NBSIR 76-1052

Naval Shipboard Fire Risk Criteria - Berthing Compartment Fire Study

and Fire Performance Guidelines

B. T. Lee and W. J. Parker

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

September 1976

Final Report

Prepared for Ship Damage Prevention and Control

Naval Sea Systems Command

Department of the Navy

Washington, D. C. 20362

NBSIR 76-1052

NAVAL SHIPBOARD FIRE RISK CRITERIA - BERTHING COMPARTMENT FIRE STUDY

AND FIRE PERFORMANCE GUIDELINES

B. T. Lee and W. J. Parker

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

September 1976

Final Report

Prepared for Ship Damage Prevention and Control

Naval Sea Systems Command

Department of the Navy

Washington, D. C. 20362

U.S. DEPARTMENT OF COMMERCE, Elliot L. Richardson, Secretary

Edward O. Vetter, Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

CONTENTS

Page

LIST OF FIGURES V

LIST OF TABLES vii

NOMENCLATURE viii

SI CONVERSION UNITS X

Abstract 1

1. INTRODUCTION 1

2. FACILITIES AND EXPERIMENTAL TESTS 3 2.1. Full Size Compartment Fires 3 2.2. Quarter-Scale Compartment Fires 6 2.3. Small Laboratory Fire Tests 6 2.3.1. Radiant Panel Test Apparatus 6 2.3.2. Flooring Radiant Panel Test 6 2.3.3. Potential Heat Test 7 2.3.4. Smoke Density Chamber 7 2.3.5. Heat Release Rate Calorimeter 8 2.3.6. Ease -of -Ignition Test 8

3. ANALYSIS 8 3.1. Prediction Model for Potential Fire Hazard 9 3.2. Modeling Principles and Preliminary Studies 13

4. RESULTS AND DISCUSSION 15

4.1. Preliminary Experiments with the Model 15

4.1.1. Ignition Method 15

4.1.2. Arrangement of Bedding 16

4.1.3. Mattress Thickness 16

4.1.4. Bunk Placement and Openness 16

4.1.5. Room Ventilation 16

4.1.6. Thermal Inertia of Overhead Linings 17

4.1.7. Rate of Fuel Supply 17

4.2. Model and Full-Scale Compartment Fires 17

4.2.1. Discussion of Individual Tests 23

4.2.1.1. Tests Ml to M4B and 1 to 4B 23

4.2.1.2. Tests M5 to M7 and 5 to 7 23

4.2.1.3. Tests M8, M9 and 8 to 11 24

4.2.2. Supporting Measurements 26

4.2.2.1. Thermal Radiation 26

4.2.2.2. Temperature Distribution in Compartment . . 27

4.2.2.3. Compartment Ventilation 27

4.2.2.4. Oxygen Depletion and Carbon Monoxide. ... 28

4.2.2.5. Smoke Optical Density 28

4.2.3. Heat Balance for Compartment 29

5. LABORATORY FIRE TEST DATA 30

6. DESIGN GUIDELINES 3 3 6.1. General 33

6.2. Rate of Heat Release and Flame Spread 34

iii
CONTENTS (cont'd)

Page

6.3. Potential Heat 36

6.4. Time to Ignition 36

6.5. Smoke Production 37

6.6. Toxicity of Combustion Products 38

6.7. Summary of Criteria , 40

7. CONCLUSIONS 40

8. REFERENCES 4 2 APPENDIX - TEST OBSERVATIONS 67

iv
LIST OF FIGURES

Page

Figure 1. Plan View of Two Compartment Arrangements Showing

Locations of Furnishings and Instrumentation 44

Figure 2a. A Typically Furnished Navy Compartment Fire Test and

Locker Prior to Ignition 45

Figure 2b. Description and Dimensions of 3-Man Berthing Unit ..... 46

Figure 3. Air Temperatures Inside Compartment — Lauan Wall,

Gypsum Board Ceiling 47

Figure 4. Velocity Profiles in Doorway at 10 Minutes for Fulland Quarter-Scale Enclosures with Gypsum Board Linings ... 48

Figure 5. Temperatures in Upper Part of Compartment for Fire Tests 1 and Ml 49

Figure 6. Temperatures in Upper Part of Compartment for Fire Tests 2 and M2 50

Figure 7. Temperatures in Upper Part of Compartment for Fire Tests 3A

and M3A 51

Figure 8. Temperatures in Upper Part of Compartment for Fire Tests 3B

and M3B 52

Figure 9. Temperatures in Upper Part of Compartment for Fire Test 4A. 53

Figure 10. Temperatures in Upper Part of Compartment for Fire Tests 4B

and M4B 54

Figure 11. Temperatures in Upper Part of Compartment for Fire Tests 5 and M5 55

Figure 12. Temperatures in Upper Part of Compartment for Fire Tests 6

and M6 56

Figure 13. Temperatures in Upper Part of Compartment for Fire Tests 7 and M7 57

Figure 14. Temperatures in Upper Part of Compartment for Fire Tests 8 and M8 58

Figure 15. Temperatures in Upper Part of Compartment for Fire Tests 9 and M9 59

Figure 16. Temperatures in Upper Part of Compartment for Fire Test 10 . 60

Figure 17. Temperatures in Upper Part of Compartment for Fire Test 11 . 60

Figure 18. Thermal Radiation Incident on Deck as Function of Upper

Air Temperature 61

V
LIST OF FIGURES (cont'd)

Page

Figure 19. Vertical Temperature Profile in Compartment Fire Tests 4B

and M4B 62

Figure 20. Vertical Temperature Profile in Compartment Fire Tests 9 and M9 6 3 Figure 21. Temperature Rise in Doorway Exhaust Versus Oxygen

Depletion for Test 9 64

Figure 22. Temperature Rise in Doorway Exhaust Versus Oxgyen

Depletion for Test 11 64

Figure 23. Temperature Rise in Doorway Exhaust Versus Oxygen

Depletion for All Tests Having Opened and Partially

Opened Doorways 65

Figure 24. Oxygen Depletion Versus Carbon Monoxide Concentration

in Doorway Exhaust for the Compartment Fire Tests 65

Figure 25. Smoke Obscuration in Full-Scale Compartment Fire Tests ... 66

vi
LIST OF TABLES

Page

Table 1. Compartment Fire Tests 4 Table 2. Bedding and Locker Materials in Full Size Compartment

Fire Tests 5 Table 3. Results of Model Tests with Three Different Overhead

Linings 18

Table 4. Summary of Results of Full Size Compartment Fires

a. At Times of Peak Upper Air Temperatures 19

b. Peak Values of Other Measurements and Their

Corresponding Times 20

Table 5. Summary of Results of Quarter-Scale Compartment Fires

a. At Times of Peak Upper Air Temperatures 21

b. Peak Values of Other Measurements and Their

Corresponding Times 22

Table 6. Heat Losses from Compartment 29

Table 7. Results from the Five Laboratory Fire Tests 31

Table 8. Results of Corner Fire Tests with Gypsum Board Ceilings ... 32

Table 9. Estimated Potential Concentrations of Selected Gases

from Berthing Compartment Fires and Their Toxicological

Limits 39

Table 10. Selection Criteria for Interior Finish in Berthing Quarters . 41

vii
NOMENCLATURE

A floor area

A„ potential bulkhead area contributing to the fire

B A^ burning area of i-th combustible

A^ potential overhead area contributing to the fire

A^ area of heated surface in upper part of compartment

B mass burning rate

Bg mass burning rate required to consume all of the incoming air

C heat capacity

heat capacity at ambient temperature

D density of ambient air

f ratio of effective radiating area to the area of the heater surface, A^,

in the upper part of the compartment

F flame spread factor

h height of doorway

I flame spread index •

, s K thermal conductivity

L effective heat transfer coefficient equal to ratio of heat losses

per unit area and the temperature rise, (T^ - T^)

L heat loss coefficient by conduction

c heat loss coefficient by radiation

Q net heat of combustion of burning materials

heat release rate per unit area of i-th combustible

q^ maximum one minute averaged rate of heat release per unit area of material

t time

Tg temperature of the hot air in the upper part of compartment

ambient temperature of air

temperature of hot surfaces in upper portion of compartment

V Volume

V Volumetric flow rate of incoming air w width of doorway

viii
thickness of walls and ceiling

emissivity of surface

characteristic temperature rise of air in upper part of room

0* = QB /DC V

s' o Stefan-Bol tzmann constant

density of material

ix
SI CONVERSION UNITS

In view of the present accepted engineering practice in this country,

common U.S. Units of measurement have been used throughout this report. In

recognition of the position of the United States as a signatory to the General Conference on Weights and Measurements which gave official status to the

metric SI system of units in 1960, we assist the readers interested in making

use of the coherent system of SI units by giving conversion factors applicable

to the U.S. units used in this report.

Length

1 in

1 ft

0.0254 meter

0.3048 meter

Mass

1 lb 0.4536 kilogram

Temperature

Temperature in °F = 9/5 (temperature in °C) + 32 °F

Energy

1 Btu = 1054. 6 joules

Power

1 Btu/s = 1054.6 watts
NAVAL SHIPBOARD FIRE RISK CRITERIA - BERTHING COMPARTMENT FIRE STUDY AND FIRE PERFORMANCE GUIDELINES

B. T. Lee and W. J. Parker

Abstract

Judicious application of shipboard materials and choice of

compartment furnishings can significantly reduce the threat of

serious fire on board ship. Unfortunately, the fire performance

of materials is currently difficult to ascertain from laboratory

fire tests on the materials. Full size and quarter-scale compartment fires in conjunction with an analytical treatment were performed to obtain an improved understanding of the relationships

between the laboratory fire test assessment and the observed

behavior of materials in actual fires. The compartment fire

experiments indicated that the temperature of the hot air layer

below the ceiling is a suitable quantitative measure of the level

of fire buildup in a compartment. When this temperature exceeds

700 °C there is sufficient radiation from the hot air layer and

the heated upper surfaces to cause ignition of all combustible

materials in the compartment. For a3x3x2.1m (10x10x7

ft) space lined with asbestos millboard having a 0.69 x 1.9 m (27 x 75 in) open doorway, a heat production rate of about 72 kW/m^

(6.3 Btu/s/ft^) of deck area is enough to attain this condition.

Fires in some bunk configurations alone could exceed this critical

rate of heat generation. Ventilation and its points of application

were found to be very important considerations. Observations of

the fire scenarios in the compartment tests along with an empirical

and analytical analysis of fire growth in compartment spaces have

resulted in an improved application of the fire test ratings.

Consequently more rational design rules for fire safe material

usage have been developed taking into account the ignitability

,

flame spread, rate of heat release, potential heat and smoke

generation potential of materials. The study also indicated the

practicality of using quarter-scale fire tests for studying fire

performance in full size compartments.

1. INTRODUCTION

An accidental fire represents a potential major hazard to which a Naval

ship is in constant danger of exposure. Effective ship design and damage control features permit most shipboard fires to be quickly brought under control

with minimal property loss and little threat to the life safety of the crew. One of the most important elements of ship design is the judicious selection

of materials for the ship's interior finish and choice of compartment furnishings to minimize the spread of fire, generation of smoke and gaseous combustion

products, and the amount of additional fuel contributed to an on-going fire.

The present Navy fire performance requirements given in MIL. STD 1623 for

interior finish materials and furnishings [I]-'- provided a significant improvement in the selection of fire safe materials. This military standard offered

laboratory fire test limits on the surface flammability and smoke potential of

many categories of materials. Unfortunately, the fire performance of materials

is presently difficult to assess solely on the basis of laboratory tests.

Numbers in brackets refer to the literature references listed at the end

of this paper.

1
Ideally, the fire behavior of any one material or group of materials should be

evaluated along with the room and its furnishings so that the combination will

have a low probability of full involvement in the event of an accidental ignition. Prerequisite to this approach is a better understanding of the fluid

dynamic, thermal, physical and chemical factors important in controlling the

growth and spread of fire and combustion products within compartments. Concurrent with the need for fuller understanding of the fire phenomena is an improved interpretation and application of present test methods and/or better

laboratory test methods which can provide meaningful correlation with fire

buildup in the compartment. Some progress has been made in this direction

with the on-going research on room fire growth at the Bureau of Standards [2].

In the latter study a variety of wall and ceiling panels in a full-scale room

corner has been exposed to a wood crib fire to evaluate their contribution to

room fire buildup. The results of these fire tests were compared with laboratory tests of the ignitability , flame spread, rate of heat release and smoke

generation potential of the materials.

The shipboard fire research program for the Navy has also been designed

to help fulfill the above needs. The project was structured in three phases.

During the first phase of this project a review was made of the existing

specifications for shipboard construction materials and the test methods used

to determine fire performance. The survey indicated that a wide variety of

tests were being used in conjunction with different criteria to evaluate

materials designated for identical or similar usage.

A set of three standardized tests on surface f lammabili ty , fuel contribution and smoke generation were recommended to replace a variety of tests in

the Navy's material specifications. Specifically, these tests were the ASTM E162 radiant panel, the potential heat test, and the smoke density chamber.

All of these tests had been developed previously at the Bureau. The acceptance criteria recommended for the tests depended on the designated usage of

the material.

It was also indicated that ignitability and the rate of heat release were

important in determining the potential fire hazards of materials and that the

development of suitable laboratory test methods for these properties should be

undertaken in the second phase of the program. Furthermore, tests should be

conducted in full-scale compartments with selected lining materials whose fire

properties would also be measured by these five tests. This would establish

the ability of the laboratory tests and their associated acceptance levels to

provide a valid measure of fire risk without excessive restrictions on the

materials that could be used aboard ship. This information was included in

the Phase I report [3]. ,

, . An ease-of-ignition test, which measures the exposure time required for

sustained ignition by flame contact, and a heat release rate calorimeter were

developed and tested on a variety of materials under Phase II. Their operations have been described in progress reports [4,5].

Phase III, covered in this report, has had the following objectives:

(1) to determine the physical conditions and interior materials

likely to lead to full fire involvement of a furnished

compartment and potential spread to other shipboard areas, and

(2) to improve fire risk criteria for material usage on board ship.

This report describes the full-scale compartment fires and quarter-scale

modeling of these fires and includes material ratings with the above five

laboratory fire tests and their comparison with their contribution to fire

growth observed in the compartment fires. A brief description of a new test

being developed for evaluating the flammability of floor and deck coverings

has also been included. In addition, a preliminary analytical method is given

2
for predicting the fire hazard potential of full size furnished compartments.

Starting with a basic heat balance for a compartment containing combustible

furnishings and interior linings, the analysis section evaluates the rates of

heat generated, absorbed and lost and establishes a method for calculating

temperatures in the compartment. This assists in establishing a basis for

fire safe guidelines for construction material usage. This report also

includes improved fire risk criteria for material selection.

2. FACILITIES AND EXPERIMENTAL TESTS

2.1. Full Size Compartment Fires

The berthing compartment fire tests were conducted in a 3.1 x 3.1 m (10 x 10 ft) room having a 2.1 m (7 ft) drop ceiling and a 0.69 x 1.9 m (27 x 75 in)

doorway, figure 1. The room was only one-half of the smallest size normally

encountered aboard ship, but it was desirable to make this reduction in order

to use the existing burnout room at NBS . The compartment was located within a large building, so that the effects of wind and temperature extremes were

eliminated. Two walls were lined with 2.5 cm (one inch) fiberglass. The

other sides were covered with 1.59 mm (1/16 in) decorative aluminum panels

over 5.1 x 10.2 cm (2 x 4 in) steel studs 40.6 cm (16 in) apart. The decorative coatings on the aluminum were either vinyl or melamine. The deck was

0.64 cm (1/4 in) mild steel over a brick floor. A sliding door having a 0.093

(one foot square) exhaust port was used. In situations where the doorway

was partially or fully opened, the exhaust port was closed. When the door was closed the exhaust port was open. Provisions for forced air ventilation into

the compartment were available at a ceiling vent at the rear of the room and

at terminals located at each bunk, figure 2. The total flow rate of this air was roughly 4.5 m^/min (160 ft^/min) . A viewing port was also located on one

wall.

In line with the reduction in compartment size the contents of the space

was restricted to the needs of three crew members. These contents include a modular crew berth three high, and a large fully opened locker, figure 2. The

latter was filled with 33 kg (72 pounds) of simulated clothing. The bedding

for each crew member weighed 14.5 kg (32 pounds) and was in considerable disorder to promote a rapid growth of the fire, simulating worst case conditions.

Table 1 lists the interior linings used in this study. Other furnishings such

as the locker contents, bedding and clothes are indicated on table 2.

Measurements made to characterize the thermal environment in the compartment included ceiling and wall temperatures, vertical temperature profile down

from the center of the ceiling, air temperature near the top of the doorway,

radiation incident on the deck, air inflow velocity near the bottom of the

doorway and the weight loss rate of the bedding. Auxiliary measurements to

fully describe the fire included smoke obscuration, oxygen and carbon monoxide

concentrations at the top of the doorway and inside the compartment. Temperatures were measured with 0.025 cm (0.010 in) diameter chromel-alumel thermocouples. The thermal radiation incident on the lower portion of the room was monitored with a water-cooled Gardon-type total heat flux gage. Crumpled up

newsprint on the deck was also used to indicate if and when the irradiance was sufficient to ignite light combustible materials. A hot wire anemometer was

used to measure the air inflow velocities. A chemical cell and infrared analyzer were used to record the oxygen and carbon monoxide, respectively. Weight

loss, i.e., fuel depletion, in the berths was measured by suspending the three- man unit with an overhead pulley connected to a load cell transducer. The

location of all instrumentation in the compartment is indicated in figure 1.

Thirteen test arrangements were considered and are indicated in table 1.

3
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Table 2. Bedding and Locker Materials in Full

Size Compartment Fire Tests

Item Weight (lb)

a Bunk Contents

3 Ph iplcpn FPr^1~hf^T" Pill owe; 11. 5

12

* Cotton Sheets

3 Wool Blankets 11 n

3 3-inch Thick Neoprene

Mattress and Fire

Retarded Cotton Ticking

^ ^ .

3 Cotton Mattress Covers 5.5

3 Cotton Pillow Cases 0.7

Total Bedding 96.7

D13 . Locker Contents

** Cotton Rags and Cotton Waste 68.0

1 Wool Blanket 3.7

Total Locker Materials 71.7

* Two sheets per bunk plus two extra sheets per bunk to simulate pajamas or other clothing.

Distributed throughout locker.

5
2.2. Quarter-Scale Compartment Fires

The model test enclosure was a one-quarter-scale replica of the full size

compartment except for the doorway width, which had to be reduced by only onehalf in order to secure the proper air inflow. This model enclosure consisted

of a steel shell with interior lining materials identical with those of the

full-scale test. Several preliminary experiments with a gas burner on the

center of the floor and with a noncombustible interior lining of 2.5 cm (one

inch) thick asbestos insulation board were conducted to assist in the selection,

development and placement of adequate instrumentation to characterize the fire

behavior in the model and in the full-scale compartment. Instrumentation in

the model was similar to that used in the full size compartment except that

smoke and gas analysis inside the enclosure and the wall and floor temperatures

were not monitored.

2.3. Small Laboratory Fire Tests

2.3.1. Radiant Panel Test Apparatus

The ASTM E-162 radiant panel test [6] requires a 15.2 by 45.7 cm (6 by

18 inch) specimen, facing and inclined 30 degrees to a vertically-mounted,

gas-fired radiant panel. The energy output of the panel is controlled to be

the same as that from a blackbody of the same dimensions operating at a temperature of 670 °C (1,238 °F) . Ignition is caused by a pilot flame just above

the upper edge of the test specimen and observations are made of the progress

of the flame front down the specimen surface, as well as the temperature-rise

of the thermocouples in a stack supported above the test specimen. The test

is terminated when the flame reaches the end of the specimen or in 15 minutes,

or whichever time is less. The flame-spread index, Ig, is computed as the

product of the flame-spread factor, Fg, and the heat evolution, Qg, or Ig = FgQg, where

= 1 +

1t3 tq-t, ti2-t< t 1 5~t 1

2

+ and Q aAT/6

the symbols ts to tis correspond to times in minutes from specimen exposure

until arrival of the flame front at a position 7.6 to 38.1 cm (3 to 15 inches),

respectively, along the length of the specimen. The value of a in the relation

for the heat evolution is a constant arbitrarily chosen to yield a flame-spread

index of approximately 100 for red oak. The quantity AT is the observed maximum stack thermocouple temperature-rise over that observed with an asbestoscement board specimen, and 6 is the maximum stack thermocouple temperature-rise

for unit heat imput rate to the calibration burner.

This test procedure has been adopted as an ASTM standard method for

measuring the flammability of building materials. Flame-spread index values

vary from zero for asbestos-cement board to approximately 100 for uncoated

wood and can be considerably greater for highly flammable materials.

2.3.2. Flooring Radiant Panel Test

This test is under development and is intended to replace the ASTM E-162

method for flammability testing of deck and floor coverings. The flooring

radiant panel test [7] measures the critical radiant flux for flame spread

of horizontally-mounted floor covering systems exposed to a flaming ignition

source in a graded radiant heat energy environment. Critical radiant flux is

the level of incident radiant heat energy on the specimen surface at the most

distant flame-out point. The specimen can be mounted over under layment , bonded

to a simulated structural floor or otherwise installed in a typical and representative way.
The radiant energy source is a premixed air gas fueled panel inclined at

30 degrees to and directed at a horizontally-mounted 22.2 cm (8.75 in) by

104.1 cm (41 in) specimen. The radiant panel generates an energy flux distribution ranging from a maximum of 1.0 W/cm^ (0.88 Btu/s/ft^) to a minimum of

0.1 W/cm^ (0.09 Btu/s/ft^) under the low panel temperature setting of between

490 to 510 °C (914 to 950 °F) and from 0.2 to 2.4 W/cm^ (0.18 to 2.1 Btu/s/ft^)

in the high panel temperature range of 660 to 680 °C (1,220 to 1,256 °F) . Test results are reported as the critical radiant flux, W/cm^ , for flame-out.

2.3.3. Potential Heat Test

The potential heat test [8] provides a quantitative measure of the total

heat released under typical fire exposure conditions without regard to the

rate at which the heat is released.

The heat of combustion, Q^,, of a sample of the material measured by an oxygen bomb calorimeter, after it has been exposed to a "standarized fire"

(2 hours in a muffle furnace at 750 °C (1,382 °F) ) is compared with the heat

of combustion Q of an unexposed sample. The potential heat Q|^, is given by

Q. = Q - R Q"^r

where R is the fractional weight remaining after the exposure.

Determinations may be made on simple materials, or on composite assem- blies of materials from which a representative sample can be taken and pulverized into a homogeneous mixture.

2.3.4. Smoke Density Chamber

The smoke density chamber [9] is a 0.51 m^ (18 ft^) closed cabinet in

which a specimen 58.1 cm^ (three inches square) is supported vertically in a holder and is exposed to an irradiance of 2.5 W/cm^ (2.2 Btu/s/ft^) under one

of two exposure conditions, designated as "flaming" or "non-flaming" (smoldering). For each specimen, the combustion generated smoke accumulates within

the chamber and the reduction of light transmission during the test is reported

in terms of the optical density of the smoke.

The method assumes the applicability of Bouguer's law to the attenuation

of light by smoke, and the quantity of smoke is therefore reported in terms of

optical density rather than light absorption. Optical density is the single

measurement most characteristic of a "quantity of smoke" with regard to visual

obscuration. To take into account the optical path length, L, the volume of

the chamber, V, and the specimen surface area producing smoke. A, a specific

optical density is defined as Dg = V/LA (log^Q 100/T) , where T is the percent

light transmittance and the term in parenthesis is the optical density.

During the smoke chamber tests, indications of the concentrations of CO,

HCl, HCN, NO + NOj and SO^ are obtained by drawing a sample of the gas mixture

through commercial colorimetric detector tubes. Essentially, a colorimetric

tube is a small-bore glass tube containing a chemical packing which changes

color when exposed to a specific component of a gas mixture, and the length

of color stain is related to the concentration of that component, for a given

quantity and rate of gas flow.

7
2.3.5. Heat Release Rate Calorimeter

The heat release rate calorimeter [5] measures the rate of heat generation

for building materials exposed to radiant fluxes up to 10 W/cm^ (8.8 Btu/s/ft'')

with a response time of a few seconds. A 11.4 x 15 cm (4-1/2 x 6 in) specimen,

up to 2.5 cm (1 in) in thickness, is oriented vertically in front of gas fired

radiant panels lining three sides of a combustion chamber. The radiation

comes from the surface of these panels whose temperatures may be varied

between 627 and 1,027 °C (1,160 and 1,880 °F) to produce the desired irradiance level on the sample. The edges of the specimen are shielded by an insulated holder. The rear surface of the specimen is exposed to a 2 . 5 cm (1 in)

thick water-cooled brass block. Four adjustable standoff screws prevent the

sample from contacting the water-cooled block and position the front surface

of the specimen flush with the front of the holder. This configuration

represents a section of a burning wall where the back surface of the wall is

exposed to a relatively cool surface. The heat released from the rear surface

is absorbed by the block and is calculated from the flow rate and temperaturerise of the cooling water. Air for combustion of the sample passes up through

the porous floor of the chamber.

The fast time response of the calorimeter to the heat leaving the front

surface of the specimen is achieved by maintaining the instrument at a constant

temperature so that there is little heat loss between the combustion products

and the apparatus itself. The constant temperature operation is accomplished

with an auxiliary burner whose fuel supply is regulated by an automatic temperature controller. An increase in heat due to the burning of the specimen is

then compensated by a decrease in the fuel flow rate. The calorimeter measures

this decrease in the rate of flow of the fuel, which is also proportional to

the rate of heat release of the specimen.

2.3.6. Ease-of-Ignition Test

The ease-of-ignition test [4] measures the exposure time required to produce flaming ignition of building materials in contact with flames from incidental or low energy fires. Two specimens 14.0 cm (5-1/2 in) wide and 15.2 cm

(6 in) high face each other 2.2 cm (7/8 of an inch) apart. Natural gas is then

introduced into the gap and is ignited with a coiled Nichrome heater wire. The

exposing flame passes between the specimen surfaces and extends about 25.4 cm

(10 in) above them. The heat flux from the flame source averages 3.3 W/cm^

(2.9 Btu/s/ft^) with a variation of 40% over the height of the specimen.

The object of the test is to determine the flame exposure time required

to produce ignition in at least one of the two specimens. Ignition is defined

here as the persistence of flames for one second or longer any place on the

specimen following the curtailment of the gas flow.

3. ANALYSIS

The study of compartment fires involves the investigation of many parameters affecting the process of fire development, because of the complexity of

the fire jrowth phenomena, which involves combustion chemistry, heat transfer,

and fluid dynamics. An analytical technique for predicting the fire hazard

potential of a compartment can outline the more pertinent parameters to be

measured or observed during the compartment fire tests. It can provide a framework in which to analyze the actual fire performance of a material and

relate it to the laboratory ratings for that material. Furthermore such a prediction method can offer insights into scaling possibilities for experimental work on a reduced size.

Small-scale modeling is necessary in order to permit a large number of

experiments to be conducted under controlled laboratory conditions and at

reduced cost. Under this phase of the program, modeling techniques were also

^: 8
devised, and a quarter-scale model of the full-scale compartment was constructed. Some corner tests, which were run in the burnout room on another project

[2], were duplicated in the model. Results from these model tests showed good

simulation of the full size behavior [10]

.

A simplified prediction scheme for fire buildup in an enclosure along

with modeling principles and preliminary studies on reduced scale experiments

are discussed in this section.

3.1. Prediction Model for Potential Fire Hazard

A simplified analytical technique for predicting the fire hazard potential

of a compartment has been developed on this project and has been reported by

Parker and Lee [10] . A description of the prediction model is the subject of

this section.

A complete analytical description of the compartment fire is too complex

for exact solution. It is necessary to make many simplifying assumptions and

approximations. In order to predict the magnitude of fire severity there must

be some quantitative measure of the level of fire buildup in a compartment.

A suitable measure appears to be the upper air temperature which is the temperature of the hot air layer below the ceiling. The hot air layer, as the term

is used here, includes flaming and non-flaming gaseous pryolysis and combustion

products. When this upper air temperature reaches 500 °C (932 °F) there is a rapid pyrolysis and ignition of all combustibles in the upper part of the

compartment. When it exceeds 700 °C (1,292 °F) there is sufficient radiation

emitted from the heated upper surfaces or hot smoke layer to cause ignition of

all combustible materials in the lower part of the compartment. This condition

is sometimes referred to as flashover. The above critical temperatures are based on observations during the course of these experiments

.

The fire buildup potential of a compartment can, therefore, be considered

as the highest value that the average upper air temperature might achieve

during the course of a fire.

The upper air temperature in a compartment of given size and enclosing

surfaces of prescribed physical and thermal properties can be estimated by means of an overall energy balance for the enclosed space. This treatment is

only concerned with the growth of the fire up to the time of flashover. The

compartment is assumed to be divided into two temperature regions with the

higher air temperature, Tg , in the upper part of the compartment and the ambient air temperature, Tq, in the lower part of the compartment. Furthermore

there is a continuous inflow of cool air through a single open doorway into

the lower portion of the compartment and gaseous combustion products exhausting from the upper part of the doorway. There is no other opening (door or window) . Under quasi-steady-state conditions the heat balance equation for

the compartment can be written as Rate of

heat

generated

Rate of

heat + convected

through

the

opening

Rate of

heat + absorbed

by and

conducted

through

the interior

surfaces

Rate of

heat

radiated

through

the

opening

(3-1)

9
If the mass flow rate of the exhaust gas is assumed to be that of the

incoming air and that its heat capacity is the same as that of air at the same temperature, the heat convected through the doorway may be expressed as DCV (Tg - Tq) , where D is the density of the ambient air; C is the average

heat capacity of air between the temperatures To and Tg,- and V is the volumetric flow rate of the incoming air which may be supplied by the ventilation

system or be induced by the fire. The error due to these assumptions decreases

as the volumetric airflow rate increases for a given total rate of heat generation in the compartment. While the heat transferred to the hot upper sur- faces depends on a temperature difference between the gas and the surface, it

is assumed that this difference is small and that the upper surfaces are approximately at the temperature Tg . The heat conducted through the lining

materials in the upper part of the compartment is proportional to the temperature difference across their thickness, which is approximately equal to

(Tg - Tq) . It is assumed that the unexposed surface is at the ambient temperature, Tq. The net heat loss by radiation from the upper surfaces and the

hot gas layer is proportional to

(T - T "+) or (T 2 + T 2) (T + T ) (T - T )

* g o g o g o g o

where the air and surface temperatures in the lower part of the compartment are taken to be at the ambient temperature, Tq. The radiation transferred into the

lower part of the compartment either passes out the doorway or is absorbed in

lining materials. The temperature-rise of these lining materials in the lower

region of the compartment is assumed to be small prior to flashover so that

their temperature is taken to be Tq. The total heat losses within the compartment and by radiation through the doorway are given, approximately, by L Au

(Tg - Tq) where Au is the total area of the hot upper surfaces and L is the

heat loss coefficient which depends on Tg and To.

The total rate of heat generation in the compartment is QB, the product

of the effective heat of combustion of the burning material and the mass burning rate, respectively. Here it is assumed that all of the combustion takes

place inside the compartment. With the above approximations, equation (3-1) can be written as

QB - DCV (Tgo- T ) + L A (T - T ) (3-2)

u g o

The loss factor, L, can be represented by a sum of terms,

L = + + Lj^ (3-3)

where L-p corresponds to the initially high rate of transient heat conduction

into the surface, L^^ accounts for the steady-state heat conduction, and Lr

is due to radiation losses which usually dominate at the temperatures corresponding to flashover. Since this model is not concerned with the time of fire

buildup but its maximum extent, Lrp will be neglected. The steady-state con- duction coefficient is given by

^c = I

where K is the thermal conductivity of the lining material and X is its thick- ness. The radiation coefficient is given by

10
= tea (Tg'* - T^'+)/(Tg - T^) = feo (Tg2 + t^2) + (3.5)

where e is the effective emittance of the radiation source which will in general include both gas and solid surfaces, o is the Stefan Boltzmann constant,

and f is the ratio of the effective radiating area to the area of the heated

surface, A^, in the upper part of the room. If the radiation is from the

gas layer or if the upper surfaces were black the effective radiating surface

would be equal to the area of the overhead which is the same as the floor

area. A, so that f = A/A^. If the radiation were all from the upper surfaces

and none of it were absorbed in other regions of the upper surface, the effective radiating area would be A^^ so that f = 1.

Equation (3-2) can be rearranged to give the temperature rise:

_ ^ QB/(DCV) (3_gj

^ 1+LA /(DCV)

u

Equation (3-6) can be expanded to yield

(B/B ) (QB /DC V) (C /C)

(T - T ) = 2 5 2 2 . (3-7)

^ ° 1+(C /C) (L/DC ) (A /A)/(V/A)

where Bg is the stochiometric burning rate (i.e. the burning rate of the fuel

requires to consume all of the oxygen entering the compartment) , Cq is the

heat capacity of the air at ambient temperature, and A is the floor area. Equation (3-7) contains some important groupings as illustrated in equation

(3-8) :

Y0* (C^/C)

(T - T ) =• : (3-8)

^ ° l+(CyC) (L/DC^) (AyA)/(V/A)

where B/B^ is identified as the fraction of the oxygen depleted from the incoming air and is denoted by Y, and the quantity (QB^/DC^V) is a characteristic

temperature rise, O*. Y has a maximum value of unity and can be measured

during the course of the room fire tests.

The ratio of the heated area to the floor area, A^/A, will vary with the room configuration, and the location and severity of the fire. For a 3.1 x 3.1 X 2.4 m (10 x 10 x 8 ft) high compartment with the heated air layer

extending down to one-half of the ceiling height, it would be 2.6. For larger

compartments of the same height it will be less than this. (A^/A) has been

observed to vary during the course of a fire.

V/A is a ventilation parameter equal to the volumetric inflow divided by

the floor area. For forced air ventilation this would be specified by the

designer. For open doorways it would be proportional to the wh^^^ factor,

where w and h are the width and height of the doorway, respectively. For

fully developed compartment fires the inflow would be about 45 wh3/2 ft^/min

if w and h are in feet and approximately 25 wh3/2 m^/min if w and h are in

meters [11]. In developing fires, the inflow would be less than this value.

11
The calculation of the characteristic temperature rise, G*, is based on

the combustion of cellulose. However, the value of 0* should be relatively

independent of the material used for its determination. The following values

were used for its calculation:

Q = 1.53 X 10'+ J/g (6.6 x 10^ Btu/lb) [net heat of combustion]

D = 1.32 X 10"^ g/cm3 (0.08 Ib/ft^),

= 1.01

^

(0.24 Btu/lb/°F)

and

Bg/V = 2.31 X

10""* g/cm3 (1.44 x lO"^ Ib/ft^)

The burning rate per unit volume of air consumed, Bs/V, is based on the

following data. The molecular weight of cellulose is 162. There are 6 moles

of oxygen consumed per mole of cellulose burned. The oxygen fraction of

normal air is assumed to be 0.208 and the volume of one mole of air at ambient

temperatures is 0.86 ft^. This results in a characteristic temperature-rise

of 2,650 °C (4800 °F) . C/Cq is 1.035 at the 700 °C (1,292 °F) temperature

assumed for flashover. Substituting the calculated values of 0* and C/Cq

for air into equation (3-8) , the temperature-rise for the freely burning fire

in a compartment will be given approximately by

2560 Y

(T^ - T ) = -. (3-9)

^ 1 + 725 L (A^/A)/(V/A)

Equation (3-9) separates the expression for temperature into convenient factors which can be measured individually during the compartment fire tests.

Y is measured as the oxygen depletion fraction and can be expressed as

Y = I

= ^

J. = Eq, (A,/A) (3-10)

S DC V 0* DC 0*(V/A) i o o

The summation which includes all of the combustibles involved in the fire,

focuses down on the fire test requirements. The per unit area heat release

rate, qi, must be obtained with a heat release rate calorimeter, and the area

involved in the fire, A-j^, requires information from some kind of flame spread

test. Both qi and A^ depend on the radiation field and this should be reflected

in the test methods. Whether there is an i-th term depends on the ignitability

of the material which is related to the ease-of -ignition test.

Note that in a ventilation limited fire Y approaches unity and the fire

buildup potential, Tg-Tg, is determined by the denominator of equation (3-9)

.

As will be seen later this condition was present in the compartment fire test

with the door closed.

This expression also displays some scaling requirements. The ratio of

the involved area to the floor area, Ai/A, should be preserved. This requires

geometrical scaling since the i-th combustible may be a wall or a ceiling.

12
However, (V/A) must also be preserved so one must make adjustments of the

dimensions of the openings to secure the proper airflow.

A correlation can also be derived for relating the oxygen depletion and

temperature of the air in the upper part of the compartment. The derivation

assumes that all losses are by radiation into the lower part of the compartment. It further assumes that the product fA^/A is equal to unity. Then from

equations (3-5) and (3-8) the theoretical relationship between Y and (Tg-To)

/

can be written for any ventilation parameter V/A as

(T - T

g

DC (T - T ) g o

(T - T ) / (-)

^ g o ^a' (3-11)

For purposes of calculation, the following numerical values are recom- mended :

0*

C_

2,640 °C,

J = 1. 01 g°C (0. 24 Btu/lb/°F)

;

= 1.01 + 10 J

g°C '((Tg - T^)/2)

^1 or 0. 24 1 1 + 0.56. 5 X lO"** 10 (Tg-T^)/2^ (T,

e = 0.8,

= 298 K (537 °R)

,

Btu/lb/°F,

D =

3 3 3 1.32 X lO" g/cm (0.08 lb/ft )

3.2. Modeling Principles and Preliminary Studies

Reduced scale modeling methods are available for simulating the fire

buildup in compartments [12,13]. One of these used at the Illinois Institute

of Technology Research Institute (IITRI) [12] , requires a constant ratio of

heat release rate to the volumetric rate of air inflow in order to maintain

the same temperature in the room. Their method can be stated briefly as follows

L ~ W scale

LH 3'^ ~ (scale)

2

Air Inflow ~ wh ^ ' ^ ~ (scale)

Fuel Input ~ (scale)

13
where L is the room length, W is the room width, H is the room height, v; is

the window width and h is the window height. These rules lead to the requirement that the fuel input from a combustible wall is proportional to l.H^^'^,

rather than to LH as it needs to be.

Factory Mutual Research Corporation (FMRC) approached the scaling problem

from dimensional analysis considerations [13] . Their findings indicate that

the temperatures and gas compositions in a room scale reasonably well for geometrically similar enclosures where the heat release rates are proportional to

the 5/2 power of the scale factor. This method places the ceiling of the

model and prototype at homologous points of the convection column generated by

the flame. However, since LH is proportional to the square of the scale

factor for geometrical scaling, this leads to a fuel input requirement from a combustible wall that is proportional to (LH)^/'*.

Neither scaling approaches can handle the contribution of combustible

walls, ceilings or floors. When such interior coverings are fully involved

with flames, their rates of heat release are proportional to the scale factor

squared. In order to evaluate the seriousness of this problem, quarter-scale

model runs of several full size fire tests of combustible paneling materials

using the IITRI method were performed. Their scaling requirement exaggerated

the doorway and ceiling heights and resulted in 59% more paneling surface than

necessary to produce the proper fuel contribution necessary to maintain the

same fuel to air ratio. The prototypes for this modeling were the corner

fire tests run inside of the burnout room for HUD [2] . In those full size

experiments 1. 2x2. 4m (4x8 ft) panels of the specimen material formed one corner in the rear of the room. The ceiling above the corner was lined with

another 1.2 x 2.4 m (4 x 8 ft) panel of gypsum board. The fire exposure

source was a 6.4 kg (14 lb) wood crib placed in the corner. The model fire

exposure source was a gas burner consisting of a steel box with a mineral wool

cover to even out the flow. The gas flow was adjusted to produce one-sixteenth

of the heat release rate of the wood crib based on a value of 15.1 x 10^ J/g

(6,500 Btu/lb) for wood. The area of the top surface of the burner was one-sixteenth of that of the wood crib so that the fuel flow rates per unit area were the same. Comparison of the model and full-scale results showed

fair agreement prior to active fire involvement of the wall. Once the wall

was burning well, air temperatures in the upper part of the room were about

70% higher in the model burn [14].

Next a model having geometrically scaled room dimensions was evaluated

[10] . The same ratio of heat release rate to the volumetric rate of air inflow

as in the full size corner test was retained to secure the same temperatures

in the model. The wall above the doorway height traps the hot combustion

products from the fire and is critical to the phenomena taking place in the room so that this height was also scaled geometrically. The air inflow which

scales as wh3/2 ^as controlled by changing the width of the doorway in the

small enclosure. These scaling rules are summarized as follows:

1. All dimensions are proportional to the scale factor except for:

a. the width of the doorway which is proportional to the

square root of the scale factor and

b. the thickness of the materials which remains the same.

2. Fuel content and fuel surface area are proportional to the

floor area.

3. Air supply rate is proportional to the floor area.

14
The thickness should remain the same in order to maintain the same surface

temperature for a given incident heat flux. However, this heat flux will be

somewhat lower in the model because the reduced velocity will result in a smaller heat transfer coefficient. Although the times at which a particular

surface temperature is reached will be increased to some extent by this

reduction in heat transfer, the times in the model will still be similar to

those in the full-scale test. Adjustments in the thickness to account for

differences in the heat transfer coefficient are not practical particularly

for composite materials. Therefore the same thickness is used even though

some error in time will result. At earlier times when flame spread is significant, the same rate of flame spread as in the prototype would mean a relatively faster and more intense fire involvement in the small enclosure. For

rapid fire spread upward, this time difference for maximum fire involvement

may not be large, e.g., figure 3. However, for situations where much of the

fire spread is along the horizontal plane, the peak fire development could

occur much sooner in the model than in the prototype compartment. Figure 3 shows a comparison of the time histories of the air temperatures at 2.5 cm (1

inch) from the ceiling and at the mid-height of the compartment for full-scale

and model corner experiments with Lauan walls and gypsum board ceiling.

Figure 4 shows the inflow velocity profile at the doorway for enclosures

having both gypsum board walls and ceiling. The maximum inflow air velocity,

which occurs near the bottom of the doorway, should be proportional to the

square root of the height of the doorway. So the full-scale velocities have

to be divided by two for the comparison with the model. These similarities

between the model and prototype tests suggested the potential usefulness of

this scaling technique, which was adopted for the remainder of the modeling

work

.

4. RESULTS AND DISCUSSION

Preliminary experiments were performed with the quarter-scale enclosure

to arrive at a suitable set of full-scale test arrangements which were then

tested along with their reduced scale counterparts. Results from these com- partment fire experiments are discussed in this section.

4.1. Preliminary Experiments with the Model

Exploratory tests were conducted in the model enclosure with a scaled

down three-man bunk in simulated sleeping quarters to check on the effect of

ignition methods, arrangement of the bedding, bunk location and openness, overhead coverings, ventilation, and rate of heat release on the fire development

as well as to check on the performance of the instrumentation.

The findings indicated that variations in any one or combination of these

parameters could lead to one of three typical situations. Fire involvement in

the enclosure could be slight, moderate or extensive, and these conditions

correspond to a slight temperature-rise of the air in the upper part of the

compartment (less than 200 °C (392 °F) ) , temperatures in the vicinity of 250 °C

(482 °F) , or temperatures above 500 °C (932 °F) , respectively.

4.1.1. Ignition Method

Two modes of fire initiation in the berths were considered. In one case

a match flame was used to ignite a cotton sheet that was part of the bedding.

The other method was the ignition of 50 ml of ethyl alcohol, poured in the

middle of the bottom bunk. The latter method was found to assure a sustained

ignition and a more repeatable localized involvement of the bedding and was used for the full-scale test arrangements and their model counterparts. In

the full-scale test 800 ml of the alcohol was employed.

15
4.1.2. Arrangement of Bedding

When the bedding on the berths was well made the pillow and wool blanket

were the principal fuels exposed. These items were difficult to ignite and

sustain a fire. Bedding in considerable disarray with much of the cotton

sheets exposed resulted in a low level fire involvement. Kindling fuel, such

as a crumpled-up sheet placed on the bedding to simulate pajamas or other

clothes did not significantly increase fire activity in well made bedding, but

did lead to heavy involvement in the bedding in considerable disorder. Two

crumpled-up sheets led to somewhat higher compartment air temperatures . Additional kindling had no further effect. From this study it was decided to use

two extra bed sheets as kindling in each of the full size bunks.

4.1.3. Mattress Thickness

Although the modeling rules require that the thickness of materials re- main the same, the maintenance of adequate ventilation in the spacing between

the tiers of the bunk necessitated some reduction in the thickness of the

mattress used in the model. The 7.6 cm (3 in) thick neoprene mattress could

barely be squeezed along with the other bedding into the space between the

tiers of the model bunk. Little fire involvement of the bedding occurred

because of the insufficient airflow to the fire. Even berthing fires with

5.1 cm (2 in) mattresses appeared under-ventilated compared to fires using a 2.5 cm (1 in) mattress. To evaluate the adequacy of using the latter a burn

test with a three-tier bunk outfitted with 1-inch thick mattresses was conducted in the open alongside a full size three-man bunk in the NBS fire facility.

The degree of fire involvement appeared similar up to 10 or 12 minutes, at which

time a reduced level of fire activity was observed for the small model bunks

due to a heavy depletion of the fuel. All of the model Navy compartment fires

discussed in this report had bunks with the 2.5 cm (1 in) mattresses unless

stated otherwise.

4.1.4. Bunk Placement and Openness

The location of the bunk relative to the doorway can sometimes affect the

severity of the fire in the compartment. No difference was observed for the

bunk on the left side or rear of the compartment with a half open doorway (see

fig. 1). Both positions allowed sufficient ventilation, leading to moderate

fire involvement in the bunk. However, only a low level fire was found for

the bunk on the right side. The air inflow to the compartment had a less

direct path to the fire because the right half of the doorway was closed.

Consequently, the fire development was less severe in that situation. For a fully opened doorway the fire buildup was independent of the wall location of

the bunk

.

Openness of the bunk was also important to the fire development. Normally

the bunks were closed by aluminum panels at the back and at both ends. When

the back panel was removed from the bunk, the fire intensity increased.

Further enhancement of the fire occurred when both end panels were also taken

off. On the other hand when the front of the bunk was partially closed up

with privciCy curtains and the back and end panels were in place the intensity

of the fire was markedly increased. The former effect was due to increased

ventilation while the latter was due to increased heat trapping.

4.1.5. Room Ventilation

The effect of room ventilation on the enclosure temperatures depended

not only on its degree but also on its distribution. The fires were more severe when the forced air was delivered at each bunk than when the same amount of air

16
was delivered at the ceiling. Tests showed that a reduced doorway opening and

the absence of forced ceiling ventilation could result in an increased fire

intensity. Once the air supply is sufficient for complete combustion, the

effect of additional air is to reduce the air temperature in the compartment

by dilution.

4.1.6. Thermal Inertia of Overhead Linings

The effect of the thermal inertia of overhead linings on the fire behavior

in the compartment was also investigated. The rate of temperature-rise of a surface exposed to thermal radiation depends on its "thermal inertia," the

product of thermal conductivity, density and heat capacity or kpc. If the

quantity kpc is low the surface temperature rises rapidly and radiation feedback increases the heat release rate of the burning contents. This enhancement

may be enough to induce flashover when it might not otherwise occur. Three

materials, fibrous glass, high density acoustical paneling and asbestos insulation board, having kpc values of 58, 445 and 1276 min/m'+/°c2 (0.03, 0.23

and 0.66 Btu^/hr/f t'*/°F2 ) , respectively, were used for the overhead of the

enclosure. Results of the model tests with these materials are shown on table

3. The percent difference between the overhead temperature and the upper air

temperature 2 . 5 cm (1 in) from the overhead should decrease with decreasing

Kpc. However the results presented in table 3 indicated that surface emissivity or other presently unexplainable factors may sometimes override the

effect of thermal inertia.

4.1.7. Rate of Fuel Supply

In order to determine the air temperature rise of the compartment as a function of the heat supplied, experiments were conducted with a fully open

doorway and a gas diffusion burner on the center of the deck. Gypsum board

was used to line the bulkheads and overhead of the enclosure. The deck con- sisted of a piece of asbestos insulation board. Methane was metered to the

burner and the model compartment was allowed to reach equilibrium conditions.

The rate of methane flow was gradually increased for each run until newsprint

samples at various positions on the deck ignited. These ignitions were taken

to indicate the onset of flashover. Ignition times for these newspaper speci- mens varied from 5 to 7-1/2 minutes for a gas rate of 42 kW (40 Btu/s) or a scaled-up rate of 670 kW (630 Btu/s) for the full-scale compartment.

4.2. Model and Full-Scale Compartment Fires

Table 1 shows the range of conditions covered by the 13 full size and ten

model tests. Runs 1 to 4B were similar except for differences in ventilation

in the compartment and to the bunks. The following three tests, runs 5 to 7

,

involved variations in the interior coverings of the compartment. Subsequent

tests considered reduced but adequate ventilation to the bunks along with

three kinds of carpeting with pads. Visual observations taken during all of

the full size compartment fires are included in the appendix. Summaries of

the experimental results are indicated on tables 4 and 5. The data on air

temperature inside the compartment, the air temperature at the top of the doorway, the overhead temperature, the incident radiant flux on the deck, the weight

loss rate, the airflow, and the oxygen, carbon monoxide, and carbon dioxide

are tabulated on tables 4a and 5a at the times of the peak upper air temperatures and at the occurrence of flashover. Each test may have successive maxima in temperatures over the duration of the test, and these are included.

Shown in tables 4b and 5b are maximum values and corresponding times of the

overhead and doorway temperatures, the oxygen depletion and the concentrations

of CO and CO2.

17
(1) d) Q) Ui &>

(0 0) nj 0) (0 (U u U U i-l ^ M Vl M >-l H 3 0) -H 3 d) -H 3 > < 4-) > < 4-1 > < -P

(0 < (0 r< 03 << (0 a) 1 U U U U 1 U U 1 4-1 Q) (\> 4J <U 0) 1 4-1 Cl> 0 0 Ou d, w a a u) cu a,

Highe

*-M Pi D (U CH Highe Up Tem

Highe Up Tem

—

ng iH 4-1 •H cn C > <u c LD r- ID ID ri e Sh •H 1 1 1 I 1 1) +J c

00 in ro 1 c -H i 1 ea M 1

x:u TJ CO

(D Q) fO <u 1 > u 0) o c

1)

C -H

0) <: ^-1 3

+j ^ (0 IT)

C 1 (1) s > ,—1 CO

M-l +J q; o (1) ^-1 •H m aT3 e m Q t—

c d)

(0 Eh •HQ

(D (C3 QJ

CL) T) 4-1 f^ C 0 0 c > 4J ld ^•O 1 r- n\M O 05 (J ro

rn "ST"

U 0 ,—1

ro lo 0 OJ Cn a

(0 e

CO Sh (U +J r \ \J Eh m >

0)

rH (U

Q)

u

T! Q) 0) 0 -p a +j S 3c D M

y-i •H Q) o (—) o 0 s (1) a 0 <N lO LO

CO 0 (0 (1) 4J S-i iH Eh >

CO

H< a

to •H CM -pu

Q) \U C

iH

H o \ n ro

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22
4.2.1. Discussion of Individual Tests

A temperature history of the upper air, as determined by a thermocouple

one inch down from the center of the overhead, the overhead temperature directly

above the air temperature measurement thermocouple, the average temperature

of the upper surfaces (see fig. 1) , and the temperature of the exhaust flow

out of the compartment are presented for each test on figures 5 to 17. These

temperature histories, which indicate the degree of involvement, provide a framework for discussing the individual tests.

4.2.1.1. Tests Ml to M4B and 1 to 4B

The first two model compartment fire tests. Ml and M2 , had no openings

except for a7. 6x7. 6 cm (3x3 in) exhaust vent at the top of the closed

door. There was no forced ventilation in the first test. In the second test

there was 4.5 m^/min (160 ft^/min) of air delivered at the overhead vent near

the rear of the compartment. Neither test led to air temperatures above 200

°C (392 °F) , as seen in figures 5 and 6. In tests M3A and M3B with the door

open, figures 7 and 8, the upper air temperatures were more a function of the

forced air distribution in the room than of the increased convection from the

doorway. When this forced air was mainly introduced through the ceiling

vent, the highest air temperature attained was 202 °C (396 °F) . Diverting

this ventilation to the outlets on the bunks, as was the case in run M3A,

resulted in peak air temperature approaching 500 °C (932 °C) . This temperature would probably have been maintained for awhile or even increased if the

full mattress thickness could have been used. Except for a localized bunk

fire this was still not very spectacular. In all but test M4B, the bunk had

closed ends and back. In that test the back and ends were removed allowing

easy flow of air across the bunk. As had been observed from the preliminary

experiments, bunk openness was quite important to the degree of fire development. Figure 10 indicates that the air temperatures in test M4B reached a peak of 660 °C (1,220 °F) , and a short time later the locker material ignited

leading to room flashover.

Figures 5 to 10 also show the corresponding tests in the full-scale compartment. In test 1 there may have been sufficient air leakage into the

closed compartment to raise the temperature above that found in the counterpart model test Ml. More important is that the first two tests again exhibited

low intensity fires with temperatures less than 200 °C (392 °F) . As in the

corresponding model test, run 3B also had a peak air temperature in the

vicinity of 200 °C (392 °F) . Test 3A barely went over 500 °C (932 °F) but it

maintained the high temperature long enough to ignite the locker material in

the upper part of the compartment, causing a very severe localized fire. On

the other hand, runs 4A and 4B reached temperatures of 490 °C (914 °F) and

570 °C (1,058 °F) , respectively, but not flashover conditions as in their

model counterpart. Test 4A was conducted on a warm moist day. Run 4B was a repeat of 4A except it was performed under a lower humidity condition.

Qualitatively, one might say that the model did not scale well for tests 3A,

4A and 4B. There were large fires in M4B and 3A but not in the corresponding

tests 4A or 4B and M3A. However, the temperatures in all of these tests

approached or exceeded 500 °C (932 °F) which is a danger point. In one case,

the model enclosure became more involved; in another case it was the full

size compartment that had the most severe fire. It could have been deduced

from tests M3A and M4B that the potential for flashover was there. This is

all that the model is required to do.

4.2.1.2. Tests M5 to M7 and 5 to 7

Runs 5, 6 and 7, figures 11 to 13, were similar to test 3B except for

variations of the interior coverings. The high density acoustical panel which

had a high thermal inertia was used in run 5. Theoretically, this should

23
result in a steeper temperature gradient in the hot air adjacent to the ceiling. Data from tables 4 and 5 for tests 3B and 5 and their corresponding

model tests show that this temperature gradient in runs M5 and 5 is at least

twice that found in runs MSB and 3B. However, the ceiling temperature may not

be any lower, due to variations in the fire behavior between tests, e.g., the

ceiling temperature in M5 is higher than that in run M3B.

Melamine coated aluminum wall paneling was used in runs M6 and 6. The

surface coating was somewhat different from the vinyl coverings used in runs MSB and SB. However, the fire buildup in these situations did not adequately

involve the wall linings to show differences in flammability of the two

materials. As a result the peak air temperatures were expected to be and were similar to these observed for tests MSB and SB.

In runs M7 and 7 a pad was used under the carpet. This had the effect of

reducing heat losses to the floor. This can be critical for fire involvement

of the floor covering near flashover conditions. However, at much lower temperatures this reduction of floor losses is minimal. Air temperatures were

somewhat higher than those in runs MSb and Sb, but these differences could

well have been within the experimental variation expected between tests of

the same arrangement.

In tests 5, 6 and 7 and their model counterparts the changes in the

interior linings were not major ones, and the fire growth and resulting peak

air temperatures were similar to those observed for run 3b. This indicates

fairly good reproducibility of the fire buildup in the compartment fire

tests. Secondly, the peak temperatures in the model tests were close to the

values of 200 to 244 °C (392 to 471 °F) observed in the full size fires.

4.2.1.3. Test M8, M9 and 8 to 11

The remaining four full size tests were used to check out a room arrangement which preliminary experiments indicated could lead to a more severe fire

development. Forced ventilation to the room was curtailed and the doorway

opening was closed halfway for these tests. Jute-hair underlayment was also

used in conjunction with carpeting to minimize heat losses to the metal deck.

The chronology of each fire, as indicated by the upper air and surface

temperatures, is shown on figures 14 to 17. Run 8 experienced peak temperatures in the neighborhood of 350 °C (662 °F) , between the low level fire

range of 200 to 250 °C (392 to 482 °F) and the 500 °C (932 °F) area where

pyrolysis of combustibles such as clothes in the locker can occur and further

buildup to flashover becomes more of a possibility. Model test M8 , on the

other hand, reached 706 °C (1,303 °F) . The carpet blackened and the newspaper

on the floor discolored. One contributing factor to this difference in fire

behavior between the model and prototype fires could be due to the non- scaling of flame spread. As mentioned in section 3.2, the same rate of flame

spread as in the full size compartment would result in a relatively earlier

and more intense fire involvement of the fuel in the model. Figure 14 shows

the temperature history of both tests 8 and M8. In the early stage of the

fire development, the light combustible materials such as the sheets and

blankets were the principal fuel involved. At about 5 and 12 minutes in the

model and prototype, respectively, the temperatures began to increase again.

This later stage of fire involvement included the mattress and the pillows.

A faster involvement of the bedding at this point could have meant the difference between an accelerated growth leading to a potential flashover and a low

intensity fire.

The following test, run 9, was similar to run 8 and was designed to

yield information on the fire performance of three bunk privacy curtain

materials, the effect of a partial confinement of the incipient fire and the

effect of a more rapid involvement of the bedding on the lowest bunk. The

24
curtains were positioned in front of each tier of the 3-man bunk and consisted of two high temperature polyamide cloths of different weights placed

side by side alongside another piece of 50% polyamide — 50% phenol formaldehyde material. The alcohol used previously to initiate the fire was spread

along the length of the bottom bunk rather than localized on the bedding as

in the preceding tests. This method of ignition was also necessary to assure uniform exposures for all three materials making up the curtains. Roughly

one-quarter of the bunk opening was left to allow for ventilation of the

fire.

Early in run 9, it was apparent that the curtains were confining the

fire to the bunk of fire origin. Fire quickly enveloped the overhanging

sheets from the upper berths as in all of the previous tests, but would not

involve the sheets on the top of each bunk. Once the overhanging portions of

the sheets burned away, the fire extinguished itself on the top and middle

tiers and was then confined to the lowest berth. All this occurred within

the first two minutes. In all of the preceding tests, except the first two

having the closed doorway, the fires involved the sheets which simulated

clothes on the upper bunks. The polyamide curtains also burned off within

the first two minutes, while the polyamide-phenol formaldehyde material

remained almost to the end of the test. Confinement of the fire resulted in

very dense smoke out of the doorway. This smoke, in the opinions of the

observers, was more dense than in any of the previous tests. After 7-1/2

minutes the fire penetrated the aliaminum panel supporting the mattress on the

second bunk and quickly involved the bedding. The fire continued to preheat

the uppermost bunk, until at about 17 minutes, when the fire burned through

the aluminum panel to involve the fuel on the top bunk. Five minutes later

the entire combustible contents of the compartment was aflame.

The fire scenario was somewhat similar in the model test M9 . Unfortunately

the thin mattress used to achieve the proper ventilation to the bedding led to

a depletion of fuel after 17 minutes. Nevertheless the upper air temperature

reached a peak of 531 °C (988 °F) by that time and indicated a potential flashover condition.

Run 10 was similar to run 9 except only 50% polyamide-50% phenol formaldehyde material was used for the privacy curtains, and acrylic carpeting was used on the deck. This test demonstrated how easily deck coverings with high

flame spread ratings can contribute to the complete fire involvement of a compartment. The fire scenario was very similar to that of run 9 with the

fires extinguishing in the upper bunks after the first couple of minutes. At

about the same time, a piece of burning material from the bedding ignited the

carpeting. Within 10 minutes the compartment was a hot inferno. Much of the

curtains lasted over this time duration.

In run 9, most of the curtains were burned off by two minutes. Much of

the curtains endured the entire fire exposure in test 10, but the effect of a longer duration partial confinement of the bunk fire was masked by the fire

involvement of the deck covering. Run 11 was performed to evaluate this parameter. Localized ignition was reverted to for comparison of results between

tests having the same ignition pattern. A carpet with thermal properties similar to wool, but having a lower flammability rating was chosen to assure that

no ignition of the deck material would occur until at or near flashover. The

initial fire buildup was similar to those in runs 9 and 10. After 7-1/2

minutes the compartment was filled with very heavy smoke and flames could only

be observed along the bottom bunk. Then at about ten minutes, flames shot

out of the doorway and the carpet ignited. The compartment cleared somewhat,

and it became obvious that the upper berths had been involved in fire for some

time. The longer confinement of the bunk fire had evidently resulted in a more

rapid fire buildup in the compartment.

25
Intuitively one would have expected a longer time to flashover for run

11 than that for run 10 because of the additional heat release from the deck

covering in the latter test. However smoke from the burning carpet stratified in a low dense layer, blocking off radiation from the hot upper surfaces

of the compartment to the unignited portions of the deck. Other experimental

evidence [14] shows that fires having short flames, such as those observed on

the carpeting, result in a thicker thermal layer in the compartment and not

in a concentrated layer near the overhead. Thus, much of the heat generated

from the burning carpet in run 10 flowed out of the compartment at an elevation far from the overhead. Consequently, the compartment temperature in run

10 was only somewhat higher than that in run 11, but because of the smoke

stratification in the former case, radiation to the deck was probably similar

in both runs. This would account for the similar times to flashover for the

two tests.

4.2.2. Supporting Measurements

In addition to the temperatures in the upper part of the compartment

which indicated the degree of fire buildup, a number of diagnostic measurements was made to help understand the phenomena taking place. These included

the vertical temperature profile at the center of the compartment, the con- centration of oxygen, carbon monoxide, and carbon dioxide at the top of the

doorway, smoke obscuration in the compartment, rate of air inflow, and the

thermal radiation at the deck level.

4.2.2.1. Thermal Radiation

Values of the radiation flux to the deck have been plotted as a function

of upper air temperature, figure 18. The limited data available from the

full size fires compared reasonably well with the small scale values. This

correlation is similar to one for overhead temperatures. However the advantages of relating flux to upper air temperatures are that the latter is a reliable measure of fire buildup in a compartment, is independent of the

physical properties of the overhead material and can more easily be treated

analytically. Calculations show that if the overhead or adjacent hot air

layer is the principal radiating source, the view factor between it and the

deck below lies between 0.24 and 0.36 over most of the deck area. This is

in agreement with the averaged value of 0.31 found for the data plotted on figure 18, assuming an emissivity of unity for the radiating source. A solid

line representing the case where both the view factor and emissivity of the

radiating source are unity is superimposed on the figure.

In actuality radiation to the deck results from both the hot gases and

the upper surfaces. From figure 18 a view factor higher than 0.31/e fits

the lower values of the radiative flux, while a value less than 0.31/e

correlates the higher fluxes.

The higher view factor at the lower fluxes can possibly be explained in

the following way. It is known that low intensity fires and short flames

lead to a thicker and lower thermal layer in the compartment [14] . This

results ii. a lowering of the radiating surfaces and hence to effectively

higher view factors. A severe localized fire would produce flames much

taller than the compartment but here such flames are deflected horizontally

beneath the ceiling and lengthen further because of the lower rate of entrainment between the heavy air and the light hot flame gas stream. This results

in high temperatures and intense radiation from the air in the upper part of

the compartment. This also results in a vertical constriction of the zone of

hot gases flowing across the overhead toward the exit. A consequence of this

is lower view factors.

26
It is evident from figure 18, that rather limited data was available for

the correlation. In most of the full size and several quarter-scale tests,

the radiometer was either not working properly, or was not calibrated correctly. For tests 9 and 11, it was necessary to assume that the radiant flux

to the deck was 2 W/cm^ (1.8 Btu/s/ft^) at the time of flashover in order to

retrieve the data at earlier times. This is a reasonable assumption [2,14].

4.2.2.2. Temperature Distribution in Compartment

Comparison of localized overhead and upper air temperatures for the two

scale fires have already been made. To obtain a more complete understanding

of modeling enclosure fires on a reduced scale as well as a better general

understanding of compartment fires, temperature distributions in the compartment were examined. Figures 19 and 20 show vertical distributions of temperatures from the overhead down to the deck for two representative fire situations.

Due to non-scaling of fire spread, a topic discussed earlier, times can

not be easily scaled for a phenomena as complex as a fire in a furnished com- partment. Temperature profiles from the model runs should be compared with

the prototype fires at comparable stages of the fire development. It can be

argued that the successive peaks in upper air temperatures define these stages

of the fire buildup. However, it is sometimes difficult to compare results,

e.g., where the model test has three peaks and the prototype only two maxima.

Therefore temperature profiles at times corresponding to all peak upper air

temperatures have been presented for these two tests. It is important to

keep in mind that the principal objective is to determine whether a potential

exists for flashover. In an earlier discussion, a temperature in the vicinity

of 500 °C (932 °F) was selected as a lower limit for this flashover potential.

Thus only the highest peak temperature during a test is of major concern. What these vertical distributions of temperatures should show is whether

there is a similarity of these profiles between the model and prototype fires.

From the figures given one can conclude that such similarities exist.

Analysis of the data also discloses a thicker thermal layer in compartments having reduced openings, test 1, 2, 9, 10 and 11. Results also indicate

that the vertical temperature profile in the model follows the prototype

temperature distribution as long as the upper air temperatures did not greatly

exceed 500 °C (932 °F)

.

Horizontal temperature variations along the overhead surface were monitored only in the full size fires. Overhead temperatures were highest over

the fire source and along the path of the hot gas flow exhausting towards the

doorway. Surface temperatures decreased rapidly away from these localized

areas of intense heating. The averaged upper surface temperature histories

for all thirteen tests are shown on figures 5 to 17. Data taken at six over- head and three bulkhead positions four inches down from the ceiling were used

in these averages. Superimposed on each of these figures are the air temperature measurements taken at 2.5 cm (1 inch) from the ceiling, the temperature

of the ceiling directly above it, and the thermocouple reading at the doorway. Analysis of the data indicated that the single best measurement used to

approximate the averaged upper surface temperature would be the air temperature near the top of the doorway.

4.2.2.3. Compartment Ventilation

As mentioned in section 3.1., the upper limit for the volumetric air

inflow through the doorway would be 45 wh^^^ ft^/min if the width w and the

height h are in feet and 25 wh^^^ m^/min if the dimensions are in meters.

This value is achieved only under fully developed and ventilation controlled

fires. No airflow measurements were taken under flashover conditions in the

compartment fire tests. Consequently, all of the recorded volumetric inflows

27
were expected to be less than this value. In many of the full size and

quarter-scale enclosure fires, there was forced ventilation in addition to

the fire induced inflow of air through the doorway. For the full size tests,

this total ventilation varied from 13 to 22 wh^/^ m^/min (24 to 40 wh3/2

ft^/min). The total volumetric air to the reduced-scale model fires ranged

from 9 to 19 wh3/2 mVmin (16 to 35 wh3/2 ftVmin) .

4.2.2.4. Oxygen Depletion and Carbon Monoxide

Air temperatures and oxygen depletion were the highest in runs 9 and 11

and so were the air temperatures in run 10. The oxygen sampling line was clogged in the latter test and the data could not be taken. Figures 21 and

22 show the temperature rise versus oxygen depletion for tests 9 and 11, re- spectively. The concentration of oxygen in these tests is shown at 2 minute

intervals and at flashover. A similar plot is also presented on figure 23

for all of the quarter-scale and full size fire tests. However only the data

corresponding to peak upper air temperatures are indicated. Where there were

two or more successive peaks for any single run, the oxygen depletion values

for all of the temperature maxima were indicated. The open data points denote

model data and the solid data points denote full-scale data.

Equation 3-11 was used to relate the oxygen depletion and temperature of

the air at the top of the doorway and was superimposed on all three figures.

The equation demonstrates the effect of the thermal losses. The solid line

on figures 21, 22 and 23 is the theoretical curve assuming no heat losses

while the dashed lines are the theoretical curves taking radiative heat

losses into account with certain assumptions. It assumes that all losses are

by radiation into the lower part of the compartment. This latter assumption

is not unreasonable at temperatures above 400 °C (752 °F) . At these higher

temperatures radiation is the dominant mode of thermal losses from the upper

surfaces. At lower temperatures conduction losses to these surfaces cannot

be ignored. Two typical ventilation parameters of 1.8 and 5.1 cm/s (3.5 and

10 ft/min) were considered for the partially and fully opened door situations.

As is evident from the figures, the correlations between the temperature rise

of the doorway air and the oxygen depletion were reasonably good.

Carbon monoxide and oxygen depletion values corresponding to temperature

maxima from all of the quarter-scale and full— scale tests were plotted together

on figure 24. CO concentrations varied linearly with oxygen depletion down

to an O2 concentration of about 7% at the doorway. At lower O2 concentrations,

the levels of CO increased sharply.

4.2.2.5. Smoke Optical Density

Production and spread of smoke are especially hazardous in confined

spaces such as the quarters on board ship. Smoke impairment of vision can seriously impede the safe escape of occupants and reduces the effectiveness

of the crew fighting the fire.

The smoke obscuration reading on the vertical smoke meter inside the

compartme. t could be used to approximate visibility for the space. If the

smoke is assumed to be evenly distributed over the upper half or 1.07 m (3.5

ft) of the compartment then the visibility is independent of the path orientation through the smoke. Gross, et al. [9] defined a critical smoke optical

density of 0.26 per meter (0.08 per foot) or 16% light transmission as the

upper limit of visibility of objects due to smoke obscuration over a 3.05 m

(10 ft) viewing distance. This is roughly equivalent to a 47% smoke obscuration reading across the vertical smoke meter. Percentage obscuration in the

compartment is plotted against time on figure 25 for all thirteen full size

fire tests. Selected representative data from each run are shown. The

numbers on the figure correspond to their respective compartment fire tests.

28
On the average, smoke production from fires with peak upper air temperatures

at or over 500 °C (932 °F) exceeded this visibility limit after 1-1/4 minutes.

In the compartment fires where the maximum air temperatures were kept below

500 °C (932 °F) , the average time to achieve this obscuration level was roughly 2-3/4 minutes.

Light transmission data recorded near the top of the doorway also substantiates this anticipated trend of higher obscuration in the compartment

due to an increased combustion of the bedding. Smoke obscuration values at

both interior and doorway locations are also given on table 4a at times of

peak upper air temperatures.

4.2.3. Heat Balance for Compartment

While there is a considerable net radiation exchange between the upper

and lower regions of the compartment, ultimately the heat production from a fire is dissipated to its surroundings by convection and radiation losses

through the doorway and conduction through the compartment surfaces. The

relative magnitudes of these losses depend on the ventilation to the space.

A well ventilated area will lose more heat to the hot flow exhausting from

the compartment than one having a slow rate of air change in the room. This

fact is well illustrated by the approximate thermal losses calculated during

the relatively steady burning periods in runs 3B and 9, which had a fully

opened and half opened doorway, respectively. The time intervals taken for

these calculations were between 3 and 9 minutes in run 3B and between 6 and

18 minutes for run 9. Table 6 summarizes these findings.

Table 6. Heat Losses from Compartment

Mode of Energy Transfer

Test 3B

Opened Doorway

(percent loss)

Test 9

1/2 Opened Doorway

(percent loss)

Convection out doorway 71 40

Radiation out doorway 3 4 Conduction through vinyl coated

bulkhead

15 37

Conduction through fibrous glass

insulated bulkhead

2 3

Conduction through fibrous glass

suspended ceiling

2 2

Conduction through deck covering 7 14

29
Analysis of these results showed that the energy convected out the

doorway accounted for a larger percentage of the total energy dissipated from

the compartment in run 3B than in test 9. The restricted inflow of air in

the latter case also resulted in higher room temperatures and hence increased

conductive losses through the interior linings and more energy radiated to

the deck covering and out the compartment opening. The convective losses of

71 and 40% for runs 3B and 9, respectively, agree with the results from gas

burner fires in a somewhat similar room configuration lined with one inch

thick asbestos insulation board [14]. Those experiments indicated that

approximately 56% of the energy generated by the fire escapes the enclosure

in the form of a hot outflow through the doorway.

Complete accounting of heat generation within the enclosure and thermal

losses from the compartment interior were complicated by incomplete combustion

of the burning materials and by the limited instrumentation of the test com- partment. In run 3B the bedding was the only material burning. Calculations

showed that only about 68% of the weight loss monitored over the period of

steady burning experienced complete combustion. The remainder of the fuel

left the compartment as unburned combustible gases and dense grey black

smoke. Weight loss data from test 9 was not available.

'5. LABORATORY FIRE TEST DATA

All materials considered or used in the compartment fires series were

evaluated with the five laboratory fire tests. Table 7 summarizes the results

from the ASTM E-162 (radiant panel) , potential heat, smoke density chamber,

heat release rate calorimeter and ease-of-ignition tests.

The radiant panel data are presented in terms of the flame-spread factor,

Fg, as well as the flame-spread index, Ist which is the product of Fg and

the heat evolution term. These quantities have been described in section

2.3. The factor Fg has been included as it is a direct measure of the rate

of flame propagation and is not biased by the rate of heat generation of the

material. The latter property is measured with the heat release rate calorimeter. Currently materials are being screened by the flame-spread index IgUsually materials evolving little heat also exhibit low rates of flame spread.

Analysis of the data in table 7 and data on some materials used in home

building [2], table 8, indicates that a Fg of under 5 corresponds to an Ig

value of 25 or less.

Materials submitted as part of the Navy's habitability program and which

had Ig values of 25 or lower performed well in the compartment fires. None

of these interior linings became significantly involved until near flashover

conditions were attained.

Materials were tested separately and in the composite actual use configuration. The substrate material of a specimen can noticeably affect both the

the flame-spread factor and index for the specimen. Inspection of the data

for the polyamide carpet indicated that Ig decreases by an order of magnitude

when 0.64 cm (1/4 inch) steel is substituted for the 1.27 cm (1/2 inch)

asbestos- -oment board used on the standard tests. A two to three fold difference was also noted in the F values.

s Sometimes test behavior of composite specimens can obscure the performance of the substrate material. A sample of neoprene mattress material with

ticking, cover, and a single sheet over its surface had a flame—spread index

of 226. The same neoprene specimen by itself had an index of only 4. Whereas the surface layers burn away quickly and frequently contribute mainly to

the initial phase of the fire growth, heat release from the neoprene substrate

is slow and sustained over a relatively long time and can ultimately lead to
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32
flashover conditions. To assure proper interpretation of test data, it is

recommended that materials be tested individually and in actual use configurations . The potential heat of the compartment materials having an organic base

varied within the range of 16,300 to 23,200 J/g (7,000 to 10,000 Btu/lb)

.

Mineral base and fibrous glass materials such as high and low density acoustical overhead paneling and low density bulkhead sheathing are naturally

expected to have low values. Coatings and thin laminates contribute relatively little potential heat to the compartment even though the potential

energy per gram of material is high.

Measurements in the smoke density chamber include the peak specific

optical density for both flaming and smoldering exposures and determinations

of the potentially hazardous gases NO + NO2 , S02f HCN, CO and HCl.

The rate of energy released from a material depends on its fire exposure.

For this program, material specimens were subjected to a constant moderate

irradiance level of 6 W/cm^ (5.3 Btu/s/ft^). Both the maximum one minute

average rate of heat release per unit surface area and the total heat generation per unit area for each material are also included in table 7.

Results of the ease-of-ignition test are presented in terms of the time

for the exposure flame to ignite the specimen surface. Ignition is taken to

be the persistence of flames for one second or longer on the specimen following

the curtailment of the exposure flame.

6. DESIGN GUIDELINES

6.1. General

'n this study of compartment fires the overhead and bulkhead linings and

two of the deck coverings were limited by the Navy to several candidate materials for shipboard application. The interior finish was restricted to two

overhead materials, three bulkhead sheathings and four deck coverings. With

the exception of the latter, these materials also had a fairly narrow range of

flame spread and smoke generation potential. For the deck coverings the variability in these fire properties was less limited. However, the deck material

usually does not become involved in the fire until flashover conditions are imminent or has occurred. Consequently, relationships between laboratory fire

test performance of materials and their behavior in actual compartment fires were difficult to establish. Nevertheless, there is sufficient state-of-theart information available together with the observed fire behavior of materials

on which to draw some conclusions and to improve present rules for fire safe

material usage.

The design criteria suggested in this section for the lining materials

for the crews berthing compartment are based on the following laboratory fire

tests: the radiant panel (E-162) , the potential heat method, the heat release

rate calorimeter, the ease-of-ignition test and the smoke density chamber.

In choosing the highest acceptable level for the outputs of each of these

tests, the following points were taken into account:

(1) The tests performed to date provide no justification for relaxing

the requirements on flame spread, potential heat, and smoke density from

those recommended earlier in phase 1 of this project [3].

(2) The lining materials, used in the compartment fire tests, met the

phase 1 requirements and did not provide a large increase in the fire hazard

beyond that provided by the bedding itself. Therefore, any new criteria presented here should not rule out the use of these materials which have been

successfully employed in the full-scale compartment tests.

33
(3) While the phase 1 criteria were adequate in choosing the safe materials used in the present tests, demonstrations [15] of rapid fire buildup in rooms lined with low density foam plastics have indicated that flame spread

ratings alone may not be capable of ruling out all potentially hazardous lining

materials. Therefore it is suggested that any lining -material to be used must

also satisfy certain heat release rate and ignitability requirements. These

requirements can be set on a more rational basis taking heat balances and fire

buildup times into account.

The criteria presented here represent the state-of-the-art, and the on- going analysis of compartment fire buildup is aimed at their improvement.

6.2. Flame Spread and Rate of Heat Release

No reason was found to alter the flame spread requirement of equal to or less than 25 for the overhead and bulkhead materials. The measurement, however, must be made on the material in the same thickness and backed in the same manner as it would be installed. The effect of backing material is dramatically illustrated for carpets in table 7. Although the same flame spread

requirement can be given for the deck coverings, more suitable alternative

acceptance criteria may be based on the material's ability to sustain flame

propagation under the thermal radiation levels anticipated on the deck surface.

The flooring radiant panel test [7] described in section 2.3.2. measures this

critical radiant flux for sustained horizontal flame spread along the surface

of a material. This test is expected to replace the ASTM E-162 method for

measuring the flammability hazard of deck coverings. As indicated on table 4,

the upper air temperature due to fires in full size compartments, having closed

bunks without privacy curtains and with typical ventilation at each berth, does

not exceed 400 °C. Even if temperatures were as high as 450 °C the irradiance

on the deck would only be about 0.5 W/cm^. Thus, deck coverings having a critical flux equal to or higher than this value would not be expected to contribute significantly to the fire.

The preliminary experiments with the quarter-scale model indicated that

a total heat release rate of approximately 670 kW (630 Btu/s) would be required

to produce an upper air temperature of 700 °C (1,292 °F) which is necessary

for full involvement ofa3x3x2.1m (10x10x7 ft) compartment having an opened doorway. In most situations this temperature must be maintained for a duration on the order of a minute in order for the irradiance from the heated

upper surfaces to ignite the combustible contents in the lower part of the

compartment

.

This heat generation rate is equivalent to 72 kW/m^ (6.3 Btu/s/ft^) of

deck area. Evidence from the full size corner fire experiments [2] supports

this finding. It was found in those tests that just 3 m^ (32 ft^) of wall

paneling having a maximum one minute average heat release rate of 200 kW/m^

(17.7 Btu/s/ft^) , as measured in the heat release rate calorimeter with an exposure level of 6 W/cm^ (5.3 Btu/s/ft^), together with a fire source (6.4 kg or 14 pound wood crib) can flashover a room having 9.3 m^ (100 ft^) of deck

space. The ceiling material was gypsum board whose paper surface burned away

in the early part of the test, and thus contributed little to the overall heat

release at the time of flashover.

A simple calculation based on the above number indicates that the maximum

rate of heat generated by the paneling would be 600 kW (570 Btu/s) in addition

to the 180 kW (170 Btu/s) from the burning crib. In actuality the entire burning surface was not releasing heat at the maximum one minute averaged value,

and a somewhat lower rate occurred. This calculation is essentially in agreement with the above finding from the model experiments.

34
In order to effectively apply this critical rate of heat generation to

the Navy berthing quarters, an estimate must first be made of the potential

thermal contribution from the furnishings. Then the balance of the energy

production needed to attain the critical air temperature in the compartment

could establish the limits for the rate of heat generation from the interior

finish

.

The burning rate of the bedding in test 4B with the opened bunks reached

a maximum of 41.6 g/s (0.092 Ib/s) . The median value of the potential heat

of the bedding materials is seen from table 7 to be about 19.7 kJ/g (8,500

Btu/lb) . Then a maximum heat release rate of 820 kW (780 Btu/s) could occur

if there were complete combustion of the materials. This was enough to exceed

the critical temperature for flashover without any contribution from the

locker or the material lining of the compartment.

However, for the closed bunks with no privacy curtains or abnormally high

airflow rate at the bunks, the maximum burning rate recorded was only 15.1 g/s

(0.033 Ib/s) or 300 kW (280 Btu/s) . This would allow a total heat release

rate of 370 kW (350 Btu/s) from the lining materials before full involvement

could be reached. The criteria for the heat release rate of the lining

materials could be based on the concept of keeping their total heat production

rate below 370 kW (350 Btu/s).

Since the carpet did not contribute any heat until full involvement

occurred in the compartment fire tests, only the bulkhead and the overhead

will be considered in the heat contribution calculation.

Hence the requirement for no flashover could be stated:

A„ q_ + A q < 37 0 kW (350 Btu/s)

a D o o —

or ^

qg + q^ ^ 4 W/cm2 (3.5 Btu/s/ft^) (7-1)

where qg and q^ are the heat release rates per unit area of the bulkhead and

overhead surfaces, respectively. Ag and A^ are the areas of the bulkhead and

overhead, respectively, that could potentially be contributing heat prior to

flashover. In a compartment fire this could include the entire overhead and

the upper half of the bulkhead surface. Extensive fire spread along the bulkhead in the lower part of the compartment is much less likely to occur than

that along the bulkhead surface exposed to the hot air layer in the upper part

of the compartment. Experimentally, little fire involvement of the upper bulkhead surface was observed in the compartment fires until flashover conditions

were approached. In those tests in which there were closed bunks and no privacy curtains or unusual ventilation conditions there was no flashover of

the compartment or flame spread down the bulkheads. tsTiile flame spread across

the ceiling is relatively easy, even for low flame spread materials, downward

flame spread is not likely to occur for these materials until the high radiation levels characteristic of flashover are approached. Hence, the requirement of I3 <_ 25 should be sufficient to eliminate the first term of equation

(7-1) . Hence the area of potential involvement could be considered to be the

overhead which must have a heat release rate of less than 4.0 W/cm^ (3.5

Btu/s/ft^). The overhead materials used in these tests will pass this criteria.

35
The bulkhead lining materials can be given a greater margin of safety by

requiring them to have heat release rates <_ 6 W/cm^ (5.3 Btu/s/ft^). This

additional requirement would pass the bulkhead lining materials which performed satisfactorily in the compartment fire tests while ruling out materials

having high heat release rates. It would also help eliminate marginal materials such as the coated fiber acoustical tile shown on table 8. This material

did not have a high maximum one minute average rate of heat release per unit

surface area. However a significant rate is maintained over a sufficiently

long period, as evidenced by its relatively high effective heat of combustion,

Q, to result in an additional increase in air temperature of about 200 °C over

that from the burning crib in the compartment.

The above recommended limits on the heat release rate from materials is

based on the maximum one minute average rate of heat release per unit surface

area as measured in the heat release rate calorimeter [5] under an irradiance

level of 6 W/cm^ (5.3 Btu/s/ft^).

6.3. Potential Heat

In addition to the necessity for limiting the rate of heat production and

thus the intensity of the fire, there is also a need for restricting the duration of the fire in the unlikely event that flashover did occur. The latter

requirement assures the structural integrity of the compartment components as well as reduces the probability of fire penetration into adjoining occupancies.

A commonly used relation between fire severity and fire load [16] shows that

for every 12.1 kg/m^ (2-1/2 Ib/ft^) in fire load, the fire severity, in terms

of ASTM E-119 type of fire exposure, increases by 1/4 hour. This represents

about 2.38 X 10^ J/m^ (21,000 Btu/ft^) of deck area. The typical contents in

shipboard berthing compartments would then lead to about 15 minutes of fire

exposure. The compartment fire tests have indicated the seriousness of such

exposures on 0.25 cm (0.10 inch) thick aluminum bunk partitions. There is

further experimental evidence [17] that exposure times as short as 6 minutes

could also be detrimental to 0.64 cm (1/4 inch) thick aluminum plating.

However it is recognized that realistic limits must be set to allow for a minimal of necessary furnishings and interior finish on board ship. For this

reason it is suggested that a practical limit of 1.1 x 10^ (1,000), 3.4 x 10^

(3, 000) and 5.6 x lO'^ J/m^ (5,000 Btu/ft^) be set for the overhead, bulkhead

and deck coverings, respectively. For a 3.1 x 3.1 m (10 x 10 ft) space having

a 2.1 m (7 ft) overhead, the compartment interior finish could then contribute

another 10 minutes of fire severity. These limits would also allow the use of

the materials which performed satisfactorily in the compartment fire tests.

6.4. Time to Ignition

Compartment fire tests with some low density foam materials [15] have

demonstrated that low flame spread ratings do not always assure low fire risk

performance in compartment type fires. These materials also exhibited ignition times of less than 60 seconds. Ignition is defined here as the persistence of flames for one second or longer any place on the specimen following

curtailment of the ignition source. Ignition time is the duration of flame

impingemen required to produce ignition. All of the overhead and bulkhead

finish materials used for the compartment fires shown on table 1, had ignition

times greater than 60 seconds and performed well in the compartment fires. In

order to eliminate those low thermal inertia materials which ignite quickly it

is suggested that ignition times greater than 60 seconds, as determined from

the ease-of-ignition test [4] , be set as the criterion for the ease-of -ignition

.

36
6.5. Smoke Production

Criteria for limiting the generation of smoke in the compartment is difficult to establish for interior finish and furnishings in the room. The

burning of a relatively small quantity of certain materials could produce

sufficient smoke to completely obscure visibility in the compartment, in

critical spaces such as passageways, and in neighboring spaces.

For instance, a burning rate of about 7.6 g/s (1 Ib/min) in the bedding

produced sufficient smoke to exceed the limit of visibility of objects within

1-1/2 minutes in compartment test 3A, which had a fully opened doorway.

The smoke meter in the test compartment monitored the rate of smoke production as it mixed with the volumetric air inflow to the space. The smoke

density chamber, on the other hand, measured the total smoke produced in a fixed enclosure volume. Ideally the optical density per meter of viewing distance through the smoke, OD/m, should be the same for both situations when the

ratio of the burning rate to the inflow to the compartment, , is the same as the ratio of the specimen weight loss to the enclosure volume, R_, in the

~ 5 smoke density chamber. The quantity Rg was 1.4 x 10 g/cm^ (0.00085 Ib/ft^)

for the mattress material tested in the smoke density chamber and corresponded

to an OD/m of 4.3.

For compartment fires having a fully opened doorway, the burning rate and

volumetric air inflow were available for tests 3A, 3B, 4A, 4B and 7, Two of

these runs, tests 3A and 4B, attained this OD/m value of 4.3 over the 2.1m (7

ft) viewing distance in the smoke meter inside the compartment within 3 minutes as shown on figure 25. The averaged rates of weight loss and air inflow

were 19.7 g/s (2.6 Ib/min) and 32.8 m^/min (1,160 ft^/min) , respectively, over

this -^ime period for these two tests. This corresponded to a R^ ratio of 3.6

x 10 g/cm^ (0.00224 Ib/ft^) or 2.6 times greater than the Rg ratio used in

the smoke chamber to produce the same optical density per meter of viewing

distance. Runs 3B and 7 took much longer to achieve this value of OD/m, and

this smoke level was never reached in run 4A.

The differences between the smoke chamber readings and smoke levels in

the compartment tests were not surprising. In the smoke chamber, the material

was completely burned and the smoke is representative of the entire composite

specimen. In an actual fire the smoke concentration at any moment would be

dependent on the materials burning at the time. There could be as much as a 30% variation in the specific optical density, Dg, and consequently the same variation in the values of OD/m, resulting from the differences in the smoke

potential among the bedding component materials.

More important and larger variations between laboratory and actual smoke

concentrations could result from differences in the fire exposure, material

configuration, spatial distribution and coagulation of smoke particles in the

two cases

.

As mentioned earlier a burning rate of 7.6 g/s (1 Ib/min) could fully

obscure visibility in the compartment. It is then conceivable that under some fire conditions a typical rate of 15 to 23 g/s (2 to 3 Ib/min) over a 10-

minute burn duration could easily produce enough smoke to fully obscure vision,

e.g., over a 3-m (10-ft) viewing distance, in a space which is twenty or more

times larger than the compartment of fire origin, assuming uniform mixing of

the smoke, no deposition on surfaces, and an absence of coagulation of the

smoke particles.

37
Although such visibility limits are logical in terms of ease of egress

and more effective fire fighting capabilities, they are impractical and are difficult to apply in the real world. In spite of this there is still a need

to limit the smoke generation ability of materials as the duration and quantity

of smoke production determine its residence time and frequently its ultimate

spread through the ship.

The laboratory ratings of the materials considered under the Navy's habitability program and used in this study indicated that the phase I criteria

need little revision. As improved materials having lower smoke outputs become

available, it may be advisable to consider tightening the requirements for all

materials used in the berthing areas.

It is suggested that the smoke control requirements for interior finish

be as follows:

Location Maximum Optical Density, D for m Flaming and Non-flaming Exposures

Overhead £ 150

Bulkheads ± 150

Deck < 450

6.6. Toxicity of Combustion Products

In order to relate the measurements of combustion gases in the smoke density chamber to their potential concentrations in the compartment and neighboring spaces, the volume of the space accessible to the combustion products must

be known and certain assumptions must be adopted. The fire related gases are assumed to be uniformly distributed throughout the compartment and connecting

areas. Then if the gas concentrations were to vary directly with the ratio of

the surface area of the burning material to the accessible shipboard space, some estimate may be made of the immediate environment on board ship.

The most potentially hazardous environment will occur where there is full

involvement of the entire compartment. When this happens, even bulkhead materials having a flame spread of 25 or less and deck linings contribute to the

spread of potentially hazardous combustion products throughout neighboring shipboard spaces. The concentrations of fire associated gases will be estimated

for this situation. The gas concentrations from the smoke density chamber were

based on a sample area to chamber volume ratio of 0.0083 m~ (0.0025 ft~M.

If, e.g., we have a 283 m^ (10,000 ft^) space, the equivalent burning surface

area would be 2.3 m^ (25 ft^) to maintain this area to volume ratio found in

the smoke density chamber. Table 9 outlines the estimated potential gas con- centrations for this example along with the toxicological information [18,19]

for the various combustion products analyzed.

All of the above by-products of combustion exceeded their life safety

range for 2 to 5 minute exposures. The neoprene mattress alone accounted for

most of the oxides of nitrogen, almost all of the HCl and a good proportion of

the CO. . other major producer of the latter was the vinyl laminate. Even

without the contribution from the mattress, the combustion products from the

remaining materials would have exceeded the lethal range for all of the gases.

The gas concentrations presented in table 9 are only for one fire condition where a dilution factor of fifteen occurs and uniform mixing with the sur- rounding air is assiamed. It doesn't necessarily represent a typical situation

on board ship. Without further fire tests on board ship or in simulated shipboard spaces, the movement, stratification and hence dilution of combustion

products in adjacent corridor and compartment spaces are difficult to ascertain.

Without this further information criteria for limiting the potentially toxic

products of combustion cannot be presented at this time.

38
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6.7. Summary of Criteria

The criteria recommended for the lining materials in the crews berthing

compartment are given in table 10. They are based on the five laboratoryscale fire tests discussed in this report, namely the E-162 radiant panel, the

potential heat test, the NBS smoke density chamber, the NBS heat release rate

calorimeter, and the ease-of-ignition test. These criteria represent the

state-of-the-art and have been formulated from a restricted range of lining

materials. Additional research is required to examine their range of applicability.

7. CONCLUSIONS

The air temperature in the upper part of the compartment is a good

measure of its fire buildup. At 500 °C (932 °F) , there is rapid pyrolysis and

ignition of most combustible materials in the upper portion of the room. When

the air temperature near the ceiling reaches 700 °C (1,290 °F) ignition of

light combustibles can occur in the lower part of the compartment due to

thermal radiation. In general the rate of heat production needed to attain

such temperatures is dependent on the size of the enclosed space, the degree

and distribution of the ventilation, the location of heat sources, and the

thermal properties of the interior finishings. For a3x3x2.1m (10 x 10 x

7 ft) compartment having a fully open doorway, a heat generation rate of

roughly 72 kW/m^ (6.3 Btu/s/ft^) of deck area is necessary to achieve the

highest of these temperatures.

Fires in the bedding on the currently used berthing units having opened

sides have been found to exceed this critical rate of heat production. However, the burning of the bedding in the redesigned units resulted in less

intense fires. These berthing units had partitions along three sides and were

proposed under the Navy's habitability program for making shipboard spaces

more liveable for the crew. Fires in these newer bunks could still contribute

45% of the critical rate of heat release, but allowed some leeway for additional interior finish and other contents.

The full-scale and quarter-scale fire experiments have helped establish

the ability of the laboratory fire tests to provide interim acceptance limits

for fire-safe selection of materials aboard ship. Comparison of the fire

experiments have also indicated that fire testing in a quarter-scale enclosure

is a useful tool for investigating fire performance in full size compartments.

Observations and analysis of these fires along with an analytical treatment of

fire buildup in an enclosed space have resulted in an improved interpretation

of fire test ratings. As a result, more rational criteria for minimum fire

risk material usage have been formulated for interior finish and furnishings

in Navy berthing quarters. These design rules have been summarized in section

6.7 of this report (see table 10).

40
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41
8 . REFERENCES

[1] Fire Performance Requirements and Approved Specifications for Interior

Finish Materials and Furnishings (Naval Shipboard Use) , Military

Standard 1623 (SHIPS) (Sept. 10, 1973).

[2] Fang, J. B. , Fire Buildup in a Room and the Role of Interior Finish

Materials, Nat. Bur. Stand. (U.S.), Technical Note 879 (June 1975).

[3] Benjamin, I. and Gross, D. , Naval Shipboard Fire Risk Criteria, Final

Report Phase 1 - Evaluation of Fire Test Requirements, NBS Report 10159

(Jan. 26, 1970)

.

[4] Parker, W. J., The Development of a Test for Ease of Ignition by

Flame Impingement, NBS Report 10495 (Feb. 11, 1972).

[5] Parker, W. J., Development of a Heat Release Rate Calorimeter at NBS,

NBS report 10462 (Mar. 14, 1972).

[6] Robertson, A. F. , Gross, D. and Lof tus , J. J. , A Method for Measuring

Surface Flammability of Materials Using a Radiant Energy Source,

Proceedings of the American Society for Testing Materials, Vol. 56,

1437-1452 (1956).

[7] Hartzell, L. G. , Development of a Radiant Panel Test for Flooring

Materials, Nat. Bur. Stand. (U.S.), NBSIR 74-495 (May 1974).

[8] Loftus, J. J., Gross, D. and Robertson, A. F., Potential Heat - A

Method for Measuring the Heat Release of Materials in Building Fires,

Proceedings of the American Society for Testing Materials, Vol. 61,

1336-1348 (1961)

.

[9] Gross, D. , Loftus, J. J. and Robertson, A. F. , Method for Measuring

Smoke from Burning Materials, American Society for Testing Materials,

Philadelphia, Pennsylvania, ASTM Special Technical Publication No. 422,

164-204 (1967).

[10] Parker, W. J. and Lee, B. T. , A Small-Scale Enclosure for Characterizing the Fire Buildup Potential of a Room, Conference Proceedings on Experimental Methods in Fire Research, Standard Research Institute,

Menlo Park, California, held May 9-10, 1974.

[11] Thomas, P. H. , Heselden, A. J. M. and Law M. , Fully-Developed Compartment Fires-Two Kinds of Behavior, Fire Research Technical Paper No. 18,

Fire Research Station, Boreham Wood (Oct. 1967)

.

[12] Waterman, T. E. , Determination of Fire Conditions Supporting Room

Flashover, Final Report IITRI Project M6131, DASA Contract No. DA-49

146-x Z-475 (Sept. 1966).

[13] Heskestad, G. , Modeling of Enclosure Fires, Fourteenth Symposium

(Ini ;jLnational) on Combustion, The Combustion Institute, 1021-1030

(1972).

[14] Parker, W. J. and Lee, B. T. , Fire Build-up in Reduced Size Enclosures,

Fire Safety Research, Proceedings of a Symposium held at the National

Bureau of Standards, Gaithersburg , Md., Aug. 22, 1973, Nat. Bur. Stand.

(U.S.), SP-411 (Nov. 1974).

[15] Castino, G. T. , et al., Flammability Studies of Cellular Plastics and

Other Building Materials Used for Interior Finish, Underwriters

Laboratories Inc. (1975).

42
[16] Building Materials and Structures, NBS Report BMS92 (Oct. 7, 1942).

[17] Lee, B. T. , Fire Performance Testing of Bulkhead Insulation Systems for

High Strength to Weight Ship Structures, Nat. Bur. Stand. (U.S.),

NBSIR 76-1012, Final Report (1976).

[18] Gross, D., Loftus, J. J., Lee, T. G. and Gray, V. E., Smoke and Gases

Produced by Burning Aircraft Interior Materials, Nat. Bur. Stand. (U.S.),

Building Science Series 18 (Feb. 1969)

.

[19] Driesbach, R. H. , Handbook of Poisoning, Fifth Edition, Lange Medical

Publications, Los Altos, California (1966).

[20] Parker, W. J., Comparison of the Fire Performance of Neoprene and Flame

Retardant Polyurethane Mattresses, Nat. Bur. Stand. (U.S.), NBSIR 73-177

(Apr. 1973)

.

43
LOCKER

18,19

•8

12 13 • • 4

•

214

• • •lO

IS • 6

5,7, 20,21

9,16

BUNK

VIEW

PORT

SLIDING

DOOR

<

UJ3

flO

UJ

BACK BULKHEAD

18, 19

I II

•3

6 12

10

4,13 14 17

• 6

5,7, 20,21

9,16 I

O

<

UJX

-ICDX

o

Bulkheads on Front

and Left Sides

1 inch fibrous

glass attached

to 0.75 inch

thick asbestos

insulation board

walls

Bulkheads on Back

and Right Sides

1/16 inch

aluminum paneling

separated from

0.75 inch thick

asbestos insulation board walls

with 2x4 inch

steel studs

Station Instrument

1 Load Cell

2 Radiometer on deck

3,4 Flashover indicator (newsprint) on deck

5 Velocity measurement near botton of doorway

6 Vertical smoke meter

7 Horizontal smoke meter at top of doorway

8 Gas sampling at elevation of lowest berth

9 Gas sampling near top of doorway

10 Vertical strand of 11 thermocouples extending from

ceiling to underneath carpet

11 to 15 Ceiling thermocouples

16 Thermocouple near top of doorway

17 - Thermocouple on right side of specimen wall

surface 4 inches from ceiling

18 Thermocouple on back side of specimen wall

surface 4 inches from ceiling

19 Thermocouple on asbestos insulation board surface

across from thermocouple 18

20 Thermocouple on front surface of fibrous glass

4 inches from ceiling (above door)

21 Thermocouple on back surface of fibrous glass

behind thermocouple 20

Figure 1. Plan View of Two Compartment Arrangements Showing Locations

of Furnishings and Instrumentation.

44
45
AIR DIFFUSER

[-^27-3/4"—

H

SECTION A-A

0.10- inch ALUMINUM END PLATE

.10- inch ALUMINUM MATTRESS SUPPORT

inch ALUMINUM BACK PARTITION

FRONT VIEW

notes: (I) THREE EQUALLY SPACED 3-Inch ANGLE IRONS

USED UNDER EACH MATTRESS SUPPORT

PLATE

(2) EACH INDIVIDUAL DIFFUSER DESIGNED TO

VENT 8 CFM OF FRESH AIR

Figure 2b. Description and Dimensions of 3-Man Berthing Unit.

46
FULL-SCALE I 2.5 cm down from

l/4*SCALE i center of ceiling

FULL-SCALE ) midheight, center

l/4-SCALE i of room 800 —

600 —

P 400 —

<

a:0.

200

4 6 8

TIME (minutes)

Figure 3. Air Temperatures Inside Compartment - Lauan Walls,

Gypsum Board Ceiling.

47
THE VELOCITY DATA FOR THE FULLSCALE TEST IS SCALED DOWN BY THE

SQUARE ROOT OF THE RATIO OF THE

DOORWAY HEIGHTS.

A FULL-SCALE

A l/4-SCALE

±

10

±

12

J.

14 16

10 15 20 25 30

AIR INFLOW VELOCITY (cm/»)

35 40

Figure 4. Velocity Profiles in Doorway at 10 Minutes for Full- and Quarter- Scale Enclosures with Gypsum Board Linings.

48
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30 40

Figure 9. Temperatures in Upper Part of Compartment for Fire Test 4A.

53
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60
f€(T (T*- V) W/cm2

Figure 18. Thermal Radiation Incident on Deck as Function of

Upper Air Temperature.

61
62
63
900

800

0 0.10 0.20 0.30 0.40 050 0.60 0.70 080 090 1.00 OXYGEN DEPLETION FRACTION

Figure 21. Temperature Rise in Doorway Exhaust Versus

Oxygen Depletion for Test 9.

900r

SUBSCRIPT FOR EACH DATUM POINT

CORRESPONDS TO THE TIME IN MINUTES

800-

oo

OL I I I I \ I I I I I 0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 OXYGEN DEPLETION FRACTION

Figure 22. Temperature Rise in Doorway Exhaust Versus

Oxygen Depletion for Test 11.64
0 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 OXYGEN DEPLETION FRACTION

Figure 23. Temperature Rise in Doorway Exhaust Versus Oxygen Depletion

for all Tests Having Opened and Partially Opened Doorways.

lOOi0 2 4 6 8 10 PERCENT CARBON MONOXIDE

Figure 24. Oxygen Depletion Versus Carbon Monoxide Concentration in

Doorway Exhaust for the Compartment Fire Tests.
1

Figure 25. Smoke Obscuration in Full-Scale Compartment Fire Tests.

66
APPENDIX - TEST OBSERVATIONS

Test 1 - November 7, 197 3 Time

min; s Observations

1:00 Fire confined to bottom berth. No smoke observed through exhaust

port.

2:00 Fire still confined to lowest bunk. More smoke, but not heavy.

3:30 Flames appeared to have diminished.

5:50 Flames have spread along overhanging sheets to all three bunks.

7:00 Whitish more dense smoke coming out exhaust port.

8:15 Fire almost out inside compartment. Some flames near pillow areas,

20:00 Smoke has not abated. Flaming on uppermost bunk.

22:30 Flames out again.

39:00 Not much happening. Smoke has not diminished.

60:00 Test terminated.

Test 2 - November 14, 1973

Conditions prior to ignition 69 °F and 54% humidity

Time

min ; s Observations

2:00 Two-thirds of bottom berth in flames. Middle bunk about to ignite,

2:15 Middle bunk ignited. Smoke fills the entire exhaust port.

4:00 Unable to see flames inside. Whitish-grey smoke coming out from

sxhaust port.

8: CO Conditions unchanged.

10:^0 Bottom and middle berths aflame again.

14:00 No flames observed inside compartment.

15:3v. Smoke is dense and yellowish in color. 2-1/2% CO at doorway.

18:00 HCl concentration greater than 100 ppm in the exhaust port.

20:30 HCN concentration went off scale on colorimetric detector tube.

Concentration higher than 150 ppm.

40:00 Conditions unchanged inside compartment.

42:00 Test over.

67
Test 3A - November 21, 1973

Conditions prior to ignition - 64 °F and 60% humidity

Time

min:s Observations

0:30 One half of lowest berth is aflame. . oi f

1:00 Second bunk has ignited.

1:10 Third bunk has ignited. Large 3-ft diameter charred area on ceiling

directly over top bunk.

2:30 Hot outflow from compartment extends 45 to 50% of the way down from

top of doorway.

3:00 Top berth is flaming slightly. Middle bunk flaming somewhat more. Bottom bunk heavily involved in flames. White smoke, exiting from

compartment, fills upper 40% of doorway.

5-.'. • All three bunks heavily involved with flames.

7.1. Short bursts of flames observed out doorway.

':40 Flames no longer coming out of doorway.

8:00 Hea^'v grey smoke issuing from room, fills top third of doorway.

12:15 7\11 three bunks flaming. Aluminum plate used in supporting the

mattress on the top berth has melted. Crumpled newspaper used for

indicating the occurrence of flashover in the compartment hasn't

ignited.

13:00 Flames are half way down along the vinyl covered paneling.

14:00 Newspaper on the deck has ignited. Flaming material may have dropped

onto it.

17:00 Materials in upper part of locker have ignited.

19:00 Cotton items in lower half of locker now flaming.

22:00 80 - 90% of vinyl covered paneling has burned away.

25:00 Test terminated. ^. v . ; ' u>v Jjib- T. hixn

Post-fire '

• f.' Analysis Ceiling intact. Carpet unburned. Less than 50% of cotton waste and

clothes in locker burned. Aluminum plates used for supporting the

mattresses on the two highest bunks melted. Some melting also

occurred in the two aluminum end plates of the 3-man berthing unit.

68
Test 3B - December 27, 1973

Conditions prior to ignition - 65 °F and 56% humidity

Time

min ; s Observations

0:30 Lowest bunk is well af lamed.

1:10 Second berth has ignited.

1:30 Highest bunk has ignited.

1:50 Inflow air velocity at bottom of doorway is 110 fpm.

2:45 Doorway air velocity is now 140 fpm.

4:30 Air velocity at bottom of doorway has increased to 155 fpm.

5:00 Much of the lowest berth is burning. Mid-level berth has less fire

involvement. Only about 20% of uppermost bunk aflame.

5:30 Inflow velocity along bottom of doorway now is about 140 fpm.

7:25 Doorway air velocity is 120 fpm.

9:00 Smoke departing from compartment fills upper 40% of doorway opening.

11:30 Mid-level bunk is covered with small isolated flames. Fire in top

bunk is almost out. Intense glowing observed in part of the neoprene

mattress on the bottom berth.

16:00 Only isolated flames left along mid-level bunk. Fires are out on the other two berths.

16:25 Fire is out on all three berths.

21:00 Conditions unchanged. Test over.

Test 4A - December 5, 1973

Conditions prior to ignition - 70 °F and 71% humidity

Time

min : s Observations

2:30 Inflow air velocity near bottom of doorway is 150 to 200 fpm.

2:45 Mid-level bunk has ignited.

3:00 Uppermost berth has ignited.

3:25 From motion of the smoke in the compartment the neutral plane (hotcold flow interface) is at about half room height.

5:00 All three bunks burning evenly. Flames are reaching the ceiling.

5:30 Inflow velocity along bottom of doorway is 190 to 220 fpm.

5:45 Flames emerging from doorway.

6:10 Flames are no longer coming out of doorway.

69
7:25 All three berths still af lamed.

9:30 Lowest bunk still flaming. Upper two berths somewhat inactive.

10:30 Bottom and middle berths flaming slightly. Fire in uppermost bunk

is out.

13:00 Conditions unchanged. •' ' -

15:00 Isolated flames on middle bunk. Fires are out in the other berths.

17:00 Conditions unchanged.

20:00 Only smoldering remains in all three berths.

Test 4B - December 7, 1973

Conditions prior to ignition - 63 °F and 46% humidity

Time

min:s Observations

0:45 Middle berth has ignited.

1:00 Top bunk has ignited.

1:20 Air inflow velocity at bottom of doorway is 150 fpm.

1:35 Flames spreading across part of ceiling.

2:00 Ceiling has almost entirely blackened. Hot exhaust from compartment

fills upper half of doorway.

2:25 Velocity at doorway is 190 to 200 fpm.

5:00 All three bunks still aflame.

5:30 Velocity along bottom of doorway is now 180 fpm.

9:30 Fire on uppermost berth is out. Only isolated small flames left on

the middle and lowest bunks.

10:00 Doorway velocity is 150 fpm.

13:00 A few isolated flames on bottom berth. No flaming observed on upper

two bunks.

17:00 Newsprint on deck still has not ignited. Test terminated.

Post

Analysis Uppermost 3 0% of the vinyl laminate on the back bulkhead is charred.

1 j>p 20% of the vinyl on the right side bulkhead is also charred.

Contents on top shelf of locker has discolored.

70
Test 5 - December 5, 1973

Conditions prior to ignition - 55 °C and 44% humidity

Observations

Second bunk has ignited.

Third bunk has now ignited.

Smoke from compartment fills upper 40% of doorway.

All three bunks burning evenly.

Smoke exhausting from compartment now fills the top 25 to 33% of

doorway.

Air inflow velocity along bottom of doorway is 110 fpm.

Top and middle berths are still aflame. Bottom bunk is smoldering

All three berths are now smoldering. Smoke from compartment fills

upper one-third of doorway.

Conditions unchanged. Test over.

Test 6 - January 29, 1974

Conditions prior to ignition - 67 °F and 38% humidity

Observations

Second berth has ignited.

Third berth has ignited. Air inflow velocity along bottom of

doorway is 110 fpm.

Middle and bottom bunks burning well. Top berth flaming slightly.

Velocity at doorway is still 110 fpm.

Air velocity at doorway remains unchanged. Smoke from compartment

fills upper 40% of doorway.

All three bunks are still flaming.

Velocity along bottom of doorway is now 100 fpm.

Middle bunk burning vigorously. Pillows on top and middle berths

are burning well. Bottom berth has only small isolated flames.

Doorway air velocity is 110 fpm.

Only small flames observed on all three bunks.

Air velocity at doorway is 8 5 fpm.

Doorway inflow velocity is now 100 fpm. All three berths are now

smoldering.

Velocity at doorway is 90 fpm.

71
26:00 Test terminated.

Post fire

Analysis Newsprint on deck and carpet are unaffected. Contents of locker

have not discolored. Large sections of melamine laminate separated

from aluminum bulkhead.

Test 7 - February 7, 1974

Conditions prior to ignition - 56 °F and 42% humidity

Time

min:s Observations

3:00 Air inflow velocity at bottom of doorway is between 90 and 95 fpm.

4:00 Fire still confined to bottom berth.

5:10 Second berth ignited.

5:20 Third bunk has ignited.

7:00 Entire bottom berth aflame. About half of the lippermost and middle

bunks is flaming.

7:30 Pillow on top berth is now burning.

9:00 Air velocity along bottom of doorway is 100 fpm.

10:00 Bottom berth has only small flames. Flames in middle berth are now spreading to the pillow area. Uppermost bunk is burning well only

at the pillow area.

11:00 Pillow in middle bunk now burning vigorously.

12:00 Doorway air velocity is now 100 fpm. Only isolated small flames along

top and bottom berths. Middle bunk is flaming on pillow area. 19:00 Only a flickering of flames left on pillow area on mid-level bunk.

24:00 Newsprint indicator on deck has not ignited. Test terminated.

Post fire

Analysis Vinyl covered bulkhead unaffected except for the uppermost five

inches, which has an oily appearance. Some contents on top shelf

of locker has discolored slightly. Top thirds of fibrous glass

covered bulkhead also discolored somewhat.

, ' Test 8 - February 28, 1974

Conditions prior to ignition - 66 °F and 24% humidity

Time

min:s Observations

1:00 Half of lowest berth is aflame.

1:30 Air velocity at bottom of doorway is 100 fpm.

1:40 Second berth has ignited.

72
2:04 Third bunk has ignited.

2:30 Inflow air velocity at doorway is now 120 fpm.

3:00 All three bunks are burning well. Smoke fills upper 40% of doorway.

3:30 Inflow velocity is still 120 fpm.

4:00 Inflow air is mixed with a little of the smoke exhaust and conse- quently can be observed. The air enters at about half dooirway height

and dips quickly towards the deck.

5:30 Inflow is now 110 fpm.

6:30 Inflow along bottom of doorway is about 100 fpm.

7:30 All three berths are still burning. Velocity is now 120 fpm.

9:30 Air inflow velocity is 110 fpm. Only the pillow area along middle

bunk is flaming. The fires in the bottom and uppermost berths have

gone out.

14:00 Velocity along the bottom of the doorway is still 110 fpm. No flames

observed on all three bunks.

20:00 Test terminated.

Post fire

Analysis Upper one foot of the vinyl covered bulkhead surface appears oily

following the fire exposure. Only contents along the top shelf of

the locker has discolored.

Test 9 - March 7, 1974

Conditions prior to ignition - 74 °F and 58% humidity

Time

minrs Observations

0:20 Second berth has ignited.

0:34 Third berth has now ignited. Polyamide curtains aflame.

2:00 Flames extinguished in the two upper bunks. Flaming now confined

only to bottom berth.

2:45 Smoke fills the upper 40% of doorway.

3:45 Have extremely dense smoke, more dense than any of the previous tests,

Inflow of fresh air near the middle of the doorway is seen to dip

quickly towards the deck.

6:00 Flames are still confined to the lowest berth.

7:45 Second bunk is suddenly aflame. Fire appears to have penetrated

through the aluminum plate supporting the mattress.

12:00 Top berth still has no flaming. Middle and bottom berths only

flaming slightly.

18:00 Top bunk now heavily involved in flames.

73
21:00 Only the top bunk is actively involved in flames. The other berths

have little flaming and appear to be smoldering.

21:30 Flame front has spread one-quarter to one-third of the way down the

fibrous glass on the left bulkhead.

21:45 Carpet is aflame. Flashover of room contents. Fire extinguished

with water hose.

Post fire

Analysis Contents along whole length of locker was charred. Carpet was com- pletely blackened. Vinyl on right bulkhead was completely burned

away. Vinyl on back bulkhead burned off except along the lower

eight inches. Rupture lines were found along the exposed aluminum

bulkhead. Both of the bulkheads lined with fibrous glass were blackened over their entire lengths. Aluminum partition at pillow end

burned completely away. The partition at the foot end of the bunks was badly warped. The aluminum mattress support plates on the upper

two bunks had large gaping holes. Low density ceiling tiles above

the bunks were warped considerably and probably allowed the fire to

penetrate into the dead upper air space.

Test 10 - April 16, 1974

Conditions prior to test - 69 °F and 30% humidity

Time

minis Observations

0:30 Inflow air velocity at bottom of doorway is 35 fpm.

1:00 Cotton bed sheets draping over the sides of the upper two berths

have ignited. i . , 1:30 Inflow air velocity is now 95 fpm.

1:45 Fires are out along the upper two bunks. Inflow air velocity is

105 fpm. Carpet has just ignited from a piece of burning bedding

which had fallen on the deck.

3:00 Doorway air velocity is now 145 fpm. Smoke fills the upper 40% of

the doorway.

3:45 Doorway velocity has increased to 160 fpm. Upper two bunks are not

burning well.

7:00 Upper and middle berths still not burning well. Smoke from the

burning carpet is stratified in a low dense layer.

9:30 Smoke from the compartment has turned whitish in color. There is

active burning of all room contents.

14:00 All three bunks still burning.

18:00 Fire extinguished.

74"
Test 11 - May 3, 1974

Conditions prior to test - 74 °F and 61% humidity

Time

mints Observations

1:00 Cotton bed sheet hanging from middle berth has ignited.

1:10 Sheet hanging from top berth has ignited. Inflow air velocity at

bottom of doorway is 55 fpm.

2:00 Fire in uppermost berth is out. Flaming only near the curtain

opening on the middle bunk. Bottom bunk is still burning well.

Inflow air velocity is now 80 fpm.

2:30 Fires have extinguished in upper two bunks. Flames are still evident

along bottom berth. Inflow air velocity is 95 fpm.

3:30 Smoke fills the top half of the doorway. Inflow velocity is 90 fpm.

5:30 Smoke now fills the upper 55% of the doorway.

6:30 Air velocity at doorway has increased to 140 fpm.

7:00 Air velocity is now 125 fpm.

7:30 Fire still appears to be confined to lowest berth. Smoke exiting

compartment is extremely dense. Smoke is obscuring the fire development inside the compartment. Inflow air velocity has decreased to

100 fpm.

8:30 Still very smokey inside compartment. Inflow velocity is about

100 fpm.

9:30 Doorway air velocity is now 115 fpm.

10:15 Flames shooting out of doorway. Fire spreading along carpet area closest to bunk.

10:30 Remainder of carpet flashed over. Smoke level in the compartment

decreased markedly.

14:25 Fire dowsed with water from hose.

Post fire

Analysis Aluminum partition along the head end was completely gone. Gaping

holes were left on the partition at the foot end of the bunk. The

aluminum mattress support plates on the two upper berths either

melted or were burned away. Two rather large holes were found on the bulkheads lined with the vinyl coated aluminiim paneling.

75
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. public:ation or report no. NBSIR 76-1052

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Naval Shipboard Fire Risk Criteria - Berthing Compartment Fire Study and Fire Performance

Guidelines

5. Publication Date September, 1976

6. Performing Organization Code

7. AUTHOR(S)

D . i • TPP LicG and alia WW • JU • Parker r cLL tVCi. 8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 492 6387

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Ship Damage Prevention and Control

Navla Sea Systems Command

Dept. of the Navy

Washington, D.C. 20362

13. Type of Report & Period Covered

r max Jxeport

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less tactual sunmiary of most sigfiificant information. If document includes a significant

bibliography or literature survey, mention it here.) Judicious application of shipboard materials and choice of compartment furnishings

can significantly reduce the threat of serious fire on board ship. Unfortunately the

fire performance of materials is currently difficult to ascertain from laboratory fire

tests on the materials. Full size and quarter-scale compartment fires in conjunction

with an analytical treatment were performed to obtain an improved understanding of the

relationships between the laboratory fire test assessment and the observed behavior

of materials in actual fires. The compar-tment fire experiments indicated that the temperature of the hot air layer below the ceiling is a suitable quantitative measure of

the level of fire buildup in a compartment. When this temperature exceeds 700 °C

there is sufficient radiation from the hot air layer and the heated upper surfaces to cause ignition of all combustible materials in the compartment. For a3x3x2.1m

(10 X 10 X 7 ft) space lined with asbestos millboard having a 0.68 x 1.9 m (27 x 75 in)

open doorway a heat production rate of about 72 kW/m2 (6.3 Btu/s/ft2) of deck area is

enough to attain this condition. Fires in some bunk configurations alone could exceed

this critical rate of heat generation. Ventilation and its points of application were

found to be very important considerations. Observations of the fire scenarios in the

compartment tests along with an empirical and analytical analysis of fire growth in

compartment spaces have resulted in an improved application of the fire test ratings.

Consequently more rational design rules for fire safe material usage have been developed

taking into account the ignitability , flame spread, rate of heat release, potential

heat and smoke generation potential of materials. The. study also indicated the

practicality o^" using quarter-scale fire tests for studying f±te performance in full

size compartmeuts . KEY WORDS: Fire tests; flame spread; heat release rate; ignition; reduced scale models; room fires.

18. availability Unlimited

1

' For Official Distribution. Do Not Release to NTIS

1

' Order From Sup. of Doc, U.S. Government Printing Office Washington. D.C. 20402. SD Cat. No. C13

iCT^ Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

21. NO, OF PAGES

86

20. SECURITY CLASS

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22. Price

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