continued functioning if needed during a

fire. The Review Group further recommended that the licensees should provide the capability to

control ventilation systems to deal with fire and smoke, but such provisions must be compatible with

requirements for the containment of radioactivity. Licensees should also protect the CR from both

radioactivity and smoke or toxic gases. Adequate breathing apparati and recharging equipment

should be available for operators, fire-fighters, and damage control crews who may be required to

work simultaneously during a prolonged incident.

The Review Group concluded that more comprehensive regulatory guidance was needed to provide

fire protection design criteria to implement the requirements of General Design Criterion (GDC) 3

as specified by Appendix A to Title 10, Part 50, of the Code of Federal Regulations (10 CFR

Part 50). The Browns Ferry fire and its aftermath revealed some significant inadequacies in design

and procedures related to fire at the plant, including gaps in the defense against fires.

References

BL-75-04, “Cable Fire at Browns Ferry Nuclear Power Station,” U.S. Nuclear Regulatory

Commission, March 24, 1975.

BL-75-04A, “Cable Fire at Browns Ferry Nuclear Power Station,” U.S. Nuclear Regulatory

Commission, April 3, 1975.

BL-75-04B, “Cable Fire at Browns Ferry Nuclear Power Station,” U.S. Nuclear Regulatory

Commission, November 3, 1975.

“Browns Ferry Nuclear Power Plant Fire,” Hearings Before the Joint Committee on Atomic Energy,

94 Congress of the United States, September 1997. th

Hunter, L.W., “Fire Hazards of Electric Cables in Nuclear Power Plants,” John Hopkins APL

Technical Digest, Volume 4, No. 3, pp. 205–211, 1983.

Murphy, C.E., Office of Inspection and Enforcement, Region II, Regulatory Investigation Report:

Subject: Tennessee Valley Authority, Browns Ferry Units 1 and 2, Docket Nos. 50-259/75-1 and

50-260/75-1, “Fire in Cable Spreading Room and Reactor Building on March 22, 1975,” July 25,

1975.

Nuclear Regulatory Commission (U.S.), NUREG-0050, “Recommendations Related to Browns

Ferry Fire,” Report by Special Review Group, NRC, Washington, DC, February 1976.

Ramsey, C.B. and M. Modarres, Commercial Nuclear Power Assurance Safety for the Future,

John Wiley & Sons, Inc., New York, 1997.

Scott, R.L., “Browns Ferry Nuclear Power Plant Fire on March 22, 1975,” Nuclear Safety, Volume 1,

No. 5: September–October 1976.
H-11

H.4 North Anna Power Station, Unit 2, July 3, 1981

On July 3, 1981, North Anna Unit 2 was at a power level of 17.9-percent when an internal fault in

one phase of main transformer B led to a catastrophic transformer failure and fire. Ceramic

insulation shifted, the side of the transformer ruptured, and transformer oil sprayed from the

opening over the transformer and the outside wall of the turbine building.

The fire caused the feeder breakers from a reserve station service transformer to two station

service buses to trip open. The voltage transient caused by this event led to several bi-stables in

the solid-state protection system to drop out, resulting in a high steam line flow signal. Since the

reactor coolant temperature was low, this led to a safety injection signal.

The fire brigade was activated immediately, and the licensee also contacted the local fire

department for assistance. The deluge systems on transformers B and C activated. However, the

fire was too severe for the capability of the system and the fire continued to burn. It took the fire

brigades about 1 hour to bring the fire under control.

Although this incident is considered a severe fire in classical fire protection terms, it affected only

nonsafety components. Despite the low potential risk impact, the incident provided an interesting

insight about fixed fire suppression system capabilities. Specifically, the incident demonstrated that

a fixed fire suppression system can be overwhelmed even when the fire initiates in those

components that the system is intended to protect. In other words, it showed that the effectiveness

of the suppression system may be an important factor.

Reference

Licensee Event Report (LER) 339-81-055, North Anna Power Station, Unit 2, Docket No. 50–339,

Virginia Electric and Power Company, July 15, 1981.
H-12

H.5 Rancho Seco, March 19, 1984

On March 19, 1984, Rancho Seco was operating at 85-percent power, and had been experiencing

problems with the automatic level control of the de-foaming tank and hydrogen side drain regulator

tank of the main generator. The licensee switched the drain regulator tank level to manual mode,

requiring direct operator level control. However, operators apparently failed to pay adequate

attention to the level control and this allowed the main generator seal oil pressure to decrease.

This, in turn, allowed hydrogen to escape from the generator. At 9:50 p.m., hydrogen gas exploded

and started a fire.

Plant personnel in the area immediately detected the fire, and it was extinguished by the fixed

automat 2ic carbon dioxide (CO ) system within 14 minutes. Nonetheless, the fire caused significant

damage in a relatively short frame, primarily because of the initial explosion and early burning.

This fire is one of few turbine building fire incidents in the United States that has caused significant

damage. The incident demonstrated the unique nature of the turbine building fire hazards, which

in this case, included a hydrogen gas leak and explosion and the potential for fast-developing fires

that may cause damage despite effective operation of the fire suppression systems. This incident

also demonstrated that turbine building analyses may warrant attention to more severe fires than

might reasonably be postulated in other plant areas. This particular incident apparently had a

minimal impact on plant operations and safety systems, but the impact on operators is a plant

specific-factor, consistent with the presence (or absence) of safety-significant equipment in the

turbine building.
H-13

H.6 Waterford Steam Electric Station, Unit 3, June 26, 1985

On June 26, 1985, the plant was operating at power when a fire occurred in one of the main

feedwater pumps. An electrician notified the control room that smoke was emanating from main

feedwater pump A, and an operator dispatched to the scene reported back to the control room that

the pump was on fire. Control room (CR) operators tripped the cited pump, began reducing reactor

power, and declared that an unusual event was underway.

Five minutes after the initial report of a fire, the operator notified the CR that the fire was actually

in main feedwater pump B, rather than A as previously reported. As a result, the CR operators

immediately tripped the turbine, which, in turn, caused the reactor to trip. Since both main

feedwater pumps were secured, the steam generator level dropped below the emergency feedwater

system setpoint.

The licensee activated the fire brigade upon confirmation of the fire. The fire brigade used a local

hose station and water streams to fight the fire and managed to extinguish it in about 10 minutes.

The fire was limited to a small portion of the outer wrapping of insulation on the feedwater piping

and was attributed to design and fabrication errors.

In most senses, this fire was relatively small and, overall, presented a relatively minor challenge to

nuclear safety (a reactor trip with all safety systems available). The interesting aspect of this

incident is that operator/personnel error led to an initial report identifying the wrong pump as the

one on fire. As a result, the operator initially tripped the unaffected pump, and ultimately was forced

to trip both main feedwater pumps. Although this incident involved only nonsafety-related trains,

it provided an interesting insight into the possibility of an indirect impact of fire on multiple train

availability. That is, for various reasons, a fire may lead to unaffected trains being taken out of

service. In this case, the cause was operator error and the operator’s actions were classified as

an error of commission. This is, rather than failing to take a desirable action, the operator in this

case took an action that was undesirable.
H-14

H.7 Fort St. Vrain Nuclear Generating Station, October 2, 1987

Fort St. Vrain is a single-unit high-temperature gas-cooled reactor (HTGR), which (like other

HTGRs) reactor uses graphite as a moderator and helium gas for heat removal from the core. Fort

St. Vrain had two main cooling (helium) loops. After passing through the core, the helium flowed

through the two steam generators (one per cooling loop). Two steam-driven circulators for each

loop provided motive power for the helium. The steam for the circulators comes from the discharge

of the high-pressure turbine of the turbine-generator. The steam then passes through the steam

generators once more for superheating before being taken to the intermediate and low-pressure

turbines.

On October 2, 1987, the plant was coming out of a long outage and was in the midst of its initial

power ascension. As part of this process, the operators closed a hydraulic valve in the turbine

building, when they noticed a drop in hydraulic oil pressure. An inquiry into the causes of this drop

revealed that a filter bowl (canister) had failed and high-pressure oil (about 3,000 psig) was

spraying (close to a 15-ft distance) onto hot exposed steel. The petroleum-based hydraulic oil

ignited, starting the fire, because the temperature of the hot surfaces was above the auto-ignition

point of the oil. The equipment operator who discovered the fire initially succeeded in extinguishing

it using a portable dry-chemical extinguisher. However, since he did not close the valve feeding

the failed filter, the oil continued to spray and re-flashed (re-ignited). By this time, the fire was

relatively large (estimated at 8 ft x 3 ft).

The licensee immediately activated the plant’s fire brigade was asked an outside fire department

to respond. The licensee also dispatched a reactor operator to the reactor building to close the two

control valves for the hydraulic system to cut off the supply of oil to the failed filter. That operator

managed to close one of the two valves immediately. However, the handle for the other valve was

missing and, therefore, some delay occurred in cutting off the oil from the fire. As soon as the oil

was cut off, the fire was extinguished and the operators managed to close off and isolate the failed

filter and activate the available hydraulic system train.

The damage caused by this fire was limited to the immediate area of the fire at the north end of the

turbine building. The fire also damaged several cables that had some effect on the control room

(CR). In addition, the fire affected valves, instruments, and structural elements. However, the fire

had only a minor impact on the plant shutdown and reactor cooling capabilities.

The fire also had some impact on CR habitability. Apparently, the burning oil and cables generated

large quantities of smoke that hampered the initial fire-fighting efforts. The cables damaged by the

fire also caused the CR ventilation system to shift to radiation emergency mode, and caused a loss

of electric power at the fire location, thereby rendering the electric motor-driven smoke ejectors

useless. In this mode, the system shifted to suction from the turbine building, thereby drawing

some smoke into the CR. Within 2 minutes of the shift in ventilation systems, the ventilation system

switched to the purge mode. However, smoke continued to enter the CR because positive pressure

in the room could not be maintained as a result of frequent use of the door between the CR and the

turbine building. Ultimately, the operators had to prop open the door separating the control room

and Building 10 to allow fresh air to be drawn into the CR.
H-15

Reference

“Preliminary Report on the Impact of the FSV October 2 Fire,” Fort St. Vrain Nuclear Generating nd

Station, Public Service Company of Colorado, October 30, 1987.

H.8 Oconee Nuclear Station, Unit 1, January 3, 1989

On January 3, 1989, Oconee Unit 1, was being brought up to power following a trip that had

occurred a few days earlier. The unit had reached 26-percent power at 7:16 p.m., when the 6.9 kV

switchgear (1TA) failed explosively and caught fire. Subsequent investigation could not establish

the precise cause of this incident.

As a result of the switchgear failure, the main turbine and two reactor coolant pumps tripped,

thereby initiating a reactor transient. The operators immediately began to reduce reactor power.

The average reactor temperature was 302 °C (575 °F) at the beginning of the incident, and core

cooling was initially maintained by the two operating reactor coolant pumps (RCPs) and main

feedwater flow through the steam generators (S/Gs). The operators also started two high-pressure

injection pumps to compensate for contraction of the water in the main coolant loop as it was

cooling down in response to the power reduction. When the power dropped to 4-percent, the

operators tripped the reactor.

Meanwhile, the control room (CR) received fire alarms and activated the fire brigade to respond to

the fire. Later, the licensee called off-duty shift personnel to assist in the fire- fighting effort. The

2

fire brigade made two initial attempts to suppress the fire using carbon dioxide (CO ) and dry

chemical fire extinguishers, but failed extinguish the fire. CR operators deenergized the DC power

bus in order to isolate the impacted 1TA switchgear from all electrical sources. The fire brigade

then decided to apply water to the fire using a fog nozzle. To further protect the fire-fighters, the

operators also deenergized the other train of the nonsafety related 6.9 kV switchgear (i.e., 1TB),

which was located near 1TA. The fire brigade used the water fog on the fire and at 8:15 p.m., about

1 hour after the switchgear failure, the fire brigade declared the fire as being completely

extinguished.

Tripping of switchgear 1TB (to protect the fire fighters) caused the remaining reactor coolant pumps

to trip. Under these conditions, the integrated control system (ICS) is designed to raise the water

level in the S/G to 50-percent and swap the feedwater nozzles from main to auxiliary. However,

because of fire damage to the signal cables, the ICS failed and the operators had to manually

execute these two actions. In doing so, however, the operators forgot to close the main feedwater

valve. This further accelerated the rapid cooldown process that was already underway.

Furthermore, since the operators focused on in-core thermocouple readings to monitor reactor

temperature, they did not properly monitor the rate of cooldown at different points of the main

coolant loop. As a result cold leg temperature dropped to about 219 °C (426 °F) in about 1 hour.

The shift engineer and shift supervisor determined that the temperature in parts of the reactor may

have dropped faster than 38 °C (100 °F) in that hour, which means that the plant may actually have

entered the thermal shock operation region (overcooling).
H-16

Because operators had started the high-pressure injection system, reactor pressure reached 2,355

psig for a short time. Later, the pressure reached 2,385 psig, also for a short time. Operations then

stopped the high-pressure pumps to control the high-pressure condition. These two pressure

spikes, combined with the possibility of operating in the thermal shock operation region, could have

endangered the integrity of the main vessel if the conditions had persisted for an extended time.

At some point in the incident, smoke did find its way into the main control room. The available

literature does not describe either the extent of the smoke or the path by which the smoke found

its way into the CR. Consequently, it is not clear whether the smoke had any impact on operator

performance, although one report cites the smoke (rather in passing) as a contributing factor to the

error that led to the overcooling transient.

Reference

Licensee Event Report (LER) 26989002, “Fire in 1TA Switchgear Due to Unknown Cause,” Oconee

Nuclear Station, Unit 1, Event Date January 3, 1989.

H.9 H.B. Robinson Steam Electric Plant, Unit 2, January 7, 1989

At the time of this incident on January 7, 1989, Robinson Unit 2, was in a refueling outage. At

10:30 p.m., as part of an air test of the main generator, a maintenance crew erroneously connected

the instrument air header to the main generator hydrogen manifold using a rubber hose. This

allowed the bulk hydrogen supply, which is at 120 psig, to be directly connected to the station’s 95

psig compressed air system. The configuration was such that hydrogen flow to the generator was

blocked, but flow into the station air system was not. Hence, hydrogen spread into the plant’s

general purpose compressed air system.

At the time the maintenance crew established the hose connection, the station air compressor was

out of service and the station air system was connected to the instrument air system. The station

air system was in greater demand because plant personnel were using air-driven tools throughout

the plant. This caused the majority of the hydrogen to migrate into the station air system.

Approximately 1 hour after the maintenance crew established the connection, the crew noticed that

generator pressure had not increased. At approximately the same time a small fire was discovered

in an air junction box on the turbine deck inside the turbine building, the fire quickly extinguished

and did not notice any damage. However, approximately 3 hours after the maintenance crew

established the connection, a contract worker reported that flames were coming out of his air

operated-grinder. Upon this discovery, the licensee ceased all work that could cause a spark and

prohibited the use of the air system.

The licensee then took samples of the air at several locations and discovered that the hydrogen

concentration ranged from 50-percent to 150-percent of lower explosive limit (LEL). The hydrogen

had also migrated into the entire system, which encompassed practically all plant locations

including the auxiliary building and the containment. No further fires occurred, and the licensee

eventually purged the system of hydrogen.
H-17

This incident is of interest because it illustrates the somewhat unique point, that unexpected fire

sources can arise during a refueling outage. In this case, at least two minor fires occurred, and

there was clearly an inherent potential for more, and perhaps more serious, fires.

Reference

Licensee Event Report 26189001, “Hydrogen Introduced Into the Instrument Air System,” H.B.

Robinson Steam Electric Plant, Unit 2, Event Date January 7, 1989.

H.10 Calvert Cliffs Nuclear Power Plant, Unit 2, March 1, 1989

On March 1, 1989, Calvert Cliffs Unit 2 was operating at 100-percent power. At 4:45 p.m., a fire

was discovered in a control panel in the main control room (MCR). At the time, an operator was

in the process of verifying a repair on the over-speed trip mechanism of the auxiliary feedwater

pump trip/throttle valve actuator. As part of this procedure, the operator put the hand switch for the

valve in the shut position. The shut position indicating light flickered, and the operator heard a

buzzing noise on the control panel. The operator repeated the action with the same result. The

operator opened the panel cover and discovered a fire at the hand switch. Using a hand-held

Halon fire extinguisher, the operator extinguished the fire in 1–2 minutes. In the meanwhile, a 10-

amp fuse in the associated circuit blew. However, because the fire was extinguished quickly, the

control room supervisor did not call the fire brigade.

When the operator discovered the fire, a turbine building operator was called to reset the throttle

valve. In the attempt to reset the valve, that operator discovered that a solenoid associated with

the valve was smoking, but there were no visible flames. The solenoid stopped smoking,

apparently when the 10-amp fuse blew. The fire in the MCR panel caused some damage to

nearby wires, but the licensee did not notice any other damage resulting from this incident.

Moreover, this incident did not cause a significant safety hazard and its impact was limited to an

isolated part of a safety-related system. The lack of damage can be attributed, at least in part, to

the immediate response of the operator whose actions led to the initiation of the fire.

This incident is one of only a very few incidents in U.S. commercial NPPs that lend insight into

multiple fire ignitions in a single incident. In this case, a small fire occurred in the MCR and an

incipient fire (the smoking solenoid) occurred in the auxiliary feedwater pump room; the common

link between the fires was a common electrical circuit.

Reference

Licensee Event Report 31889004, “Auxiliary Feedwater Pump Trip Circuitry Fire in Control Room

Due to Maintenance Error,” Calvert Cliffs Nuclear Power Plant, Unit 2, Event Date March 1, 1989.
H-18

H.11 Shearon Harris Nuclear Power Plant, October 9, 1989

On October 9, 1989, the Shearon Harris plant was operating at full power. At 11:05 p.m., a turbine

generator and main power transformer differential relay tripped and started a chain of events that

led to fires at three locations involving one main transformer and the main generator. As a result

of the relay trip, the main generator output breaker also tripped. This, in turn, caused a turbine trip

and a reactor trip. The auxiliary feedwater system actuated as designed, but the turbine-driven

pump failed to operate properly so operators switched to motor-driven auxiliary feedwater pumps.

The operators closed the main steam isolation valves to limit the cooldown rate.

The initial cause of the event was multiple ground faults in a bus duct near main power transformer B.

The licensee event report (LER) stated that the ground faults apparently resulted from aluminum

debris carried into the duct by the forced air ventilation system used to cool the bus duct. The

licensee suspected that the debris entered the ventilation system as a result of two damper failures,

one of which occurred on February 27, 1988, and a second one during the summer of 1989. The

ground fault caused arcing over a 50-foot length of the bus, thereby reducing the dielectric strength

of the air. In accordance with the air, per the design of the system, the air then entered the bushing

box of the transformer, causing ground faults in the bushing box and leading to a crack in the lowvoltage bushings. The bushing crack, in turn, led to a spill of oil and ignition of the first fire at the

transformer.

The fault in the main transformer bushing box and bus duct A caused the voltage of the generator

neutral to become elevated. A current transformer was mounted around the neutral conductor, from

which it was isolated by insulating tape. However, the insulation resistance of the tape was

apparently insufficient to withstand the elevated neutral voltage and an electrical breakdown

occurred, causing the neutral conductor to short to ground. The arcing caused by this short burned

holes in generator-related piping, which, in turn, subsequently allowed the housing above the

hydrogen fire to ignite (the third fire).

At 11:09 p.m., the control room (CR) was notified of a fire at main power transformer B, and an oil

fire on the second level of the turbine deck underneath the main generator. The licensee

immediately activated its onsite fire brigade who also noted a hydrogen fire on the second level of

the turbine deck underneath the main generator (second fire). The deluge system at the main

transformer activated as designed.

The licensee also contacted offsite fire departments shortly after the initiation of the incident to

assist in the fire-fighting efforts. Later, the licensee created the prompt notification of offsite fire

departments as having limited the damage caused by the fires.

As previously noted, the auxiliary feedwater system automatically actuated in response to the

incident. However, the turbine-driven auxiliary feedwater pump tripped shortly after it started. The

licensee later identified the cause of the trip a spurious over-speed trip signal from the tachometer.

No link between the failure of the auxiliary feedwater pump and the fire has been established, and

this appears to have been an independent (random) failure event.
H-19

At 11:35 p.m., an alert was declared and activated the technical support center (TSC).

By 12:13 a.m. on October 10 (a little more than over 1 hour after initiation of the event), the oil fire

at the generator hosing was extinguished. Also, the fire at the main power transformer was

believed to be under control by the deluge system. The hydrogen fire underneath the generator

was also considered to be under control.

By 01:45 a.m., a small residual oil fire at the main transformer was extinguished using a portable

dry chemical extinguisher. By 02:45 a.m., (2 hours and 40 minutes after incident initiation) the

licensee completed walkdowns to verify that all three fires were extinguished, fire watches were

po 2sted at the fire locations, and purged the main generator CO .

The fires in this incident were of relatively long duration, lasting about 1 hour and 45 minutes total,

and were relatively severe from a classical fire protection perspective. However, from a nuclear

safety perspective, the fires had a relatively modest overall impact. The plant did trip automatically

and an auxiliary feedwater pump did fail (apparently a random failure). However, the operators

responded appropriately to the situation and properly controlled the plant shutdown including proper

control of the cooldown rate.

The incident is of interest because it is one of the few incidents in the United States that involved

multiple fires occurring concurrently. As such, the incident demonstrated that multiple fires may

occur simultaneously in different areas of a plant. As seen in other such incidents, one of the

common links was a common electrical system. However, the secondary hydrogen fire was

apparently the result of damage caused by the failure of the current sensor on the generator neutral

cable, so there were multiple contributing factors rather than simply a common electrical system

that became overloaded.

Reference

Licensee Event Report # 40089017, “Electric Fault on Main Generator Output Bus Causing Plant

Trip and Fire Damage in Turbine Building,” Shearon Harris Nuclear Power Plant, Event Date

October9, 1989.
H-20

H.12 Salem Generating Station Unit 2, November 9, 1991

On November 9, 1991, Salem Unit 2, was operating at full power when a reactor trip occurred,

causing the main generator breaker to open. The auto stop oil system was in test mode and, as

result, the turbine valves cycled open while the generator was disconnected from the grid (i.e., the

turbine re-started without an appropriate generator load on the system). An over-speed condition

occurred, but the over-speed protection system failed to function properly and allowed the turbine’s

rotational speed to exceed 2,500 rpm compared to the normal operating speed of 1,800 rpm. The

forces associated with this level of over-speed caused the blades to break apart, ejecting fragments

from the turbine casing. Hydrogen gas escaped and caught fire because of a seal failure caused

by the excessive vibration. The vibration also severed the lube oil pipes causing a release of the

oil that also caught fire.

The following automatic fire suppression systems actuated promptly as designed:

• deluge system protecting the inboard generator bearing housing

• deluge system protecting the low-pressure bearing housing

2

• low pressure CO system protecting the main generator exciter

• wet pipe sprinkler system below the main generator pedestal

The entire sequence of events leading to turbine failure lasted 74 seconds. Fires had already

occurred by that time and some of the automatic suppression systems had activated. The

automatic suppression systems managed to extinguish some of the fires.

By coincidence the fire brigade happened to be outside the protected area at the time of fire. With

the assistance of plant security, the brigade promptly re-entered the plant proper and managed to

be on the scene in full gear within 5 minutes of fire ignition. With the help of plant fire brigade

personnel, the fire was contained rapidly and extinguished within 15 minutes. The fire caused

relatively little damage compared to that done by the ejected blades.

The licensee subsequently determined that the fire impacted the turbine and exciter ends of the

main generator. Because the main turbine generator of Salem Unit 2 is not enclosed, the hydrogen

and smoke from the fire escaped directly into the atmosphere. As a result, the fire brigade did not

need to be concerned with hydrogen pocketing under the structural elements of the ceiling.

This incident is considered important because despite the potential for a very severe fire, the

licensee observed only very limited fire damage. In this case, catastrophic failure of a turbine led

to a fire. This event is somewhat unique in that the fire suppression system was adequate to

control the ensuing fire and, coupled with the response of the fire brigade, was to extinguish the fire

very quickly. Some localized fire damage resulted, and the costs of replacing the failed turbine

were extensive, but the fire had no impact on the safety-related elements of the plant.

Another notable aspect of this incident is that a failure related to a main turbine generator system

led to turbine disintegration, which, in turn, caused the fire. It is also interesting to note that two

independent events contributed directly to the initiation of the fires. First, the auto-stop oil system

was in test mode and this created a condition where the turbine was, in effect, re-started without

an appropriate load and this, in turn, led directly to the potential for an over-speed condition to

occur. Second, the over-speed protection system failed to function, allowing the over-speed

condition to progress unchecked.
H-21

Reference

Licensee Event Report 31191017, “Reactor/Turbine Trip on Low Auto-Stop Oil Pressure Followed

by Turbine/Generator Failure,” Salem Generating Station Unit 2, Event Date November 9, 1991.

H.13 Waterford Steam Electric Station Unit 3, June 10, 1995

On June 10, 1995, Waterford Unit 3 was operating at 100-percent power. At 8:58 a.m., failure of

a lightning arrester on a substation transformer (230 kV/34.5 kV) caused a severe electrical

transient that, in combination with the failure of a breaker, led to failure of non-vital switchgear 2A

and fire in the breaker cubicle for the startup transformer. This led to a reactor trip and a series of

other nonsafety-related equipment trips, signal actuations, and equipment activations.

All 36 fire detectors for the turbine building switchgear room alarmed to the control room (CR)

indicating panel. However, the CR operators did not become aware of the fire detector alarms

because other plant alarms were sounding at the same time, the fire protection alarm board was

in an area not readily visible to the operators, and the fire detector alarm panel buzzer had been

covered with tape. Hence, CR operators remained unaware of the fact that a fire had started in the

switchgear room.

At 9:06 a.m., the control room received a report from an auxiliary operator, who happened to be a

trained fire brigade member, that heavy smoke was coming out of the switchgear room. The shift

supervisor asked if the auxiliary operator could observe flames or an orange glow. The auxiliary

operator responded that he could not see flames but a large amount of smoke was coming out of

the switchgear room. The shift supervisor instructed the auxiliary operator to confirm the presence

of an actual fire and report back.

Two auxiliary operators donned self-contained breathing apparatus (SCBA) and entered the

switchgear room to verify the presence of a fire and subsequently notified the CR that a fire was

indeed in progress. The exchange of information took place about 30 minutes after the first fire

alarm sounded in the CR (i.e., approximately 9:30 a.m.). At that time the shift supervisor,

announced the presence of fire and activated the fire brigade.

The fire brigade arrived on the scene and initially attempted to extinguish the fire using hand-held

2

fire extinguishers charged with carbon dioxide (CO ), Halon, and dry chemical agents. However,

all of their attempts proved ineffective. According to the plant procedures, the shift supervisor, then

assumed the leadership of the fire brigade and left the CR for the fire location.

The shift supervisor summoned the local offsite fire department was summoned at 9:41 a.m., and

they arrived at about 9:58 a.m. (17 minutes later). Upon arrival, the offsite fire department

recommended the use of water. However, the shift supervisor, in consultation with other members

of plant operations team, decided to continue using non-water suppression media. The shift

supervisor ultimately gave permission to use water about 90 minutes after the initiation of the fire

(i.e., about 10:30 a.m.). The fire fighters brought the fire under control within 4 minutes after initial

application of water and declared the extinguished about 21⁄2 hours after initiation.
H-22

As noted, the fire was initiated as result of a failure of a switchgear breaker cubicle. The fire

propagated out of the top of the cubicle and ignited vertical cable tray risers above the cubicle.

(One can infer that the switchgear cubicle fire broke through the steel top of the panel and

propagated to those cables. However, it is impossible to determine whether this was attributable

to heat damage to the top panel or whether the top panel may have been damaged in the initial

electrical fault.) In its progression, the fire jumped over a fire stop installed in the vertical section

of the cable tray and continued to propagate. As a result, the fire damaged cables in a 5-foot

diameter column up to a height of about 10 feet above the panel top, and the associated heat

damaged the fire detectors immediately above the fire zone.

The fire eventually reached a horizontal cable tray about 17 feet above the floor (10 feet above the

top of the panel). The fire then propagated horizontally until it came to a fire stop installed in the

horizontal cable tray about 8 feet from the junction with the vertical trays. From the available

information, one can infer that, for the horizontal segment of the cable trays, the flames were of

limited height and/or limited duration. This is because the 6.9-kV power cables that were located

a few inches above the burning 4.16-kV cables were not ignited and had only minor surface

damage after the fire.

The fire also severely damaged two adjacent switchgear cubicles, but four other nearby cubicles

experienced exterior damage only. The investigators postulated that the radiative heat reflected

from the shield wall separating the two switchgear trains caused the exterior damage to those four

cubicles. The fire did not damage any of the redundant train cubicles (on the opposite side of the

shield wall).

It is also interesting to note that the plant’s log records indicated erratic behavior of the A2 unit

auxiliary transformer breaker that was involved in the fire. Operators also noted a few other erratic

indications on the control board during the course of the incident. The records indicated that the

transformer breaker first showed closed and then open. One can infer from this that breaker control

circuit faults led to inaccurate indications on the sequence of events log.

The non-vital switchgear fire at Waterford Unit 3 had little impact on safety-related functions.

Switchgear fires are considered one of the most likely fire scenario in a nuclear power plant.

This incident provides an interesting account of what can happen to the switchgear cubicles and

the cables above it in the event of a switchgear fault and fire. In this case, three cubicles suffered

extensive damage, and four experienced minor damage. Further, the fire propagated through the

steel panel top into a vertical cable tray, about 10-ft up the vertical tray to a crossing horizontal tray,

and about 8-ft along the intersecting horizontal tray before being stopped by a raceway fire barrier.

The potential for fires inside closed electrical panels to propagate outside of the panel has been a

point of significant recent debate. This incident clearly illustrates that this potential exists under

some conditions.

A second factor of interest is the fact that fire fighting was considerably delayed in this incident.

The delay was caused by three nominally unrelated factors, two of which related to decisions made

by plant personnel during the incident.
H-23

One of these three factors was the decision made by the shift supervisor, who insisted on direct

observation of flames before declaring a fire and activating the fire brigade. It took close to 30

minutes an hour (from time of ignition) for two operators to don protective breathing apparatus,

enter the room, verify the presence of flames, seek out the source of the fire, retreat from the room

and report back to the CR.

The second factor related to the strategy used to fight the fire. Once the fire was declared and the

fire brigade arrived on-scene, the fire brigade resisted using water on an electrical fire until multiple

attempts to extinguish the fire using portable extinguishers proved ineffective. As a result, the fire

was allowed to burn far longer and observed damage was perhaps made worse than if prompt and

effective fire suppression had been undertaken. The licensee did not report the reason for the

2

failure of CO , Halon, and dry chemical agent to control the fire.

The final factor contributing to the delay in declaring a fire emergency is the position of the fire

protection annunciator panel and the suppressed sound of the alarm. The panel was not readily

visible to the operators in the CR must have diverted attention from the fire panel. It is important

to note that even after receiving a verbal report of smoke in the switchgear room, the operators did

not approach the fire protection panel to verify the condition of the fire detectors.

Another point of interest in this incident is the fact that operators noted a few erratic indications on

the control board during the course of the incident. This indicates that control circuits can fail

erratically under fire conditions. The licensee did not report the exact reasons for the observed

behavior.

This incident also demonstrated that a fire stop in a horizontal cable tray can be effective in

stopping the progression of the fire. In this case, the fire propagation in the horizontal tray ended

at a raceway fire stop; however, a fire stop in a vertical cable tray may be ineffective. In this case

the fire in the riser jumped past a fire stop and continued to propagate. It is not clear whether the

fire stop delayed propagation.

References

Inspection Report 50-282/95-15, “NRC Augmented Inspection of Waterford 3,” U.S. Nuclear

Regulatory Commission, July 7, 1995.

Information Notice 95-33, “Switchgear Fire and Partial Loss of Offsite Power at Waterford

Generating Station, Unit 3,” U.S. Nuclear Regulatory Commission, August 23, 1995.
H-24

H.14 Palo Verde Nuclear Generating Station Unit 2, April 4, 1996

On April 4, 1996, Palo Verde Unit 2 was in a refueling outage. At 5:00 a.m., a fire watch detected

smoke in the back panel area of the control room (CR), emanating from the Train B emergency

lighting uninterruptible power supply (UPS) panel. At about the same time, an auxiliary operator

discovered smoke and fire in the Train B DC equipment room at the 100-ft elevation of the auxiliary

building. This second fire was discovered on the 480/120-volt essential lighting isolation

transformer. However, multiple trouble alarms on the fire detectors masked the actual fire alarm

coming from this equipment room such that operators did not notice the valid fire alarm signal.

The fires led to the loss of power to the Train B CR emergency lighting circuits, some of general

plant essential lighting, and plant fire detection and alarm system panels. The circuit breaker

supplying power to the UPS panel tripped open when cables in the conduit supplying the power

supply panel overheated causing various conductors to short-circuit. The circuit breaker trip also

deenergized power to the fire detection and alarm panels in the auxiliary building. The fire alarm

annunciator monitor (a computer screen) indicated a large number of fire detector trouble alarms

and these multiple alarms were scrolling on the monitor. This was attributed to the deenergized

fire detection and alarm panels.

The fire in the equipment room was reported by the auxiliary operator to the CR and the shift

supervisor activated the onsite fire brigade. The onsite fire brigade attacked the fire immediately

and extinguished it in a short time. It is not entirely clear whether the fire brigade also reported to

the CR or not. The operators approximately handled the fire in the CR and the CR fire was also

quickly extinguished. The damaged caused by these fires was limited to the components of origin.

That is, neither fire propagated beyond its point of ignition.

In this incident, the fires were not severe either from a classical fire protection standpoint or a

nuclear safety standpoint. The most interesting aspect of this incident is the occurrence of multiple

simultaneous fires, one of which occurred in the plant’s main control room. Incidents involving

multiple initial fires have been observed in several other plants. In some cases, particularly

incidents at non-U.S. reactors, the fires have led to extensive damage.

The cause of simultaneous fires at Palo Verde was traced to a fault in the isolation transformer

located in the Train B DC equipment room. This failure caused a short-circuit fault to the station

ground through the transformer’s panel ground. The neutral leg of the transformer was not

connected to ground. Also, an inverter that served as the alternative essential lighting UPS was

improperly grounded. The ground connection of the inverter served as the return path for the

isolation transformer’s ground fault, which passed through the essential lighting power supply panel.

The conductors that carried the fault current were not designed to handle the high currents caused

by the fault. As a result, they overheated and ignited the combustible materials around them.

Clearly, the common factor leading to multiple ignitions was a common overheated electrical

conductor.
H-25

It is also interesting to note that the fires in this case were, in effect, self-ignited cable fires. An

electrical fault led to an ampacity overload on a particular cable, and the cable ignited in two

locations as a result. The units at Palo Verde are relatively new (Unit 2 construction began in 1976

and the current U.S. cable flammability standard, IEEE-383, was adopted in 1975); hence, one can

assume that the cables installed in the plant are of the low flame spread type. This incident is one

of the very few incidents, if not the only incident, where a self-ignited cable fire in low flame spread

cable has not self-extinguished. This incident appears to illustrate that the possibility of such fires

does exist at some level, although the actual frequency of such fires remains uncertain.

Reference

Information Notice 97-01, “Improper Electrical Grounding Results in Simultaneous Fires in the

Control Room and the Safe-Shutdown Equipment Room,” U.S. Nuclear Regulatory Commission,

January 8, 1997.
H-26

H.15 San Onofre Nuclear Generating Station, Unit 3, February 3, 2001

On February 3, 2001, San Onofre Unit 3, was operating at 39-percent power following a refueling

outage. While switching offsite power sources for Unit 3, a 4160kV breaker (3A0712) faulted and

initiated a fire. This resulted in a loss of power to Unit 3 nonsafety-related systems, a reactor trip,

a turbine/generator trip, and an automatic start of both Unit 3 emergency diesel generators (EDGs).

The main control room (MCR) received an annunciator fire alarm, along with a visual report of

smoke and flames at the 30-foot elevation switchgear room of the turbine building. The incident

was further complicated when the MCR annunciators were lost as a result of a tripped breaker

approximately 5 minutes into the event.

The SONGS onsite fire department was dispatched upon receipt of the fire alarm in the switchgear

room and arrived at the scene within 7 minutes. The on-scene fire department captain requested

additional support from an offsite fire department. Firefighters observed that the room was

completely filled with heavy smoke, with essentially zero visibility. The source of the heavy smoke

and heat was determined to be within the closed cubicle 4160-V switchgear cabinetry. The

firefighters also noted flames from burning instrument gauges on the front of cubicle 3B14, which

is located directly across from the 4160-V breaker cubicle. The onsite fire department captain

established a command post, initiated fire suppression using portable fire extinguishers, and began

ventilating the area. Communication between the onsite fire department captain and the plant shift

manager was through the technical advisor at the scene. The firefighters discharged portable

Halon and dry chemical fire extinguishers through the cabinet vents in an attempt to extinguish any

active fire within the cabinet. The extinguishing agents had no noticeable effect on the production

of smoke. The technical advisor transmitted to the operations shift manager a report that the fire

was out, although the fire department captain only advised the operations technical advisor that

flames were no longer visible.

With the exception of some low-voltage circuits, all power was isolated to the 4160-V switchgear.

The firefighters then determined that the cubicle door could be opened safely. Upon opening the

cubicle door, the firefighters observed flames within the cubicle, and discharged additional dry

chemical in another attempt to extinguish the flames. The firefighters then closed the cubicle door

as a containment measure. The cubicle door was subsequently opened several times, and each

time the door was opened, in-rushing air caused the fire to reflash. Firefighters then used dry

chemical each time the fire reflashed.

The fire department captain advised the operations technical advisor that the fire could not be

completely extinguished unless the firefighters applied water to the fire. It appeared that the dry

chemical temporarily removed air from the fire, but did not reduce the heat, and the fire would

reflash once air was reintroduced. The operations technical advisor relayed this request to the shift

manager for permission to use water on the smoldering area inside the cubicle to prevent reflash.

Because he was concerned that the buses were still energized with 125-V dc and low-voltage ac

power, the shift manager initially denied the fire department captain’s request to use water.

However, after the fire department captain spoke directly with the shift manager to advise him that

the deep-seated fire could not be extinguished unless water was applied, the shift manager granted

permission to use water to extinguish the fire. The fire was ultimately extinguished after firefighters

applied water. The deep-seated fire burned for approximately 3 hours before finally being

extinguished. The licensee later determined that communication weaknesses in identifying the

actual fire status during the event contributed to the delay in extinguishment.
H-27

Discussion

The extensive damage made it difficult to determine the exact cause of the fault. The licensee

found that the 4160-V switchgear phase C arcing contact had completely melted, and concluded

that the phase C circuit breaker failed to close completely during the bus transfer. The breaker was

approximately 25 years old and had its last preventive maintenance performed in 1997. The

licensee also believed that arcing, fire, smoke, and ionized gases in the 4160-V circuit breaker

caused multiple faults on a 3A07 bus and the offsite power circuit terminal connection at circuit

breaker 3A0714.

The licensee also determined that the fire event generated a much higher heat release rate (HRR)

than would normally be assumed in typical fire risk modeling to perform probabilistic risk

assessment (PRA). In “A Supplement to EPRI Fire PRA Implementation Guide (TR-105928),”

report SU-105928, the Electric Power Research Institute (EPRI) provides data for electrical cabinet

fires, indicating an HRR of either 68.60 kW or 200.50 kW (65- or 190 Btu/sec), depending on the

type of cable installed. The EPRI data focus on the HRR contributions of combustibles in the

electrical cabinet (only cable insulation) and neglect the large amounts of electrical energy that may

be released from electrical faults. According to a report by the NRC’s Office of Nuclear Regulatory

Research, entitled “Operating Experience Assessment Energetic Faults in 4160-V kV to 13800-V

Switchgear and Bus Ducts That Caused Fires in Nuclear Power Plants in 1986–2001” (ADAMS

Accession #ML021290358, February 28, 2002) for medium- and high-voltage applications, the

research indicates that these HRR values [68.60 kW and 200.50 kW (65- and 190 Btu/sec)] may

be under predicted by a factor of 1,000.

This operating experience indicates that equipment rated at 4160-V and higher is vulnerable to

particularly energetic electrical faults. This event demonstrates that energetic electrical faults

instantaneously release large amounts of electrical energy and may bypass the normal fire initiation

and growth stages. In the SONGS fire event, the equipment that caught fire was directly connected

to the auxiliary transformer (AT), which is powered from the grid or main generator. If a circuit

breaker is stuck or slow in responding, there is sufficient energy to cause an explosion and vaporize

metal in a few cycles.

Conclusion

This event demonstrates the importance of using water to extinguish deep-seated electrical cable

fires. It is similar to previous fire events (Browns Ferry 1975, Waterford 1995) in which delayed

application of water on electrical fires extended the duration of the fires and delayed recovery from

the events. It is essential that fire brigade and operator training address the appropriate use of

water in firefighting operations in energized electrical equipment. This event also highlights that

the HRR from fires in electrical cabinets may be much greater than assumed in NPP fire hazard

analysis (FHA).
H-28

References

Inspection Report No. 50-362/01-05, “San Onofre Nuclear Generating Station NRC Special Team

Inspection Report,” U.S. Nuclear Regulatory Commission, April 20, 2001.

Preliminary Notification, PN401004, “Circuit Breaker Failure and Fire, Resulting in Reactor

Shutdown,” U.S. Nuclear Regulatory Commission, February 6, 2001.

Significant Event Notification, SEN 218, “Circuit Breaker Fault Results in Fire, Loss of Offsite Power,

Reactor Scram, and Severe Turbine Damage,” San Onofre Nuclear Generating Station Unit 3,

March 9, 2001.

Significant Event Report, SER 5-01, “4-kV Breaker Failure Resulting in a Switchgear Fire and

Damage to the Main Turbine Generator,” San Onofre Nuclear Generating Station Unit 3, September 21,

2001.
H-29

H.16 Point Beach Nuclear Plant, Unit 1, April 24, 2001

On April 24, 2001, while Point Beach Unit 1 was shut down and defueled for refueling outage

U1R26, a fire occurred in the “A” steam generator (S/G) vault on the access platform to the primary

side manway covers. The fire was believed to originate as the result of a short in a 12-Vdc

communication box. The fire consumed a bag of rags and testing equipment debris, and lasted for

approximately 23 minutes. After multiple failed attempts in which the fire brigade discharged

approximately 70 pounds of dry chemical (3 portable fire extinguishers), the fire was finally

extinguished using 15–20 gallons of water. The licensee reported that approximately 50 percent

of the containment basement floor (8 feet elevation), 50 percent of the “A” S/G vault, and 30 percent

of the “A” reactor coolant pump (RCP) vault were covered in white dust (dry chemical fire

extinguishing agent). Also, a white dust layer was visible on components on the main refueling floor

(66 feet evaluation). Smoke and soot resulting from the fire left a mark about 4 feet wide by 25 feet

high against the vault wall.

Discussion

The dry chemical extinguishing agent is discharged by an inert gas when a fire extinguisher is used.

All forms of dry chemical act as extinguishing agents to suppress the flame of a fire (Friedman,

1998), but may require extensive cleanup after use, as illustrated by this event.

Most chemical extinguishing agents can produce some degree of corrosion or other damage, but

of the seven types of dry chemicals, monoammonium phosphate is especially acidic and tends to

corrode more readily than other dry chemicals, which tend to be more neutral or mildly alkaline.

Furthermore, corrosion resulting from the other dry chemicals is stopped in a moderately dry

atmosphere, while phosphoric acid generated by using monoammonium phosphate has such a

strong affinity for water that an exceedingly dry atmosphere would be needed to stop the corrosion.

Application of dry chemical agents on electrical fires is considered a safe practice from the

viewpoint of electric shock. However, these agents, especially monoammonium phosphate, can

damage delicate electrical equipment.

One potential issue with using dry chemical extinguishers results from the sudden release of the

agent and the large area of discharge. Dry chemicals become sticky when heated and, therefore,

are not recommended for locations where it may be difficult to remove residue from equipment. It

is important to note that when water is applied to the affected areas, corrosion will occur because

moisture initiates a chemical reaction that accelerates corrosion of equipment exposed to the dry

chemical.

Dry chemicals are generally nontoxic, but can pose a health hazard when used in closed areas.

Persons who breathe concentrations of the dry chemical powder may experience respiratory

irritation and coughing. When dry chemicals are discharged into an enclosed area, impaired

breathing and reduced visibility should be considered.
H-30

Conclusion

Although the Point Beach incident lasted approximately 23 minutes, it was not a large fire in terms

of HRR. The dry chemical extinguishing agent did suppress the fire, but failed to completely

extinguish the fire (the fire reflashed twice). The fire brigade unsuccessfully attempted to extinguish

the fire with dry chemical agent three times before easily extinguishing it with a hose line (water).

A more thorough selection of extinguishing media should be considered in light of the cleanup effort

from the small fire. It is important to recognize that the fire was successfully extinguished with a

relatively small quantity of water, which required minimal post-fire cleanup.

References

Friedman, R. Principles of Fire Protection Chemistry and Physics, 3 Edition, Chapter 14, “Fire- rd

Fighting Procedures,” pp. 229-230, National Fire Protection Association, Quincy, Massachusetts.

1998.

Point Beach Nuclear Plant, Inspection Report 50-266/01-08, 50-301/01-08, U.S. Nuclear Regulatory

Commission, June 6, 2001 (ADAMS Accession #ML011580082).

“Point Beach Unit 1 Containment Fire,” Presented by the Point Beach Senior Resident Inspector,

Krohn, P.G., at the Region III Training Seminar. December 2001.

H.17 Prairie Island Nuclear Generating Plant, Unit 1, August 3, 2001

On August 3, 2001, at 8:44 p.m., an operator enroute to the Unit 1 bus 11/12 area observed fire and

smoke, but could not identify the cubicle from which it was originating. The operator entered the

bus 13/14 room and called the main control room (MCR) to report the fire. The MCR immediately

initiated the fire alarm and activated the onsite fire brigade. The MCR also notified the offsite

Red Wing Fire Department (RWFD).

The fire brigade entered the turbine building to assess the extent and exact location of the fire.

They reported flames in the upper and lower compartments of the 12-4 cubicle and along the left

side of the breaker. They also found that the door in both the upper and lower compartments of the

cubicle were blown open.

At 8:58 p.m., the fire brigade began initial suppression of the fire using three portable carbon

diox 2ide (CO ) extinguishers and one Halon extinguisher through the open front door of the breaker

cubicle. The fire was not extinguished, and the fire brigade observed electrical arcing in cubicle 12-4.

The fire appeared to be localized in one area and not spreading. The initial efforts to deenergize

the bus from the MCR failed. The fire brigade chief reported to the MCR that breaker 12-4 was still

energized, as evidenced by arcing observed in cubicle 12-4. Because of the uncertainty as to

whether bus 12 was deenergized, the Unit 2 shift supervisor decided to deenergize the 1R

transformer. The fire department reported to the MCR that there were small flames and heavy

smoke in breakers 12-1 and 12-4. At 10:13 p.m., approximately 1.5 hours into the event, the fire

brigade extinguished the fire with assistance from the RWFD.
H-31

Discussion

The 2 fire was extinguished after 1.5 hours by using more than 20 portable CO fire extinguishers in

2

the evolution (in addition to the 3 CO extinguishers and 1 Halon extinguisher used in the initial

attack). One factor that complicated extinguishing the fire was the decision not to use water

because of energized electrical equipment. This resulted in continued burning and elevated

temperature. Because of the elevated temperature caused by this electrical fire, two fire brigade

members were treated for heat exhaustion at the site, and one of them was subsequently

transported to the hospital for further treatment. In addition, several inches of the copper feed stabs

from the 1M transformer completely vaporized during this fire (providing additional evidence of high

temperature).

The licensee determined that the cause of the event was a poor electrical connection between the

breaker 12-4 C-phase primary disconnect assembly (PDA) and the 1MY bus stab, which caused

the PDA to overheat. The arcing also actuated the protective relaying, which resulted in an

automatic turbine/reactor trip. The arcing event at breaker 12-4 released enough energy to cause

the cubicle to expand and the door to be blown open. The breaker compartment was heavily

oxidized and holes were burned through the cubicle on either side of the breaker. The arcing event

destroyed many of the springs and fingers in the PDAs. A few were found at the very bottom of the

debris, particularly below C phase.

Conclusion

The root cause evaluation of the nonsafety-related breaker fire concluded that maintenance

practices could have contributed to the failure of the PDA by creating a poor connection, which

caused localized over heating of parts of the PDA. This overheating caused the PDA to

disintegrate. At that point, the loose parts of the PDA created a short-to-ground path. Once the

arc was struck, phase-to-phase faulting occurred between the A-B and B-C phases. The initial

arcing to ground quickly interrupted the dc circuit below the breaker pan (located directly below the

PDA).

2

In this fire event, the use of portable CO and Halon fire extinguishers may not have been the most

effective choice of extinguishing agent to use. Operating experience in energized electrical

equipment fires shows that the use of a relatively small quantity of water was effective in successful

fire extinguishment.

References

Preliminary Notification PN301027, “Electrical Panel Fire During Plant Startup,” Prairie Island

Nuclear Generating Plant, Unit 1, U.S. Nuclear Regulatory Commission, August 6, 2001.

Licensee Event Report (LER) 1-01-05, “Fault and Fire in Non-Safeguards Circuit Breaker Results

in Reactor Trip and Auxiliary Feedwater System Actuation,” Prairie Island Nuclear Generating Plant,

Unit 1, October 2, 2001.
H-32

H.18 Fort Calhoun Station, Unit 1, December 19, 2001

In October 2001, the licensee for Fort Calhoun Station began a surveillance of the Unit 1

containment prestressing system. This surveillance included testing the tension of the containment

concrete tensioning cables. It also involved pumping lubricating grease into the containment

tendon sheathings to replace the grease that had been lost as a result of leakage. In support of

this activity, 55-gallon drums of grease were located in the tension gallery. During this surveillance

activity, the plant personnel discovered that the grease was too cold to pump and would need to

be heated before use. Drum heaters were, therefore, used on the outside of the drums to heat the

grease and facilitate pumping into the containment tension sheathings. Two drum heaters were

used, one powered from a receptacle located in the tension gallery and the second powered from

a receptacle located in room 22. In order to supply power from the outlet in room 22 to one of the

drum heaters, two extension cords were connected in series and routed through the open door

separating room 22 from the tension gallery. At the end of the day, the drum heater powered from

the receptacle in room 22 was left energized to keep the grease warm overnight so that work could

begin the next morning.

Unbeknownst to plant personnel involved in performing the surveillance, the extension cords used

to power the drum heater were not rated for this application. The extension cords were rated at 15

amperes, and had male connections that would only allow them to be connected to 15-ampere

receptacles. However, the 20-ampere male connection on the drum heater had been

inappropriately modified to allow it to be connected to a 15-ampere plug or receptacle. The

licensee later determined that the 2,000-watt drum heater drew a current of 17.39 amperes.

As a result of using underrated extension cords, the extension cords continued to heat up during

the evening. The extension cords eventually overheated and ignited the plastic on the radiological

control point stepoff pad and a rubber air hose.

On December 19, 2001, at 2:48 a.m., the MCR operators received an alarm from an ionization

smoke detector located in room 22. A control room operator dispatched the auxiliary building

operator and a radiation protection technician to investigate the cause of the fire alarms. The

auxiliary building operator arrived at the door to room 22, cracked the door open, and determined

that there was too much smoke to enter the room without using protective firefighting bunker gear

and a self-contained breathing apparatus (SCBA) and informed the MCR. The fire brigade was

activated while operators entered the abnormal operating procedure for fighting fires. During this

event, the MCR received another ionization smoke detector alarm in corridor 4.

The fire brigade laid out an attack line from the hose cabinet outside room 22 and a backup line

from the cabinet outside room 6 before the attack team prepared to enter room 22. The attack team

entered room 22 and proceeded down the stairs toward the entrance to the containment tension

stressing gallery. The nozzle man described room 22 as being completely filled with smoke with

no visibility. The smoke that traveled from room 22 through the open door caused the actuation of

the water curtain open head deluge system on the auxiliary building stairwell, which resulted in

water being sprayed onto safety-related motor control centers (MCCs), which subsequently caused

actuation of the 480-V bus ground alarms in the MCR.

These MCCs are safety-related but are not required to function during a safe shutdown event, as

defined by Appendix R to Title 10, Part 50, of the Code of Federal Regulations (10 CFR Part 50).

Operators also restarted the room 22 ventilation to remove the smoke.
H-33

Discussion

Licensee personnel performed unauthorized modifications to the male connections of two drum

heaters, allowing them to be inserted into underrated outlets and extension cords, which ultimately

caused the fire. The licensee concluded that the root cause of the fire was the modification of the

male connection on a 2,000-watt drum heater. The plug on a second 2,000-watt drum heater was

also found to be modified. This unauthorized modification defeated a manufactured safety device

(electrical connector standards), thereby allowing the heaters to be energized using undersized

extension cords and electrical outlets. On one of the plugs, a prong was twisted 90 degrees to

make it similar to a 15-ampere plug. On the other heater, the plug was completely removed and

replaced with a 15-ampere plug (see illustrations below).

Conclusion

The fire was a result of modified plugs on two drum heaters, which defeated the intent of the design

of electrical outlets. The licensee failed to with comply the procedural requirements for a temporary

modification. The heavy smoke from the fire caused a deluge sprinkler system to actuate in a

different fire area which sprayed on safety-related electrical equipment. 10 CFR 50.48(a) requires

licensees to have a fire protection plan that meets General Design Criterion (GDC) 3 of Appendix A

to 10 CFR Part 50. GDC 3 requires that structures, systems, and components that are important

to safety shall be designed and located to minimize, the probability and effect of fires and

explosions, consistent with other safety requirements.

Reference

Fort Calhoun Station NRC Special Team Inspection Report, 50-285/02-06, U.S. Nuclear Regulatory

Commission, April 5, 2002 (ADAMS Accession #ML020960001).

I-1

APPENDIX I. MATHEMATICS REVIEW AND SYSTEM OF UNITS

This appendix provides the essential, mathematical foundation for quantitative fire hazard analysis.

I.1 Mathematics Review

While it was our goal to minimize the use of mathematics as much as possible, there is a need to

use some relatively simple mathematics to understand the principles of fire dynamics used in this

NUREG. The mathematical methods used in this NUREG hinge on an understanding of units of

measurement, the ability to read various types of graphs, the ability to solve simple algebraic

equations and to determine the unit consistency of an equation, and the ability to use simple

functions commonly found on a basic scientific calculator. The spreadsheets were designed with

this in mind, i.e., each sheet shows equations and variables being input. It was the authors’ goal

to further the science of fire dynamics, while not burdening the users down with complex

mathematical operations. Likewise it’s the users’ responsibility to use the spreadsheets to gain an

understanding of fire dynamics and not view them as “black boxes.”

I.1.1 Units of Measurement

Fire dynamics most often uses units of measure from the system international (SI) metric system.

While this may seem foreign at first, the transition to metric units is relatively easy and, once

mastered, the metric system is much easier to use than English units of measure. Many of the

spreadsheets are designed to allow the user to enter the information in English units, the

spreadsheet will convert them to SI units, solve the problem and convert the answer back to English

units.

Table I.1-1 summarizes the basic units of measure. These are units of length, mass, time,

temperature, electric current, amount of light, and quantity of matter. All other units can be derived

from these seven basic units. For instance, velocity (or speed) is a derived unit, expressed as

meter per second (m/s), which is formed from the units of length and time.

Table I.1-1. Basic Units

Units of Measure Symbol Unit (SI) SI Symbol

Length L meter m

Mass m kilogram kg

Time t second s

Temperature T Celsius, Kelvin °C, K

Electric current A ampere A

Amount of light cd candela cd

Quantity of matter mol mole mol
I-2

Table I.1-2 presents a partial listing of the derived units that are useful in fire dynamics. The table

does not include units relevant to electricity, magnetism, or other areas that are not relevant to fire

dynamics. Note that some units named after individuals are capitalized, while other units are not.

For example, because the unit of power (watt) is named for James Watt of steam engine fame; the

abbreviation (W) is capitalized.

Table I.1-2. Derived Units

Unit of Measure Unit (SI) SI Symbol

Acceleration meter per square second m/s2

Area square meter m

2

Density kilogram per cubic meter kg/m3

Energy joule (J) N-m

Force newton (N) Kg-m/s2

Frequency hertz (Hz) l/s

Heat (quantity) joule (J) N-m

Heat flux kilowatts per square meter kW/m2

Illuminance lux (lx) lm/m2

Luminance candela per square meter cd/m2

Luminous flux lumen (lm) lm/m2

Power (heat release rate) watt (W) J/s

Pressure pascal (Pa) N/m2

Radiant intensity watt per steradian W/sr

Specific heat joule per kilogram-kelvin J/kg-K

Stress pascal (Pa) N/m2

Thermal conductivity watt per meter-kelvin W/m-K

Velocity meter per second m/s

Viscosity, dynamic pascal-second Pa-sec

Viscosity, kinematic square meter per second m /s 2

Volume cubic meter m

3

Work joule (J) N-m
I-3

Simple units of the types shown in Table I.1-1 and I.1-2 can be cumbersome if the magnitudes are

very large or very small. For example, it is problematic to speak of distances between cities in

meters (as in “City A is 5,000 meters from City B”). While this distance may be accurate, meters

is not the most convenient unit in terms of magnitude. To avoid very large and very small numbers,

the metric system uses prefixes to modify the magnitude of the basic unit. For example, 5,000 m

is equivalent to 5 km. The prefix k refers to kilo and indicates multiplication by 1,000. Table I.1-3

lists the common prefixes used in the metric system form names and symbols of multiples (decimal

multiples and sub-multiples) of the SI units. While these prefixes are optional, they often simplify

matters. The distance in the example above (5,000 m or 5 km) is a common foot race distance,

which is often further simplified by referring to a 5-k race.

Table I.1-3. SI Prefixes

Multiplication Factors Prefix SI Symbol

1 000 000 000 000 = 10

12

1 000 000 000 = 10

9

1 000 000 = 10

6

1 000 = 10

3

0.01 = 10-2

0.001 = 10-3

0.000 001 = 10-6

0.000 000 001 = 10-9

0.000 000 000 001 = 10-12

0.000 000 000 000 001 = 10-15

0.000 000 000 000 000 001 = 10-18

tera

giga

mega

kilo

centi

milli

micro

nano

pico

femto

atto

T

G

M

k

c

m

n

p

f

a
I-4

Table I.1-4 introduces another useful concept, known as scientific notation. Rather than writing out

1,000,000, it is useful to use scientific notation, which indicates the number of zeros as an

exponent. In Table I.1-3, we see an entry for the prefix mega, which refers to multiplication by

1,000,000 or, in scientific notation, 10 or 10E+06. Thus, a distance of 5,000,000 m could be 6

expressed as 5 x 10 m or 5 Mm. We see that scientific notation has essentially the same function 6

as the prefixes.

Table I.1-4. Scientific Notations, Prefixes, and Abbreviations

Multiplier Prefix Abbreviation

10 tera T

12

10 giga G

9

10 mega M

6

10 kilo k

3

10 hecto h

2

10 centi c

-2

10 milli m

-3

10 micro -6

10 nano n

-9

10 pico p

-12

10 atto a

-18

While the information required for use in fire dynamics is generally available in metric units, the data

are sometimes available only in English units and conversion to metric is needed. Table I.1-5 gives

some of the most common conversions required for fire dynamics. These conversions are simple

to apply. For example, to convert from feet to meter, multiply the number of feet by 3.048 x 10-1

(0.3048) to get the number in meters. Many of the spreadsheets have this conversion features built

into the sheet.

Table I.1-5. Selected Unit Conversions

To Convert from To Multiply by

Area

 foot2

 inch2

meter (m )

2 2

meter (m )

2 2

9.290304 x 10-2

6.451600 x 10-4

Energy/Area Time

 watt/centimeter2

watt/meter (W/m ) 1.0 x 10 2 2 4

Length

 foot

 inch

meter (m)

meter (m)

3.048 x 10-1

2.540 x 10-2
Table I.1-5. Selected Unit Conversions

To Convert from To Multiply by

I-5

Mass/Area

 pound-mass/foot2

kilogram/meter (kg/m )

2 2

4.882428 x 100

Mass/Volume (including

Density and Mass Capacity)

 pound-mass/foot3

kilogram/meter (kg/m ) 1.601846 x 10 3 3 1

Pressure

 atmosphere

 bar

 inch of mercury

 inch of water

 pound-force/inch (psi) 2

 torr mm Hg (°C)

Pascal (Pa)

Pascal (Pa)

Pascal (Pa)

Pascal (Pa)

Pascal (Pa)

Pascal (Pa)

1.01325 x 105

1.0 x 105

3.37685 x 103

2.4884 x 102

6.894757 x 103

1.33322 x 102

Temperature

 degree Celsius

 degree Celsius

 degree Celsius

 degree Fahrenheit

 degree Fahrenheit

 degree Fahrenheit

 Kelvin

 Kelvin

 Kelvin

 Rankine

 Rankine

 Rankine

degree Fahrenheit (°F)

Kelvin (K)

Rankine (R)

degree Celsius (°C)

Kelvin (K)

Rankine (R)

degree Celsius (°C)

degree Fahrenheit (°F)

Rankine (R)

degree Celsius (°C)

degree Fahrenheit (°F)

Kelvin (K)

9/5 °C + 32

°C + 273.15

5/9 (R + 491.67)

5/9 (°F - 32)

5/9 °F + 255.37

°F + 459.67

K - 273.15

9/5(K - 255.37)

9/5 K

5/9 (R - 491.67)

R - 459.67

5/9 R

Time

 day (mean solar)

 hour (mean solar)

 minute (mean solar)

second (s)

second (s)

second (s)

8.640 x 104

3.60 x 103

6.0 x 101

Velocity (includes Speed)

 foot/second

 mile/hour

meter/second (m/s)

meter/second (m/s)

3.0480 x 10-1

4.4704 x 10-1

Volume (including Capacity)

 foot3

 gallon (U.S. liquid)

 liter

meter (m )

3 3

meter (m )

3 3

meter (m )

3 3

2.831685 x 10-2

3.785412 x 10-3

1.0 x 10-3
I-6

The approach taken in converting from customary English units to SI units has been to retain the

precision of the original measurement. For example, “It is about 8-miles,” properly translates to “It

is about 13 kilometers.” Thus, would be inappropriate to convert the imprecise 8-mile measurement

to a precise value of 12.875 kilometers (based on the exact conversion). The degree of precision

implied by such an exact conversion is simply not implied by the original measurement. Therefore,

conversions have been chosen to properly reflect the precision of the original measurement. For

example, a 12-foot run of sprinkler piping converts to 3.7 meters, if the piping is measured to the

nearest inch. If measured to the nearest foot, the appropriate conversion is 4 meters.

For the most part the SI units into which quantities have been converted follow the SI practice of

expressing a quantity so that its numerical value falls between 0.1 and 1,000. For example, 14.7

psi would be converted to 101 kPa, not 101,000 Pa. Some deviations from this practice have been

allowed in instances where several values of the same quantity are being compared or presented

in tabular form. For example, if four fire test samples have masses of 500 kg, 800 kg, 900 kg, and

1,200 kg, it would be inappropriate to express the last entry as 1.2 Mg.

I.1.2 Math Functions

This section discusses several mathematical functions that are common to many of the equations

and empirical correlations used in fire dynamics. These functions can all be calculated using a

simple scientific hand calculator.

(1) A “power” is an exponent (x) that operates on a base (y) real number in the function y .

x

When the power is a whole number, the function can be expressed as the base multiplied

by itself the number of times indicated by the power.

y = (3.2) = (3.2) x (3.2) x (3.2) = 32.768 x 3

When the same base (y) is raised to different powers and the quantities are multiplied, the “powers”

are added, as illustrated by the following examples:

(a)

(b)

Similarly, when the same base (y) is raised to different powers and the quantities are divided, the

powers are subtracted as illustrated by the following examples:

(a) 

(b) 
I-7

By contrast, when a power (x) is raised to another power, they multiply, as illustrated by the

following example:

Finally when a number or variable has no “power,” it is assumed to be raised to the power of 1

because any “base” raised to the “power” of 1 is equal to the “base” as illustrated by the following

examples:

(Z) = Z 1

(Q) = Q 1

In summary, the following examples are valid mathematical equations using powers:

(a)

(b)

(c)

A scientific calculator typically has a y button. x

(2) A logarithm is an exponent indicating the power to which a fixed number (the base) must

be raised to produce a given number. For example, if n = a, then the logarithm of a, with x

n as the base, is x, as illustrated by the following function:

LOGn (a) = x

Scientific calculators typically have two logarithmic buttons typically identified as LOG and LN.

In such cases, LOG returns the logarithm of the imputed value using a base equal to 10.

This common logarithm functions as follows:

LOG10 (value entered) = x (value calculator returns)

By contrast, LN returns the logarithm of the imputed value using the base equal to “e,”

which is the real number for which the natural logarithm is 1 (.2.718). This “natural

logarithm” function as follows:

LOGe (value entered) = x (value calculator returns).
I-8

I.1.3 Solving Equations

“Equation solving” is a central theme in mathematics which is considerably broader than the

treatment given here. The FDT we are using for fire hazard analysis (FHA) is simply based on s

algebraic equations, in which we substitute numbers for the variables and calculate a numerical

result. This calculation hinges on inserting numbers for the variable names with units included, and

then checking or adjusting the units to ensure dimensional consistency through a process called

dimensional analysis. This process is based on the principle that units associated with numbers

are operated on, just as the numerical values are, through algebraic manipulations.

Units follow the rules set forth for powers, because units can also have associated powers:

• When divided, units cancel through power subtraction, as illustrated by the following

examples:

(a)

(b)

• When multiplied units combine through power addition, as illustrated by the following

examples:

(a)

(b)

• When raised to other powers, unit powers are multiplied, as illustrated by the following

examples:

• The horizontal flame spread rate on thick solid fuels equation is a good illustration:

Where:

V = flame spread rate (m/sec)

 = a flame spread modulus (kW) /m (determined experimentally) 2 3

k c = thermal inertia (kW/m K) sec 2 2

Tig = material ignition temperature (°C)

Ta = initial material temperature (°C)
I-9

The literature provides the following data for plywood:

 = 12.9 (kW) /m2 3

k c = 0.54 (kW/m K) sec 2 2

Tig = 390 °C

We cannot a solve for the flame spread rate until we select a material temperature T .

Indeed, the point of the equation is to show how the flame spread rate varies with material

and mater aial temperature. As an example, let’s use T = 200 °C. Substituting the numerical

values in the equation, we can compute the flame spread rate on plywood, as follows:

We can now use a calculator to perform the multiplications and division to obtain an answer

as follows:

It remains to check the consistency of the units. The kW and m in the above equation, 2 3

as follows:
I-10

At first inspection, it does not appear that the two temperature units will cancel, even though

they are both raised to the power of 2. However, because the °C unit comes from a 2

temperature difference, it will cancel because the only difference between °C and K is an

added constant. Thus, to convert from °C to K, you add 273, as follows:

(390 °C - 200 °C) = [(390 °C + 273 K) - (200 °C + 273 K)] 2 2

 = [663 K - 473 K]2

 = 190 K2

The result in terms of temperature differentials ( T), 190 °K is the same as 190 °C . 

2 2

If the °C term were not different, it would require the conversion to K . Thus, in this case, 2

the °C and the K units cancel. 2 2

The resulting unit is m/s as follows:

Thus, the result is complete and the units are consistent and reasonable. Meter/second

(m/s) is the unit of velocity as the equation indicated it should be.

I.1.4 Cautions with T Conversions

A word of caution is in order about converting temperature between Celsius (°C) and Fahrenheit

(°F). For conversion between the temperature scales:

°F = (°C x 1.8) + 32

°C = (°F - 32) / 1.8

For example, to convert the temperature 250 °F to °C:

°C = (250 °F - 32) / 1.8

 = (218) / 1.8

 = 121.11 ~121 °C

However, to establish a ratio, such as a temperature rise ( T):

)°F = ()°C x 1.8)

)°C = ()°F / 1.8)
I-11

For example, to convert a temperature rise ( T) of 250 °F to °C, instead of converting:

32 °F ÷ 282 °F (DT = 250 °F)

 ù ù ù

 0 °C ÷138.9 °C (DT = 139 °C)

the same will result from:

°C = (250 °F / 1.8)

 = 138.89 ~ 139 °C

Note that ASTM E119, “Standard Test Method for Fire Tests of Building Construction and

Materials,” properly applies these conversions as illustrated in “Tests of Nonbearing Walls and

Partitions,” Section 18.1.3, “Transmission of heat through the wall or partition during the fire

endurance test shall not have been such as to raise the temperature on its unexposed surface more

than 250 °F (139 °C) above its initial temperature.”

NFPA 251, 1995 Edition, “Standard Method of Fire Tests of Building Construction and Materials,”

does not make this same conversion, “Transmission of heat through the wall or partition during the

fire endurance test shall not be sufficient to raise the temperature on its unexposed surface more

than 250 °F (139 °C) above its initial temperature.” For the purpose of this NUREG, the conversion

of ASTM E119 will be used.

I.1.5 Miscellaneous Information

The following information involves measurement of geometrical quantities in the form of diameter,

circumference, area, etc.

• To find the diameter of a circle, multiply the circumference by 0.31831.

• To find the circumference of a circle, multiply the diameter by 3.14159.

• To find the area of a circle, multiply the square of the diameter by 0.78539.

• To find the surface of a sphere, multiply the square of the diameter by 3.14159.
I-12

• To find the volume of a sphere, multiply the cube of the diameter by 0.52369.

• Doubling the diameter of a pipe or hose increases its capacity four times.

I.1.6 References

Fire Dynamics Course Guide, Federal Emergency Management Agency (FEMA), United States Fire

Administration (USFA), National Emergency Training Center, Emmitsburg, Maryland, 1995.

Qunitiere, J.G., Principles of Fire Behavior, Delmar Publishers, Albany, New York, 1997.

“Standard for Use of the International System of Units (SI): The Modern Metric System,”

IEEE/ASTM SI 10-1997, Institute of Electrical and Electronics Engineer, Inc., (IEEE), New York,

New York, and American Society of Testing and Materials (ASTM), West Conshohocken,

Pennsylvania, 1997.

Taylor, B.N., “Guide for the Use of the International System of Units (SI),” NIST Special Publication

811, 1995 Edition, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland.
I-13

I.2 Notation Conventions

This section provide various notation conventions used in fire dynamics to expressed a quantity

related to fire protection engineering, for example, heat flux density or heat release rate .

X, x Generally letters are assigned to physical phenomena. In fire protection engineering

there is often a special significance implied by either upper or lower case. The use

of notation is important in fire dynamics, upper and lower case are recommended.

The following symbols indicate additional characteristics of a single quantity to simplify both

memorization needs and dimensional verification of calculations.

A dot over a letter means that quantity “per unit time” (e.g., rate).

A double dot over a letter means that quantity “per unit time per unit time”

(e.g., acceleration is the change in velocity over a period of time).

An apostrophe to the right of a letter means that quantity “per unit length.”

Two apostrophies to the right of a letter signifies that quantity “per unit area.”

Three apostrophies to the right of a letter means that quantity “per unit volume.”

A bar over a letter means the arithmetic average value (the mean value) of varying

quantity.

The following usage conventions also apply to the equations used in FHA.

Notations may be combined as needed.

kW With unit abbreviations, it is customary to use a capital letter when the abbreviation

signifies a person’s name (e.g., W for Watt, kW for kilowatt).

x/y Units in the denominator are generally shown without a prefix (s, m, etc.), but there

is an exception (i.e., kg).

x/(y z ) Quantities with more than one unit in the denominator are shown with the 0

denominator in parentheses and units separated by a space.

I.2.1 Reference

SI Units Fire Protection Engineering, 1980 Report of the Measurement of Fire Phenomena

Committee, Society of Fire Protection Engineers (SFPE), Boston, Massachusetts, March 1980.
I-14

I.3 System of Units

When expressing a physical quantity by a numerical value, a unit must be selected for that quantity

defined by appropriate notation, letters or symbols. Certain units are by convention regarded as

dimensionally independent; these units are called base units, and all other units (derived units) can

be expressed algebraically in terms of the base units. The following section describes the

fundamental basic and derived units of measurements.

I.3.1 Length, Area, and Volume Units

The basic SI unit of length is the meter (m). Originally, the meter was selected as one ten-millionth

of the distance from earth’s equator to the North Pole.

The basic SI units of area are square meter (m ), square centimeter (cm ), and so on. Land areas 2 2

are expressed in hectares (ha); 1 hectare is 10,000 m . The English equivalent of the hectare is 2

2.47 acres.

Similarly, volume is expressed in cubic meters (m ), cubic centimeters (cm ), and so on. The liter 3 3

(L), which is also is commonly used as a unit of volume, is the same as 1 cubic decimeter (dm ) or 3

1,000 cubic centimeters (cm ). The English equivalency of the liter is 0.264 U.S. gallons. 3

I.3.2 Mass and Density Units

The basic SI unit of mass is the kilogram (kg). The kilogram was selected because it is

approximately the mass of 1 liter of water. The gram (g), also widely used, is one one-thousandth

of a kilogram, which is approximately the mass of 1 cubic centimeter of water. (Water expands or

contracts slightly as its temperature changes.)

Density (mass per unit volume) is generally expressed in grams per cubic centimeter (g/cm ) or 3

kilograms per cubic decimeter (kg/dm ). The numerical value of density is the same in either of 3

these units. “Specific gravity” refers to the ratio of the density of a substance to that of liquid water.

Confusion often exists between mass and weight. Weight refers to the force acting on an object

because of gravitational attraction. As such, it is a convenient way to measure mass at sea level

on earth. However, if an object were on the moon, its weight would be only about one-sixth of its

weight on earth and in an orbiting space station, the object would be weightless; however, its mass

would be the same in each case as it is on earth. The mass of an object is the sum of masses of

its constituent atoms and is invariant (except in a nuclear bomb explosion, when mass changes into

energy). This fact can be proved by an experiment measuring the inertia of an object (the force

needed to accelerate it the object).

I.3.3 Time Units

Units of time are the same in the SI system as in the English system. The basic unit is the second.
I-15

I.3.4 Force and Pressure Units

The basic unit of force in the SI system is the newton (N). A newton is the force needed to

accelerate a mass of 1 kg at the rate of 1 m/sec . In the English system, 1 lb of force will accelerate 2

1 lb of mass at the rate of 32.2 ft/sec . This definition was selected so that 1 lb of mass at sea level 2

would feel a gravitational attraction of 1 lb of force.

From the relationships between the pound and the kilogram, and between the foot and the meter,

it is easy to show that a newton is equal to 0.224 lb of force. The gravitational force on 1 kg of

mass at sea level is 9.81 N.

Pressure is force per unit area. The basic SI unit of pressure is the pascal (Pa), which is 1 N/m .

2

One Pa is a very low pressure; therefore, we also use a unit called the bar, which is defined as

100,000 Pa or 100 kilopascals (kPa). One bar is only 1.3 percent greater than normal atmospheric

pressure at sea level; therefore, 1 bar is nearly equal to 1 atmosphere (atm).

In the English system, pressure is often expressed in pounds per square inch (psi) or in inches of

wa 2ter (H O) or mercury (Hg). One bar equals 14.89 psi and kPa equals 4.02 in. of water.

I.3.5 Energy Units

The basic SI unit of energy is the joule (J). A joule is the quantity of energy expended when a force

of 1 N pushes something a distance of 1 m. Both thermal and mechanical energy can be

expressed as joules. One joule equals 0.239 calorie (cal), and 4.187 J equals 1 cal. (A calorie is

the energy needed to heat 1 g of water 1 °C; a dietitian’s calorie is actually 1,000 calories.)

Electrical energy can also be expressed in joules; in the case, 1 J equals 1 watt-second (Ws) and

one megajoule (MJ) (1,000,000 J) equals 0.278 kilowatt-hour (kW-h). For example, if a power of

1 kW is released in an electric iron for 0.278 h, 1 MJ of thermal energy has been released.

In English units, energy is expressed in foot-pounds (ft-lb) or British thermal units (Btu). One ft-lb

is equal to 1.355 J, and 1 Btu is equal to 1,044 J or 252 cal.

I.3.6 Power Units

Power is the rate at which energy is expended. In SI units, power is expressed in watts (W),

kilowatts (1,000 W) or megawatts (MW) (1,000,000 W). One watt is 1 J/sec. In English units,

power is expressed as horsepower (hp), where one horsepower equals 745 W. Also, note that 1

Btu/sec equals 1.055 kW. (For first order approximation, 1 Btu/sec roughly equals 1 kW).
I-16

I.3.7 Temperature Units

The SI system uses both the Celsius (°C) and Kelvin scale (K) temperature scales. A Celsius

degree (previously called centigrade) is one one-hundredth of the difference between the

temperature of melting ice and boiling water at a pressure of 1 atmosphere (atm). On the Celsius

scale (at sea level), 0° is the melting point of ice (or the freezing point of water) and 100° is the

boiling point of water. Negative temperatures are possible.

On the Kelvin scale (Celsius absolute), sometimes called the thermodynamic temperature, the zero

point is called “absolute zero” and equals -273.15 °C. No temperature colder than this is possible;

that is, negative temperatures are not possible. The Kelvin scale is expressed in Kelvin, not

degrees Kelvin.

Other features of the Kelvin scale indicate its basic nature:

• The volume occupied by a gas is proportional to its temperature on the Kelvin scale, as long

as its pressure is held constant (except at pressures far above atmospheric pressure).

• The thermal radiation emitted by an opening in a hot furnace is proportional to the fourth

power of the Kelvin temperature.

• The velocity of sound through a gas is proportional to the square root of its Kelvin

temperature.

Because of these and other scientific facts, it would be logical to use only the Kelvin scale for

temperature. However, the world continues to use both scales because the Celsius was used for

more than century before these facts were discovered.

By contrast, the English system uses the Fahrenheit temperature scale (°F). One Fahrenheit

degree is 1one eightieth of the difference between the temperature of melting of ice and boiling

water at a pressure of 1 atm. On the Fahrenheit scale (at sea level), 32 °F is the melting point of

ice (or the freezing point of water), and 212 °F is the boiling point of water.

I.3.8 References

ASTM E-380-93, “Standard Practice for Use of the International System of Units (SI)

(the Modernized Metric System),” American Society for Testing and Materials (ASTM),

West Conshohocken, Pennsylvania.

IEEE/ASTM SI 10-1997, “Standard for Use of the International System of Units (SI): The Modern

Metric System,” Institute of Electrical and Electronics Engineer, Inc., (IEEE), New York, New York,

and American Society of Testing and Materials (ASTM), West Conshohocken, Pennsylvania, 1997.

Taylor, B.N., “Guide for the Use of the International System of Units (SI),” NIST Special Publication

811, 1995 Edition, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland.
I-17

I.4 Physical Constants for General Use

Table I.4.1 provides common values of physical constants used in the fire dynamics and other

engineering and scientific calculations. Table I.4.1 show the values of several different constants

in SI units having special names and symbols.

Table I.4-1. Values of Constants for General Use

Constant Name Symbol Value SI Unit

Standa ard atmospheric pressure P 100 kPa

Absolute zero (temperature) T 0 K

Standard acceleration due to gravity g 9.80665 m/s2

Ve alocity of sound in air (P , 20 °C, 50% R.H.) M 344 m/s

Specific volume of perfect gas at standard

temperature and pressure

Va 22.414 m /(k-mol) 3

Cha aracteristic gas constant for air R 287.045 J/(kg K)

Cha vracteristic gas constant for water vapor R 461.52 J/(kg K)

Natural logarithms e 2.7182818285 –

Pi 3.1415926536 –

Stenfan-Boltzman constant 5.67032 x 10 kW/(m K )

-11 2 4

I.4.1 Reference

SI Units Fire Protection Engineering, 1980 Report of the Measurement of Fire Phenomena

Committee, Society of Fire Protection Engineers (SFPE), Boston, Massachusetts, March 1980.

J-1

APPENDIX J. PRACTICE PROBLEMS AND SOLUTIONS

This appendix contains problems to apply the principles learned in the NUREG with the FDTs

program. This appendix provides some additional practice to solve problems related to fire

dynamics.

NUREG Chapter and Related Calculation Methods

Problem NUREG Chapter FDTs

J-1 Chapter 2. Predicting Hot Gas Layer Temperature

and Smoke Layer Height in a Room Fire with Natural

and Forced Ventilation

Method of McCaffrey, Quintiere, and Harkleroad (MQH)

Compartment with Thermally Thick/Thin Boundaries

02.1_Temperature_NV.xls

J-2 Chapter 2. Predicting Hot Gas Layer Temperature

and Smoke Layer Height in a Room Fire with Natural

and Forced Ventilation

Method of Foote, Pagni, and Alvares (FPA)

Compartment with Thermally Thick/Thin Boundaries

Method of Deal and Beyler

Compartment with Thermally Thick/Thin Boundaries

02.2_Temperature_FV.xls

J-3 Chapter 2. Predicting Hot Gas Layer Temperature

and Smoke Layer Height in a Room Fire with Natural

and Forced Ventilation

Method of McCaffrey, Quintiere, and Harkleroad (MQH)

Compartment with Thermally Thick/Thin Boundaries

Chapter 2. Method of Predicting Hot Gas Layer

Temperature in Room Fire with Forced Ventilation

Method of Foote, Pagni, and Alvares (FPA)

Compartment with Thermally Thick/Thin Boundaries

Method of Deal and Beyler

Compartment with Thermally Thick/Thin Boundaries

02.1_Temperature_NV.xls

02.2_Temperature_FV.xls

J-4 Chapter 3. Estimating Burning Characteristics of Liquid

Pool Fire, Heat Release Rate, Burning Duration and

Flame Height

Heat Release Rate, Burning Duration, and Flame

Height

03_HRR_Flame_Height_Burning

_ Duration_Calculations.xls
NUREG Chapter and Related Calculation Methods

Problem NUREG Chapter FDTs

J-2

J-5 Chapter 4. Estimating Wall Fire Flame Height,

Line Fire Flame Height Against the Wall, and Corner

Fire Flame Height

04_Flame_Height_Calculations.

xls

Wall_Line_Flame_Height

Corner_Flame_Height

Wall_Flame_Height

J-6 Chapter 2. Predicting Hot Gas Layer Temperature

and Smoke Layer Height in a Room Fire with Natural

and Forced Ventilation

Method of Foote, Pagni, and Alvares (FPA)

Compartment with Thermally Thick/Thin Boundaries

Method of Deal and Beyler

Compartment with Thermally Thick/Thin Boundaries

02.2_Temperature_FV.xls

J-7 Chapter 5. Estimating Radiant Heat Flux from Fire

to a Target Fuel

Solid Flame Radiation Model 

(Target Above Ground Level, with Wind)

05.2_Heat_Flux_Calculations_W

ind_Free.xls

(Solid Flame 2)

J-8 Chapter 6. Estimating the Ignition Time of a Target

Fuel Exposed to a Constant Radiative Heat Flux

Method of Estimating Piloted Ignition Time of Solid

Materials Under Radiant Exposures. Method of

(1) Mikkola and Wichman, (2) Quintiere and Harkleroad

and, (3) Janssens

06_Ignition_Time_Calculations.xls

(Ignition_Time_Calculations1)

J-9 Chapter 7. Estimating the Full-Scale Heat Release

Rate of a Cable Tray Fire

07_Cable_HRR_Calculations.xls

J-10 Chapter 9. Estimating the Centerline Temperature of a

Buoyant Fire Plume

09_Plume_Temperature_Calcul

ations.xls

J-11 Chapter 10. Estimating Sprinkler Response Time 10_Detector_Activation_Time.xls

(Sprinkler)

J-12 Chapter 12. Estimating Heat Detector Response Time 10_Detector_Activation_Time.xls

(FTHDetector)
NUREG Chapter and Related Calculation Methods

Problem NUREG Chapter FDTs

J-3

J-13 Chapter 13. Predicting Compartment Flashover

Compartment Post-Flashover Temperature.

Method of Law.

Minimum Heat Release Rate Required to Compartment

Flashover.

Method of (1) McCaffrey, Quintiere, and Harkleroad

(MQH), (2) Babrauskas, and (3) Thomas

13_Compartment_Flashover_

Calculations.xls

(Post_Flashover_Temperature)

(Flashover-HRR)

J-14 Chapter 14. Estimating Pressure Rise Attributable to a

Fire in a Closed Compartment

14_Compartment_Over_Pressure

_Calculations.xls

J-15 Chapter 17. Calculating the Fire Resistance

of Structural Steel Members

Empirical Correlations

17.1_FR_Beams_Columns_Sub

stitution_Correlation.xls (Beam)

J-16 (a)

(b)

(c)

(d & e)

(f)

(g)

Chapter 3. Estimating Burning Characteristics

of Liquid Pool Fire, Heat Release Rate,

Burning Duration, and Flame Height

Chapter 2. Predicting Hot Gas Layer Temperature

and Smoke Layer Height in a Room Fire with Natural

and Forced Ventilation

Method of McCaffrey, Quintiere, and Harkleroad (MQH)

Compartment with Thermally Thick/Thin Boundaries

Chapter 9. Estimating the Centerline Temperature

of a Buoyant Fire Plume

Chapter 5. Estimating Radiant Heat Flux from Fire

to a Target Fuel

Wind-Free Condition

Point Source Radiation Model

(Target at Ground Level)

Solid Flame Radiation Model 

(Target Above Ground Level)

Chapter 10. Estimating Sprinkler Response Time

Chapter 13. Predicting Compartment Flashover

03_HRR_Flame_Height_Burning

_Duration_Calculations.xls

02.1_Temperature_NV.xls

09_Plume_Temperature_

Calculations.xls

05.1_Heat_Flux_Calculations_

Wind_Free.xls

(Point Source)

(Solid Flame 2)

10_Detector_Activation_Time.xls

(Sprinkler)

13_Compartment_Flashover_

Calculations.xls

(Flashover-HRR)
NUREG Chapter and Related Calculation Methods

Problem NUREG Chapter FDTs

J-4

J-17 Chapter 3. Estimating Burning Characteristics

of Liquid Pool Fire, Heat Release Rate,

Burning Duration, and Flame Height

Chapter 2. Predicting Hot Gas Layer Temperature

and Smoke Layer Height in a Room Fire with Natural

and Forced Ventilation

Method of McCaffrey, Quintiere, and Harkleroad (MQH)

Compartment with Thermally Thick/Thin Boundaries

03_HRR_Flame_Height_Burning

_Duration_Calculations.xls

02.1_Temperature_NV.xls

J-18 Chapter 3. Estimating Burning Characteristics

of Liquid Pool Fire, Heat Release Rate,

Burning Duration, and Flame Height

Chapter 8. Estimating Burning Duration

of Solid Combustibles

03_HRR_Flame_Height_Burning

_Duration_Calculations.xls

08_Burning_Duration_Solids.xls
J-5

Problem 1: Compartment Fire with Natural Ventilation

Problem J-1

Problem Statement

Consider a compartment 9.0 m wide x 9.0 m long x 3.7 m high (30 ft wide x 30 ft long x 12 ft high)

c c c v v (w x l x h ) with a door vent that is 0.92 m wide x 2.15 m high (3 ft wide x 7 ft high) (w x h ). The

fire is constant with an HRR of 1,500 kW (1,422 Btu/sec). Assume that the top of the vent is at

2.45 m (8 ft). Compute the hot gas temperature in the compartment, as well as the smoke layer

height, at 5 minutes after the ignition, assuming that the compartment boundaries are made of 2.54

cm (1.0 in) thick gypsum board.

Solution

Purpose:

g

(1) Determine the hot gas temperature in the compartment (T ) at t = 5 min after ignition.

(2) Determine the smoke layer height (z) at t = 5 min after ignition.

Assumptions:

(1) Air properties (ambient) are at 25 °C (77 °F).

(2) The ceiling is unconfined, unobstructed, and flat.

(3) The heat flow through the compartment boundaries is one-dimensional.

(4) The heat release rate (HRR) is constant.

(5) The fire is located at the center of the compartment or away from the walls.

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 02.1_Temperature_NV.xls
J-6

FDT Input Parameters: s

Enter the following parameters in the spreadsheet (values only):

c

- Compartment Width (w ) = 30 ft

c

- Compartment Length (l ) = 30 ft

c

- Compartment Height (h ) = 12 ft

v

- Vent Width (w ) = 3 ft

v

- Vent Height (h ) = 7 ft

T

- Top of Vent from Floor (V ) = 8 ft

- Interior Lining Thickness (*) = 1 in

- Select Material: select Gypsum Board from the combo box

- Fire Heat Release Rate = 1,500 kW

- Time after Ignition (t) = 5 min

Note: When Gypsum Board is selected, its thermal properties are automatically

selected from the table and entered in the corresponding input cells.

Results*

From the table of results of the spreadsheet at t = 5 minutes after ignition we obtain:

Hot Gas Layer Temperature

Tg °C (°F)

Smoke Layer Height

z m (ft)

351 (664) 2.44 (8.00)

smoke is exiting through the vent

*spreadsheet calculations attached on next page
J-7

Spreadsheet Calculations

FDT : 02.1_Temperature_NV.xls s

CHAPTER 2. PREDICTIIIG HOT GAS LAYER TEMPERA lURE AIID SMOKE 

LAVER HEIGHT Ill A ROOM FIRE WITH IIA lURAL VEIITILATIOII 

COMPARTMEIITWITH THERMALLY THICK/THIII BOUIIDARIES 

Version 19l5D 

~ 'bt)Witg ca• • h1J' " 011ate 1u •otg.u tr l,mpuatue <Ud ~ tr ••~ t~•t • u c•x •.: 111e. P.'ll'\'lffi$'rl In YEllOWCEllS llr$ Blter$d 11,' Ul$ UtH . 

P.'ll'\'lffi$'U In GREEII C EllS llr$ AUtomllU~II IV $$1$C'd TCffl 1l$ DROP OOWII t.1EIIU br1ll$ f.btel1ill h i$C,d . 

. O:..II bHq tt 1> tt •• ' <ue ca t:tl.~ by ~ P'~a:t> ~~ta d baad lt ' $pecrtd 11 1u ltptt j).'II.'IIIH' IL n a; $ple<t:I$•Ht ~ p1o-.~d <tHI$eCue bat.tot le IDI> (ft e b a WIOt ge 11r>{ II a 0:11('). 

n e c•ap' Jlt1U tiUR~ ' •o• t1 be JMdbe'bte at a~<lll$ 1> t ma:'". 

CCtllp.'llllM lt*/V tiQ ) 

tll~\.'l lllM It I.UgQ (I) 

CCtllp.'llllM It H! •JU ih} 

w ttv·v•:ru ;,w';J 

utHetJ•t~ ) 

TCt) 01VUtfDIII f bOI (<If) 

''~'•" U•••gn tt:H" w 

Af,1 BIEIIT COli DrTO liS 

Sj) ~ HMt01.0:..11 i) 

;:OJIIbl!lt:.. . l 0U$ 1t{ .) 

THERMAL PROPERTIES OFCOf.1PARTf.1EIIT Elt::LOS IIIG SURFACES FOR 

ll~lbl liiiU Thnll lll ~ 1tt1 i); pc) 

11~1·)1 lllllg Thnlla iCOid iCUJit{ ;t.) 

11~1·)1 L1111 ~) ~ HMt@ 

11~1·)1 LIUUI OU$l\l ) 

77.00!,. 

0.000 17 .,_.,~m~, 

1.1 .1\Q.M. 

900 p'm' 

110, : . .:. l d~ U It{ W II a lb lll a!J II{ conect WIG . .:.111 bl?l V.ll n 111p~ Iatif~ (r,) lip It 

EXPERIMENTAL THERMAL PROPERTIES FOR COMMON INTERIOR LINING MATERIALS 

'·"' 11.'11 

•:jlC ' c p 

it'lV,tll .. 40 .. ~~c ;I:V'f,III-IG ;t:J.•:o-IG f;<t.tll"' 

.' .ltiiiiUh'l fill~) roo 0.106 OIJ>S 27 10 

S. l (OS._. Callm) 197 0.o5' 0 .165 7850 

I~' 2.9 0.0016 0 .75 2WO 

61•:t: 1.7 ooore •• 2000 

Gl.'li$. Pl.~ 1.6 0.00076 •• 27 10 

61tt .COICI:' 6bct 1.2 0.00073 ... 1roo 

Gy):<$ I h'l 60.'IId 0.18 0.00017 1.1 .,., PI(.,'OCd 0.16 0.00012 zs SlO 

b~l ll $11.1\b l 60.'IId 0.16 0.00053 125 210 

c••:ho."'" 0.15 0.00015 125 ., M l.'l,d COICI:' 0.12 0.00026 ~ 

Pl.'li~JI».'IId 0.12 0.00016 ... "" .., Cai: IUII S llba' 6oar.l o.ore 0.00013 1.12 700 

:..l . ull Ita S llba' U:d; o.coo 0.0001' 1 

Gl.'li$ fb~l l 1.10)1 0.0018 o.oooo:sr •• "" ~pal ~d 0\1$1/I~H 0.001 0.00003, IS "' UHI SI~ III!d ~ EI,I lt ~ El' lt ~ El' lt ~ "' EI,IVa iH 

' , • 0 

II ' Mm 

II ' Mm 

Select Material 

lji,pumaw1 ·I 

Scroll to d~ •I r~d m11 ~ 11a 111H n 

Oick tl~ ~cu n 
J-8

FIRE SPECIFICATIONS 

Fire Heat Release Rate (Q) 1500.00 •:•.:v 

Calt ulate I 

METHOD OF McCAFFREY, QUIIITIERE, AIID HARKLEROAD (MQH) ~'t•~rr:~:SFP H~-..'\ C(F ~Pi'<:~~a:.m ~nc-HN;J i" &Ui ,~. P~~ 17$ . 

Where AT11 = T 11 · T,.= upper layer gastempemure rise abot@ ambient (K) 

Q = heat release r.Jte oflhe fire (kVll) 

A· = area oft@ntilalion opening (m') 

h·: =height of ventilation opening (m) 

~ = convective heat transi!r coefficient (kW.tn :t -K) 

A =total area oflhe compartment enclosing surface boundaries e:mluding area of t@nt openilgs (m:t) 

Area d Ventilation Opening calculaticn "'= (w") (h.,) 

mere A· = area oft@ntilalion opening (m") 

Wv= vent widlh (m) 

h·: = t@nt height (m) 

A· = 1.95 m" 

Thermal Penetration Time Calculation 

tp = (pc.-11<) (6D.i 

Where t 11 =thennal penemion time (sec) 

p = interior construction d ensitv (kAhn 1 c11 = in~rior construction heat capacity(kJA<g-K) 

k =interior constructionthennal conductiWy(kWhn·K) 

6 = int:eriorconSII'\Iction thickness (m) 

1001.90 sec 

Heat Tranifer Coefficient CalcUaticn 

~ = v(kpc.t) fort< ~ or (k/6) fort> tp 

mere = heat11'3nsfercoefficient(kWhn:t·K) 

kpc = int:erDrconSII'\Iction 1hennal inertia (kWhn :t.K):t -sec 

(a thermal property of material responsible forthe me oftempemure rise) 

t =time after ignition (sec) 

See table below for results 

Area d Compartmert ErclosinA Surface Bcun::laries 

A= [2(w )+2(h xw )+2(h xlc)]·A· 

mere A =total area oflhe compartment enclosing surface boundaries e:mluding area of t@nt openilgs (m'') 

w .. = compartment width (m) 

= compartment length (m) 

~ =compartment height (m) 

A· = area oft@ntilalion opening (m") 

A= 299.05 m· 

Ccmpartment Hd Gas Laver TemperatU'e VvUh NatU'al Ventilation 

AT, = 6.85 (Q'I(A(h·,)' ')(A h•)f• 

AT~: = ~: · T,. 

T11 = AT~: + T,. 
J-9

lr!III!IM 

11m~ After 1 ll1on t h, 

~·~~ .) ~ C. A0 14 

' (+.!)0 - 1 " 0.05 

' "' 0.04 

' "' 0.0$ 

• "' 0.0$ 

' "' 0.02 

" "' 0.02 

" "' 0.01 

" 1200 0.01 

" 1500 0.01 

" 1$00 0.01 

" 2 100 0.01 

" 241:+ 0 0.01 

" 2700 0.01 

" $000 0.01 

55 $$00 0.01 

" $~00 0.01 

4T, 

!10 

T, 

.i - ~$.(1(1 

4!1. ~ 54." ~ 

27U 2 577.$2 

~U~ 5~7 $~ 

1U~ ~1U~ 

HU~ uu~ 

$~U1 ~~U1 

$~ 1.50 ~suo 

502.$7 $00.$7 

502.$7 $00.$7 

502.$7 $00.$7 

502.$7 $00.$7 

502.$7 $00.$7 

502.$7 $00.$7 

502.$7 $00.$7 

502.$7 $00.$7 

502.$7 $00.$7 

tbt Gas l.aya' Terrpel3lu-e 

Naur3 \kntilalion (MOH Method) 

T, T, 

"" rF> 

25.00 (7.(1(1 

7J ~ 525.7$ 

$0U 2 5$0.1~$ 

4.$~ ~1UO 

$$M~ Ul.$~ 

$50 ~~ ~U ~ 

$~0 ~1 $5 ~5 

41UO 7$ ~.~~ 

527.$7 ~$ 1.27 

527.$7 ~$ 1.27 

527.$7 ~$ 1.27 

527.$7 ~$ 1.27 

527.$7 ~$ 1.27 

527.$7 ~$ 1.27 

527.$7 ~$ 1.27 

527.$7 ~$ 1.27 

527.$7 ~$ 1.27 

~ 1000 

d88 

1100 1~ .. .---.. ----------------------------------------------1 

~ 700 

• gss 

"'

~ 

~ ~8 100 

0 

0 

ESTIMATING SMOKE LAYER HEIGHT 

METHOD OF Y AMANA AND TANAKA 

z• @:0 t>'JA,) + (lA '" )) • 

10 

V\1 ~ te Z • $111 ~ l. l h • .;J II) 

Q • h a tiHMH Ia' 1U ~ liP. ;_I;V'V) 

t•thH ~I •J• t D• (' c) 

~ COIII P,'11111 ~ •U ~·.;J II) 

.:... - co111pa1111 u tTbol a •e a ~~ j 

t • a co tutgl1~ • by•; • O.rJ16/p;, 

p., • •otg.u l. '" ult{ $9ihl ) 

tgt.r~ • btp JSlfT~> 

T11 • •otga. h\~ ' ' '11 puatu ~ 

CCffl plrtm~ t Ar~a CIICUiaUon 

:.~ • ;, ~ (I) 

~ te A,• C0111pa1111UtTbol a •ea ~~ ') 

cc ll pa lbll ~ •twtn• ~~) 

I • CCtllpalbiiUt h g1i (II) 

A· • $$ ~1 " 

Hot Gat l a','H D;n tl t; O'IICUiaUon 

p"- 353fT~ 

O'llculaUon for COn• t mt K 

20 30 

Time (rrin) 

40 50 60 
J-10

1!1!!1!1 Caution! Tht smokt ltytr l'lti~ is • ccnurvative estimate ardis orly 

intended t o j:rOJidt tn lnd oil: ion whtrt tht h.?t gas layer is located. Calculated 

smd<e ltytr htlgl't bel CHI tl'lt vent heigH: art n.?l: credtatl e s ince the cal cU ation 

is rot aCCOU"'tlng fer t ht smokt ulti rg the vtnt . 

.... •• C.ll,,..llt OO ••t.e t• r erhtltllt ;.c.h •re-r• tllt 

.... UtAII ) tW'M..-:) =• > ,,., • t. U . _ ... ... t:..M 

I .... ..... "' '" ' tAl ... : .. . .. •w 

' .... t . l:t ... •w 

' .... .... -: ... LN 

' ... , ....... : ..... LN 

• .... ..... : . .u LN 

IS .... .... : . .u LN 

,. .... t .IN : . .u LN 

" .... t . 1.7-: : . .u LN 

" .... t . l7-: : . .u t.N 

.. .... t . l1t : . .u t.M 

.. .... t.11t : . .u .... .. .... 0.11: : . .u .... .. '·"" •• 11': : . .u t.OO 

.. ...... 0 . 11': : . .u t.\10 

.. '·"" • • 11': : . .u t.\10 

Smoke l.a}ler Heig.t 

NJLIIII '-'Milation (.Mt1hod of Yarrena and Tanaka) 

14 

€ 12 

r-

~ 10 

! 8 

8 

t • 

2 

0 

0 10 20 30 40 50 

Time (rrin) 

Tl~ oltOit c.:, , oi O"I • t ltOitd 01\ 1•111-.:••trl II' llt OI~td h lilt OJ PE M4Nibo ot, Clff h 

P•o trc l on &vlnrtlll'tl,) .. ll on,.:oo:, 

C atG.Ibi OI'II • t ltOitll OnCtlbh OIH•n ttbl\1 011\I:J 1\.Wt lrllt"l\lllll>lbl cnl, Tilt" iP.' Il ClfU.t:h 

CatC, , IIbnl 111 1111)' 01 1111111)' r.Qo!l'*'t lfOIOI'IIII•It l'l"ll(t;t .:ll U i!l atlnn l lh,o l cn,<lil"o!! lh:>' 'l 

0 1'41 Itt '""'l•lt !I'll .. , tnll'lbllltll u:t ' · 

Joi i iOI.Whte::hc • et.Q i onln h t l l>lfOII•\tt ''* l•u n~ttll ll 1111 h •• ' " "' t CII'Ninll ;:~:~Ja cn, 

IUit III'ICIOII.Ot.lll' t \OGflll't 01( h; -.:cYOCJ Of lilt a >' ON. 

M r ..... tiCN ,C:Oito"'tni!,C:Or'ICUI'II , OII'ItiWtU I.Ool btti'OI l en tiiOI(I) In he :a>ltacil hetl. 

~~>•a uf\11 Gflt"'• bn••"c••· 

.,. 

lltOI : :&lOt: IE It Ei'lfii OOit VEi f 

lltOI : :.tOt. E ll Edtii OOU YIE"11 t 

lltOI : :&lOt. E ll Edfii GOU Vh f 

lltOI : WOt.EII Ellfii GOU Vflll 

t'TJOI : SUOU:II IEJnii GOU YU t 

WUOI : SIIOtiEit Einti OOit V£1 1 

t'UOI : SIIOiiEit Einti OOit V£1 1 

ntol : SIIOiiEit Einti OOU YEi t 

II'UOI : SIIOtiEit E:tnti OOit VEat 

WUOI : $UOiiEI$ E:1n 11 0011 VIEi t 

.-1101 : $UO,UI$ E:tnii 60•t VEil 

.-1.01 : $UOJiE I$ E:tnii 60•t VEi l 

VTIOI : $UOkE U E:tiTU 60tn VEil 

UTIO I : OJiEI $ E:tiTI I OOUf V£1 l 

UTIO I : Ot>EI $ E:tiTI I OOU f V£1 l 

UTIO I : I:UOkE I ~ E:<ITII OOU f VEl l 

co. 

= 

c.o. 

c.o. 

c.o. 

c.o. 

80 
J-11

Problem 2: Compartment Fire with Forced Ventilation

Problem J-2

Problem Statement

Consider a compartment 12.0 m wide x 12.0 m long x 3.7 m high (40.0 ft wide x 40.0 ft long x 12.0 ft

high) c c c (w x l x h ) with a forced ventilation rate of 3.78 m /s (8,000 cfm). Calculate the hot gas layer 3

temperature in the compartment for a fire size of 2,000 kW (1,896 Btu/sec) at 5 minutes after

ignition, assuming that the compartment boundaries are made of 5.10 cm (2.0 in) thick gypsum

board.

Solution

Purpose:

g

(1) Determine the hot gas temperature in the compartment (T ) at t = 5 min after ignition.

Assumptions:

(1) Air properties (ambient) are at 25 °C (77 °F).

(2) The ceiling is unconfined, unobstructed, and flat.

(3) The heat flow through the compartment boundaries is one-dimensional.

(4) The heat release rate (HRR) is constant.

(5) The fire is located at the center of the compartment or away from the walls.

(6) The compartment is open to the outside at the inlet (pressure =1 atm).

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 02.2_Temperature_FV.xls
J-12

FDT Input Parameters: s

Enter the following parameters in both spreadsheets (values only):

c

- Compartment Width (w ) = 40 ft

c

- Compartment Length (l ) = 40 ft

c

- Compartment Height (h ) = 12 ft

- Interior Lining Thickness (*) = 2 in

- Select Material: select Gypsum Board from the combo box

- Compartment Ventilation Rate = 8,000 cfm

- Fire Heat Release Rate = 2,000 kW

Note: When Gypsum Board is selected, its thermal properties are automatically

selected from the table and entered in the corresponding input cells.

Results

From the table of results of the spreadsheet at t = 5 minutes after ignition we obtain:

Ho gt Gas Layer Temperature* T °C (°F) 

Method of Foot, Pagni, and

Alvares (FPA)

Method of Deal & Beyler

203 (398) 244 (471)

 *spreadsheet calculations attached on next page
J-13

Spreadsheet Calculations

FDT2: 02.2_Temperature_FV.xls

CHAPTER 2. PREDICTING HOT GAS LAYER TEMPERATURE IN A ROOM 

FIRE WITH FORCED VENTILATION 

COMPARTMENT WITH THERMALLY THICK!THIN BOUNDARIES 

Version 1805.0 

The following calcol31ions estimate the hot gas layertemper.rure and smolollayer height in enclosure ire. 

Parameters in YELLOW CELLS are Entered by the User. 

Parameters in GREEN CELLS are ALiomatically Selected from the DROP DOWN M ENUforthe Material Selected . 

.All subsequent output wlues are calculated bythe spreadsheet and based on wlues specified in the input 

parameters. This spreadsheet is pr~cted and secure to avoid errors due to a wrong entry in a cell(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

COMPARTMENT INFORMATION 

Compartment VlAdth (w .. ) 

Compartment Length 0.) 

Compartment Height (h.) 

Interior Uning Thickness (6) 

AMBIENT CONDITIONS 

.Anb ient Ptr Temper abJ re (T,,) 

Speci1ic Heat of .Air (c.,) 

.Anb ient J:ir Density ( P,) 

THERMAL PROPERTIES 0 F COM PA RTM E NT ENCLOSING SURFACES 

40DO 1t 

40DO 1t 

12DO 1t 

nool·• 

f------:1,.,0~0 ""% 

1.18 "9111 

Interior UninQ Thermal Inertia (kpc) 0.18 \t iV fll c 

Interior Uning Thermal ConductiWy(k) 0.00017 •:I.N.t!1 4< 

Interior Uning Specific Heat(c) 1.1 t:J.tg-K 

Interior Uning Oensity(p) 960 t<llll 

Note: ~r density will autom<nic:a lly correct w ilh .Anbient ~r Temperature (T ,,) Input 

lHERMAL PROPERTIES FOR COivlviOIIIIITERIOR LIIIIIIG MATERIALS 

Material kf'C k c p 

(kVll.tn:t ·Kf -sec <I<Whn·Kl l<i<Jol<a·Kl (kg An' ) 

12.19 111 

12.19 Ill 

3.60 IJI 

25.00 ~ 

2re.OO K 

Select Material 

I !lle;un Board ·I 

.Aiu minum (pure) 500 0.206 OS95 2710 Scroll to desired material t hen 

Steel (0.5" Carbon) 197 0.054 0.465 7850 Click on select ion 

Concrete 29 0.0016 0.75 2400 

Brick 1.7 0.0008 OS 2600 

Glass, Plate 16 0.00076 OS 2710 

Brick/Concrete Block 12 0.00073 OS4 1900 

Gypsum Board 0.18 0.00017 1.1 960 

Plywood 0.16 0.00012 25 540 

Fiber Insulation Board 0.16 0.00053 125 240 

Chipboard 0.15 0.00015 125 800 

.Aemed Conctet»l 0.12 0.00026 096 500 

Plasterboard 0.12 0.00016 OS4 950 

Calcium Silicate Board 0098 0.00013 1.12 700 

.Aiu mina Silicate Block 0036 0.00014 I 260 

Gla s:s Fiber hsul<nion 00018 0.000037 OS 60 

&:pan ded Polysrve ne 0001 0.000034 15 20 

User Soecified \l.ilue Emr\l.ilue Enter \l.ilue Enter \l.ilue Emr\l.ilue .. . .. 0 . .. 
J-14

COMPARTMENT MASS VENTILATION FLOW RATE 

Forced Ventilation Flow RaW (m) 

FIRE SPECIFICATIONS 

8000 DO !cn11 

Fire Heat Release Rate (Q) 200000 •:tl>) 

I Calculate I 

METHOD OF FOOTE, PAGNI, AND ALVARES (FPA) 

RHH! •o:: :pE "iar.dOO~ .:1 ,: i.'l" 'V~UU l.:.,; ...,-,•,:g, J " Edltb•. 2002, Pag; J-177 . 

Where lL ToJ = T oJ. T ~= upper layer gas temperature rise above ambient (K) 

T~= ambient air temperature (K) 

Q = heat releaser ate ofthe fire (kW) 

m = compartment mass ventilation flow rate (k9"sec) 

C\> =specific heat of air (kJA<g·K) 

tt: = convective heat transfer coefficient (kW/m .:·K) 

Ar= total area of the compartment enclosing surface boundaries (m') 

Thermal PEnetration Time Calculation 

~ = (PcoJk)(6iZ/ 

Where 

~= 

\. = thermal penetration time (sec) 

p =interior construction density (kg/m ~ 

C\> = interior construction heat capaci~ (kJA<g-l-9 

k =interior construction thermal conductivity(kW/m-1-9 

0 = in~rior construction thickness (m) 

4007.63 sec 

Heal: Trcnsfa- Coefficient Calculation 

1\: = v(kPclt) for t < \. or (k/0) fort> \. 

Where 1\: = heattr ansfer coefficient(kW/mz·l-9 

kpc = in~rior construction thermal inertia (kW/mz-K)z·s ec 

(a thermal property of material responsible for the rate oftemperab.ue rise) 

t= time after ignition (sec) 

See table below for results 

Area of Co mpa"t ment En dosing Surface Bound~ies 

Ar= 2 (We X l:) + 2 (heX IA0 + 2 (heX l:) 

Where Ar= total area of the compartment enclosing surface boundaries (m') 

lilA:= compartment width (m) 

l: = compartment length (m) 

h.:= compartment height (m) 

k =area of ventilation opening (m') 

Ar= 475.66 m.: 

Compartment Hot Gas layer Tempa-ature With Force:! Ventilation 

lL ToJIT~ = 0.63(0/ma. To)v.r.:(l't:Alima. )" ·,_, 

lLToJ = ToJ· T~ 

ToJ = lLToJ+ T~ 

3 .776 111 A: c 

U 72t<MC 
J-15

Time After nition t h, AT.,IT0 •r. T. T. T. 

(min) (sec) (kWAn' ·K) (K) (K) ('1:) r•n 

0 0 298.00 2500 7700 

1 " 0.05 045 13334 431.34 158.34 317.01 

2 '" 0.04 051 151 OS 449.0S 17S.OS 348.90 

3 '" O.o3 055 1S2A9 480.49 187.49 3S9.49 

4 '" O.o3 057 171 .13 489.13 19S.13 385.04 

5 "' 0.02 oso 178.14 47S.14 203.14 397.SS 

10 '" 0.02 0£8 20182 499.82 22S.82 440.27 

15 "' 0.01 0.73 217.10 515.10 242.10 487.77 

20 1200 0.01 0.77 228£4 52S.S4 253.S4 488.54 

25 1500 0.01 080 23801 53S.01 2S3.01 505.41 

30 1$00 0.01 083 24595 543.95 270.95 519.70 

35 2 100 0.01 085 25287 550.87 277.87 532.1S 

40 '"' 0.01 087 25902 557.02 284.02 543.23 

45 2700 0.01 089 2S457 5S2.57 289.57 553.22 

50 $000 0.01 090 2S9S3 5S7.S3 294.63 5S2.34 

55 $$00 0.01 092 27430 572.30 299.30 570.74 

so $~00 0.01 093 278£3 57S.S3 303.S3 578.53 

Hot Gas Layer Temperature 

Forced Ventilation· FPAMethod 

700 

~600 ~ 

t..-500 

• ]400 

• Gi300 

~ 

.!"'" 

~200 

~100 

0 

0 10 20 3J 4) &l 60 

Time (min) 
J-16

M ETHOO 0 F OEAL ANO BEY LE R "-"",..,"" :;t-N:i'i..,...,«.tolhi'O~""'-"t.'IIJ""O'I'II :t"bl"'"' llllttl ~~~:I-' I'll 

tt: at Tl'\'ln • rer co~ me l$nt Cal culaUon 

•·· 0.4 vt:pc /l 'btt<1, 

~~~ • • • ~at baU'I!I OO~m l!•t :ltV IIl _.~ 

•:fC• •~tbtco utu tm ~n11a1 hl11'1 ;J;Ir\lfln .. -1\l .. ~~c 

\'11Hnllalptct:.e ltyOflll ~U'III "b. DI1U I~ fblll~lat. te Ita) ; •U I:t;H $$0H,Ibthl•<l fll) 

•• • 0.022 t \N/hf'-K 

Aru compartn~nt Blclollllfl sumu Bomdal1$ t 

A•• Z;,.W<X 1) + 2(. <X W) + 2(. •X I) 

A•- Jl ~~ m·· 

1.<\!Ht~ · T11 - · 11:1)$1 h" ~ tga. 'mpuatm na .. )W$ 111b~ •t (~ 

· <rllbiHtall'•lll:o; otm (I<} 

Q • •$at 1! •aa I~ 011U Ill! t;V\1) 

m- o:tllpaltllutmaa vut1.10,. 1ttN "'' ;_t;ghO) 

p~ t HatoTal ;J:JMJ-1<} 

•· · co•u$CUJ$ ~atto n:t coe m:t •t;t:t/V,tll .. -1<} 

,:.,, . btllal!<t011U O:tll~'<ti111UtU l$ 119 HID:!? bOU d,'lll!$ fl j 

llm$ After tniUon 

"· 

•T, T, T, 

" .... ;t;t/V,fll .. 4ll "" "" """ ' ' - - ~$.0(1 25.0(1 

I " 0.02 IU.23 4$2.23 153.23 

' '" (1.1)2 1~8 3(! J~~.3(! 13$.3(! 

' "' &.&1 uu7 J8U7 15.~7 

4 

'"' &.&1 2&U5 5&4.55 2$1.55 

' "' &.&1 2 18.33 5 1~.33 24$.33 

" "' &.&I 257.Jl 555.47 2$2.Jl 

" "' &.&1 273.2 1 577.2 1 $(!4, 2 1 

" 12&& (!,(!(! 23U& 532.&& $13.&& 

" IS&& (!,(!(! $&5.&$ ~(!$.(!$ $$(!,(!$ 

" 1$(!(! (!,(!(! $ 1$.('2 ~ 11.72 $$$.(2 

" 2 I&& (!,(!(! $2&.$2 ~1M2 $45.$2 

•• lJI)(! (!,(!(! HU3 .73 $5 1.(3 

., 27&& (!,(!(! $$1.3(! U& $5U& 

" $(!(!(! (!,(!(! $$US UJ.$5 $~1.$5 

55 $$(!(! (!,(!(! UIJ.lf U$.27 $~5. 27 

" $~(!(! (!,(!(! UHf Ul.?'f $~$.('( 

Hot Gil • ll ~m p~r111Ur~ 

f OIO?d VUUk11t.ll - ~ai<U d 6~ l: I Ui l 

800 

700 

;;: QOO 

'-' 

2: 500 ,.. ~ , 00 

E i' 300 

,:!: :oo 

100 

0 

0 10 , 30 .. so 

n~ '1J'I II} 

T, 

77 "' ,(1(1 

$1$.71 

$8 1.&2 

42&.2 1 

JJ$.73 

J( 1.1$ 

SJU5 

573.57 ~&~ (! 

&~ 

U1.7& 

~SJ J3 

~~5 22 

7 4.42 ~$2.4$ 

~$U3 

~35.73 

•• 
J-17

Summarvof ResUt 

800 

Hd Gas Layer Temperature 

F' orced Ventilation 

700 

600 

~ 

t... 500 

~ 400 

/...::-~~~~~ f 300 ~ 

200 

IOO l---------------------------------------------1 

0 

0 10 

MJUIIM 

20 30 

Time (min) 

40 50 

The above calcolalionsare based on pinciples de'Wioped in1he SF'PE Haldbookof Fire A-otection 

&IQineerinQ, 3"' Ei::lition, 2002. 

C-'cutnims are based on certan assurrptDns ard have irherentlimitJ!ions. The results of such 

cabulalims may or may rot ha'W reasonaHe p-edictiw capabihies for a gi'Wn situalim, and should 

onlybe interpreted byal ilfonned user. 

Plthough each calcdalion in the spreadshec has been wi1ied with the results ofhand c-'cdatDn, 

thEre is no absolute guarartee oflhe accU'3cyoflhese calcolalions. 

Alyquestims,corrments, concerns. ard suggestions, orto rEPOrt an error(s) in1he spreadsheet, 

please send 3l emal to nxi@Jlro.govormxs3@:flro.gw. 

60 

--IP ~h:-:1 

0~ ~ '*YIHU,I'Q:I 
J-18

Problem 3: Compartment Fire with Multiple Vents

Problem J-3

Problem Statement

Consider a compartment 4.6 m wide x 4.9 m long x 3.0 m high (15 ft wide x 16 ft long x 10 ft high)

with multiple vents and 15.24 cm (6 in.) of gypsum board as interior boundary material.

The compartment has two vents of 0.6 m wide x 0.6 m high (2 ft wide x 2 ft high) and one vent of

1.2 m wide x 2.1 m high (4 ft wide x 7 ft high), all located on the same wall. The top of the highest

vent is at 2.4 m (8 ft) above the floor. If the ventilation system is not operating (natural ventilation)

and at 10 minutes after a fire ignition the hot gas layer temperature reaches the failure temperature

o g g f the IEEE-383 unqualified cable [assume T = 218 °C (T = 425 °F) as failure for this example],

what minimum HRR might cause this failure? Is the smoke exiting the compartment at the time of

cable failure?

Consider the same compartment with a mechanical ventilation rate of 0.236 m /s (500 cfm) and a 3

fire with an intensity equal to the HRR of the natural ventilation scenario. What would be the hot gas

layer temperature around the cable trays at 10 minutes after ignition? (Use method of FPA and

method of Deal & Beyler). What is the effect of the ventilation system on the hot gas layer

temperature? Compare the results of the forced ventilation scenario as a function of time after

ignition and explain the discrepancy between methods.

Solution

Purpose:

(1) Determine the minimum HRR that could cause the IEEE-383 unqualified cable failure

at 10 min after ignition in a natural ventilation scenario.

(2) Determine if the smoke is exiting the compartment at 10 min after ignition.

g

(3) Determine the hot gas layer temperature (T ) at 10 min after ignition if the mechanical

ventilation system is activated and the HRR is equal to the HRR of the natural

ventilation scenario (i.e., use the answer of purpose 1).

(4) Evaluate the effect of the ventilation system in the hot gas layer temperature (i.e.,

increase, decrease, etc.).

(5) Analyze the discrepancy between the methods of FPA and Deal & Beyler, and mention

possible causes of that discrepancy.
J-19

Assumptions:

(1) Air properties (ambient) are at 25 °C (77 °F).

(2) The ceiling is unconfined, unobstructed and flat.

(3) The heat flow through the compartment boundaries is one-dimensional.

(4) The HRR is constant.

(5) The fire is located at the center of the compartment or away from the walls.

(6) The compartment is open to the outside at the inlet (pressure = 1 atm).

Pre FDT Calculations: s

Equivalent Vent

Since the FDT are designed to calculate the hot gas layer temperature and smoke layer s

height based in only one vent compartment, we need to calculate an equivalent vent that

represents the three vent openings.

Vent Opening Characteristics

W vidth w

(ft)

He vight h

(ft)

A ore A

(ft )

2

MQH o Factor A

(ft )

5/2

2 2 4 5.66

2 2 4 5.66

4 7 28 74.08

Total 36 84.4

The equivalent vent dimensions must satisfy the following conditions in order to have the

same effect of the actual multiple vents:

Cond o v vition 1: A = 85.4 ft Condition 2: w x h = 36 ft 5/2 2

36 v ft = 85.4 ft w x 5.63 ft = 36 ft 2 5/2 2

hv v = 5.63 ft = 5.6 ft w = 6.39 ft = 6.4 ft

Spreadsheet (FDT ) Solution Procedure: s

Natural Ventilation Scenario

Use the following FDT :

s

(a) 02.1_Temperature_NV.xls
J-20

FDT Input Parameters: s

Enter the following parameters in the spreadsheet (values only):

c

- Compartment Width (w ) = 15 ft

c

- Compartment Length (l ) = 16 ft

c

- Compartment Height (h ) = 10 ft

v

- Vent Width (w ) = 6.4 ft

v

- Vent Height (h ) = 5.6 ft

T

- Top of Vent from Floor (V ) = 8 ft

- Interior Lining Thickness (*) = 6 in

- Select Material: select Gypsum Board from the combo box

- Fire Heat Release Rate = 410 kW*

Note: When Gypsum Board is selected, its thermal properties are automatically

selected from the table and entered in the corresponding input cells.

*The HRR value is a starting value for the trial and error procedure explained below.

Because we are looking for an HRR value that could generate a hot gas layer temperature

of 218 °C (425 °F), we need to enter HRR values on the spreadsheet until get a

temperature close to 218 °C (425 °F) at 10 min after ignition. This trial and error procedure

is shown in the following table.

Trial and error procedure to determine the HRR

Ta grget: T = 425 °F for natural ventilation scenario

Trial Heat Release Rate

(kW)

Ho gt Gas Layer Temperature (T )

at 10 min after Ignition (°C) (°F)

1 100 100 (213)

2 200 145 (293)

3 300 182 (360)

4 400 215 (420)

5* 410 219 (425)

*spreadsheet calculations attached on next page for last trial at t = 10 min

Results

According to the method of McCaffrey, Quintiere, and Harkleroad (MQH), an HRR of approximate

410 kW could generate a hot gas layer temperature of 218 °C (425 °F) at 10 minutes after ignition.

But, what is important for practical purposes is that for the given compartment and ventilation

conditions, a fire power of about 400 kW (379 Btu/sec) may generate a hot gas layer temperature

of 204+°C (400+°F). Also, the smoke layer height at 10 minutes after ignition is approximately z

= 0.39 m (1.27 ft), based on the method of Yamana and Tanaka. That means that the smoke could

be T exiting the compartment because z is less than the height of the vent top (V ).
J-21

Spreadsheet Calculations

FDT : 02.1_Temperature_NV.xls (Temperature_NV Thermally Thick)

s

CHAPTER 2. PREDICTIIIG HOT GAS LAYER TEMPERA lURE AIID SMOKE 

LAVER HEIGHT Ill A ROOM FIRE WITH IIA lURAL VEIITILATIOII 

COMPARTMEIITWITH THERMALLY THICK/THIII BOUIIDARIES 

Version 19l5D 

~ 'bt)Witg ca• • h1J' " 011ate 1u •otg.u tr l,mpuatue <Ud ~ tr ••~ t~•t • u c•x •.: 111e. P.'ll'\'lffi$'rl In YEllOWCEllS llr$ Blter$d 11,' Ul$ UtH . 

P.'ll'\'lffi$'U In GREEII C EllS llr$ AUtomllU~II IV $$1$C'd TCffl 1l$ DROP OOWII t.1EIIU br1ll$ f.btel1ill h i$C,d . 

. O:..II bHq tt 1> tt •• ' <ue ca t:tl.~ by ~ P'~a:t> ~~ta d baad lt ' $pecrtd 11 1u ltptt j).'II.'IIIH' IL n a; $ple<t:I$•Ht ~ p1o-.~d <tHI$eCue bat.tot le IDI> (ft e b a WIOt ge 11r>{ II a 0:11('). 

n e c•ap' Jlt1U tiUR~ ' •o• t1 be JMdbe'bte at a~<lll$ 1> t ma:'". 

CCtllp.'llllM lt*/V tiQ ) 

tll~\.'l lllM It I.UgQ (I) 

CCtllp.'llllM It H! •JU ih} 

w ttv·v•:ru ;,w';J 

utHetJ•t~ ) 

TCt) 01VUtfDIII f bOI (<If) 

''~'•" U•••gn tt:H" w 

Af,1 BIEIIT COli DrTO liS 

Sj) ~ HMt01.0:..11 i) 

;:OJIIbl!lt:.. . l 0U$ 1t{ .) 

THERMAL PROPERTIES OFCOf.1PARTf.1EIIT El t::LOS IIIG SURFACES FOR 

II~ fbi LIIIU Thnll lll ~ lttl i); pc) 

11~1·)1 Lllllg Thnlla iCOid iCUJit{ ;t.) 

11~1·)1 L1111 ~) ~ HMt@ 

11~1·)1 LIUUI OU$l\l ) 

77.00!,. 

0.000 17 .,_.,~m~, 

1.1 .1\Q.M. 

900 p'm' 

110, : . .:. l d~ U It{ W II a lb lll a!J II{ conect WIG . .:.111 bl?l V.ll n 111p~ Iatif~ (r,) lip It 

EXPERIMENTAL THERMAL PROPERTIES FOR COMMON INTERIOR LINING MATERIALS 

'·"' 11.'11 

•:jlC ' c p 

it'lV,tll .. 40 .. ~~c ;I:V'f,III-IG ;t:J.•:o-IG f;<t.tll"' 

.' .ltiiiiUh'l fill~) roo 0.106 OIJ>S 27 10 

S. l (OS._. Callm) 197 0.o5' 0 .165 7850 

I~' 2.9 0.0016 0 .75 2!00 

61•:t: 1.7 ooore •• 2000 

Gl.'li$. Pl.~ 1.6 0.00076 •• 27 10 

61tt .COICI:' 6bct 1.2 0.00073 ... 1roo 

Gy):<$ I h'l 60.'IId 0.18 0.00017 1.1 .,., PI(.,'OCd 0.16 0.00012 zs SlO 

b~l ll $11.1\b l 60.'IId 0.16 0.00053 125 210 

c••:ho."'" 0.15 0.00015 125 ., M l.'l,d COICI:' 0.12 0.00026 ~ 

Pl.'li~JI».'IId 0.12 0.00016 ... "" .., Cai: IUII S llba' 6oar.l o.ore 0.00013 1.12 700 

:..l . ull Ita S llba' U:d; o.coo 0.0001' 1 

Gl.'li$ fb~l l 1.10)1 0.0018 o.oooo:sr •• "" ~pal ~d 0\1$1/I~H 0.001 0.00003, IS "' UHI SI~ M!d ~ EI,I lt ~ El' lt ~ El' lt ~ "' EI,IVa iH 

' , • 0 

.,,. "' ' fl/fm 

Select Material 

lji,pumaw1 ·I 

Scroll to d~ •I r~d m11 ~ 11a 111H n 

Oick tl~ ~cu n 
J-22

FIRE SPECIFICATIONS 

Fire Heat Release Rate (Q) 410.00 •:•.:v 

Calt ulate I 

METHOD OF McCAFFREY, QUIIITIERE, AIID HARKLEROAD (MQH) ~'t•~rr:~:SFP H~-..'\ C(F ~Pi'<:~~a:.m ~nc-HN;J i" &Ui ,~. P~~ 17$ . 

Where AT11 = T 11 · T,.= upper layer gastempemure rise abot@ ambient (K) 

Q = heat release r.Jte oflhe fire (kVll) 

A· = area oft@ntilalion opening (m') 

h·: =height of ventilation opening (m) 

~ = convective heat transi!r coefficient (kW.tn :t -K) 

A =total area oflhe compartment enclosing surface boundaries e:mluding area of t@nt openilgs (m:t) 

Area d Ventilation Opening calculaticn "'= (w") (h.,) 

mere A· = area oft@ntilalion opening (m") 

Wv= vent widlh (m) 

h·: = t@nt height (m) 

A· = 3.33m" 

Thermal Penetration Time Calculation 

tp = (pc.-11<) (6D.i 

Where t 11 =thennal penemion time (sec) 

p = interior construction d ensitv (kAhn 1 c11 = in~rior construction heat capacity(kJA<g-K) 

k =interior constructionthennal conductiWy(kWhn·K) 

6 = int:eriorconSII'\Iction thickness (m) 

36068.24 sec 

Heat Tranifer Coefficient CalcUaticn 

~ = v(kpc.t) fort< ~ or (k/6) fort> tp 

mere = heat11'3nsfercoefficient(kWhn:t·K) 

kpc = int:erDrconSII'\Iction 1hennal inertia (kWhn :t.K):t -sec 

(a thermal property of material responsible forthe me oftempemure rise) 

t =time after ignition (sec) 

See table below for results 

Area d Compartmert ErclosinA Surface Bcun::laries 

A= [2(w )+2(h xw )+2(h xlc)]·A· 

mere A =total area oflhe compartment enclosing surface boundaries e:mluding area of t@nt openilgs (m'') 

w .. = compartment width (m) 

= compartment length (m) 

~ =compartment height (m) 

A· = area oft@ntilalion opening (m") 

A= 98.86 m· 

Ccmpartment Hd Gas Laver TemperatU'e VvUh NatU'al Ventilation 

AT, = 6.85 (Q'I(A(h·,)' ')(A h•)f• 

AT~: = ~: · T,. 

T11 = AT~: + T,. 
J-23

r;meAHer h, ~;; ~ (~ ) . (n;n) (sec) 

-Ws 

-Wo ~ 

I 

-m 

248 

260 I 

Hot Gas Layer Temperature 

Natural Ventilation (MOH Method) 

I 

2859 

~500 

~400 600 ~ ~~===:::~~ ~3oo ;;; HF~--------------------------------------------------~ 

~200 u-------------------------------------------------------------1 ~ 

~ 100 1-----------------------------------------------------------~ 

0 10 20 30 

Time(min) 

40 60 
J-24

ESTIMATING SMOKE LAVER HEIGHT 

METHOD OF YAMA. AA DT AKA 

:- p .o {1 rl » WH If : .. Ulld .t 1.\<ttlt!Jit .. ) 

0 •ltilltltltlm till. OfUt 111! f W) 

t • Uat l!'t I 1)1 UU (1-tC) 

I • OOIIIp)llllf tU U)U fl) 

A • CII*piWllltttfOOUtt.Jfil') 

l • ill CO. U:u t g t't t DVI. .. O.CI"6fp 

p • l ot9)1 ~11 CifU ~f9'- ) 

r bt r ~ 

T - I OC9<)1 D,tl tllpt._lt (tJ 

c:a.p~~tnUrta OkUbiOn 

... - (O')(Q 

W M il A ~u i>Of •afl") 

W .. CCMp.l ... 11WI:at fl) 

I .. CCftlp.lllriM t1h !JI .. ) 

A,_ .. 21.Jt M 

H<ltGi t ltltf Otn tl \' O ltUiliiOn 

, - ...,. 

Cl'ltt u111 110n rorOOnt tlnt l'i 

k - 0/116/p 

Smol!t Gil' U vtr Ht l,lllfW 1l 11 \tl'lU 11 n 

: - (•'::1.0 f.\1\) + ( 111 ) 

Jlll!llll Caution! The m::~ke l ayw height i s • oo servat ~ estimate and is only 

intended to pro-..ide ., lndiCIIIon W'lere the hot gas layer is locaed. Calc:ulcted 

smo Ice I ayer hli ght bll ow the \.9'11. height are not c redit able si roe the calculati en 

is net aooountlng for the smo ke e dting the 'M"It. 

nmt l o Com tnnt!lll l!t Laver t smoh Laverlu ltlllt 

Ill ' ) iJ:i)lll ) .. w .... ,. Z {II) zn 

--.-.. '" .. 3.0$ 10 ,!)(1 

1 o.n O.OU 2.44 3.\)!) 

2 o.n O.OH 2.44 3.\)!) 

3 0.11 0.031 2.44 $.!)!) 

4 0." 0. 100 2.44 8.00 

s O.TS 0. 10 I '·" 8.00 

"' '·" 8.1)1) 15 0.10 O. IU 

'·" 8.00 

20 o.u 0. 111 

'·" 8.00 

" U 1 O. IIS 

'·" 8.00 

" U1 0.1U 

'·" 8.00 

" '·" t .1U 

'·" .... .. us t.1t7 

'·" .... -.:u .... '·" Ui 

.. t .U t .ln .... LN 

.. t .U t .IU .... LN 

.. us t .IU .... LN 

CA Ult:)Jt SMOKE IS EXrTIIIG OUTVIHIT 

UTI:)fl: Sf.10KE IS EXrTIIIG OUTVEIIT 

UTI:.tt Sf.10KE IS EXrTIIIG OUTVEIIT 

UTI:.tt ti.10KE IS EXrTIIIG OUTVEIIT 

UTI:)fl: ti.10KE IS EXrTIIIG OUTVEIIT 

UTI:)fl: SI.10KE IS EXrTIIIG OUTVEIIT 

UTI:)fl: SI.10KE It EXrTIUG OUT VEUT 

UTI:)U: SI.10KE It EXrTIUG OUTVEUT 

UTI:>It U.10KE IS EXITIUG OUTVEUT 

UTI:>It UIOKE IS EKITIUG OUTVEUT 

UTI) It $YOKE IS EXITIItG OUT VEUT 

UTOJt: SUOt<f J$ El iTIItG OUTVEUT 

UTI)tt SltiC*f It El fTIUG OUT VfJIT 

UTI)tt UIOKf It fllfltG OUTVfUT 

UTI)tt UIOKf It f l RlltG OUTVfUT 

UTI)tt UIOKf It f l lfltG OVTVfJIT 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

leA 

leA 

leA 

b 

b 

co 
J-25

Smoke Layer Height 

Natural Ventilation (Method of Yam ana and Tanaka) 

12 

~ 10 0 

~ 8 u. 

E 6 0 

.. 

l:' 4 

"' ·;;; 2 

J: 

0 

0 10 20 30 40 

Time (min) 

The abo\@ calculations are based on principles de\@loped in 1he SFPE Handbook of Fire 

Protection Blgineering, 3"' 6:1ition. 2002. 

50 

Calculations are based on cenain assumptions and ha\@ inherent limitations. The results of such 

calculations mayor maynot ha\@ reasonable predicti\@ capabilities for a given situation, and should 

only be interpreted by an infonned user. 

Plthough each calculation in 1he spreadsheet has been \@riied with the results of hand calculation, 

there is no absolute guarantee ofthe accuracyofthese calcub1ions. 

~yquestions, comments, concerns, and suggestions, or to repon an error(s) in 1he spreadsheet, 

please send an email to nxi@lroQOV. 

60 
J-26

Spreadsheet (FDT ) Solution Procedure: s

Forced Ventilation Scenario

Use the following FDT :

s

(a) 02.2_Temperature_FV.xls

FDT Input Parameters: s

Enter the following parameters in both spreadsheets (values only):

c

- Compartment Width (w ) = 15 ft

c

- Compartment Length (l ) = 16 ft

c

- Compartment Height (h ) = 10 ft

- Interior Lining Thickness (*) = 6 in

- Material: select Gypsum Board from the combo box

- Compartment Ventilation Rate = 500 cfm

- Fire Heat Release Rate = 410 kW

Note: When Gypsum Board is selected, its thermal properties are automatically

selected from the table and entered in the corresponding input cells.

Results

From the table of results of the spreadsheet at t = 10 minutes after ignition we obtain:

Ho gt Gas Layer Temperature* T °C (°F) 

Method of Foot, Pagni, and

Alvares (FPA)

Method of Deal & Beyler

329 (625) 440 (824)

*spreadsheet calculations attached on next page

These results demonstrate that the ventilation system is able to increase the hot gas layer

temperature. That is, for a specific compartment and heat release rate, the ventilation

system can drastically increase the hot gas layer temperature due to the oxygen supply.
J-27

Spreadsheet Calculations

FDT : 02.2_Temperature_FV.xls s

CHAPTER 2. PREDICTING HOT GAS LAYER TEMPERATURE IN A ROOM 

FIRE WITH FORCED VENTILATION 

COMPARTMENT WITH THERMALLY THICK!THIN BOUNDARIES 

Version 1805.0 

The following calcol31ions estimate the hot gas layertemper.rure and smolollayer height in enclosure ire. 

Parameters in YELLOW CELLS are Entered by the User. 

Parameters in GREEN CELLS are ALiomatically Selected from the DROP DOWN M ENUforthe Material Selected . 

.All subsequent output wlues are calculated bythe spreadsheet and based on wlues specified in the input 

parameters. This spreadsheet is protected and secure w avoid errors due to a wrong entry in a cell(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

COMPARTMENT INFORMATION 

Compartment VlAdth (w ) 

Compartment Length 0.) 

Compartment Height (h.) 

Interior Uning Thickness (6) 

AMBIENT CONDITIONS 

.Pmb ient Ptr Temper atiJ re (T ,.) 

Speci1ic Heat of ~r (c11) 

.Anb ient Ptr Density ( P,) 

THERMAL PROPERTIES 0 F COM PA RTM E NT ENCLOSING SURFACES 

Interior UninQ Thermal Inertia (kpc) 

Interior Uning Thermal ConductiWy(k) 

Interior Uning Specific Heat(c) 

Interior Uning Oensity(p) 

~Note:~~~~ 

15DO 1t 

16DO 1t 

1 ODO 1t 

nool·• 

1----..:1.::0'::10 I:J.t;g-1< 

1.18 t;gfll 

1.57 m 

, .... J.OS IJI 

0.15:4 Ill 

25.00 ~ 

2re.OO K 
J-28

COMPARTMENT MASS VENTILATION FLOW RATE 

Forced Ventilation Flow RaW (m) 

FIRE SPECIFICATIONS 

&~ooolcn .. 

Fire Heat Release Rate (Q) 41000 •:tl>) 

I Calculate I 

METHOD OF FOOTE, PAGNI, AND ALVARES (FPA) 

RHH! •o:: S,:PE "iar.dOO~ .:1 ,: i.'l" 'O~UU~ Ecg l.:.,;...,-,•,:g, J"" Edltb •. 2002, Pag; J-177 . 

Where lL ToJ = T oJ. T ~= upper layer gas temperature rise above ambient (K) 

T~= ambient air temperature (K) 

Q = heat releaser ate ofthe fire (kW) 

m = compartment mass ventilation flow rate (k9"sec) 

C\> =specific heat of air (kJA<g·K) 

tt: = convective heat transfer coefficient (kW/m .:·K) 

Ar= total area of the compartment enclosing surface boundaries (m') 

Thermal PEnetration Time Calculation 

~ = (PcoJ1<)(ol2)' 

Where \. = thermal penetration time (sec) 

p =interior construction densitv (kQ/m ~ 

C\> = interior construction heat capaci~ (kJA<g. 1-9 

k =interior construction thermal conductivity(kW/m-1-9 

0 = in~rior construction thickness (m) 

flo= 36068.24 sec 

Heal: Trcnsfa- Coefficient Calculation 

1\: = v(kPclt) for t < \. or (k!O) fort> \. 

Where tt: = heattr ansfer coefficient(kW/m.:·l-9 

kpc = in~rior construction thermal inertia (kW/m z-Kl-s ec 

(a thermal property of material responsible for the rate oftemperature rise) 

t= time after ignition (sec) 

See table below for results 

Area of Co mpa"t ment EndosinA Surface BoundCf'ies 

Ar= 2 (We X l:) + 2 (heX IA0 + 2 (heX l:) 

Where A:r= total area of the compartment enclosing surface boundaries (m) 

lilA:= compartment width (m) 

l: = compartment length (m) 

h.:= compartment height (m) 

A= area of ventilation opening (m') 

Ar= 102.19 m ~ 

Compartment Hot Gas laver Tempa-ature With Force:! Ventilation 

lLToJ/T~ = 0.63(0/m(\, of (I\ AI1'mC\>)<~ J>.> 

lLToJ = ToJ· T~ 

ToJ = lLToJ+ T~ 

02~ 111 A: c 

02&:! t< Me 
J-29

Time After nition t h, AT.,IT0 •r. T. T. T. 

(min) (sec) (kWAn' ·K) (K) (K) ('1:) r•n 

0 0 298.00 2500 7700 

1 " 0.05 0£7 20107 499.07 22S.o7 438.92 

2 '" 0.04 0.76 227.78 525.78 252.78 487.01 

3 '" O.o3 082 24503 543.03 270.03 518.06 

4 '" O.o3 087 25805 556.05 283.05 541.50 

5 "' 0.02 090 268£3 566.63 293.63 560.53 

10 '" 0.02 102 30433 602.33 329.33 624.79 

15 "' 0.01 1 .10 327 37 625.37 352.37 666.26 

20 1200 0.01 1 .16 344.77 642.77 369.77 697.58 

25 1500 0.01 120 35890 656.90 383.90 723.01 

30 1$00 0.01 124 37087 668.87 395.87 744.57 

35 2 100 0.01 128 38130 679.30 406.30 763.35 

40 '"' 0.01 131 39058 688.58 415.58 780.04 

45 2700 0.01 134 39895 696.95 423.95 795.11 

50 $000 0.01 136 40659 704.59 431.59 808.86 

55 $$00 0.01 139 413£2 711.62 438.62 821.52 

so $~00 0.01 141 420.15 718.15 445.15 833.27 

Hot Gas Layer Temperature 

Forced Ventilation· FPAMethod 

900 

800 

~700 

'o:600 ,..,. .a 500 

~400 

E3oo 

~ 200 

100 

0 

0 10 20 3J 4) &l 60 

Time (min) 
J-30

METHOD OF DEAL AND SEYLER ll.~ tr~~:SFP$ 1-fm:b.-d.C'! PrctMJm a?t./~~. ' &Ill en ~ P~~ ~liS. 

tt;lltll'\'lnt rer co~m~ ent Ol ul aU n 

••• i! fC ~ 'btt< t, 

\N ~ 1~ •• • ~at1J<I '1i I coe lfbt. lt $'/V,fll _.-1() 

kpc • "~f.)f CO Ut e1)H ~ Pll<tlll~ 111'1 f; tV tll _. 1\l_.~~C 

(;i ~ Pll<tlpope lt{ flll <l~ II.'IIIH PO"bl: 'bt ~ lab OT,IIlpUatm lla) 

;; • 1i •:t;H $$ Of II' lbiiiiii!J ll) 

•• • 0.022 kltV,tll .. -K 

Aru ot COmpartfl ent Enclo•ln}l Sutf\'lu Boundlllh t 

.t..,• 2\W x 1) + 2 (. , XW,) + 2(. , X I) 

.:.., - 102.1$ Ill .. 

compartment Hot Gil t Layer Tern pnll1Ure W1l Forced w ntlla11on 

V\••ue ~T~< • T,.• 1ppe I tr tga> 'Ill~ 1.'11111! Ita .. )We <llllbiHt(IQ 

T,.• <llllbl! 1t a11' '~'~ ~ ratue (19 

1600 

1400 

It 1200 

f 1000 

~ 800 

• 

~ 600 

~ • 400 

200 

0 

Q • •eat 1? 1:<16e "'' OftU life $ 'lV) 

m- 0011lp.'ll11lutma" ve 111lltm TDw rat~ c) 

c,• pe ~ •eatoTalt ~ 

•· • co1vect11e •eattou "' CC* m: l! 1t t;\lVJII .. ~ 

,t.,, • btll<ma OT1U CCtllp<tl1lM lte IC." Ii9 HIT<t:.: bOI "1<111:$ (II) 

~,~;; ~ ~ T, 

,-- -

~ 

Hct Oas Layer Tempel<lture 

F oroed \kntilation • Deal and Be~er Method 

.,... 

-

"' 

0 10 20 30 40 

Time(mi"l) 

T, 

!ll 

;;, 

m; 

60 
J-31

Summarvof ResUt 

Hd Gas Layer Temperature 

F' orced Ventilation 

1500 

1400 

1300 

1200 

1100 

~ 1000 

- goo ~ 800 

1!! 700 

~~~~~~~~~ ~~ ~~ ~~ ~~ ~~ ~ -- ~h:-:1 ~ _ , ........ ,. .. ,,,, 

--

f 600 1- 500 

400 

300 

200 

10~ t:::::::::::::::::::::::::::::::::::::::::::::::::::::j 

0 10 20 

MJUIIM 

30 

Time(min) 

40 50 

The above calculations are based on pinciples de'Wioped in1he SF'PE Haldbookof Fire A-otection 

&IQineerinQ, 3"' Ei::lition, 2002. 

C-'cutnims are based on certan assurrptDns ard have irherentlimitJ!ions. The results of such 

cabulalims may or may rot ha'W reasonaHe p-edictiw capabihies for a gi'Wn situalim, and should 

onlybe interpreted byal ilfonned user. 

Plthough each calcdation in the spreadshec has been wi1ied with the results ofhand c-'cdatDn, 

thEre is no absolute guarartee oflhe accU'3cyoflhese calco1alions. 

Alyquestims,corrments, concerns. ard suggestions, orto rEPOrt an error(s) in1he spreadsheet, 

please send 3l emal to nxi@Jlro.govormxs3@:flro.gw. 

60 
J-32

Problem 4: Compartment with Liquid Pool Fire Scenario

Problem J-4

Problem Statement

Consider a pool fire caused by a 38.0 liters (10 gallons) spill combustible liquid (kerosine oil) in a

0.55-m (6.0-ft ) dike area in a compartment with a concrete floor. The kerosine oil is ignited and 2 2

spread rapidly over the surface, reaching steady burning almost instantly. Compute the HRR,

burning duration, and flame height of the pool fire. The dimensions of the compartment are 6.0 m

wide x 6.0 m long x 3.7 m high (20.0 ft wide x 20.0 ft long x 12.0 ft). Two cable trays are located

above the pool fire at heights of 2.15 m (7.0 ft) and 3.0 m (10.0 ft), respectively. Determine whether

flame will impinge upon the cable trays. Assume instantaneous, complete involvement of the liquid

pool with no fire growth and no intervention by the plant fire department or automatic suppression

systems.

Solution

Purpose:

(1) Determine the HRR of the liquid pool fire.

(2) Determine the flame duration.

f

(3) Determine flame height (H ).

(4) Determine if the flame will impinge the cable trays.

Assumptions:

(1) There is instantaneous and complete involvement of the liquid in the pool fire.

(2) The pool fire is burning in the open.

(3) The pool is circular or nearly circular and contains a fixed mass of liquid volume.

(4) The pool fire is in the center of the compartment or away from the walls.
J-33

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 03_HRR_Flame_Height_Burning_Duration_Calculations.xls

FDT Input Parameters: s

Enter the following parameters in the spreadsheet (values only):

- Fuel spill volume (V) = 10 gallons

dike - Fuel Spill Area or Dike Area (A ) = 6.0 ft2

- Select Fuel Type: select Kerosine from the combo box

Note: When Kerosine is selected, its properties are automatically selected from the

table and entered in the corresponding input cells.

Results

Heat Release Rate*

kW (Btu/sec)

Burning

Duration*

b

t (min)

Pool Fire Flame Height*

Hf m (ft)

Method of

Heskestad

Method of Thomas

890 kW (843 Btu/sec) 24 2.7 m (8.8 ft) 2.3 m (7.6 ft)

*spreadsheet calculations attached on next page

Both methods for pool fire flame height estimation show that the flame could impinge

upon the cable trays.
J-34

Spreadsheet Calculations

FDT : 03_HRR_Flame_Height_Burning_Duration_Calculations.xls s

CHAPTER 3. ESTIMATING BURNING CHARACTERISTICS OF LIQUID POOL FIRE, 

HEAT RELEASE RATE, BURNING DURATION, AND FLAME HEIGHT 

W n lon IM+S.O 

11~ 1:I O'ollrt.l O.I~ CJU U llol~ I~ ~~~ahdNoa I~ ,lo.lll1fV <IU ~I Cf\ ~ 1~1\t l'dlllll1:f I<J\Iol J>OCI·~. 

Flmom~- tn VBlO'NCB le.ut a.-~oll> 1•~ . 

f'!lllllmt-n tn GRESI CB le ~ Alltlm~ t~.\lt; e"'~-4 Tllm 1" OFOPOO'N III.IEIIU1\lr 11" Fll~ e"'~-4. 

ll ~<l\llhl .,\llt.t~\~1 ~~ ~11~4 1fJ I~ w·~~m~l~ 1>~~4 o'.'.:t.~ f w~<l'k41n •~ •1ou1 

~~~oltb . 1111 fl>l~~ fi'HI IIJ>I ~ol~'ol ftO.f~ :C l ~IICff ... ~ V.I I'fi~Oly h~~l (l) . 

11~ I1:11>~1 h h IIUII.B:> fl.., ll>~ l~ll>rtr~ ~lfHif~ fl lf lol~k. 

IN Pili PABAMfifBS 

htl CltiiVCI\IM M htl Cltll f.f~~ ct Ob ;r~~ O'<, ..) 

l.bll 61, ..... ),1 ~ 01'htl(lol") 

Eftd ~ ~~~~l d' o~to.n co01' hd (til ...) 

htl ~n:l lj ) 

8o\f>tle;:ai~ CO b1 {t l') 

flo~t.knl;..t Tttolt>~•~'-•~ (r) 

G<~.lbiCNII Ao:dff~l .,l ~.8 "•••' 

fhlt.kni .A• Ofn:l.- (p ) 1.18"""'' 

I Ollc ula' I It ~: f.) okn:l ljW I411 M~e:alyo:a~I'Ath .Aiii>ltl'llfll 'nloll>ff~f~ (rJ iV.Ii 

Til em.tAl PftO PERTtee DATA 

6URIIIIIG RAT EOAT A FORU l UIOIIYOftOC.AA&j ll FUEl" ' 

"" 1.1.::1 1 Sm1rt,~ tt.ok ~~~~1 01' Cfli>\I CI'\ o~n tt.· lol (l:lllol ) II .. {t:J,14 ) {t:oJ,\o'o ') 

'·~·~ 0.017 !"'"" , to; 

B~l:l O.OIS P~.tro ••• klb't o.as .S,i'OO 

k=~ 0.<0; .0, 0> '' ll~b't ~ o.a• 

0.01 .. 

H

,.., 

,i'OO ~ >\.l~l'f Of» .. ,.. ~~ A: l:·~ o.ou .S.tOO ••• '"""' O.ot8 

~!:: oo:• Oki)' Ehtl 0.<0; .. k""' o.oos H ,i'OO .. cfnt ows .),i'OO 

Ok

'ti

~l 

III~ O.a>9 

o.oos """' H , £0 ~ •• JP·• 0.0<0 .) ~ '" "" O.a<• """ 00 

11~ 1:11MI Oll, ll)'oiiOQ't>Cfl O.a>9 $ 1 ct o:nn~1:ao~u lUI O.<OS ~~ ... '" hd 01, HNo'.J' oms 39,i'OO &70 

Cl\ok OII omn """ ~~. .. ~ 01 O.a>9 .. .., ~ 

UlN Qt~<l'kol \1:11.~ B*I ~u B'I.I .:at.~ 'B'ki " ~\~ 

~•u•«U ~ ........ ...-.-4 ... h _,.,.,,. _,_ '-'~<-·"'·~--~,/<.. 

............. 

(>!.(;>,.. 

Bii>lll:~ Ccn1 1:1'11 

t: .... ol e,l,~t Fll'l T11" 

I I ·! 

'"' e~l'lltt t~4tWt4 ~tt t 'J>t 

'"' tt~ ~n ·u~n ~.7 

~.7 

.. 

... 

... 

.. 

0. '·' 7 ,. 

2.1 

'2.1 ·' 

'" ..

0.7 

1. '"' 7 

,. 

0.7 

B*I ~\~ 
J-35

ESTIMATING POOL FIRE HEAT RELEASE RATE 

P,Ui 1~ •o: : S ,=p E .'·f~.;cbc..W. ot ,={,* P:o lo;t ~ e.g t. tr,g , :j"' 6:1 lb •, 2002, P~~ J-25. 

Q = m"lLH ~.,, (1 • e ""0

) At...., 

Where Q =pool fire heat release rate (kW) 

nt' =mass buminQ raW of fuel per unit surface area (kWm2-sec) 

lLH ~.,, = effective heat of combustion of fuel (kJA<g) 

A= ~o. .. =surface area of pool fire (area involved in vaporization) (m2

) 

kP =empirical constant (m ·) 

D =diameter of pool1ire (diameter involved in vaporization, circular pool is assumed) (m) 

Pod Fire OiamSer Calc:ulal:ion 

~~o.. = 71()"/4 

Where At...., = surface area of pool fire (m2

) 

D =pool fire diamtl>!r (m) 

D = v( 4A. ~o../79 

D = 0.842 m 

ESTIMA liNG POOL FIRE BURNING DURATION 

(U:IH:I> Wlli tel.1t11W . tU 'll.'l>. pollt, II ~ 1J<m1HIIUOII, 1~ l'lle 

t•~a bd 

t:.=4V/7C/ v 

Where t:. =burning duration of pool fire (sec) 

V=volume of liquid(m' ) 

D =pool diameter (m) 

v = reQression rate (nv'sec) 

CalcUction for Ret=~ression Rate 

v = rrt'lp 

Where v = reQression rate (nv'sec) 

rrt'- mass burninQ rate of fuel (lq:r'm2-sec) 

P =liquid fuel densitv(lq:r'm:t) 

v = 0.000048 nv'sec 

BurninA Duration CalcUction 

=4V.mD ' v 

ESTIMA liNG POOL FIRE FLAME HEIGHT 

lvETHOD OF HESKESTAD 

P,e'IHUO: : =PE.'·f~.i<b~;.W. oT.:i.* P:Ulo;t~'\~ S:g ll l'iig .':!" E<IIIIU, 19i't5, Pag: 2-10. 

,. Ho=D.235 Q · 1.02 D 

Where H, = pool fire flame height (m) 

Q =pool fire heat release rate (kW) 

D =pool fire diameter (m) 

Pod Fire Flame HeiQ-4 Calculation 

H1 = 0.235 r:fo • 1.02 D 
J-36

METHOD OF THOMAS 

"-''""''"" ';1-~'I:H..,<I'<I<!<>tclf,IOI'-ft:>fll;.olJIIO .. 'II t''tAl.tlll ~~ ~'>o~:t.lll).l 

H•• 42 0 QA•Jp.,v 9 D)~' 

V\* ~ te H • poo1111e ll.'llll ~ ~ tJ•t {II) 

m• • maa UUI<II~ 011Uipe I UltH 10:.: <liM ;J;<Ihl _.~~¢) 

,.,.. <rll ~ •ta ltdU $l•f t;g ,tll ) 

0 • pOOITU d l'WIHtH ll) 

\1 • <ll<ri lti1J)Iala:o: ~ o 1m fll A: J 

Pool Fi r~ Flam~ Hil OI Ui n 

H,•J2 D QA"I p,.v g OJ)"L 

I!H,= U 2 m 

Fltmt HtiGhtCIItulttlon - lummtrw otRuulh 

7.SO Tt 

ESTIMATING POOL FIRE RESULTS FOR RANDOM SIZE SPILLS USING INPUT PARAMETERS 

Aru (Tt) Ana (m '') am~ur lin Q~ f.,tH 

1 (U)3 o.u 1.1$.$2 85~7. 7 

' 0.13 0.43 23UJ 4.23$.$4 

' (1.2$ ~0 444. 3~ 235U3 J 0.$7 ~3 53$.2$ 2 141.77 

' O.Jii o:rr 74 HO 17 1$.41 

' 5~ (1.$4 333.3 1 1427.$5 

' ~5 0.3 1 10$$.2$ 122$.$7 

• O.?'J 0.$7 113US 1070.$$ 

' o.u 1.0$ IU U 7 $$ 1.$0 

" 0.$$ U)$ IJ$$.1$ $SUI 

" un 1.14 IUUI 778.32 

" 1.11 1.1$ 1773.3$ 7 1$.32 

" 1.2 1 U J l!llS.IS ~53 01 IJ 1.30 1.13 107S.oll s 11.33 

" U3 U$ 222U3 571. 14 

" u~ 1.54 3~US 428.35 

" 2.$2 1.72 $70US U HS 

" us U$ 7JIU5 17 1.$4 

75 U 7 us 11 12$.3$ I IU$ 

"' 3.23 UJ 14$$ 1.3 1 SS 7 

"' Ht th t tld H, 1t lhcma • UJ ... 5.33 $.13 

us 5.37 

?'.~I uo 

3.27 7. 1$ 

3.U uo 

us 3.02 

3.$$ u o ~ us 

IU 7 3.07 

IUS U$ 

ILJIJ U 7 

11.74 3.34 

12.0$ 16.10 12.$7 IO.JS 

1$.7$ 11.55 

IU3 IU S 

13.10 IS.S7 

2.1)~ IUS 2U $ 20.20 
J-37

Caution: The purpose of this random spill size chart is to aid the user in evaluating the 

hazard of random sized spills. Please note that the calculation doe not take into account 

the vise os~y or volatility of the liquid, or the absorptiv~y of the surface. The resuns 

generated for small volume spills over large areas should be used with extreme caution. 

The above calculations are based on principles developed in the SFPE Handbook of Fire 

Protection Engineering, 2nd Edition, 1995. 

Calrulations are based on certain assumptions and have inherent limitations. The results 

of such calculations may or may not have reasonable predictive capabilities for a given 

situation, and should only be interpreted by an informed user . 

.AJthough each calrulation in the spreadsheet has been veri1ied Wth the results of hand 

calculation, there is no absolute guarantee ofthe accuracy of these calrulations. 

My questions, comments, concerns, and suggestions, or to report an error(s) in the 

spreadsheets, please send an email to nxi@nrc.gov or mxs3@nrc.gov. 
J-38

Problem J-5

Problem Statement

Consider a compartment with cable trays at 4.60 m (15 ft) above the floor. The cable trays are very

close to the compartment walls. If 7.6 liters (2 gallons) of lube oil spills covering an area of 1.4 m2

(15 ft ), what location type of fire source will allow the fire flame to impinge on the cable trays? 2

Solution

Purpose:

(1) Determine what type of fire source will impinge upon the cable tray.

Assumptions:

(1) Air is entrained only from one side during the combustion process.

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 04_Flame_Height_Calculations.xls

select Wall_Flame _Height for wall fire analysis

select Corner_Flame _Height for corner fire analysis

select Wall_Line_Flame _Height for line fire analysis

FDT Input Parameters: s

Enter the following parameters in all spreadsheets (values only):

- Fuel spill volume (V) = 2 gallons

dike - Fuel Spill Area or Dike Area (A ) = 15 ft2

- Select Fuel Type: select Lube Oil from the combo box

Note: When Lube Oil is selected, its properties are automatically selected from the

table and entered in the corresponding input cells.

Results

Fire Source Flame Height*

Hf m (ft)

Wall Fire 4.02 (13.18)

Corner Fire 6.07 (19.93)

Line Fire 2.01 (6.59)

*spreadsheet calculations attached on next page
J-39

Spreadsheet Calculations

FDT : 04_Flame_Height_Calculations.xls (Wall_Flame _Height) s

CHAPTER 4. ESTIMATING WALL FIRE FLAME HEIGHT 

Version 19l5D 

Th 'b ttA' II tjC<I I 1.10) " tili~ ~ W<tll11fe 'll.'IIIH ~ .;~•t 

Plli'\'IDI~tH lll Ell WCEll Silr~ Entlnd by 1U UtH. 

Plli'\'IDI~tH ln GREEII C EllS llr~ Automll11CIIII}' h iH,dtrom 1ll$ DRO P OOVVII f.1EIIU fo r11u Fll&l S&IHUd . 

. .:. 1 HbH\IH ltOI1j>ltV<IIH$ <I ~ cat:l 1.1t&d by1U plea ~ •Ht<Ud baH d Ol tJa ltH rn. d II ~ " Pit 

para•"&'" . n t $pl?a<th&t a; pl ~daut $&cue b at.to•:t &no" <IH b a w1o1g utrv 11 a o:tt('). 

Th c ... ), 1111U IIUP, ~ $. 0 1.:1 b& !?ad l=*'bl& <11 <U<II($1$ ~mao:. 

INPUT PARAMETERS 

F H I Sj> Ill Vo ltiiH (1/) 2 00 g.'lt)" FHI ~> III.oi.Jea r Ot:&.l'.IM ,'.,,W 15.00 1t 

1.1<16$ 61UIItj Rate 01 fHI II ") OD» l«atll•;ec 

E11'ectiJ& HMtOTCOIIIb"tDI OTFH I ~.,~ '"'"' I:J.t;g 

Elll pU~ Ut.'llt i,!:P) 0.1 m 

I Calculate II 

THERMAL PROP ERTlE$ FOR 

BURIIIIIG RATE DATA FOR LIQUID HYDROCARBOII FUELS 

O!M6111 

139 . ...... 

fHI r.1as' 6'" 119 Ra' ~at tll b"OH Bllp lltaiCOI$tllt Select Fuel Type 

, .... ;t gihl :t ) H .. ,. iJ;J,t;g) I:P 1m ' • I luba ~ ·I r.1 l 0.017 20.000 100 Scrdl to d~ r~d 11.1 1 yp~ tiH n 

EUa•o l 0.0 IS 26.800 100 Oick on n 

6 1t.'IH 0.078 45,700 2.7 

6uze ~ 0.085 ,0,100 2.7 

na ~ 0.07' U ,700 1.9 

~ptiH 0 .101 U ,600 1.1 

XV'"H OD9 '0.800 u :. o:tn~ 0.041 25.800 1.9 

o• ~ 0.018 26.200 S.l 

OI:Q EU ~I 0.085 3'2 00 0.7 

6uze ~ ODIS U ,700 3.6 

Ga>OIIH 0.055 43,700 2.1 

OH ~ OD» 43.200 3.5 

DIH~ I ODIS " ·'00 2.1 

JP-' 0.05 1 43.500 3.6 

JP .. 0.05' 43.000 1.6 TlaWbPII~I 0 11, Hy'tiiOCalbOI OD» ' 6 .000 0.7 

561 S III::OI Tla"DPIIU n •:1 0.005 28.100 100 

fH 10 11, HM1/V 0.035 39,700 1.7 

CUd! 0 11 0.034 ' 2.600 2.8 

lll ~ 0 1 OD» ' 6 .000 0.7 

UH ISI=*Ciftd ll ~ E1U1 11 ~ El' ,_ ~ E••1 11 ~ 

It~ tr~l"o2 : $.=?$1-im(b. ... .\('~ ~ l" <t~'C.:>n ~' ' =atN, >:». 
J-40

t-hat ~lease Rate calcUaticn 

*' ': S. P$ ~..._'\ ('(t=l'f:>i>~«t .:r.=rt~~~ 3'" :a v, 'l.\.l':. Fl:\IC 3-ZS. 

Q = m"AH. .... (1. e '"" j A .... 

Where Q =pod h hea release rae (kVV) 

m"= mass buninQ r.ne of tiel per urit surDce na (kWJT{-sec) 

AH..,..t= etf!cti'W hea ofcorrbustDn of tiel (kJ'<g) 

A= A .... = surDce area of pool fi~e @rea imoi'Wd in 'Wporizalion)(m') 

l4l = EmPrical co1'613nt(m ·) 

0= da~rofpod ire (dianEterimotwd n 'Wporizalion,ciroubrpool is assumed)(m) 

(Uq.~ids wth rel<ti'WiyhQh flash poilt,like11'3nsi:lnner 

oil req.~ire localized healing to actie'W ignition) 

Pcd Are D<rneter calculaticn 

= >(f~ 

0=>(4A "'J 

Where Al~.n = surface area ofpool ire (m") 

0= pool1i"e dianter (m) 

O= 1.332 m 

t-hat ~lease Rate calcUaicn 

Q = m"AH ..... (1·e ~u)A».o~ 

0= 151SD2 kW 

t-hat ~lease Rate Per Lhit LE'flghof Are calculaticn 

0'= Oil 

1436.91 Etuo'sec 

Where a= heat ~ease r.rte per unit length (kVl.O'm) 

Q = fi"e heat~elease r.ne oflhe fi~e !l<Vll) 

l= len~h oflhe h sruroe lfn) 

Are So..rce Lerg:h calcUaicn 

lx W= A.l~n 

lxW= 

L= 

0'= Oil 

0'= 

1.3;14m" 

1.180 m 

128423 kVl.O'm 

ESTIMATING WALL FIRE FLAME HEIGHT 

*' ': FI"A.t=l'f:>i> .:r.Hmd>:'c. . ·o" St.'lfbr, :l.\.l'.\ ;>~ :t- ).:.. 

H,...,.,= OD34 a l)':l 

Where H. ••• u,= wall fire 1ame hei~ (m) 

a= rae of heat ~ease perunt len~h ofthe h (kWtn) H,...,.,= OD34 "'~ 

Iii. liM 

The abo'W calcolalions are based on pinciples de'Wioped in the S FP E 1-bndbook of Fire 

Prttection &Qineff'inQ,3"' Ei::lition, 2002,and NFPAFi'e A-otectim 1-Bldbod<, 19"' 6:1ition, 2003. 

C31colalions are based m cenain assurrptions ald ha'W inherent lmitJ!ions. The results of 

such calcolaims mayormaynct ha'W reasonable prEdicti'W capa~lities i:lr a gi'Wn stuaim, ard 

shouH mlybe interpraed byan infonned user. 

Mlrugh each calcolalion in the sp-eadshea has been 'Wri,ed with the ~eslfts of hard cabutRDn, 

there is ro absolute gua~antee oflhe accU'3cyofthese calcolalions. 

Alyquestions,corrments, cmcems, and suggestims,orto repon an error(s)inthe spreadsheet, 

please send 3'1 Em<il to mO@flroQovormxs3@flroQOV. 
J-41

FDT : 04_Flame_Height_Calculations.xls (Corner_Flame _Height) s

CHAPTER 4. ESTIMATING CORNER FIRE FLAME HEIGHT 

Version 19l5.0 

Th DlttA'" 9 ca l 1.'11)) " H thl ate !U COIHI111~ ll.l'll ~ ~ _;~•t 

Plli'\'IDI ~tHt In YEllOWCEllS 11r~ Ent~r~d bj' Ul$ UtH . 

PIII'\'IDI $tHt In GREEII CEllS llr$ Automii11CIIII\' $$1&e t$d TORI tu DROP OOVVII f.1E IIU for 1l$ FU$1 $$1&CUd • 

. :..1 HbHq ~ ato t1plttJ<IIH$ ate a• H1t~d by1U p1Md h~t<Ud l>aHd 01 !J<IIH$ p~ ift d II 1U ltiHt 

para111&'" . TU~ $ptea<laHt 1$ pi ,~d aut $&CU to <WJO.:I &IIOIH II& to a WIOI!J U 1Jy II a 0: ~~~) . 

Th C ... ), 1111U IIUP,~ $ •o••:t b& l&ad I:HOI& <U <11<11($1$ 1$ mad& • 

.tu&a ' t... ....) 

1.1<1 6$ 6U.II!J fta' TFI II ") 

Elf! C111& H&atof CCtll bl $11) 1 OT fl& I !:. ...,.~ 

Elll t•• "t.nt t;p) 

THERMAL PROPERTIES FOR 

Calculate I 

BURIIIIIG RATE DATA FOR UIO HYDROC.ARBOII FUELS 

r.1a " 61 nt1g Rate H&at01COIIIbU 11,_ 

fHI ..... gfln 0) !:.H.,.,, iJ;JJ:gl 

r.1&Gal ot 0.017 20.000 

EU<UOI 0.0 IS ~.800 

•tu ~ 0.078 45,700 

6U~H 0.08S W,IOO 

HH<m O.OH U ,700 

~pt.'IH 0 .101 U .600 

XV~H OD9 w.soo :...o:toH 0.0' 1 25.800 

Dt « aH 0.018 ~.200 

o~:uv en ~• 0.08S 3'2 00 

6U~H 0.0'8 U ,700 

a>O IIt ~ o.oss ~. 00 

l<tiOHH 0.039 .200 

OI:H I 0.0'5 U ,,OO 

JP-' O.OS I .soo 

JP .. o.os' ~.000 

Tla U 1HII U 0 II, H((IIOC<I d)o• 0.039 w.ooo 

SOl S l•:o• TraU'blll ~I Fl• •:1 o.oos 28,100 

fHI 0 11. ~<tiiY 0.03S 39,700 

nd~ 0 1 0.03' !2.600 

L•b~ 0 11 0.039 w.ooo 

UH ISpecm.d lt ~ E•~• lt ~ E•' IV<tiH 

' == - -

Em Utllt 

•:P•m 1

' 

100 

100 

2.7 

2.7 

... 

1.1 

1.1 

... 

S.l 

0 .7 

,. 

2.1 

3 5 

2 .1 

,. 

.. 

0 .7 

100 

1.7 

za 

0 .7 

E•~• ~ 

Select Fuel Type 

Ll!.OL!:•• JH 

Scrdl to d~ r~d 11.1~1 yp~ UHn 

Oick on n 
J-42

Hea Release Rate Calculaion 

RUm •o:: SfPE ... r.cbook. t l" ~ P,'\11?U\Ifl 5ig',~"" ll . J .-.t Ed t\lfl. 200t, P~~ ~2.5 . 

Where Q = pool fire heat release rate (kW) 

m" = mass burning r a~ of fuel per unit surface area (kg/mz·sec) 

lLH ~n= effective heat of combustion of fuel (kJA<g) 

At= An~= surface area of pool fire (area involved in vaporization) (m) 

kP =empirical constant(m.1

) 

D =diameter of poolfire(diameter involved in vaporization, circular pool is assumed)(m) 

(Uquids with relatively high flash point, Ike transformer 

Pool Fire OiamSer Calculation 

An~ = 71() z/4 

D=v(4Au:t~ 

oil require localized heating to achieve ignition) 

Where Alb= surface area of poolfire(m) 

D =pool fire diam~r(m) 

D= 1.332 m 

Heat Release Rate Calculation 

Q = m"lLH ~n(1-e "~ 0

) A..t ~ 

Q = 151602 kW 1436.91 Btu/sec 

ESTIMATING CORNER FIRE FLAME HEIGHT 

Renre •o:: ~~;rl/ d Tukllrragt. 1\..\l~ .:g tTUrb:. tD.'ft.st..'\~ l" tAr. d, ~ N:m~ ;o ti ys.s "' ~ Gr.11r:t1. • 

Grovm. • ..,,~i'<f ,;g t~ 2111 aturr rn r. :'i? C..'\'?:'i? c~. r. ,-: 7tr. su ;y *\..~ a, 7t 5ig ll m (ASA..'IE,) 1 ~J. 

'(o:n~(,t = 0.075 Q J.'> 

Where Q = heat release rate of the fire (kW) 

o.o75 a"'" 

The above calculations are based on principles developed in the SF PE Handbod< of Fire 

Protection Engineering, 3" Edition, 2002 and Hesemi and Tokunage,1983. 

Calculations are based on certain assumptions and have inherent limitations. The results of 

such calculations may or may not have reasonable predictive capabilities for a given situation. 

and should only be interpreted by an informed user. 

Anhough each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolute guarantee of the accuracy of these calculations. 

Any questions, comments, concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or ITO<s3@nrc.gov. 
J-43

FDT : 04_Flame_Height_Calculations.xls (Wall_Line_Flame _Height) s

CHAPTER 4. ESTIMATING LINE FIRE FLAME HEIGHT AGAINST THE WALL 

Ve<Sion 1805.0 

The following calculations estimate the line fire flame height against lhe wall. 

Parameters in YELLOW CELLS are Entered bythe User. 

Parameters in GREEN CEll$ are Automatically Selectedfrcm the DROP DOWN M ENUforthe Fuel Selected. 

All subsequeM oUiput \Glues are calculated bythe spreadsheet and based on wlues specified in the input 

parameters. This spreadsheet is protected and secure to a wid errors due to a wrong entry in a cell(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

Fuel Spill \A:IIume (\1,1 200 galb" 00076 .... 

Fuel Spill .A"ea or Oib ~a (A.».n) 1500 ii' L:¥.1• hi ~ 

Mass Burning Rat»l of Fuel (m') 0039 tgllil ~~c 

Effective Heat of Combustion of Fuel (AH,..,,) 48000 •:J.t;g 

Errpirical Constant (kP) 0.711'1 

II Caluhtell 

THERMAL PROPERTIES FOR 

BURNING RATE DATA FOR LIQUID Hi DROCARBON FUELS 

Bnp1nca1 

Fuel Mass Burning Ra~ Heat of Combustion ConstaM Select Fuel Type 

m"(kghn1-sec) AH....,, (kJo1<g) kP(m 1

) . Methanol 0017 20000 100 Scroll to desired fuel type then 

Ethanol 0015 26~00 100 Click on selection 

Bumne 0078 46.700 2.7 

Benzene 0085 40.100 2.7 

Hexane OD74 44,700 19 

Heptane 0.101 44~00 1.1 

~ene 009 40~00 1.4 

~one 0041 25~00 19 

Dioxane 0018 26~00 5.4 

DiethyBher 0085 34~00 0.7 

Benzene 0048 44,700 36 

Gasoline 0055 43.700 2.1 

Kerosene 0039 43~00 35 

Diesel 0046 44,400 2.1 

P-4 0051 43500 36 

P·5 OD54 43000 16 

ran sfonner Oil, Hydrocarbon 0039 48000 0.7 

61 Silicon Transfonner Auid 0005 28.100 100 

Fuel Oil, Heavy 0035 39.700 1.7 

Crude Oil OD34 42~00 2S 

lube Oil 0039 48000 0.7 

User Soeci,ed \I.Jiue Enter \I.Jiu e &Iter \I.Jiue Enter\lalue 

- .. 
J-44

Hut Rtlu 1t Rate 011cu1 a11o n 

~-.,~rc~:si=P=Htlltl>.-.:io. di=l h:fc-3:.:r.~'N;J 3 " =a:.:r. ~'\l'2 l'l:\it :t-ZS. 

a -m·t:, ....,, o.:- .4.. 

'lVhle a • pooiTII! hat1e1:a.e 1.'1' ;J:\t\1) 

Ill' • 111<1 6$ b' Ullg 1.'1' OT p~ I U It$ UT<t:.? aJ~a $ 9 ,111 :t ) t:,H .. _.• Tt CU ~ hatOTCOIIIbUU,_ OTfHI ;J;J,t;g) 

.t..,• A,"'-" • $ UTaO: aJ~a po I111e \1 1~<1 IUtOI1HI .. ll<tpOitaOH) (11 ) 

t;p • e111 ii. CO Ut.'llt {II ) 

0 • dblll ~' IOTpOOITte I$J hlll~~ llltJOt.r~d . 11<tp011Za1m , CICU.'IIpoOII$ <1 HIJI~ (~ ~~) 

(U:I••:I6 WIG I~ l.'ltl1~ If. •:" Tb$. POIIt lh 1JaiU PII ~ I 

111 1• 11e ca l~d haU1g b ~ •_;~•II)H) 

Pool Flrt thmtter 011cu1a1on 

.:.<J.., • .tO:t" 

O• 4.t.. ~) 

'Nhre A,"""• IT<t eaJea poo ltlle ~~ ) 

o- poo1111e dh•ll~ 1 ~~) 

o- L3H m 

Hut Rtlu u Rate 011cu1a11on 

a ·m·t:,H....,t (H .o,:.") A""" 

a • 1$1~.0 2 •:'N 

H&at Rtlu 1t Rate ~r Unit Ltnn11l oT Fire Otlcutauon 

a·· aJL 

'Nhle a· • hat te l?aH 1<1, p~l 'It 1:1911 $VWhl) 

a •Til! hat 1~1:a.e 1.'1' on e 111 e t:V'V) 

L• IHgU OTUe life $0UO: ~~) 

Fin s ouru Ltng11l 011cu1a11on 

LX W• AIM 

LX W• 

L• 

a· · aJL 

a·-

1.39 ' m" 

1.130 Ill 

ESTIMATING LINE WALL FIRE FLAME HEIGHT ~'tr~rc~ NR"A ~Prctc-3:.:>r.Htlltl>.-.:fo.. 11" ad!'br, :l.'\)3 !"~ 3-13:. 

H • .,.. .. .,,. 0.0 17 a·:t.:. 

Whle H,.,.. .. .,,- wa ll111 e ll.'lllle ~•_;t II ) 

a· • 1<1, OT Hat te l?aH pe I U It I? 1(11i OT1ie llle .,W,tll) 

H ........ ,. o.ol7 a·"" 

IH~~: "~= 2.0 1m U3n IIJa 

ld.lil 

n e .. )OV~ ca ' 1.'10,_$ <II~ l>aH d 01 p iiiCj)l?$ d~ ~ tt ~d . U e S FPE Hauboo•: OT File 

PI ~COH EUIIIH fll(l, :f~ 6:1U,_ , 1002, <ti d IIFP A File P D'ctbl H<tl<lbOOI;, 19" 6:111),_ , 1003. 

at •L'~O" ' a1e baa d 0 1 cut111 a>Hmptb" a 1d •ave "hie 1t ttllltiO" ' · Th 1e' u t oT 

H e• cat:U.'IOH6 mar 01111 anou ave teaso1abl! pi~ U:U ~ cap .. u n h 1:11 a gvu $ll'l<tU)I.<tld 

•• ll b~ .,qm,d ){ <tlll 'b lll ~duet 

.:O.Mo •g • e<t:• al ' l.'ltb l " 1U 6prea<thet •a. bH 1 ~1m. d wu Ue teH It oT •a i d cat U.'IO,. , 

Que t 1o a1:4o1'' a~a1' e OT Qe cc•I.'IOf OT 1i H ca 'IO" · 

.:O.Iy q •H tbl$, O:tll IIIU~ . COIO:U$, <ti d H9_;!H OH$, Olb 1eporta1 ~11 (') . U e $p1e<t:l6het, 

pl!aH ~ ld <II e111 <1 llb IXI@IIC.gov OIIJIU 30 11C.gOV. 
J-45

Problem 6: Compartment Fire with Forced Ventilation

Problem J-6

Problem Statement

Consider a compartment that is 15.2 m wide x 12.20 m long x 3.70 m height (50 ft wide x 40 ft long

x 12 ft height) with two forced ventilation rates: 2.4 m /s and 2.8 m /s (5,000 cfm and 6,000 cfm). 3 3

If a fire scenario arises with a fire power of 1,500 kW (1,422 Btu/sec), find the average hot gas layer

temperature for gypsum board (boundary material) that is 1⁄2, e, 3⁄4, 1, 11⁄2, and 2 inch(es) thick at

15 min after ignition.

Solution

Purpose:

(1) Determine the average hot gas layer temperature for two ventilation rates (5,000 cfm

and 6,000 cfm) at 15 minutes after ignition.

Assumptions:

(1) Air properties (ambient) are at 25 °C (77 °F).

(2) Neglect the effect of the cable trays on the plume profile.

(3) The heat flow through the compartment boundaries is one-dimensional.

(4) The HRR is constant.

(5) The fire is located at the center of the compartment or away from the walls.

(6) The compartment is open to the outside at the inlet (pressure = 1 atm).

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 02.2_Temperature_FV.xls
J-46

FDT Input Parameters: s

Enter the following parameters in both spreadsheets (values only):

c

- Compartment Width (w ) = 50 ft

c

- Compartment Length (l ) = 40 ft

c

- Compartment Height (h ) = 12 ft

- Interior Lining Thickness = 0.5 in

- Select Material: select Gypsum Board from the combo box

- Compartment ventilation rate = 5,000 cfm and 6,000 cfm

- Fire Heat Release Rate = 1,500 kW

Note: When Gypsum Board is selected, its thermal properties are automatically

selected from the table and entered in the corresponding input cells.

Results

This problem is solved using the two different ventilation rates and varying wall thicknesses

at 15 minutes after ignition. The following table summarizes the results.

Ventilation rate

(cfm)

Trial Material Thickness (in) Hot Gas Layer Temperatu gre T [°C (°F)]

Method of FPA Method of Deal & Beyler

5,000 1 0.5 225 (436) 274 (525)

2 0.63 241 (467) 274 (525)

3 0.75 256 (492) 274 (525)

4 1.0 220 (429) 274 (525)

5 1.5 220 (429) 274 (525)

6 2.0 220 (429) 274 (525)

6,000 1 0.5 212 (413) 253 (487)

2 0.63 228 (442) 253 (487)

3 0.75 241 (466) 253 (487)

4 1.0 208 (407) 253 (487)

5 1.5 208 (407) 253 (487)

6 2.0 208 (407) 253 (487)

*spreadsheet calculations attached on next page

Following the results of the FPA and Deal & Beyler method, we see how the two methods respond

to different inputs. This problem can be rerun varying time to explore the differences in methods.
J-47

Spreadsheet Calculations

Note: The following spreadsheets show the final result of the solution process. Only the 6,000 cfm

case is shown; spreadsheet calculations for the 5,000 cfm scenario are similar.

FDT : 02.2_Temperature_FV.xls s

CHAPTER 2. PREDICTING HOT GAS LAYER TEMPERATURE IN A ROOM 

FIRE WITH FORCED VENTILATION 

COMPARTMENT WITH THERMALLY THICK!THIN BOUNDARIES 

Version 1805.0 

The following calcolations estimate the hot gas layertemper.rure and smob layer height in enclosure ire. 

Parameters in YELLOW CELLS are Entered by the User. 

Parameters in GREEN CELLS are ALiomatically Selected from the DROP DOWN M ENUforthe Material Selected. 

All subsequent output wlues are calculated by1he spreadsheet and based on wlues specified in the input 

parameters. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a cell(s). 

The chapter in 1he NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

COMPARTMENT INFORMATION 

Compartment VlAdlh (w ) 

Compartment Length 0.) 

Compartment Height (h.) 

lntenor Un•ng Th1ckness (6) 

AMBIENT CONDITIONS 

.Pmb ient Ptr Temper atiJ re (T ,.) 

Specific Heat of Air (c11) 

.Anb ient J:ir Density ( P,) 

THERMAL PROPERTIES 0 F COM PA RTM E NT ENCLOSING SURFACES 

50 DO 1t 

40DO 1t 

12DO 1t 

f------:1,.,0~0 ""% 

1.18 "9111 

Interior UninQ Thermal Inertia (kpc) 0.18 \t iV fll c 

Interior Uning Thermal ConductiWy(k) 0.00017 •:I.N.t!1 4< 

Interior Uning Specific Heat(c) 1.1 t:J.tg-K 

Interior Uning Oensity(p) 960 t<llll 

Note: J:ir density will autom<nic:a lly correct w ilh .Anbient J:ir Temperature (T ,,) Input 

lHERMAL PROPERTIES FOR COivlviOIIIIITERIOR LIIIIIIG MATERIALS 

Material kf'C k c p 

(kVll.tn:t ·Kf -sec Whn-K\ 111<-"<•·K\ (kg An' ) 

152 4 Ill 

12.19 .... 

3.66 .... 

O.o331 111 

25.00 ~ 

2re.OO K 

Select Material 

I !lle;un Board ·I 

.Aiu minum (pure) 500 0.206 OS95 2710 Scroll to desired material t hen 

Steel (0.5" Carbon) 197 0.054 0.465 7850 Click on select ion 

Concrete 29 0.0016 0.75 2400 

Brick 1.7 0.0008 OS 2600 

Glass, Plate 16 0.00076 OS 2710 

Brick/Concrete Block 12 0.00073 OS4 1900 

Gypsum Board 0.18 0.00017 1.1 960 

Plywood 0.16 0.00012 25 540 

Fiber Insulation Board 0.16 0.00053 125 240 

Chipboard 0.15 0.00015 125 800 

.Aemed Conctet»l 0.12 0.00026 096 500 

Plasterboard 0.12 0.00016 OS4 950 

Calcium Silicate Board 0098 0.00013 1.12 700 

.Aiu mina Silicate Block 0036 0.00014 I 260 

Gla s:s Fiber hsul<nion 00018 0.000037 OS 60 

&:pan ded Polystve ne 0001 0.000034 15 20 

User Soecified \l.ilue Emr\l.ilue Enter \l.ilue Enter \l.ilue Emr \l.ilue 

" .... ,, " - . 0 
J-48

COMPARTMENT MASS VENTILATION FLOW RATE 

Forced Ventilation Flow RaW (m) 

FIRE SPECIFICATIONS 

6000 DO !cn11 

Fire Heat Release Rate (Q) 1&1000 •:tl>) 

I Calculate I 

METHOD OF FOOTE, PAGNI, AND ALVARES (FPA) 

RHH! •o:: :pE "iar.dOO~ .:1 ,: i.'l" 'V~UU l.:.,;...,-,•,:g, J " Edltb•. 2002, Pag; J-177 . 

Where lL ToJ = T oJ. T ~= upper layer gas temperature rise above ambient (K) 

T~= ambient air temperature (K) 

Q = heat releaser ate ofthe fire (kW) 

m = compartment mass ventilation flow rate (k9"sec) 

C\> =specific heat of air (kJA<g·K) 

tt: = convective heat transfer coefficient (kW/m .:·K) 

Ar= total area of the compartment enclosing surface boundaries (m') 

Thermal PEnetration Time Calculation 

~ = (PcoJk)(6iZ/ 

Where 

~= 

\. = thermal penetration time (sec) 

p =interior construction density (kg/m ~ 

C\> = interior construction heat capaci~ (kJA<g. 1-9 

k =interior construction thermal conductivity(kW/m-1-9 

0 = in~rior construction thickness (m) 

2254.26 sec 

Heal: Trcnsfa- Coefficient Calculation 

1\: = v(kPclt) for t < \. or (k/0) fort> \. 

Where 1\: = heattr ansfer coefficient(kW/mz·l-9 

kpc = in~rior construction thermal inertia (kW/mz-K)z·s ec 

(a thermal property of material responsible for the rate oftemperab.ue rise) 

t= time after ignition (sec) 

See table below for results 

Area of Co mpa"t ment En dosing Surface Boundc.-ies 

Ar= 2 (We X l:) + 2 (heX IA0 + 2 (heX l:) 

Where Ar= total area of the compartment enclosing surface boundaries (m') 

lilA:= compartment width (m) 

l: = compartment length (m) 

h.:= compartment height (m) 

k =area of ventilation opening (m') 

Ar= 572.28 m.: 

Compartment Hot Gas layer Tempa-ature With Force:! Ventilation 

lL ToJIT~ = 0.63(0/ma. To)v.r.:(l't:Alima. )" ·,_, 

lLToJ = ToJ· T~ 

ToJ = lLToJ+ T~ 

2.832 111 A: c 

J.JS4 t< M e 
J-49

Time After nition t h, AT.,IT0 •r. T. T. T. 

(min) (sec) (kWAn' ·K) (K) (K) ('1:) r•n 

0 0 298.00 2500 7700 

1 " 0.05 038 11249 410.48 137.48 279.48 

2 '" 0.04 OA3 127 A2 425.42 152.42 306.36 

3 '" O.o3 OAS 137 07 435.07 1S2.o7 323.73 

4 '" O.o3 OA8 14436 442.36 169.36 336.84 

5 "' 0.02 050 15027 448.27 175.27 347.49 

10 '" 0.02 057 17024 488.24 195.24 383.44 

15 "' 0.01 0£1 183.13 481.13 208.13 406.64 

20 1200 0.01 0£5 19286 490.86 217.86 424.16 

25 1500 0.01 0£7 200.77 498.77 225.77 438.38 

30 1$00 0.01 0.70 207 A7 505.47 232.47 450.44 

35 2 100 0.01 0.72 21330 511.30 238.30 480.95 

40 '"' 0.00 093 277 A1 575.41 302.41 576.34 

45 2700 0.00 093 277 A1 575.41 302.41 576.34 

50 $000 0.00 093 277 A1 575.41 302.41 576.34 

55 $$00 0.00 093 277 A1 575.41 302.41 576.34 

so $~00 0.00 093 277 A1 575.41 302.41 576.34 

Hot Gas Layer Temperature 

Forced Ventilation· FPAMethod 

700 

~600 ~ 

t..-500 

• 

/ 

]400 

• Gi300 

~ 

~200 

~100 

0 

0 10 20 3J 4) &l 60 

Time (min) 
J-50

METHOD OF DEAL AND SEYLER ll.~ tr~~:SFP$ 1-fm:b.-d.C'! PrctMJm a?t./~~. ' &Ill en ~ P~~ ~liS. 

tt;lltll'\'lnt rer co~m~ ent Ol ul aU n 

••• i! fC ~ 'btt< t, 

\N ~ 1~ •• • ~at1J<I '1i I coe lfbt. lt $'/V,fll _.-1() 

kpc • "~f.)f CO Ut e1)H ~ Pll<tlll~ 111'1 f; tV tll _. 1\l_.~~C 

(;i ~ Pll<tlpope lt{ flll <l~ II.'IIIH PO"bl: 'bt ~ lab OT,IIlpUatm lla) 

;; • 1i •:t;H $$ Of II' lbiiiiii!J ll) 

•• • 0.022 kltV,tll .. -K 

Aru ot COmpartfl ent Enclo•ln}l Sutf\'lu Boundlllh t 

.t..,• 2\W x 1) + 2 (. , XW,) + 2(. , X I) 

.:.., - $72.2$ Ill .. 

compartment Hot Gil t Layer Tern pnll1Ure W1l Forced w ntlla11on 

V\••ue ~T~< • T,.• 1ppe I tr tga> 'Ill~ 1.'11111! Ita .. )We <llllbiHt(IQ 

T,.• <llllbl! 1t a11' '~'~ ~ ratue (19 

Q • •eat 1? 1:<16e "'' OftU life $ 'lV) 

m- 0011lp.'ll11lutma" ve 111lltm TDw rat~ c) 

c,• pe ~ •eatoTalt ~ 

•· • co1vect11e •eattou "' CC* m: l! 1t t;\lVJII .. ~ 

,t.,, • btll<ma OT1U CCtllp<tl1lM lte IC." Ii9 HIT<t:.: bOI "1<111:$ (II) 

~,~;; ~ ~ ~ *= -----!ri' 

t:= 

Hct Oas Layer Tempel<lture 

F oroed \kntilation • Deal and Be~er Method 

700 

600 

E5oo 

~ 400 ...--

Loo / 

~ 200 ~ 

100 

0 

0 10 20 30 40 50 

Time (rrin) 

;;, ~ 

60 
J-51

Summarvof ResUt 

700 

600 

~500 

t., 

~ 400 

~ 300 

~ 1- 200 

100 

0 

MJUIIM 

.......-:: 

ry 

0 10 

Hd Gas Layer Temperature 

F' orced Ventilation 

/ 

20 30 

Time (min) 

/ 

40 50 

The above calcolalionsare based on pinciples de'Wioped in1he SF'PE Haldbookof Fire A-otection 

&IQineerinQ, 3"' Ei::lition, 2002. 

C-'cutnims are based on certan assurrptDns ard have irherentlimitJ!ions. The results of such 

cabulalims may or may rot ha'W reasonaHe p-edictiw capabihies for a gi'Wn situalim, and should 

onlybe interpreted byal ilfonned user. 

Plthough each calcdalion in the spreadshec has been wi1ied with the results ofhand c-'cdatDn, 

thEre is no absolute guarartee oflhe accU'3cyoflhese calcolalions. 

Alyquestims,corrments, concerns. ard suggestions, orto rEPOrt an error(s) in1he spreadsheet, 

please send 3l emal to nxi@Jlro.govormxs3@:flro.gw. 

-- ~h:-:1 

~~ '*YIHU,I'Q:I 

60 
J-52

Problem J-7

Problem Statement

Consider a compartment with an open vent that allows the air entrance at 3.60 m/s (700 ft/min).

Assume that heptane from a tank spills on the concrete floor forming a 1.86 m (20 ft ) pool. The 2 2

edge to edge distance from the pool fire to a certain target is about 9.0 m (30 ft). The target is 3 m

(10 ft) above ground. Calculate the flame radiative heat flux at ground level using the solid flame

model.

Solution

Purpose:

(1) Calculate the radiant heat flux from the pool fire to the target using the solid flame

radiation model and considering the effect of the wind.

Assumptions:

(1) The pool is circular or nearly circular.

(2) The correlation for solid flame radiation model is suitable for heptane.

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 05.2_Heat_Flux_Calculations_Wind.xls (select Solid Flame 2)

FDT Input Parameters: s

Enter the following parameters in the spreadsheet (values only):

dike - Fuel Spill Area or Dike Area (A ) = 20 ft2

- Distance between Fire and Target (L) = 30 ft

1 f1

- Vertical Distance of Target from Ground Level (H = H ) = 10 ft

w

- Wind Speed or Velocity (u ) = 700 ft/min

- Select Fuel Type: select Heptane from the combo box

Note: When Heptane is selected, its thermal properties are automatically selected

from the table and entered in the corresponding input cells.

Results

Radiation Model Radiant Heat Flux*

 kW/m (Btu/ft -sec) 2 2

Solid Flame 4.06 (0.36)

*spreadsheet calculations attached on next page
J-53

Spreadsheet Calculations

FDT : 05.2_Heat_Flux_Calculations_Wind.xls (Solid Flame 2) s

CHAPTER 5. ESTIMATING RADIANT HEATFLUXFROM FIRE TO A TARGET 

FUEL ABOVE GROUND LEVEL IN PRESENCE OF IMND (TILTED FLAME) 

SOLID FLAME RADIATION MODEL 

Version 1805.0 

Th TOI.)Wiig ca• l 1.1\b" Utili at~ 1U l<t:ll.1tm ~atTIU 1'1"0111 a po0 1111e b a t.119~tr.~ llt1U pi?$~ 10: OTWIUI. 

Th p u pOH OTUt cat:II.'IOH t to 1JII a' 1U I<Hil'IOH 1J<tUIII ~d 11"0111 a IH Qltg l <tUa'( b a t.119~t 

~ lpO$ U)Hd $OI•H d~ tu ~ 1'1"0111 1u n e abwe grou d I: vel b deUDII IH rru coularv •;~•u " a•e lt;e ., " pre' e 10: ot wltd. 

P~tram ~tHt In YEllOWCEllS 11n BlUr~d b j' Ul~ UtH . 

Pllrlllfl ~tHI In G REEII C EllS ar~ Autom a1cally S& H~d TOifl Ul~ DRO P 00\AJII f.1Etl U tor tu f\l$1 h iHUd . 

. :..IIH I:4eqtUtOI1>1tVa iH$ <II? a• ll.'l'd b ( 1U $pl?<ld$•Ht<Ud ba>ed 0 1 ll<th in d II 1U ltp lt 

para"H' " · n t $preadaHt t pr ~~d <Ud u c ue to <WJo•:t e no" dH b a wrotg e t1rV 11 a o: II . 

Th C'<lpUIII U e II UP,~ $•O.tl be IHdbeDre <II <U<tl($1$ 1$1ll<lde. 

E11'ecUJe HeatofCCtiiiH$0H Off t e I ..) 

E111 pU~ tl•t ;J PJ 

FH 1.:..1ea 0 1 Dl:e A lea ,:..till<) 

Dtt.'no: betNeu Fle a •d Taget(l) 

W rttal 0~ tl•ce OTTalget'ftOIII G lOU d l et.te I (H· • H,) 

IN . d Speed 01 Ye td'{ (' ..;, 

.:..mb• •tAll Tempe 1.'11111~ (r,) 

G l<f.!lt.1tb•ai .:..CC:el? 1aU,. @) 

.:..mb• •tAll De "ltf (P,) 

THERMAL PROPERTIES OA TA 

BURIIIIIG RATE DATA FOR FUELS 

Calculate 

9.81 11\kt c' 

1.18 tglll 

1.& hi ~ 

S.IHII\ 

, ..... 11\ ( 

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J-54

ESTif.1ATIU:> RADIATWE HEAT FLUX TO A TARGET FUEL Ill PRES EIICE OFWIIIO 

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J-55

Disti'llcefrom Center of the Pool Fire to Edge of the Target CalcUction 

R=L+ r= 9.91 m 

Where R = d5tance from center of the pool fire to edge of the target (m) 

L= D5tance beblueen Fire and Target 

r = pool fire radius (m) 

Heel Release Rete Calc:ulction 

Q = m''iLH ~. (1· e"'"')A.u ... 

Where 

Q= 

Q =pool fire heat release rate (kW) 

m" =mass burninQ raW of fuel per unit surface area (lq:r'm2-sec) 

lLH ~ = effective heat of combustion of fuel(kJo1<g) 

~~o.<~ = surface area of pool fire (area involved in vaporization) (m2

) 

k P = empirical constant ( m ·) 

D =diameter of pool1ire (diameter involved in vaporization, circular pool is assumed) (m) 

6828.38 kW 

Pool Fire Flame Height Calc:ulction 

H, =55 D (m''/p,. v(g D))1w (if).o :· 

Where Ho = flem height (m) 

m"= mass burning raW offuel(kghn"-sec) 

D =pool fire diameter (m) 

p,. =ambient air density(k9"m:t) 

g = gravitational acceleration (mlsec'J) 

u" = nondimensional wind velocio/ 

Nondi mensional \Mn::l \kloc:ity Calc:ulction 

u" = uJ(g m'' D/p ~ · -:. 

Where u" = nondimensional wind velocio/ 

u .. =wind velocio/(mlsec) 

g = gravitational acceleration (mlsec'J) 

m" ' =mass burning raW offuel(kghn -sec) 

D =pool fire diameter (m) 

p,. =ambient air density(k9"m:t) 

u" = uJ(g m'' D/p ~ · -:. 

u"= 

Ho =55 D (m''/p .• (vg D))u11 r (if)"' 'J' 

H,= 

3270 

5.11 m 
J-56

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J-57

Problem J-8

Problem Statement

Consider a compartment that has been insulated with 1.27 cm (1⁄2 in) of gypsum board, wallboard

(S142M). If a pool fire scenario arises with a heat flux of 75 kW/m , what will be the ignition time of 2

the gypsum board?

Solution

Purpose:

(1) Calculate the ignition time of Gypsum Board, Wallboard (S142M) for the given

conditions.

Assumptions:

(1) The material is infinitely thick.

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 06_Ignition_Time_Calculations.xls (select Ignition_Time _Calculations1)

FDT Input Parameters: s

Enter the following parameters in the spreadsheet (values only):

-Exposure or External Radiative Heat Flux to Target Fuel = 75 kW/m2

-Select Material: select Gypsum Board, Wallboard (S142M) from the combo box

Note: When Gypsum Board, Wallboard (S142M) is selected, its thermal properties

are automatically selected from the table and entered in the corresponding input cells.

Results

Calculation Method Ignition Time*

igt (min)

Mikkola and Wichmann 0.34 min

Quintiere and Harkleroad 0.20 min

Janssens 0.86 min

*spreadsheet calculations attached on next page
J-58

Spreadsheet Calculations

FDT : 06_Ignition_Time_Calculations.xls (Ignition_Time _Calculations1) s

CHAPTER 6. ESTIMATING THE IGNITION TIME OF AT ARGET FUEL EXPOSED TO A 

CONSTANT RADIATIVE HEAT FLUX 

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J-59

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THERr.tAll Y THICK MATERIALS "'*'-.,. ~1r:.m-w• .,_b't_,.,.,..!l<>'.,.,..h ... .,..,.~.-:.u..rt~·=~ -t 

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J-60

Problem J-9

Problem Statement

A 75.0-liter (20-gallon) trash bag exposure fire source is located 3.0 m (10.0 ft) beneath a horizontal

cable tray. Assume that the trash fire ignites an area of approximately 1.0 m (11.0 ft ) of the cable 2 2

tray, and the cables in the tray are IEEE-383-qualified XPE/FRXPE cables. Compute the full-scale

HRR, of the XPE/FRXPE cable insulation. The bench scale HRR of the XPE/FRXPE

is 475 kW/m .

2

Solution

Purpose:

(1) Calculate the full-scale HRR of the XPE/FRXPE for the given scenario.

Assumptions:

(1) Lee’s correlation is valid for this fire scenario.

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 07_Cable_HRR_Calculations.xls

FDT Input Parameters: s

Enter the following parameters in the spreadsheet (values only):

f

-Exposure Cable Tray Burning Area (A ) = 11 ft2

-Select Cable Typel: select XPE/FRXPE from the combo box

Note: When XPE/FRXPE is selected, its thermal properties are automatically

selected from the table and entered in the corresponding input cells.

Results

Cable Insulation Full Scale

HRR

kW (Btu/sec)

XPE/FRXPE 218 (207)

*spreadsheet calculations attached on next page.
J-61

Spreadsheet Calculations

FDT : 07_Cable_HRR_Calculations.xls s

CHAPTER 7. ESTIMATING THE FULL-SCALE HEAT RELEASE RATE OF A 

CABLE TRAY FIRE 

Version 1805.0 

Th t• uca• •l.1tb"Htlllate 1u ntkcal: cabl! trav hatr~l:aH ta,. 

Pilrlllflt'n ln YEllOWCEllS ilr$ Bl 'r$d bj' Ult Ut U. 

Pilrlllfl t'r' In G REEII CEll S llrt AutomaUeaiiJ' h iHUd trom 1ht DROP OOVVII t.1EIIU tor Ult O.bl& h iHUd . 

. .:. IIHI:taqiUtOI1>1tt.t a iH$ al~ catU.'I'd by1U pl~<ld hHaad baad oa V<IIH$ p~ M!d II ~ " P't 

para•"&' " · n a; $preao; •Htl$ pr ~Wd aut $&CI.: to <WJotl & " " " <IH b a wroag u1tv 11 a c&ll('). 

Th c•aptH II U & II UP,~ $ •o.tl be le<t:IIWble <II <U<t\1$ ~ 1$ m <t:l&. 

INPUT PARAMETERS 

Cabl! 6uc•-scat HR R \O ~ 

ExpoHd n 'o' .:..rea (t.ugu x v·v.:tU) on m 119 Cab I: Trar ' '".) 

HEAT RELEASE RATE DATA FOR CABLE TRAY FIRE 

BEIIC H4CALE HRR Of CABLE TRAY FIRE 

Cabl! T\t)e 6uc•-scat HR R Select Ca~ e T '\lee 

pu Ualf•,or .:..rea (l x V\1

) 

a·t. ;J:\N,fll j k"¢f<Pcu o ~ a·eu • .n\5! &a c:.o1 

•:1 PE 107 1 

P EIPVC ... XPEIFRXP E ns 

P EIPVC 395 

P EIPVC 359 

PE /II >Ie ~ 3Sl 

PE. PP.CI.S.PE 345 

P EIPVC 312 

PE /II >Ie ~ 302 

PE. PP.CI.S.PE 299 

PE. PP.CI.S.PE 27 I 

FRXPE.C lS.PE 258 

P E. II'{.,_IPVC, II(.H 231 

P E. II'{.,_JPVC, II(.H 2 18 

XPE,CIS .PE 20 ! 

s n:oH . gh" bratl.asbubs 182 

XPE1XPE 078 

PE. PP.CI.S.PE 077 

s n:oH . \Ih$$ bratl 128 n.,.,. •• UHrSpec lnd Va" e E•~r lt ~ 

ft.~IN~:·('~ ' .=i'N.«~.=:,.";"."t;.l'l\ :1' /";'If 1.'~~ ?,4{#:.:-r.« 

Calculate 

~ p~ Ul~n Oick on ~c11 n 
J-62

E STIMATIIIG FULL-SCALE CABLE TRAY HEAT RELEASE RATE ~~ 't<NY.~: s?P=Hmd>.-....'\ C(F)"("/>i'<:~c..-r:.:>n ~~~r(J, " adl'OO!:).\l'; Fl:\IC ;to XI. 

Q,,.: 0.46 ~a A 

mere Q,,. = cabletrayfull-scale HRR (kVll) 

Otn•= cable nybench-scale HRR (kVll) 

A= exposed 1oor area Qength x wi4h)of bumilg cable ny(m") 

Heat ~lease Rate Calculaticn 

01,.= 0.46 Ot. A 

emu¥ 

The abot@ calculations are based on princjlles developed in the SFPE Handbook of Fire Protection 

&IQineerinQ, 3ftl 6:1ition, 2002. 

C31culalions are based on cenain assurrptions and has inherent linitalions. The results of such 

calculations mayormaynot have reasonable predictit@ capabilities i:lr a given sirualion, and should 

only be interpreted by an infonned user. 

!Wlough each calculation in the spreadsheet has been veriied with the results of hand calculation, 

there is no absolute guarantee of1he accuracyoflhese calculations. 

AlyquestDns, comments, concerns. and suggestions, orto repon an error(s) in the spreadsheet, 

please send an email to nxi@lro.govormxs3@JlroQOV. 
J-63

Problem J-10

Problem Statement

Est p(centerline) imate the maximum plume temperature (T ) at the ceiling of a 6.0-m (20.0-ft) high

compartment above a 1,420 kW fire involving a 11⁄2 ft high stack of wood pallets in a 0.92 m2

(10.0 ft ) pallet area. Assume that the ambient temperature is 25 °C (77 °F). 2

Solution

Purpose:

(1) Estimate the maximum plume temperature for the given fire scenario.

Assumptions:

(1) All heat is released at a point.

(2) Buoyant forces are more significant than momentum forces.

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 09_Plume_Temperature_Calculations.xls

FDT Input Parameters: s

Enter the following parameters in the spreadsheet (values only):

-Heat Release Rate = 1,420 kW

-Distance from the Top of the Fuel to the Ceiling (z) = 20 ft

-Area of Combustible Fuel = 10 ft2

Results

Heat Release Rate

(kW)

Plume Centerline

Temperature

Tp(centerline)

°C (°F)

1,420 164 (328) 

*spreadsheet calculations attached on next page.
J-64

Spreadsheet Calculations

FDT : 09_Plume_Temperature_Calculations.xls s

CHAPTERS. ESTIMATING CENTERLINE TEMPERATURE OF A 

BUOYANT FIRE PLUME 

Version 1805.0 

The follcwing calculations estimate the centerline plume temperature in a compartmenttire. 

Per a meters should be specifie::l ONLY IN THE YELLOW INPUT PARAMETER BOXES. 

All subsequent output values are calculated by the spreadsheet and based on values specified in the input 

parameters. This spreadsheet is pro~cted and secure to avoid errors due to a wrong entry in a cell(s). 

The chap~r in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

Heat Release Rate of the Fire (Q) 142000 kW 

Elevation Above the Fire Source (z) 

Area of Combustible Fuei(A:) 

AmbientAir Temperature (T~) 

AMBIENT CONDITIONS 

Specific HeatofAir(C\>) 

AmbientAir Density(P~ 

Acceleration of Gravity(g) 

Convective Heat Release Fraction (1c) 

2000 t 

1000 t 

7700. F 

Calculate 

1 DO k.Jil<g·K 

1.18 kghn:t 

9.81 mlsec2 

0.70 

Note: Air densi~ will automatically correct with Ambient Air Temperature (T~ Input 

ESTIMATING PLUME CENTERLINE TEMPERATURE 'li I? •o: PE.'·f cbook. OX' .=t~ !Oi?\.r 'f Eig',:'"'<¥1'iiG J "' r~\'f. 2002. Pil{? 2- 0. 

Where J> n•ll~/ = plume centerline temperature ( 0C) 

Oc =convective portion of the heat release raW (kW) 

r~= ambient air Wmper ature (K) 

g = acceleration of gravity(m/secl 

cto =specific heat of air (kJA< g-K) 

~=ambient air density(k9"m1 

z= distance from the top of the fuel package to the ceiling (m) 

zo= hypotheticalvirtual origin of the fire (m) 

con-.ectlve Hea Release Rate Calc:ulctlon 

Oc=1c Q 

Where Oc =convective portion of the heat release raW (kW) 

Q = heat release raW of the fire (kW) 

1c = convective heat release fraction 

Oc= 994 kW 

Fire Diameter Calculction 

A:=nDZ/4 

Where 

0 = >(4 AI") 

0= 

A:= area of combustible fuel (m) 

D =fire diame~r (m) 

1.09 m 

6 .10 Ill 

o.ro m· 

25.00 ~ 
J-65

HVI>Othdital Virtual Oriiin Calt ulation 

ZOID = -1.02 • 0.083 (Q"")ID 

Where 

== 

zo= 

zo= ~rtual origin ofthe fire (m) 

Q =heat release rate offire (kW) 

D =fire diameter (m) 

0.37 

0.40 m 

Cet«erline Phn.e T etll)er.tture C31t ulation 

T J> ~niNI .. )- T ~ = 9.1 (T Jg c/ ~l' 0 Qc z>) (z- 1/J) -$.') 

J> ~n~II,. -T~= 139.22 

T J> ~n~ll,_) = 437.22 K 

The above cala..llations are based on principles developed in the SFP E Handb:lok of Fire 

Protection E nqineerinq, 3f4 Edition, 2002. 

Calrulations are based on certain assumptions and have inherent limitations. The results of such 

calrulations may or may not have reasonable predictive capabilities for a given situ:rtion, and 

should only be interpreted by an informed user. 

Mhough each calculation in the spreadsheet has been verified Wth the results of hand calculation, 

there is no absolute guarantee of the aa:uracy ofthese calrulations. 

My questions, comments, concems, and suggestions, or to report an error( s) in the spreadsheet, 

please send an email to nxi@nrc.gov or mxs3@nrc.gov. 
J-66

Problem 11: Fire Scenario with Sprinkler Protection

Problem J-11

Problem Statement

A fire with = 3,000 kW occurs in a makeup pump room protected with sprinkler protection.

The sprinklers are rated at 74 °C (165 °F) [standard response bulb with RTI 235 (m-sec) and 1/2

located 3.0 m (10.0 ft) from the center of the fire source. The height from the top of the fuel

package to the ceiling is 5.5 m (18.0 ft). Determine whether the sprinklers would activate and, if so,

how long it would take for them to activate.

Solution

Purpose:

(1) Determine if the sprinklers will be activated for the given fire scenario.

(2) If the sprinkles are activated, determine how long it takes for the activation.

Assumptions:

(1) The fire is located away from walls and corners.

(2) The fire is steady state

(3) The ceiling is unconfined, unobstructed, and flat.

(4) Only convective heat transfer from the hot fire gases is considered.

(5) There is heavily obstructed overhead.

(6) The ambient temperature before the fire ignition is 70 °F

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 10_Detector_Activation_Time.xls (select Sprinkler)
J-67

FDT Input Parameters: s

Enter the following parameters in the spreadsheet (values only):

- Heat Release Rate of the Fire = 3,000 kW

- Distance from the Top of the Fuel Package to the Ceiling (H) = 18 ft

- Radial Distance from the Plume Centerline to the Sprinkler (r) = 10 ft

a

- Ambient Air Temperature (T ) = 70 °F

- Select Type of Sprinkler = select Standard response bulb from the combo box

- Select Sprinkler Classification = select Ordinary from the combo box

Note: Ordinary classification is selected because the rated value for the sprinklers

in this problem (165 °F) is within the range of temperature ratings for ordinary

sprinklers (135 °F–170 °F).

Note: When the sprinkler type and classification are selected, their respective

values are automatically selected from the table and entered in the corresponding

input cells.

Results

Sprinkler Type Sprinkler Activation Time*

activation t (min.)

Standard

response bulb

2.47

 *spreadsheet calculations attached on next page.
J-68

Spreadsheet Calculations

FDT : 10_Detector_Activation_Time.xls (Sprinkler) s

CHAPTER 10o ESTIMATING SPRINKLER RESPONSE TIME 

Ve<Sion 180So0 

The following calculations estima!Jl sprinkler acti\G1ion time. 

Parameters in YELLOW CELLS are Ertered by the User. 

Parameters in GREEN CELLS are Automatically Selectedfromthe ORO P DOWN M ENUforthe Spriri<ler Selected. 

All subsequent oUiput \Glues are calcolat»ld bythe spreadsheet and based on wlues speci1ied in the input 

parameters. This spreadsheet is protect»ld and secure to avoid errors due to a wrong entry in a cell(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

Heat Release Rate ofthe Fire (Q)(St»lady Stne) 

Sprinkler Response Time Index (RTI) 

kthmion T emper.Jture of the Sprinkler (T.,.,..,.,,..) 

Height of Ceiling above Top of Fuel (H) 

Radial Distance to the Detector (r) ""'nevermore than 0.707 or 1/2\Q oflhe li~d spacinQu 

.Anbient ~r Tempel'3ture (T,.) 

Convective Heat ~lease Rate Fraction (1,) 

r.+l = 0.56 

GEN ER 1C SPR 1NKL ER RESPONSE T 1ME 1NDEX (RT1r 

Common Sprinkler Twe Generic Response 

Time hdex(RTO(m-sec)"'' 

Select Type of Sprinkle- I standard rt •ll:onu biJb 

3000.00 t 

235 ( 

w 

IJ\" ) '<J 

165 ° 

18.0011 

10.0011 

77.00 ° 

0.70 

I Calt ulate II 

IH 

Standard response bulb 235 Scroll to desired sp-iri<lert ype then Click on sel ecti en 

Standard response link 130 

Quick response bulb 42 

Quick response link 34 

User Soeci,ed \l.ilue Enter \l.ilue . 00 

~~ "t rr.~. r.~;ylv:f ":N, O, t<?; o:t • ..v.« $ p!:r.AIN .:.rtlt.O r. .;t,..v.M hxi; - AS /.FU..,ft$. IT tr.:f:cr.a• C~H¥: or. )"("$ H¥: :m:!Er.V. ~~ 1 • Pt«c«lr(l; 

x.l:f<'«"\ o.:Jncy. M>1=h.t:<'ft:. tt;:.P;:.g 07. 

* Ncte: The actLB I temperature rating shoU d be used when the value is avail able. 

1 3.89 ·c 

S.•S III 

).OS Ill 

zsoo ·c 

<:9800 K 
J-69

E STII\I\0. TING SPRINKLER RESPONSE TilliE 

Reference: NFPA fife Protection HJndbook, 19 ~~'~ Edition, 2003, Page 3-140. 

~'"' "'"' = (RTI/(vtj ~) (In (T1..- T .)/(T1..- T .,, .. ,.)) 

Where ~,. 111.,,. = sprinkler acti11ation response time (sec) 

RTI = sprinkler response time index (m-sec) or. 

u~,= ceiling jet velocity (mlsec) 

T1.,= ceiling jet temperature ("C) 

T. =ambient air temperature ("C) 

T•"'••" =activation temperature of sprinkler ("C) 

Ceiling Jet T etnl>er<llure Calculalion 

Trw T. = 16.9 (Q l~IH ' 

Trw T. = 5.38 (QJr)m/H 

Where Trot= ceiling jet temperature ("C) 

T. = ambient air temperature ("C) 

for r/H= 0.18 

ror r/H > 0:18 

Qc = convecti11e portion of the heat release rate (k\11/) 

H = height of ceiling above top of fuel (m) 

r = radial distance from the plume centerline to the sprinkler (m) 

Convective He•• Rele<lse Rate Calcul<•ion 

Qc= :>:c Q 

Where Qc = convecti11e portion of the heat release rate (k\11/) 

Q = heat release rate of the fire (kW) 

:>:c = convecti11e heat release rate fraction 

2100 kW 

Radial Distance to Ceiling Height Ratio Calculation 

r/H = 0.56 r/H > 0.15 

T1..-T. = (5.38 (Qc/r)•213)/H 

T1~t Ta = 

Tl~t= 

76.49 

101.49 ("C) 

Ceiling Jet Velocity Calculation 

4.t= 0.96 (Q/H) ~ 

4., = (0.195 Q ~ H'":llrSJ• 

Where U~t= ceiling jet velocity (mlsec) 

Q = heat release rate of the fire (kW) 

H = height of ceiling above top of fuel (m) 

for r/H= 0.15 

for r/H > 0.15 

r = radial distance from the plume centerline to the sprinkler (m) 
J-70

Radial Dislanceto Ceiling Height Rctio Calculation 

r/H = 0.56 uH > 0.15 

'-'t•= (0.195 0111/3 Hll1/2)/r"5/6 

2.602 m/sec 

Sprinlder Actiwtion Time Calculction 

~t cn = (RTI(v'-'~~)(ln (Titl· T ~T ~tl· T4>:1t:.)l:t\)) 

The above calculations are based on principles developed in the NFPA Fire Protection Hand book 

19hEdition, 2003. Calculations are based on certain assumptions and have inherent limitations. 

The results of such calculations may or may not have reasonable predictive capabilities for a given 

situation, and should only be interpreted by an informed user. 

Anhough each calculation in the spreadsheet has been verified with the result; of hand calculation, 

there is no absolute guarantee of the accuracy of these calculations. 

Al'fl/ questions, comments, concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or mxs3@nrc.gov. 
J-71

Problem 12: Fire Scenario with Heat Detectors

Problem J-12

Problem Statement

A trash fire with an HRR of 1,000 kW occurs in a battery room protected with fixed temperature

heat detectors with an RTI of 306 (m-sec) . The distance from the top of the fuel package to the 1/2

ceiling 3.7 m (12 ft) and the radial distance from the plume center to the heat detector location is

10 activation ft. Calculate the activation time (t ) for the detectors, using listed spacing of 4.6 m (15.0 ft).

Assume that the detector activation temperature of 54 °C (128 °F), and the ambient temperature

is 20 °C (68 °F).

Solution

Purpose:

(1) Determine the response time of the fixed-temperature heat detectors for the given fire

scenario.

Assumptions:

(1) The fire is located away from walls and corners.

(2) The fire is steady state.

(3) The ceiling is unconfined, unobstructed, and flat.

(4) Only convective heat transfer from the hot fire gases is considered.

(5) There is heavily obstructed overhead.

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 10_Detector_Activation_Time.xls (select FTHDetectors)
J-72

FDT Input Parameters: s

Enter the following parameters in the spreadsheet (values only):

- Heat Release Rate of the Fire = 1,000 kW

- Radial Distance to the Detector (r) = 10 ft

- Distance from the Top of the Fuel Package to the Ceiling (H) = 12 ft

a

- Ambient Air Temperature (T ) = 68 °F

activation - Select the option button (u) for FTH detectors with T = 128 °F

- Select Detector Spacing: select 15 from the combo box

Note: activation When T and Detector Spacing are selected, their respective values

are automatically selected from the table and entered in the corresponding input

cells.

Results

Detector Type Heat Detector Activation Time

activation t (min.)

Fixed

Temperature

3.03

 *spreadsheet calculations attached on next page.
J-73

Spreadsheet Calculations

FDT : 10_Detector_Activation_Time.xls (FTHDetectors) s

CHAPTER 12. ESTIMATING HEAT DETECTOR RESPONSE TIME 

Version 19l5.0 

Th ttN gca• 'I1mH tlllab 'lt(~d,lll~latU~ hato.,ctHaCUJa1)H 1Jil . 

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INPUT PARAMETERS 

~atR~ •m fta' 01 ~ Fire (J) .P'<t:I(Stl~) 1000.00 t! 

ftadl'll OttUO: b 1U ~~cbl (I') ''Ht.t IIII I~ Gal 0 .707 11/2~ OT1U ll>'d p<t l"' 10.00 11 

.:..cu;a1m nmp~ o t11e 01Ue Fked nmpua111 te Heatoe'cto' (r,..,,..., .. ~ 128 ., 

e~cbl Rupoue nne 1u1u {P.Tb 300.00 ' 

He tJUOTCe llllgabw e Tcp OT Fie I (H) 12.00 11 

.:..111 bl? •t . .:. l TW1 ~ latU~ (r,) 77 .00 ., 

0 .70 

Calculate I 

INPUT DATA FOR ESTIMATING HEAT OETECTO R RESPONSE TIME 

Activation 

Temperature T .,w,_ 

T• 128 F Ul U~<I p<dg P,~ poU~ ThH lUI? X ,A,C1JJ<t1)H 

l'.lt! RTI II~~ O) 4i n111p~ o t11e CF> Select DetectorS~ 

10 490 128 !: !5 : . 

IS ,. 128 Scrdl to d& tlr~d ' P 

acirg 

u 1ng 11l~n 

20 lZS 128 Oick on •&l&e1on 

2S 152 128 

30 116 128 

10 ., 128 

so 72 128 

70 " 128 

UHI M! lt e E•' I V<IIH E•~• Valte 

135 F I Ul U~ p<dg P,~ poU~ TllH lUI? X .'.CUJa1)H 

l l..'ltl RTI II~~ O) 4i n•11p~ t11~ CF) Select Detector Sp acirg 

10 .. , 13S 

IS 233 13S Scrdl to d& tlr~d ' P u 1ng 11l~n 

20 165 135 Oick on •&l&e1on 

" 123 135 

30 re 135 

10 70 135 

so " 135 

70 "' 135 

$~ M! lt e E•' 1Va" e E•~• Val'e 

j;JT = 145 F 

Ul U~d p<dg Re4poUe Thle lUI? X .:.cu;a1)H 

H'lt: RTI ll~e O) .. n111oe t11~ l'Fl Select Detector Sp acirg 

10 >21 

IS 191 "' 

"' Scrdl to a~ r~d ' P u 1ng 11l~n 

20 129 

"' Oick on •&l&e1on 

" ., 30 7S "' 

10 

"' ., 

50 31 

"' 70 II "' 

UH I SI=*CM!d VaiU E•' 1Va" e E•~• "' Val'e 

)In hi 

lSOO 'C 

o:t<SOO K 
J-74

= 160 F I Ul Usred Spacing 

r(ft) T 

10 

15 

20 

25 

30 

40 

User Soeciied ~lue 

= 1 70 F I Ul Ust»ld Spacing 

r(ft) T 

10 

15 

20 

25 

30 

User Speciie d \1.31u e 

T= 196 F Ul Ust»ld Spacing 

r(ft) 

10 

15 

20 

User Speciied \1.31ue 

A 0 ' ' 

Response Time Index 

RTI(m-sec)· :r 

239 

135 

86 

59 

44 

22 

Enter Value 

Response Time Index 

RTI(m-sec) :~ 

196 

109 

64 

39 

27 

Enter Value 

Response Time Index 

RTI(m-sec) i 

119 

55 

21 

Enter Value .. 

ktiv.Jtion 

Temperature ('F) 

160 

160 

160 

160 

160 

160 

Enter~lue 

.Activ.rtion 

T empel'3lure ('f) 

170 

170 

170 

170 

170 

Enter \1.31ue 

.Activ.rtion 

T emoel'3lure ('f) 

196 

196 

196 

Enter \1.31ue A -.. 

Select Detector Spacing 

Scroll to desired spacirg then 

C I i ck on selection 

Select Detector Spacing 

Scroll to desired spacirg then 

C I i ck on selection 

Select Detector Spacing 

Scroll to desired spacirg then 

C I i ck on selection 
J-75

E STIMA TIIIG FIXED 1E lvi'E RA lURE HEAT DETECTOR RESPOIISE Tlfvl: ~~ -.,~rr.': FPA.F ~P «« r.~eo.'\ . 19'' adl'br, ~'\).\.!"~;to -:«1. 

t.'"'""''"' = ( RTV(w1.,.,(1n (T1,. • T ,.)"(T ,., • T ,. ... .,.,,.,. ) 

mere t. .... ..,., .. = detectoracthmion lime (sec) 

RTI = detector response lime index (m-sec ). :~ 

up, = ceiling jet toelocity(mJsec) 

T1,. =ceiling jet tempel'3ture (•C) 

T,. = ambient air ~mperatJJre (•C) 

T""'·""'" = activ.nion temper.Jture of detector ("C) 

Ceiling Jet Temperah.re calculation 

T ,., • T,. = 16.9 (O,j"A·f"':l 

T..-T. = 5.38 (O.k)"'IH 

mere T1

,. =ceiling jet temper.Jture (•C) 

T,. = ambient air ltlmperature (•C) 

torr.+!= 0.18 

torr.+!> 0.18 

~ =convective ponion ofthe heat release r.Jte (kVll) 

H =height of ceiling abo\<e top of fuel (m) 

r= radial distance from the plume oentertine ro the detector(m) 

Ccnvective Heat Release Rate CalcUaticn 

=l O 

mere 

a. = 

~ . con'Wcti\<e heat release r.Jte (kVll) 

Q =heat release me ofthe h (kVll) 

~ = convecti\<e heat release fraction 

700 kW 

Radal Oistarce to Ceiling Heigtt Ratio calculation 

r/H = 0.83 r/H > 0.15 

>0.15 

T,., . T,. = 

T,., . T,. = 

T,.,= 

55.16 

538 ((0<*:r'213)1H 

55.16 

80.16 ("C) 

Ceiling Jet Velocity Calculation 

u1,. = o.g6 (0.+1) >~ 

u1,. = (0.1g5 a·"j l>'ll 

mere Up, = ceiling jet toelocity(mJsec) 

Q =heat release r.m ofthe h (kVll) 

<0.15 

H =height of ceiling abo toe top of fuel (m) 

torr .+I= 0.15 

torr .+I> 0.15 

r= radial distance from the plume centertine to the detector(m) 

153.46 
J-76

Radal Distarce to Ceiling Heigtt Ratio calculation 

r/H = 0.83 r/H > 0.15 

u1,. = (0.1g5 0"1.0 H"1/2)t"(5/6) 

u1,. = 1 A73 ml.sec 

Detector Activation Time CalcUaticn 

t,.., .. ,.,,., = ( RTV(w1, )) On (T1,. • T,Y(T ,., • """""'' ) 

IIOTE: tft,,0 , .,.., ton = "11UM'" Detector does n<lt M tivate 

The abot@ calco IRons are based on principles de t@lope d in 1h e N F PA Fire Protection I-bn dbook 1g" 6:1ition, 

2003. Calcol31ions are based on cenain assumptions and hat@ inherent limimtions. 

The results of such calculations mayor may not have reasonable predictive capabilities for a git@n situation, 

and should only be interpre~d by an inimned user. 

Plthough each calcul31ion in 1he spreadsheet has been t@riied with 1he results of hand calcul31ion, 

there is no absolu~ guarantee ofthe accuracyofthese calcul31ions. 

Pnyquestions, comments, concerns. and suggestions, or to repon an error(s) in 1he spreadsheet, 

please send an email10 nxi@JlroQovormxs3@JlroQOV. 
J-77

Problem J-13

Problem Statement

Calculate the HRR necessary for flashover and the post-flashover temperature in a long

access corridor that is 30.5 m long x 5.5 m wide x 3.0 m high (100.0 ft long x 18.0 ft wide x 10.0 ft

high), with an opening that is 0.91 m (3.0 ft) wide x 2.5 m (8.0 ft) high. Assume that corridor

boundary material is 15 cm (6 in) thick concrete.

Solution

Purpose:

(1) Determine the HRR necessary for flashover and the post-flashover temperature for the

given compartment

Assumptions:

(1) Natural Ventilation.

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 13_Compartment_Flashover_Calculations.xls

select Flashover-HRR to calculate the HRR for flashover

select Post_Flashover_Temperature to calculate the post-flashover temperature

FDT Input Parameters: s

Enter the following parameters in both spreadsheets (values only):

c

- Compartment Width (w ) = 18 ft

c

- Compartment Length (l ) = 100 ft

c

- Compartment Height (h ) = 10 ft

v

- Vent Width (w ) = 3 ft

v

- Vent Height (h ) = 8 ft

- Interior Lining Thickness (*) = 6 in (Flashover-HRR only)

- Select Material: select Concrete from the combo box (Flashover-HRR only)

Note: When Concrete is selected in Flashover-HRR spreadsheet, its respective

properties are automatically selected from the table and entered in the

corresponding input yellow cells.

Results

Post-Flashover

Temperature

TPFO(max)

°C (°F)

Flashover HRR

 kW (Btu/sec)

Method of Law Method of MQH Method of Babrauskas Method of Thomas

478 (892) 2,739 (2,596) 2,611 (2,475) 5,618 (5,325)

*spreadsheet calculations attached on next page
J-78

Spreadsheet Calculations

FDT : 13_Compartment_Flashover_Calculations.xls (Post_Flashover_Temperature) s

CHAPTER 13. PREDICTING COMPARTMENT POST-FLASHOVER 

TEMPERATURE 

v..-sion 1805.0 

The bllo wing calculations estimate the compartment post· flashotte rtempel'3ture. 

Parameters in YELLOW CELLS are Ertered by the User. 

All subsequent output wlues are calcolat»ld by1he spreadsheet and based on wlues specified in the input 

parame~rs. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a oell(s). 

The chapter in 1he NUREG should be read before an analysis is made. 

Compartment VlAd1h (w .. ) 18.0011 

Compartment Length 0.) 100.0011 

Compartment Height (h.) 10.0011 

\knt Width (w,.) 3.0011 

\knt Height (h ) 8.0011 

Calt ulate 

PREDICTIIIG COIYI'ARTIYI:IIT POST-FLASHOVER TEMPERATURE 

METHOD OF MARGARET LAW 't1~n2 s?P= H~">:>.I. « F:~l" «~-t:M=n;t~f'l;f, 3 " adl'br, ~'\)::, P:lt;~e :t-1<13. 

T'-'10•"'""• = 6000 (1· e .c ·n)/(\j(l) 

Where 

Where 

T ~10 .~ .... = maxirru m companment post· flasho\ler tempel'3tl.l re (•C) 

n = ventilation factor 

O= (A ·A)/A (""") 

S.o&;+ 111 

XI.0$111 

).04 hi 

0 .9 1+111 

Z.+:i* 111 

A= total area ofthe compartment enclosing surface boundaries excluding area oft@nt openings (m") 

A · = area oft@ntilation opening (m") 

~ =height of ventilation opening (m) 

Area of Vertilation Opening CalcUaticn 

A= (w") (h.,) 

Where A · = area oft@ntilation opening (m") 

~ =vent width (m) 

h., = t@nt height (m) 

223 mll 

Area of Compartmert Enclosirg Suface Bcundaries 

A= ~(w x IJ + 2(h. x wJ +2(h. x IJ]· A 

mere Ar =total area ofthe compartment enclosing surface boundaries excluding area oft@nt openings (m") 

w,. =compartment width (m) 

1,. = compartment length (m) 

h,. =compartment height (m) 

A, = area oft@ntilation opening (m") 

551.47 m" 

Ventilation Factor Calculation 

O= (A· A)/A("".,) 

Where 

0= 

u = ventllallon tactor 

A= total area ofthe compartment enclosing surface boundaries excluding area oft@nt openings (m") 

A · = area oft@ntilation opening (m") 

h., = t@nt height (m) 

157.75 m .:~ 

Compartment Post· ~ rover Temperature calculation 

~·tO·,...,, = 6000 (1. e )/(\j(l) 

l!IT,m21,, .. "' .,=:.._ _ _:4"'7'-'7.7!.!1_'"-C----"89cc18e>8c.'.!:.F ___ _,III 1-1.@!1$1 
J-79

The above calculations are based on principles developed in the SFPE Handbook of Fire 

Protection Engineering, 3f4 Edition, 2002. 

Calrulations are based on certain assumptions and have inherent limitations. The results of 

such calculations may or may not have reasonable predictive capabilities for a given situation, 

and should only be interpreted by an informed user . 

.AJthough each calrulation in the spreadsheet has been veri1ied Wth the results of hand 

calculation, there is no absolute guarantee ofthe acruracy ofthese calrulations. 

My questions, comments, concerns, and suggestions, or to report an error(s) in the 

spreadsheets, please send an em ail to nxi@nrc.gov or mxs3@nrc.gov. 
J-80

FDT : 13_Compartment_Flashover_Calculations.xls (Flashover-HRR) s

CHAPTER 13. PREDICTING COMPARTMENTFLASHOVER HEAT RELEASE RATE 

Version 1805.0 

Th fOI.)Wiig ca• 'IO,_ $ 1Jil a' 1U Ill" .... Ull hat I~ <16~ 1<1, I~ IUI ~d to Q;llllp<t11111Ut 'IL. O!J~I. 

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Pllrlllfl $'rl In G REEII CEllS ilr$ AUtolflll11CIIIIJ' h iHUd fi'OIQ 1U DROP OOVVII f.1E IIU for 1ll$ t.1 ~ter l h iHUd . 

. :. II :<$ ~q iUt I1j lt lt U al~ cat:l 1.1t~d by ~ pl~<ld$ •Htaul b.'IHd o • tJ<tltH p~ ifl?d II ~ " Pit 

p<n<llll$' " · n t ' P'""' ' ' Ht ~ p1W.c'd aut • 1e b atio•:t eno" dH b a w1019 e 11J>{ 11 a o: tl(') . 

Th c•aptH IIIU IIUREG $. 0Hibe teadl=*fOie <U <U<tlf$1$ ~ ma\le. 

COIII \.'U111 UtV"V.:IQ ;, ~ 

COIIIP,'II111 Ut '* l gt• (I;) 

COIIIP,'U111 ut HH;JU (• c) 

VutV">H:IU ;;.N0 

w ltH e•;~ •t ~ 

''''bl lllllg TU:tae" @) 

"' lbllllllg Th Dll<tiCOid i CUJit{ ;J:) 

THERMAL PROP ERTlE$ OATA 

l.latHI.'II Th hi a iCOUIICUJit{ 

I; f;V\1/hl-1\i 

.0:..1111'1111111 ll ) 0 2 00 

StH I (OS~ CabO I) 0.054 

CO I~' 0.0016 

W :t; 0.0008 

Gl.'l$$ Pl.'l' 0.00076 

:t.CO I~b U)ct; 0.00073 

Gypnm &oar.l 0.00017 

PI('A'OOd 0.00012 

Fl:.e rlu lla1JH &oard 0.0005 3 

c • !Jbc..'lrd 0.000 IS 

.O:..Ha~d CO I~' 0.00026 

PI.U~ d)O<Ifd 0.00016 

c atlm 1••~' &oard 0.00013 

.:..11m11a rr•~' & to::•: 0.000" 

Gl.'l$$ Fb~I U 11.'11JH 0.000037 

Eq;.; IOHI ($t{IU~ 0.000034 

UH ~;.e ln d ll ~ El' r v a ru 

~-.~~~: «e J . J.M::<-. Prn::'*;«S,-:r;o.'<-r •• . 

Select Material 

M"l" t H Scroll b d& r~d m11~tlill 1h~n Click on •&l&c11on 

:t'lffll, ~'\'C l":ct Zi <>. 

100.0011 

18.0011 

10.0011 

3.00 11 

8.00 11 

6.00 in 

0.0016 \'Iol ·l~ 

)),0$111 

S.•SIII 

).04111 

O.SI•III 
J-81

PREDICTIIIG FlASHOVER HEAT RELEASE RATE 

METHOD OF McCAFFREY, QUIIITIERE, AIID HARKLEROAD {MQH) ~-.,~rr;,;$/=l" H:Ird»c. ('(t=l'f:> l"UC< _-t v. r.g, 3"' adl' v, ~'\):Z, l"~ )> X\:. 

Q,o= 610 "((>• A A·(>lh )) 

mere 0 10 =heat release r.ne necessary for 1ashover (kVll) 

~ = e~cti\<e heattrans~rcoeflcient (kWhn:t·K) 

A =total area of1he corrparment endosing surbce boundaries e:mluding area of vent openings (m") 

A·= area of ventilation opening (m") 

h·: =height ohentilation opening (m) 

Heat Transfer Coefficiert Calculation 

~., = k/6 A ssuningthat ccmpartment has been heatedthoro~.ghly befcre flashover, i.e., t > t ... 

mere ~., = ef'!cti\<e heattrans~rcoeflcient (kWhn"·K) 

k =interior lininQ 1hennal conductiWv(kVllhn·K) 

6 =interior lininQ thickness (m) 

0010 kWAn' ·K 

Area d Ventilaticn Openirg C<llculaticn 

A·= (W·•)(Ih ) 

mere A·= area of ventilation opening (m') 

w ... = toent width (m) 

h·: =vent height (m) 

2.23 m" 

Area d Ccmpartment EnclosinA Surface Bcundaries 

A= [2(w. x l.)+2(h. xw.)+2(h. x l.))· A· 

mere 

A= 

A = 10tal area of1he corrparmeM endosing surDce boundaries e:mluding area ofveM openings (m'') 

w .. = companmeM width (m) 

k = corrparmeM length (m) 

~ = comparment height (m) 

A·= area ofveMilalion opening (m'') 

551A7 m:.-

Minimun Heat ~lease Ratefcr Flash:lver 

~o = 610 
J-82

METHOD OF BABRAUSKAS 

~'tl~rr:~ :SJ=I"= H:Ird»c.\ ('(FII'l" ~"T v. r.Q, f" &lll:n , . P~H ~IS• . 

Oto = 750 A .. (\tl,.) 

mere 010 =heat release r.ne necessary for 1ashover (kVll) 

A·= area ofveMilalion opening (m') 

h., = height ohentilation opening (m) 

Minimun Heat ~lease Ratefcr Flash:lver 

0 = 750 A .. (\tl,.) 

METHOD OF THOMAS 

~'t•~rr:~ :SFI"= H:Ird»c.\ ('(FII'l" ~"T v. r.Q, f" &lll:n , . P~H ~ISO . 

mere 010 =heat release r.ne necessary for 1ashover (kVll) 

A =total area of1he corrpartment endosing surtlce boundaries e:mluding area of vent openings (m') 

A·= area of ventilation opening (m') 

h., = height ohentilation opening (m) 

Minimun Heat ~lease Ratefcr Flash:lver 

Oto= 7.8A, + 

USKAS 

I 

The abotte calcola1ions are based on principles developed in the SFPE Handbook of Fire 

Protection Blgineering, 3"' 6:1ition, 2002. 

Calwlalions are based on oel'13in assumptions and have inherent limitations. The results 

of such calculations mayor may not ha'W reasonable predictive capabilities for a gi'Wn 

situation, and should only be int»lrpre~d by an ini:lnned user. 

Plthough each calculation in 1he spreadsheet has been verified with the results of hand 

calculation, there is no absolute guarantee ofthe accuracyofthese calculations. 

Alyquestions, comments, concerns. and suggeSiions. or10 repon an error(s) in 1he 

spreadsheets, please send an email10 nxi@JlroQovormxs3@lroQOV. 
J-83

Problem J-14

Problem Statement

Consider a closed compartment in a facility (a pump room) 2.75 m wide x 2.75 m long x 3.7 m high

c c c

(9.0 ft wide x 9.0 ft long x 12 ft high) (w x l x h ). A fire starts with a constant power of 75 kW.

Estimate the pressure increase attributable to the expansion of gases after 15 seconds.

Solution

Purpose:

(1) Estimate the pressure rise in the compartment at 15 seconds after ignition.

Assumptions:

(1) The energy release rate is constant.

(2) The mass rate of the fuel is neglected in the conversion of mass.

(3) The specific heat is constant with temperature.

(4) The hydrostatic pressure difference over the height of the compartment is negligible

compared to the dynamic pressure.

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 14_Compartment_Over_Pressure_Calculations.xls

FDT Input Parameters: s

Enter the following parameters in the spreadsheet (values only):

c

- Compartment Width (w ) = 9 ft

c

- Compartment Length (l ) = 9 ft

c

- Compartment Height (h ) = 12 ft

- Fire Heat Release Rate = 75 kW

- Time After Ignition (t) = 15 sec

Results

Pressure Rise* 16.53 kPa (2.40 psi)

*spreadsheet calculations attached on next page
J-84

Spreadsheet Calculations

FDT : 14_Compartment_Over_Pressure_Calculations.xls s

CHAPTER 14. ESTIMAllNG PRESSURE RISE DUE TO A FIRE IN A 

CLOSED COMPARTMENT 

V..-sioo> 180S.O 

The follcming calcolations estimate the pressure rise in a companment d.Je to 're and corrbustion. 

Parameters in YELLOW CELLS are Ent~ed by the User. 

~I subsequent oUiput wlues n calculated bythe sp-eadsheet and based on wlues specified in the input 

parameters. This spreadsheet is protect»ld and secure to avoid errors due to a wrong entryin a cell(s). 

The cha~r in 1he NU REG guide should be read before an analy;is is made. 

INPUT PARAMETERS 

COMPARTMENT INFORMATION 

Companment VlAdth (w ) 9.0011 

Comparment Length 0.) 9.0011 

Companment Height (h ) 12.0011 

Fi"e Heat Release Rate (Q) 75.00 •:'.<\' 

Time ater lgrition t\) 15.00 

Anbient Air T '" empemure (T,.) 77.00 ' f 

Calt ulate 

AMBIENT CONOrTIONS 

lritial PtrmspheOO Pressure (P,.) 

Specific Heat of Atr a Constant \.tlume (c·:) 

14.701p" 

L.._ ___ ...:.O·c:.7:.J1•:,1l:oJ·K 

(Ncte: '-'lues of c-: ranges from 0.71 to 0.85 k.IA<g·k) 

.Anbient Air Oensity(p.) 1 1sl~ .. w. 

tbte: Pir density will autom31icalycorrect with .Anbient Ar Temper.rure (T,.) Input 

lvl: lHOD OF KARLSSOII AIID QUIIITIERE 

(P • P,.) I P .. = Ot /(\/ p .• c, T,.) 

P =compartment pressure due 10 fire and combustion (kPa) 

P,. =initial atmospheric pressure (kPa) 

Q = heat release me ofthe fire (kVll) 

t=time aterigniticn (sec) 

V= compartment wlume (m 1 

p .• = ambient dE'f'lsity(kg.tn 1 c: = specific heat of air at ccnmnt volume (k.IA<g·K) 

T,. = arrbient air ltlmperaure (K) 

Compartmert Vdune C<llculaticn 

V= w .. xl .. xh .. 

Where 

V= 

V= wlume of the ccmpartment (m 1 w .. = corrpanment width (m) 

k = compartment length (m) 

h" = compartment height (m) 

27.52 m:t 

Pressure ~se in Ccmpartment 

(P· /P,. = Ot/(Vp,.c,T,.) 

(P·P,.)IP,.= 0.163 attn 

Z.7• •to 

2.7. hi 

);;._;hi 

JSOO ' C 

zt<S.OO ~ 

M.lltiPI\(ng bylne atmosphenc press,lre1:" jE;1~U~1~k~"i"~gb~~~~~~~~~~~~ Gi'Ws a pressure di~rence = 
J-85

This example shows that in a very short time the pressure in a closed compartment rises to 

quite large value. 

Most buildings have leaks of some sort. The above example indicates that even though a fire 

compartment may be closed, the pressure is very rapid and V\Ould presumably lead to suffident 

leaks to prevent further pressure rise from ocrurring. We Wll use this condusion 'Y\hen dealing 

Wth pressure rises in enclosures Wth small leaks. 

The above calculations are based on prindples developed in the Enclosure Fire 0'yTlam ics. 

Calculations are based on certain assumptions and have inherent limitations. The results of 

such calrulations may or may not have reasonable predictive capabilities for a given situation, 

and should only be interpreted by an informed user . 

.AJthough each calrulation in the spreadsheet has been verified Wth the results of hand calculation, 

there is no absolute guarantee ofthe accuracy ofthese calculations. 

My questions, comments, concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to md@nrc.gov or m xs3@nrc.gov. 

~><""" ~' E'4u1 ~,;.; M~~ 

·~ Q'f' 

r'Q ::, . ~ 

~ ~ ~ . 

~" c ~ ... _ <::>" 'Y~ ~ 

l;i- )}~ ~ 1." 
J-86

Problem J-15

Problem Statement

The licensee used UL Design No. 816 to protect a number of unrestrained beams. The licensee’s

quality assurance (QA) program verified that there is 6.35 cm (21⁄2 in) thickness of fire protection

insulation on all of the beams. The size of the tested beam was W12 x 26. Determine whether the

6.35 cm (21⁄2 in) thickness of fire protection insulation is acceptable for a beam that is W8 x 13.

Solution

Purpose:

(1) Determine whether the 6.35 cm (21⁄2 in.) thickness of fire protection insulation is

acceptable for a W8 x 13 beam using the data for a W12 x 26 beam.

Assumptions:

(1) The heat transfer is one-dimensional.

(2) The analysis assumes that as the structural member heats up, structural properties

change substantially.

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 17.1_FR_Beams_Columns_Substitution_Correlation.xls (Click on Beam)

FDT Input Parameters: s

Enter the following parameters in the spreadsheet (values only):

2

- Rated Design Thickness of Beam Insulation (T ) = 2.5 in

- Select Beam with known rating for insulation thickness: select W12 x 26

- Select Beam with unknown rating for insulation thickness: select W8 x 13

Note: When beam size (e.g., W12 x 26) is selected from the combo box, its

properties are automatically selected from the table (“Data” spreadsheet) and

entered in the corresponding input yellow cells.

Results

Required Equivalent

Thickness*

 7.09 cm (2.79 in)

not appropriate

*spreadsheet calculations attached on next page

From the substitution correlation, we obtain that 6.35 cm (2.5 in.) of fire protection insulation

is not appropriate for W8 x 13 because the required thickness is more than 6.35 cm

(2.5 in.).

A similar problem can be analyzed for a column, the calculations for columns are included

in the same FDT (not shown). s 
J-87

Spreadsheet Calculations

FDT : 17.1_FR_Beams_Columns_Substitution_Correlation.xls (Beam) s

CHAPTER 17. ESTIMO.TING THICKNESS OF FIRE PROTECTION SPRAY-APPLIED 

COATING FOR STRUCTURAL STEEL BEAMS (SUBSTITUTION CORRELATION) 

Version 1805.0 

For beams protected by spray. applied protections, follcwing correlation enables substitution of one 

beam from another by varying the thickness of the fire protection insulation. 

Pcrameters in YELLOW CELLS are Entere::l bvthe User. 

Pcrameters in GREEN CELLS ere Automcticallv Selededfromthe DROP DOWN MENU fort he Beam Selecte::l. 

All subsequent output values are calculabld by the spreadsheet. and based on values specified in the input 

parameters. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a cel(s). 

The chaptl>!r in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

Rated Design Thickness of Beam Insulation (T:.:) 

Kno\60 Ins !I rti on Ratj og 

Weight of the Beam (\A/:.:) 

Heabld Perimeter of Beam (D:~) 

I !nknnoo Ins !lstjnn R[Cjng 

Weight of the Beam (Vl/·) 

HeaWd Perimeter of Beam (D·) 

SECTIONAL FACTORS FOR STEEL BEAMS 

Select the Beam Wth ~ 

rcting for insula ion thic!G'less 

I Wl2 X 26 1:-1 

f-----::-'2:::1611 ... 43.45.in 

13oo1~b1t Zlfi21n 

Select the Beam Wth • •nknnoo 

rcting for insulction thic!G'less 

J W8x 1§ lEI 

Subsclil>t 2 

(Rated Be<lm) C_.culate II 

Subscril>t 1 

(Subst~IRe Be<llll) 
J-88

ESTIMATING THICKNESS OF FIRE PROTECTION INSULATION ON UNRATED BEAM l'l:'l!r~•o: : u.,:{,* Ss <tr.c~ D..I?.:.t>. y. \.tttlm;? 1. 9~ P~;? . 

T· = ((Wi 0, +0.6)T,)'(W1/D· + 0.6) 

Where T· =calculated thickness of fire protection insulation on unrated beam (in) 

T:r =design thickness of insulation on rated beam (in) 

W · = ~ight of beam with uri<nown insulation rating (lblft) 

W:r = ~ight of design rated beam (lblfO 

D· =heated perime~r of unrabld beam (in) 

D:r =heated perimetl>!r of the rated beam (in) 

Require:! EquiWent Thic!G'less of Fire Prote:tion Insulation on Unrate::l Beam 

T· = 

The above calculations are based on method developed in the UL Fire Resistance 

Directory. Volume 1, 1995. Calculations are based on certain assumptions and have inherent 

limitations. The results of such calculations may or may not have reasonable 

predictive capabilities for a given sib.Jation, and should only be in~rpre~d by an 

informed user. 

Although each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolute guaran~e of the accuracy of these calculations. 

Any questions. comments, concerns, and suggestions, or to report an error(s) in the spreadsheet 

please send an email to nxi@nrc.gov or rro<:s3@uc.gov. 
J-89

Problem J-16

Problem Statement

During a routine fire protection inspection, an NRC inspector discovers a significant oil leak in a

station air compressor in an access corridor in the fuel building. It is important to determine

whether a fire involving a 76.0-liter (20.0-gallon) spill of lubricating oil from a compressor could

damage the safety-related cable tray and electrical cabinet in the corridor. The compressor is on

a pedestal approximately (1.0 ft) above floor level and has a 1.12 m (12.0 ft ) oil retention dike. 2 2

The safety-related cable trays are located 2.5 m (8.0 ft) above the corridor floor with a horizontal

distance of 1.2 m (4.0 ft) from the edge of the compressor’s oil retention dike. The horizontal

distance between the compressor oil dike and the electrical cabinet is 1.52 m (5.0 ft).

The c c access corridor has a floor area of 6.0 m wide x 4.6 m long (20 ft wide x 15 ft long) (w x l ),

c

ceiling height of 3.0 m (10.0 ft) (h ), and a single unprotected vent opening (door) that is 1.2 m wide

v v x 1.8 m high (4.0 ft wide x 6.0 ft high) (w x h ). The corridor has no forced ventilation and it is

constructed of 0.3048 m (1.0 ft) thick concrete. The corridor has a smoke and heat detection

system and a wet pipe sprinkler system. The nearest sprinkler is rated at 74 °C (165 °F) with an

RTI of 235 (m-sec) and is located 2.98 m (9.8 ft) from the center of the dike. Determine whether 1/2

there is a credible fire hazard to the safety-related cable trays and electrical cabinet. Evaluate the

hazard of the fire scenario using the following parameters:

b

(a) pool fire heat release rate, , flame height, z, and burning duration, t

g

(b) compartment hot gas layer temperature, T , as well as gas layer height z

(c) heat flux to the target (electrical cabinet) using the point source model,

(d) heat flux to the target (cable trays) using the solid-flame radiation model,

p(centerline) (e) centerline plume temperature, T

activation (f) sprinkler activation time, t

(g) HRR necessary to cause flashover,

Solution

Purpose:

(1) Determine if the given fire scenario could represent a hazard for the safety-related cable

trays and electrical cabinet.

Solution Approach:

To analyze this fire scenario, we are going to use various concepts that have been

presented individually in the NUREG. A logical approach for this type of problem is to

analyze the heat source and then its effect over the safety-related targets and fire

suppression systems. First, we are going to calculate the HRR, flame height, and the

burning duration of the pool fire (see Chapter 3) in order to determine the intensity and

geometrical characteristics of the fire. Then calculate the hot gas layer temperature and

gas layer height (see Chapter 2). Then calculate the centerline plume temperature to obtain

an estimate of the maximum temperature in the fire scenario (see Chapter 9). Then, we are

going to calculate the radiative heat flux from the pool fire to the electrical cabinet and cable

tray (see Chapter 5). After that, evaluate the activation time of the sprinkler system to

determine if the system is able to respond to the actual developed fire (see Chapter 10).

The last calculation is the required HRR for flashover (see Chapter 13). Once we get all

these values, we have to use them to evaluate the hazard of the fire scenario.
J-90

Assumptions:

(1) There is instantaneous and complete involvement of the liquid in the pool fire.

(2) The pool fire is burning in the open.

(3) The pool is circular or nearly circular.

(4) The fire is located at the center of the corridor or away from the walls.

(5) All heat is released at a point

(6) Buoyant forces are more significant than momentum forces

(7) Radiation to the surroundings can be approximated as being isotropic or emanating

from a point source (valid for point source radiation model only).

(8) Only convective heat transfer is considered for sprinkler activation.

(9) The ambient (or initial condition of the air) is at 25 °C (77 °F)

(10) The bottom of the oil retention dike is at ground level.

(11) The distance from the top of the fuel package (oil pool) to the ceiling is 10 ft, the pool

height or oil layer thickness is negligible compared to ceiling height (about 0.22 ft).

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 03_HRR_Flame_Height_Burning_Duration_Calculations.xls

(b) 02.1_Temperature_NV.xls

(c) 09_Plume_Temperature_Calculations.xls

(d) & (e) 05.1_Heat_Flux_Calculations_Wind_Free.xls (select Point Source and

Solid Flame 2 for the target cabinet and cable tray heat flux analyses,

respectively)

(f) 10_Detector_Activation_Time.xls (select Sprinkler)

(g) 13_Compartment_Flashover_Calculations.xls (select Flashover-HRR

to calculate the HRR for flashover)

FDT Input Parameters: s

Enter the following parameters in the spreadsheets (values only):

(a) 03_HRR_Flame_Height_Burning_Duration_Calculations.xls

- Fuel spill volume (V) = 20 gallons

dike - Fuel Spill Area or Dike Area (A ) = 12 ft2

- Select Fuel Type: select Lube Oil from the combo box

Note: When Lube Oil is selected, its properties are automatically selected from the

table and entered in the corresponding input cells.

Results*

Heat Release Rate

 kW (Btu/sec)

Burning Duration

b

t (min)

Pool Fire Flame Height

Hf m (ft)

Method of

Heskestad

Method of

Thomas

1,131 (1,072) 22.0 2.7 (8.85) 2.95 (9.67)

*spreadsheet calculations attached at the end of the problem
J-91

(b) 02.1_Temperature_NV.xls

c

- Compartment Width (w ) = 20 ft

c

- Compartment Length (l ) = 15 ft

c

- Compartment Height (h ) = 10 ft

v

- Vent Width (w ) = 4 ft

v

- Vent Height (h ) = 6 ft

T

- Top of Vent from Floor (V ) = 6 ft

- Interior Lining Thickness (*) = 12 in

- Heat Release Rate = 1131 kW

- Select Material: select Concrete from the combo box

Note: When Concrete is selected, its properties are automatically selected

from the table and entered in the corresponding input cells.

Results*

Time

(min)

Hot Gas Layer

Temperature

Tg °C (°F)

Gas Layer Height

z m (ft)

0 25 (77) 3.05 (10)

1 199 (389) 1.83 (6.0)

2 220 (428) 1.83 (6.0)

3 233 (452) 1.83 (6.0)

4 244 (471) 1.83 (6.0)

5 252 (486) 1.83 (6.0)

10 280 (536) 1.83 (6.0)

15 298 (568) 1.83 (6.0)

20 311 (592) 1.83 (6.0)

*spreadsheet calculations attached at the end of the problem

(c) 09_Plume_Temperature_Calculations.xls

- Heat Release Rate = 1131 kW

- Distance from the Top of the Fuel to the Ceiling (z) = 9 ft

- Area of Combustible Fuel: 12 ft2

Results*

Heat Release

Rate (kW)

Plume Centerline Temperature

Tp(centerline) °C (°F)

1,131 473 (884) 

*spreadsheet calculations attached at the end of the problem
J-92

(d) 05.1_Heat_Flux_Calculations_Wind_Free.xls

Point Source (heat flux to the electrical cabinet)

dike - Fuel Spill Area or Dike Area (A ) = 12 ft2

- Distance between Fire and Target (L) = 5 ft

- Select Fuel Type: select Lube Oil from the combo box

(e) 05.1_Heat_Flux_Calculations_Wind_Free.xls

Solid Flame 2 (heat flux to the cable tray)

dike - Fuel Spill Area or Dike Area (A ) = 12 ft2

- Distance between Fire and Target (L) = 4 ft

1 f1

- Vertical Distance of Target from Ground (H = H ) = 7 ft

- Select Fuel Type: select Lube Oil from the combo box

Note: When Lube Oil is selected, its properties are automatically selected from the

table and entered in the corresponding input cells.

Results*

Radiation Model Target Radiant Heat Flux

kW/m (Btu/ft -sec) 2 2

Point Source Electrical Cabinet 6.0 (0.53)

Solid Flame Cable Tray 13.24 (1.17)

*spreadsheet calculations attached at the end of the problem

(f) 10_Detector_Activation_Time.xls

Sprinkler

- Heat Release Rate of the Fire = 1,131 kW

- Distance from the Top of the Fuel Package to the Ceiling (H) = 9 ft

- Radial Distance from the Plume Centerline to the Sprinkler (r) = 9.8 ft

a

- Ambient Air Temperature (T ) = 77 °F

- Select Type of Sprinkler = select Standard response link from the combo box

- Select Sprinkler Classification = select Ordinary from the combo box

Note: Standard response is selected because it corresponds with the given RTI

value. Also, Ordinary classification has been selected because the rated value for

the sprinklers in this problem (165 °F) is within the range of temperature ratings for

ordinary sprinklers (135 °F–170 °F).

Results*

Sprinkler Type Sprinkler Activation Time

activation t (min.)

Standard response link 1.73

*spreadsheet calculations attached at the end of the problem
J-93

(g) 13_Compartment_Flashover_Calculations.xls

c

- Compartment Width (w ) = 20 ft

c

- Compartment Length (l ) = 15 ft

c

- Compartment Height (h ) = 10 ft

v

- Vent Width (w ) = 4 ft

v

- Vent Height (h ) = 6 ft

- Interior Lining Thickness (*) = 12 in

- Select Material: select Concrete from the combo box

Note: When Concrete is selected, its properties are automatically selected from the

table and entered in the corresponding input cells.

Results*

HRR for Flashover

 kW (Btu/sec)

Method of MQH Method of Babrauskas Method of Thomas

836 (729) 2,261 (2,143) 2,064 (1,956)

*spreadsheet calculations attached at the end of the problem

Conclusions

According to the calculations the fire could represent a hazard to the safety-related targets

(cable tray and electrical cabinets) due to the following results:

• From the pool fire analysis we obtain that the flame height is greater that the cable tray

height. That means that the flame probably will impinge upon the cable trays since the pool

is just at 4 ft from the cable tray (horizontal distance).

• The hot gas layer analysis estimates that the hot gas temperature will be over 500 °F and

almost 600 °F at 10 minutes and one (1) minute, respectively. These temperature values

are the critical temperatures for thermoplastic cables. Also the corridor will be almost filled

with smoke at one minute after the ignition, which means that the cable tray and electrical

cabinet will be rapidly exposed to the hot gas layer.

• Heat flux calculations show that the solid flame model predicts a radiant heat flux greater

than the critical heat flux for IEEE-383 qualified and unqualified cables. Also, the heat flux

to the electrical cabinet could represent a hazard for the integrity of the cabinet components.

• The HRR of the fire is very close to the HRR for flashover. Therefore, the whole corridor

could flashover. The sprinkler should activate approximately at 2 minute after the fire

development, during this time the fire should begin to be controlled. The burning time of the

pool is significantly greater than the activation time of the sprinklers; thus, a complete and

immediate extinguishment of the fire is not expected.
J-94

Spreadsheet Calculations

(a) FDT : 03_HRR_Flame_Height_Burning_Duration_Calculations.xls s

CHAPTER 3. ESTIMATING BURNING CHARACTERISTICS OF LIQUID POOL FIRE, 

HEAT RELEASE RATE, BURNING DURATION, AND FLAME HEIGHT 

Wn lon IM+$.0 11.- 1: O' rt,I O.I~ nl U IM~ 1.-1.-~ ~INoa ~ , lo.ti11V U~I Cf\ ~'ol1~0\t l'd.,\l1:f <J~I4J>od ·~· 

f'I ll ~- n VBlO'NCB le u~ 81-"4 I> ~ II . 

P~ 10 ~- n GRESI CB le ~ Alltlm11 ."t; e"~ -4 Tllm '" OFOP OO'N III.IEIIII1\lrU" Flld e"~ -4. 

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11 .. clll>~ h h IIIII ll..,. ll> ll>#:r~ ~\~~fllll ~k. 

IN Pili PABAMfifBS 

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11~ 1:rro~tr OII, II)'<IIOQ'bcn O.a>9 $ 1 ct o: ~1:rro~u lUI O.<OS ~ .'.. "'hd 01, HNo'.J' oms 39,i'OO &70 

Cl\ok OII omn .,,.., ~~. .. ~ 01 O.a>9 .. .., ~ 

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"" ~l'llll t~4 h4 ~• l>~ 

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0'·' .7 ,. 

2.1 

'2·.1 ' 

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B* ~~ 
J-95

ESTIMATING POOL FIRE HEAT RELEASE RATE 

P,Ui 1~ •o: : S ,=p E .'·f~.;cbc..W. ot ,={,* P:o lo;t ~ e.g t. tr,g , :j"' 6:1 lb •, 2002, P~~ J-25. 

Q = m"lLH ~.,, (1 • e ""0

) At...., 

Where Q =pool fire heat release rate (kW) 

nt' =mass buminQ raW of fuel per unit surface area (kWm2-sec) 

lLH ~.,, = effective heat of combustion of fuel (kJA<g) 

A= ~o. .. =surface area of pool fire (area involved in vaporization) (m2

) 

kP =empirical constant (m ·) 

D =diameter of pool1ire (diameter involved in vaporization, circular pool is assumed) (m) 

Pod Fire OiamSer Calc:ulal:ion 

~~o.. = 71()"/4 

Where At...., = surface area of pool fire (m2

) 

D =pool fire diamtl>!r (m) 

D = v( 4A. ~o../79 

D = 1.191 m 

ESTIMA liNG POOL FIRE BURNING DURATION 

(U:IH:I> Wlli tel.1t11W . tU 'll.'l>. pollt, II ~ 1J<m1HIIUOII, 1~ l'lle 

t•~a bd 

t:.=4V/7C/ v 

Where t:. =burning duration of pool fire (sec) 

V=volume of liquid(m' ) 

D =pool diameter (m) 

v = reQression rate (nv'sec) 

CalcUction for Ret=~ression Rate 

v = rrt'lp 

Where v = reQression rate (nv'sec) 

rrt'- mass burninQ rate of fuel (lq:r'm2-sec) 

P =liquid fuel densitv(lq:r'm:t) 

v = 0.000l51 nv'sec 

BurninA Duration CalcUction 

=4V.mD ' v 

ESTIMA liNG POOL FIRE FLAME HEIGHT 

lvETHOD OF HESKESTAD 

P,e'IHUO: : =PE.'·f~.i<b~;.W. oT.:i.* P:Ulo;t~'\~ S:g ll l'iig .':!" E<IIIIU, 19i't5, Pag: 2-10. 

,. Ho=D.235 Q · 1.02 D 

Where H, = pool fire flame height (m) 

Q =pool fire heat release rate (kW) 

D =pool fire diameter (m) 

Pod Fire Flame HeiQ-4 Calculation 

H1 = 0.235 r:fo • 1.02 D 
J-96

METHOD OF THOMAS 

Pi~ 't<NU: s;::p=~-..:J..('( «fbn 'n;J. "" &IIICf\ I~ P~ ~ZOO. 

H, • poolm Thill ~ h.;JU (II) 

m• • Ill aa IU Qllg "'' OT1U lp? I I I lH ltiO: <ma ;J glhl ¢) 

p,.• <llllb'"ltallm ult'{ ;J;g.hl) 

0 • p001111e II.'IIIH~ I II) 

g - grwlti1JHa cc~l? rau,. ~~ ~ 

Pool Fi r~ Flam$ Helgllt0llcula11on 

H,• 1.2 o Qll"l p,.v@ D))'"' 

!H,= 2.35 m 

Flame, HtHoht Calcul:~t.on · Summanrof Results 

C iliCUh'IUOO f.1 &1hOd 

r.1ETHOD OF HESKESTAD 

r.1 ETHOD OF THOMAS 

11 '441'4' 

ESTIMATING POOL FIRE RESULTS FOR RAND OM SIZE SPILLS USING INPUT PARAMETERS 

~:. (m 1

) let ••• r Q 1kVv1 

I 0.03 o.u !IUS 1$$$(1.4$ 

' 0.13 0.43 133.H 7Uo.21 

' (1.2$ ~0 232.U 523U$ 

" 0.$7 ~3 $77 . I$ $370. 11 

' us 0.77 J71.JI $17U+3 

' O.H o.u HU!I ~JUJ 7 ~s 0.31 ~53 7 22 ~U$ 

' 0.7J 0.37 nus 1335.05 

' UJ 1.(1$ $4$.$$ 17UJ3 

" 0.3$ U+!l UU2 1538.04 

" U+l l.IJ 10$7.11) I.UU$ 

" 1.11 1.13 II$ 1.$3 1$2$.$7 

" 1.21 1.24 22 H~ 122 I.S7 u uo 1.23 U13.U 1UU2 

" 1.$3 U$ 1414.22 IOS$.70 

" u~ 1.54 133H$ 73U2 

" 2.$2 1.72 2$57.04 U5.2 2 

" us 2.4$ 4714.03 $lUI 

" U 7 2.33 707 1.12 2 11.74 

"' 3.23 $.44 U 23.17 I SUO 

Ca i!JH : Th p lq)OH OTUI$ I<IHICtll $p ll$ ~ c •art 1$ b a•:I1U U~ I,_ ti<l llatll g 1U 

• azar.l oTraHICtll ~d ll>. Pl:aH •o' at ~ a• 'IIm ~ ttll ~ 11 baccout 

~ II CO t{O tiO I.'IOI~ TU ~ ·· ·· 1. IU~ absoqrtll TU ~ HIT<t . ~ IHI be 

9~ ~ l<l~d bl$hi<IIIVO IUII ~ $p l1$ ~ ll.'llg? al~<l $ $. 01 •:1 b~ IHd WIG Uti: Ill ~ C<IIIJH . 

If!. iii 

~ .. :o;~ .:at:ll.'ltbu are :.a~d • pill" >'"' ~tt=*d ••1u S FP E tt.'IHI:tocf; 01FII! 

PIO,ctD• E• ll e~ lll ,Zul6:111m , 19i'IS. 

a• •I.11J U a~: baad o• oHtlll a sump!J,., a1d <V~ "'~ 1: •tltlllti!J,., . ~ ~eult 

OT$1C. ca ll.10,_ $ hl<t{OI may •ot•<Ve l~ai "Ib-. ple<I.:UJe C<lX'IbltiJ!$ 'bla gl.l? ' 

$1l1a11n.a l d $•o ••:lo•l{l;.; ll'q>l! 'dbV a1 ,. ., ,~~ed ~ 1. 

.O:..IG019• ~<t • cat:U.'Itb • 1•1U p1~<t:I$ U<I $ ;.;~ ' veltn?d WIG 1U I~Uit OU<IId 

ca•: 11.10,. , IU 1: ~ •o .. :4on al.'u'~ oTQe <t:CII<t'f TQ~ e ca •l.10,. , . 

. :. .• II 1),. $, O:tiiiiiUt ,co•o: h $,a •d UgJ?$1bU,OI b leporta• e UOI{') II IU 

p1~<1 l$h~U. pl!a>~ ~ •da• elll<lllto nl@• &.g)VOIIIIX$ 3€J:• C-9)11. 

·~~ 119!!<£ . t;."- ~)'. :;,;::; <:1! ' ~ !! ~ ~ 1: 

"' ji( 

~ $ .. , ""' ·~.() ~cw 

'"'·. . • . ll: . 

H (Tt) (HHk&t tld ) ' uo 

4J~J 

$.$$ 

$.37 

.J7 

Ul 

7.$(1 

u~ 

7.33 

$.$(+ 

$.$$ 

us 

3. 11 

us 

3.53 

IUO 

II.~ 

14.53 

IUS 

13.-ll 

H (ft)(lhom a. ) I ' ... 

5.13 

$.37 

uo 

7. 1$ 

uo 

3.02 

uo 

$.?'$ 

3.07 

U$ 

U 7 

3.34 

lo.20 

10.4S 

IUS 

12.43 

15.37 

13.23 

21).2+) 
J-97

(b) FDT : 02.1_Temperature_NV.xls s

CHAPTER 2. PREDICTIIIG HOT GAS LAYER TEMPERA lURE AIID SMOKE 

LAVER HEIGHT Ill A ROOM FIRE WITH IIA lURAL VEIITILATIOII 

COMPARTMEIITWITH THERMALLY THICK/THIII BOUIIDARIES 

Version 19l5D 

~ 'bt)Witg ca• • h1J' " 011ate 1u •otg.u tr l,mpuatue <Ud ~ tr ••~ t~•t • u c•x •.: 111e. P.'ll'\'lffi$'rl In YEllOWCEllS llr$ Blter$d 11,' Ul$ UtH . 

P.'ll'\'lffi$'U In GREEII C EllS llr$ AUtomllU~II IV $$1$C'd TCffl 1l$ DROP OOWII t.1EIIU br1ll$ f.btel1ill h i$C,d . 

. O:..II bHq tt 1> tt •• ' <ue ca t:tl.~ by ~ P'~a:t> ~~ta d baad lt ' $pecrtd 11 1u ltptt j).'II.'IIIH' IL n a; $ple<t:I$•Ht ~ p1o-.~d <tHI$eCue bat.tot le IDI> (ft e b a WIOt ge 11r>{ II a 0:11('). 

n e c•ap' Jlt1U tiUR~ ' •o• t1 be JMdbe'bte at a~<lll$ 1> t ma:'". 

CCtllp.'llllM lt*/V tiQ ) 

tll~\.'l lllM It I.UgQ (I) 

CCtllp.'llllM It H! •JU ) ' 

w ttv·v•:ru ;,w';J 

utHetJ•t~ ) 

TCt) 01VUtfDIII f bOI (<If) 

''~'•" U•••gn tt:H" w 

Af,1 BIEIIT COli DrTO liS 

Sj) ~ HMt01.0:..11 i) 

;:OJIIbl!lt:...l 0U$1t{ .) 

THERMAL PROPERTIES OFCOf.1PARTf.1EIIT El t::LOS IIIG SURFACES FOR 

II~ fbi LIIIU Thnll lll ~ lttl i); pc) 

11~1·)1 Lllllg Thnlla iCOid iCUJit{ ;t.) 

11~1·)1 L1111 ~) ~ HMt@ 

11~1·)1 LIUUI OU$l\l ) 

!.00 ' 

6.00 ' 

6.00 ' 

12.00 " 

77.00!,. 

0.0016 .,_.,~m~, 

0.75 .1\Q.M. 

2,00 p'm' 

110, : . .:. l d~ Ult{ W II a lb lll a!J II{ COllect WIG ,:OJ(I bl?l V.ll n 111p~ Iatif~ (r.) lip It 

EXPERIMENTAL THERMAL PROPERTIES FOR COMMON INTERIOR LINING MATERIALS 

'·""' 11.11 

•:jlC ' c p 

ili'lV,tll .. 40 .. ~~c ;I:V'f ,III-IG ;t:J.•:o-IG f;<t.lll '\ 

.' .ltiiiiUh'l fill~) roo 0.106 OIJ>S 27 10 

S. l (OS._. Callm) 197 0.o5' 0 .165 7850 

I~' 2.9 0.0016 0 .75 2WO 

6t.:t: 1.7 ooore •• 2000 

Gl.'li$. Pl.~ 1.6 0.00076 •• 27 10 

6ttt .COICI:' 6bct 1.2 0.00073 ... 1roo 

Gy):<$ I h'l 60.'IId 0.18 0.00017 1.1 .,., PI(.,'OCd 0.16 0.00012 zs SlO 

b~l ll $11.1\b l 60.'IId 0.16 0.00053 125 210 

c ••:h o."'" 0.15 0.00015 125 ., M ta,d COICI:' 0.12 0.00026 ~ 

Pl.'li~JI».'IId 0.12 0.00016 ... "" .., c a•: tull Sttba' 6oar.l o.ore 0.00013 1.12 700 

:..l . ull Ita Sllba' U:d; o.coo 0.0001' 1 

Gl.'li$ fb~t l 1.10)1 0.0018 o.oooo:sr •• "" ~pal ~d 0\1$1/I~H 0.001 0.00003, IS "' UHI SI~ M!d ~ El,t lt ~ El' tt ~ El' lt ~ "' El,tVa iH 

' , .. 

lllllllm 

m 

.... , ... ll~m 

ll~m 

II:Jl""m 

Select Material 

Lilo:r•• ·I 

Scroll to d~ •I r~d m11 ~ 11a 111H n 

Oick tl~ ~cu n 
J-98

FIRE SPECIFICATIONS 

Fire Heat Release Rate (Q) 1131.00 •:•.:v 

Calt ulate I 

METHOD OF McCAFFREY, QUIIITIERE, AIID HARKLEROAD (MQH) ~'t•~rr:~:SFP H~-..'\ C(F ~Pi'<:~~a:.m ~nc-HN;J i" &Ui ,~. P~~ 17$ . 

Where AT11 = T 11 · T,.= upper layer gastempemure rise abot@ ambient (K) 

Q = heat release r.Jte oflhe fire (kVll) 

A· = area oft@ntilalion opening (m') 

h·: =height of ventilation opening (m) 

~ = convective heat transi!r coefficient (kW.tn :t -K) 

A =total area oflhe compartment enclosing surface boundaries e:mluding area of t@nt openilgs (m:t) 

Area d Ventilation Opening calculaticn "'= (w") (h.,) 

mere A· = area oft@ntilalion opening (m") 

Wv= vent widlh (m) 

h·: = t@nt height (m) 

A· = 2.23m" 

Thermal Penetration Time Calculation 

tp = (pc.-11<) (6D.i 

Where t 11 =thennal penemion time (sec) 

p = interior construction d ensitv (kAhn 1 c11 = in~rior construction heat capacity(k.IA<g-K) 

k =interior constructionthennal conductiWy(kWhn·K) 

6 = int:eriorconSII'\Iction thickness (m) 

26128.98 sec 

Heat Tranifer Coefficient CalcUaticn 

~ = v(kpc.t) fort< ~ or (k/6) fort> tp 

mere = heat11'3nsfercoefficient(kWhn:t·K) 

kpc = int:erDrconSII'\Iction 1hennal inertia (kWhn :t.K):t -sec 

(a thermal property of material responsible forthe me oftempemure rise) 

t =time after ignition (sec) 

See table below for results 

Area d Compartmert ErclosinA Surface Bcun::laries 

A= [2(w )+2(h xw )+2(h xlc)]·A· 

mere A =total area oflhe compartment enclosing surface boundaries e:mluding area of t@nt openilgs (m'') 

w .. = compartment width (m) 

= compartment length (m) 

~ =compartment height (m) 

A· = area oft@ntilalion opening (m") 

A= 118.54m· 

Ccmpartment Hd Gas Laver TemperatU'e VvUh NatU'al Ventilation 

AT, = 6.85 (Q'I(A(h·,)' ')(A h•)f• 

AT~: = ~: · T,. 

T11 = AT~: + T,. 
J-99

lr!III!IM 

11m~ After 1 ll1on t h, ... T, T, T, 

~ ..... ) ~ C. A0 14 !10 .i "" rF> 

' (+.!)0 - - ~S.(I(I 25.00 (7.(1(1 

1 " (1.22 17UO J."UO ~uo $SU 3 

' "' .1~ ~ .uu~ U~ J.27.7 5 

' "' 0.1$ 20S . .U so~ .J~ 2$$ . .U 452.27 

' "' 0. 11 2 1$.7$ SIU $ 2JH $ 4('0.7 1 

' "' 0.10 227.01 525.01 252.0 1 4SU 2 

" "' 0.07 25U1 $$2.$1 27U1 $$$ ~~ 

" "' 0~ 27U$ sro.u U SH .?'$ 

" 1200 0.05 S~ 2 53U2 $ 1 1.(12 $~ 1.$$ 

" 1500 O.OJ ~U~ SU S~ $2 1.$~ I U4 

" ISOO 0.04 $0~ 2 ~04. 2 $$ 1.(12 27.$$ 

" 2 100 0.04 $ IUS ~IUS $$US .1 ~ 

" 24(1 0 0.0$ $2 1.(1$ US ~.05 ~5 J.SS 

" 2700 0.0$ $27.41 .4 1 $52.41 ~~~ u 

" $000 0.0$ $$$.2 1 U U I $58.21 ?' S 

55 $$00 0.0$ $$$.$$ uus $U.S$ ~s~ $S 

" $~00 0.0$ U$ . .U ~ $~S . .U U5.2S 

1-bt ll:ls l.aye' Terrpe131:u-e 

Nalur3 \krdilalion (MOH Method) 

800 

c:- 700 

t..-600 

~ 500 

1! 400 

GO 300 

~ 200 ~ 100 

0 

0 10 20 30 4) 50 60 

Time lfnin) 
J-100

ESTIMATING SMOKE LAVER HEIGHT 

METHOD OF YAMA.NAANDTAI~AKA 

=- o t1 " )) WH If : "' t•d.t l),<tt l tl)l t .. ) 

0 ·l t~tltUu tnom t 11111 f W) 

t • Uat l!'t I 1)1 UU (lt() 

I • 001Mp)l1ilf ltlt1Jitfl) 

A ~t tfboCMatt~ .. ) 

l • .l Ci0t1 n:utgtt 1 I)Vt. .. O.CI'6'P 

p •lot9)5 b.11CitUit,lf9•) 

p l ght bt P • 3$Jff 

T •IOCg.:ll D-.tlttlpt,_ lt (t) 

0.. Jll,_tnl kta OkUb IOn 

.. - (O')(Q 

WMil A ~um>on•u•fl ) 

W • CCMp.liiJat ttWIJUfl) 

I - CCMp.llllN tl h !JI fl!) 

A • 27.11M 

HoOt G I I UU f Otn 11 \' 011t Ul;lll(ln 

, - J&VT 

Ollt u11111on 110r COn• tint 1.: 

t- 0/116/p 

Smou 011' unr Htl,tlltW tl 11 \11'111 tn tl ~11 n 

: - (";::t.o r.\1\J + <•" ) 

Jlll!lll Caution! The m::~ke l ayw height i s • oonservati~ esti mete and is only 

intended to pro\.~ dean lndiCIIIon W'lere the hot gas layer is located. Calc:ulcted 

smo Ice layer hli ght bll ow the \.9"11. height are not credit able si roe the calculati en 

is net aooountlngfor the smoke edting the '-9-.t.. 

Tllll t ., Com tnnt lJI) ol!t Layer lght Smoh Layu lulght 

Il ) in ) Io- ~ z {II) Z@ 

0 1.11 o.ou 3.0$ 10.00 

O.TS 0. 102 1.8$ \)!) 

0 10, I.U !)!) 

3 0.10 0. 103 I.U !)!) 

4 o.u 0. 111 I.U !)!) 

s UT O. IIS u s !)!) 

10 u .a 0.113 I.U ,.00 

15 o.u 0.12S I.U ,.00 

uo 0. 12' I.U , .00 

--.-.. &,n I.U ~.00 

.. e.sa e.ne us ~.00 

" t.st t .IU us . .. .. ... , t .US us ... " .... t .US us . .. It .... t .IU us ... u-s ... .. us t .UI , ... ... 

CA UTt:Oit Sf,10KE IS EXrTIIIG OUTVI:UT 

UTt:O II: SI.10KE IS EXrTIIIG OUTVEIIT 

UTt:O II: SI.10KE IS EXrTIIIG OUTVEIIT 

UTt:O II: ti.10KE IS EXrTIIIG OUTVEIIT 

UTI:O II: Sf.tOKE IS EXrTIIIG OUTVEIIT 

UTI:O II: Sf.tOKE IS EXrTIIIG OUTVEIIT 

UTI:O II: Sf.tOKE It EXrTIIIG OUT VEIIT 

UTI:>It Sf.tOKE It EXrTIIIG OUTVEIIT 

UTI:>tt Sf.tOKE 1$ EXITIIIG OUTVEIIT 

UTI:>tt St.IOKE 1$ EKITIIIG OUTVEIIT 

UTI:> It: UIC*E IS EXITIItG OUT V!:IIT 

UTI:> II: SUC*f It EXITIItG OUTVfiiT 

UTI:>tt UIC*f It EXffltG OUTVfJIT 

UTI)tt UIC*f It fXmttG OUTWIT 

UTDit UIC*f It f XmttG OUTV!JIT 

UTDtt UIC*f It f l mttG OUTV!JIT 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

~ 

. 

leo 
J-101

Smoke Layer Height 

Natural Ventilation (Method of Yam ana and Tanaka) 

12 

~ 10 0 

~ 8 u. 

E 6 0 

.. 

l:' 4 

"' ·;;; 2 

J: 

0 

0 10 20 30 40 

Time (min) 

The abo\@ calculations are based on principles de\@loped in 1he SFPE Handbook of Fire 

Protection Blgineering, 3"' 6:1ition. 2002. 

50 

Calculations are based on cenain assumptions and ha\@ inherent limitations. The results of such 

calculations mayor maynot ha\@ reasonable predicti\@ capabilities for a given situation, and should 

only be interpreted by an infonned user. 

Plthough each calculation in 1he spreadsheet has been \@riied with the results of hand calculation, 

there is no absolute guarantee ofthe accuracyofthese calcub1ions. 

~yquestions, comments, concerns, and suggestions, or to repon an error(s) in 1he spreadsheet, 

please send an email to nxi@lroQOV. 

60 
J-102

(c) FDT : 09_Plume_Temperature_Calculations.xls s

CHAPTERS. ESTIMATING CENTERLINE TEMPERATURE OF A 

BUOYANT FIRE PLUIVE 

Vet'SiOil 1805.0 

The follcwing calculations estimate the centerline plume temperature in a compartmentfire. 

Per a meters should be specifie::l ONLY IN THE YELLOW INPUT PARAMETER BOXES. 

All subsequent output values are calculated by the spreadsheet and based on values specified in the input 

parameters. This spreadsheet is pro~cted and secure to avoid errors due to a wrong entry in a cell(s). 

The chap~r in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

Heat Release Rate of the Fire (Q) 113100 kW 

Elevation Above the Fire Source (z) 

Area of Combustible Fuei(A:) 

AmbientAir Temperature (T ) 

AMBIENT CONDITIONS 

Specific HeatofAir(C\>) 

Ambient Air Density(P~ 

Acceleration of Gravity(g) 

Convoetiva l-lo.atRolo.a"o l='r.aetion (1¢) 

9D0t 

1200 t 

7700. F 

Calculate 

1 DO kl/l<g·K 

1.18 kghn:. 

9.81 mlsec2 

0.70 

Note: Air densi~ will automatically correct with Ambient Air Temperature (T~ Input 

ESTIMATING PLUME CENTERLINE TEMPERATURE R~ 'li I? •o: =PE.' f~ cbook. OX' .=t~ !Oi?\.r 'f Eig',:'"'<¥1'iiG J "' r~\'f. 2002. Pil{? 2- 0. 

Where J> n•ll~/ = plume centerline temperature ( 0C) 

Oc =convective portion of the heat release raW (kW) 

= ambient air Wmper ature (K) 

g = acceleration of gravity(m/secl 

cto =specific heat of air (kJA< g-K) 

~=ambient air density(k9"m1 

z= distance from the top of the fuel package to the ceiling (m) 

zo= hypotheticalvirtual origin of the fire (m) 

Con'I.Edive Heel Release Rate Calc:ulction 

Oc=1c Q 

Where Oc =convective portion of the heat release raW (kW) 

Q = heat release raW of the fire (kW) 

1c = convective heat release fraction 

Oc= 791.7 kW 

Fire Diameter Calculction 

A:= nDZ/4 

Where 

0 = >( 4 AI") 

0= 

A:= area of combustible fuel (m) 

D =fire diame~r (m) 

1.19 m 

2.H Ill 

1.1 1 m· 

25.00 ~ 
J-103

Hypothetical Virtual Q-igin Calc:ulction 

z.,ol) = -1.02 + 0.083 (0,)>1> 

Where 

z.,ol) = zo= 

zo= virtJJal origin of the fire (m) 

Q =heat release raW offire (kW) 

D =fire diameter (m) 

0.14 

0.17 m 

Centerline Plume T empercture Caculction 

I> (n~Jtrt) · T ~= 9.1 (Tdg CJ>z P~ l 113 0: z>) (z • zof 3 

J> (n~lfrt) · T ~= 448.21 

746.21 K 

473.21 •c llll . ..JI/ Ji 

The above calculations are based on principles developed in the SF PE Handbook of Fire 

Pro~ction Engineering, 3f4 Edition, 2002. 

Calculations are based on certain assumptions and have inherent limitations. The results of such 

calculations may or may not have reasonable predictive capabilities for a givens ituation, and 

should only be interpre~d by an informed user. 

AHhough each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolul»l guarantee ofthe accuracy of these calculations. 

ArPJ questions, comments, concerns, and suggestions, or to report an error(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or mxs3@nrc.gov. 
J-104

(d) FDT : 05.1_Heat_Flux_Calculations_Wind_Free.xls (Point Source) s

CHAPTER 5. ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET 

FUEL AT GROUND LEVEL UNDER WIND.FREE CONDITION 

POINT SOURCE RADIATION MODEL 

Version 1805.0 

The fdlowilg calci.Jationsestim<ne lhe radiative heat1ux from a pool1ireto a targEt fuel. 

The purpose ofthis calci.Jation is to eSiinate lhe 1'3diaticn nnsrrin:ed from a burning fuel anayto a arget 

fuel positicned some distance tom the hat ground level to detennine ifseconmryignitions are likely with no wind. 

Parameters in YELLOW CELLS are Ertered bvthe User. 

Parameters in GREEN CELLS are Autcmaticallv Selected fran the DROP DOWN M ENUforthe Fuel Selected. 

All subsequent oltput \Glues are calculated by1he spreadsheet and based on \Glues speciied in the ilput 

parameters. This spreadsheM is prote~d 3ld secure ro a\Oid errors due to a wrong envy in a oell(s). 

The chapter in the NUREG should be read before an analysis is made. 

INPUT PARAMETERS 

tubss Buning Pate of Fuel (m') OD39 •: 

Effecti\le Heat of Corrbustion of Fuel (AH • .-) 46000 •: 

Enllirical Constant M) 0.71 

Heat Release Pate (Q) 1131.38 •: 

Fuel Aea or Oke A"ea (AM) 1200 

Dstance between Fire and Target (l) 5DO 11 

Radiative Fr.action (1) 030 

O:P:T:10:N:A~L::CA::LC:U:L:A~T:10:N::F:O R~G~1V~E~N~H~EA~T~R~E~LEA~S~E~R~A~T~E ~~~~--_j~~~~~ ~ct"U u sp~c ln &d lu~" trom RJ I T' p~ r.unu and BlterYour HRR h:r~? •:•.:v 

Calttllate 

THERMAL PROPERT1ES OAT A 

BURNING RATE OO.TA FOR FUELS 

1.11 Ill' 

L$Z• 111 

Miss Buning Pate ~at of Combustion :::'~~~nca Seled Fuel T'IJPe Fuel Constant 

m"(kg.tn2-sec) AH~"' (k..LC<g) l4l (m t) 

tlkth3lol 0017 20.000 100 Scroll to desired fuel t}Pe then 

Bhanol 0015 26.800 100 Click en selecti en 

BUI3ne 0078 46.700 2.7 

Benzene 0085 40.100 2.7 

~xane OD74 44.700 19 

~ptane 0.101 44.600 1.1 

X~ene 009 40.800 1.4 

...,. .... OD41 25.800 19 

Doxane 0018 26.200 5.4 

DethyBher 0085 34.200 0.7 

Benzine 0048 44.700 36 

Gasoline ODOO 43,700 l.i 

Kerosine 0039 43.200 35 

Desel 0046 44.400 2.1 

JP-4 0051 43.500 36 

JP-5 OD54 43.000 16 

Transi:lnner Oil, Hyjrocarbon 0039 48.000 0.7 

561 Silicon Transfonner Auid 0005 28.100 100 

Fuel 01, Heavy 0035 39.700 1.7 

Dude 01 00335 42.600 2S 

Lube Oil 0039 48.000 0.7 

D:luglas Fir Plywood 001082 10.900 100 

User ~_p_ecified \klue Enter~lue 8"Jter\klue Erter\klue ~·~w.~: = ~rr«C<JiM ~~ nu-, .,.,., .~r~?-.». 
J-105

E STIMA TIIIG RADIATIVE HE A TFLUX TO A TARGET FUEL 11.' -t"ro:' SFl" ~-.:> « F:~i> «t:.:>n f'Y;j , 3"' &!!len, Z~.l"~ Zi': . 

POINT SOURCE RADIATION MODEL 

q"= 01,/4 liiR:r 

\Aihere q"= incident radiative heat 1ux on the target (kVll.tnl) 

Q = pool fi"e heat release r.Jte (kVll) 

1. = radiati\@ fraction 

R =distance from center ofthe pool fire to edge oflhe target (m) 

Pod Are Diameter calculation 

A u ... = .ll0;:/4 

0= v(4A ~~t:t-) 

Vlhlere 

0= 

A """ = surface area of pool fire (m;;) 

0 =pool fire diamter (m) 

1.19 m 

Heat ~lease Rate CalcUation 

Q = m"AH,..,,(1 • "'~> A 

Vlhlere 

Q= 

Q = pool fi"e heat release r.Jte (kVll) 

m" =mass burning r.m of fuel per unit surtice area (kg.tn1-sec) 

AH .. = effecti'W heat of combustion of i.Jel (kJA<g) 

A = surUce areaofpool h (area invoi'Wd inwporizalion)(m:t) 

kP =empirical constant (m) 

0 =diameter of pool fire (diameltlr imol\@d in wporizalion, circular pool is assumed)(m) 

113138 kW 

Oistarce trcm Certer d the Fire to Edged the Target CalcUation 

R= l+DI2 

mere 

R= 

R =distance from center ofthe pool fire to edge oflhe target (m) 

l =distance between pool hand target (m) 

0 =pool fire diameter (m) 

2.12 m 

Radative !-hat Flux CalcUaticn 

q"= 01, /4 "'R ~ 

The abo'W calculations are based on principles de'Wioped in the SFPE 1-bndbook offire Protection 

&IQineerinQ, 3"' 6:1ition, 2002. 

Calcolalions are based on certain assumptions and ha'W inherent limitJtions. The results of such 

calco IRons may or may not have reason able predicti'W capabilities i:l r a gi'W n situation. and 

should only be interpreted by an infonned user. 

#lthough each calculalion in lhe spreadsheet has been verified with lhe results of hand calcola1ion, 

there is no absolute guarantee oflhe accoracyofthese calculalions. 

#fly questions, comments, concerns, and suggestions, orto report an error(s) in the spreadsheet, 

please send an email to mO@nro.govor mxs3@lrc.gov. 
J-106

(e) FDT : 05.1_Heat_Flux_Calculations_Wind_Free.xls (Solid Flame 2) s

CHAPTER 5. ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET 

FUEL ABO\£ GROUND LEVEL UNDER IMND-FREE CONDITION 

SOLID FLAME RADIATION MODEL 

Version 1805.0 

Th Dt)WIIg cat:U.'IO,_$ thl<l' ~ <t:ll.1tl1~ hat IIU ROlli pOOITU b a tllif.tRH 

Th p1 ~ orut • 1.10H ~ b u 011a' !U l.'ldhOH 1Jaumltt~d 11"0111 a bm • g tul anar b a ug~t 

IU lpoUOHHI $CttH dttUCHICtll 1U Til! abOV~ gDU d I:!J tod~' PII ~ U~ Hd<IIV .;JUtbU all? II ~ I{WU 10 Wild . 

lll'\'lm~ten ln EllOWCEll SU~ En~r~dbj' Ul~ UtH . 

lll'\'llll~ten ln GREEII CEllS ar~ AUbDIIIUCIIII\' $$1$C,dtrom 1h$ DROP 00\Aifl t.1EIIU for th$ f\1$1 h i$CUd . 

. :..I$ II>6$(IIUtOI1Ht tJ<tiH$ <ue ca l h'd ~ $p 1Md, .H t <Ud baad 0 1 V<IIH$ $I=*Crn.d II ~ llplt 

pa 11H~"· n 1$ $p 1Md> • H t 1$ p rotected <Ud $$CI I$ to <WJOI:I $110" \IH b a WDi ge 11t{ II ace II('). 

Th C'<ll)' r• U $ IIUREG $ •0 11:1 be IHd bU01e <U <11<11/$1$ ad! . 

INPUT PARAMETERS 

l.la $$ 6.0119 Ra' OTFH I (II ) 0.039 1 ;.J,bl'•i t ( 

E11'ectm HMt OTCCtllbU1m Off I $ I l:. ,,..~ ,0000 •;J. ,);.J 

EIII tl •t ;J P) 0.7 M 

~atR~ l:aH Rat~ Q) 113 1.36 t! N 

FH l.ol..f~a 01 t;~ Ale a ''-•) 12 .00 II 

Ot;ta•o: b~tN~ u Fll ~ a •d T<119" t (l) ! .00 II 

Vuttal Ot t.'n O? 01Tal9" tf1Ctll GIOU d (H • H, ) 7 .00 II 

O~PT~IO~N~A~l~CA::LC:U:l~A~T~IO:N::F:O R~G~W~E:N~H:EA:T~R~E~LE~AS~E~RA:r~E~~~~~_l~~~~~~ e,l,ot"U "r e1"01t'4 " -,""" frllm F1"1 Ti'l" l.l'n" lln4 a. - r Your II RR l"r' t t!N 

caculae 

THERMAL PROPERTIES DATA 

BURIIIIIG RATE DATA FOR FUELS 

FHI 1.1<16$ s mt•g a~ at Of III • Bllp lltatc o u tl•t Select Fuel Type 

Ill. ;t:gtll ~~" "" t:JJ:gl 1:1.1 •Ill • ' I .. IJ.b• Ctl 

1.11~~'~> 

1-Z II\ 

Z.l3:nlto 

J.t t 0.017 20.000 100 Scroll to d ~ • r~ d fll~ 1 t,• p~ 1l~ n 

eua •o t 0.0 IS 26.800 100 Click on t $I$C1Ion 

Slt.'IH 0.078 ! 5,700 2.7 

~ 0.08:5 ! 0,100 2.7 

na ~ 0.07' U ,700 .. ~rtiH 0 .10 1 ''.600 1. 1 

I:H OD9 ' 0.800 1.1 

:. o: tn~ 0.0!1 25.800 .. Di ~ 0.0 16 26.200 

OI:Q EU I 0.08:5 3' .200 0'·' .7 

'- ~ ODlS U ,700 3.6 

a. llt ~ 0.055 ,3,700 2.1 

l<t 0$ 11 ~ OD» ' 3.200 3.5 

DIH~ I ODlS 'uoo 2. 1 

·-· 

0.05 1 ' 3.500 3.6 

... 0.05' ' 3.000 1.6 

1.'1 Wb Oil ~ I 0 ll HvtiiOC<I b O' OD» ' 0.000 0.7 -6 1 S llt o• TlaU DII ~ I flll:l 0.005 28.100 100 

FH 10 11, ~atiV 0.035 39,700 1.7 

::n o: 0 11 0.0335 ' 2.600 2.8 

lll=* 0 I OD» ' 0.000 0.7 

OOI(ji.U fll PI(Wood 0.0 1082 10,900 100 tn: U E• ll ~ E• ' IV<t!U E• ' ~ tr~~: s.--;:> <K!N" l"~-c.:-n ~ , 3' 6U:o, :OOZ,;>: 

""· 

_, 
J-107

ESTIMATIII G RADIATIVE HEAT FLUX TO A TARGET FUEL P,~ 'l: IUO: :S,:PE "'f<?,i<b.:I C'¢ * Olo;t~\~ Eig llg, ~ E<IID•. ZOCI2,P<?\)"~2i0. 

SOLID FLAME RADIATION MD DEL 

q"= EF· -.-.t 

me .. 

Pool Fire Diameter Calculation 

Au ... = .ll0:.:/4 

0= v(4A ~~<:t-) 

me .. 

D= 

Emissive Power Calculation 

E =58 (1041 Wtt/)U) 

me .. 

E= 

View Factor Calculation 

F·-·:.e· ... = 

F·-·:.ew = 

A= 

1\= 

9= 

S= 

h. = 

h: = 

F·-·:.e .. = 

me .. 

q" = incideM radiative heat tux on the target (kWhn") 

E =emissive power oflhe pool 're flame (kWhn") 

F ._,.J= \iew factor betweentarget and lhe flame 

A u .... = surface area of pool fire (m:t) 

0 = pool fire diam~r (m) 

1.19 m 

E =emissive power oflhe pool 're flame (kWhn") 

0 = diameltlr oflhe pool fire (m) 

56.71 (kWAn' ) 

1(•$)"' ·(h·(S'-1). '}(h-i.S)>n .((S-1)($+1)). '•Ah·i•SQ'< ' ·1). "ian .((A +1XS-1)1(A·1XS.1)). ' 

1(•S)lll .(h'-(S'-1). ')(h" .S)>n .((S-1)($+1)) . . , +Ah""S(Af -1). "ian .((A+1XS-1)1(A• 1XS.1)). ' 

(h ·:l+$:1+1)12$ 

(fl/ +S1 +1)/lS 

(1+S') '2S 

2R/D 

2H, . ..O 

2H,:r..O 

F -4Y' + F. •ltVJ 

F. "Jv =total t@nical \jjew tutor 

R =distance tom cen~rofthe pool fire to edge of the target (m) 

H, =height ofthe pool fire flame (m) 

0 =pool fire diameter(m) 

Dslance fran Center of the Pod Are to Edge of the Target Calculation 

R=l+0/2 

me .. 

R= l+012 = 

Heat Release Rate Calculaticn 

Q = m"AH,..,,(1 • e ~u)A.w... 

me .. 

Q= 

R =distance tom centerofthe pool fire to edge of1hetarget (m) 

l =distance between pool fire and target (m) 

0 =pool fire diameter(m) 

1.815 m 

Q =pool ire heat release rat»l (kW) 

m" =mass burning r.Jte of fuel per unit surUce area (kghn1-sec) 

AH = e~ctive heat ofcombustion offuel (kJA<g) 

A t...., = surface area of pool fire (area involved in -wporization) (m1) 

kP =empirical constant (m) 

0 = diamet»lr of pool fire (diameter involved in -wporization, circular pool is assumed)(m) 

1131.38 kW 
J-108

Pod Fire Aame Heia-.t Calculation 

H= 0235 0:.-0·1D2 0 

\Mere 

H= 

S= 2R.O= 

h·= 2H·/D= 

= 2H•...O = 

A= (h·:.-+S:.-+1)12$ = 

= (h/ +S"+1)12S = 

9= (1+S')QS = 

F· •:tv·= 

F· •:IVJ= 

F· •:t v = F -4v· + F· •:tv.t= 

Radative Heat Flux CalcUation 

EF· •:t 

H = flane height (m) 

Q =heat release r.Jte of1i"e (kVV) 

0 =fire diameter(m) 

2.698 m 

3.047 

3.582 

2(H-H·)ID= 

0.153 

0.081 

0.234 

0.947 

3.793 

1.835 

1.687 

o.o:n '" 

The above calculations are based on principles de'Ueloped in the SFPE 1-bndbook of Fire A"'tection 

BlQineerinQ, ~ 6:1itDn, 2002. 

l:alcolatims are based on certain assunptions and have inherentlimimtions. The resuts of such 

calculations mayer may not ha\le reasonaHe predetive capabilities fora gi'Wn situation, and shouH 

oriybe interp-eted by an ini:lnned user. 

Alhough each calculation in the sp-eadshea has been veri,ed with the resuts of hand calculation, 

there is no absolute guarantee ofthe accoracyofthese calcolatDns. 

Pnyquestions, comments, concerns, and suggestions, or to repon an error(s) in the spreadsheet, 

please serd an email to mO@lroQovormxs3@JroQov. 

f.,_ f .,. F,.>t·"' 

0 -Z) I 0 .):0$ O.HO 0. ~; 

f., 

0~1 
J-109

(f) FDT : 10_Detector_Activation_Time.xls (Sprinkler) s

CHAPTER 10. ESTIMA liNG SPRINKLER RESPONSE TIME 

Version 1805.0 

The following calcolai:Ons eslii'TI3te sprinkler actha:icn time. 

Ponmet~s in YELLOW CELLS are &tered bvthe User. 

Ponmet~s in GREEN CELLS are ALtcmaticallv Selected fran the DROP OOVYN MENUfcrthe Sl:lriri<l~ Seleded. 

All subseq.JentoUiput Wuesare calcol~d bythe sp-eadsheet 3ld based on \Glles speci,ed in1he inp.a 

pa~ameters. This sp-eadsheet is protected and sewre to awid erTa"S due to a wrorg Entry n a cel(s ). 

The chapl»lr in the N UREG shruld be read bebre an analy;is is made. 

INPUT PARAMETERS 

~at Release Rae ofthe Fi~e (Q)(~adyStrte) 

Spri'lkler Response Tine hdex (RT 0 

.A:tM:II:icn Terrp(f3ti.Jre oflhe Spinlder(T- .. ,) 

~ightof Ceilng above Top of Fuel (H) 

Radial Dstanceto1he Oetectcr (fl ""'net@rrmre than 0.707 oc 112V2 of the listed soacioo""' 

.Aroiert Air T errperau-e (T ,.) 

Cont@ctiw ~a: Release Pate Fractim (1 ) 

r.+l= 1.09 

AS. 'AA l'f~r.:t ~~('Of'IF:'II!' S.:,' (';md ~~~rq 1" ;>,..-xc«llfj 

r.t.:~'<:h tV ». ·t;t<:. nY If~-.:r, H:>f?,iKcn!;i P,?. '::11-Z :<I. 

•tet .. 1he: act I RTI h:Udb ed ~ th al hbl "' s eus n •• IRIS<IY<II .. GENERIC SPRINklER I EMPERA lORE RAI lNG ( 1 • .,._.,..,, .... )* 

1131011 t! 

130 

165 ., 

9DO 1 

• 

77DO ., 

0.70 

Calculate I 

T Empel'3tl.lre Oassi0031im Range ofTerrperau~e GenEric T errper.nu-e Select Sprinkler Class 

Ra;nos('l') Ratioos ('f) I Cfdlnar1 ·I 

1).$'9 'C 

ification 

Ordilary 135to 170 165 ~croll to desired spirid erclass 

lrtEmledi<M 176to 225 212 

Hgh 2!{lto 300 275 

8¢1'3 tigh 325to 376 350 

\kryem high 400to 476 460 

Lltra tigh 500to 576 550 

Lltra tigh 6ro 550 

User sbeciM:d \t.!._.e - Enter \t.!._.e ... - .. . ' - ' . ' lt 'tr~rc~ . ,..M .. ~ ... p!:n.JN :t~~"::J~...._ ... \ 6 sa, cr. ,\-:f,~ ~Pi'<:~«J,cn 

,:.~,· :en O(;)Q'. :\i:n~·<'l:ht!Cif:o 19~ P~ 67. 

EsTi'MA'i~~ 

t- ·"""' = (RTL(w,.))Qn (T,.. • T,.)l(r,.. • T ,.,._,,)) 

mere t- ·"""' = spinlder aaiv.alim response time ~ec) 

RT I= spririder ~esponse tine irdex d'n-sec) · :~ 

u,.. = ceilngjet t@bcity(nv'sec) 

T,.. = cQiing ja tEmpel'3tl.lre ("C) 

T ,.= aml)entairtEmpel'3tl.lre ("C) 

T -..,.,., = actM:II:im t»lrrpemure ofspri'lkler(•C) 

Cei lint=~ Jet T empeiOture C<llcU ati en 

T,.. • T,.= 16.9 (O ':IA·f'":: forr.+l = 0.18 

T,... T,.= 5.33 (O • .tt ':l.+t forr.+l > 0.18 

mere T,.. = cQiing jEl tEmpel'3tl.lre ("C) 

T ,.= aml)ent airtEmpel'3tl.lre ("C) 

~ = COI'I'I.@ctit@ poltim oflhe he a release 13te (k\A() 

H = heQht ofcQiing <bot@ tcp of tiel (m) 

r = r.adial distance from the plune centerine to the spririder (m) 

hen Click on selecti en 
J-110

Con~ive Hea Release Rate Calculation 

=~. a 

Where a . = convective portion of the heat release rate (kW) 

a= heat release ra~ of the fire (kVll) 

a.= ~ =convective heat releaser ate fraction 

791.7 kW 

Radial Distarceto CeilinA Heit=~ht Rctio CalcUction 

r/H = 109 r/H > 0.15 

T1 .. . T,. = {538 (acJr)'213}.+t 

T1,. • T,. = 9l.92 

Tt" = 105.92 (•C) 

Ceil inA Jet ~oc:itv Cac:ulaticn 

U.• = 0.93 (a.+t)•,-;t 

4 .. = (0.195 -:~ H · ·'yt 11 

Where U.• =ceiling jetvelocity(nv'sec) 

a= heat release raW of the fire (kVll) 

H =height of ceiling above top of fuel (m) 

for r.+l = 0.15 

for r.+l > 0.15 

r =radial distance from the plume cen~rline to thespririder (m) 

Radial Distarceto CeilinA Heit=~ht Rctio CalcUction 

r/H = 109 r/H > 0.15 

u. .. = (0.195 0"1.<3 Hll1/2)"rll5/6 

u. .. = 1.352 f'Wsec 

sPrinkler kti>aion Time Calc:ulal:ion 

t .-.... m = (RTII(vu. .. )) (In (Tt~• • T,.)"(Tt .. • T""""'"'")) 

II OlE: If \ cha1cu = ·11 UM .. SI)Jinkler does not a ttivate 

'h·"' 

The above calculations are based on principles developed in the NFPA Fire Pro~dion Handbod< 

19" Edition, 2003. Calculations are based on certain assumptions and have inherent limitations. 

The results of such calculations may or may not have reasonable predictive capabilities for a given 

situation, and should only be interpreted by an informed user. 

Although each calculation in the spreadsheet has been verified IA.ith the results of hand calculation, 

there is no absolute guarantee of the accuracy of these calculations. 

Any questions, commen1s, concerns, and suggestions, or to report an error(s) in the spreadsheet. 

please send an email to rod@nrc.gov or rro<:s3@nrc.gov. 
J-111

(g) FDT : 13_Compartment_Flashover_Calculations.xls (Flashover-HRR) s

CHAPTER 13. PREDICTING COMPARTMENTFLASHOVER HEAT RELEASE RATE 

Version 1805.0 

Th fOI.)Wiig ca 'IO,_ $ 1Jil a' 1U Ill" .... Ull hat ~ <16~ 1<1, ~<IUI ~d to Q;llllp<t11111Ut 'IL. O!J~I. 

Pllrlllfl$,ri iO YEllOWCEllS ilr$ Ent~nd bj' UU Uur. 

Pllrlllfl $'rl In G REEII CEllS ilr$ AUtolflll11CIIIIJ' h iHUd fi'OIQ 1U DROP OOVVII f.1E IIU for 1ll$ t.1 ~ter l h iHUd . 

. :. II :<$ ~q iUt I1j lt lt U al~ cat:l 1.1t~d by ~ pl~<ld$ •Htaul b.'IHd o • tJ<tltH p~ ifl?d II ~ " Pit 

p<n<llll$' " · n t ' P'""' ' ' Ht ~ p1W.c'd aut • 1e b atio•:t eno" dH b a w1019 e 11J>{ 11 a o: tl(') . 

Th c•aptH IIIU IIUREG $. 0Hibe teadl=* fOie <U <U<tlf$1$ ~ ma\le. 

UT 

"v" COIII ~\.'U111 UtV"V.:IQ ;, ~ 

COIIIP,'II111 Ut '* l gt• (1.) 

COIII \.'11111 Ut He.;JU (•.) 

w 1tv·v •:n• ;,w-IJ 

W ltHet,.Ut ~ 

20.00 11 

15.00 11 

10.0011 

4.00 II 

6.00 11 1.8)111 

"'lbl lllllg TU:J:.e$$ @) 12.00 1 n 0.))4111 

II' lbllllllg Th Dll<tiCOid i CUJit{ ;J:) 0.0016 •: ........... ~ 

THERMAl PROP ERTlE$ DATA 

l.latHI.'II Th hi a iCOUIICUJit{ Select Material 

•: f;I/VIhl- 1\l i •:Of'l',ft'lt i-1 .O:..IIIllllllll ) 0200 Scroll b d$ 1lr$d m a~ rhl1ll$O Click on t $I$C1Ion 

StH I (OS~ CabO I) 0.054 

CO I~' 0.0016 

W :t; 0.0008 

Gl.'l$$ Pl.'l' 0.00076 

W :t.COICieb U)ct; 0.00073 

Gypnm soar.r 0.00017 

PI('A'OOd 0.00012 

Fl;.; I IU 11.'111H Soard 0.0005 3 

c • IJbo.'lrd 0.000 IS 

ra~d CO I~' 0.00026 

PI. ~ d)O.'IId 0.00016 

c at•m ll• ' Soard 0.00013 

.O:..IIIlllla ll• ' S •x:•; 0.000" 

Gl.'l$$ Fb~l IU lla11H 0.000037 

Eq;.; l dHI (tt{IU~ 0.00003, 

r;.; lrt ll ~ El' rt ~ 

~'IH~~: «te J . J.M: . Prh::~~(ll!$ -;xo.~r.~t'lfflr. !::1..'\r. P:(le'Zi¢. 

PREDICTING FLASH OVER HEAT RELEASE RATE 

METHOD OF McCAFFREY, QUINTIERE, AND HARKLEROAD (MQH) ~-.~~~;$FF$ H:nd:o.». dFI 'l"Pr~'l'bn~~ J o =<ifj:or, !:).\)':_ !'t:\IC 1:\:.. 

Oro• 6 10 !J (•1. .o\, .:..v zy ~) 

\"V hle Oro• hatrH:aa rat~ ~0: 6$ at I11. ~I t:V'V) 

~. tr ~ ~at1JauY: co ~ 1t ;t ihl :t ~ 

I Calcuhte 

A1 • 1\lt.'ll area TU ~ CCtll pal11l UtUC." II9 U 'll'aO: bOI Ul.'lll:$ U CI1<U1 9 ar~a ~ 1101;.; 11194 ~~ ~ 

.t.., • ar~a OTVU1l'111H 01;.; 1119 ~~ ~ 

•v• h.;J ~ ltll'IOH 01;.; 1119 ~~) 

H&atTI'\'I01f:t CO$T1CI$OtO'IICUia11on 

•" • kf;; Auumlng 1llatcompartlfl entha • bun u~d tlorouglliJ' bUOt$ ft athO'.'H . I.$ . t > ~ 

h~e tr ~ hat1JauY:r co~m ~lt ;t ihl ~ 

k • llbf.)f IIUU11U Ill a l COid i CUJit/ i);Wihi-IQ 

;; .,,, 1.)1 hi1 1Hh~H '!) 

1), 1)1)$ kW,tll 4< 

I 
J-112

Aru oTW ntll a11on Op$nlng 0.1eu1a11on 

Av• ;,.w.l) (•.IJ 

.:..v• <H~a OTVUtll'IOH Ct)UI•g Qll) 

~ • vutw•:IQ Qll) 

•v• vut h~U II) 

2.2$ Ill" 

Aru OTCOmpartm $1lt BH IOtlng SUI1\'IU Boundillh t 

At• (N x 0 + 2(• .. x w.) + 2(• .. x IJ - Av 

V'Vh 1e At • bti <H~a TQ~ 00111 pa1111~ •t~ •c•" 119 H 11'<10: bOI Ul.'lll:$ U CIHII•g <H~a ~ •t p~ U· ~ Qll) 

w .. - 00111 pal1l11~ •tw•:IQ Qll) 

METHOD OF BABRAUSKAS 

" - 00111 pa1111 u tl:. gQ Qll) 

• .. - cctll pa1111 ut •e •;~•t Qll) 

<H~a Utii.'IOH Ct)UI•g Qll) 

11$.$4 11'1 :1 

lt~~~~;$FP$ ~~ C(R" i'< ~M:.:r. =rt,Jncc..~rY;J. :i" 61!1Cf\ P~t ?18•. 

0 10• 7&! Avi,,V•.IJ 

hl~ 0 10• hat I~ IMH 1<1, O:U<I t'{ IIL.U· ~ I ;J;V'V) 

<H~a01 Uti1.'10H Ct)UIIg Qll) 

•v• •e •_;~•t U01.'111H Ct)U • g Qll) 

r.un1m um Hut R~ ~~~ ~ RaU tor Fla m over 

METHOD OFT HOMAS lt~~~~:SFP$ ~~ C(R" i'<:~M:.:r. =rt,Jncc..~rQ. :i" &Ill en P~t ?18•. 

0 10• 1 .8 .:O.t + 378 Av zy •·IJ 

Wh I~ 0 10• hat I~ l:aH 1<1, O:U<It IIL.U· ~ I ;J;V'V) 

At • bti <H~a 01 ~ 00111 pa1111~ •t~ •c•" 119 H 11'<10: bOI Ul.'lll:$ U CIHII•g <H~a 01 1.1~ •t p~ Ul ~ ll ~ 

Av• <H~a 01VUtll'10H Ct)U .. g ll ~ 

•v• •e •;~•t utii.'IOH ~ • • g Qll) 

t.11n1m um H&at R~ U ~ Rat~ tor Fill tllOVU 

0 10• 1 .8 .:O.t + 378 Av zy •·IJ 

= 20U.4 1 1tW 1

1ib&i91 

Th abov~ ca•: l l'IO) U <II~ b.'IHd o • pill C., I:$ ~• =*d II ~ S fP E Ha•<lboot 01 fil e 

P D'CU,_ E• iH ~II , 3''

1 EdU,_ , 2002. 

ca•;• h1m ~ a1t batt\1 o• or 1t11• ammpt)H a•\1 •avt 1• H1~ •tllllltl1t)H, n t ltH b 

o1; •c • ca•:• h11H4 mar 01 may •ot <f.! ~ •~a so •., l: p~e U:U ~ c" )abll!»; Dl a g t.ru 

; ltlla11H. a •d ; •o• t l b~ 11' qm'd by a • 1110 111 ~d u~ 1. 

At•o •g • ~a • ca•: ll'IOH "•~ sp1ead6heUas b~u vum.d wt• ~ '~"be on a1d 

ca•: l l'ltb• , U~ 1$ •o <'HOIIte 9 1a1a •tee TQ ~ <ICCI I<IO{ TQ H ca l h1IH$. 

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J-113

Problem 17: Pool Fire Scenario in a Triangular compartment

Problem J-17

Problem Statement

Consider a triangular corner compartment (as shown in the figure) in a boiling water reactor (BWR).

The compartment is 4.6 m (15.0 ft) high with 0.3048 m (12.0 in) thick concrete walls, floor, and

v v ceiling and with a door that is 2.15 m (7.0 ft) wide x 3.0 m (10.0 ft) high (w x h ).

 20'

A fire scenario arises from a spill of lube oil from the high-pressure coolant injection (HPCI) turbine.

Assume that 113.5 liters (30.0 gallons) of lube oil spills in a 1.12 m (12.0 ft ) oil retention dike. The 2 2

lube oil spreads and reaches steady burning almost instantly. Two unprotected safety-related cable

trays are located 3.0 m (10.0 ft) above the HPCI turbine. Determine whether there is a credible fire

hazard to the unprotected safety-related cable trays.

Evaluate the hazard of the fire scenario using the following parameters:

b

(a) pool fire HRR, , flame height, z, and burning duration, t

g

(b) compartment hot gas layer temperature, T , as well as gas layer height z 

Solution

Purpose:

(1) Determine if the given fire scenario could represent a hazard for the safety-related cable

trays.

Solution Approach:

The solution of this problem is very similar to the previous problem, but in this case we do

not have or we are not considering any heat radiation and fire suppression system. First,

we are going to calculate the heat release rate, flame height, and the burning duration of

the pool fire (see Chapter 3) in order to determine the fire source characteristics. Notice

that although the compartment is triangular, we are not going to consider a corner fire. It

is reasonable to assume that the HPCI turbine is at a large distance away from the walls.

Also, we will determine the hot gas layer temperature and the gas layer height (see Chapter 2).
J-114

Once we get all these values, we have to use them to estimate the hazard of the fire

scenario.

Assumptions:

(1) There is instantaneous and complete involvement of the liquid in the pool fire.

(2) The pool fire is burning in the open.

(3) The pool is circular or nearly circular.

(4) The fire is located away from the walls.

(5) The ambient (or initial condition of the air) is at 25 °C (77 °F)

(6) The bottom of the oil retention dike is at ground level.

(7) The distance from the top of the fuel package (oil pool) to the ceiling is 15 ft, the pool

height or oil layer thickness is negligible compared with the height of the ceiling.

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 03_HRR_Flame_Height_Burning_Duration_Calculations.xls

(b) 02.1_Temperature_NV.xls

FDT Input Parameters: s

Enter the following parameters in the spreadsheets (values only):

(a) 03_HRR_Flame_Height_Burning_Duration_Calculations.xls

- Fuel spill volume (V) = 30 gallons

dike - Fuel Spill Area or Dike Area (A ) = 12 ft2

- Select Fuel Type: select Lube Oil from the combo box

Note: When Lube Oil is selected, its properties are automatically selected from the

table and entered in the corresponding input cells.

Results*

Heat Release Rate

kW (Btu/sec)

Burning

Duration

b

 (t ) (min)

Pool Fire Flame Height

Hf m (ft)

1,131 (1,072) 33 min Method of

Heskestad

Method of

Thomas

2.7 (8.9) 3.0 (9.7)

*spreadsheet calculations attached at the end of the problem
J-115

(b) 02.1_Temperature_NV.xls

Equivalent Compartment:

The FDT for hot gas layer temperature and flame height are designed for a s

quadrilateral compartment. Since the compartment is triangular, we have to

calculate an equivalent square compartment in order to use the FDT .

s

 Triangular Compartment Surface Area: 

SA= wall #1 wall #2 wall #3 (1⁄2 x (base) x (width)) + (A + A + A )

SA= (1⁄2 x 20 x 20) + ((20 x 15) + (30 x 15) + (20 x 15)) = 1450 ft2

 Equivalent Rectangular Compartment with Same Height:

SA= Area Floor + Area Ceiling + Area Walls

SA= (L x W) + (L x W) + 2(L x 15) + 2(W x 15)

since equivalent L = W

SA= (L ) + (L ) + 4(L x 15) 2 2

1450 = 2L

2

 + 60L => L = 15.8 ft = W

Input Parameters:

c

- Compartment Width (w ) = 15.8 ft

c

- Compartment Length (l ) = 15.8 ft

c

- Compartment Height (h ) = 15 ft

v

- Vent Width (w ) = 7 ft

v

- Vent Height (h ) = 10 ft

T

- Top of Vent from Floor (V ) = 10 ft

- Interior Lining Thickness (*) = 12 in

- Select Material: select Concrete from the combo box

- Fire Heat Release Rate = 1,131 kW

Note: When Concrete is selected, its thermal properties are automatically

selected from the table and entered in the corresponding input cells.

Results*

Time (min) Hot Gas Layer Temperature

g

 T °C (°F)

Gas Layer Height

z m (ft)

0 25 (77) 4.57 (15)

1 134 (273) 3.05 (10) venting

2 147 (297) 3.05 (10) venting

3 156 (312) 3.05 (10) venting

4 162 (324) 3.05 (10) venting

5 167 (333) 3.05 (10) venting

10 185 (364) 3.05 (10) venting

15 196 (385) 3.05 (10) venting

20 204 (400) 3.05 (10) venting

*spreadsheet calculations attached at the end of the problem
J-116

Conclusions

We can note that the fire power (HRR) and the pool fire flame height values are similar to the

previous problem. The reason for this similarity is because the correlations to determine the HRR

and flame height are based on the type of fuel and the dike area (or dike diameter), and in this

problem we are dealing with a pool fire similar to problem 16. The amount of combustible in the

pool (volume) will determine the duration of the pool fire, that is, the burning time. Thus, we

obtained a different burning time value because we have more fuel volume.

As problem 16, we have a high intensity fire with a flame height that probably will impinge upon the

cable trays. Also, the hot gas layer temperature analysis predicts that the temperature of the gases

will reach the failure temperature for thermoplastic cables (T  425 °F) approximately at 2 minutes

after ignition and the compartment will be full with smoke at this time too. If there is no intervention

of any suppression system during the 33 minutes of flame exposure, there is no doubt that there

is a credible hazard for the safety related cables.
J-117

Spreadsheets Calculations

(a) FDT : 03_HRR_Flame_Height_Burning_Duration_Calculations.xls s

CHAPTER 3. ESTIMATING BURNING CHARACTERISTICS OF LIQUID POOL FIRE, 

HEAT RELEASE RATE, BURNING DURATION, AND FLAME HEIGHT 

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J-118

ESTIMATING POOL FIRE HEAT RELEASE RATE 

P,Ui 1~ •o: : S ,=p E .'·f~.;cbc..W. ot ,={,* P:o lo;t ~ e.g t. tr,g , :j"' 6:1 lb •, 2002, P~~ J-25. 

Q = m"lLH ~.,, (1 • e ""0

) At...., 

Where Q =pool fire heat release rate (kW) 

nt' =mass buminQ raW of fuel per unit surface area (kWm2-sec) 

lLH ~.,, = effective heat of combustion of fuel (kJA<g) 

A= ~o. .. =surface area of pool fire (area involved in vaporization) (m2

) 

kP =empirical constant (m ·) 

D =diameter of pool1ire (diameter involved in vaporization, circular pool is assumed) (m) 

Pod Fire OiamSer Calc:ulal:ion 

~~o.. = 71()"/4 

Where At...., = surface area of pool fire (m2

) 

D =pool fire diamtl>!r (m) 

D = v( 4A. ~o../79 

D = 1.191 m 

ESTIMA liNG POOL FIRE BURNING DURATION 

(U:IH:I> Wlli tel.1t11W . tU 'll.'l>. pollt, II ~ 1J<m1HIIUOII, 1~ l'lle 

t•~a bd 

t:.=4V/7C/ v 

Where t:. =burning duration of pool fire (sec) 

V=volume of liquid(m' ) 

D =pool diameter (m) 

v = reQression rate (nv'sec) 

CalcUction for Ret=~ression Rate 

v = rrt'lp 

Where v = reQression rate (nv'sec) 

rrt'- mass burninQ rate of fuel (lq:r'm2-sec) 

P =liquid fuel densitv(lq:r'm:t) 

v = 0.000l51 nv'sec 

BurninA Duration CalcUction 

=4V.mD ' v 

ESTIMA liNG POOL FIRE FLAME HEIGHT 

lvETHOD OF HESKESTAD 

P,e'IHUO: : =PE.'·f~.i<b~;.W. oT.:i.* P:Ulo;t~'\~ S:g ll l'iig .':!" E<IIIIU, 19i't5, Pag: 2-10. 

,. Ho=D.235 Q · 1.02 D 

Where H, = pool fire flame height (m) 

Q =pool fire heat release rate (kW) 

D =pool fire diameter (m) 

Pod Fire Flame HeiQ-4 Calculation 

H1 = 0.235 r:fo • 1.02 D 
J-119

METHOD OF THOMAS 

Pi~ 't<NU: s;::p=~-..:J..('( «fbn 'n;J. "" &IIICf\ I~ P~ ~ZOO. 

H, • poolm Thill ~ h.;JU (II) 

m• • Ill aa IU Qllg "'' OT1U lp? I I I lH ltiO: <ma ;J glhl ¢) 

p,.• <llllb'"ltallm ult'{ ;J;g.hl) 

0 • p001111e II.'IIIH~ I II) 

g - grwlti1JHa cc~l? rau,. ~~ ~ 

Pool Fi r~ Flam$ Helgllt0llcula11on 

H,• 1.2 o Qll"l p,.v@ D))'"' 

!H,= 2.35 m 

Flame, HtHoht Calcul:~t.on · Summanrof Results 

C iliCUh'IUOO f.1 &1hOd 

r.1ETHOD OF HESKESTAD 

r.1 ETHOD OF THOMAS 

11 '441'4' 

ESTIMATING POOL FIRE RESULTS FOR RAND OM SIZE SPILLS USING INPUT PARAMETERS 

~:. (m 1

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J-120

(b) FDT : 02.1_Temperature_NV.xls s

CHAPTER 2. PREDICTIIIG HOT GAS LAYER TEMPERA lURE AIID SMOKE 

LAVER HEIGHT Ill A ROOM FIRE WITH IIA lURAL VEIITILATIOII 

COMPARTMEIITWITH THERMALLY THICK/THIII BOUIIDARIES 

Version 19l5D 

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THERMAL PROPERTIES OFCOf.1PARTf.1EIIT Elt::LOS IIIG SURFACES FOR 

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EXPERIMENTAL THERMAL PROPERTIES FOR COMMON INTERIOR LINING MATERIALS 

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~ll !ltlo'm 

~ll !ltlo*m 

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lo' " :lolm 

:lll~m 

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Lilo:r•• ·I 

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Oick tl~ ~cu n 
J-121

FIRE SPECIFICATIONS 

Fire Heat Release Rate (Q) 1131.00 •:•.:v 

Calt ulate I 

METHOD OF McCAFFREY, QUIIITIERE, AIID HARKLEROAD (MQH) ~'t•~rr:~:SFP H~-..'\ C(F ~Pi'<:~~a:.m ~nc-HN;J i" &Ui ,~. P~~ 17$ . 

Where AT11 = T 11 · T,.= upper layer gastempemure rise abot@ ambient (K) 

Q = heat release r.Jte oflhe fire (kVll) 

A · = area oft@ntilalion opening (m') 

h·: =height of ventilation opening (m) 

~ = convective heat transi!r coefficient (kW.tn :t -K) 

A =total area oflhe compartment enclosing surface boundaries e:mluding area of t@nt openilgs (m:t) 

Area d Ventilation Opening calculaticn "'= (w") (h.,) 

mere A · = area oft@ntilalion opening (m") 

Wv= vent widlh (m) 

h·: = t@nt height (m) 

A · = 6.5om" 

Thermal Penetration Time Calculation 

t p = (pc.-11<) (6D.i 

Where t 11 =thennal penemion time (sec) 

p = interior construction d ensitv (kAhn 1 c11 = in~rior construction heat capacity(k.IA<g-K) 

k =interior constructionthennal conductiWy(kWhn·K) 

6 = int:eriorconSII'\Iction thickness (m) 

26128.98 sec 

Heat Tranifer Coefficient CalcUaticn 

~ = v(kpc.t) fort< ~ or (k/6) fort> t p 

mere = heat11'3nsfercoefficient(kWhn:t·K) 

kpc = int:erDrconSII'\Iction 1hennal inertia (kWhn :t.K):t -sec 

(a thermal property of material responsible forthe me oftempemure rise) 

t =time after ignition (sec) 

See table below for results 

Area d Compartmert ErclosinA Surface Bcun::laries 

A= [2(w )+2(h xw )+2(h xlc)]·A· 

mere A =total area oflhe compartment enclosing surface boundaries e:mluding area of t@nt openilgs (m'') 

w .. = compartment width (m) 

= compartment length (m) 

~ =compartment height (m) 

A · = area oft@ntilalion opening (m") 

A= 127.ssm· 

Ccmpartment Hd Gas Laver TemperatU'e VvUh NatU'al Ventilation 

AT, = 6.85 (Q'I(A(h·,)' ')(A h•)f• 

AT~: = ~: · T,. 

T11 = AT~: + T,. 
J-122

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" \f~!JIJ IU' ~ l! l<.l£ ~ IU. 14 1.'$! .14 ~~~.~~~ 

" $~!)!) (U)$ 2 15.24 51$.24 24(1.24 JUU 

1-bt ll:ls l.aye' Terrperatu-e 

Naura \kntil31ion (MOH Method) 

500 

E40o 

~ 300 ! 200 

:!!. 100 

t 

0 

0 10 20 30 4) 50 60 

Time lfnin) 
J-123

ESTIMATING SMOKE LAVER HEIGHT 

METHOD OF VAMA.NAANDTAI~ AKA 

=- ~o 

11\!Hif 

\I'M) + (Irl )) 

: - u nd.t L\,'tl l tl)l t f•) 

0 •lt<ltltlt<IU In Oftlt 111! f.W} 

1 • UU 11'1 I !)1 l tll (ltC) 

I • (JI)IMJ))ItU 1tlt1Ji t .. ) 

A • OOMI)~fl tnKIUIU .. ) 

I. • OIOOU1illltg ttl 1)¥1. • O.CJ:&fp 

, •lot9)1 la,11CitUI\If!J'-) 

, l g l't• .,. , • )01' 

T - IOC9<)1 D..t l ._ptllel l! (.t) 

O.Cll,..tniiiN OkUIIIOn 

A - tw)(l.) 

~ A ~fltfDOfM.Jfl) 

W • W.p.l .... ltWI:Ji fl) 

I - OCMp.l .... IU "'JI .. ) A - U . J) M 

w.ot G • ' un r Otn '' \' O le UI:.IIOn , - ..,. 0 11C UIII110n 110rCOn1 t.lnl ._ 

1.- Otn6/t 

smou G:u u nr HtiStllfW tl 11 ~ \1n 1 Vtn11:.11on 

: - 6::1.0 f.\1\)+ fiJI ' 

all Caution! The m::~ke l ayw height Is • oonservati~ esti mote and is only 

intended to pro-Jde., lndiCIIIon W"lerethe: hot gas layer is located. Calc:ulcted 

smo Ice I ayer hli ght bll ow the \.9'll height are not credit able si roe the calculati en 

is net aooountlngfor the srnoke exiting the 'M"It. 

n••~,•, "' COnatmtll! ) Smol!t Layer t Smol!t Laytrh$lght 

Ill ' in ) .. w .... ,. Z {II) zn 

0 1.11 o.ou 4.$1 15.00 

--.-..- Oou us 10.00 

2 o.u o.no us 10.00 

9 0.12 0.0'2 us 10.1)(1 

4 0.11 O.OU us 10.00 

5 0.10 0.03$ us 10.00 

0.77 O.OU us 10.00 

101 us 10.00 

20 0.74 O.IOS us 10.00 

" 0.1) O. IU us 10.00 

" 0.12 0. 105 us 10.00 

" 011 0.107 us 10.00 

.. tJI t .toT us "·" "' --.-..-. us "-" .. tJt .... , us , .... .. t .U t .llt us .. t .U t .llt ... , "·" "·" 

CA UTt:Oit SMOKE IS EXrTIIIG OUTVI!IIT 

UTt:OU: Sf,10KE IS EXrTIIIG OUTVI!:IIT 

UTI:OU: Sf.tOKE IS EXrTIUG OUTVEUT 

UTI:OU: Sf.tOKE IS EXrTIUG OUTVEUT 

UTt:.U: Sf.tOKE IS EXrTIUG OUTVEUT 

UTI:OU: Sf.tOKE IS EXrTIUG OUTVEUT 

UTI:) 11: S f.tOK E IS E X rTIUG OUT VEUT 

UTI:>U: Sf.tOKE IS EXrTIUG OUTVEUT 

UTI:>U: Sf.tOKE IS EXrTIUG OUTVEUT 

UTI:>U: UAOKE IS EXITIUG OUTVEUT 

UTI:> II: CI.IOKE IS EXITIUG OUTVEUT 

UTOit CI.IOKE IS EXITIItG OUT VEUT 

UTI:>H: SUOKE It EXITIItG OUTVBIT 

UTJ:>It UIC*E It EXrrtUG OUTVfJIT 

UTI) It UIC* E It EX ITitG OUT VfJIT 

UTI) It SIIOt<E It El mttG OUTWIT 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

CA 

leA 

leA 

leA 

b 

b 

. 

"' 
J-124

Smoke Layer Height 

Natural Ventilation (Method of Yam ana and Tanaka) 

16 

e 14 

0 12 ~ 

u. 10 

E 8 0 

.. 6 

l:' 4 "' ·;;; 2 J: 

0 

0 10 20 30 40 

Time (min) 

The abo\@ calculations are based on principles de\@loped in 1he SFPE Handbook of Fire 

Protection Blgineering, 3"' 6:1ition. 2002. 

50 

Calculations are based on cenain assumptions and ha\@ inherent limitations. The results of such 

calculations mayor maynot ha\@ reasonable predicti\@ capabilities for a given situation, and should 

only be interpreted by an infonned user. 

Plthough each calculation in 1he spreadsheet has been \@riied with the results of hand calculation, 

there is no absolute guarantee ofthe accuracyofthese calcub1ions. 

~yquestions, comments, concerns, and suggestions, or to repon an error(s) in 1he spreadsheet, 

please send an email to nxi@lroQOV. 

60 
J-125

Problem J-18

Problem Statement

The operators of Bywater NPP are planning their summer company picnic. A fire scenario arises

from a pile of instant-lighting charcoal briquets. Ten 3.62-kg (8.0-lb) bags of these briquets have

been stored on the floor of a corridor in the NPP. Assume that a strong ignition source is present

and fignites the charcoal briquets. Compute the heat release rate, , flame height, H , and

bu brning duration, t , of pile of charcoal briquets, assuming that the area of the charcoal pile is

0.28 m (3 ft ). 2 2

Additional Information

Charcoal briquets are a combustible material and become more combustible when soaked with

lighter fluid (an accelerant) during the manufacturing process (Ref. 1). The lighter fluid is usually

kerosene or a petroleum distillate (Refs. 2 and 3). No direct burning rate data are available for

instant-lighting charcoal briquets. A breakdown of the combustion data for plain charcoal and

kerosine (Ref. 4) is provided below. Average values can be used as a composition when specific

burning rate data are not available. The density of charcoal is approximately 400 kg/m .

3

Combustion Properties of Charcoal and Kerosine

Combustible Material Heat of Combustion

Hc (kJ/kg)

Mass Loss Rate

 (kg/m -sec) 2

Charcoal 31,400 0.01082*

Kerosine 43,300 0.039

Average 37,350 0.02491

* Mass loss rate of charcoal is not available in the literature, mass loss rate of

plain plywood can be used, since charcoal is a derivative of wood.

References

1. Roblee, C.L., “Hazards of Charcoal Briquets,” Fire and Arson Investigator, Volume 33,

No. 3, March 1993.

2. Lincoln, S., “Case in Review: Charcoal Lighter Fluid Used as an Arson Accelerant,”

Fire and Arson Investigator, Volume 41, No. 1, September 1991.

3. Wiltshire, L.L., and R.S. Alger, “Carbon Monoxide Production in Charcoal Briquete

Fires,” NOLTR 71-104, Project MAT-03L-00/ZRO11-01-01, Naval Ordnance

Laboratory, Silver Spring, Maryland, July 7, 1971.

4. SFPE Handbook of Fire Protection Engineering, 2 Edition, 1995. nd
J-126

Solution

Purpose:

f b (1) Determine the heat release rate, flame height, H , and burning duration, t , of the pile

of charcoal briquets for the given fire scenario.

Solution Approach:

To calculate the HRR and flame height, we are going to use the pool fire approach. These

calculations are just fuel type and area dependent; therefore, we are going to model the

area of the charcoal pile as the area of a dike and use the average values of heat of

combustion, mass loss rate and density (values are given in the problem statement). The

burning duration of the pile can be calculated with the learned concepts in Chapter 8 of

NUREG.

Assumptions:

(1) There is instantaneous and complete involvement of the charcoal pile.

(2) The charcoal pile is burning in the open.

(3) The charcoal pile area is circular or nearly circular.

(4) The fire is located away from the walls.

(5) The ambient (or initial condition of the air) is at 25 °C (77 °F)

(6) Combustion is incomplete and takes place entirely within the confines of the

compartment.

Spreadsheet (FDT ) Solution Procedure: s

Use the following FDT :

s

(a) 03_HRR_Flame_Height_Burning_Duration_Calculations.xls

(b) 08_Burning_Duration_Solid.xls 

FDT Input Parameters: s

Enter the following parameters in the spreadsheets (values only):

(a) 03_HRR_Flame_Height_Burning_Duration_Calculations.xls

- Fuel spill volume (V) = 0 gallons

dike - Fuel Spill Area or Dike Area (A ) = 3 ft2

- Mass Burning Rate of Fuel = 0.02491 kg/m -sec 2

c,eff - Effective Heat of Combustion of Fuel ()H ) = 37,350 kJ/kg

- Fuel Density (D) = 400 kg/m3

- Empirical constant = 100 (since unknown)

Note: For this calculation, use any value of spill volume because the burning time

based on the pool fire calculation is not applicable. We are just going to accept the

HRR and flame height values as reasonable estimates. Mass burning rate, heat of

combustion, and density values are from the given properties in the problem

statement. Select User-Specified Value and enter the values in the proper areas.
J-127

Results*

Heat Release Rate

kW (Btu/sec)

Pool Fire Flame Height

Hf m (ft)

Method of

Heskestad

Method of

Thomas

259 (246) 1.56 (5.13) 1.38 (4.54)

*spreadsheet calculations attached at the end of the problem

(b) 08_Burning_Duration_Solid.xls

HRR per Unit Floor Area:

The HRR per unit of area is defined as . Therefore, from the given

properties in the problem statement we have:

= 37,350 kJ/kg (0.02491 kg/m -sec) = 930 kW/m 2 2

Input Parameters:

solid - Mass of Solid Fuel (m ) = 80 lb

fuel - Exposed Fuel Surface Area (A )= 3 ft2

- HRR per Unit Floor Area = 930 kW/m2

c,eff - Effective Heat of Combustion of Fuel ()H ) = 37,350 kJ/kg

Note: Select User-Specified Value and enter the inputs.

Results*

Material Burning Duration

solid t

(min.)

Charcoal briquets 87

*spreadsheet calculations attached at the end of the problem
J-128

Spreadsheet Calculations

(a) FDT : 03_HRR_Flame_Height_Burning_Duration_Calculations.xls s

CHAPTER 3. ESTIMATING BURNING CHARACTERISTICS OF LIQUID POOL FIRE, 

HEAT RELEASE RATE, BURNING DURATION, AND FLAME HEIGHT 

Wn lon IM+$.0 11.- 1: O' rt,I O.I~ nl U IM~ 1.-1.-~ ~INoa ~ , lo.ti11V U~I Cf\ ~'ol1~0\t l'd.,\l1:f <J~I4J>od ·~· 

f'I ll ~- n VBlO'NCB le u~ 81-"4 I> ~ II . 

P~ 10 ~- n GRESI CB le ~ Alltlm11 ."t; e"~ -4 Tllm '" OFOP OO'N III.IEIIII1\lrU" Flld e"~ -4. 

ft ~ .. ~<1\IIOI CO. .. \IIt,t~~~l ~~ 1~4 t.:o· 1 .. :r>r~~lil~l ~ 1>~ t,·~~ ll> 'k 1n 1 .. l't>\11 

~~~0\t 1!11. 1111 f> ~~HI'H Ill f>I 4 'ol ltO.ft ~.1C l CU ~ ~ V.ICffl ~nly h ~ 00 . 

11 .. clll>~ h h IIIII ll..,. ll> ll>#:r~ ~\~~fllll ~k. 

IN Pili PABAMfifBS 

htl Cltii CI~IO\t M 

htl Cltll f.ft~ ct Ob frt~ O'<, ..) 

l.bll 61, ..... ),1 ~ 01'htl(lol") 

Eftct ~ ~~~~• o~ o. cn01' hd (til ..) 

htl ~n:llj ) 

BowtleaCcnlb1{t:l') 

flolt.knl ;..t TUolr>~•~ (r) 

Gr~.l bi CNII Ao:dff~l lll .8 "•••' 

,.,.,l>kni.Al Otn:t.- (p ) 1.18"""'' 

I Ollcula' I II ~: f.) •kn:lljW I41 ~e:ilyo:rr~ 'A .Aiiitltl'll ftl 'nloll>ff~ft (rJ iV.Ii 

Til Ef:t.IAl PftO PERTIEe DATA 

611RIIIIIG RAT E OAT A FORU l iiiOIIYOftOCAR&j ll FUEl" ' 

"" 1.1 1 m1rt,~ lt.ok ~~~~1 01' lit~ cn o~n lll lol"(l:lllol' •lt C) II .. {t:J,14 ) {t:f'h\ ') 

'·~·~ 0.0.7 !"'"" , to; 

a~..:t O.OIS ~.tro ••• klb't o.as .S,i'OO 

k=~ 0 .<0; ' ' ll~b't ~ o.a• 

0 . 0 1 

"'

Hi<O 

H ·,i'OO "' ~ >\.IN't Of» .01<0 ~~ A: l:, .. o.ou .S.tOO •• o 

'"""' 0.0.8 

!:: oo:< Oki)' Ehtl 0 .<0; .. k""' o.oos H ,i'OO .. cfoe ows .),i'OO 

l

Ok

'tiO

~1 

!II .. O.a>9 

o.oos """' H , £0 ~ 0$ 

JP·• 0.0<0 .) ~ '"' "" O.a<• """ 00 

11~ 1:rro~tr OII, II)'<IIOQ'bcn O.a>9 $ 1 ct o: ~1:oo~u rur O.<OS ~ .'.. "'hd 0 1, HNo'.J' oms 39,i'OO &70 

Cl\ok OII omn .,,.., ~~. .. ~ 0 1 O.a>9 .. .., ~ 

11 1N Qt 'k4 'V:il~ B*I V4 U 8\• ~~ 'B'k "' 4~~ 

~•u•«U ~ ........ ...-.-4 ... h _,.,.,,. _,_ '-'~<-·"'"~--~,/<.. 

Bo1tllt:~ Ccn1 b\1 t: ....... e~~~~• "' ~' 1> ~ I I ·! 

"" ~l'llll t~4 h4 ~• r>~ 

"" on u~n 7 

7 

.. 

... 

... 

.. 

0'·' .7 ,. 

2.1 

'2·.1 ' 

,. 

.. 

0 .7 

"

1.7 " ,. 

0 .7 

B* ~~ 
J-129

ESTIMATING POOL FIRE HEAT RELEASE RATE Pi~'t<NU: s;::p=~-..:J..('( ~P «fbn~'n;J, ~ &lll cn P:(Ir :.6. 

a ·m·t:. ~.,, "" .:..

'l>Hm o • poolm hatiH:aH 1at~ ;J:ItV) 

m• • Ill aa IU Qllg "'' OT1U ~ I I I l H ltl~ <ma ;J glhl ¢) 

!:.H...,,• ll' ~ hat01COIIIIU$0H 01 r. ~ I ;J;J,I;g) 

.t...• .:.,».. • H ltiO: aJ~a poO I111 ~ tea II VOIJ~d " vapOIIZat.,.) ~~ ) 

p • ~IIIP IIta co"t.'llt \Ill ) 

0 • di.'II1HtH 01pOOITII! II.'Wil ~~l ll tJO lll vapOIIZaOH CIICI 1.11p001 ~ a6H ill~ {!; II) 

Pool Fi r~ Ct am~ tHOl ul 11 n 

.:.- - ,o·" .:.,,....,. H mo: a~~ a Tpoo ln~ ~~ ) 

o- oo1111 ~ <11.'1111' 1 QR) 

m 

~il t R~ U t~ Rat~ OliCUia11on 

Q • Ill • !:.H...,, (H '*) .:.,11<1 

(UI\tH V.l hrd~lt:~ly l't.lll ta:ll J>dnl ll~ t:n 1:tl11U l~<l\&~ 

t:~ ~~~rt.l ~"J*~ hNI:O) 

t> = 253.31 kW 2J5.73 Btuluc 11 '44U§J 

ESTIMATING POOL FIRE BURNING 0 URATION 

~·tf~ru: s;::p=~-..:J..('( ~PU« bn~'n;i. f" &III f\ I! P- ~IW . 

\,• w / !1 02V 

'iV hle t, • bUI•g dH'IOH OOITII ~ ) 

VO IUII ~ OTit iHI \Ill ~ 0 • pOOl <ll'IIIH ~ I ~~) 

.,. ~9 ~H.,_ 1<1, ~~~~ e) 

CalcUh'IUon for R~ gr~ u lo n RaU 

., - 1(1"/ p 

li>J HI~ .,. ~9 ~H.,_ 1<1, ~~~~ e) 

lll" •hl<l$$ bUUIQ 1<1 , UHI ;J <aihl ¢) 

p • II:JHI l <I! "It{ it gihl ~ ., • (1.1)(+(+(+~ 2 IIIMC 

eum1n~ C4.1rauon Ollc u1a11o n t:.• Wt' O'\• 
J-130

ESTIMATING POOL FIRE FLAME HEIGHT 

METHOD OF HESKESTAD 

"-', ... ._.. SN'I:I(""'dllt><IAcU,I'O~'-M"t>'liJ""' .. 'II t''biOOill ' !V5 l')o~J>lt- 0 

H,• 0.23SO'"'- If£. 0 

V\1 ~ te H. • pool life 'll.'IIM ~ tJ•t {II) 

O • poo1111 e hattel:aa r~ ;J;V\1) 

0 • pOOITU dl'WII~~I ~II) 

Pool Fi r~ Flam~ ~Hil OI cu aU n 

H,• 023SQ'-- 1Jr!. D 

II•·= "'' m 

METHOD OF THOMAS 

s.u n 

""' ... '"'" ';1-~'I:H..,<I'IIt><>tclf,IOI'-ft:>fll;.olJIIO .. 'II :t''blOOitl 10~ l'>ol":loll/).1 

H,•J2 D Qll 'l p,.v g o.»~' 

a~ te H.· poo1111e 'll.'llll~ ~ t~•t {II) 

It( •Ill <IS$ bUUUI I~ OTIUipe I UltH In:.: <liM ;j;<JIII ~e¢) 

p,.• <rllb~ •ta lldU$l•f t;g,tll ) 

o • poolm dll'•HtH QR) g • gl<ri lti1J)Ial<t:o: ~ o1m {IIA:eC') 

Pool Fi r~ am~ ~Hil OI cu aU n 

H·· ' 2 o ~~~ .- v g D))"L 

II•·= 1." m 

Fltmt Htlant Clltulttlon - lum mtrr of Rt aulte 

'""" 

'""" 

ESTIMATING POOL FIRE RESULTS FOR RANDOM SIZE SPILLS USING INPUT PARAMETERS 

AU3 (Tt') AA:t (m ' ) Dam~ter llfl Q~'M t.,(tH ) ftt){ tld 

I (1.1)3 e.u 3U4 0.00 .... ' 0.13 0.43 172.37 0.00 "'' ' (1.23 ~0 253.31 0.00 $.1$ 

J 0.$7 ~3 UUJ 0.00 H3 

' Uli o:rr 4$2. IS 0.00 us 

' o.ss O.SJ SIU2 0.(+1) us 

' o.ss 0.31 sos.os 0.(+1) us 

• O.fJ 0.37 SH-13 0.(+1) 7.23 

' o.u 1.(+$ 777.32 0.(+1) uo 

" 0.3$ 1.03 SSUS 0.(+1) 7.$3 

II 1.02 1.14 3SO.SO 0.(+1) us 

" 1.11 1.13 10$7.2$ 0.(+1) S.Jl 

" 1.21 UJ 112U7 0.(+1) us 

14 uo 1.23 12 10.10 0.(+1) us 

" 1.$3 U$ IUUJ 0.(+1) 3.10 

" us UJ 172$.72 0.(+1) IO.OS 

" 2.$2 1.72 2 1S0.30 0.(+1) IUS 

" us U$ J$21.$0 0.(+1) 1$.$1 

7S U7 2.3$ USU3 0.(+1) IS.U 

"' 3.23 UJ SU$.$3 0.(+1) 17 .JS 

H, 1tHlhcma t 

$.1(1 

3.35 

UJ 

5.02 

U$ 

$.($ 

uo 

U3 

us 

uo 

7. IJ 

us 

r.ss 

u s us 

$.($ 

3.43 

IUS 

1$.30 

15.$7 
J-131

Caution: The purpose of this random spill size chart is to aid the user in evaluating the 

hazard of randomsized spills. Please note that the calculation doe nott~e into account 

the,.;; cc~ ~v orv·olatil ~ of the liquid, or the absorptivity of the surface. The results 

~'"!rat~forsnlallvo•lurne spills over large areas should be used with extreme caution. 

The abo\le calcolatOns are based en principles de'Ueloped in the SFPE 1-bndbookof Fi~e 

P!Wlction Blgileering, 2rld Ei::lition, 1g95. 

C31c1Jations are based on certan assumj:tionsand have inha-eM linitalions. The results 

of such calcolaticns mayormaynot ha\le reasonable prediaive capabilities i:lr a gi\len 

stu31ion. ard should onlybe interpreted by3l ini:lnned user. 

Mlough each calcol31ion n the spreadsheet has been 'Ueriied with the results of hard 

c-'culalion,there is no absolute guarantee ofthe accoracyoflhese calci.Jations. 

#fly questions, comments, coroems, and suggesticns, «" 10 ~eport an error(s)inthe 

sp-eadsheets, p~ase send an email to m0@"roQovorllli.::S3@lroQOV. 
J-132

(b) FDT : 08_Burning_Duration_Solid.xls s

CHAPTER 8. ESDMATIIIG BURIIIIIG DURADOII OF SOUD COIYIIUSDBLES 

Versicn 1805.0 

~ Dt:tA'Itg cabU.11))1$ r.~,t '"; a a <WICdllatln OTIU bm119 <1t l.'ltln OT$Oit iCCtllbUU>h :.a>~d 11lH 

bmllg r~ wt• agiJu Hit.:.: a~: a. l>.'lrnm~ten In YEllOWCELLS 11r~ Enter~d b'.' 1l$ UtU. 

P:lrnlfl$ter, ln GREEIICEllS ~~~ AUbmat call\' S$I$CUd rom 1l$ DROP COWl f,tf11Ufor 1l$ f.1 3tel1111 S&I$CUd 

:..l nb~ l• •t l1 1t au; ~ ca •h~db ~ ' P" <t:l$h~ta d l>~d au' pe d 111u • p•t 

p.1r<r1H'"· n~ pre<t: h~tt pro-.~d <nd ~ate b<rJo ero~ <IH ba wro1ge 11r>{ l1 a~ If) . n e c ... ,,,. 1u ttUR ~ ' 'o••:lbe tea:ll:.e'lm a1 <uat,~ t ~ ma:l!. 

Ill PUT P ARAIYI:TERS 

COt.1PARn.1fiiT IIIFCftf,tA 110 11 

l.taa OTSOI:I fl el II ·~ .) 

E)J>Oad Fbor.:..l!a i!-Ugli x V\

1

t llll) 01 Fte ' ' ' .....,) 

Heatl'l:t:<.oe ~~ ~IUilf OOI.O:..tea (Q") 

Elf!CU.I? ""atoTCCtlllm1m ~ ..) 

<:;~•fW..~It-~~· .. ,.....-,,.·~~ 1')1!--~ -dJ)i\~.! .V-~1:U. .ol't1 

1(,1,_,...,<1~ ....... ~.,., ...... ,_...,r;.....,,._ 00-<l C....llrll'l<*-i'!R • 

<:.-.::~ ........ 1~~ 

ii~"""lof ,',I f,l. 'Ho.-/..,. .... _,~ ... /lt.e f,b'1:""'A'ii ... l/'!--l~t<f<IA. tl.~, .... - .. ...t 

(;,~_.. bf(Q'A b.loo·-/.o1Piod:l_.,.,. ·~.-._ 
J-133

BURNING DURATION OF SOLID COMBUSTIBLES P,~'li 1? •o: -clliJ,UJ, . A .• "'f, :S.'Ct ii CMs..'i}~ itir ,: {,* Sil~;y. · a:vn. Pil(? 3~. 

The burning duration of a solid fuel can be calcula~d if the total energy contained in the fuel and HRR are known. 

The burning duration is given by: 

Q = E /t,ct<l 

or 

t 1ct<1= (E)/(Q" ~u~ 

Where bc1<1 = burning duration of solid combustible (sec) 

E = mh~~tlLH = total energy contained in the fuel (kJ) 

Q =heat releare rate of fire (kW) 

Q" = heat release raW per unit floor area of fuel (kWhn') 

Ah~~t =exposed floor area (length x width) of fuel(m") 

t.~= (mhtllLHc) I (Q" Ahl!t) 

Where mh~~t =mass of solid fuel (kg) 

lLHc =fuel effective heat of combustion (kJA<g) 

The above calculations are based on principles developed in the Structural Design for Fire Safe~. 2001. 

Calculations are based on certain assumptions and have inherent limitations. 

The results of such calculations may or may not have reasonable predictive capabilities for a given 

situation, and should only be in~rpreted by an informed user. 

Although each calculation in the spreadsheet has been verified with the results of hand calculation, 

there is no absolute Quarantee of the accuracv of these calculations. 

ArPJ questions. comments, concerns, and suggestions, or to report an euor(s) in the spreadsheet, 

please send an email to nxi@nrc.gov or rro<:s3@nrc.gov. 
J-134

Additional Problems

1. Consider a pool fire caused by a 38.0 liters (10 gallons) spill of flammable liquid (kerosine oil)

in a 0.55-m (6.0-ft ) dike area in a compartment with a concrete floor. The kerosine oil is 2 2

ignited and spreads rapidly over the surface, reaching steady burning almost instantly.

Compute the HRR, burning duration, and flame height of the pool fire. The dimensions of the

compartment are 6.0 m wide x 6.0 m long x 3.7 m high (20.0 ft wide x 20.0 ft long x 12.0 ft high).

Two cable trays are located above the pool fire at heights of 2.15 m (7.0 ft) and 3.0 m (10.0 ft),

respectively. Determine whether flame will impinge upon the cable trays. Assume

instantaneous, complete involvement of the liquid pool with no fire growth and no intervention

by the plant fire department or automatic suppression systems.

2. Assume that heptane from a tank spills on a concrete floor forming a 113.0 m (1261.0 ft ) pool, 2 2

the distance from the center of the pool fire to the target edge is 30.0 m (98.0 ft). Calculate the

radiative heat flux of the flame at ground level with no wind using—

(a) Point Source Model

(c) Solid Flame Radiation Model

3. A trash fire with an HRR of 1,500 kW occurs in an NPP backup power battery room

protected with the fixed temperature heat detectors with an RTI of 165 (m-sec) . Calculate the 1/2

activation time for the detectors, using listed spacing of 3.05 m (20.0 ft) with a ceiling height of

4.60 m (15 ft). Assume that the detectors have an activation temperature of 57 °C (135 °F) and

the ambient temperature is 25 °C (77 °F).

4. A fire scenario arises from the failure of a 4,160V switchgear in a cable spreading room.

A stack of safety-related cable (IEEE-383 non-qualified PE/PVC) is located 4.6 m (15.0 ft)

horizontally from the 4,160V breaker. Assume that the breaker fire produces a maximum flame

heat flux 50 kW/m and the surface of the cable trays initially at 25 °C (77 °F). Calculate the 2

ig ignition time (t ) of IEEE-383 non-qualified PE/PVC cables.

5. A pool fire scenario arises from a rupture in an oil-filled transformer. This event allows the fuel

contents of the transformer to spill along a wall with an area of 1.4 m (15 ft ). A safety-related 2 2

f(wall) cable tray is located 5.5 m (18 ft) above the pool fire. Calculate the wall flame height (H )

of the fire, and determine whether flame will impinge upon the cable tray.

6. A fire scenario arises from a rupture in the housing of an auxiliary lube oil pump. This event

allows the fuel contents of the pump to spill along a wall with an area of 0.75 m (8.0 ft ). A 2 2

cable tray is located 3.0 m (10.0 ft) above the fire. Calculate the flame height of the line fire

f(wall line) (H ), and determine whether the flame will impinge upon the cable tray.

7. A fire scenario arises from a rupture in an oil-filled transformer in a facility. This event allows

the fuel contents of the transformer to spill along the corners of walls with an area of 0.55 m2

(6.0 ft ). A cable tray is located 5.5 m (18 ft) above the fire. Calculate the corner fire flame 2

he f(corner) ight (H ), and determine whether flame will impinge upon the cable tray. 
J-135

8. Consider a compartment that is 9.0 m wide x 9.0 m long x 3.7 m high (30.0 ft wide x 30.0 ft long

c c c

x 12.0 ft high) (w x l x h ) with a door vent that is 0.91 m (3.0 ft) wide x 2.15 m (7.0 ft) high

v v (w x h ). The fire is constant with an HRR of 1,500 kW. Compute the hot gas temperature

g

(T ) in the compartment as well as smoke layer height (z) at 5 minutes after ignition, assuming

that the compartment boundaries are made of 2.54 cm (1.0 in) thick gypsum board.

9. Consider a compartment that is 12.2 m wide x 12.2 m long x 3.0 m high (40.0 ft wide x 40.0 ft

c c c v v long x 10.0 ft high) (w x l x h ) with a door vent that is (4.0 ft) wide x (8.0 ft) high (w x h ).

The f gire is constant with an HRR of 2,000 kW. Compute the hot gas temperature (T ) in the

compartment as well as smoke layer height (z) at 3 minutes after ignition, assuming that the

compartment boundaries are made of 0.3048 (12.0 in) thick concrete.

10. Consider a compartment that is 15.25 m wide x 12.2 m long x 3.7 m high (50.0 ft wide x 40.0

c c c

ft long x 12.0 ft high) (w x l x h ) with a forced ventilation rate of 1,500 cfm. Calculate the hot

gas glayer temperature (T ) in the compartment for a fire size of 1,800 kW at 5 minutes after

ignition, assuming that the compartment boundaries are made of 2.54 cm (1.0 in) thick gypsum

board.

11. Consider a compartment that is 13.7 m wide x 15.25 m long x 3.35 m high (45.0 ft wide x 50.0

c c c

ft long x 11.0 ft high) (w x l x h ) with a forced ventilation rate of 1,800 cfm. Calculate the hot

gas layer g temperature (T ) in the compartment for a fire size of 2,200 kW at 8 minutes after

ignition, assuming compartment boundaries are made of 0.245 m (10.0 in) thick concrete.

12. Consider a pool fire caused by a 30.30liters (8.0 gallons) spill of flammable liquid (lube oil) in

0.38 m (4.0 ft ) dike area in a compartment with a finished concrete floor. The lube oil is ignited 2 2

and spreads rapidly over the surface reaching steady burning almost instantly. Compute the

HRR, burning duration, and flame height of the pool fire. The dimensions of the compartment

are 4.9 m wide x 3.7 m long x 3.0 m high (16.0 ft wide x 12.0 ft long x 10.0 ft high). Two cable

trays are located above the pool fire at heights of 1.8 m (6.0 ft) and 2.5 m (8.0 ft), respectively.

Determine whether flame will impinge upon the cable trays. Assume instantaneous, complete

involvement of the liquid pool with no fire growth and no intervention by the plant fire

department or automatic suppression systems.

13. A 75.7-liter (20.0-gallon) trash bag (transient) exposure fire source is located 2.5 m (8.0 ft)

beneath a horizontal cable tray. Assumed that the trash fire ignites an area of approximately

0.92 m (10.0 ft ) of the cable tray, and the cables in the tray are Id PE. Compute the full-scale 2 2

HRR of Id PE cable insulation. The bench-scale HRR of the Id PE type cable material is

1,071 kW/m .

2
J-136

14. Assume that heptane from a tank spills on a concrete floor, forming a 0.92 m (10.0 ft ) pool and 2 2

exposing a safety-related electrical cabinet in a corridor. The distance from the center of the

pool fire to the target (cabinet) edge is 3.7 m (12.0 ft). Calculate the radiative heat flux of the

flame to the electrical cabinet with no wind using—

(a) Point Source Model

(b) Solid Flame Radiation Model

15. Est p(centerline) imate the maximum plume temperature (T ) at the ceiling of a 4.6-m (15.0-ft) high

room above a 1,500-kW fire involving a 11⁄2-ft high stack of wood pallets in a 0.92-m (10.0-ft )

2 2

pallet area. Assume that the ambient temperature is 25 °C (77 °F).

16. A fire with = 3,000 kW occurs in a makeup pump room protected with a wet pipe sprinkler

system. Fire sprinklers are rated at 74 °C (165 °F) [standard response bulb with RTI 235

(m-sec) ] and are located 3.0 m (10.0 ft) on the center. The compartment ceiling is 5.5 m 1⁄2

(18.0 ft) high. Determine whether the sprinklers would activate, and if so how long it would take

for them to activate.

17. A fire scenario may arise from failure of a vital 480V AC breaker in a switchgear room. A stack

of safety-related cable (IEEE-383 non-qualified PE/PVC) is located 3.0 m (10.0 ft) horizontally

from the 480V AC breaker. Assumed that the vital breaker fire produces a maximum flame heat

flux of 30 kW/m and the surface of the cable trays is initially at 25 °C (77 °F). Calculate the 2

ig ignition time (t ) of IEEE-383 non-qualified PE/PVC cables.

18. A pool fire scenario arises from a rupture in an oil-filled transformer containing (5 gallons) lube

oil. This event allows the fuel contents of the transformer to spill along a wall with an area of

1.4 m (15.0 ft ). A safety-related cable tray is located 4.6 m (15.0 ft) above the pool fire. 2 2

Calculate the wall flame height of the fire, and determine whether flame will impinge upon the

cable tray.

19. A fire scenario arises from a rupture in the housing of a makeup pump containing 30.3 liters

(8 gallons) lube oil. This event allows the fuel contents of the pump to spill along a wall with an

area of 0.75 m (8.0 ft ). A cable tray is located 3.7 m (12.0 ft) above the fire. Calculate the 2 2

flame height of the line fire, and determine whether flame will impinge upon the cable tray.

20. A fire scenario arises from a rupture in an oil-filled transformer in a facility containing (6 gallons)

lube oil. This event allows the fuel contents of the transformer to spill along the corners of the

walls with an area of 0.55 m (6 ft ). A cable tray is located 4.3 m (14.0 ft) above the fire. 2 2

Calculate the corner fire flame height, and determine whether flame will impinge on the cable

tray.

21. Calculate the HRR necessary for flashover in a compartment that is 5.5 m wide x 6.0 m

c c c

long x 3.7 m high (18.0 ft wide x 20.0 ft long x 12.0 ft high) (w x l x h ), with an opening that

v v is 0.60 m (2.0 ft) wide x 1.83 m (6.0 ft) high (w x h ). Assume that the boundary material is

concrete and the door is open.
J-137

22. Calculate the HRR necessary for flashover in a cable spreading room (CSR) that is

15 c c c.3 m wide x 24.4 m long x 6.0 m high (50.0 ft wide x 80.0 ft long x 20.0 ft high) (w x l x h )

wi v v th a door opening 1.2 m (4.0 ft) wide x 3.0 m (10.0 ft) high (w x h ). The compartment

boundaries are made of concrete and the door is open.

23. Consider a compartment in a facility pump room that is 3.0 m wide x 2.7 m long x 2.5 m high

c c c

(10.0 ft wide x 9.0 ft long x 8.0 ft high) (w x l x h ). A fire starts with a constant effect of 75 kW.

Estimate the pressure increase attributable to the expansion of hot fire gases after 15 seconds,

assuming that the door is closed.

24. The licensee used UL Design No. 816 to protect a number of unrestrained beams. The

licensee’s quality assurance (QA) program verified that there is 6.35 cm (21⁄2 in) thickness of

fire protection insulation on all of the beams. The size of the tested beam was W12 x 26.

Determine whether the 6.35 cm (21⁄2 in) thickness of fire protection insulation is acceptable for

a beam that is W8 x 13.

25. A hydrogen line leaks 1 lb. of hydrogen in a turbine building. What is the worst case pressure

increase, blast wave, and TNT equivalent.

26. A compartment that is 15.25 m wide x 15.25 m long x 3.7 m high (50 ft wide x 50 ft long x 12 ft

high) has a hydrogen leak. What is the volume of gas needed for a deflagration.

Index-1

INDEX

Note: This is a brief index to quickly assist the user of this document. 

For a more thorough search, use the Search feature on the electronic .pdf version.

A

Abbreviations, G-1–G-11

Analogy of hydraulic and electric systems, B-11–B-12

B

Battery rooms hydrogen gas generation, 16-1–16-12

explosive concentration, 16-1

Fire Protection Code requirements, 16-7

flammability limit, 16-2

hydrogen and other gases concentration 

calculations, 16-2–16-9

ignition of hydrogen, 16-1–16-6

lower explosive limit, 16-1

prevention and control of combustion, 16-5–16-7

ventilation, 16-5, 16-10

Beam pockets, 2-23, 12-10

Burner, 3-9

gas, 3-9, 3-14, 17-1

Burning duration, 3-7

liquid pool fire, 3-8, 3-18

solid combustible, 8-1–8-3

Burning rate, 3-1, 3-3, 3-4, 3-6, F-10

C

Cable, A-1

damage threshold, 2-20, A-15–A-19

cable fire (Browns Ferry), A-1

cable material, 7-6, A-2, A-7, A-8

thermoplastic, A-7

thermosetting, A-8

configuration and construction classification, A-2

description, A-2 

function, 7-1, 7-2, A-3

insulation of, 1-6, 1-8, A-2–A-4

types of electrical, 2-20

Cable tray, 7-1–7-6, B-40

fire hazard, 7-1

burning mode, 7-2

factors of behavior in a fire, 7-2

scenarios, 7-2

type combustion reactions, 7-3

Calorimetry, oxygen consumption, F-12

See also Heat Release Rate; Flammability

Apparatus 3-3, F-12

Ceiling jet, See Compartment fire

Char–forming products, 2-17

Combustibles, 1-6 See also Fire hazard

fixed, 1-6–1-8, 2-19, 5-2

heat release rate, 2-19–2-21, 8-1–8-3

liquids

classification, B-17

definition, B-17

flashpoint, B-19

storage, B-20–22

transient, 1-6–1-8, 2-19, 3-3, 5-2

Combustion, 1-4, 1-5, 2-16, 6-3, F-15

Compartment fires

stages of, 2-1–2-6

fire-plume/ceiling jet, 3-12, 4-1

flashover, 13-1–13-9

ventilation, 2-4

pressure rise, 14-1–14-4

Conduction, See Heat transfer

Conductivity, See Thermal conductivity

Convection, See also Ventilation and Heat transfer

forced, 2-23, 2-24

natural, 2-23

Corner fire, See also Flame;

height entrainment coefficient, 4-4

Critical temperature, 5-2, 7-5, 17-5–17-10

Critical heat flux (CHF), 2-20, 5-2, 6-5–6-7, 6-12, 6-13

D

Decay stage, 2-17

Defense-in-Depth (DID)

objectives, 1-2 

Deflagration, See Explosions

Density, 2-10, F-21

Detontation, See Explosions

E

Electronics, thermal effect on, 2-22

Emissivity, 5-2–5-7, C-6, F-22

Energy,

radiant, 3-8, 5-2

electromagnetic, 5-1, F-47

Enclosure fire, See Compartment fire

Explosions, 15-1–15-15

characterization, 15-2, 15-3

confine and unconfined explosions, 15-4

definitions, 15-1, 15-2

effects on components, 15-3

effects on humans, 15-11

energy release and effects, 15-5–15-11

hazard associated with deflagration, 15-3

flammable mixture, 15-3

fuel vapor backdraft explosion, 15-4

limits, boundaries and range, 15-4

pressure increase due to explosion, 15-1

pressure increase estimation, 15-13

smoke explosion, 15-4

F

Fan, 2-4, 2-5

Fire classifications, B-13, B-14

extinguishing mechanism, B-16

Fire computational models, B-78–B-88 

Fire dynamics

definition, 1-1

Fire Dynamics Tools (FDTs), 1-1

process of fire development, 1-4–1-6

Fire events in nuclear power plants, H-1–H-33
Index-2

Fire extinguishing agents, B-16

carbon dioxide system, B-46–B-52

dry chemical, B-55–B-57

foam extinguisher, B-58–B-64

halon, B-41–B-46

Fire growth, B-1–B-10

flame and heat growth, C-5

Fire hazard, 1-1–1-9, 2-19

classification, B-14

common fires, 1-5

Fire Hazard Analysis (FHA), 1-3, 5-2

fire load, 1-6, F-26

fire location, 1-9

practice problems and solution, J-1–J-134

quantitative fire hazard analysis, I-1–I-17

sources, 1-4

Fire plumes, See also Compartment fire and Flame

buoyant axisymetric, 3-16, 4-1, 9-3

characteristics, 9-3

definition, 2-3, 9-1, F-45

regimes, 3-13, 9-3

centerline temperature, 9-4–9-7

virtual origin, 9-5

ceiling jet formation importance, 9-7

Fire protection, 1-1

inspection findings, 1-3

Nuclear Regulatory Commission (NRC)

documents, D-1–D-44

National Fire Protection Association codes,

E-1–E-13

program objectives, 1-1

risk-informed, performance-based

design basis, 1-9, F-49

Fire resistance, F-10

construction type, B-36–B-38

definition, C-6, F-10

fire barriers endurance ratings, C-9–C-11

test and standards, C-12–C-18

ratings, B-8–B-11

Fire scenario, 2-19, F-28

Flame, 3-10

categories, 3-10–3-12

spread rates of flammable/combustible,

3-6, 6-10–6-11

height, 3-8, 3-16

liquid pool fire, 3-17

wall fire, 4-1–4-3

line fire, 4-1–4-3

corner fire, 4-1, 4-4

hydrogen, 3-8

oxygen-acetylene, 3-12

pulsing behavior, 3-12, 3-16

regimes, 3-13, 4-1

spread rates of flammable/combustible liquid, 3-6

temperature, 3-16–3-18, 5-2

adiabatic, 3-19, 3-20

Flammable gases

classification, B-28

deflagration-to-detonation transition (DDT), B-30

explosive limits, B-30

explosion prevention methods, B-30, B-31

flammable limits, B-28

hydrogen, B-33, B-34

Flammable liquids, B-17

classification, B-17

definition, F-31

flashpoints, B-17

storage, B-20, B-21

Flashover, 13-1–13-9

definitions, 13-3, F-32

experimental observations, 13-4

flashover prediction in compartments, 13-1–13-6

incipient period, 13-1

methods to predict HRR compartment flashover,

13-5, 13-6

methods to predict temperature compartment

 flashover, 13-7

physical characteristic, 13-3

stages, 13-3

Fuel, 3-1 See also Combustible & hazard materials

chemistry, 3-7

hydrocarbons, 3-3

limited fires, 2-4

liquid fuels, 1-8, 6-2

loading, 3-1

solid fuels, 6-1, 6-2

thermal properties, 8-2

Fuel ignition, 6-1–6-13

by radiative heat flux, 6-12, 6-13

ignition time, 6-1, 6-4, 6-7, 6-8, 6-10, 15-10

ignition temperature, 6-10, 6-11, 15-10

flash point, 6-1

piloted ignition, 6-1

auto-ignition, 6-1

heat flux sources, 6-4

thermal response parameter (TRP), 6-5, 6-6

G

Gases, 2-14

combustion toxic effluents, B-78

hot, 2-14, 3-16

layer, 2-8, 2-25

plume of hot, 3-16

temperature, 2-8, 2-13

self ignite, 2-6

H

Heat capacity, 2-10, F-35

Heat detectors, 12-1–12-10

response time index, 12-6 –12-8

operational temperature limits, 12-1–12-2

heat detector types, 12-2–12-5

activation temperature calculation, 12-5

Heat of combustion, 2-20, 3-3–3-6, F-35
Index-3

Heat release rate (HRR), 2-16–2-25

cable trays, 7-3, 7-4

curves, 2-18

data tables, 2-20–2-22

liquid pool fire, 3-1–3-4

bench-scale, 6-6, 7-3, 7-4

flammability apparatus, 6-5

Heat resistance of target fuel, C-4

Heat sources, C-2

heat intensity, C-2, C-3

heat flux, C-2, C-3

heat quantity, C-2

duration, C-2, C-3

incident heat, C-3

Heat transfer, 5-1

coefficient, 2-9–2-13

radiative (radiation), 3-17, 4-2, 5-2

convection, 5-1

conduction, 5-1

Horizontal fire, See Pool fire

I

Ignition threshold, 2-22, A-11–A-14

Incident heat flux, 2-10, 5-2, C-3, F-67

Inspection findings, 1-3

J

Jacketing materials, See Cable

L

Line fire, 4-2 See also Flame; height

geometry, 4-2, 4-3

entrainment coefficient, 4-2

M

Mass loss rate, 2-4, 3-3, 3-5, F-41

Metal combustion properties, B-29–B-31

extinguishing agents, B-31

melting, boiling and ignition temperature, B-30

N

Noncombustible ceiling, 4-4

Nuclear power plants,

fire hazard analysis, 1-3

O

Oxygen consumption, 3-3, 6-5, F-12

P

Performance-based, See Fire protection

Point source, See Radiation models

Pool Fires, 3-1–3-8, 3-14, 5-4

burning duration, 3-8

burning modes, 3-4

circular, 3-18

nuclear power plants (NPP), 3-4, 3-5

non-circular, 3-18, 5-4

Post-fire safe shutdown, 7-1

Post-flashover vented fire, See Compartment fire

Pre-flashover vented fire, See Compartment fire

Pyrolysis, 6-3, 7-3–7-5, F-46

Q

Quasi-steady balance, 2-8, 2-23

R

Radiation, 5-2 See also Heat transfer

spherical source, 5-3

Radiation models, 5-1

configuration factor, 5-2

point source, 5-2–5-5

solid flame, 5-4–5-17

Risk informed, See Fire protection

S

Scenario, See Fire scenario

Smoke detector, 11-1–11-11

alarm condition, 11-6

performance, 11-1–11-3

response parameter, 11-8

response time, 11-1

type of smoke detectors, 11-3–11-6

Smoke layer, 2-14–2-16

cool gas layer, 2-14

filling, 2-12–2-15

height estimation, 2-13, 2-17, 2-23

hot gas layer, 2-13, 2-14, 2-23

interface position, 2-15

visibility through smoke, 18-1–18-5

Smoldering, 6-3, F-55

Solid flames, See Radiation model

Sprinkler, 2-22, 3-16, 10-1–10-12

heat transfer characteristics, 10-3

installation configuration, 10-2

main function, 10-3

operating principles, 10-3

plume interaction, 10-13

response time, 10-1

types of automatic sprinklers, 10-1–10-3

sprinkler dynamics, 10-4

operational temperature, 10-5–10-8
Index-4

Spills, 3-18

liquid fuel, 3-5, 4-1, 5-3

fuel volume of, 3-18, 4-5

fuel area, 3-18, 4-5

Structural building components, 17-1

building fire resistance rating, 17-3, 17-4

fire walls and fire barriers, 17-7–17-8

Structural steel, 17-1

beam, 17-16, 17-17

column, 17-1

failure criteria, 17-6

fire resistance calculation, 17-12–17-16

fire resistance classification, 17-1

fire resistance coatings, 17-9–17-12

protection methods, 17-4, 17-5, 17-13,

scenarios, 17-3, 17-4

temperature limits, 17-6

unloaded columns criteria, 17-4

unprotected steel columns, 17-2–17-12

numerical methods for temperature increase,

17-20–17-23

 T

Tail stage, 2-17

Thermal capacity, 2-10, 2-11, F-35

Thermal conductivity, 2-10, 2-11, F-64

Thermal feedback, 2-1, 2-24, 13-6

Thermal Inertia, 2-10, 2-11, F-64

Thermal insulators, 2-10, 6-5

Thermal penetration time, 2-10, F-65

Thermal radiation, 5-1–5-16

field of flames, 5-3

hazard, 5-3

Thermoplastic, See Cable

Thermosetting, See Cable

Turbulent diffusion flame, 3-14, 4-5

V

Ventilation, 2-4

forced ventilation, 2-4, 2-5, 2-12, 2-13, 2-24

limited or controlled, 2-4

make up air, 2-4

natural ventilation, 2-8–2-12, 2-15, 2-24

Vulnerability

Fire-Induced Vulnerability Evaluation

Method (FIVE), 2-19, 5-2
BIBLIOGRAPHIC DATA SHEET

(See instructions on the reverse)

NRC FORM 335

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