INST. OF

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CO Q* NBS SPECIAL PUBLICATION 639

U.S. DEPARTMENT OF COMMERCE/Nationai Bureau of Standards

Fire Research

and

Safety

100

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639

C.2
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act of Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology

and facilitate their effective application for public benefit. To this end, the Bureau conducts

research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is per- formed by the National Measurement Laboratory, the National Engineering Laboratory, and

the Institute for Computer Sciences and Technology.

THE NATIONAL MEASUREMENT LABORATORY provides the national system of

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Absolute Physical Quantities2 — Radiation Research — Chemical Physics —

Analytical Chemistry — Materials Science

THE NATIONAL ENGINEERING LABORATORY provides technology and technical ser- vices to the public and private sectors to address national needs and to solve national problems; conducts research in engineering and applied science in support of these efforts; builds and maintains competence in the necessary disciplines required to carry out this research and technical service; develops engineering data and measurement capabilities;

provides engineering measurement traceability services; develops test methods and proposes

engineering standards and code changes; develops and proposes new engineering practices;

and develops and improves mechanisms to transfer results of its research to the ultimate user. The Laboratory consists of the following centers:

Applied Mathematics — Electronics and Electrical Engineering2 — Manufacturing

Engineering — Building Technology — Fire Research — Chemical Engineering2

THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts

research and provides scientific and technical services to aid Federal agencies in the selection, acquisition, application, and use of computer technology to improve effectiveness and

economy in Government operations in accordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders, and other directives; carries out this mission by managing the Federal Information Processing Standards Program, developing Federal ADP standards

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'Headquarters and Laboratories at Gaithersburg, MD, unless otherwise noted; mailing address Washington, DC 20234. 'Some divisions within the center are located at Boulder, CO 80303.
Mationat Bureau of Stfsotosa Fire Research and Safety O^T i 1982

<\&K O.CC CATC

Proceedings of the Fifth Joint Panel Meeting of the

U.S. -Japan Cooperative Program in Natural Resources held

October 15-24, 1980, at the National Bureau of Standards,

Gaithersburg, MD

Edited by:

Joyce E. Chidester

Center for Fire Research

National Engineering Laboratory

National Bureau of Standards

Washington, DC 20234

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Issued September 1982

f
Library of Congress Catalog Card Number: 82-600580

National Bureau of Standards Special Publication 639

Natl. Bur. Stand. (U.S.), Spec. Publ. 639, 394 pages (Sept. 1982)

CODEN: XNBSAV

Papers in this volume, except those by National Bureau of

Standards authors, have not been edited or altered by the National

Bureau of Standards. Opinions expressed in non-NBS papers are those of the authors, and not necessarily those of the National

Bureau of Standards. Non-NBS authors are solely responsible for the content and quality of their submissions.

The mention of trade names in the volume is in no sense an endorsement or recommendation by the National Bureau of

Standards.

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TABLE OF CONTENTS

Page

ABSTRACT vi

AGENDA vii

LIST OF PARTICIPANTS ix

MINUTES xi

1. PROGRESS REPORTS 1

Recent Development of Fire Retardance 2

F. Saito

Recent Advances in Flame Retardance Research 11

F. Clarke

Building Systems and Smoke Control, T. Wakamatsu 17

and Y. Morishita

Detection in U.S.A. 1979-1980, I. Benjamin 22

Human Behavior, S. Horiuchi and T. Jin 26

Fire Detection and Smoke Property, J. Miyama 31

Discussion of Presentations on Progress Reports 39

2. ARSON AND FIRE INVESTIGATION 43

Early Intervention in Arson Epidemics: Developing a . . . 44

Motive-Based Intervention Strategy, C. Karchmer

Incendiary Fires in Japan, T. Kawamura 64

Discussion of Presentations on Arson 67

iii
Page

TOXICITY OF COMBUSTION PRODUCTS 71

Basic Concept of Toxic Hazards in Building Fires, 72

K. Kishitani, F. Saito and S. Yusa

Preliminary Comparison of Combustion Model in 88

Toxicity Test Method with a Large Scale Fire Scenario,

M. Birky

Study of Toxic Gas Generated During Combustion — In ... 104

Case of Natural and Artificial Lawn, Y. Nishimaru and

Y. Tsuda

Discussion of Presentations on Toxicology 116

ADVANCES IN SPRINKLER TECHNOLOGY 121

Life Safety Factors Involved in the Use of Sprinklers, . . 122

J. O'Neill

Sprinkler Technology and Design in Japan, J. Unoki .... 155

Advances in Residential Sprinklers, H. Kung 176

Discussion of Presentations on Sprinkler Technology .... 225

FIRE MODELING 230

Laminar Wake Flame Heights, C. Kinoshita and P. Pagni . . . 231

Mr. Hasemi presented a condensed review of manuscripts on recent advances in fire research in Japan. These papers are included in the Bibliography Of Support Papers (page 379).

The Computer Fire Code, H. Emmons . 236

Recent U.S. Progress in Mathematical Modeling of Fire . . . 248

Enclosures, R. Friedman

Discussion of Presentations on Modeling 260

iv
Page

6. SMOLDERING 265

Modeling of Smoldering Combustion Propagation, 266

T. Ohlemiller

Thermal Processes in the Smoldering of Wood, 308

T. Handa, S. Yoshizawa, M. Morita, M. Fukuoka,

H. Tsushima, Y. Hashizume and T. Nakamura

Discussion of Presentations on Smoldering 365

FINAL SESSION REPORTS 367

Report on Progress Report Session, F. Clarke 368

Report on Technical Session on Arson and Fire 370

Investigation, I. Benjamin

Report on Technical Session on Toxicity of 371

Combustion Products, J. Bryan

Report on Technical Session on Advances in 373

Sprinkler Technology, T. Jin

Report on Technical Session on Fire Modeling, 374

T. Handa

Report on Technical Session on Smoldering, 375

R. Friedman

RESOLUTIONS 376

SUPPORT PAPERS, Bibliography Of 379

v
ABSTRACT

The Fifth Joint Panel Meeting of the United States - Japan Panel on Natural Resources (UJNR), Fire Research and Safety, was held at the

National Bureau of Standards in Gaithersburg, MD, from October 15

through 24, 1980. The meeting consisted of in-depth technical sessions

on arson and fire investigation, toxicity of combustion products,

advances in sprinkler technology, and fire modeling. Progress reports

briefly covered fire retardance, building design, smoke control, human

behaviors in fires, and fire protection. Two days of informal sessions

were held on toxicity, human behavior, detection and smoke properties,

sprinklers, smoldering, and fire modeling. This meeting was held in

conjunction with the Center for Fire Research's Annual Conf erence* which

included United States presentations of related technical subjects. The

proceedings include the technical papers presented at the UJNR meeting

along with the ensuing discussion and the summary reports prepared by

each session chairperson.

The first meeting of the UJNR Panel on Fire Research and Safety was held

in Washington, DC, from April 7-8, 1976, where the current activities

in the United States and Japan on fire research and safety were introduced. After this exchange, the following six topics were selected for

initial cooperation: toxicity, building systems, human behavior, smoke

control, detection and smoke properties, and modeling of fire.

The participants resolved that the sixth meeting, to be held in Tokyo,

would cover the following topics in-depth: (1) building systems and

smoke control, (2) human behavior, (3) fire modeling, and (4) toxicity.

Progress reports will be submitted in the areas of human behavior, fire

modeling, toxicity, sprinklers, detectors, fire and smoke retardants,

fire investigation techniques, and building systems and smoke control.

Key words: arson, building design, combustion products, fire investigation,

fire modeling, fire protection, human behavior, smoke control,

smoldering, sprinkler systems, toxicity.

*Fourth Annual Conference on Fire Research, Martinez, I., Cherry, S.,

Editors, Nat. Bur. Std. (U.S.), NBSIR 80-2127-1, 1980.
AGENDA

THE FIFTH JOINT PANEL MEETING

UJNR Panel on Fire Research

October 15-24, 1980

Wednesday, October 15

9:00 a.m.

10:15

10:30

12:30 p.m.

1:30

5:00

Thursday, October 16

9:00 a.m.

12:30 p.m.

1:30

Session Chairman - Dr. F. B. Clarke

Opening Session

Welcoming Remarks

Selection of Chairmen and Recorders

Introduction of Panel Members

Coffee and Tea Break

Progress Reports on: Fire Retardance

Building Design

Smoke Control

Human Behaviors in Fires

Fire Protection

Lunch

Session Chairman - Mr. I. A. Benjamin

Technical Session

"Arson and Fire Investigation"

Adjournment

Session Chairman - Prof. J. J. Bryan

Technical Session

"Toxicity of Combustion Products"

Lunch

Session Chairman - Dr. T. Jin

Technical Session

"Advances in Sprinkler Technology"

5:00 Adjournment

vii
Friday, October 17

9:00 a.m.

Agenda, Continued

Session Chairman - Prof. T. Handa

12:30 p.m.

1:30

5:30

October 20 and 21

October 22, 23, 24

Friday, October 24

1:00 p.m.

4:00 p.m.

Technical Session - "Fire Modeling"

Lunch

"Fire Modeling" continued.

Session Chairman - Dr. R. Friedman

Technical Session - "Smoldering"

Adjournment

Informal Sessions

Toxicity

Human Behavior

Detection and Smoke Properties

Fire Modeling

Smoldering

Sprinklers

Center for Fire Research ANNUAL CONFERENCE

Technical Sessions included:

Human Response to Fire Detection Alarms

Human Behaviors in Fire

Building Design and Smoke Control

Toxicity

Session Chairman - Dr. T. Wakamatsu

Closing Joint Session

Reports of Technical Session

Resolutions

Adjournment

viii
LIST OF PARTICIPANTS

The Fifth Joint Panel Meeting

UJNR Panel on Fire Research

October 15-24, 1980

PANEL MEMBERS - Japan

Dr. Takao WAKAMATSU (Chairman)

Ministry of Construction

PANEL MEMBERS - U.S.

Dr. Frederic CLARKE (Chairman)

National Bureau of Standards

Dr. Fumiharu SAITO

Ministry of Construction

Mr. Yasaburo MORI SHITA

Ministry of Construction

Mr. Yuji HASEMI

Ministry of Construction

Dr. Tadahisa JIN

Ministry of Home Affairs

Prof. Jun MIYAMA

Sophia University

Prof. Yoichi NISHIMARU

Yokohama City University

Prof. Takashi HANDA

Science University of Tokyo

Mr. Tetsuhiko KAWAMURA

Japanese Association of

Fire Science and Engineering

Mr. Juzo UNOKI

Japanese Association of

Fire Science and Engineering

Mr. Irwin BENJAMIN

National Bureau of Standards

Prof. Howard EMMONS

Harvard University

Prof. John BRYAN

University of Maryland

Dr. Raymond FRIEDMAN

Factory Mutual Research Corp.

Dr. Patrick PAGNI

University of California

Mr. Philip SCHAENMAN

U.S. Fire Administration

Dr. Takashi KASHIWAGI (Secretary)

National Bureau of Standards

Dr. Tadahiro ISHII (Technical Coordinator)

Science University of Tokyo

ix
Invited Speakers

Invited Speakers :

Dr. Hsiang-Cheng KUNG

Factory Mutual Research Corporation

Mr. Clifford KARCHMER

Battelle Institute

Dr. Merritt BIRKY

National Bureau of Standards

Dr. Thomas OHLEMILLER

National Bureau of Standards

Mr. John O'NEILL

National Bureau of Standards

Invited Guests :

Mr. H. KURIHARA

Science Counselor

Japanese Embassy

Dr. K. HEINRICH

Office of International Relations

National Bureau of Standards

Dr. J. LYONS

National Engineering Laboratory

National Bureau of Standards

Mr. A. GLEASON

Bureau of Alcohol, Tobacco and Firearms

Department of Treasury

Mr. R. CHAIKEN

Bureau of Mines

U.S. Department of Interior

Dr. R. MYERS

University of Maryland

x
Fifth UJNR Meeting

Minutes of the Opening Session:

Dr. Frederic B. Clarke, Chairman of the United States delegation, opened

the joint session by welcoming the delegation to the National Bureau of

Standards (NBS). He then introduced Dr. John W. Lyons, Director, National

Engineering Laboratory, NBS (and former Chairman of the UJNR U.S.

delegation). Dr. Lyons pointed to the great progress made by the Panel

in the first four meetings, and voiced his belief that present and

future sessions would also be fruitful.

There followed the selection of Chairmen and recorders for the sessions.

The Panel voted unamiously to make the following individuals session

chairmen:

F. Clarke (USA)

I. Benjamin (USA)

J. Bryan (USA)

T. Jin (Japan)

T. Handa (Japan)

R. Friedman (USA)

T. Wakamatsu (Japan)

Opening Session

Arson and Fire Investigation Session

Toxicity of Combustion Products Session

Advances in Sprinkler Technology

Fire Modeling Session

Smoldering Session

Closing Session

H. Emmons (USA)

F. Saito (Japan)

- Resolution Committee

Panel members were introduced. The minutes of the Fourth Joint Panel

Meeting in Tokyo were approved and will be printed in Proceedings to

be published by the Japan delegation.

The agenda for the week was then reviewed in detail and approved with

minor modifications. Procedural details for the sessions were discussed

fully.

The opening session adjourned after the foregoing discussions were

completed.

xi

1, PROGRESS REPORTS

i
PROGRESS REPORT

Recent Development of Fire Retardance

by F. Saito

To decrease the probability of fire-outbreaks and prevent

fires from developing are primarily important in the field of fire

prevention technology. Compartmentation of fire, smoke control and

evacuation are also important subjects to be studied.

In Japan, we have enforced the regulations so that interior

materials, such as linings, curtains and carpets applied in public

buildings or tall buildings, from which people will take a long time

to evacuate, should be resistant enough to fire, having a certain

level of flame retardancy or fire retardancy depending on the place

where the material is applied. The methods for evaluating flame and

fire retardancy of these materials have been already established.

Flame retardant materials: char area, after flame (curtains,

and carpets)

Fire retardant materials: heat release, smoke generation,

toxicity (linings)

The methods of flame and fire retardant treatment tc meet the

standards prescribed in the regulations are being developed. In this

paper, flame and fire retardant technology, their defects and profits

are briefly discussed.

1. Production of flame retardant chemicals

Table 1 shows a statistical data of the amounts of the retardant

chemicals used.

2. Technology for flame retardant treatment

It is needless to say that chemicals and treatment methods have

to be selected according to a material and performance level for fire

protection required.

2

I
LOI method has been adopted in many research laboratories because

this method is easy to be applied and gives accurate values for evaluating

efficiency and synergistic action of chemicals.

A defect of this method, however, lies in the difficulty in

correlation between LOI values and the ones obtained by our national

standard method. Therefore it is difficult to decide the type and

the proper amount of chemicals to be used by LOI method.

Flame retardant: Cellulose-type curtains concerned, additive

type flame retardant in which phosphoric ester are dominant, are mainly

used and small amount of inorganic type chemicals, in spite of their

poor light durability but owing to their inexpenslveness , are also

found in market. As cleaning test is now enforced to evaluate curtains,

which are usually washed, after treatment is studied to pass the test.

Fire retardant: As legal regulations of fire protective materials

in Japan are considerably strict, it is very rare that organic materials

are made noncombustible only by the treatment of fire retardant chemicals.

Adding large amount of inorganics or treating surface material is a common method to be taken in Japan. Fire retardant is often added in

adhesives, in case of bonding organic lamination on inorganic base

layer

For example, in case of wallpapers, a fire protective material

should be used as a base material. Wallpaper whose weight is designated

according to the classified fire protection properties required should

be applied on base material, using adhesive which contains fire retardant

from 1 to 3% in dry weight content

In this case the weight of phosphoric ester to be used should be

a dry weight of 10 to 20% of the weight against the original wallpaper.

3
3. Future work

1) Plastic foams

In 1978, a lot of firemen were wounded in a fire of warehouse

whose insulation was made of poly-urethane foam. The backfire caused

by poly-urethane insulation was a main reason for' such unfortunate

injury. The material was classified as a self-extinguish type by

ASTM test method.

The cause of the fire-outbreak is considered that high temperature

droplet of welding penetrated into the insulation layer and combustion

was taken place inside the plastic foam.

In this case, thermal insulating property of this material acted

as a negative factor. Backfire occured when the firemen opened the

door of the warehouse, because the building, which has little opening,

accumulated large amount of smoke and combustible gases.

After that, a method of evaluating plastic foams in view of such

danger has been established, but other insulation materials which will

be used in near future should be also studied.

2) Evaluation for fire retardant chemicals

The type and the proper quantity of fire retardant to be applied

depend on what kind of testing method is taken for evaluation.

The world-wide standard for evaluating fire retardant has not

yet been established. And how to apply the values obtained from a test to a real fire has not been clarified.

There are so many ignition sources such as cigarettes, waste

baskets, electric appliances, and stoves in circumstance. From the viewpoint of fire protection, probability of turning such substances into

primary ignition sources should be kept as low as possible.

However, intensity of thermal load that a material receives from

these various ignition sources has not been clarified.

4*
As shown in Figs 1 to 3 S thermal load that a material receives

from an ignition source depends on the size of the ignition source

and the distance from it. Therefore, it is necessary to know the

extent of fire retardant effectiveness expected, according to the

size of the ignition source and the distance from it.

To extinguish a fire on their way of developing, prevent a flashover or at least delay- a flash-over; these are most important in

preventing building fires. Duration from a fire-outbreak to a flashover is not always proportional to the size of the ignition

source, even if the materials are the same as shown in Figs 4 and 5-

Although, researchers in other fields may give a fruitful solution,

researchers of fire retardant should be eager to solve these problems.

3. Durability of fire retardant materials

Materials, according to their end-use, are used under various

circumstances

It is needless to say that materials have to possess various

properties depending on their purposes. Besides that, fire protective

materials should possess fire protection properties.

It means that their own general characteristics should not be

degraded due to the treatment of chemicals and the fire protection

properties should not be reduced with time. At present, however, there

are few testing methods which require long lasting durability of fire

protecting efficiency. A proper method for evaluating such durability

should be developed.

At present, basic researches for evaluating durability are being

promoted in Japan, in such a manner that a material is exposed to light

under glass, or immerced in water.

5
Table 1.

Products of Fire Retardant Chemicals for Plastics (Building Materials)

type amount of use (ton/year)

Cl system 6 Br system 439

alkyl-phosphate 2323

phosphoric acid-urea 280

total 3048

Table 2. Products of Fire Retardant Chemicals for Fabrics

type number of manufacturers ratio (%)

inorganic compounds 26 35

complex inorganic compounds 24 32

organic mono or dis alkyl

phosphoric acid 8 11

other 16 24

Table 3. Smoke Generation from Fire Retardant Poly-Urethane Foam

weight

(22x22x0

.

(g)

5 cm)

chemicals smoke generation

per unit area

L.O.I

5. 83 33 17.0

6.76 additive type 54 22 .0

5.82 additive + reaction type 40.5 21.5

5.43 reaction type 22.5 23.0

6.74 M D I 22 .5 20 .0

6.66 M D I 16.8 20.5

Table 4. Gas generation from Poly-urethane Foam (mi/g)

CO CO? HCN NO +NO*,

PVC-laten 130 270 0.24 0.08

additive+reaction 47 74 0 . 33 0.12

type

reaction type 26 66 0.35

control 63 71 0.43 0.07

6
C T3 O U

•H "3

a, m

o o

(oas • _uio/ibo>i) A-[ddns

7
Table 5. Smoke Generation from PVC (Ministry of Construction Method)

PVC film chemicals

thick (mm) type Ph Px C.A

0 .

45 . 0-60 .

0.25 epoxy 3 55

0.25 D 0 P 20 58 .

0.21 D 0 P 30 31.5

0 . 19 D 0 P 40 33.0

0 . 19 D H P 20 54 .

0.22 D I D P 20 49 .

0.24 Sb203 5 72 .

0.25 Sb*03 10 75 . 0

0 .

CaC03 xJ 39 .

0.25 CaC03 30 63.0

0.25 CaC03 30

Sb203 5 53.4

0.24 asbestos 20 73.5

0.23 Sb203 5

asbestos 20 51.0

D 0 P :Dioctyl phthalate C6H4 (COOC8H17)

D H P :Diheptyl phthalate ,-r-COOC7Hl5

^tOOC7Hl5

D I D P :Diiasdecyl phthalate (CH2) 4 (COOC10H21)

5-

• FH : 3.0mnr ° PW : 5.5mm

8*

K> 50 100

Burning Rate of Crib (g/min)

15

S 10

• o

o

«•».

O RHS Model e SHSA Model

x shl Model

'0 10 20 30 40 50

Volume of Model (m3

) / Burning Rate of Crib (g/min)

Fig. 2 Relation Between the time to reach F.0. and

the Burning Rate of Ignition Source

8
Fig

Flame Profile VS Distance from Corner

2*

(cm)

Fig. 4. Flame Profile VS Distance from Wall

7M.

M

O!

<U 3: |v L

l

i i

Distance 10 20 75 I? SO

Size of Pan 2? ^ 20

(cm).

9
Fig 7 CO Gas Concentration VS Time

10
PROGRESS REPORT

RECENT ADVANCES IN FLAME RETARDANCE RESEARCH

By Frederic B. Clarke

The purpose of this update is to comment upon some of the significant

developments in this field which have taken place since the last UJNR Panel

meeting

At that time, we surveyed some of the newly- emerging techniques which

dealt directly with the condensed fuel phase and the earliest stages of

flame chemistry. The past 18 months have shown that several of these

continue a great deal of promise for the elucidation of fire retardance.

1. New Instrumentation

A. Opposed-Flow Diffusion Flame

It has been shown that the opposed flow diffusion flame is a useful

tool for the better understanding of polymer combustion.

Sawyer and co-workers have studied the burning characteristics and the

flame structure of poly (ethylene) in an opposed flow diffusion flame near extinction conditions. Using appropriately designed burners, sampling

perturbations can be minimized. Compositions and temperature profiles

can be made similar in the radial direction, which confirms predictions

and simplifies the modeling of the opposed flow diffusion flame.

Oxygen was found on the fuel side of the diffusion flame, and carbon

monoxide levels at the flame are above equilibrium. It means a departure

from collapsed flame model. Oxygen transport to the surface is important

because it can result in exothermic surface oxidation reactions and increases

the fuel pyrolysis. The difference between oxygen diffusion rate to the

surface and the rate at which oxygen is transported away from the surface

by the pyrolyzing polymer was calculated. The result of the energy

release calculation estimated that the surface oxidation could provide

11
at most twenty percent of the energy required for depolymerization.

This result suggests that heat transfer to the surface from the flame

rather than surface oxidation controls the pyrolysis, and therefore, burning

rate

B. Soot Formation

At the last UJNR meeting, we mentioned work about to begin on soot formation

in flames. The formation of soot in a combustion environment leads to

dramatic and important consequences. In large fires, the thermal radiation

from soot is the dominant energy transfer mode for pyrolysis and flame

spread. Inhalation of soot poses serious health hazards due to absorption

of toxic gases, and heavy smoke production in a fire hinders escape due

to visual obscuration. It is clear that a fundamental understanding

of soot formation processes would greatly aid in developing methods for

reducing the amount of soot produced and in controlling its properties.

One of our principal goals is to develop a detailed understanding of soot

formation processes in flames. The early chemistry is not well understood, and several proposed models have yet to be validated or disproved.

We have recently discovered that in rich hydrocarbon flames, just on the

lean side of the first observable soot luminosity, a laser induced ionization

signal can be detected which is critically dependent upon the stoichiometry

and position. Further studies have indicated that we are observing surface

o heating and ionization of small soot particles (diameters of 10-20A) , which

are most difficult to detect by laser scattering methods. In our experiments an electrode is immersed in a premixed or diffusion flame and

a pulsed laser induces an increase in ionization some distance away.

Under the influence of an applied electric field, the resulting positive

ions drift to the electrode; their average and differential velocities

can be measured with high accuracy as a function of the laser beam-toelectrode distance. From these measurements the mobilities of the

ionized soot particles can be determined, and one can estimate the

corresponding molecular weight (~ 5000 amu) and size.

12
We are now able to readily track very small soot particles in a variety of

flames. Future work will concentrate on the effects of fuel structure and

the correlation of our observed ionization signals with scattering and

fluorescence measurements.

The Application of Existing Instrumental Techniques to Fire-Related Problems

A. Solid Phase Nuclear Magnetic Resonance:

For many years, nuclear magnetic resonance (NMR) of liquids and

solutions has been a powerful tool for chemical analysis. Until

recently NMR of solids has been of little use to chemists because

of poor signal to noise and broad resonance lines which obscure the

chemical information desired. The technique of cross polarization

improves the sensitivity of NMR of solids and the combination of high

power decoupling and magic angle sample spinning improves the resolution

13

such that the C NMR linewidths of many organic materials are a few Hz.

13 This approaches the resolution obtainable in C NMR of liquids.

Unfortunately, the inherent inhomogeneity of solids precludes obtaining

linewidths as narrow as are found in liquids where isotropic motion

provides averaging and consequent narrowing of NMR resonances.

Presently several studies are underway in the Center for Fire Research

aimed both at understanding the basic physics of NMR in solids and at

applying the technique to characterization of solid materials. A series

13

of experiments have been completed on the identification of the C NMR

peaks in cellulose. These studies illustrate the sensitivity of NMR to

morphology and crystalline structure. More studies are planned to add

to our understanding of the physical structure of cellulose. Model

studies on various simple sugars have been started in an attempt to

quantify the chemical shift of the resonance lines due to hydrogen

bonding and conformational changes. The simple mono and disaccharides

are excellent model compounds because their solution NMR is well understood and many of the crystal structures are known. Solid state NMR is

13
currently being used to observe the chars from pyrolysis of cellulose in

nitrogen and from smoldering of cellulosic loose fill insulation. These

studies are just starting, with the expectation that we will be able to

observe intermediate compounds in pyrolysis and that we will be able to

distinguish the smoldering of the cellulose from that of the lignin in

the smoldering of paper. It is already clear that the large number of

free radicals in the chars make these experiments somewhat difficult but we are able to clearly see that a char generated by pyrolyzing cellulose

at 625K is primarily aromatic in chemical structure.

B. The Mechanism of Cellulose Smoldering Retardance by Sulfur

Molecular sulfur is known to retard smoldering in cellulose and cellulosic

materials. At present there is little commercial use of sulfur as a smoldering inhibitor because of the odor and problems of application. An

understanding of the detailed chemical mechanism of this retardance would

provide a starting point for looking for other compounds which could be

used to retard smoldering in cellulose.

The approach to this problem involved multiple instrumental techniques

including: x-ray fluorescence, electron paramagnetic resonance, mass spectrometry, thermal analyses and simple measurement of rates and

temperatures of smoldering. Using thermal analysis it was shown that

molecular sulfur is not simply acting as a heat sink through its various

phase transitions. The direct sampling mass spectrometric experiments

show that the sulfur is primarily oxidized in SC^ and COS and that oxygen

depletion by reaction with sulfur is not the mechanism of retardance.

Electron paramagnetic resonance with careful spin counting, showed a large decrease in the number of free radicals in the char of material

treated with sulfur. The x-ray fluorescence measurement of sulfur

remaining in the char showed a significant amount of sulfur bound to

the carbon skeleton of the char. The quantity of bound sulfur is

comparable to the quantity of free radicals lost by sulfur treatment.

The conclusions from this work are: sulfur acts as a radical scavenger,

14
reacting with free radicals generated in the pyrolysis step of the

cellulose smoldering. This radical scavenging stops the free radicals

from further reaction thus reducing the amount of heat generated for

further pyrolysis. One of the important properties of sulfur is that

vaporization of the sulfur occurs between 490 and 650K so that it is

mobilized and available for reaction at temperatures where the pyrolysis

of cellulose is beginning to generate large numbers of free radicals.

C. Antimony-Halogen Interactions

Early organohalogen/antimony oxide research efforts were primarily

concerned with determining optimum antimony to halogen and antimony oxide/

organohalogen to polymer substrate ratios for specific flame retardant

applications. From these studies the concept of an antimony /halogen

synergistic effect was developed. While this concept has been accepted

for many years, we have only recently begun to understand some of the

mechanistic aspects of this interaction. More recently, mass spectrometric

techniques have been used to monitor the formation of volatile antimony

halide and oxyhalides as a function of temperature. Brauman, et. al.

,

studied a wide variety of antimony oxide/organohalogen combinations using

a wide variety of experimental techniques and concluded that the volatilized

antimony was the dominant retardant species in the gas phase. Yeh and

Drews used calorimetric techniques to measure the efficiencies of antimony

oxide/organohalogen finishes and additives. Their data show that while

the efficiencies of the antimony/halogen systems were greater than those

measured for the halogen alone, the calorimetric responses were similar.

While these data have shown that the concept of a antimony/halogen

synergism appears to be a valid one for many different organohalogen/

antimony oxide combinations, the solid state chemistry involved in the

generation of the volatile antimony species must be quite different.

Accordingly, research to determine the importance of the solid phase

15
interactions which occur among antimony oxide, organobromine additives

and polymer substrates in the solid phase to the overall system chemistry

in combustion is now in progress. The role of the polymer substrate

in the generation of the volatile antimony species is of particular

importance in this work.

For the future, research designed to increase our understanding of the

solid phase chemistry of these retardant systems can be expected to continue.

In addition, efforts to more completely elucidate the flame chemistry

of antimony/halogen inhibited flames will be necessary to answer some of

the questions posed by the calorimetric data of Drews.

16
Progress Report

on

Building Systems and Smoke Control

by

T.Wakamatsu and Y.Morishita

I. Building Systems

The interests on the subjects to develop the Total Evaluation

and Design Systems of Fire Protections in Buildings are still more

growing in Japan. At the consultative meeting on archtectual design

and also at that on fire prevention which were held at the time of

the Annual Meeting of Archtectual Institute of Japan, September 198 0,

the necessity to solve this subject was emphasized from the view

point to make the fire safety regulations synthetic and clear,

which are now only becoming complex and multiplex.

As reported at the U.J.N.R. 3rd Joint Meeting, the researches

on this subject are. conducted mainly at Fire Safety Systems Committee

which was. founded in April 1977 by Japanese Association of Fire

Science and Engineering. tl]

The principal results of the researches which had been conducted

in this committee until December 1979, were published as the

Occasional Report No. 3 of Japanese Association Fire Science and

Engineering.

The contents of this repot is attached as Appendix I.

The 10 studies out of 13 ones which were printed in this report

were already reported at the U.J.N.R. Joint Meeting, so the summaries

of unreported 3 studies are introduced -here. ( (a) -(c) ) Besides these studies which were printed in this occasional

report, several studies have been done on this subject recently.

They are also introduced in this paper. ( (d) - (g) )

(a) Concepts and Methods on Optimization of Fire Safety Planning

( Y.Aoki ) [2]

The Concepts and methods on optimization of fire safety plannings are examined in this paper. First, fire losses are classified

into the reparable loss and the irreparable one by using the state

transition model, and the method to indicate these losses by the

two dimensional vector is proposed. Further, the concepts on optimization of fire safety planning is analyzed by dealing them as two

dimensional optimization problem from the view point of the decision

thory, and the optimization method of fire safety planning is

proposed.

(b) Some Discussions on Interior Finishing Materials and/or their

Components for Building Fire Safety ( S.Sugawara ) [2]

The significance oi; interior fire protective methods should

be evaluated by the contributivity to the total systems for fire

safety design. From such a point of view, it is necessary to accumu17
late the real fire data which will give useful informations about

the contributivity of interior finishing. In this paper, the establishment of " International Fire Information Center " is proposed

for the purpose to develop a new automatic data processing system

,

etc. Further, some stochastic approaches are tried in order to

estimate the contributivity for fire development.

(c) Engineering Design for Structural Fire Safety ( H.Saito ) [2]

There are several proposals for the engineering design of

structural fire safety which are different in the setting of fire

characteristics or in the design method for fire resistive performance of structural elements. In this paper, after such recent status

of design for fire resistance is introduced, the optimum value of

fire resistance design is discussed. Further, the author refer to

the necessity to examine the factors which have the effects on the

reliability of fire resistance design, such as the maintenance

conditions, the durability of fire resistance, etc.

(d) Development of Computer Programme for the Evaluation of Fire

Protection Performance of Dwelling Houses ( T.Tanaka ) [3] , [4]

In relation to the evaluation method for fire protection

performance of dwelling houses which has already been reported at

the U.J.N.R. 4th Joint Meeting, the computer programmes for the

evaluations were developed on the prevention performance against

inter-house -fire spread and on the evacuation performance. The

programmes were applied to some examples of dwelling houses, and

some problems on such evaluation method were discussed.

(e) Reliability Analysis of Network Systems ( M.Kobayashi ) [5]

Network systems can be applied to the examination of the functions and the configurations of evacuation routs in buildings, etc.

In this paper, the computer algorithm is developed in order to

estimate the reliability of a network system which is expressed

by nodes and links, if the abilities between adjacent two nodes are

given in probability. Using the methods developed here, important

links and optimum configurations of networks could be obtained as

well as reliabilities even though their structures are considerably

complex.

(f ) Study on the Fire Protection Performance of a Fire Preventing

Zone with Two Glass Doors ( T.Tanaka ) [6]

In place of fire proof doors ordinarily used for preventing fire

spread in buildings, it is now planned to use "fire preventing zone"

composed of two doors with large glass panes and fire resistance area

between them, for the convenience of fire extinguishment activities,

occupants* evacuation and prevention of smoke spread. In this paper,

the performance of "fire preventing zone" is examined, by developing

the calculation method of thermal radiation heat transfer through it.

The results show that it is practically possisible for the zone to

prevent the thermal radiation heat transfer caused by fire more effectively than fire proof steel doors of Class A, provided that the

zone is appropriately designed.

(g) Evaluation of Fire Extinguishment Devices by Paired Comparison

Method ( Y.Morishita ) [7]

The questionnaire on the effect of the combination of three

18

/
kinds of fire extinguishment devices was made on the experts of

fire research in BRI, in which the paired comparison method was

used for the estimation. From this result, the main effect and the

interactions of these devices were estimated. Further, the differences

of judgements among evaluators were shown by analysing them with

" Cluster Analysis " and " Principal Component Analysis " . Such

results of the analyses are expected to be useful informations when

the evaluation method of such devices is determined by the discussions of experts.

Literatures

[1] " Present Status of Research on Fire Safety Systems for

Buildings ", Progress Report on Building Systems, The U.J.N.R.

3rd Joint Meeting, March 1978

[2] " Evaluation of Fire Safety in Buildings ", Occasional Report

No. 3 of Japanese Association of Fire Science and Engineering,

Dec. 1979

[3] Tanaka,T. : " Protection performance against inter-house fire

spread " ( in Jaoanese ) . Internal report of Fire Safety Systems

Committee, Dec. 197 9

[4] Tanaka,T. : " Appliacation of the evaluation system for evacuation safety performance to concrete examples " ( in Japanese )

Internal report of Fire Safety Systems Committee, Jan. 198 0

[5] Kobayashi,M. : " Reliability Analysis of Network Systems "( in

Japanese ) , Papers of the 15th Scientific Reseach Meeting, Nov.

198 0, City Planning Review, The City Planning Institute of

Japan, ( in printing )

[6] Tanaka,T. : " Study on the Fire Protection Performance of a Fire Preventing Zone with Two Grass Doors - Theoretical Calculation of the Thermal Radiation Heat Transfer through a Fire

Zone " ( in Japanese ) , Transactions of Architectural Institute

of Japan, Number 28 0, June 197 9

[7] Morishita,Y. : " Evaluation of Fire Extinguishment Devices by

Paired Comparison Method " ( in Japanese ) , The Spring Meeting

for Presentation of Researches in BRI, May 1930

19
II. Smoke Control

The studies on smoke control in Japan have been developed for

the purpose of establishing the prediction method of smoke movement

and the evaluation method of smoke control systems, by means of

which more rational design of smoke control systems will be possible.

In these studies, a few field experiments to validate the theory

are included, but the theoretical approaches have been centered so

far.

Recently, the priority of the studies in this field is moving

to the experimental approaches by the fact that the theoretical

approaches have achieved an expected goal and that the new Full

Scale Fire Testing Laboratory for smoke movement and its control

was built in BRI, Tsukuba. The main purpose of these experiments

is to validate the theory, to supplement it, to comfirm the effectiveness of various smoke control systems, etc.

1. Field Study in Tsukuba

The laboratory for smoke test in Tsukuba has 7 stories and is

equipped with facilities and equipments for smoke control such as

fans for air supply and smoke exhaust. The experiments using this

laboratory started from April last year. In last year, first, the

flow resistances of the small openings of doors, windows, etc. and

the vertical shafts such as staircases were measured. Then, the

preliminary experiment was conducted, through which the experimental

values were compared with the theoretically caluculated ones concerning the pressures and the current velocities at the points

significant on smoke control. This year, the experiments on free

spread of smoke are conducted on 80 cases combinating the conditions

such as wind pressures ( controlable ) , the position of smoke

generation, flow path structures composed of opening and shutting

doors, windows , vents , etc. In these experiments, smoke candles and

methyl alcohol are principally used for the smoke generation. The

combustion of wood fuel and SF 6 as a tracer gas are now planned to

be used.

On and after next year, a series of experiments is planned in

order to examine and confirm the effectiveness of various smoke

control systems.

2. Field Tests in New Buildings

The design of smoke control systems of two high-rise buildings

recently constructed at Shinjuku, Tokyo, namely, Shinjuku Nomura

Building ( completed June 198 0, with 50 stories and 5 basements ) and Shinjuku Center Building ( completed Nov. 1979, with 55 stories

and 5 basements ) , are made under the guidance of BRI , based on the

results of many case studies by computer simulation on smoke movements or the smoke control effectiveness. The field experiments for

the smoke control effectiveness were carried out on these two

buildings just after their completions. The main purpose of these

experiments was to ascertain if the function of control works as

expected at the time of design, by operating smoke control systems

under some possible fire situations. By the results of these experiments,

the function of control was ascertained to work as expected as for

Shinjuku Center Building, but for Shinjuku Nomura Building, it

couldn't be enough ascertained since the measurement of the pressure

and the current velocity was not conducted sufficiently.

20
Appendix I : " Evaluation of Fire Safety in Buildings

Occasional ReDort of Japanese Association of

Fire Science and Engineering No. 3, Dec. 1979

CONTENTS

Concepts and Methods on Optimization of Fire

Safety Planning - Yoshitsugu AOKI 1

Basic Problems on Evaluating Fire Safety in

Buildings - Yasaburo MORISHITA 10

On An Aquirement of Fire Safety in Buildings

- Yoshio MIMURA " ' 23

Development of Evaluation Method for Fire

Protection Performance of Dwelling Houses

- Takeyoshi TANAKA 41

Studies on Probabilistic Spread of Fire

- Yoshitsugu AOKI 62

Evaluation of Flashover Criteria by Using

Mathematical Fire Modelling - Yuji HASEMI 118

Some Discussions on Interior Finishing Materials

and/or Their Components for Building Fire Safety

- Shin-ichi SUGAWARA ' 131

Investigation on The Compartmentation against

Smoke Spread in Office Buildings

- Yuji HASEMI, Tomio SHIM-ADA 144

Efficiency of Fire Compartmentation

- Tetsuo MORIWAKI, Toshio EDA 155

Effectiveness of Active Fire Protection Systems

- Akio WATANABE 170

A Quantitative Assessment on Smoke Safety

- Takao WAKAMATSU 182

A Methodology for Evaluating Fire/life Safety

Planning. of Tall Buildings - Masami KOBAYASHI 203

Engineering Design for Structural Fire Safety

- Hikaru SAITO 215

21
PROGRESS REPORT

Detection in U.S.A. 1979-1980

By Irwin A. "Benjamin

Current surveys indicate that about 50% of the U.S. homes now have smoke

detectors. However, the distribution of detectors varies according to socioeconomic groupings. About two-thirds of the homes with incomes of over $20,000

have detectors compared with about one-third of the homes with incomes less than

$20,000. However, in spite of this discrepancy there has been a real increase

in the number of detectors in both these groups over the 1979 to 1980 period.

The detector industry has begun a trend toward consolidation, with several small

manufacturers going out of the business. There have been no major technical

innovations in the detection industry during the last year. New development

activity has slowed down and the Underwriters Laboratories have indicated that

their applications for approvals of new models and new designs have dropped off

radically in the recent period. A couple of years ago a residential detector

combining ion chamber and photoelectric sensing units in the same head was put

on the market. This represents the only recent development in detector technology;

and there does not appear to be a substantial growth in the sales of this combined

unit, possibly because of the increase in price.

The Underwriters Laboratories Test Method 217 which was originally published

in October 1978 is now in effect, after an initial 18 month waiting period.

This test method, now includes a smoldering test based on heating small pine

sticks on a hot plate to meet a predetermined optical density curve. The smoke

level is measured both with a photoelectric beam and also with a MIC (measuring

ionization chamber). For the smoldering test a criteria of 7% per ft. OD is

Kj

the maximum for the response of the detector. This value is being disputed as

I being too high and has been subject to discussion.

22
Some technological development is being done for commercial installations. Some

of the manufacturers have been working on developing a remote sensitivity monitoring

system so that the detectors can be checked from a central panel. Also, methods

for the continuous monitoring of detectors are being investigated. In general,

fire detectors are being combined with the energy sensing devices into an integrated

system which attempts to address the total energy problem. Likewise, for residential systems combined fire and burglary systems are being promoted. However, these

more complex systems represent only a small share of the installations.

Much effort in the past period has gone into monitoring performance of fire

detectors. One of the major studies is being conducted by the Ontario Housing

Authority, Ontario, Canada. They installed 87,000 single station detectors in

apartment units in 1976 and 77 and are checking them yearly. There are seven models

of detectors, six ionization and one photoelectric. Six of the models are U.L.

listed and one is a Canadian listed detector. From the Spring of 1977 to the

Spring of 1979, 150,000 detectors have been tested and 3,244 have been found

defective—a 2.2% overall failure rate. This failure rate seems to be consistent

for all the six U.S. detectors in the study. Recent data from Ontario has

indicated that about 5% of the detectors have been disconnected by the tenants

because of their desire to eliminate false alarms. In general, the observations

of the Ontario Housing Authority are that the ion chamber seems to be giving a

slightly higher false alarm rate. This would not be unanticipated for these

apartments which are in the range of 50 sq. meters in size. In such a small

area the ionization detector would be subject to the effects of cooking vapors.

One other recent development in the U.S. has been the promotion of what is called

ARRAS (Automatic Residential Remote Alarm Systems). One such system is

installed in Woodland, Texas in a large number of residences. The system is being
run in conjunction with a cable T.V. system. Preliminary data is starting to

come in on the effectiveness of this system; but it is still too early to

draw any conclusions. One observation however does seem to be that the ion

chambers may be giving a slightly higher false alarm rate than the photoelectric

types. It is interesting to note that the preliminary data indicates that about

30% of the apartments have had false alarms. This again is associated with a

fairly small size apartment.

Detectors do appear to be effective. Recent statistics from NFIRS (National

Fire Information Reporting System) indicate that the death rate in fires in homes

without detectors appears to be double the rate for homes with detectors.

Although there may be socio -economic factors involved in this statistic

yet it is is a good indication that the detectors are effective. In a

study recently conducted by IAFC (International Association of Fire Chiefs) fires

were studied in ten cities around the country. Their data would indicate that

the first warning of a fire in hemes having detection was given by a detector

in 40% of the cases. This indicates a very substantial achievement for detection,

particularly if one takes into account the fact that many reported fires occur

during the day time with the person directly involved with the fire.

The overall statistical data on the fire loss rate in the U.S. has not yet

reflected the effect of detectors. It is believed however that such evidence may

be premature and that it will be several years before the gross fire statistics

will reflect the fact that 50% of the homes now have detectors.

24
In summary, the past period has been one of limited technological growth and

little new research. Studies are being initiated or conducted to determine

effectiveness of detectors and identify the magnitude of the false alarm

problem.

25
PROGRESS REPORT ON HUMAN BEHAVIOR

by

S . Horiuchi and T . Jin

We would like to introduce to the reader briefly two

lines of research we have been undertaking for the past year

and a half here in Japan on the subject of human behavior at

the time of a fire.

1. STUDY OF THE SAFETY SIGN FOR EMERGENCY EXIT1 *

The markings on safety sign of emergency exit must be

simple so as to be clearly visible even from a distance, and

the indication of emergency exits must possess a concreteness

that would be immediately understandable even by a foreigner.

We have commenced research in this area in order to modify

the characters presently used in Japan ( # WO. ) to a pictograph that fulfills the above stated conditions. We solicited

generally for such pictographs and made a selection from

3,334 entries based on the following evaluative processes.

First Process :

Employing video signal technics, we excluded those

pictographs which were hard for people with deficient eyesight

to distinguish.

26
Second Process :

We eliminated those which according to the designer

were considered inappropriate.

Third Process :

We ranked the entries according to what the general

public of about 15 0 persons would find both pleasing and

appropriate in a pictograph indicating an emergency exit.

Fourth Process :

After transferring the top ten pictographs , as determined

by the third process, to panels of actual luminaire devices

and then installing these devices in corridors, we measured

the visual distance of each pictograph under normal illumination conditions.

Fifth Process :

Using the same devices as in the above, we tested the

visibility of each under smoky conditions.

Comprehensive Judgement :

After tabulating the results of the above processes,

we determined which pictographs were most effective. These

are to be found in Figure 1. This research was carried out

27
under the leadership of the Fire Defense Agency of the Ministry

of Home Affairs.

2)

T . Jin then took the pictographs which emerged from the

above tests and tested their visibility comparatively against

those indicated in ISO/TC21/SC1/DP63 09 NO .4 (Figure 2). These

results showed the Japanese-devised pictographs to be more

visible at a greater distance than the ISO-produced symbols by

about 2 0 % under normal smokeless illumination conditions and

by about 10 % under smoky conditions. Though both sets of

pictographs resemble each other in design, the symbols within

the Japanese set are superior in their simplicity, and this is

thought to be the reason for the differences found in the above

tests

2. LIMITS TO HUMAN ENDURANCE OF THERMAL RADIATION DURING FIRES 3

Y. Hasemi and K. Shigekawa measured this endurance time.

Using a Schwank burner as their heat source, they had their

test subjects stand directly facing the burner (Figure 3).

With thirty minutes as the upper limit for the exposure period,

the subject's own judgement was used to determine whether he

had reached that endurance limit at any time within the 3 0-

minute period. The incident radiant flux densities thus found

were of five kinds—1790, 1950, 2100, 2290, and 2510 Kcal/m2 h.

In addition, the clothes of the test subjects were those typically worn indoors in winter. But with two or three of the

subjects, tests were also run for the case of short-sleeve

28
garments

The relation between the incident radiant flux density

and the endurance time is given in Figure 4. It was found

2 that if the density were below 18 0 0 Kcal/m h, the endurance

time of most of the subjects exceeded 30 minutes.

3. THE ADDITIONAL RESEARCHES CONCERNING HUMAN

- BEHAVIOR AT

THE TIME OF A FIRE.

Y. Watanabe has performed experiments using a continuous

4) . maze . For subjects given only one chance in the maze, it

was found that, upon turning three corners, less than half of

the subjects could return to the starting point. However, a large number of the subjects who had walked the same course

a number of times were found to be able to return to the

starting point even after turning seven or eight corners

S. Okazaki made a simulation model concerning walking in

the case where there are markers to lead the way^

Using questionnaires, Y. Murozaki surveyed residents

evacuated from a twelve -story apartment building which had

6

caught on fire . In this apartment building, fire occurred

two times for one year.

29
REFERENCES:

1) Research Committee on Fire Safety Systems for Buildings

(a part of the Fire Protection Equipment and Safety

center of Japan): "Research Report on Pictographs

Designs for Emergency Exits" (1980)

2) Tadahisa Jin: "Lecture Abstracts from the Annual Meeting

of the Architectural Institute of Japan" (Building Construction Volume) p. 2119 (1980)

3) Yuji Hasemi and Kishie Shigekawa: "Research Report

Summaries from .the Meeting of the Japanese Association

of Fire Science and Engineering" p. 17 (1980)

4) Yuichi Watanabe: "Lecture Abstracts from the Annual

Meeting of the Architectural Institute of Japan" (Design

Volume) p. 763 (1979)

5) Shigeyuki Okazaki and Satoru Matsushita: "Lecture

Abstracts from the Annual Meeting of the Architectural

Institute of Japan" (Design Volume) p. 751 (1979)

6) Yoshiteru Murozaki and Akihiko Kokugo : "Lecture Abstracts

from the Annual Meeting of the Architectural Institute of

Japan" (Design Volume) p. 769 (1979).

30
The Progress Report

on

FIRE DETECTION and SMOKE PROPERTY

by

Dr. Jun Miyama

Professor Sophia University, Tokyo

Fumiharu Saito

Building Reseach Institute

Ministery of Construction

The progress report on Fire Detection and Smoke Property

summarizes researches, investigations, and developments in

both fields since the Fourth United State - Japan Panel on Fire Research and Safety meeting in Tokyo during February,

1979 .

The report consists of two parts; i. e., Part I is concerned

with fire detection and was described by J. Miyama, and Part

II is concerned with smoke property and was described by

F. Saito, according to their respective specialty.

Part I Part I consists of two reports on fire experiments in fullscale houses, comparative study on the absorption of visible

and infrared ray in smoke, a report on the study of beam type

smoke detectors, and several recent developments on smoke

detectors and fire alarm systems.

1.1 A fire experiment in a full-scale house for the investigation of detector's response time concerning feasibility of

extinction and refuge

The experiment was performed in a room of an evacuated tenement house to investigate time allowable for the residents to

31
extinguish a fire

it has occured in

at its incipient

their room.

stage and take refuge when

Three kind of detectors; i. e., an ionization chamber type,

phtoelectric type, and rate-of-rise and spot type were installed on the ceilling.

Fire was set to a waistpaper basket in front of a closet, whose

sliding door caught fire after about 1 minute. And fire alarm

was released after 1 minute 6 seconds by the ionization chamber type, 2 minutes 46 seconds by the photoelectric type, and

4 minutes by the rate-of-rise and spot type.

Meanwhile, after 10 minutes from the beginning the room was

filled with dark smoke, making both of extinction and refuge

almost infeasible.

It was concluded that the time allowable for extinction and

refuge should be about 6-9 minutes after the alarm had been

given, corresponding to the type of the detectors. Naturally,

the rate-of-rise and spot type gave the least time.

1.2 A full-scall fire experiment in a residence for the in-

(2) vestigation on effectiveness of residential fire detectors

The house prepared for the experiment was a twostoried resi2 dence whose total area was 104 m . There were three rooms on

the first floor including two lounges and five rooms on the

second including three bedrooms.

In the lounge where a fire was started a photoelectric type

residential detector had been installed, together with ordinary ionization chamber type, photoelectric type, and rate-ofrise and spot type to make a comparison. Detectors were similarly installed on both ceilings above a bottom and head of

the staircase.

The response time of the detectors and the sound level of the

32
residential ones were measured. Mice were also placed to detect toxic gas. A crib in one of the lounges was ignited and

the door was closed at the beginning of the experiment.

Main conclusion obtained is as follows :-

(1) There is the possibility that the alarm released on the

first floor would not be heard distinctly in the bedrooms

on the second floor.

(2) Among the detectors installed above the head of the staircase, photoelectric type is the most sensitive. Estimating from the death time of the mice, in this case, the

sleeping persons will be given 4 minutes to take refuge.

(3) In such a case, rate-of-rise and spot type should not be

used because alarm will be given too late for the residents to take refuge.

1.3 Comparative Study on the absorption of visible and infrared ray by smoke

It was made clear that the optical density of smoke due to

ISO test fire takes different value according to the type of

the optical smoke density meters used; i. e., the value of the

optical density measured in infrared ray range differs from

the value measured in visible ray range.

The experiment was performed in a test room whose dimension

is 9 m in length, 7 m in width, and 4 m in hight. The fireplace

was placed at the center of the floor and the measuring instruments were installed on the ceiling 3 m apart from its center.

The ratio k of the optical density measured with infrared

ray to that measured with visible ray was shown in Table 1.3.1

as well as k's reciplocal 1/k.

Table 1.3.1 , , test fire k 1/k

1. open cellulosic fire 0.552 1.81

2. smouldering pyrolysis fire (beech wood) 0.773 1.29

3. glowing smouldering fire (cotton) 0.591 1.69

33
4. open plastic fire 0.689 1.45

5. liquid fire (n-heptane) 0.683 1.46

This table shows that visible ray is more intensely absorbed

by every kind of smoke from the test fire than infrared ray is.

Although in the present photoelectric smoke detectors infrared

ray is used as a light emitting source, from a point of view

of taking refuge from a fire, it should be appropriate to measure optical density with visible ray regarding the fire sensitivity test under the test fire.

(4) 1.4 Study on the beam type smoke detectors

Beam type smoke detectors are considered to have various kinds

of distinctive characteristics in comparison with spot type

smoke detectors due to differences in working principle and

construction.

For example, in buildings with a high ceiling such as warehouse, aircraft hangers, theaters, museums, etc., smoke diffuses during its rise on to their ceiling, decreasing too intensly its density for spot type smoke detectors to operate.

On the other hand, beam type smoke detectors are considered

to be able to detect such thin smoke because they do detect

integral value of the diffused smoke over the span (length)

of the beam.

Furthermore, reguler maintenance of spot type scattered

throughout on the surface of high ceilings will be very difficult, while that of beam type will be easy because they can

be installed on the walls.

Even in an ordinary large building, in the corridors leading

to the kitchen area of a restaurant where it may likely present locally smoke in higher concentration, use of the beam

type would be preferable to eliminate false alarm.

Under such

have began

conditions, recently in Japan,

to develop the beam type smoke

34

several companies

detectors and a re-
search and study group was organized in Sep., 1979, consisting

of the representatives from manufacturers and government person

concerned. The group has been studying and evaluating effectiveness,

sensitivity and location of the developed detectors and conducted

a fire test, making reference to the test fire proposed by

ISO/TC21/SC3

The results thus obtained are as follows:

(a) In flaming fire, large signal values was obtained due to

rapid rise and diffusion of smoke.

(b) In smouldering fire,* no special features of the beam type

as seen in flaming fire were observed.

(c) As an intermediate report, it can be said from this fire

test, that a suitable sensitivity level of beam type smoke

detectors spanned 30 meters is between 30 - 60% and a beam pitch should be less than 14 meters.

1.5 Several recent development and improvement on fire detectors and fire alarm systems

1) An ionization chamber type smoke detector was recently

developed which can operate with two classes of sensitivity;

( 5

)

i.e., class II and class III which is less sensitive.

Thus, it has two output terminals; one is for releasing

fire alarm and another for starting related fire protection

facilities.

2) A photoelectric type smoke detector was recently developed

which will not be affected by incoming insects. ^) It is

making use of infrared ray radiated downwards into conical

space. When it is scattered by smoke, the scattered ray

is forcused on a solar cell by a lens.

3) A fire alarm system was developed, which can indicate the

( 7 ) exact location of the detector making response. It releases fire signal in audio frequency, which is proper to

the respective detectors. So that it can be discriminated

to indicate the location of the detector operated.

4) A control board for complex use was recently developed

which will be utilized to give indication about fire alarm

35
system and fire protection facility on the same indicators.

(8) Accordingly, it diminishes space occupied.

REFERENCES

1. Akio Takemoto, On the time allowable to extinguish a fire

at its incipient stage and the time to take refuge after

the alarm released by residential smoke detectors . The Committee on Fire Alarm Systems, Report No. 80-4, June 1980,

The Illuminating Engineering Institute of Japan.

2. Kazuo Kobayashi, Report on a full-scale fire experiment in

House 55 to investigate the effectiveness of residential

fire detectors . Ibid. Report No. 79-8, Oct., 1979. Ibid.

3. Koichi Endo, Comparative study on the absorption of visi - ble and infrared ray in smoke . Ibid. Repot No. 80-5, Aug.,

1980, Ibid.

4. Study on the beam type smoke detectors . Beam Type Smoke

Detectors Research and Study Group, Intermediate Report,

Aug., 1980.

5. Isao Sonehara, On the smoke detectors with two classes of

sensitivity . The Committee on Fire Alarm Systems. Report

No. 80-6, Aug., 1980, The Illuminating Engineering Institute of Japan.

6. Yoshio Furukawa, The increased reliability smoke detectors

with conically radiated ray . Ibid. Report No. 80-7, Sept.,

1980, Ibid.

7. Isao Sonehara, The new fire alarm system with proper fire

signals attached to respective detector units . Ibid. Report

No. 80-8, Sept., 1980, Ibid.

8. Yoshio Furukawa, The new complex control board serviciable

both for fire alarm system and fire protection facility . Ibid. Report No. 80-9, Sept., 1980, Ibid.

36
Part II

The purpose of research into formation of smoke particles to apply

the result to the study of fire detection and escape from fires.

For the former, characteristic relation between size distribution of

particulates, including invisible particulates, and smoke detectors has

been pursued!"^

For the latter, relation between decrease of visibility by smoke particulates and human activity in smoke has been pursued.

For a boundary study between physico-chemical and ecological surface area

of various kind of smoke particulates and artifical particles are measured

by means of Brunauer-Emmett-Teller (B.E.T.) method for getting a suggestion

. 2) 3)

to toxicity. '

In the field of smoke control design, study on smoke load in fire rooms

and on control of the flow of smoke in building have been pursued.

Although characteristics of smoke production from many materials have been

pursued by many researchers, characteristics of smoke from composit materials

are difficult to predict in fire. This seems to disturb the further development of smoke control system.

In the region of ventilation control fires, especially the stage of

developing fires, the ratio of ventilation factor to combustible materials

is more important factor than characteristics of smoke production from

materials.

For the study on smoke production, development of measurement method for

high temperature smoke in fire rooms, study on absorption of smoke particulates

on walls and coagulation during travelling in the building are also expected.

Measurement of attenuation of light intensity for the smoke density is

sueful at a low temperature atmosphere, but this method can't be useful at

37
a high temperature atmosphere as in a fire room.

Therefore, weight concentration method is substitutional for the

attenuation method in a fire room.

A linear relationship between optical density and weight concentration at

h)

flaming and smoldering combustion has been reported by T. King.

However, any linear relationship between the two could not be obtained

when plastic and wooden materials were burnt under the temperatures between

5)

600 and 800°C.

It's reasonable that ther's no relation between the optical density

method and weight concentration method for smoke. Because the main factors

for the former are size distribution and shape and surface condition of the

particulates, but the mass of particulates for the latter.

Measurement of optical density of smoke and the flow rate of smoke in a

tube or in a corridor whose thermal property is known, which is connected

with a combustion chamber in which a fire condition can be simulated, and

where the temperature is low enough to measure the light attenuation, may

be useful

.

References

1) A. Watanabe and A. Takemoto : Bui of the Prevention Society of Japan,

Vol. 21, No. 2 Feb 1972

2) F. Saito : Research Work for the Period, Building Research Institute (1970

)

3) H. Suzuki : Annual Conference on Fire Research, P6U , May (1980)

h) T. King : NBS Special Publication kll, 1973

5) F. Saito : Unpublished

38
PROGRESS REPORTS - DISCUSSION

Saito Presentation on Fire Retardance

Benjamin: Could you briefly give us an idea of what method is now

being used to evaluate plastic foam?

Saito: The size of the sample is a slick shape of 10 cm square with

about 30 cm height (demonstrated on blackboard). The cross section of

the same is drawn on the board. Alcohol cup with about 2 cm diameter

is installed. Burning of the sample starts from the inside in this

configuration.

Emmons: In Table 4, the first two columns are labeled CO, is this

correct?

Saito: No, the second column should be labeled C0 0

Clarke: For clarification in the fire in the warehouse involving

polyurethane foam, you state that the combustion took place inside

the plastic foam. Was the plastic foam covered with a fire resistance

or non-combustible material? Was the surface exposed to air?

Saito: The material was not protected. It was exposed to the air.

Clarke: We have had similar trouble in the United States and one of

the results is that building codes have retroactively changed to require

all exposed foams be covered.

39
Clarke Presentation

"Recent Advances in Flame Retardant Research"

Handa: What is the temperature used for BC measurement — 200 °C?

Clarke: At the moment, most of our temperature measurements have been

well below the combustion temperatures because of the difficulty of

finding probe materials to withstand prolonged high temperatures. At

higher temperatures we need to conduct the experiment, stop it, and put

the material into the NMR sample probe. We cannot do the experiment

in the NMR sample chamber, which would be most desirable.

Handa: Did you include pump procedure?

Clarke: No. I don't believe that works effectively for solids.

Chaiken: Regarding the amount of surface oxidation in the combustion

of solids, the measurement that Dr. Clarke refers to here is polyethylene. I would strongly suspect that in charring combustion such

as wool, coal, the amount of surface oxidation is probably considerably

greater than 20%.

40
Morishita Presentation

"Building Design and Smoke Control"

Emmons: In which publication does the measurements of the flow

resistancy of small openings of doors, windows, etc., appear?

Wakamatsu: This report has not been officially published.

Chaiken: In reference to smoke in high rise buildings and in your

laboratory, is this smoke generated by an actual fire, a large heat

source, or is it strictly from a smoke generator?

Wakamatsu: Since the building was newly built and we could not

make a fire, we generated smoke using a smoke generator and burned

methanol.

Chaiken: We are concerned with smoke in mine networks in two- and

three-dimensional configurations and how the affect of a large fire

influences any ventilation system being used. There is a very strong

coupling between the smoke and where the smoke goes, and the generation

of smoke and the fire itself. So that one designs a smoke protection

system and does not take into account the influence of fire on the air

dynamic forces you have to work with. This could cause problems.

41
Jin Presentation

"Human Behavior in Fires"

Bryan: Relative to the 20% difference in visibility between the normal

illuminating condition and 10% for smoking conditions, how smokey is

smokey conditions?

Jin: The concentration of smoke set below extinction coefficient

was 0.3 nrrl. The source of smoke was smoldering wood.

Emmons: Have you considered requiring the placement of such figures near the floor as well as near the ceiling?

Jin: The Japanese Fire Code requires that first emergency indicator

lights should be posted right above the emergency exit. Then the

blinking lights, or sirens, should be placed 20 meter intervals guiding

towards the exit. They must be posted within 1 meter from the floor.

Miyama Presentation

"Detection and Smoke Properties"

Friedman: In referring to the infrared attenuation of smoke that you

mentioned relative to the visible attenuation, do you know the wavelength of infrared that was used in that test?

Miyama: I do not have the data but it is the same that appeared in

the International Standards Organization (ISO) material.

42
ARSON AND FIRE INVESTIGATION

43
Early Intervention in Arson Epidemics:

Developing a Motive-Based Intervention Strategy

Clifford L. Karchmer

Research Scientist

Battell e Law and Justice Study Center

Seattle, Washington

44
Introduction

The reported incidence of arson in the United States has been increasing

since 1975.^ Several observers cite arson, committed for economic gain as a major

factor in the nationwide growth, while other sources attribute the rise to non2 economic problems that are related to deeply rooted stresses in society. According

to the latter interpretation, interpersonal and societ il strains give rise to a

variety of non-economic arson motives, with revenge and mindless vandalism being

cited most frequently.

The most logical explanation for the recent increase in arson centers on the

growth and accumulation of various stresses in society. These can increase, for

example, domestic disturbances and other interpersonal conflicts (affecting the

revenge motive for arson) and juvenile delinquency (influencing the vandalism

motive). Exacerbation of social, or personal problems which underly each of

these motives seems to have an impact on other motives as well. This may be so

because as the aggregate incidence of arson increases, more and more arsonsists

remain uncaught. This development may establish arson as an emotional or financial

in

outlet for a variety of stresses which ordinarily are discharged either/less harmful or by other violent means. During such a progression, contagion builds and

arson epidemics may prevail for substantial periods of time. Three-to-fiveyear spans over the past decade have been noted in such cities as Buffalo, Detroit,

Boston, New York and Seattle. However, the time series is too short to determine

whether these undulations are cyclical or random in nature.

The mix of arson motives seems to differ from one jurisdiction to another

because of variations in the types and relative frequencies of each of the various

stresses, and to differences in the size of populations which experience them.

Despite such variations, however, most of the commonly prescribed remedies treat

arson as though it were a monolithic phenomenon, unaffected by differences

45
in motives and the personal, social, and economic pressures which underly these

influences. In general, the criminal justice response is the most frequent form

of intervention. But, since it is primarily reactive (i.e., post fire) in nature,

its deterrent value is dubious.

A brief review of investigative and prosecutive responses to arson demonstrates the difficulties inherent in designing more effective strategies to

combat this crime problem. To begin with, it is difficult to gauge the true

extent of arson because the fire's cause is often difficult to determine, and

many incendiary incidents are mistakenly labeled as suspicious, unknown, or of

accidental origin. Estimates of the actual incidence of arson fires range from

3 twenty-five to fifty percent of all fires. Where an incendiary cause is suspected, the shift in control of the fire scene from firefighters to fire or

police investigators can result in the loss of valuable time and in compromising

the integrity of the evidence at the scene.

Next, the transfer of the case from investigators to prosecutors often

results in diminished continuity. Most arson evidence is overwhelmingly circum4

stantial and in most cases implicates the suspect only indirectly. Because of

prosecutors' desire to maximize conviction rates, they have an understandable

aversion to new or troublesome kinds of cases. Consequently, prosecutors have

been reported to avoid arson cases and to discourage investigators from pursuing

5

them effectively. This in turn generates an understandable reluctance on the

part of investigators to try to interest a prosecutor the next time an arson case

develops. Consequently, many investigations languish for lack of momentum.

Overall .these impediments to enforcement have a debilitating affect on investigator

morale, which serves to undercut the rate of progress essential in arson investigations.

Suspects who commit arson out of emotional impulses such as revenge and

pyromania appear to be those most likely to be caught, for the irrationality of

46
their actions diminishes caution and increases the likelihood that they will

leave behind incriminating evidence. For this reason, those who commit arson

out of strong emotional stimuli tend to be overly represented in arson arrest

and conviction statistics, while those who commit arson in a calculated and

planned manner stand to gain a de facto type of "informal immunity" as a result

of their ability to destroy or conceal evidence. Thus, the low arrest and even

lower conviction rates for arson substantially dilute the deterrent power of the

criminal sanction.^

Despite lingering questions about the impact of punitive sanctions, local

public officials have focused on prosecution and punishment as the most potent

deterrents. Two implications follow from this view. First, a broad range of

non-criminal justice prevention or early intervention strategies may either be

ruled out prematurely or identified too late to arrest a developing arson epidemic.

Second, strong reliance on criminal santions places considerable pressure on

investigators and prosecutors to "solve" arson cases and "punish" arsonists. Both

the pressure and the official response interact in a political environment which

focuses on those offenses that are most readily subject to solution. As noted

above, in cases of arson the most vulnerable population of offenders is likely to

consist of persons are emotionally motivated.

Focusing on Arson Through a "Motive-based" Strategy

To summarize the foregoing discussion, a primary reason for the difficulty

of enforcement agencies in combatting increases in arson is the highly reactive nature

of the law enforcement response. Traditionally, the objective of investigators

and prosecutors has been the arrest and conviction of persons who commit arson,

rather than some form of intervention to prevent future criminal acts. Since

relatively few arsonists are caught, and still fewer are convicted, the threat of

punishment is arguably not a very effective deterrent in this case, nor in

47
combatting most other forms of crime.

Early Warning Signs and Early Intervention Strategies

The most frequently cited motives for committing arson are revenge, pyromania

vandalism, concealment of another crime, intimidation, and arson-for-profi t. In

many cases, decisions to commit an incendiary act will be so impulsive--and therefo

unplanned--that the potential firesetters generate few noticeable warning signs

of criminal intent. For example, a family dispute may escalate so rapidly to an

act of arson that no one could have foreseen or forestalled the oncoming tragedy.

Unanticipated fi resetting may also stem from erratic or irrational behavior of

disturbed or psychotic persons. Conversely, arson for other motives such as

profit is usually planned in a rational manner over a relatively longer period

of time, and although executed in stealth often follows a known pattern that

permits trained investigators to detect the crime.

If arson motives are arranged along a continuum which ranges from "rational"

to "irrational," then arson for profit should be posted near the former, with

revenge near the latter, and other motives falling between. If a second vertical

dimension is added (see Figure II) which arranges the motives according to numbers

of prior warning signs, then motives can be further distinguished according to

their susceptibility to early intervention. For example, several prior warning

signs of revenge arson may exist, manifested in earlier disputes ranging from

moderately noisy to extremely violent.'7 The problem posed by revenge arson

however, is the absence of an effective monitoring apparatus to deter, and notify

authorities when early warning signs are observed. Usually, neither the disputants nor witnesses, nor even experts, can as yet distinguish between conflicts

that will escalate into violent acts and those which will dissipate with the

passage of time. Although obviously desirable, intervention to stem the rise in

arson is still in its earliest stages and a long way from realization.

48
J3

05

c"

ELHo

05

c"

05 >

05O = o<

CD

CO

49
FIGURE II Arson Prevention:

Early Warning Sians

MANY

ARSON-FOR-PROFIT

RATIONAL

CONCEALMENT

REVENGE

IRRATIONAL

MOTIVE

IN TIMIDA TION

VANDALISM

MOTIVE

PSYCHOTIC

NONE

50
In order to examine the range of arson motives from rational, to mixed, to

irrational, it is instructive to use the notion of "moral hazard" as it may

be applied to arson. A term drawn principally from the insurance lexicon, moral

hazard refers to specific factors in the decision processes of an individual

that identifies him/her as arson-prone, and therefore an imprudent risk to an

insurer. When applied to arson motives there are psychological, social, and

economic pressures which weigh, for example, on pyromaniacs, revenge arsonists,

and those who commit arson for monetary gain. The interplay of psychological

and perhaps social stresses are far more significant, if less subject to detection,

in the case of the revenge arsonist. In contrast, economic stress factors are

salient with respect to the profit-motivated arsonist. The distinction between

these two types of moral hazard, however, lies in the presence of identifiable

and easily traceable indicators of the antecedent stress situations influencing

the potential arsonist. The indicators of prior stress factors left by the

revenge arsonist are, in most instances, clear and identifiable after the fact.

But only a small proportion of cases that possess these characteristics actually

result in the commission of a crime, and the detection of relevent factors prior

to a crime would require the establishment of a surveillance system so pervasive

that it would present a civil liberties problem of enormous magnitude. Even then

it would still be necessary to identify which of the arson prone people would

actually commit the crime.

In the case of arson-for-profi t, the issues are markedly different. The

pressures which weigh on the arsonist, and his/her preparation for the arson,

leave two converging trails; (1) financial stress indicators, and (2) pre-arson

planning steps. Although these factors affect the condition of the arsonist's

moral hazard, the emphasis here is largely on economic components because the

general indicators of financial stress (such as business recession or impending

bankruptcy), and their affect on local economies, can be identified and measured

with a moderate degree of accuracy.

51
In sum, economic stress situations profoundly affect the condition of moral

hazard. For arson prevention purposes therefore, it would be ideal to be able

to identify three categories of information, each with its own predictive

capabilities:

t Situation-based information, to focus on variable impacts

of economic conditions on different business sectors

(e.g., restaurants, home building, furniture, etc.)

t Location-based information, to focus on various types of

buildings (e.g. , schools, single-family and multi-family

housing, etc.) which are probable arson targets.

• People-based information, to focus on individuals whose index

of moral hazard indicated that they would be likely to commit

(or cause to be committed) an act of arson.

Each of the seven Arson Information Management Systems (AIMS), supported by

the U.S. Fire Administration addresses one or more of the above categories of

information. In most cases, the projects deal with arson for profit, because of

the presence of prior warning signs and the frequent rationality of the perpetrators.

Certain AIM systems are purely preventive in nature. They seek to identify

financial stress and other causal factors early enough to enable official intervention to prevent arson. Other AIM systems analyze information on multiple prior

fires and involved individuals, in the hope of determining whether groups of

people have conspired to set or to arrange to set fires. The following discussion

covers three representatives of the seven AIM systems that have established

methods of information gathering, analysis, and dissemination. The three cities

in which these systems are located are New Haven, Boston, and Phoenix.

There are several general similarities among the systems. They all use electronic data processing equipment, to some extent, in order to expedite the collection and analysis of fire and arson-related information. All three employ some form

of statistical or other type of information analysis to determine the correlation

between arson fires and other variables. Arson prevention measures are outlined

in each of the three jurisdictions based on the use of the arson information once

it is obtained.

52
Despite these similarities, the three AIM systems represent a range of

available options that can be used to determine the most aooropriate system

for a specific jurisdiction. For example, the Phoenix system is based on a

reactive strategy: the arson prevention measures designed for that jurisdiction

come from post-fire incidence reports. The other jurisdictions, on the other

hand, have developed preventive early warning systems used primarily to target

pre-arson building risks.

The early warning systems in New Haven and Boston rely on a mixture of

manual and electronic data processing systems. They have attempted to implement,

gradually, the electronic data processing aspects of their AIM systems in order

to facilitate the changeover from manual systems. The greater complexity of the

system in each of these three cities compared to the one in Phoenix offers them

a highly versatile and potentially more effective arson prevention system.

I. New Haven Arson Warning and Prevention System (AWPS)

A. Purpose of the System

The primary purpose of the New Haven model is to prevent arson from ocurring

by identifying those buildings most arson-prone in the near future. The intention

of the program is to spur preventive measures by members of the public and orivate

sectors. These include: (1) city officials (e.q. , to increase housina and building

code enforcement); {?.) law enforcement aqencies (e.g., to increase arson patrols in

"at-risk" areas); (3) insurance companies (e.g., to monitor increases in insurance

coveraoe); and (4) financial institutions (e.g., to consider risk information when

making loan decisions). In addition, the information provided by the early warning

system is also useful in post-fire investigations. Such latter uses include: distingis also useful in post-fire investigations. Such latter uses include: distinguishing common characteristics in arson fires, identifying the public adjusters

and insurers frequently involved with policyholders who suffer arson losses, and

obtaining information on property history.

53
B. How the New Haven AWPS Works

The arson warning system is based on the premise that a certain set of

"events" (independent variables) is closely associated with an arson fire,

(dependent variable). To determine which independent variables would be the best

predictors of future arson fires, the New Haven analysts examined historical data

for a five-year period. The first step in this process involved obtaining

information on arson fires that took place between January 1973 and September

1978 using these criteria:

e All structural fires occurring between January 1973 and September

1978 in occupied buildings where there was a monetary loss and the cause of the fire was listed as suspicious, incendiary, vandalism,

or reckless burning;

• All structural fires in vacant buildings regardless of loss or cause;

and

• All structural fires in occupied buildings where there was a monetary

loss and the cause was listed as "undetermined." These incidents were reexamined to decide whether the cause of the fire was, in fact,

suspicious. A limited number of these were included in the list.

The product of this information gathering process was a list of 1,432 structural fires, identified by street address. In order to compile a list of dependent

variables, a random sample of 110 was chosen for the actual analysis. In addition,

there was the corresponding selection of a control group from fire records of

buildings which had not sustained a suspicious fire during the 1973-1978 time

period. Buildings in this control group were selected by matching their characteristics with the experimental group on such features as use, size, construction

material, and number of dwelling units. This selection process involved on-site

visits as well as the study of local files.

The next step involved the selection of the various independent variables to

be analyzed statistically vis-a-vis the dependent variable. The original list

of variables included over 200 possible specific items in a wide range of categories,

Information was collected from the city building department, clerk's office, tax

54
collector's office, fire department, housing conservation and code enforcement

agency, and police department.

For each structural fire in the sample and for each control group item, the

information regarding the various independent variables was gathered, coded on

worksheets, and then keypunched and verified. A statistical package called SAS

(Statistical Analysis Systems) was used to determine the correlation between the

various independent variables and the arson fires. Through the use of frequency

procedures and a statistical regression model, the variable list was ultimately

reduced to four key indicators or "trigger" variables:

t Total amount and number of years of tax arrearage,

• Previous structural fires,

• Housing code violations cited by the New Haven Housing Conservation

and Code Enforcement Agency, and

• Liens and other claims on the property.

Statistical analysis revealed that 78 percent of the variance in arson

incidence between the structural fire group and the control group could be

explained by these four variables.

Having determined the "trigger" varibles for an arson prediction system, the

New Haven staff has mounted a program to test the findings. A decision was made

to collect a two-year back history on each of the four trigger variables.

Information on structural fires, tax arrearages, housing code violations, and

liens which occurred or were issued in New Haven between January 1, 1977, and

December 30, 1979, was collected. This work was executed manually utilizing offduty firefighters, student interns, and the AWPS staff.

Once collected, the information was recorded and stored by address, on color

coded index cards. The cards were arranged alphabetically, and a master list of

each address and the trigger variables which are now available. These lists form

the basis of the at-risk group.

55
Buildings which indicate the presence of all four trigger variables are "red

flagged" for immediate arson prevention intervention by the AWPS staff. In addition

buildings with three trigger variables are flagged for less urgent intervention.

Additional information on "red-flagged", or at-risk buildings was obtained on

assessed value, insurance coverage, physical description of the property, and

mortgage data. Thus, a great deal of information was consulted and analyzed by

the AWPS staff prior to the actual contact with the owner of the building.

C. Testing, Implementation, and Evaluation

The New Haven early warning system has completed testing of the "trigger"

variables. Implementation of the model and its preventive measures began in

March, 1980. An important part of the evaluation of the system has involved the

determination of the degree to which the various organizations receiving the "atrisk" information act on it to reduce the incidence of arson.

D. Resources Required

1. Staffing . Responsibility for design of the early warning system was

given to the Director of Planning and Information Services in the New Haven Fire

Department and to a civilian coordinator specifically hired for this purpose. To

collect the extensive amount of information regarding building history and financial

characteristics, four firefighters from the New Haven Fire Department were hired

for ten hours per week during their off-duty hours to collect the information

from various city agencies. In addition, several student interns from nearby

colleges helped with the data collection as part of the city's intern program.

The information on the "trigger" variables was collected by seven firefighters

hired on part-time basis during off-duty hours. The number of data researchers

required will be reduced as the manual collection of data diminishes. AWPS staff

presently includes a program coordinator, a housing rehabilitation specialist,

an adminstrati ve assistant, and a secretary. Future staff plans include a fulltime AWPS insurance adjuster and a part-time computer programmer/statistician.

56

i

•

i
2. Equipment . The statistical analyses performed by the AWPS staff required

the use of a computer. Keypunching and data processing facilities at the Yale

University Computer Center were utilized. The availability of the SAS packaged

computer program was also necessary for the statistical analyses.

3. Funding . The development of the original design and data collection of

the system was completed under a $10,000 award from the Factory Mutual System.

The testing phase of the program was funded by the U.S. Fire Administration and

the implementation phase by the Aetna Life and Casualty Company.

4. Access to Essential Records . Other types of resources required to

design, test, and implement the early warning system include the various records

held by public agencies or private organizations.

In the New Haven model, the following categories of information were collected

for the initial analysis:

Source

Building Department

City and Town Clerk

Collector of Taxes

Fire Deparement

Housing Conservation

and Code Enforcement Agency

Police Department

Type of Record

--Building code violations and

abatements

—Record of building inspections

--Demolition information

--Record of building permits issued

--Transfers of property

--Type of conveyances

--Liens on property

--Total amount of tax arrearage

—Number of years in arrears —Address where tax bills are sent

--All structural fire responses

--Use and occupancy of structures

at time of fire

—Situation found at fire —Ignition factor at fire

--Property damage loss from fire

—Fire code violations and

abatements

--Housing code violations and

--All police responses

57
II. Boston: Arson Early Warning System (AEWS)

A. Background

The Boston AEW System was developed following an investigation into an

organized arson ring which operated in the Symphony Road area of that city. The

ring was involved in setting dozens of fires during the period 1974 to 1977.

Following the deaths of several tenants in arson fires within a short time, the

residents formed a group (Symphony Tenants Organizing Project) to combat the

problem. The symphony Road group felt that a prediction system could be created

to prevent arson because buildings that were ignited had similar characteristics.

A decision was made to undertake a pilot study, conducted by Urban Educational

Systems, Inc. (UES), of Boston, a firm created for the purpose of conducting

arson research. UES received a grant from the U.S. Fire Administration to develop

an arson early warning system. Three manuals have been produced by UES growing

out of their work on this Droject. These manuals Dublished by UES in 1979 and

available from them, are: (1) Arson Action Guide , (2) Research: A Manual for

Arson Analysis and Property Research , and (3) Tools: Anti-Arson Programs and

Legislation .

B. Purpose of the System

The arson prediction system is utilized to identify buildings that are most

prone to arson fires. This information is used to initiate a variety of arson

preventive measures such as enforcement of building codes, reduction in overinsurance of property, promotion of neighborhood awareness, and proactive

investigation by law enforcement agencies.

As in the New Haven AIM system, the Boston AEWS serves as both a data

collection system and an arson prediction system. Information from city agencies

on building or owner characteristics can be collected and made accessible in an

efficient manner. This will aid in the investigation and prosecution efforts in

post-fire search for evidence, in the event that arson is not prevented.

58
C. How the System Works

The AEWS study selected 78 residential, absentee-owned, multi-unit rental

buildings in the Boston area in which a fire had occured between June 1, 1978 and

May 31, 1979 as their sample population. To meet the criteria, the fire had to

have caused a loss of more than $500 and had to be classified as incendiary, suspicious, or one that caused abandonment. The 78 sample buildings were matched

with a control sample of 78 buildings in which there had been no fire in the

same time period.

Historical differences between these two groups over a 10-year period were

determined on the basis of information on over 300 variables collected for each

building.

Results from the analysis suggest that combinations of as many as a dozen

variables will constitute the best indicators of high arson risk. Variables can

be assigned relative weights depending on their correlation with past arson fires.

The variables examined are divided into two categories: (1) economic

stress factors of the building, include such items as: vacancy rates, debt-to

equity ratio, sale and resale transactions, previous fire record, building code

violations, santiary code violations, tax arrearage, liens, attachments, rent

control data, and time lag between building citations and repairs; and (2) the

owner's characteristics include such factors as: previous fire record, owner's

other property, and the owner's financial status. In many cases a distinct

separation between economic stress factors and owner-characteristic factors is

not possible. For example, code violations and tax arrearage bear on both.

D. Implementation, Testing, and Evaluation

The process of collecting the building and ownership information has been

completed.

E. Resources Required

1. Staff and Equipment . The staffing required for this study is provided

59
by Urban Educational Systems, Inc. Three full time equivalent staff members have

been assigned to the AEWS study, including two computer specialists (one fulltime, one half-time), one researcher, and an administrative assistant (half-time).

2. Funding . Funding for the AEWS study was provided by a grant of $200,000

made to UES by the U.S. Fire Administration. Approximately one-half of this grant

is devoted to research purposes, and the other half to providing technical

assistance to other communities throughout the nation.

III. Phoenix; Arson Prevention and Analysis Unit (APAU )

A. Background

The Phoenix program is managed by the Arson Prevention and Analysis Unit

(APAU) in the Phoenix Fire Department. Data located and analyzed in separate

local agencies will be collected and studied by the Arson Prevention and Analysis

Project.

The APAU project serves three general purposes:

(1) Output from the analysis of data is distributed to local agencies, thus

providing each with information generated by the others.

(2) The data analysis indicates patterns of arson incidence in the Phoenix

area which can facilitate deployment of arson investigative personnel.

(3) Information provided through the data analysis assists in joint planning

of strategies among the various Phoenix agencies, including the police and fire

departments, insurance companies, county prosecutor's office, the arson task

force, city manager's office, city council, the chamber of commerce, and other

civic groups.

B. How the System Works

The Phoenix AIMS staff has developed special record-keeping forms for arson

investigations undertaken in the city. Arson investigations in Phoenix are

conducted by the Fire Department (Fire Investigation Squad) and the Police

Department (Bomb and Arson Squad). Both units are provided with the improved

60
data collection forms. These forms can be used to establish several files including an "Arson Location" file, a" "A~son Suspect/Victim Investigation Lead"

file, a "Property Management" file, and a "Fire Dollar Loss Reported" file.

Additional information is collected from various insurance companies, from the

Property Insurance Loss Register (PILR), and from other city departments including

Zoning, Parks and Recreation, and Public Housing.

The information received from these sources can be programmed, coded, and

entered into a work processor to allow rapid retrieval of requested information.

Multiple listed information (e.g., an owner's name under "previous fires,"

"housing code violations" and "insurance claim files"). Unlike the New Haven and

Boston AIM systems, the Phoenix model does not attempt to predict the risk level

of specific owners or buildings, but instead focuses on geographic areas.

C. Implementation and Evaluation

The output of the Phoenix AIM system is distributed to a wide range of

potential users. Police and fire units utilize if for- arson investigations (e.g.

intelligence operations, surveillance decisions, property loss information

retrieval, etc.). The local Arson Task Force uses the information as a basis

for community outreach programs, legislative lobbying efforts, and as a means of

informing the media. Other recipients of the output include, when appropriate,

insurance companies, civic groups, the city council and mayor's office, and other

law enforcement agencies.

D. Resources Required

1. Staffing. Staff are drawn from existing personnel in the Fire Department

Arson Investigation Unit and Police Department Bomb and Arson Squad. Operation

of the AIM system is handled by a Loss Prevention Analyst in the Arson Prevention

and Analysis Unit.

2. Funding . The project has been funded by a U.S. Fire Administration

grant of $20,000, which is used to support the Lost Prevention Analyst.

61
3. Equipment . The word processor and other equipment necessary for the

information analysis are supplied by the Arson Investigation Unit of the Fire

Department.

Conclusion

The above discussion focused on those aspects of arson motives that render

certain motive patterns (and principally arson-for-profit) more susceptible to

prediction and early intervention than others. A most important finding that

emerges from a review of current arson control programs is that the number of

indicators of prior intent to commit arson, rather than the rationality or

irrationality of each motive, provides officials with arson reduction opportunities that are just becoming appreciated. Arson-for-profit is believed to constitute the most costly motive, in that perpetrators routinely cause the

widespread destruction which they have planned. The discernible motive

pattern for this profit-motivated crime provides officials who are willing

to probe for background information on the financial distress that often can

be traced to distinct pre-arson planning steps, and frequently culminates in

arson. Consequently, it is likely that future arson control demonstration

programs will focus on profit-motivated arson. The considerable potential

to prevent acts of arson committed for other more irrational motives such as

revenge, remains to be tested.

62
ENDNOTES

1/ - John F. Boudreau, et a"!., Arson and Arso n Inv estigation: Survey and Assessmcn

(Washington: U.S. Government Printing Office, 1977~T; National Fire Prevention and

Control Administration, Arson: Amer ica's Malignant Crime (Washington: National F Prevention and Control Administration, 1976); U.S. General Accounting Office, Repoi

to Senator Charles Percy, "Federal Authority and Coordination for Arson-Related

Crimes". No.B-171019 (Washington: Contoller General of the U.S., 1978); Internatit

Training, Research, and Evaluation Council, Workshop-Synopsis: N ew York Governor '. Conferenc e on A rs on and Arson-for-Prof i

t

(Fairfax, Virginia: ITREC, 1978];

Nicholas Borg and Leonard David, Arson: A Multi-Dimensional Problem (Boston:

Society of Fire Protection Engineers, 1976).

2/ See Boudreau, supra, note 1, pp. 19-27; R. G. Vreeland and M. B. Waller,

The Psychology of Firesettinq: A R eview and Ap praisal , Report No. NBS-GCR-79-157

TWashington: National Bureau of Standards, 1 979) , and Bernard Levin, "psychological Characteristics of Fi resetters ," in Fire Journal , March, 1976.

3/ Boudreau, supra , note 1, p. 1.

4/ Note. "Arson Fraud: Criminal Prosecution and Insurance Law. Fordham

Urban Law Journal , 3 (19791.

5/ See Dale Tooley and Christopher Munch, "The Need for Prosecutor Involvement

in Arson Cases," Firehouse Magazine , August, 1979. Mr-. Tooley is the District

Attorney in Denver, Colorado.

6/ See Boudreau, supra , note 1, pp. 29-31; and Robert McGann, "DA's are Urged to Become Involved in Early Stage of Fire Investigations," in Fire

Engineering , August, 1978.

7/ See Marie Wilt and James Bannon, Domestic Violence and the Police (Washington

Police Foundation, 1977); and Morton Bard, Family Crisis Intervention: From

Concept to Implementation (Washington: Government Printing Office, 1973).

63
INCENDIARY FIRES IN JAPAN

by Tetsuhiko Kawamura

Japanese Assocition of

Fire Science and Engineering

Incendiary Fires in Japan Today

Arson has been thought a rural type of offense until rather

recently. There are as many arson fires in rural areas as urban

areas when compared with the number of occurrences per population

of the areas. It has also been said that since the beginning of

this century, arson has been on the decrease except in the periods

of depression.

However, this tendency has recently been changed a little and

in cities, especially in Tokyo, Osaka and in other big cities arson

has exceeded the fires with other causes. But when looking at the

whole country, from the classification as shown in the Fire Journal,

March 1976, arson occupies not the top place but the fourth, both in

number of and loss by fires, as shown in Figs. 1 and 2.

Incidentally, little change has been found in the number of fires

and amount of loss in Japan for the last few years. In 1978 Japan

experienced 70,423 fires and loss of ¥130,539 million (approximately

$593 million).

Types of Incendiaries

Most malicious fires are started by individuals in secret. Many

fires are started for reason of revenge or spite, which are brought

about by the feud between relatives, neighbors, or other acquaintances.

Some fires are caused by persons who have a sort of enmity against

society, or by pyromaniacs whose motive is to obtain a sort of satisfaction from the fire and the accompanying events. Other types of

firesetters include thieves who want to destroy evidence or who start

fires because of dissatisfaction over their spoils. And it is remarkable

that many fires are caused by incendiaries committing suicide nowadays

by setting fire to the fuel gas leaked intentionally or such flammable

liquids as gasoline or kerosene. But incendiary fires motivated by

"defrauding insurance companies" are very few as shown in the reports

by Yamaoka and Murakami.

64
What Insurance Companies Do to Prevent Fraud by Arson

As mentioned above, there are very few cases of arson for the

purpose of insurance fraud in Japan. Insurance companies have established

organizations some years ago to investigate suspicious cases related to

insurance fraud, but almost all the cases are related to automobile

insurance, whereas very few cases are involved in fire insurance — one

or two cases in a year.

Early in the sixties, we had several remarkable arson fraud cases —

rubber-shoe manufacturers in Osaka, textile wholesaler in Kyushu. Since

then insurance companies have exchanged information with each other,

making their underwriting more cautious.

Summary

Except in Tokyo and other big cities, incendiarism is not taken as

a very grave problem today in Japan. And even insurance companies do not

pay much attention to it. There may be many reasons for this situation.

The fact that economic conditions as a whole are not so bad may be cited

as one of them, traditionally strong guilt feelings against playing with

fire can be a second force to prevent the increase of incendiaries, the

high percentage of arsonist apprehension, which exceeds 30%, may be

another factor. And the fact that Japan is ethnically an almost uniform

nation and consists of a very stable society is one of the effective

factors, I should say.

Although these are the incendiary situations as of today in Japan,

the following two facts are to be noted:

(1) Repetitive or serial incendiary fires by arsonists, who

are often mental defectives or people with low intelligence, are caused from time to time in big cities, more

often in larger cities.

(2) Incendiary fires or sometimes explosions which are caused

by firesetters who want to commit suicide setting fire to

fuel gas intentionally leaked by them, or flammable liquids

such as gasoline and kerosene. There were 531 such people

who committed suicide in 1978, and in the case of leaked

gas, these incidents tend to cause damage to other people

and property, in such a densely built-up area as Tokyo.

65
CCA USE)

TRASH

BURNINGr

HEATINGrZ COOKINfy

EQUIPMENT

SMOKINGRELATED

incendiary

or suspicious

ELECmtCAk

UNKNOWN

CAUSES

5369 me$

TOTAL FIRES

To & 20 25 mm

(PERCENTAGES)

Frg 1 forctnt of ffres fy cause , I97S

UAUSE)

HEATlNGrt CQOKINQ

EQUIPMENT

SMOKim

RELATED

TRASH

BURNING

INCENDIARY

OR SUSPICIOUS

ELECTRICAL

UNKNOWN

CAUSES

TOTAL LOSS

^93.000TM

*32J!50TH

20 % 60 80 100 120 IW 160 ISO 200

(DOLLAR LOSS IN THOUSANDS)

FtjZ Dollar loss from, fires , 1918

66
Discussion of Presentations on Arson

Karchmer Presentation

Handa: You mentioned several cities. I wonder whether the pattern

of each jurisdiction varies according to the city.

Karchmer: Each of the four cities I reported on had different types

of arson problems. New York and Boston were primarily multi-family

residential housing. New Haven was primarily single-family housing.

Arson for profit is a problem in both these cities. Phoenix was single-family housing with commercial arson as a problem. So, you

have at least three different kinds of arson problems to which these

AIMS systems were a response.

Furthermore, the New York and New Haven multi-family housing

was "absentee" owned by absentee landlords. That gives us a further

difference among the different programs.

All four AIMS projects are currently working on refining their

output and figuring ways to utilize that information. The issue of

the impact of its evaluated information is forthcoming, but is several

months away.

Handa: When business is bad and/or there is a death, is this one indication of motivation for arson?

Karchmer: Yes, let me explain. A study was done several years ago

that is reported in the Journal of Insurance. Between 50 and 75

variables were analyzed to determine what would predict deaths of

increases in arson in the U.S. Data from the U.S. Department of

Commerce and its various reports were utilized. The one variable

that correlated most closely with the increase in arson, was non- personal bankruptcy which included several different kinds of

bankruptcy under our laws: partnership, corporateship , as well as corporateship reorganization. But the real value of the information

is that bankruptcy and arson statistics so closely followed each other.

The problem with predicting commercial arson which includes industrial

arson, in contrast to residential arson, is that the indicators of

residential arson all come from public sources of information: liens,

code violations, firefighters. The comparable stress indicators for

commerical or industrial arson are found in the business 's financial

books, its tax receipts and other private nonpublic sources of information. This means that it is next to impossible for a researcher to use related financial stress information to attack commercial arson.

67
The indicators of commerical arson, therefore, are most useful

as indication of criminal intent. For example, insurance may be

increased drastically on the premises just prior to the fire. In many

states it is possible to obtain that information. Secondly, there may

be changes in inventory levels in that company; such that cheap

inventory is substituted for expensive inventory prior to the fire.

In some cases, it is easy for an investigator to get that kind of

circumstantial evidence of a likely involvement of an owner in the arson. But it is difficult to prove the involvement.

Apart from that, the intervention strategies to combat commercial arson deal with the development of criminal intelligence programs to

gather criminal information about the kinds of people the business

owner may be dealing with, and they are very different from the

statistical and other kinds of records upon which the AIMS projects

are based.

I have just completed an enforcement manual on arson for profit

for the Justice Department which details that type of a program. I would be happy to provide those who are interested in receiving a copy. It is much better to do that than raise the discussion here.

Handa: Can you include the information of explosives used in arson

cases for revenge?

Karchmer: Presently apart from location and time of day, I do not

believe any other kind of information is gathered by any of the seven AIMS systems which would help in predicting revenge arson.

Kawamura: I am interested in any figures and/or statistics. What

is the rate of arresting arsonists? How many of them are convicted

from trials?

Karchmer: I do not have that information. The personnel who work in

these AIMS systems developed better case tracking mechanisms. I can provide you with the names and addresses of those people and they can provide you that information.

68
Kawamura Presentation

Levine: Did you say that all fires in Tokyo are investigated?

Kawamura: We do investigate as many as possible, but the data in which

we understand the motive of arson clearly are used in my Figure 1.

Levine: Can you investigate all fires, not just arson?

Kawamura: Not all of them.

Levine: That is a very important factor in this country. Those

cities which do little investigating of fires, do not report much

arson. The fires you describe as unknown causes, are about 15%

of the fires. Is there a reason that the fires of unknown causes have a much larger than 15% portion of the loss in yen?

Kawamura: We regret that we have no answer to this question. The

data in this figure are based on the entire country, not just Tokyo.

Clarke: I'm amazed at the remarkably small number of cases to defraud

insurance companies in Japan, as compared to the very large number in

the United States. My question is whether a large fraction of com- mercial property in Japan is covered by casualty insurance? In the

United States virtually all commercial property is covered by

insurance.

Kawamura: It is true that people in Japan are less insurance minded

than in U.S., but almost all commercial properties in Japan are covered by insurance. The percentage of dwellings covered by insurance

is not as large as U.S.

Miyama: With respect to Figure 2, please explain why money for

unknown causes is high. In Japan, persons who cause accidental fire can be criminally penalized.

Kawamura: I think that is not true. Person who pays damage does

not get penalized. However, business people who are in charge, (i.e.,

maintenance or building guards) if proven negligence on their part,

would be criminally charged.

The legal point of view is described above, but traditionally

there might be penalty from society.

Karchmer: In some cities one of the arson for profit problems involves

a building that is profitable that is destroyed for the purpose of

creating an even more profitable business on that location (some

types of urban renewal or urban development) . Do you have anything

comparable to that?

69
Kawamura: More specifically, do you mean to cause arson to make

profit in specified development area after demolition of the old site?

Karchmer: Yes, exactly.

Kawamura: There is no criminal penalty on hospitals. However if

patients are hurt or die during the fire, the hospital can be penalized

for their negligence in not taking care of their patients.

Handa: I should like to speak concerning the number of cases of

unknown causes. Sometimes the agencies are unable to handle responsibility for all cases. For convenience, they are classified as unknown

causes without detailed investigation. I've found this to be true

when I was asked to be a legal adviser.

Levine: A note of interest, for four years we've had a program

at Johns Hopkins University to investigate the causes of all deaths in

fires in the state of Maryland. During that time about 3% of the

people killed in fires were killed by self immolation, by pouring gasoline over themselves. If we use that same percentage for the 8,000

people in this country who are killed every year in fires, that would

be about 240 people which is not all that different from your statistics

on suicide. Perhaps it is a little lower.

Kawamura: I think that the percentage of suicide arson in Japan

is high, because total number of people who died in fire is a little

less than 2000 and the number of people who died in suicide arson is

about 530.

70
TOXICITY OF COMBUSTION PRODUCTS

71
BASIC CONCEPT OF TOXIC HAZARDS

IN BUILDING FIRES

by

Koichi Kishitani, Dr. Eng., Prof,

Fumiharu Saito, Dr. Eng.

Shyuitsu Yusa, Dr. Eng.

72
1. Introduction

Losses due to fire may be divided into material damage

and human losses. It may be said that material damage is

caused by heat and human losses by smoke and gas.

Consequently, with respect to fire protection measures,

the procedures of research will be dissimilar since there

are great differences between measures against heat which

cause structural damage to buildings and safety measures for

occupants of buildings in connection with the principal

factors causing damage and the concepts in making evaluations.

The first matter to be taken up usually when discussing

measures to secure safety of human lives during fire is the

problem of- smoke and gas, and there is not much said concerning heat. This is because loss of human life attributed

to heat is due to burns as seen from fire statistics, and

countermeasures are heavily dependent on compartmentation

of fire and fire fighting activities.

In contrast, measures against smoke and gas in building

fires must be discussed based on the relations of the flow

characteristics of heat, smoke and gas from the room on fire

to the various parts of the building, the varieties and

quantities of the components emitting the above, and the

corresponding activities of humans. Obstructions to human

behavior must be considered first of all from the standpoint

of physiological obstructions. Accordingly, as impeding

73
factors, the types and quantities of combustion gases, the

thickness and humidity of smoke, and further, although

perhaps not of a degree to cause burns, the rise in atmospheric temperature must be taken into consideration.

In other words, whereas many research works have been

only on compositions of gases in studies of gas toxicity,

for the problem of toxic hazards in fire, examinations must

be made not only of gas, but all combustion products including the entire lot of factors mentioned above.

The varieties and quantities of combustion products

will differ according to the correlations between the

varieties and quantities of materials burned and the conditions of the building, namely, the thermal properties and

geometrical sizes of constituent materials, ventilation, etc.

of the space on fire or in combustion.

Further, the method of evaluation and the level of

safety indicated will differ greatly depending on whether

toxicities of combustion products are to be evaluated as

acute or chronic, and still further, whether the toxicities

are to be evaluated on the basis of absolute or relative

degree

.

These interrelations and the governing factors are

shown in summarized form in Fig. 1.

That is, for acute toxicity, it is possible for the

limit to evacuation activity according to one's own will or

74
physiological death to be made the basis for evaluation, but

for chronic toxicity, it is necessary to consider a range

from a degree that light activity is possible to that where

the person will become a human vegetable due to complete

functional impediment.

With regard to the former in this case, It is possible

to proceed with research by animal experiments, but for the

latter, it will be unavoidable to rely on chemical analysis

employing instruments.

For evaluation of toxicity by chemical analysis, there

will be the extremely complex problem of making detailed

studies of progress made in analytical techniques and of the

type of gas and the degree of trouble, and further, establishment of a plural number of mixed gas toxicity evaluation

formulae

Meanwhile, there are large amounts of high-polymer

materials being used in the forms of building materials,

furniture and daily necessities, and it is surmised that the

toxicity of gases is greatly increased by combustion of these

materials

It must be considered that it will be too late to establish a measure against gas waiting for research on toxicity

which includes chronic toxicity to be completed.

In view of the above, it is necessary in coping with

actual situations for combustion conditions to be those

75
under which prediction of combustion properties of materials

in a real fire will be possible, and for an evaluation method

considering acute toxicity to be established.

2. Analyses of Full-Size Fire Experiments

For evaluation of gas toxicity of a material, it is

necessary to be able to predict the combustion products to

be emitted by that material in a real fire, and for that

purpose it is necessary to set the conditions of heating to

which the material will be subjected in a real fire.

However, since buildings are of various configurations

depending on their uses while at the same time manifold objects

are placed indoors, .although fires may be caused by combustion

of identical materials, the combustion products coming from

the fires must be considered to be of differing compositions.

Consequently, it may be expected that there will be many

combinations of temperatures and supply of air in combustion

in real fires. It is difficult, and unrealistic, to attempt

to evaluate toxicity by heating a. material subjected to these

many different combinations. Therefore, it will be necessary

to find basic combustion conditions under which gross errors

will not result in evaluation of the gas toxicity of a

material by analyzing in detail the properties during fire.

As a method of solving such a problem, it will be

useful to make detailed investigations of buildings after

fires, but it is difficult to estimate dynamic behayiors of

76
fires. Accordingly, it becomes necessary for fire experiments

to be carried out with buildings of actual size to accumulate

and analyze data,

Many fire experiments have been conducted in Japan with

the purposes being various studies regarding fire. The

objectives of- these fire experiments have differed according

to the needs of the time, but may be broadly divided into the

five categories below.

1. Hazard of spread of fire to neighboring

building

2. Compartmentation of fire

3. Room temperature and duration of fire

^ . Properties of room on fire

5- Generation and control of smoke and gas

These experiments were carried out to verify the many

laboratory and theoretical studies and to gain rough concepts

of fires, and there were not a few which led to development

of new research fields through analyses of experimental

results. Consequently, the purposes of fire experiments

have close relations with the trend of research on fire.

That is, in fire experiments at the initial stage, there

were many which had the objective of safety of structures of

buildings, but as buildings became taller, large underground

shopping areas were developed, and fire statistics were

analyzed, more and more experiments in which studies of

77
smoke generation and gas toxicity were added came to be conducted . There were experiments in which buildings were newly

constructed for the purpose of fire tests, but since these

required considerable testing expenses and labor, many of the

experiments were carried out on modifying parts of buildings

planned to be demolished. Consequently, the testing conditions did not coincide in many cases. The fire experiments

carried out in Japan up to this time which were concerned

with emission characteristics and toxicities of smoke and

gases are summarized in Table 1.

In these experiments, adequate measurements were made

on temperatures necessary for combustion conditions of

materials, but there were few in which measurements were made

of air supply which is an important factor in establishing

combustion conditions.

3. Hazards to Humans

3-1 Analysis of Victims of Fire

The classification of the present causes of fire fatalities in Japan today consists of carbon monoxide poisoning,

burns, contusions and bone fractures, unknown, other and

suicide"1"^. It is surmised that among those classified as

deaths due to burns, there was a good proportion consisting

of those who initially (principally) were victims of toxic

78
gases. Reports of. the results of investigations on degrees

of carbon monoxide-hemoglobin saturation in persons killed

2

in fire substantiate this . Many high polymer materials are located inside buildings

as interior finishing materials and articles ;accomodated , and

there is a possibility for gases of high toxicities .other

than carbon monoxide which are peculiar to these materials

to be emitted during fires.

As a result of investigating the degrees of CO-Hb

saturation and cyanide levels in serum of 30 cases of

fatalities in fire, it was reported that most of those killed

had cyanide in their blood, with some having reached minimum

lethal doses .

In the U.S.A. and elsewhere, the connections with alcohol

4) and illnesses have been pointed out and clinical studies

of casualties due to fire have become of increasing importance.

This is necessary also from the standpoint of studying unconfirmed toxic substances produced in decomposition and combustion of high polymer materials. It is regrettable that cases

of study regarding this are few in number in Japan because

of various restrictions.

3.2 Criteria for Evaluation

At the present stage, checks by animal experiments are

indispensable when examining combustion toxicity. The correlation between humans and test- animals ; and selection of the

79
kind of test animal are the problems in such case, In

studies made in the past, with regard at least to lethal

limits among physiological effects of toxic gases on various

test animals, classifications could be made according to

those for which the limit of lethal concentration rose with

increase in body-weight and those for which body-weight was

of no concern and a more or less constant level was indicated.

It may be said that the latter is more desirable from the

standpoint of handling in experiments.

With respect to selection of the kind of test animal, it

may be said that bigger animals would be suitable in case of

carrying out biological analyses in detail, but otherwise, it

may be said that small animals are desirable from the standpoints of availability, rearing and management, securing of

quantity, ease of handling, and number required for a single

test. At present, using mice and rats are mainstreams in

Japan and the U.S.A., respectively, and it is necessary at

least for the correlation between these two to be investigated.

Regarding evaluation of gas toxicity, there are the

problems of acute toxicity and chronic toxicity. In relation

to acute toxicity, it would suffice to consider impediment of

activity or fatality. In contrast, with regard to chronic

toxicity, further studies must be made on setting of period

of observation after exposure, items of observation after

exposure, and methods of observation.

80
In consideration of the above; it is thought suitable

for acute toxicity which considers observation for a short

period after exposure to be taken as the tentative criterion

for evaluation.

k. Method of Evaluating Gas Toxicity During Building Fire

4.1 Evaluations of Relative Degrees of Toxicity of Various

Materials

In Japan at present, the combustion toxicities of materials generally are being evaluated through relative comparisons.

The methods of evaluating toxicities of combustion products

may be broadly divided into evaluations by chemical analyses

of products and evaluations' by biological analyses using test

animals. The former have the advantage that combustion conditions can be readily set in large number, but problems

remain concerning appropriateness of overall evaluation and

oversights in detection of toxic components -With the latter,

there is the advantage that the physiological effects on

humans can be estimated to an extent by the "effects seen in

the test animals, but there is a slight drawback with respect

to reproducibility. From the standpoint of overall evalua^

tion it may be said animal tests are advantageous at present.

Evaluations using test animals may be broadly divided

into methods evaluating with sample weights and heated

surface areas constant and methods (LC 50 ) applying techniques

81
to determine median lethal doses (LD50). It will be necessary to select the toxicity evaluation method considering

2 and 3 previously described.

With the technological level presently available,

including combustion conditions and measures for evaluating

toxicity, the problem presently faced may be said to be how

an evaluation method on which a consensus can be reached

is to be decided.

k.2 Overall Toxicity Evaluation Based on Standard Materials

As stated up to this point, there remains a mountain of

problems which must be solved in order to establish an overall toxicity evaluation method which includes sure "safety."

In such circumstances, a method such as that indicated

below will be effective in getting close to "safety" by

the slightest degree.

There is a method where natural materials which have

been used by humans inside buildings for ages are considered

as standard materials (for example, of interior finishing

materials and materials accomodated indoors, wood among

board-like materials, and cotton among fibers), and it is

demanded that the combustion toxicities of the materials at

the least must not be more hazardous than the standard

materials. If still more "safety" is to be pursued, there

will be a method, for example, in which one half the toxicity

82
of a standard material is sought of other materials.

In order tc secure "safety." it is necessary for the gas

concentration in the building during fire to be grasped, the

interior finishing materials restricted ? and combustible

furniture and the like to be reduced for the allowable gas

concentration, but it will_ still be premature for a conclusion to be drawn at the present stage *

References

7 1) Fire Defense Agency, "Fire Defense White Paper, n1978.

2) T.. Yamada, et al., "Causes of Deaths in Fires,"

Fire Science Laboratory Report, No. 11, 197^.

3) M. Fukui , "Cyanide in Serum of Persons Killed in

Fires Assessed by the Quantitative Colorimetri.c Method,

Report of the National Research Institute of Police Science,

Vol. 22, No. 1, Mar, 1969.

H) Berl, W. G . , and Halpin, B. M. , "Human Fatalities

from Unwanted Fires," APL/JHU FPP TR 37, Dec'. 1978.

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87
PRELIMINARY COMPARISON OF COMBUSTION MODEL IN TOXICITY

TEST METHOD WITH A LARGE SCALE FIRE SCENARIO

by

M. Birky

1 .0 Introduction

The objective of the large scale fire studies was to determine if a correlation exists between the toxicity test method fire "model" and

"real" fires. The fire "model" used in the proposed combustion toxicity

test method consists of a cup furnace reported by Potts [1]. Toxicity

determinations on materials are made in a flaming and non-flaming mode

of operation to approximate a flaming fire and a smoldering fire.

Since each "real" or accidental fire is different, the scenario that

leads to the single largest number of fire fatalities was chosen for the

comparison studies. The scenario of choice is the cigarette ignition of

upholstered furniture and bedding [2]. This type of accidental ignition

results in smoldering (non-flaming) combustion of cotton and flexible

polyurethane foam as the primary materials used in these types of furnishings.

The proposed comparison or correlation parameters between the two experimental

procedures were chemical analysis and toxicological analysis of the

combustion products of a non-fire retarded, flexible polyurethane (GM-21

)

and cotton batting. The analytical comparison was based on the analysis

of carbon monoxide (CO), carbon dioxide (CO,,), total hydrocarbon (THC),

hydrogen cyanide (HCN), and "fingerprint" analysis of hydrocarbons.

Toxicological comparison was based on the exposure of rats to the products

from the two different scaled experiments.

2.0 Facilities and Sampling System

The facility for carrying out the smoldering combustion of these 2

materials is shown in Figure 1. Gas sampling ports for the chemical

analysis are designated as ports 'A'. The letter 'B' indicates the port

used for filling the animal exposure chamber used in the proposed standard

test method. Port 1 C is the return port from the animal chamber.

As noted in Figure 1 , the sample was placed on a load cell for weight

loss determinations. Weight loss information was used to determine mass loading of smoke for toxicity determinations and for comparison between

the 2 experimental procedures.

Figure 2 illustrates diagrammati cally the gas sampling system and animal

exposure system as interfaced to the large scale fire room.

88
3.0 Polyurethane Results

3.1 Analytical

A summary of the preliminary analysis of the various gas species for the

large scale experiments and the test protocol on flexible polyurethane

at various concentrations is shown in Table 1. As noted in the table

the HCN concentrations are higher in the large scale experiments by a factor of 2 or 3 depending on size of sample decomposed* However, from

a toxicological perspective this difference is not very significant

since the lethal level for HCN is about 200 ppm for a 30 minute exposure.

The THC (total hydrocarbon) concentrations are higher in the test protocol

system than in the self smoldering large scale tests (Table 1). However,

the "fingerprints" of the hydrocarbons as determined by gas chromatography

using a flame detector (FID) are nearly identical.

As noted in Table 1, the CO and CO2 concentrations are very similar in

the 2 sets of experiments.

3.2 Toxicological Comparison

The LCcq for this polyurethane foam in the non- flaming model as determined

by the test protocol is about 16 mg/1 . The deaths are not due to HCN or

CO. This fact was substantiated by environmental measurements of HCN,

CO, and blood chemistry. This conclusion is further verified by deaths that

occur 3 to 1 5 days post-exposure. The cause of the deaths in terms of

chemical species has not been identified. However, death is attributed

to lung damage due to a chemical irritant. TDI is a possible candidate.

Analytical measurements for TDI are in progress to confirm this hypothesis.

Exposure of animals to the products generated in the room by selfsmoldering combustion results in an LC 5Q of 35-40 mg/1. Death in this case is due to CO.

As noted, the LC

5Q

and the toxicological syndromes are different in the

2 experimental set-ups. A factor of 2 difference in the LCr

Q

values is

not too significant. However, the difference in toxicological syndrome

suggests that the mode of combustion is not entirely the same even though the chemical analysis shows very little difference.

4.0 Cotton Results

4.1 Analytical

A summary of the analytical results on cotton is shown in Table II.

This work is still in progress.

89
Carbon monoxide and carbon dioxide are somewhat higher in the protocol

system. At 40 mg/1 the ratio of C0/C0« for protocol system is 0.17 and

for the large scale is 0.20. Total hyarocarbon concentrations in the

test system are approximately 2 times the concentrations produced in the

large scale self-smoldering case.

4.2 Toxicological Comparison

The LC 50 for the cotton materials as determined by the test method in

the non-flaming mode is about 54 mg/1. Death was attributed to carbon

monoxide. Similar data from the large scale, although incomplete, gave

an approximate LC,-q of 60 mg/1. Again the cause of death was attributed

to carbon monoxide.

From the analytical and toxicological data on cotton, the test protocol

approximates a large scale self-smoldering fire very well.

REFERENCES

[1] Potts, W. J. and Lederer, T. S., "A Method for Comparative Testing of

Smoke Toxicity," Journal of Combustion Toxicity, Vol. 4, pp. 114-162

(May 1977).

[2] Clarke, III, F. B. and Ottoson, J., Fire Death Scenario and Fire Safety

Planning, Fire Journal, Volume 70, No. 3 (May 1976).

90
91
92
I Table 1

Preliminary Results from the Large and Small Scalp Tpst.s

Polyurethane Foam GM-21 Non-Flaming Mode

Combustion

Products

Maximum Concentration, ppm

Estimated from several runs

Combustion Concentration Exoosure Box Large

Products mo/1 Potts Furnace Scale

Total 15.6 3650 2500

Hydrocarbon 20.0

23.4 5500 3400

30.0 5000

40.0 6400

Carbon 15.6 1400 1450

rionoxide 20.0

23.4 2100 2100

30.0 3000

40.0 4000

Carbon 15.6 2060 2150

Dioxide 20.0

23.4 2750 2900

30.0 4300

40.0 5900

Hydrogen 15.6 6 9

Cyanide 20.0 8 15

23.4 "11 19

30.0 10 30

40.0 50

93
Table II

Preliminary Results from the Large and Small Scale Tests Cotton

Non- Flaming Mode

Combustion

Products

Smoke

Concentration Maximum Concentration, ppm

Small Large

Scale Scale

Total 10 1100 600

Hydrocarbon 20 2100 1100

30 3100 1600

40 4100 2000

50 4600 2500

55 4800 2800

Carbon 10 — 1000

Monoxide 20 1800

30 — 2500

40 4000 3200

50 4900 3900

55 5400 4200

Carbon

Dioxide

10

20

30

40

50

55

23300

27600

29000

3600

7100

10300

13200

16100

17500

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Figure 27. Spray Distribution Tests Clothing Wardrobe

103
Study of Toxic Gas Generated During Combustion

-- In Case of Natural & Artificial Lawn —

by

Yoichi NISHIMARU & Yukio TSUDA

Department of Legal Medicine

Yokohama City University, School of Medicine

October 16, 1980

For presentation at 5th UJNR Conference on Fire Research

( Japan - United States Panel on Natural Resources )

104
1. Introduction

In present Japan, the great interest and fear of

people's are strong earthquake attack. We, Japanese

people dwelling in those overpopulated cities and living

considers that if we encounter a strong earthquake,

damages and casualities must be beyond our expectations.

In such case, sufferers are supposed to seek refuge

at the public extensive refuge designated by each local

self-governing body. However, as refuges which require

certain extent are exceedingly limited in big cities,

Golfcourses, Baseball game studiams and so on are

designated actually.

Though Yokohama City which is the second biggest

city in Japan in its population, has a small mumber of

extensive refuges in a center of the city. Its typical

refuges are natural lawny golf courses or artficial

lawny baseball game studiam.

In case of a fire spread to those places, assuming

what sort of damages and casualities are occured, we

burnt artificial lawn and natural lawn in the experimental facilities for combution based on the standard

of the Ministry of Construction and then test on living

animals in it for studing what type of toxic gases

generated during combustion and how to influent on them.

105
2. Experiment & Result2-1. Control Experiment-1

One experimental group is eight ddy-male mice

( over 4 weeks after being born and their weight are

25-30g. ) . These normal mice before the absorption of

gases that produced by combustion, are killed and there

are taken value of pH and the dencity of CO, in total

blood ( their arterial and venous blood )

All parenchyma organs in their thorax and abdomen

are homogenized, are taken the density of CN in blood

by Pyridin-Pyrazolon method.

The result are shown at Fig. 1.

2-2. Control Experiment-2

** Experimental Apparatus Shown at Fig. 10.

2-2-1. Experimental Method & Result

The mice are placed in test chamber, and it burn

without test materials in furnace. Observed the condition of mice and gases. The behavior of mice being in

the test chamber are recorded by the mice-monitor, and

the concentration of gases ( HCL, CO, C0

2 , 02

) produced

during burn, are recorded by each analitical apparatus.

And the concentration of HCL are mesured by HCL test tube,

after 6 minites beginning the combustion.

The result are shown at Fig. 2 and Fig. 3.

106
** Combustion Method : When the appratus is switched

on, air ( 3 X/min. ) and propane-gas ( 350 mjl/min. ) are

automatically taken into the furnace. After this, the propane-gas is burned. After 3 minutes, electric heater ( 1.5

kw ) is switched on and after 6 minutes, switched off, in

automatically. Burn by propane-gas is put out after 10

minutes

2-3. Experiment-3 . ( Material : Natural lawn ) 2-3-1. Experimental Method & Result.

The method and object are same the Control Experiment

-2. In this time, the test material in furnace is natural

dry lawn ( 9 0g. )

The result are shown at Fig. 4 and Fig. 5.

2-4. Experiment-4 . ( Material : Artificial lawn ) 2-4-1. Experimental Method & Result.

In this experiment, we use the artificial lawn as

test material in furnace. This material is_90g. _in ; weight,

20x20cm. in width at one time.

The result are shown at Fig. 6 and Fig. 7.

107
3 . Summary

If a strong earthquake attacks a great town and

a fire accident occures, the people in the town will take

refuge in the public extensive refuge laid natural lawn

or artificial lawn on the ground.

Therefore, in this experiment, we conducted the

combustion test on natural lawn and artificial lawn

brewed polypropylene. Fig. 8 and Fig. 9 show the results

of each experiments ( Fig. 2-7 ). ** In the case of natural lawn :

1 ) The concentration of CO in the chamber was 0.35%,

while that of C0

2

was 4.6% and that ofHCN was 8.2 ppm.

The lowering of the quantity of 0

2

was 14%. Production

of HC1 has not been noted by test-tubes.

2 ) The concentration of CO in the blood of mice was

39.09%.

3 ) Only four mice among forty mice were dead.

** In the case of artificial lawn :

1 ) The concentration of CO in the test chamber was 0.83%,

while that of C0

2

was over 5%, and that of HCN was

6.3 ppm.. The lowering of the quantity of 0

2

was 13.1%.

Production of HC1 has been noted about 4600 ppm. by testtubes .

108
2 ) The concentration of CO in the blood of the mice

was 39.54%.

3 ) The all mice were dead.

The results of this experiment have shown, that

a place laid artificial lawn on the ground was unfit

for a public extensive refuge.

109
H I Concentration of carbon monoxide and hydrocyanide in blood

PH

concentration group The 1st group The 2nd group The 3rd group The 4th group The 5th group

Average

7.025

7.178

7.114

7. 336"

7.589

7.248

CO( %)

3.60

3.27

1.94

0.99"

7.20

3.40

HCN^g ml

110
2 Combustion on no test material in the furnace (Concentration of gases Maximum

temperature

in the furnace

concentration of poisonous

gases in the test chamber

O2 minimum

concentration

in the test chamber

17.2%

Number of dead mice

0

CO CO 2

II CN HCL

500 t 150ppm 2.30 % Oppm Oppm

520 f

495 t

lOOppm 2.25 % Oppm Oppm 17.8% 0

150ppm 2.15% Oppm Oppm 17.8% 0

490 r ISOppm 18.0% Oppm Oppm 18.0% 0

580 °Q 150ppm 2.10% Oppm Oppm 17.4% 0

517 "C 140ppm 2.18% Oppm Oppm 17.6% 0

g 3 Combustion on no test material in the furnace (Concentration

of carbon monoxide and hydrocyanide in blood)

^^concentration

group"

PH com HCN(ijg/ml)

The 1st group 7.098 0.00 0 The 2nd group 7.277 7.78 0 The 3rd group 7.196 3.99 0 The 4th group 7.154 3.59 0 The 5th group 7.073 13.91 0 Average 7.160 5.85 0

111
4 Combustion on natural lawn (Concentration of gases)

\\

Maximum

temperature

in the furnace

Concentration of poisonous

gases in the test chamber

Oj minimum

concentration

in the test chamber

Numbers of dead mice and

weight loss group CO co2 HCN HCI of material The 1st group

625 °C 0.45°, 4.0 % 14ppm Oppm 14.4 °

0 4 (65g)

The 2nd group

695 r 0.33 % 4.65", 6ppm Oppm U.0% 0 (65g)

The 3rd group

695 r 0.30 % 4.4 % 6ppm Oppm 14.7?,

0 (65g)

The 4th group

660 °C 0.33 % 4.95 c0 8ppm Oppm 14.2 ?5 0 (65g)

The 5th group

655 °C 0.33 °o 5.0 \ 7ppm Oppm 14.4 %

0

(65g)

Average 663

0.35 °

0 4.6 °

c 8.2ppm Oppm 14.3 =c 0.8 (65g)

5 Combustion on natural lawn (Concentration of carbon monoxide and hydrocyanide in blood)

L^concentration

group~~~~-

P H CO(?*) HCN(pg/ml)

The 1st group 7.228 29.07 0 The 2nd group 7.106 39.33 0

i The 3rd group 7.296 46.85 0

The 4th group 7.332 39.02 0

The 5th group 7.401 41.19 0

Average 7.268 39.09 0

112
6 Combustion on artificial lawn (Concentration of gases)

\

group \^

Maximum

temperature

in the furnace

Concentration of poisonous

gases in the test chamber

(J> minimum

concentration

in the test chamber

Number of dead mice and

weight loss CO C02 HCN HCI of material The 1st group

580 mc 0.72 % 4.95% 3.5ppm 2375ppm 13.8% 8 (54g) The 2nd

group

660 "C 0.87% over 5% 5 4ppm 3000ppm 13.2% 8 (60g) The 3rd group

655 "C 0.90% over 5% 6.0ppm 6050ppm 13.8% 8 (75g)

The 4th group

590 TC 0.66% 3.8% 3.0ppm 2100ppm 14.4 „, 8

(50g)

The 5th group

630 -C 1.02% over 5% 4.6ppm 13200ppm 12- 5 % (65g)

The 6th group

675 'C 0.78% over 5% 10.5ppm 800ppm 12.2 „ 8 (59g)

The 7th group

670 "C 0.84 %

over

5 %

1 l.Oppm 4840ppm 11.8,, 8 (37g)

Average 637 r 0.83% over

5 %

6.3ppm 4623ppm 13.1 %

8

(56. 7g)

H 7 Combustion on artificial lawn (Concentration of carbon monoxide and hydrocyanide in blood)

^"\^concentration

group P H CO m HCN (ug/ml)

The 1st group 6.470 34 67 0 The 2nd group 6.506 49 90 0 The 3rd group 6.579 43 58 0 The 4th group 6.361 37 92 0 The 5th group 6.443 24 57 0 The 6th group 6.757 37 60 0 The 7th group 6.863 48 53 0 Average 6.568 39 54 0

113
m. 8

Combustion

on no test material Combustion

on natural lawn Pn\_ U m1 1 1 hnct U Ll 0 1 1

1 fiu n1

1

on artificial lawn

CO 140 ppm. 0.35 % 0.83 %

02 17.6 % 14.3 % 13.1 %

CO 2 2.18 % 4.60 % over 5.0 %

HCN 0 ppm. 8.2 ppm. 6.3 ppm. HCI 0 ppm. 0 ppm. 4.623 ppm. N umber

of dead mice

0/40 4/40 56/56

Temperature

in the furnace

517 *C 663 r 637 r

8 9

Control Combustion

on no test material Combustion

on natural lawn

Combustion

on artificial lawn

PH 7.248 7.160 7.268 6.568 CO(%) 3.40 5.85 39.09 39.54 CN (yg/ml) 0 0 0 0

114
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115
Discussion of Presentations on Toxicology

Saito Presentation

Benjamin: I have a question regarding Figure 2. We reported to the

Panel a couple of years ago on the work done by Johns Hopkins University

on a similar study of autoposies. The findings at that time indicated

that over 80% of the deaths could be attributed to carboxyhemoglobin.

Figure 2 would indicate that the conclusions that we had drawn—that

carbon monoxide was the prime factor in deaths—may not be a correct

conclusion. I would like to ask Dr. Saito if he has any ideas as

to why we seem to be different.

Saito: In my opinion there is a difference in the availability of

autoposies for fire death between our two countries. In Japan, an autoposy only was done for the case if it was connected to a crime.

However, in United States autoposies are done relatively easy. I would like to confirm this with Prof. Nishimaru.

Nishimaru: In Figure 2, we believe that at least 50% of deaths were

caused by CO. I notice that recent Johns Hopkins data indicate that

this rate changed from 80% to 60%. In my opinion, it is not clear

whether the availability of autopsy in Japan, as mentioned by Dr. Saito,

or different materials used in Japan are the cause of different types

of toxicants.

Myers: Again in reference to Figure 2, we are looking at a small

number. I don't think there is that much variance from our own clinical experiments. In our clinical experiments involving some work on a current report, we have been taking blood samples from

people involved with fires—survivors in the field—and we have found

that the blood caroxyhemoglobin HBCO level at the field is dramatically

higher than the indications in the hospital twenty minutes later;

field level is 60 and hospital level is 40. In looking at your figure,

it would appear that your people were dying with higher levels of

carbon monoxide. There are a great number above 50%, but Halpin and

Fisher's data are lower than that. It may be the materials of the

fire in the building that makes the difference, if there is a difference.

Nishimaru: Your report on the different discrepancies between figures

of blood samples in the field and in the hospitals has been very

informative. The Dr. Halpin that you mention, is he the Medical

Examiner in New York? We noticed some difference in data between

Halpin 's and ours. It might be due to the difference in materials.

Myers: Dr. Halpin was one of the people on the Hopkins grant. Dr.

Fisher is the Medical Examiner in Baltimore, Md.

116
Birky Presentation

Saito: I would like to ask two questions. Is there a significant

difference in gas concentration (mg/1) between the large scale

experiment and the small scale one. I think there may be a significant

loss of combustion products through the sampling line between the

chamber to the detector instrument.

Birky: Yes, that is correct and may be part of the problem. The

other part of the problem is that in the large scale experiment, we

take about an hour and a half to generate the concentration required

to expose the animals. So we have time for loss of reactive components.

Saito: The table showed mg/1 as units. Is a time factor included

in this figure.

Birky: The exposure of the animals takes place over thirty minutes

in both cases. However, to generate the products takes longer in the

large scale.

Saito: You described that the smoldering mode was used for the large

scale experiment and the small scale one. Could we assume that the

smoldering condition is identical for both the scales?

Birky: No, in the small scale we have the sample decomposed in a furnace that is preset at some temperature.

117
Nishimaru Presentation

Birky: Was exposure time three minutes?

Nishimaru: With which samples?

Birky: Didn't you test all the materials the same way?

Nishimaru: I will try to explain the burning condition used in this

study. 3 1/min of air and 350 ml/min propane, 1.5kw electric heater

were turned on. Six minutes later, the electric heater was automatically turned off and the propane gas was turned off ten minutes later.

Therefore, animals in the chamber were exposed to products for fifteen

minutes

.

Birky: Does the concentration of the gases in the table represent

the average over that 15 minute period?

Nishimaru: Yes.

Birky: In Table 1 does it concern you that the variation is fairly

large from a biological point of view?

Nishimaru: Do you mean from 7.25 to 7.58?

Birky: Yes, are those control values?

Nishimaru: Yes, principally it is. The pH value shown in Figures 1

and 3, should be about the same because there are no effects of products.

However, there are some scatter and we interpret this as a biological

difference among individual animals.

Birky: In terms of interpretation of Tables 6 and 7, how do you

establish a correlation between any of the factors in those two tables?

For example, what is the cause of death and correlation to reduce pH

to the highest P level?

Nishimaru: Since the amount of each toxicant is way beyond the

critical amount for the correlation, it is rather difficult to evaluate.

I misunderstood the previous question. O2 and COo concentrations are automatically recorded. Values shown in figures are maximum CO2 and

minimum O2.

Huggett: We find that the toxic dangers being associated with

materials depend on the toxicity as measured in laboratory tests, but

also on the quantity of material and the probability that it is likely

to be involved in a fire. We find that carpets, floor coverings,

118
ground covers are difficult to involve in a fire. They usually will

burn only if they are preheated by radiation from a ceiling, from a hot

gas in a large fire. I find it difficult that you could get a substantial fire on a carpet (ground cover) in the open, such as a golf course. I wonder if any tests have been run in determining the likelihood of a fire developing under the conditions that this material is

being used?

Nishimaru: I do not have any experience with that. I agree that

we do not worry about fire hazards for golf courses. It might be an extreme case, but I keep remembering what happened fifty years ago.

Japan had a very serious earthquake which caused extremely large fires

and many deaths and included large buildings. We do not know what

caused the deaths of the people in this extreme case. The Japanese

government suggests that we don't use any kind of potentially toxic

materials. We should use safe materials. With this in mind, we tested

these materials. In crowded places such as a baseball stadium, it might

happen as an extreme case. So, our point of view is just in case.

Saito: In Japanese building code, the floor materials are considered

to be less fire hazardous at early stage of fire and were not included

in the fire code. Prof. Nishimaru considered these materials as a chemical compound instead of floor covering for artificial turf. The

floor covering might get involved after flashover. Then, this study

might be useful.

Clarke: The issue raised here, expressing the evolution of hydrogen

chloride, prompts me to ask a related question of a somewhat different

subject of this paper. In the United States we have very little work

going on in the treatment of fire victims who have inhaled hydrogen

chloride and yet this is going to be a problem because of the increasing

prevalence of chloride-containing polymers in the environment. Has

there been any research in Japan that Prof. Nishimaru and colleagues

know of on the treatment of HCl (hydrogen chloride) inhalation?

Nishimaru: My personal opinion is that there is not much affect

of these gases on plants, animals or humans. However, it is almost

impossible to remove all these gases or all materials which produce

these gases from our present society. After this meeting, I will

discuss with Dr. Saito how we will explore a new type of study to

determine if animals will survive without permanent damages after we

stop the test in the middle of experiment; rather than the present type

test in which we continue the test until the death of the animals.

119
Clarke: We have a few cases in the U.S. of people being injured where

the symptons look very much like hydrogen chloride inhalation, although

I know of no cases where it was definitely established that that was the cause of the problem. But I share the view that chloride containing

materials are increasingly finding their way into the environment and we may find this to be more of a problem in the future. The most likely

victims of exposure to this kind of situation would probably be the

firefighters. How common is the use of breathing apparatus—independent

air tank—by Japanese firefighters?

Jin: When firefighters go into a smoke filled area, they usually

breathe from air tanks.

Benjamin: Dr. Jin mentioned that the firemen will wear their mask

when there is visible smoke. Our experience has been, particularly

with PVC type fires, that the smoke was not visible and many of the

injuries have been the result of firemen who went into an atmosphere

where there was no visible smoke and they did not put their masks on.

Jin: When the smoke is visible, obviously, then it is mandatory

that they wear gas mask. Where you don't see any smoke, they have

to decide whether or not to wear the mask. If toxicants are expected,

then they wear the mask; otherwise they just go in without masks.

I personally do not know any casualties caused by invisible toxic

atmosphere. Medical doctors of the laboratory of Tokyo Fire Defense

Agency are studying the toxic hazards of combustion products and they

recommend more awareness of the danger of these gases for firefighters

than used to be.

120
4. ADVANCES IN SPRINKLER TECHNOLOGY

121
LIFE SAFETY FACTORS INVOLVED IN THE

USE OF SPRINKLERS

John G. O'Neill

Center for Fire Research

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

122
LIFE SAFETY FACTORS INVOLVED IN

THE USE OF SPRINKLERS

John G. O'Neill

1 . INTRODUCTION

The Center for Fire Research (CFR) at the National Bureau of Standards

(NBS) has conducted an extensive research program into the use of automatic

sprinklers in health care facilities. The purpose of this paper is to present

some of the results of this project which may impact future installation criteria

and product design criteria for automatic sprinklers in health care facilities.

These results may also apply to other occupancies where life safety is also the

primary purpose for installing automatic sprinklers.

The CFR project, which was originated in 1977 and then resumed in 1979,

consisted of a series of full-scale tests to develop engineering design information concerning the use of automatic sprinklers to minimize life loss and

injury in the event of fire in health care facilities.

An interim report by O'Neill and Hay^s has been published and it covers

the first eight tests in this project [1] . A final report on phase II of the

project was published in July, 1980 [2].

2. OVERALL PROJECT OBJECTIVE

The overall project objective was to measure the performance of the sprinkle

in terms of:

a. Overall fire control.

b. Time available for evacuation of patients in the fire area.

c. Maintaining tolerable environmental conditions for patients who

cannot be evacuated.

3. EXPERIMENTAL FACILITIES

3.1 Test Area and Instrumentation

The experimental approach used in this project was to conduct full-scale

fire tests in a two patient sized room with an adjoining corridor and a remote

room located at one end of the corridor, as shown in figure 1. The performance

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

this paper.

123
of the sprinklers in these tests was determined through the analysis of data

recorded with instrumentation installed in key locations throughout the test

area. The instruments measured temperatures, total heat flux, weight loss of

burning items, gas velocities, carbon monoxide (CO), oxygen and smoke obscuration. Measurements of gas temperature and velocities, CO and smoke obscuration

were made at different elevations in the doorway to the patient room and in the

corridor in order to obtain a profile of smoke movement and CO concentrations

during the tests.

3.2 Automatic Sprinkler System

The automatic sprinkler system for this project provided use of either a center ceiling pendant sprinkler in the patient room or a horizontal sidewall

sprinkler located over the door opening in the patient room. Flow rates to the

sprinklers were established prior to and maintained throughout each test by

means of a control valve and flow meter located outside the test area. Generally,

the water flow for the sprinkler in the patient room was set at 102 £/min (27

g/min) to provide the equivalent specified minimum flow resulting from one sprinkler head operating if the system was hydraulically designed in accordance

with the National Fire Protection Association (NFPA) Standard No. 13 [3]. The

standard requires a minimum average density of 4.1 mm/min (0.10 g/min/ft2

) for

this type of occupancy. The standard, however, states that for this type of

installation sprinklers outside the room must be considered in the calculation.

This requirement resulted in an actual 6.9 mm/min (0.17 g/min/ft 2

) density with

one sprinkler operating in the room.

Sprinklers "sed in the project included 13 mm (1/2 in) and 10 mm (3/8 in)

pendant sprinklers and 13 mm (1/2 in) horizontal sidewall sprinklers which meet

the requirements of UL 199 [4].

In addition to the "wet" sprinkler head, three dry sprinkler heads were placed at the center of the burn room ceiling. The purpose was to obtain data

on response times of other types of sprinkler heads in the full-scale fire

tests. The dry sprinkler heads were pressurized by nitrogen which was pumped

through copper tubing placed above the fire resistive ceiling. A pressure

switch was connected into the tubing which led to each sprinkler head and, when

the sprinkler operated, the pressure switch activated a relay which stopped a clock. Thus, response times relative to time of ignition were automatically

recorded. Dry sprinkler heads included the following fusible elements:

Rapid-response 57°C (135°F) (commercially available)

Fusible pellet 74°C (165°F)

Link-lever 75°C (165°F) duplicate of wet sprinkler head

3.3 Ventilation of Test Area

A simulated heating, venting and air conditioning (HVAC) system was installed

in the burn room for the tests reported in this paper. The HVAC system consisted

of a supply duct mounted high in the wall, and an exhaust duct in the lower

124
opposite wall as shown in figure 2. The air flow rate for the burn room was

based on criteria contained in the Minimum Requirements of Construction and

Equipment for Hospitals and Medical Facilit ies [5]. This standard requires a minimum ventilation rate of 2 air changes per hour for patient rooms with zero pressure difference between the patient room and corridor. For this sized room

the flow rates for both supply and exhaust were established at 1.2 m

3 /rain (42

ft 3 /min) to give the minimum air change rate without creating an air flow

between the patient room and corridor. A fan coil unit was installed to provide

recirculated air in the room. A separate system provided conditioning for the

burn room to maintain a limited range of temperature and relative humidity

conditions in the burn room throughout the series of tests. The fan coil unit

was set at a low speed which recirculated air in the burn room at an approximate

rate of 3.4 m

3 /min (120 f3 /min)

4. ELEMENTS OF HAZARD ANALYSIS

Consistent with the overall project objectives the results of the fire

tests were measured in terms of the following:

Fire Spread

Heat Flux

Toxic Gases

Smoke Obscuration

Specific quantitative values for fire spread were not developed to measure

the performance of sprinklers. However, weight loss data as well as the record

of visual observations were analyzed to determine the relative performance of

sprinklers in limiting fire growth.

Quantitative values were selected as estimated limiting conditions for the

other elements. These values based on previous studies, were as follows:

a. For the heat flux measured at the adjacent patient level a threshold

for burn injury of 2.5 KW/m2 was selected as an upper limit prior to one feeling pain [6].

b. A threshold of 25% carboxyhemoglobin was established as a limiting

condition for continuous exposure to CO [7]. A concentration of 1%

(10,000 ppm) CO was selected as a hazardous threshold for instantaneous exposure to CO [8].

c. A minimum of oxygen concentration of 14% was selected as a lower

limit for determining the impact of O2 depletion on occupants [9].

125
d. For smoke obscuration two limiting conditions were selected. The first

concerned the rescue of a patient inside the room of fire origin. A smoke

obscuration threshold of 0.5 OD/m was estimated as the level where rescue

of a patient would be impaired. The second concerned egress in the

adjoining corridor. A threshold of 0.25 OD/m was estimated as the level

where movement in the corridor would be impaired [10, 11]

5. TEST PROCEDURES

The series of full-scale fire tests and sprinkler spray distribution tests was based on fire scenarios involving either bedding and mattresses or clothing

wardrobes in a two patient room environment. These furnishings represented

typical contents in patient rooms of health care facilities and in the test

procedures they served as the principal burning items. The experimental procedure for the sprinkler evaluation was limited to the flaming ignitions of

these items.

5.1 Mattress and Bedding Fires

In all fire tests where a mattress and bedding served as the burning

items, a hospital specified polyurethane innerspring mattress was used. The

bedding which consisted of various cotton and cotton polyester materials, was

also specified for hospital use. In several tests a privacy curtain was installed

around the bed and located between the bed and the pendant ceiling sprinkler to

determine the effect on sprinkler performance.

The test was initiated when the contents of a small waste container next

to the bed were ignited with a match and the fire then spread to the bedding

and then to the mattress. As discussed in the interim technical report, this

procedure was very repeatable [1].

5.2 Clothing Wardrobe Fires

The clothing wardrobe fire scenario was also included in the project in

order to assess the impact of sprinklers on what was estimated to be a very

severe (but also realistic) fire in a patient room.

In an effort to develop a reproducible test fire, the same loading was

initially used in each test. The loading consisted of various fabrics which

represent materials found in present day clothing. The materials were placed

on wire coat hangers and arranged loosely in the wardrobe to provide a clear

space between each hung fabric. This arrangement was chosen since it was desirable to have a fire which would develop rapidly inside the wardrobe. A

cardboard box containing crumpled newspaper was placed on the floor of the

wardrobe and the newspaper served as the pilot flame inside the wardrobe. Each

126
wardrobe test started when the crumpled newspaper was ignited with a match.

Following ignition the left hand door was closed tightly while the right hand

door was left partially opened resulting in a 7.6 cm (3 in) opening along the

vertical edge of the door. The position of the wardrobe in the patient room is

shown in figure 3.

6 . RESULTS

6.1 Mattress and Bedding Test Results

In tests where the mattress and bedding served as the burning items, the

estimated limiting condition for smoke obscuration was exceeded with both the

standard pendant and horizontal sidewall sprinklers. The range of response

times for the 165°F (74°C) pendant sprinkler was from 330 to 388 sec. In one

test in which a standard 160°F (71°C) horizontal sidewall sprinkler was installed,

the response time was 388 sec.

The estimated limiting conditions for smoke obscuration as measured at the

patient room doorway and in the corridor were exceeded before the sprinklers

operated. The smoke layer lowered to within .9 to 1.2 m (3 to 4 ft) from the

floor before sprinkler operation. Following sprinkler operation, there was essentially total obscuration from floor to ceiling throughout the test area. It

should be noted that in previous tests involving the same type of mattress and in

which sprinklers were not installed, the smoke filled the corridor and also created

essentially total obscuration from floor to ceiling.

None of the other estimated limiting conditions outlined in paragraph 4 were

exceeded except for carboxyhemoglobin levels in the fires where the privacy curtain

was installed. These results are discussed in 6.2.1.

6.1.1 Movement of Smoke and CO - Analysis of Data

The impact on smoke movement by the sprinklers was significant, especially

in the doorway where velocity measurements, smoke meters, and gas measurements

indicated a reversal of flow of smoke through the doorway and the shifting of

peak CO concentrations from ceiling to floor level. Figure 4 provides the

record of CO measurements in the burn room and doorway for Test N-37. Concentrations of CO shifted after sprinkler actuation at 330 sec. The CO data from

the corridor instrumentation tree indicated that the sprinkler acted to redistribute the smoke layer (represented by the CO measurements) away from the

immediate area of sprinkler actuation. Figure 5 gives the CO measurements at

the corridor tree. Following the initial sprinkler flow, higher concentrations

were recorded at 0.9 m (3 ft) and 1.5 m (5 ft) from the floor. The concentrations

measured near the ceiling were lower than those measured at the other elevations

following sprinkler actuation.

The concentrations of CO measured at all locations were low and estimated

COHb levels did not exceed a limiting condition of 25% in tests where the

privacy curtain was not installed. The increase in CO in the corridor and the

redistribution of the CO throughout the test area, however, verified that, in

these types of fires, the sprinkler acted to lower the smoke layer throughout

127
the test area and to project the combustion products from the patient room into

the adjoining corridor at a more rapid rate than before the sprinkler operated.

This resulted in the severe smoke obscuration recorded throughout the test area which in an actual health care facility could seriously hamper the movement of

staff and patients in the adjoining corridor.

An analysis of the data revealed that the smoke filling rate in the test area was roughly proportional to the fire growth rate as reflected in the

record of gas temperatures measured at the ceiling in the center of the burn

room. Figures 6 and 7 demonstrate this correlation where the depth of the smoke

layer is defined as the time a smoke meter located in the doorway or in the

corridor measured an obscuration of 0.25 OD/m. This boundary value for the

smoke layer was arbitrarily established in this analysis in order to assess the

impact of sprinkler response time as a function of the estimated depth of the

smoke layer in the test area. (As mentioned in section 4, 0.25 OD/m was selected

as a hazardous threshold for visibility and personnel movement in the corridor.)

Figure 6 provides the results of Test N-37 in which a pendant automatic

sprinkler was installed in the center of the room. Although the sprinkler had

a temperature rating of 165°F (74°C), the thermal lag of the fusible element was

such that the sprinkler finally operated at 330 sec. At this point the ceiling

gas temperature had reached 200°C near the sprinkler and the smoke layer had

lowered to approximately 0.9 m (3 ft) from the floor.

This lag was even more significant in a test in which a horizontal sidewall

automatic sprinkler was located over the door. The sprinkler had a temperature

rating of 160°F (71°C) and at time of actuation. 388 sec, the smoke layer was

less than .9 m (3 ft) from the floor. See figure 7.

By plotting the smoke filling rate on the same time axis as the ceiling gas

temperatures, one can see that a fusible element operating at approximately

135°F (57°C) would actuate the sprinkler when the volume of smoke in the patient room and corridor was significantly less than when the standard 74°C sprinkler

actually operated. Since the instrumentation as well as visual observation

revealed that the flowing sprinkler lowered and redistributed the smoke layer,

it follows that if a sprinkler operated sufficiently early enough in the fire,

there would be significantly less smoke and toxic gases such as CO present to be

redistributed by the sprinkler. Based on this, the project focused on the

investigation of sprinklers operating at an earlier stage of the fire development and their impact on smoke movement.

6.1.2 Simulated Rapid Response Sprinkler Tests

6.1.2.1 Preliminary Test

In Test N-37, a commercially available dry sprinkler which was rated for

135 F (57 °C) operating temperature and designed for rapid response, responded at

285 sec. At this time, as shown in figure 6, the center ceiling gas temperature was approximately 120°C and the smoke layer in the corridor had lowered to

within 4 ft from the floor.

128
This suggested that a fusible element with a thermal inertia lower than

that which exists for current technology sprinklers was necessary if the sprinkler

was expected to operate shortly after the gas temperature near the sprinkler

reached its nominal temperature rating.

Initially, a test (No. N-38) was conducted to determine the feasibility of

preventing the smoke obscuration from reaching hazardous thresholds by actuating

the sprinkler sufficiently early in the fire. This test included the same mattress, bedding, and waste container ignition sequence described earlier.

The sprinkler system consisted of an open 10 mm (3/8 in) pendant sprinkler

arranged to flow 64.3 £/min (17 g/min) which provided an average density of 4.1

mm/min (.10 g/min/ft2

) in the burn room. The open sprinkler was fitted with a resilient plug, and the system piping was primed with water downstream of a closed control valve.

During the fire test the gas temperature measured near the sprinkler was continuously monitored. To simulate the rapid response, the sprinkler valve

was opened at 10 seconds after the time the center ceiling gas temperature at

the sprinkler reached 135°F (57°C). The sprinkler was opened at 105 seconds

into the test and the subsequent smoke obscuration was very low throughout the

test area. The maximum obscuration measured at 1.7 m (5 ft 8 in) in the burn

room doorway and at 1.5 m (5 ft) in the corridor were 0.10 and 0.086 OD/m

respectively. These levels were considerably below the estimated limiting

conditions

The results of this test indicated that for this type of fire, the smoke

obscuration problem both before and after sprinkler operation could be greatly

reduced by means of a sprinkler with a low thermal inertia fusible link which

would operate soon after the ceiling gas temperature reached 57 °C.

6.1.3 Verification Tests

Following this preliminary test the investigation sought to quantify the

dynamic heating measurement of a successful fast response sprinkler in terms of

a dynamic heating test which was proposed by Factory Mutual Research (FM) and

is discussed in the appendix [12] . The dynamic heating measurement of the

fusible element is expressed as a time constant "t". In order to model sprinklers

with a t less than standard sprinklers (i.e. fusible elements with a thermal

inertia lower than standard sprinklers) , FM manufactured and furnished brass

discs designed and verified for t factors of 9.0, 14.4 and 21.5 sec. The

temperatures of these discs were measured and the data were used during the

tests to activate simulated fast response sprinklers.

The results of these tests verified that smoke obscuration was significantly

decreased with the use of fast response sprinklers with a time constant of

approximately 21.5 sec. Figures 8 thru 10 demonstrate that the use of a fast

129
response pendant or horizontal sidewall sprinklers (Tests N-40 and N-45) resulted

in significantly lower smoke obscuration than in the tests with standard pendant

and horizontal sidewall sprinklers (Tests N-37 and N-39)

6.1.4 Discussion

The tests discussed in this section were conducted in a limited volume test area which represented a typical patient room and corridor arrangement but it

did not represent as great a volume as would likely be in a smoke zone in a health care facility. Thus, limited extrapolation could be made for other

geometries and larger volumes. Despite the limitations which prevent extensive

extrapolation to other building sizes, the experimental work reported here

clearly demonstrates that a lower thermal inertia or fast response sprinkler can reduce significantly the impact of smoke obscuration for a patient room mattress

and bedding fire. Since the lowering of the heated gas layer and severe obscuration

was immediate in and near the patient room, where the conventional sprinkler

operated, this phenomenon suggests that the obscuration problem is severe near

the room of fire origin regardless of the volume of the building or smoke zone. The impact of the fast response sprinkler, in reducing the smoke obscuration

problem in and near the room of fire origin, could increase the time available

to rescue the patients closest to the fire.

6.1.5 Impact on Sprinkler System and Hardware Design

In addition to these findings, the results of an ongoing residential

sprinkler test program have indicated that the dynamic heating characteristic of

a sprinkler is an important variable in the performance of a residential sprinkler

system. (This test program is being conducted by NFPA, Factory Mutual Research

and the Los Angeles City Fire Department and sponsored prinicpally by the U.S.

Fire Administration.) In earlier tests FM determined that a sprinkler fusible

element of a t = 21 sec was needed to insure that the sprinkler would operate

early enough in the fire to prevent flashover in a ventilated living room test

fire [13].

The results of both of these programs, the residential sprinkler program

and the CFR patient room sprinkler program strongly suggest that product testing

criteria should include a dynamic heating measurement. For life safety, the

results also suggest the need for a more rapidly responding sprinkler than

conventional sprinklers. It should, however, not be inferred that sprinklers,

in general, should respond faster than a standard conventional sprinkler. In

industrial and storage occupancies where it is desirable to limit the number of

operating sprinklers to prevent the overtaxing of the water supply, a high t factor, (i.e. slow response) sprinkler may be more effective. In any case it

appears that a dynamic heating measurement of the sprinkler, in addition to the

temperature rating of the sprinkler, should be a primary design variable in future

sprinkler criteria.

130
6.2 Privacy Curtain Tests

6.2.1 Fire Tests

In several mattress and bedding tests a privacy curtain was placed around

the bed as shown in figure 2. The purpose of these tests was to determine the

effect of the privacy curtain on the sprinkler spray distribution and subsequent

fire control by the sprinkler. The results of the tests indicated that the

sprinkler cooled and controlled ceiling temperatures in the burn room. The

results, however, also indicated that CO concentrations were higher throughout

the test area when the privacy curtain was present. The differences in CO

concentrations are shown in figures 11 and 12 for Test N-25, without the privacy

curtain and Test N-33 with the privacy curtain. In Test N-33, calculated

carboxyhemoglobin levels at the adjacent patient level exceeded the estimated

limiting condition of 25% approximately 20 minutes after ignition. After Test

N-33 was completed, it was noted that the mattress and bedding were totally

consumed. (In tests without the privacy curtain, approximately 20% of the

bedding and mattress was consumed prior to final extinguishment by the sprinkler.)

It was clear that the position of the privacy curtain with respect to the

sprinkler as shown in figure 13 presented a serious obstacle to the sprinkler

spray distribution. The higher concentrations of CO were apparently due to the

position of the privacy curtain which shielded the burning bed from the water

spray and adversely affected the extinguishing performance of the sprinkler.

6.2.2 Spray Distribution Tests

6.2.2.1 Test Plan and Procedure

Based on these findings an investigation was conducted to quantify the

interference of the privacy curtain in terms of spray distribution; and to

develop recommendations concerning the location and arrangement of the privacy

curtain with respect to the sprinkler. A simple collection container array was

installed in the burn room at the location of the bed to obtain spray density

measurements over the horizontal plane of the bed, as shown in figure 14.

The results of these non-fire tests clearly indicated that the privacy

curtain as installed in the previous fire tests severely blocked the water

spray from the sprinkler. Figures 15 and 16 provide a comparison of results of one of the pendant sprinkler tests with and without the privacy curtain.

Repeated tests with other models of pendant sprinklers and a horizontal sidewall sprinkler provided similar results.

The investigation then proceeded to determine design information on the

placement of the privacy curtains with respect to the sprinkler to minimize the

impact of the curtain on the spray distribution of the sprinkler.

131
Initially criteria were established for the minimum spray density which was necessary to extinguish a fire involving a mattress and bedding. Kung et al.

suggested a critical application density of 1.4 mm/min (0.033 g/min/ft 2

) for halting

fire spread underneath a urethane foam mattress [14].

To facilitate the experimental work, a plywood screen was fabricated and it

served in the place of the privacy curtain. As various tests were conducted

with sprinklers flowing at 102 £/min (27 g/min) the screen was raised and

lowered and moved to various positions horizontally in an effort to determine

the position boundaries for the cases where the critical density could not be

obtained. During the experimental work it was noted that variations existed

among standard pendant sprinklers of different manufacturers, such that, the

spray from one tended to project more water directly parallel to the plane of

the deflector than others. Therefore, measurements were made for these different sprinklers in order to insure that recommendations developed from the

experimental work were not biased toward the most favorable spray pattern.

Spray distribution measurements were also conducted with the horizontal

sidewall sprinkler to determine the impact on the sprinkler spray pattern. The

simulated curtain was placed 40.6 cm (16 in) from the foot of the bed and 68.6

cm (27 in) from the corridor wall, with the height of the curtain being varied

for each measurement. The flow from the sprinkler was also set for 102 Jl/min

(27 g/min) to provide an average density of 6.9 mm/min (.17 g/min/ft 2 ).

6.2.2.2 Results

In all of the spray distribution tests it was observed that the collectors

which were placed along the wall collected most of the water which hit the wall.

While the wetting of the wall may be an important benefit, the quantities of

water collected in these containers do not reflect the actual density for that

"slice" of the horizontal plane of the protected surface. Therefore, data

obtained from these containers were not included in the calculation of the

average density over the plane of the bed.

The results of the tests with pendant sprinklers verified that the effective

spray density reaching the bed was dependent on both the vertical distance of

the top of the privacy curtain from sprinkler deflector and, the horizontal

distance of the curtain from the sprinkler. With the screen placed directly

beneath the deflector of the sprinkler, there was no adverse effect on the

effective density reaching the bed. As it was moved from the sprinkler toward

the bed the screen was progressively lowered to achieve the minimum density

criterion of .033 g/min/ft2

. Data shown in figures 17 and 18 indicate some of

the results which served as the basis for the recommended installation criteria

shown in figure 19. These criteria include a vertical distance from the sprinkler

deflector to the top of the curtain as a function of the distance of the curtain

up to 15 inches away from the sprinkler. k linear approximation has been

developed as a guideline for the installation of privacy curtains installed

further than 15 inches from the sprinkler. The formula is as follows:

132
Y = 0.5x + 0.5

where x = horizontal distance of curtain from sprinkler

Y = vertical distance from top of curtain to sprinkler deflector

The horizontal sidewall sprinkler was found to project a high percentage

of the discharged water toward the ceiling and in a radial direction horizontal

to the center line of the orifice. This spray pattern reduced the effect of

the privacy curtain on the horizontal sidewall sprinkler as compared to the * pendant sprinkler. The results as shown in figures 20 and 21 indicated that a minimum average effective density could be achieved over the plane of the bed

if the height of the privacy curtain was equal to or lower than the height of

the horizontal sidewall sprinkler.

6.3.1 Nonsprinklered Wardrobe Fire

In order to obtain a baseline for evaluating the performance of sprinklers

when exposed to combustible wardrobe fires, a fire test (No. N-54) without

sprinklers was conducted.

The initial rate of fire growth was essentially the same as in the tests

with sprinklers. With no other furnishings in the room, flashover occurred at

approximately 120 sec. into the test (see figure 22). At this time all limiting

conditions were exceeded throughout the test area. Several smoke meters in the

corridor and in the doorway were damaged by heat and much of that data was

lost. Measurements made at the key elevations in the doorway and in the corridor,

however, indicated that limiting conditions had already been exceeded prior to

the instrument failures. The test was terminated at 480 sec. when an open

sprinkler was activated.

6.3.2 Pendant Sprinkler Test

In the initial wardrobe test, No. N-48, a standard 160°F (71°C) pendant

sprinkler was installed and arranged to provide the 6.9 mm/min (.17 g/min/ft2

) density. As expected the fire quickly enveloped the interior of the wardrobe

and gas temperatures in the burn room rose rapidly. Following actuation of the

sprinkler, the ceiling gas temperatures were lowered as shown in figure 22;

however, the fire could still be seen burning inside the wardrobe for approximately 60 sec. following the initial flow of the sprinkler. Eventually, the

smoke obscuration prevented any observations of the burn room from a window in

the corridor across from the burn room doorway.

Analysis of the data from this test indicated that concentrations of CO were very high throughout the test area. The instantaneous limiting condition

of 1% was exceeded not only in the patient room but also in the remote lobby

area (figures 23 and 24) - Estimated COHb percentages also well exceeded the

limiting condition of 25%.

133
This test was repeated and the overall results were comparable. The fire

developed rapidly inside the wardrobe and, although CO concentrations were

slightly less than in No. N-48 , limiting conditions were exceeded or approached

in the burn room at the adjacent patient level, at the 1.5 m (5 ft) elevation

in the corridor as well as in the remote lobby area.

6.3.3 Horizontal Sidewall Sprinkler Tests

Using the same wardrobe fire scenario, a test was conducted using a standard

160°F (71°C) horizontal sidewall sprinkler set to provide a 6.9 mm/min (.17

g/min/ft 2

) density. The sprinkler was installed over the door as in the previous

mattress test (N-39)

.

The initial fire development was as rapid as in the previous tests and

following sprinkler actuation, the fire was visible for a brief time inside the

wardrobe. As in the previous tests tbe visibility was limited soon after

sprinkler operation. A major difference, however, was noted in the CO con- centrations, compared to the previous tests with the pendant sprinkler. CO

concentrations were significantly lower; the instantaneous threshold level of

1% was not reached, and the 25% COHb was exceeded only in the burn room at the

adjacent patient level at approximately 17 minutes after ignition. The test was repeated, (No. N-51) and approximately the same results were obtained.

Figures 25 and 26 provide the record of CO.

The record of total weight losses of the combustible wardrobes for the four

tests tracked closely with CO data. In the pendant sprinkler tests the weight

losses and CO concentrations throughout the test area were much higher than in

the tests with the horizontal sidewall sprinklers. See table 1 and figures 23

thru 26. These measurements indicated that the horizontal sidewall sprinkler

achieved better fire control than the pendant sprinkler.

In the initial analysis of the results, it was believed that the orientation

of the partially open wardrobe door with respect to the direction of the spray

from the horizontal sidewall sprinkler allowed more water to penetrate the

interior of the wardrobe. Spray distribution measurements were made in nonfire

tests for both the pendant and horizontal sidewall sprinklers operating at the same flow rates as in the actual fire tests. The results of the tests are shown in figure 27. Tbe spray measurement tests indicated that no more water

penetrated the wardrobe with the horizontal sidewall sprinkler than with the

pendant sprinkler.

6.3.4 Simulated Rapid Response

Analysis of the disc temperature data from the sprinklered wardrobe tests

indicated that fast response sprinklers would have operated only 10 to 15 sec. prior to the actual standard sprinklers. A review of the photographic record

of the test showed that at the time the discs reached 57°C the fire was just

beginning to issue from the wardrobe. Two tests were conducted each simulating

a fast response, x = 21 sec, 57°C fusible element; one test (N-53) with the

134
pendant sprinkler and the other (N-52) with a horizontal sidewall sprinkler.

The purpose of the tests was to determine if the extinguishing performance of

the sprinklers could be improved through the use of fast response sprinkler.

As shown in figures 23 thru 26, and in table 1, no significant improvements

were noted for either sprinkler over the standard fusible element sprinklers.

It appeared as though the fire growth rate inside the wardrobe had reached the

point where the spray from the fast response pendant sprinkler could not extinguish the fire any better than the standard fusible element sprinkler.

6.3.5 Discussion

The greater extinguishing performance of the horizontal sidewall sprinkler

over the pendant sprinkler was apparently not due to a greater flow density

inside the wardrobe. At least two possibilities can be postulated for the

distinct differences:

a. The droplet size of the spray from the horizontal sidewall sprinkler was such that they penetrated the intense fire plume from the wardrobe and acheived more rapid extinguishment. (To date the droplet

sizes have not been measured for these sprinklers.)

b. The spray from the horizontal sidewall sprinkler located over the

door was somewhat parallel to the flow of combustion air into the

wardrobe. The spray may have been entrained in the combustion air

stream.

6.3.6 Impact on Sprinkler System Design

The reasons for the differences between the two types of sprinklers are

not immediately clear and need further investigation. These differences are significant in terms of the impact of sprinklers on life safety and could have

an effect on design recommendations. As the CO data, in particular demonstrate,

the prevention of flashover by the sprinkler will not in itself assure life

safety outside the room of fire origin. Limiting the generation of toxic

gases, which in these fires was dependent upon the extinguishing performance of

the sprinkler must also be considered.

In terms of possible impact on future sprinkler system and hardward design,

several points are offered based on these wardrobe tests:

a. The benefit of a fast response sprinkler for very rapid developing

(and partially concealed) room fires may not be as significant as it was for the mattress and bedding fires.

b. The droplet size and distribution may be an important performance

variable where sprinklers are used to reduce the life safety hazards

resulting from rapidly developing room fires.

135
c. The control of materials in the room such as the combustibility of

the interior of the wardrobe (or a closet) may be the only practical

solution for insuring life safety regardless of whether sprinklers

are installed in the room.

7 . REFERENCES

[1] O'Neill, J. G. and Hayes, W. D., Full-scale fire tests with automatic

sprinklers in a patient room, Nat. Bur. Stand. (U.S.), NBSIR 79-1749,

(June 1970)

.

[2] O'Neill, J. G., Hayes, W. D., and Zile, R. H. , Full-scale fire tests with

automatic sprinklers in a patient room, phase II, Nat. Bur. Stand. (U.S.),

NBSIR 80-2097 (July, 1980).

[3] Installation of sprinkler systems, Standard No. 13, National Fire Protection

Association, Boston, MA (1978 Ed.)

.

[4] Automatic sprinklers for fire-protection service, UL 199, Underwriters

Laboratories, Inc., Northbrook, IL (6th edition with revisions up to Mar

19, 1979).

[5] Minimum requirements of construction and equipment for hospital and medical

facilities, U.S. Department of Health, Education and Welfare, Washington,

D.C., May 1975 Ed and Proposed Revision, May 1977.

[6] Dinman, B. D., Journal of American Medical Association, Vol. 235, 2874-5

(June 28, 1976) .

[7] Kimmerle, G., Aspects and methodology for the evaluation of toxicological

parameters during fire exposure, Journal of Fire and Flammability/Combustion

Toxicology, Vol. 1, 4-41 (Feb. 1974).

[8] Claudy, W. D., Respiratory hazards of the first service, National Fire

Protection Association, Boston, MA (1957)

.

[9] Pryor, A. J. and Yuill, C. H. , Mass fire life hazard, prepared for the

Office of Civil Defense under Contract N228 (62479) 68665, Southwest

Research Institute, San Antonio, TX (1966).

[10] Jin, T., Visibility through fire smoke-, part 2, Report of the Fire Research

Institute of Japan, No. 33, 31-48 (1971). Part 5, Report of Fire Research

Institute of Japan, No. 42, 12-18 (1975).

[11] Jin, T., Visibility through fire smoke, main reports on production, movement

and control of smoke in buildings, pp. 100-153, Japanese Association of

Fire Science and Engineering (1974)

.

136
[12] Heskestad, G. and Smith, H. F. , Investigation of a new sprinkler sensitivity

approval test: the plunge test, FMRC Serial No. 22485, Dec. 1976, Factory

Mutual Research Corporation, Norwood, MA.

[13] Kung, H. C, Residential sprinkler test program, presentation at Factory

Mutual Research, Norwood, MA, June 14, 1979.

[14] Kung, H. C, Haines, D. M. , and Greene, R. E., Jr., Development of low-cost

residential sprinkler protection, prepared for the National Fire Protection

and Control Administration, Factory Mutual Research, Norwood, MA (Feb.

1978) .

137
138
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ALL DIMENSIONS IN METERS

Figure 2. Patient Room Floor Plan Mattress and Bedding Tests

139
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Figure 3. Patient Room Floor Plan Clothing Wardrobe Tests

140
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142
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- 350

- 300

- 250

- 200

- 150

- 100

- 50

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sprinkler actuated

Figure 6. Test N-37 Standard Pendant Sprinkler

143
90 -

0 BURN ROOM CEILING GAS TEMPERATURES

A DOORWAY SMOKE OBSCURATION =25 OD/m

CORRIDOR SMOKE OBSCURATION = .25 QD/m —* SMOKE METER LOCATION: CORRIDOR (C). DOORWAY (D)' CORRIDOR CEILING

80

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Figure 7. Test N-39 Standard Horizontal Sidewall Sprinkler

144
145
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152
Table 1. Total Weight Losses Combustible Wardrobe Tests

Sprinkler Type Test No. Weight Loss (lbs)

Pendant N-48 38.2

Pendant N-49 17.4

Pendant* N-53 40.7

Horiz Sidewall N-50 14.2

Horiz Sidewall N-51 9.4

Horiz Sidewall* N-52 9.2

*Simulated fast response sprinkler t = 21 sec.

153
APPENDIX

The dynamic heating measurements used in this presentation to characterize

fast response sprinklers were based on a proposed test called the "plunge test"

developed by Heskestad and Smith at FM. The test, which has been proposed to

determine the response time of sprinklers, is based on the assumption that in

actual fire situations, the sprinkler fusible element is primarily heated by

convection and the effect of radiation on the element is relatively small. The

dynamic heating measurement of the fusible element is expressed as the time

constant x ; where

(AT - TT ) t = g L

d(AT

L)/dt

where AT^ is the increase in temperature of the fusible element (relative to

ambient or initial temperature) and AT is the excess temperature of the gas.

t, therefore, has units of time. Hesklstad and Smith found that selected standard sprinklers when tested in a "plunge test apparatus" varied in terms of t from 100 to 280 seconds at a reference velocity, y =5 ft/sec.

154
SPRINKLER TECHNOLOGY AND DESIGN IN JAPAN

by Juzo Unoki*

August 1980

ABSTRACT

In Japan installation of sprinklers is mandatory by law for buildings where

many and unspecified persons are accommodated, high-rise buildings, dangerous

material storages, etc. The records of fire suppression by sprinklers indicate

very efficient performance of these sprinkler systems.

The heads used in these systems are designed to meet the standards which are characterized by the following : the water distribution test is to be conducted

using a single head, and the relationship between permanent and elastic elongation

is defined. The proposal on time constant as the requirement of heat response

of heads is also being discussed.

In these sprinkler systems it is not permitted to directly connect underground

supply pipe of the systems to a public water main due to the regulations, and

it is necessary to install a water reservior with fire pumps. The water

supply arrangements for the sprinkler systems in newly-constructed high-rise

buildings are shown.

Use of larger orifice sprinkler heads in dangerous material storages, etc., the

behavior of smoke and water vapor during fire suppression -by sprinklers,

prevention of water damage by interlocking with automatic fire alarm systems,

etc. are being studied in response to future needs.

* Director, Japanese Association of Fire Science and Engineering

155
. MANDATORY INSTALLATION OF SPRINKLERS

In buildings where many and unspecified persons are accommodated, e.g.,

department stores, theaters, hotels, hospitals, there is a great probability

that a lot of lives would be lost if a fire happens in the premises.

Especially, in high-rise buildings it is difficult to extinguish the fire

and rescue the occupants externally by use of Fire Department equipment

operating from ground level, and in underground shopping malls and windowless

floors hot gases and smoke from the fire could readily permeate the whole

premises. Besides these buildings rack storages and dangerous material

storages would have the greatest fire hazard. For these reasons installation

of sprinklers in these buildings over a certain floor area is mandatory by

the Fire Service Law and ordinances in Japan as summarized in Table 1.

In those buildings where many and unspecified persons are accommodated the

following premises are subjected to the codes requiring mandatory installation

of sprinklers: all floors above 11th floor; floors of l,000m2 or 1 ,500m2 or more as classified by occupancies from 4th to 11th floors; basements . and

windowless floors of over l,000m2; buildings over 6,000m2 in total floor area except those including different occupancies; underground shopping malls over 1 ,000m2. In addition all floors above the 11th floor of all buildings,

rack storages over 10m in ceiling height and over 700m2 in total floor area concurrently, buildings where dangerous materials or hazardous materials, etc. are stored or handled in excess of the predetermined amount are subjected

to mandatory installation of sprinklers.

In Japan the mandatory installation of sprinklers is applied to those buildings

constructed before the regulations took effect, not to mention newly-constructed

buildings. The number of buildings where installation is mandatory is returned

as 7,551, of which 6,551 buildings have finished installation, and the completion

1)2)

rate is 86% in the whole country as of March 31st 1979. ' ; Because there

are many cases in which persons concerned with the buildings must bear much

expenses when they install sprinklers in existing buildings, they are given

facilities for the reduction of taxes and the loan by financial institutions

associated with the government.

Sprinkler heads, alarm valves, etc. used in these buildings must be approved

by Japan Fire Equipment Inspection Corporation which has given official

approvals to 1,272 thousand sprinkler heads and 7 thousand alarm valves during

one year from April 1979 to March 1980.

156
It is important, for the effective operation of sprinklers in case of fire

to maintain equipments in satisfactory condition. Accordingly qualified

persons should inspect and repair the equipments twice per year and report

the results to Fire Department once per year in buildings where installation

of sprinklers is mandatory based on the Fire Service Law and ordinances in

Japan

.

SPRINKLER PERFORMANCE IN FIRE SUPPRESSION

3) According to Watanabe's research ' the number of sprinkler heads operating

in fires in Japan is as shown in Fig. 1 . The data have been obtained from

records of sprinkler operating in about 100 fires, and the following is found

from this figure. The curve I which shows the sprinkler performance in

Japanese buildings is below the curve IV which shows the performance in USA.

That is, the number of sprinkler heads extinguishing or control ing fires in

Japanese buildings is less than those of USA.

This is probably due to the following factors. The first factor may 'be the

lower average fire hazard of occupancies compared with USA where there are many installations of sprinklers in factories, warehouses, etc., because

occupancies where installation of sprinklers is mandatory in Japan are determined based on life safety above all things. The second may be the

smaller area and lower ceiling height of rooms. Besides the discharge density

of sprinklers mentioned below and the water distribution of sprinklers

mentioned in the next chapter may be related, too.

In Japan the provision of design discharge density in Japanese regulations is

as follows except special buildings, e.g. rack storages. The discharge rate

of a 15mm nominal orifice diameter sprinkler head should be more than 80 J?/min.

per head (at minimum head pressure 1 kgf/cm2, when 10 to 30 heads discharge

simultaneously classified by occupancies and structures of buildings). The

sprinkler spacing should be determined in such a way that all floors will be

covered by circles whose centers are just under heads and radii are 2.3m.

It is estimated from these provisions that the maximum coverage per head is

10m^ and so the minimum design discharge density is 8 mm/min. This density

is higher than 4 mm/min. required in USA Light Hazard Occupancies, and similar

4) 5) to 10 mm/min. specified in New York high-rise buildings . The duration of

discharge is 20 minutes.

157
On the relationship between discharge density and extinction time, Takahashi 6 ^

gives eq. (1) by dripping water slowly on the upper surface of wood crib. An example of its results is shown in Fig. 2.

te = () P

" i ' (1)

where te = extinction time, min.

No: number of layers of crib

P : water application rate, //min.

c< : function of the weight loss of cribs before water application

m, n: constant (m > n ~ 0.5)

That is, the extinction time is short when the water application rate is large.

On the relationship between water discharge rate and the amount of water required

for extinction, Kida^ gives eq. (2) by discharging water from spray nozzles

on wood crib fires whose weights are 0.5 to 30 kg. An example of its results

is shown in Fig. 3.

Q = 0.9 (GV)

°' 6 (2)

where Q: amount of water required for extinction, £

G: weight loss of cribs before water application, kg

V: burning rate of cribs before water application, kg/min.

In this case the amount of water required for extinction is not affected by

the water discharge rate.

Nakakuki 8

^ investigated the effects of water sprays, especially air entrainment

by the spray discharge on the extinction of various solid and liquid fuel fires,

and also the effect of type and pile arrangement of solid combustibles in an enclosure on the growth of fires and so the response time of sprinkler heads.

3. TESTS ON SPRINKLER HEADS

The test method of sprinkler heads are prescribed in the regulations and

standards based on the Fire Service Law in Japan. A few of them which have

been amended recently or will be amended in near future are presented as follows.

3-1 WATER DISTRIBUTION

In Japanese hotels and hospitals there are many small rooms and closets, many

of which are protected by one or two sprinkler heads. The water distribution

158
test was formerly conducted using four heads in Japan as in USA. However,

there were some cases in which the water distribution was good when discharged

from four heads simultaneously but not good when discharged from a single head.

In the latter cases there was only a little water distribution onto the area directly under the head or in the direction of arms of a pendant type head.

If such one or two heads would be installed in a room, there would be an area

not to be covered by sprinklers and the effective protection could not be

expected. Therefore, the standards were amended in 1976, and since then the

water distribution test has been conducted by using a single head.

It was formerly prescribed in standards that the head pressure for the test

should be 1 kgf/cm2. Many high-rise buildings were lately constructed and

their sprinkler systems were divided into several zones, each having pump or

tank. Therefore, there was a considerable head pressure difference between top

and lowest floors of the zone. If such heads showing a small coverage under

high head pressure were installed in the lowest floor of the zone, discharge

densities near wall or in the middle of four heads became smaller. Therefore,

the standards were amended in 1976 to require that the water distribution test

be conducted under head pressure 1 to 10 kgf/cm^.

The apparatus of the water distribution test for standard sprinklers is shown in

Fig. 4 and the following are required under head pressure 1 to 10 kgf/cm2.

(1) The average discharge density at every distance from a sprinkler head should

be more than the value shown in Fig. 5, where the average discharge density

is estimated by averaging the amount of water distributed to measuring pans

on each of 10 concentric circles whose centers are located just below the

sprinkler head.

(2) At least 60% of total discharge should be distributed within a circle with

a radius of 3m and its center located just below the sprinkler head.

(3) The difference between the amount of water distributed to measuring pans on each concentric circle should be small.

Examples of water distribution of two different types of sprinkler heads

used today in Japan are shown in Fig. 6. Examples of heads whose water

distribution is not good are shown in Fig. 7, in which it can be seen that

the amount of water distributed just under the head is small or the coverage

of a head is small under high head pressure. In both figures those of an ordinary pendant type heads are shown on the left and those of a multi-nozzle

type heads, on the right. The latter is a specific type head which is

manufactured only in Japan and discharges water through several nozzles

provided in its side wall. These data have been obtained by Japan Fire

Equipment Inspection Corporation.

159
3-2 STRENGTH OF FRAMES

In Japanese standards the strength of frames is required as follows to maintain the operating force of sprinkler heads for a long time. The

permanent el ongati on of a frame shown when the frame is subjected to twice the

service load in the axial direction of the head should be less than 50% of the

elastic elongation shown when the frame is subjected to the service load.

This relationship is shown in Fig. 8 and the difference between elastic and

permanent elongations keeps the operating force of the head and stops water

leakage from a orifice during the service life of the head.

In Japan it was formerly determined that the permanent elongation of a frame

should be less than 0.1% of the distance between the load-bearing points of

heat sensing element when the frame is subjected to twice the service load,

but the relationship between the permanent and elastic elongations was not clear in this case. Therefore, the above-mentioned provision has been noted

on the standards amended in 1976.

3-3 HEAT RESPONSE

Under the existing Japanese standards, a sprinkler head is required to operate within the response time classified by the nominal temperature when

placed in a test oven where the temperature rise follows a time-temperature

relationship as shown in Fig. 9.

But the actual response time of the sprinkler heads installed in buildings

is determined mainly by the cumulative convection hea4 transfer. It may

therefore be worth while considering to adopt a hot air wind tunnel test

for the sensitivity test of a head as in the case of a heat detector.

9

Oshikawa ' conducted wind tunnel tests using some existing sprinkler heads

of fusible link and glass bulb type. One of these results is shown in Fig. 10.

In this case test sprinkler heads were set in hot air flow facing their bottoms

to the flow direction. The velocity of the flow was constant (2.5m/s) and

the temperature of the air was raised linearly at a constant rate (50°C/min)

from the same temperature as the head temperature prior to the test. The

head temperature prior to the test were kept at the maximum permissible

ambient temperature (the maximum permissible room temperature not to cause

gradual weakening of heat sensing elements). K in the figure is the time

constant of the heat sensing element and estimated from eq. (3).

160
to Tm - Ta = ~H [ to - K (1 - e

" k

) J (3)

where Tm: nominal temperature of heads, °C

Ta: initial temperature of heads and air flow, °C

N : rate of rise of air flow temperature, °C/min.

to: response time of the head, min.

K : time constant of the heat sensing element, min.

From Fig. 10 the following findings can be noted. So far as the above-mentioned

hot air wind tunnel tests are concerned, the time constant of heat sensing

elements are mostly situated between 2 and 4 min. in fusible link type, 4 and

7 min. in glass bulb type: As a rule the smaller the time constant is, the more sensitive the sprinkler is, and the quicker it responds to a fire.

Therefore, heads with small time constant and rather higher nominal temperature

may be better for the reliable detection and early suppression of a fire.

From this point of view, amendment of the standards on the time constant of

sprinkler heads is desired.

WATER SUPPLIES FOR SPRINKLER SYSTEMS

As water sources of sprinkler systems fire pumps are generally used besides

gravity tanks. In Japan it is not permitted to directly connect underground

supply pipe of sprinkler systems to a public water main due to the provision

of Public Water Law, and therefore a water reservoir should be installed with

fire pumps. This reservior capacity is required to ensure a minimum discharge

duration of 20 minutes to 10 - 30 heads determined by occupancies and structures

of buildings. If it is desired to commonly use the water source for service

and sprinkler systems, a minimum available water capacity for sprinkler systems

must be secured by means of determining a lowest water level for service water

systems by a water level gage, e.g. electrodes, as shown in Fig. 11. It is also necessary to install a testing equipment of discharge capacity as shown

in Fig. 12 to test the fire pump performance.

Sprinkler heads are required to have the prescribed water distribution at

1 - 10 kgf/cm^ head pressure in Japanese standards as mentioned above.

Accordingly the water supply arrangement in high-rise buildings must be designed

in such a way that the head pressure will be less than 10 kgf/cm^ on the

operating of one head and more than 1 kgf/cm2 on the simultaneous operating

of 10 - 30 heads.

161
An example of the water supply arrangement for sprinkler system in a high-rise

building equipped with booster pumps in intermediate floors is shown in Fig. 13. This building in Tokyo is 60 stories in height with a 4-storied basement and

a 3-storied tower, and the area of its standard floor is 3,105m2. The floors

equippeo w i tn pumps ana Tea uy pumps are as TO 1 1 OWS

.

Pump Floor equipped Floor fed

Main pump 3rd basement 4th basement - 14th

1st booster pump 21st 15th - 35th

•2nd 42nd 36th - 56th

3rd 1st of tower 57th - 3rd of tower

Pressure maintenance pump

ii ii

In floors from 4th basement to 56th floor, when a sprinkler head operates by a fire,

the alarm valve in the floor of the fire origin opens by pressure difference

from the intermediate tank, the pressure switch for pump start on the alarm valve

is actuated, and so all pumps up to the floor of the fire origin begin to operate

at the same time.

In floors from 57th floor to 3rd of tower, when a sprinkler head operates by

a fire, pressure of the pressure tank connected to the 3rd booster pump and kept

usually constant by the pressure maintenance pump drops, the pressure switch

for pump start on the pressure tank is actuated, and so all pumps begin to operate

at the same time.

An example of the water supply arrangement for sprinkler systems in a high-rise

building equipped with gravity tanks is shown in Fig. 14. This building in Tokyo

is 54 stories in height with a 4-storied basement and a 3-storied tower, and

the area of its standard floor is 2,629m2. This system is divided into 4 zones fed by gravity tanks and a zone fed by a pump. A gravity tank on the 54th

floor has a capacity of 72m3 and additional gravity tanks on the 40th, 27th and

14th floors have respectively a capacity of 15m3.

FUTURE PROBLEMS

1 LARGER ORIFICE SPRINKLER HEADS

Because installation of sprinklers is mandatory mainly in the aspect of life

safety in Japan as mentioned above, sprinkler heads of 15mm nominal orifice

diameter are standardized to be suitable for buildings where many and unspecified

162
persons are accommodated. These standard sprinkler heads are used for

protection of dangerous or hazardous material storages, etc., as well,

in which case satisfactory protection can only be achieved by reducing

the area allocated to one head or increasing the duration of discharge

with these heads. In view of the increase of storage size and commodity

variety, however, studies are being made with respect to use of larger

orifice sprinkler heads, e.g., 20mm nominal size head, which is capable

of discharging large drops penetrating through severe fire plume.

5-2 BEHAVIOR OF SMOKE AND WATER VAPOR SUPPRESSION WITH SPRINKLERS

When the fire has been suppressed by sprinklers, the burning rate decreases

and so the smoke generating rate surely decreases, too. But simultaneously

a large amount of water vapor generates, the ceiling smoke layer falls near floor, the visibility in the room reduces, and so those may have a bad

effect on the escape of occupants. Regarding vapor generation resulting

from water application, Takahashi reported that when wood crib fire were suppressed by water spray, the density of generating vapor increased to

a maximum value and afterward decreased again, with the increase of the

water application rate. On the other hand the density of smoke and vapor

in actual-scale fire tests was measured by light path maters, but any

conclusion has not yet been reached.

5-3 PREVENTION OF WATER DAMAGE

Sprinklers are very effective on the suppression of a fire in its early

stage, but it is strongly required especially by department stores, etc. that water damages be limited to a minimum extent. However this requirement

is not always satisfied as they must manually close the stop valve near the

alarm valve to stop the water discharge after the extinction. In Japan

automatic fire alarm systems are mostly installed in buildings where

installation of sprinklers is mandatory. And so it may be rather easy to install preaction systems or cycling systems in these buildings by the

interconnection of above-mentioned two systems. The future study including

the amendment of regulations is desired.

ACKNOWLEDGMENT

The author would like to thank Messrs. Y. Yahazuno, A. Watanabe, N. Jiromaru

- Fire Defence Agency, T. Nakajima-Formerly Fire Defence Agency, A. Nakakuki

- Association For Safety Technics of Petroleum and Y. Yaji-Japan Fire Equipment

Inspection Corporation, for their kind suggestions and advices to make this

. report.

163
REFERENCES

1) Fire Defence Agency, White Paper on Fire Defence, November 1979

2) Tadayoshi NAKAJIMA, Situations on Installation of Fire Protection Systems

and Future Problems, Kindai Shohboh (Modern Fire Defence), April 1980

3) Akio WATANABE, Effectiveness of Active Fire Protection Systems, Kenchiku

Bonsai (Disaster Protection in Building), April 1980

4) W. Robert POWERS, Automatic Sprinkler Experience in High-rise Buildings,

Fire Journal, November 1972

5) P. NASH and R.A. YOUNG, Sprinklers in High-rise Buildings, Building Research

Establishment Current Paper 29/78, February 1978

6) Satoshi TAKAHASHI, Quantative Treatment of Extinction Phenomena of Crib

Model Fire, Bulletin of Japanese Association of Fire Science and Engineering,

Vol 29, No.l, 1979

7^ Hajime KIDA, Extinction of Fires of Small Wood Crib with Sprays of Water and

Some Solutions, Report of Fire Research Institute of Japan, No. 36, March 1973

8) Atsushi NAKAKUKI and Masai chi TAKAHASHI, Extinction of Fires with Water Sprays

in Compressed and Oxygen-enriched Atmosphers, Report of Fire Research

Institute of Japan, No. 35, March 1972

9) Sataro OSHIKAWA, Sensitivity Tests of Automatic Sprinkler Heads, Technical

Report of Japan Fire Equipment Inspection Corporation, No.l, 1977

10) Satoshi TAKAHASHI, Steam generated by Fire and Extinguishing-I , Report of

Fire Research Institute of Japan, No. 43, March 1977

164
Table 1. Buildings where installation of sprinkler systems is mandatory

Area where installation is mandatory Situations on Installation,

2) as of March 31st, 1979

Occupancies

i

Ocl It. I u 1 standards

! Basement, j Floors

windowless ! from the

floors ; 4th

! to the

i M tn

| floor

Floor

above

the 11th

floor

•Number of

buildings

where

installation

is mandatory

Number of

bui 1 dings

where

installation 1 has been

finished

r Department

j stores Retail

! stores , etc.

I

\ Floor

- over

; 1000m2

i

i

1804 1703

j Cabarets

,

Amusement

halls , etc. Building over

6000m2

in total

379 338

: Theaters

,

I Public halls,

1 etc.

i

Floor over

1000m2

377

! 301

j

Restaurants

,

etc.

f 1 oor

area except

All 33 26

Hotels, etc. singlestory

Floor

over

: 1500m2

644 404

Hospitals

,

Welfare

Premi ses

,

Kindergartens

,

etc.

building

1040 692

Special

bathhouse,

etc.

~2

0

Buildings

including

abovementi oned

occupancies

Floor,

incl uding

abovementioned

occupancies over

3000m2

Floor

over

1000m2

: or

; 1500m2

! on

j occupanj cies

2151 1910

Underground

I shopping

! malls

Building

over

1000m2 in

total

f 1 oor area

Total

55 52

6485 5426

165
In addition to above-mentioned occupancies, they should install sprinkler

systems in the following areas.

1) All floors above the 11th floor

2) Rack storages, over 10m in ceiling height and over 700m2 in total floor

area.

3) Stages, having area over 300m2 in basement, floor without windows or floor above the 4th, and over 500m2 in other floors.

4) Buildings where larger amount of dangerous materials, hazardous materials

etc. are stored or handled in excess of the predetermined amount.

166
1.0 T?^T i

1— 1 1 1—I—r—i—

• \ \ \\ \ Vx A

\ X\

1^,

i

^

\ \ \\

——i

1 1—i—i—i—

-

: "v.

i

i i ] i i i 1

TTT > \

. l

0\ n

\N\

\

i i i i i i

) 3 5 7 10 30 _ SO 70 100

n

Fig.l : q(n), Rate of fires suppressed or extinguished, in which N or more sprinkler heads operated.

I : Buildings in which the installation of sprinkler is mandatory

based on regulations in Japan (N=60).

II : Spinning mills in Japan (N=36).

m : I + H (N=96)

IV : USA

where N is the number of premises

167
Fig. 2: Extinction time vs the water

appl ication rate.

I. 32x33-6x8 H. 32 x 33-6xl2

where the dimensions of the sticks

and cribs are presented as (stick

thickness) 2 x (stick length)-(number

of sticks per layer) x (number of

layers).

Symbols (O, A etc. ) show results

correspond to the weight loss ratio

of cribs before water application.

Fig. 3: Variation of quantity of solution

required to extinguish model fire

with the value G.V.

Fig-(a) 5 (b), and (c) show results

correspond to cribs composed of

sticks of thickness 1.7, 2.5, 3.5 cm, respectively.

A Water discharge rate 0.8 iymin.

0 Water discharge rate 1.3 ^/min.

0 Diammonium Phosphate 20wt%

discharge rate 0.8^/min.

168
I

7777^ //////

Fig. 4: The apparatus of water distribution test for

standard sprinkler

169
Symbol A B

Nominal orifice

diameter (mm)

20 15

A

B

_i u '

i i I i 50 100 150 200 230 250

Distance from the center of a sprinkler head (cm)

.5: Minimum discharge density curve
Distance from the center of a sprinkler Distance from the center of a sprinkler

head (m) head (m) An example of pendant type An example of multi-nozzle type

Fig. 6 : Examples of the discharge density curves of sprinkler heads used today

CM -—

E CM

Distance from the center of a sprinkler head (m) Distance from the center of a sprinkler head (m) An exmaple of pendant type An example of multi-nozzle type

Fig. 7 : Examples of the discharge density curves of sprinkler heads which don't

comply with the standard

171
Permanent set

'Elongation

% so

s0)Ql 0 E

O)

2 3 .. 4 5 . 6 7 8 P 10 —time (min.)

Fig. 8: Requirement for the

strength of sprinkler frames

Fig.9: Temperature-time curve in

testing oven of sprinkler heads

so

20

3

<5 1 h

u

F

I f

7 / «/

/

** f

/

Tm: Nominal operating

temperature

Ta: Maximum permissible

ambient temperature

o : Fusible link type

x : Glass bulb type

'operating time (min.)

Fig. 10: Operating performance of sprinkler heads in

wind tunnel test with hot-air wind tunnel

172
Gravity tank

^1

To service water system-.

Electric power

Water level

gage

(Electrodes)

To alarm valve

Pump for

service

.water MhHP>-i (p

Maximum

capacity

system

Fire pump

avai lable

for servicle

Mi feet—*-

wter

wat£|"

mmum

for

TM"^valve^TM

available water capacity

sprinkler system

Fig. 11: Example of the dual use of water sources for service and sprinkler

system

Priming water tank

Water supp ly pipe /Escape pipe

Overf 1 ow

Orifice

-cxi- Valve in open position normally

Valve in closed position normally

1 Priming wa iDrain pipe

tep-kpipe t

Water

reservoir ft i

Testing equipment of discharge

capacity

Fig. 12: Testing equipment of the discharge capacity of fire pump

173
Pressure maintenance Pressure

tank 3rd booster p ump Water supply'

pipe

Intermediate

tank

Water supply, pipe

Water supply pipe

Water reservoir

Drain yDrai n

Fig. 13: Water supply arrangement for sprinkler system in high-rise building

(Booster pump system)

174
Water supply

pipe Gravity

tank 72m

» * » A A

54F

47F

46F

15m

3

15m

5

15m

3

Fire Department connection

_^ * A A 28F

27F

t—r—

a

AAA 15F

14F

AAA

A A A _Q AAA

IF MB1F

B1F

B2F

B3F

Fig. 14: Water supply arrangement for sprinkler system in high-rise building

(Gravity tank system)

175
ADVANCES IN RESIDENTIAL SPRINKLERS

by

Hsiang-Cheng Kung

Factory Mutual Research Corporation

Norwood, Massachusetts

October 15-17, 1980

176
ABSTRACT

Sprinkler performance as affected by sprinkler link sensitivity, link

temperature rating, and water distribution has been investigated in several

typical flame- initiated residential fire scenarios.

Commercially available sprinkler links representative of the most sensitive

on the market were employed for sprinkler activation. It was demonstrated that

links considerably more sensitive than the commercial link are essential in

providing adequate protection in residential fires.

In the ventilated living room fire tests with combustible walls and ceiling,

the fire was fast developing and highly challenging. Adequate water application

to the corner of the room, where the fire source was located, and to the walls

was found to be critical in controlling such a fire. The required sprinkler

operation conditions have been determined in terms of sprinkler water distribution associated with a link five times more sensitive than the commercial link.

177
ACKNOWLEDGEMENTS

The work was supported by the United States Fire Administration (USFA)

under Grants No. NFPCA 76054 and USFA 79019 and monitored by Mr. Harry Shaw

USFA.

178
I INTRODUCTION

The statistics on 1978 fires published by the U.S. Fire Administration show

that residential fires account for 77 percent of civilian fire fatalities,

46 percent of dollar loss, and over 50 percent of fire-fighter injuries^. It

is evident that residential fires are our nation's number one fire problem.

For over 100 years, attempts have been made to reduce fire losses. Loss

experience has provided evidence that sprinkler systems have significantly con- tributed to reduction of fire losses. In the 1860's, before automatic sprinkler systems appeared, annual fire losses at Factory Mutual insured properties

averaged over 30 cents per $100 of insured value. Later, as sprinklers became

installed in industrial and commercial properties, the figure dropped steadily

(2) to a level of 2 to 3 cents per $100 in recent years . Since the introduction of sprinklers, fire tests have been conducted ex- tensively to determine required sprinkler operation conditions for industrial

fire protection in terms of water discharge density (water discharge rate in gpm

2 in ratio to the designed coverage area in ft ), sprinkler spacing, and sprinkler

link temperature rating (link fusing temperature) . The emphasis has always

remained on industrial applications.

A National Fire Protection Association (NFPA) Standard on residential

(3) sprinkler systems (NFPA 13-D-1975) has been available since 1975 . However,

NFPA 13-D, resulting from relaxation of the industry-oriented sprinkler standard,

produces a system too costly to be. widely installed. Furthermore, the adequacy

of protection provided by commercial sprinklers in accordance with the NFPA

13-D Standard has not been evaluated sufficiently in realistic residential fire

tests. Thus, sprinklers, the most effective means yet devised for fire suppression, are still limited almost exclusively to the protection of industrial and

commercial properties.

Due to the low ceiling height and compartmentation in residental buildings,

the hot ceiling gases generated by a fire tend to descend quickly below eye

level. It is vital that the sprinkler link be sufficiently sensitive to respond

to the fire at a sufficiently early stage to maintain a survivable environment

in the room of fire origin throughout the fire.

Standard commercial sprinklers are designed for achieving fire control with

several sprinklers operating at approximately 10-ft by 10-ft spacing. The voids

179
in the water distribution pattern of a spray usually presented behind the arms

of the sprinkler frame may be filled up by adjacent sprinkler sprays. However,

in residential fires, the effective control of fire by sprinklers often depends

on a single sprinkler operation in the room of fire origin. It is essential

that sprinkler water distribution tend toward uniformity in angular distribution, so that, even if a fire starts behind the arms of the sprinkler frame,

adequate amounts of water can still be delivered to the fire source. In addition, combustible items such as sofa, chair, bureau, and drapes are often placed

close to or against the walls. A residential sprinkler is required to protect

the furniture at the periphery of the room and even the combustible walls. The

NFPA 13-D Standard permits the use of standard sprinklers in residences to cover

a 16-ft x 16-ft floor area at approximately 25 gpm water discharge rate. Most

standard sprinklers throw little water to the upper portion of a wall which is

more than 6 ft from the sprinkler. New sprinklers with water distribution

sufficient to protect the walls must be developed.

In 1976, the U.S. Fire Administration began to sponsor several programs in

the area of residential fire suppression systems. In one of these programs,

Factory Mutual Research Corporation (FMRC) has been engaged in evaluating

sprinkler performance in residential fire tests. In the first phase of this

(4)

program , a common residential fire scenario was simulated, a cigarette

dropped into the crevice of a couch in the living room, with subsequent initiation of smoldering and eventual transition to flaming fire. There were no combustibles in the test room other than the couch; windows and doors were

closed. Up to the time of flaming, the major burning areas were on the cushion

and the bolster of the couch and the fires had developed rather slowly. The

fire was exposed and could be reached by the sprinkler spray. The required

discharge rate to control such a fire is quite small.

The second phase of FMRC's program is concerned with flaming-started

fires . In these tests, several typical fire scenarios were selected. The

second phase of the program was designed to investigate sprinkler performance

as affected by sprinkler link sensitivity, link temperature rating, and water

distribution. In this paper, only some of the important results from the

second phase are presented.

The information gained in this program has served as a guide for the

sprinkler industry in developing residential sprinklers. The research results

180
of this program will provide a basis for new installation standards for residential sprinkler systems and will also lead to new evaluation standards for

residential sprinklers for approval and listing by recognized laboratories.

II TEST VARIABLES

The fire tests were designed to investigate sprinkler performance as affected

by sprinkler response time, water discharge rate, and water distribution in various typical flame-started residential fires.

The response time of a sprinkler in a fire depends on 1) the gas velocity

and gas temperature histories (fire development) adjacent to the sprinkler, and

2) the sprinkler link sensitivity and its temperature rating. The link sensitivity is expressed by its time constant, defined as the rime required for the

link to reach an excess temperature (temperature above initial temperature of

the link) which is a fraction, 0.632, of the excess gas temperature in a con- stant-velocity, constant-temperature gas stream. The time constant depends

predictably upon gas velocity and is independent of gas temperature^. The

time constants of the sprinkler links and the simulated sprinkler links used in

(6) this program were measured in a hot air wind tunnel at 7.4 ft/s air velocity and 367°F temperature. All the time constants cited hereafter are referenced to a velocity of 7.4 ft/s.

Results of six fire tests are presented to illustrate the effects of sprinkler link sensitivity, link temperature rating, and water distribution on sprinkler performance. The six tests consist of a nonventilated small bedroom fire,

two ventilated living room fires with noncombustible walls and ceiling, and

three ventilated living room fires with combustible walls and ceiling.

In the small bedroom fire test, a commercial 5/16-in. orifice diameter

sprinkler was used, discharging 4.3 gpm covering 12.3 ft x 8.8 ft floor area. The sprinkler was activated by a commercially avaiable sprinkler link representative of the most sensitive on the market. The time constant of the commercial link used was 73.9 sec. In the two ventilated living room fire tests with noncombustible walls and

ceiling, the same commercial 5/16-in. orifice sprinklers were used. In one of

the two tests, commercial links were used for sprinkler activation; in the other

test, simulated sprinkler links with much higher sensitivity (time constant = 16.9 sec) were employed for sprinkler activation.

181
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jjo

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re c

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a

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i-l o 3 O

60cH E m > o

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O

hJ Pi

SO

OO

QJ I C u co >,

re - jj u c OOICJ CO

re -

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In the three ventilated living room fire tests with combustible walls and

ceiling, two different types of manufacturer's prototype sprinklers were used.

Both manufacturer's prototypes were activated by links with a 15.1-s time constant. The sprinkler variables of these six tests are summarized in Table I.

Figure 1 is a photograph of the three sprinklers used.

Ill TEST SETUP

3.1 TEST FACILITY

The fire tests were conducted in one of FMRC's test buildings in Norwood,

2 2 Massachusetts. The building contains a 741 ft apartment area and a 139 ft

instrument room. The ceiling height in the apartment area and instrument room is uniformly

8 ft. With the exception of the north half of the living room, the ceiling was constructed with 2-ft x 4-ft Armstrong "Fire Guard" ceiling panels suspended

from the beams of the building structure. Figure 2 shows the layout of the test

apartment. Wall partitions are 5/8-in. gypsym boards framed in "Unistrut"

channels (Unistrut Corporation) . All the living room fire tests were conducted

in the living room area of the test apartment. During all tests, the doors to

the instrumentation room (close fitting) , the observation room (11/16-in.

undercut) , and the bathroom were closed. During the ventilated living room fire

tests, two windows in the north wall and the entry door were fully open. For

the small bedroom fire test, a wall partition was erected 8.8 ft from the north

wall in the living room to convert the northern area of the living room into a simulated small bedroom. During the bedroom fire test, the windows at the north

wall and the door in the partition wall were closed.

3.2 FURNISHINGS

Scale layouts of the furnishings with location coordinates for the smallbedroom fire, and living room fire tests are shown in Figures 3 and 4 respectively. Full descriptions of the small bedroom and living room furnishings are included in Tables II and III. In the living room fire tests, the window curtains were pulled aside as shown in Figure 4. The dimensions and positions of

the window openings are also shown in Figure 4.

For the small-bedroom fire test, a suspended ceiling was made of 2-ft x 4-ft combustible ceiling panels (297C Grenoble Temlock, Armstrong Cork Corporation) , 1/2-in. thick, consisting of loblolly pine, oak and cornstarch. Plywood

183
1 2 3

(1) commercial 5/16- in. -orifice sprinkler

(2) manufacturer's prototype #1

(3) manufacturer's prototype #2

FIGURE 1 PHOTOGRAPHIC VIEW OF TEST SPRINKLERS

184
23'-2"

lO'-B"-

> <~ II 12-6

Observation

Room

6.6ft 2 Window

Observation

" Window

!6'-9"

38'

Living room

Bathroom

*-3M

Closed !

Closed

i /

Hall

30x80

^oor

6'-3"

13'

Closed

Observation

Window

instrument

Room

Li

Closed

Kitchen

Entry

8'

P

x 60

I m H 7-5

FIGURE 2 TEST APARTMENT FLOOR PLAN

185
147

T

2d'

31" -

.^Plywood

if Paneling

ITSprinkler 73"

CP

42"i

2 r-^

It

« *

*NJT — C^Dummy Sprinkler 105 '/."

o

|Door(Clo>tdf. 1 1

B

M6,L+-30"H

| lqnition>

r>20

Plywood Paneling

FIGURE 3 FURNISHINGS IN SMALL BEDROOM

186
NORTH WALL

zzzzzz vAAAAAj

^-Curtains

Sprinkler" *\

Dummy

Sprinkler

FLOOR PLAN

FIGURE 4 FURNISHINGS IN THE VENTILATED LIVING ROOM

187
TABLE II

FURNISHINGS IN SMALL BEDROOM

Item

Code No. of

(Fig. 4) Units Dimensions (in.) and Description

Bed B

Mattress B

Bottom Sheet B

Top Sheet B

Blanket B

Bedspread B

Pillow B

Pillow Case B

Curtains CW

(2 panels/set)

Dresser D

(6 drawer)

Chair C

Carpet CP

2

(sets)

2

39Wx79L, mate's bed, solid hardwood, 2 guided

drawers, maple finish, with mattressboard:

1 3/4-in. thick wood, covered in polypropylene

nonwoven fabric, Sears 1K6761N2

39Wx79Lx4H, polyurethane foam covered with non- woven polyester fabric, Sears LK70112N

Twin fitted, 50% cotton, 50% polyester

Sears 96K6940

Twin flat, 50% cotton, 50% polyester

Sears 96K6944

Twin size, 100% acrylic, Sears 96K8750H-543

Twin size, 100% cotton, Sears 24K14012H-561

20Wx26L polyester fill cotton cover Sears 96K5305

20Wx30L, 50% polyester, 50% cotton,

Sears 96K6945

72Wx63L, 100% cotton, Sears 24K14029H

36Wxl3 l/2Lx29H, Solid knotty pine, with hardboard back, one coat of polyurethane finish,

Sears 1K10866N

28Wx35Lx33H Pine frame, steel springs, 2-piece

polyurethane vinyl coated cushions

147Wxl05L, Indoor /outdoor olefin pile, latex

backed, Sears 37K5031-NPH-6

188
TABLE III

FURNISHINGS IN LIVING ROOM

Item

Code No. of

(Fig. 5) Units Dimensions (in.) and Description

Sofa

Chair

End table

Curtains

Carpet

Lamp

Wastebasket

B

CW

CP

L

W

12

1

1

1

83Wx36Lx25H, Body-80% cotton felt, 20% urethane foam, cushions-80% urethane foam, 20%

polyester fiber cover-herculon , J. Homestock

#201310048

36Wx36Lx39H, Blended cotton felt, 40% (cotton

liners 70%, cotton pickers 30%), polyurethane

foam 50%, cellulose fiber pad 10%, cover-vinvl,

J. Homestock #243-1-432-0

Constructed with compressed wood slab (26 in. x 19.5 in. x 1/2 in. thick) and wood studs

(1.5 in. x 1.5 in. x 19 in. high)

6 panels (40Wx72L) 56% cotton 27% rayon, 9%

acetate, 8% polyester, 6 sheer panels (40Wx72L,

1.5 oz/yd) Batiste fabric woven/100% polyester

Sears 24K4507H

96Wx96L, Indoor /outdoor olefin pile, latex backed,

Sears 37K5031-NPH-6

15 dia x 15 H, lamp shade made by Patterson

Shade Co, Style No. 2540

Model 2132, Cities Service Co., Box 826

Pittsburgh, Pa. 15230

189
panels (3/16-in.) thick were nailed to spruce studs (1 1/2 in. x 3 5/16 in.)

mounted directly to the existing north and east walls. The partition was con- structed with plywood panels nailed directly over spruce studs (1 1/2 in. x

3 5/16 in.). Photographic view of the pretest appearance of the small bedroom

is shown in Figure 5.

For the living room fire tests with noncombustible walls and ceiling,

Armstrong "Fire Guard" ceiling panels (2 ft x 4 ft x 1/3 in. thick, Model 915,

Armstrong Cork Corporation) were fastened to the 5/8-in. gypsum board ceiling m

the northern half of the living room. Instead of plywood panels, 5/8-in. thick

gypsum boards were nailed to the wood studs on the north and east walls.

For the living room fire tests with combustible walls and ceiling, combustible ceiling panels (2 ft x 4 ft x 1/2 in. thick, 297C Grenoble Temlock.

Armstrong Cork Corporation) were fastened to 5/8-in. gypsum board ceiling in the

northern half of the living room. Plywood panels (3/16-in. thick) were nailed

to the studs on the north and east walls. A photographic view of the ventilated

living room with furnishings is shown in Figure 6.

3 . 3 INSTRUMENTATION

The room of fire origin was instrumented to measure: 1) gas concentrations

of carbon monoxide, carbon dioxide, and oxygen at "eye level" (63 in. above the

floor); 2) gas temperatures at five elevations (93, 84, 63, 36, and 6 in. above

the floor) in one location; 3) ceiling surface temperature immediately above the

ignition point; 4) optical density (a measure of smoke obscuration) at "eye

level" (63 in. above the floor) ; and 5) gas velocities and gas temperatures near

the sprinklers (3 in. below ceiling level) . Figures 7 and 11 show the instrumentation plans for the small bedroom and living room fire tests. All data

signals, except optical density, were monitored by a data acquisition system

with a Hewlett-Packard 2100 S computer. Every second, the system scanned the

data channels and logged the data on a computer disk.

Carbon monoxide, carbon dioxide and oxygen were measured at a single location near the center of the room using Beckman CO, CO^, and 0^ analyzers. The

gas sample was drawn to the analyzers through 3/8-in. ID (1/2-in. OD) aluminum

tubes and Tygon tubing and then cleaned through a glass wool filter, a condenser,

and a desiccant.

190
191
FIGURE 6 PRE- TEST APPEARANCE OF VENTILATED LIVINGROOM

WITH COMBUSTIBLE WALLS AND CEILING

192
i N

I47 :

CO.COg, O2

75—

»57 '/a—

-45

Gl-G5-^

56'/g

44 ,/i"4

l9

N

11

SK (-20-

105 V

X Gas Thermocouple

+ Ceiling Surface Thermocouple

D Bidirectional Flow Probe

O Gas Sampling = Optical Density

0 Sprinkler

^ "Dummy" Sprinkler

FIGURE 7 SMALL BEDROOM INSTRUMENTATION LOCATIONS

193
147^

X Gas Thermocouple

+ Ceiling Surface Thermocouple

CD Bidirectional Flow Probe

O Gas Sampling

s Optical Density

Q Sprinkler

$ "Dummy" Sprinkler

FIGURE 8 LIVING ROOM INSTRUMENTATION

LOCATIONS

194
The delay times for the CO, C0

2

, and 0^ measurements were 16.6, 15.4, and

24.5 sec respectively. All data presented in the report have been adjusted for

delays of the sampling system.

Gas velocities in the vicinity of the sprinklers were measured 3 in. below

the ceiling using bidirectional flow probes , which sense and indicate flows

in opposite directions with equal sensitivity and are relatively insensitive to

flow deviation from probe axial direction. The probes were connected to individual

electronic manometers (Datametric Barocel) . With this system, it was possible to

measure reliably velocities down to 1 ft/sec. The locations and orientations

of the flow probe in the small bedroom and living room are shown in Figures 7 and 8 respectively.

Thermocouples, fabricated from 30-gage, chromel-alumel thermocouple wire

(inconel sheath), were used to measure gas temperatures. A vertical traverse of

five thermocouples (93, 84, 64, 36, and 6 in. from the floor) was instal]ed in

the room of fire origin (Gl to G5 in Figures 7 and 8). A 1/2-in. wide "Unistrut"

channel was used to support the five thermocouples and shield them from direct

water impingement.

Adjacent to the velocity probe, a gas thermocouple (G6 in Figure 7; G6 and

G7 in Figure 8) was placed 1 7/16 in. from the probe axis and shielded from the

sprinkler by the probe to measure gas temperature in the vicinity of the

sprinkler.

The ceiling surface temperature immediately above the ignition source

(Figures 8 and 8) was measured by a thermocouple fabricated from 28-gage chromelalumel thermocouple wire. The thermocouple was imbedded in a shallow groove

filled with Kaowool paste such that the thermocouple bead was flush with the

ceiling surface.

IV TEST PROCEDURE

A residential sprinkler system is intended to maintain a survivable environment within the fire room for a limited period of time, sufficient for occupants

to be rescued (or possibly to escape) . A period of 15 min after sprinkler

operation appears reasonable. Therefore, all tests were conducted for a period

from time of ignition to at least 15 min after first sprinkler operation.

195
Prior to each test, all thermocouples were checked; micromanometers were

calibrated and set; the optical density meter was checked; and the CO, CC^, and

analyzers were calibrated and set. Weather conditions were noted: the wind

condition, inside and outside air temperatures, and inside and outside relative

humidity (see Table IV)

.

Before each test, the flow rate for the first sprinkler operation was set.

In the living room fire test, at the time of second sprinkler activation the

total flow rate was increased to a predetermined rate.

The ignition source for the small-bedroom fire (Test SI. 2) was a full sheet

of newspaper rolled up into a ball and placed on the floor under the side of the

bed (see Figure 3 for ignition location) . The newspaper was then ignited by a match. For all living room fire tests, ignition was accomplished by an electric

match placed through a hole on the side of a plastic wastebasket 1 in. up from

the bottom. The electric match was placed near three full sheets of newspaper,

each rolled into a ball, that were placed in the basket. Above the rolled

newspapers were four bundles, each consisting of seven full sheets of newspaper

folded in half three times. The electric match was powered by 120 V/ac through

a manually operated switch.

V SPRINKLER WATER DISTRIBUTION

In order to investigate the effects of sprinkler water distribution on sprinkler performance in the fire tests, water distributions on floor and walls

were measured for the sprinkler discharge conditions employed in the test program (with the exception of the discharge condition in the small bedroom fire)

.

Since each of the sprinklers was symmetrical with respect to the plane of the

supporting arms of the deflector and also with respect to the orthogonal plane,

only the water distribution of a quarter of the sprinkler spray bounded by these

two planes was measured.

Water distribution measurements were conducted in the FMRC Hydraulic

Laboratory. For the measurement of water distribution on the floor, 64 square

water-collection pans, each having a collection area of 1 ft x 1 ft, were ar- ranged in a square matrix of 8 x 8 pans on the floor with pans touching. The

outline of the matrix of the collection pans relative to the sprinkler position

196
TABLE IV

PRETEST WEATHER CONDITIONS

Test Wind Bar Temp °F Rel. Humidity %

No. (mph; dir) (in. Hg.) Outside Inside Outside Inside Ventilation

1 N/A N/A N/A 71 N/A 81 No

2 N/A N/A N/A 63 N/A 39 Yes

3 14 WSW 29.80 46 55 73 N/A Yes

4 10 NW 29.70 48 55 63 N/A Yes

5 21 E 29.74 39 54 85 85 Yes

N/A - Not Available

197
is shown in Figure 9a. A 4-ft x 4-ft ceiling was installed 8 ft above the level

of the top edges of the pans, below an existing 10-ft x 12-ft ceiling. (Note

that the ceiling height in the fire test building is also 8 ft.) The sprinkler was installed at the center of the 4-ft x 4-ft ceiling with the deflector 3 in.

below the ceiling and with the plane of the supporting arms parallel to one side

of the matrix of the collection pans. A front view of this setup is shown in

Figure 9b. Water collected in each pan over a period of time (3 min to 15 min)

was measured in a graduated cylinder.

After completion of the floor water distribution measurements, all 64 pans

were removed and the vertical water distributions were measured at three positions on each of the two vertical planes 6 ft from the sprinkler (see Figure 10)

Three racks of collection pans were fabricated, each rack consisting of eight

pans. Rack B in Figure 10 corresponds to the wall region behind the right arm

of the chair where initial intense burning occurred in the living room fire test

Each pan has a 1-ft wide x 1/2-ft high vertical collection area; Figure 11

provides the pan dimensions. The arrangement of the eight pans on a rack with

the bottom pan positioned on the floor is shown in Figure 12. The distance

between any two adjacent collection surfaces was 6 in. The elevation of the

ceiling above the bottom edge of the bottom collection area was 7 ft 11 in.

Measurements were first made with three racks placed on one plane, the bottom

pans resting on the floor as in Figure 12. Then all the pans were moved up

6 in. to measure the water densities of the 1-ft x 1/2-ft gap areas initially

not included. The procedure was then repeated on the othogonal plane.

Figures 13-16 present the floor and vertical water distribution data of the

commercial 5/16-in. sprinkler operating at 6 gpm, the manufacturer's prototype 1 at 12 and 9 gpm, and the manufacturer's prototype 2 at 15 gpm.

The average water application density, w^, over the 25 pans represented by

the shaded area in the floor water distribution plan (Figures 13 to 16) is used

as an indicator of the amount of sprinkler water reaching the fire source in the

corner of the living room. The outer edges of the shaded area were 7.5 ft from

the centerline of the sprinkler. In the actual living room fire tests, the east

and north walls of the living room were 6 ft from the sprinkler, as indicated by

the dashed corner in Figures 13 to 16. The water collection reported outside

the dashed corner in Figures 13 to 16 is an indicator of the amount of water

198
v

10 x 12 ft. ceiling-^

13"

•19-6!

10 x 12 ft. ceiling

Sprinklert

0-60psi .\X

Gauge

Pipe going to /water pump

A 4x4ft.

ceiling

64 - I x I ft. square pans

4 in. deep

(a) PLAN VIEW

i

i

9'- 10"

8'

lOx 12ft. ^-ceiling

-—0-60 psi gauge

P'Pe4x4ft.

ceiling

9

5/4

" e

1

i i i i i i

(b) FRONT VIEW

FIGURE 9 PLAN VIEW AND FRONT VIEW OF SETUP FOR FLOOR WATER

DISTRIBUTION MEASUREMENT

199
•I9'-6

H19-6"

0-60 psi gauge

(o) PLAN VIEW

10 x 12 ft. ceiling-^

0-60 psi

gauge

9-10"

8-

4 Q

E3

8-4"QB

E3Q

I pipe

4x4 ft. ceiling

E3

E3

E3Q

E3

Hi EI

(b) FRONT VIEW

FIGURE 10 PLAN VIEW AND FRONT VIEW OF

SETUP FOR VERTICAL WATER DISTRIBUTION MEASUREMENT

.200
FIGURE 11 WATER COLLECTION PAN

FIGURE 12 VERTICAL DISTRIBUTION RACK

201
Sprinkler —

.023 .027 .025 .013 .012 .010 .012 12"

t

6

.020 .023 .025 •01 3« Ol0« tOIO

1 .010

9

.022 .022 .025 !o22 .015 .010 —t

.010

4 .010

.020 .022 .027 b27

&i .012 .012 .013

t .015

.018 .023 .027

t"

y,. 0»5 .018

j .022

» .020

.015 .017 .017 .018 .022 .022 020 .015

.012 .013 .015 .018 .018 .018 .017 .015

.010 .010 .013 .015 .018 .022 .022 .022

-6" hi2~

A 8 " C

Sprinkler-

.003

*007

.009

'.016" 022

023

.020

"61 o" _009

"004

.005

'56~3 .003

"002

95

72"

w

(0)

FLOOR WATER

DISTRIBUTION

0.015 gpm/ft

Z

Average application density

over 25 pans in shaded are^

0

"6~0~4" 3>13~ ToiT

iOI4

lobs

,007

*004|

_00_5 "6b"

.002

*002

003

002

J. 6

L5'

0

003

.006

*009

008

*00~5' 004

"oo¥

.002

~0~02 0

iooi

(b)

VERTICAL WATER

DISTRIBUTION

2

0.011 gpm/ft

w Average application density

over 5 pans in shaded area

95* A

-28 '/^H

36

12"

Ho olo OiO

ro iu

bib olo b!b 0|0 OiO O O

N Ul oi°

1

1 OjO o|o

1

Tr- Ot O

0,0

TOiO OiO

•frig)

~r. OiO OiO

g> I ->l OiO OiO O'O

OIO

-^1 -~i O O

o o

AO/

T

8|o

_j

OjO

I

72'- O o o o b b o o bjb bib o o

o o o

2

o

g

o o

00 OjOi

- 1~ o o Ik1

FIGURE 13 FLOOR AND VERTICAL WATER DISTRIBUTION MEASUREMENTS

Commercial 5/16-in. Orifice Sprinkler, K-2.Q1, 6gpm, 9psig,

For Tests 2 and 3

202
Sprinkler —

ft I ft .UI V

All .OH JUc7 -CSoj -OI2 -CMC JO«0 12" 1

6

.VI 1 fix? U3U IwO >ft?A. . ft! 9 4 Wit

I

9

.035 022 017 .020

t .027

.032 .053 .060 037 .025 .030

i .038

1 .043

.058 .057 .052 ,"033 .040 .052

i .053

t .045

.200 .097 043 .040 052 .057 .045 .033

.053 .040 .037 .037 .043 .048 .047 .040

.627 t

.028 .030 032 .035 .042 .050 055

Sprinkltr

-6

0 _

,0_2J

"61 o' 005

002

001

oof

001

"o"

0

if

0

95'

72"

•goto)

FLOOR WATER

DISTRIBUTION

0.028 gpm/ft

2

Average application density

over 25 pans in shaded area

M2-

J013 aolo

.005

,qi_3 013*

JjOOBj

005

PSA

~00~2 .ooijj_ 6

li001

00

.001 16 .001 15 L0

.024.

"oi~3 qp_8

004

.002

"062

.001

"001' 001

00T

(b)

VERTICAL WATER

DISTRIBUTION

0.012 gpm/ft

2

Average application density

over 5 pans In shaded area

-95- 1

I- 1 2-1 28 ,/2- — ojo OiO

0 !o OiO o!o

Oi O

o!o OiO OiQ OiO OiO

015

00

-is

1 1 o|o

L—

J

rvj im

1 36'

010 OiO QiO OiO bib O'O 2

0 o!b OI

OiO O lO

""1 w 05, W

•72' 8i0 0

8 8

O O b|b 0! O O

0 0 O O W I

in •

is} 01 * —

1

FIGURE 14 FLOOR AND VERTICAL WATER DISTRIBUTION MEASUREMENTS:

Manufacturer's Prototype No. 1, K-2.69, 12gpm, 19.9psig,

For Test 4

203
Sprinkler—*

.012 .015 .022 :025 .017 .012 .0)2 .012 12"' i.

6

.015 .027 .055 s037< -.017' •012- i012

t .012

9

.022 .017 .015 .017 .037 .070

l .047

I .020

.023 .043 .050 ,028 .020 .023

l .033

1 038

.033 .037 .033 .023 .028 .040

1 .043

1 .040

.177 .055 .025 .025 .037 .040 .035 .028

.063 .033 .023 .028 .033 .035 .033 .033

.017

.018 .018 .022 .025 .033 .042 .045

-6'

-90'

W

(0)

FLOOR WATER

DISTRIBUTION

0.027 gpm/ft

2

Average application dens it over 25 pans in shaded an

hiiq

0

OOi

010

61

on

.006

0041

O02

.002

obV

.001 obi

OOI

.014

.015

95'

.001 ofo"

,OJ3

iOio

(.008

006

.004

76~03

.001 1-12=.—

.002 J_6 .001

.0021 J^6" |0"

0 J_ 6 .001 _„_)__ u0

-

003

OlV

.014 ode

.005

'ooi

.002

"oof

.001 obi

lb)

VERTICAL WATER

DISTRIBUTION

w

v

- 0.012 gpm/ft

2

w

v Average application density

over 5 pans in shaded area

•95'

-2 8 72-

36*

72"

SprlnkltrOiO OlO OlO OiO

tni — Ichiro O.O

OlO

1*1 w

OiO 0|0 * ^

OIO o o NO

1

1 ojo

__L_

0

oS

to OiO OlO

rs>ir\j OiO OiO

*• i OlO

o|^

O 'O

rolro o!o OiO

o! 5 E

•72' ojo >b 6 b!b bjb o.o o o

o;S £

§ roiw * * Sjo

PIGURE 15 FLOOR AND VERTICAL WATER DISTRIBUTION MEASUREMENTS

Manufacturer's Prototype No. 1, K-2.69, 9gpm, llpsig,

For Test 4

204
Sprinkler —

1-007 oil

0.

003

A'A oiY

|p09

obY

P91

bbV

[004.

002

1003

002

-003

toof

95"

72*

tfrlnkltr

WWw Baa oia Am u<cu ij"

6

0)20 02 8 osa UOw

I nit

9

AIC 9 J046 075 *J38 AMMS 048

1 045

i 030

Aft

JO3d .082 068 a^ n .058 065 .050

t 030

4 .020

.0*2 .108 .080 080 .050 025 020 JUI?

.206 .130 DO 048 .030 025 .020 .018

.295 .175 .118 .088 062 .045 .032 .028

.142 .120 .098 068 .050 .040 030

h2-

A 1 8 C

(0)

FLOOR WATER

DISTRIBUTION

w =0.035 gpm/ft2

w =average application density

over 25 pans in shaded area

(b)

VERTICAL WATER

DISTRIBUTION

wv=0.012 gpm/ft 2 wy=average application density

over 5 pans in shaded area

95"-

L

o o

oSb bib 60O

too OlO o{o

loio |o !o "JO|0 joio fc'2

N ,N

Ol- • l" o!b bib O io ojo

_1_

•T2! 8i| 8 jfi

<a in

bjb b|o

5>|3»

b| o|o

FIGURE 16 FLOOR AND VERTICAL WATER DISTRIBUTION MEASUREMENTS:

Manufacturer's Prototype No. 2, K=3.00, 15gpm, 25psig,

For Test 5

205
which would have hit the lower portion of the walls if walls had been present

during these water distribution measurements.

If walls had been present, water collected over the 1-ft x 2.5-ft shaded

area of Rack B in the vertical water distribution plan of Figures 13 to 16

would have dripped along the plywood panel behind the chair, affecting ignition

of the walls in the living room fires. The vertical application density, w^,

over the 1-ft x 2.5-ft shaded area indicates the amount of water delivered to

protect the wall.

VI RESULTS AND DISCUSSION

To evaluate the adequacy of life-safety protection provided by sprinklers,

measurements were made of CO, CO2 and 0^ gas concentrations and gas temperature at eye level in the room of fire origin. The ability of residential

sprinklers to provide property protection was assessed by measurement of the

ceiling surface temperature over the fire source. Sprinkler response time with known link sensitivity and temperature rating

can be predicted theoretically by means of gas temperature and velocity histories

at the sprinkler. Measurements of gas temperature and velocity in the vicinity

of the sprinkler closest to the fire source were used to aid in the selection

of a sprinkler link with a sensitivity such that, at the time of sprinkler

activation, the fire would stil be in the early stage of its rapid development.

The sprinkler water distribution required to control residential fires has

been determined from the fire test results, together with sprinkler water distribution measurements.

6.1 LIFE SAFETY AND PROPERTY PROTECTION CRITERIA

6.1.1 Life Safety Criteria

Measurements of CO and gas temperature at eye level in the room of fire

origin were employed to evaluate the adequacy of life safety protection provided

by sprinklers.

Carbon monoxide has been identified as the major toxic gas in the fire

(8) environment causing fatality . The primary toxic effect exerted by CO is

to reduce the oxygen-carrying capacity of the blood. Once CO enters the body,

it combines reversibly with the chief oxygen-carrying protein of the red blood

206
cells, hemoglobin. This complex of CO and hemoglobin is termed "carboxyhemoglobin" (CO Hb) ; a 16-20 percent CO Hb saturation in venous blood will cause

(9) headache and an "abnormal visual evoked response.' The amount of CO Hb

formation in the blood depends on the concentration and exposure duration. It

(9) is estimated that a 43-min exposure at 1000 ppm, a 100-min exposure at 500 ppm, or a 400-min exposure at 200 ppm will result in a 20-percent CO Hb saturation in

blood. Estimates of "hazardous levels" reported by Yuill^^ are 1,600 ppm for

1/2 hr, 800 ppm for 12 hr and 120 ppm for 8 hr. Kimmerle^ 11 ^ reported that CO

concentration at 1500 ppm will cause death after one hour of inhalation. A con- servative criterion was selected for evaluating the CO hazard in the test program; the maximum CO concentration at eye level in the room of fire origin was required to be less than 1500 ppm throughout the entire test period, i.e., from

the time of ignition to 15 min after sprinkler activation.

Inhalation of carbon dioxide rapidly leads to abnormal breathing. As

little as 2 percent of CO2 by volume in the inspired air effectively stimulates

respiration and 3 percent doubles the lung ventilation. Inhalation of 7 to 10

(12) percent CO2 may be fatal within a short period.

The normal oxygen content of air is 21 percent. Diminishing the supply of

oxygen to 12 to 15 percent will result in shortness of breath, headache, dizziness and rapid fatigue. An oxygen supply of 6 to 8 percent will cause collapse,

with the possibility of death. (11 ' 12)

On the subject of human tolerance to heat, Kimmerle^^ reported that gas

temperatures of more than 212°F in a fire environment were capable of causing

loss of consciousness and death within several minutes. The criterion adopted

for evaluating the heat hazard in the program was that the gas temperature at

eye level should be less than 200°F throughout the test period.

6.1.2 Property Protection Criteria

Measurements of ceiling surface temperature over the fire source were used

to assess the ability of residential sprinklers to provide property protection.

Cellulosic and plastic material usually begin to pyrolyze vigorously at a temperature of about 500°F. The limit for the ceiling surface temperature

directly above the ignition point is selected to be 500°F in order for sprinkler

protection of property to be considered adequate.

207
6.2 TEST RESULTS

6.2.1 Small Bedroom Fire Test

Gas concentrations of CO, CC^ and 0^ at the 63-in. level near the center of

the room are shown in Figure 17. The maximum CO and CO2 concentrations are 1107 ppm and 1.8 percent respectively, and the minimum 0^ concentration is

16.5 percent. The CO and C0£ concentrations and 0^ deficiency were smaller than

the critical values.

Gas temperatures at three elevations, 93 in., CO in., and 36 in. from the

floor, are shown in Figure 18. The gas temperatures measured at the three

elevations reached maximum values at about the time of sprinkler activation

(2 min, 5 sec). After sprinkler operation, the voltage readings from the thermo

couples measuring these temperatures seemed to indicate that the thermocouple

beads were wetted by the sprinkler spray. The eye-level gas temperature reached

241°F at the time of sprinkler activation. In such a small room, a more sensitive sprinkler link would have been required in order to activate the sprinkler

before the eye- level gas temperature reached 200°F.

The maximum ceiling surface temperature over the ignition point was maintained below 165°F. In this test, combustible walls and ceiling were used but

were not involved in the fires.

6.2.2 Ventilated Living-Room Fire Tests with Noncombustible Walls and Ceiling

In Test 2, commercially available sprinkler links with a time constant of

73.9 sec and a temperature rating of 165°F were employed. At the time of the

first sprinkler operation, the fire was already in the very rapidly accelerating

stage, and the gas temperature adjacent to sprinkler No. 1 already reached 465 °F

The fire had spread to the full length of the curtains. The side of the chair

was burning intensely and flames were sweeping across the ceiling. Fire jumped

to the side of the sofa 1 sec before sprinkler activation.

In Test 3, simulated links with much higher sensitivity (time constant =

16.9 s) were used for sprinkler activations. Links were selected to have a sensitivity such that, as the link reached the rated temperature, 140°F, the

curtains behind the chair would have just ignited and the major burning item

would be still limited to the chair. The determination of the time constant of

such a link was based on the histories of gas temperature and velocity adjacent

to sprinkler No. 1, Test 2.

208
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The effect of sprinkler response time is investigated by comparing the

results of Tests S2.1 and S2.3 which had the same water discharge rate but different link sensitivities. CO gas concentrations, gas temperatures at eye

level, and ceiling surface temperatures are plotted in Figures 19, 20 and 21

respectively. For Test 3 the reference point of the time abscissa is the activation time of sprinkler No. 1 (at which time the simulated link temperature

increased 71°F from its initial temperature), whereas for Test 2, the reference

point of the time abscissa is the time, t^, at which the temperature of a 16.9 sec time-constant simulated link would increase by 71°F. In Test 2, the

maximum CO concentration was over 10,000 ppm, beyond the range of the CO

analyzer. The maxmimum values of CO concentration, gas temperature at eye

level, and ceiling surface temperature for Test 2 exceeded the critical values

adopted for evaluation of sprinkler performance. The results of Test 3 demonstrate that the commercial 5/16-in. orifice sprinkler activated by a simulated

link with a 16. 9-sec time constant, rated at 140°F, discharging 6 gpm is capable

of providing adequate life-safety and property protection in such a fast-growing

fire.

In Test 3, at the time of sprinkler activation, the gas temperature adjacent

to sprinkler No. 1 was only 202°F. Fire then gradually spread to the backside

of the chair and was completely shielded from the sprinkler spray. The sprinkler

spray tested was not capable of suppressing the fire and cooling the gases sufficiently, and the gas temperature reached a maximum value of 637°F, 129 sec after

sprinkler activation. It is expected that sprinklers with the same links (rated

at 140° F) in the hallway and the kitchen would also have operated.

The average water application, w

c

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area in the floor water distribution plan in Figure 13 to 16 is used as an indicator for the amount of sprinkler water reaching over the fire source in the

corner of the living room. For Tests 2 and 3, the value, w , was only

2

c 0.015 gpm/ft (Figure 13). The fire test results indicate that, in order to

suppress the fire and cool the gases sufficiently, more water is required to be

delivered to the corner of the room.

6.2.3 Ventilated Living Room Fire Tests with Combustible Walls and Ceiling

The presence of the combustible walls and ceiling added a greater fire

challenge to the sprinklers. With a low-sensitivity link, at the time of

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214
sprinkler activation the fire would have spread to the plywood panels and flames

would be sweeping across the ceiling. Therefore, it is even more critical in

such fires to have a sensitive link to activate the sprinkler when the major

burning activity is still limited to the chair than in fires with noncombustible

walls and ceiling. Furthermore, a sufficient amount of sprinkler water over the

fire source is required to suppress the fire to prevent the ceiling panels from

ignition, and adequate wetting of the combustible walls is essential to stop

fire spread from the chair to the walls.

Two dirt'erent kinds of manufacturer's prototype sprinklers were used.

The spray patterns of these sprinklers had no apparent voids behind the arms of

the sprinkler frame. Manufacturer's prototype 1, operating at 12 or 9 gpm

delivers water to the walls at a height within 1 ft from the ceiling (Figures 14

and 15). Operating at 12 gpm, this sprinkler had an application density, w , of

2 2 C

0.028 gpm/ft and a vertical application density, w , of 0.012 gpm/ft (Figure

V

2 2 14); at 9 gpm, the values of w

c and w

v

are 0.027 gpm/ft and 0.012 gpm/ft

respectively (Figure 15). For manufacturer's prototype 2, at 15 gpm, the

2 average application density, w , is 0.035 gpm/ft and the vertical application

2 c density, w^, is 0.012 gpm/ft (Figure 16).

Manufacturer's prototype 1 was investigated in Test 4. With one sprinkler

in operation, the sprinkler discharge rate was 12 gpm; when the second sprinkler

was activated, the discharge rate through each sprinkler was 9 gpm. Although

the water application density on the wall above the chair was adequate to stop

the fire from jumping from the backside of the chair to the wall, the application density over the fire source, w

c> was not sufficient to prevent the fire

source from igniting the ceiling above the fire and the plywood panels above the

windows. Damage was quite extensive.

Manufacturer's prototype 2 was investigated in Tests 5 and 6. The discharge

rate of the first sprinkler was set at 15 gpm. In both tests, only one sprinkler

was activated. An adequate amount of water was delivered over the fire source

and to the walls. The fire was controlled and the major burning was limited to

the chair.

Gas concentrations of CO, C^, and O2 at eye level for Test 4 are shown in

Figure 22. The maximum values of CO and C0~ concentrations and 0 7 deficiency

215
CARBON DIOXIDE GAS CONCENTRATION ( X VOL.)
were 9400 ppm, 8.0 percent, and 8.9 percent respectively. Based on measurements

of CO, CO2 and 0^ concentrations, the environment in the room of fire origin is

deemed nonsurvivable.

Figure 23 shows the CO gas concentrations at eye level for Tests 5 and

6. In both tests, the CO concentration had not exceeded 280 ppm.

For Tests 4, 5, and 6, eye-level gas temperature and ceiling surface temperature above ignition are shown in Figures 24 and 25 respectively. The maximum ceiling surface temperature for Test 4 exceeded the adopted critical value

for evaluation of property protection. For both Tests 5 and 6, all the maximum

values of CO concentration, • eye-level gas temperature, and ceiling surface

temperature were considerably smaller than the critical values. Therefore, a manufacturer's prototype sprinkler, activated by a 15.1-sec time-constant link

2 rated at 136°F, delivering 0.035 gpm/ft of w over the fire source in the

2 C corner of the room and 0.012 gpm/ft of to the wall above the chair has been

demonstrated to be effective in controlling such a high-challenge, fast developing fire and capable of providing adequate life-safety and property protection in the room of fire origin.

VII CONCLUSIONS

Performance of pendent sprinklers as affected by sprinkler response time

and sprinkler water distribution has been investigated in several typical,

residential fire scenarios involving flaming fire starts. A commercially

available sprinkler link, representative of the most sensitive on the market,

was employed for sprinkler activation in a nonventilated small-bedroom fire.

Due to the small room size (12.3 ft x 8.8 ft), hot ceiling gases descended

quickly to eye level. At the time of sprinkler activation, the eye-level gas

temperature near the center of the room had already reached 241°F, exceeding the

adopted critical value for eye- level gas temperature. In order to maintain a survivable environment in the room of fire origin throughout this fire, it was concluded that the sprinkler should respond at an earlier stage of the fire; in

other words, the sprinkler link must be even more sensitive than the commercially available link.

In the living room fire tests, combustibles were located in the northeast

corner of the room; fire first spread to the left side of a reclining chair, and

217
218
219

then to the curtains behind the chair. Fire on the left side and backside of

the chair was shielded from direct sprinkler water impingement. In order to

suppress such a challenging fire and cool the fire gases, considerably more

water was required over the fire source than in the small-bedroom fire. An

average water application density, w^, over a 5-ft x 5-ft floor area in the

corner of a 15-ft x 15-ft coverage area without walls was used to indicate the

amount of sprinkler water delivered to the corner of the living room. The

vertical application density, w^, over the 1-ft wide x 2. 5-ft high area on the

wall above the chair indicates the amount of water delivered to protect the wall

from igniting by the source fire.

In the ventilated living room fire tests with noncombustible walls and

ceiling, it was demonstrated that a sprinkler activated by a 16.9-sec time

constant link rated at 140°F, delivering an application density, w , of

2 ° 0.015 gpm/ft , was capable of providing adequate life-safety and property pro2 tection in the room of fire origin. However, a value of w

c of 0.015 gpm/ft was not sufficient to suppress the fire and cool the fire gases to prevent excessive

sprinkler openings in the hallway and the kitchen outside the living room.

In the ventilated living room fire tests with combustible walls and ceiling,

manufacturer's prototypes with a link of 15.1-sec time constant rated at 136°F

were investigated. The critical value of the application density, w , was found

2

C to be 0.035 gpm/ft in order to suppress the fire source in the corner and

prevent plywood panels and the combustible ceiling above the fire source from

igniting. In addition, sufficient wetting of the combustible walls was also

essential in preventing fire spread from the fire source to the walls. A ver2 tical application density, w^, of 0.012 gpm/ft on the wall from 3.5 ft to 6 ft

from the floor was demonstrated to be adequate to prevent fire jump from the

backside of the chair to the wall.

In the tests in which the manufacturer's prototype 2 sprinkler was demonstrated to be successful in controlling such a challenging ventilated fire, only one sprinkler was activated and the sprinkler discharge rate was 15 gpm covering

a 12-ft x 12-ft area. Further, the prototype discharges a rather uniform pattern

in the angular distribution so that, even if a fire starts behind the arms of

the sprinkler frame, an adequate amount of water can be expected to be delivered

to the fire source.

221
In conclusion, significantly more sensitive links than the commercial link

representative of the most sensitive on the market are essential in providing

adequate life-safety and property protection in residential fires. The required

sprinkler operation conditions for control of such a typical high-challenge,

fast-developing residential fire have been determined in terms of water distribution associated with a link (rated at 136°F) five times as sensitive as the

commercial link.

The results obtained in the program will 1) serve as a guide for the

development of residential sprinklers, 2) establish a foundation for new installation standards of residential sprinkler systems, and 3) lead to new evalua

tion standards for approval and listing by recognized laboratories.

222
REFERENCES

1. "Highlights of Fire in the United States," Second Edition, Federal

Emergency Management Agency, United States Fire Administration,

Washington, D.C., 1980.

2. "Automatic Sprinklers: Protection in New Setting," Record , vol 55,

No. 1, p 3, Factory Mutual System, Norwood, Mass., January-February, 1978.

3. "Standard for Installation of Sprinkler Systems in One- and Two-Family

Dwellings and Mobile Homes NFPA No. 13D-1975," National Fire Protection

Association, Boston, Mass., 1975.

4. Kung, H.C., Haines, D.M. and Greene, R.E., "Development of Low-cost

Residential Sprinkler Protection," Technical Report RC78-T-3, Serial

No. 22574, Factory Mutual Research Corporation, Norwood, Mass.,

February 1978.

5. Kung, H.C., Spaulding, R.D. , and Hill, E.E., "Sprinkler Performance in

Residential Fire Tests," Technical Report RC80-T-16, Serial No. 22574,

Factory Mutual Research Corporation, Norwood, Mass., July 1980.

6. Heskestad, G. and Smith, H.F. , "Investigation of a New Sprinkler Sensitivity Approval Test: The Plunge Test," Technical Report RC76-T-50,

Serial No. 22485, Factory Mutual Research Corporation, Norwood, Mass.,

December 1976

7. Heskestad, G. , "Bidirectional Flow Tube for Fire-Induced Vent Flows,"

Appendix K of Technical Report RC74-T-31, Serial No. 21011.4,

Factory Mutual Research Corporation, Norwood, Mass., July 1974.

8. Halpin, B. , Fisher, R.S., and Caplan, Y.H., "Fire Fatality Study,"

Presented at International Symposium on Toxicity and Physiology of

Combustion Products, University of Utah, Salt Lake City, Utah, March 1976.

9. Steward, R.O., "The Effect of Carbon Monoxide on Man," JFF /Combustion

Toxicology , vol 1, p 167, August 1974.

10. Yuill, C.H., "Physiological Effects of Products of Combustion,"

ASSE Journal , p 36, February 1974.

11. Kimmerle, G. , "Aspect and Methodology for the Evaluation of Toxicological

Parameters During Fire Exposure," JFF /Combustion Toxicology , vol 1, p 4,

1974.

223
B! 1 12. Biekerdorf, F.W. and Yuill , C.H. , "An Investigation of the Hazards of

Combustion Products in Building Fires," Final Report SwRI Project

No. 3-1237-3, Southwest Research Institute, San Antonio, Texas, October 1963,

13. Banford, C.H. , Crank, J., and Malan, D.S., "The Combustion of Wood, Part I,"

Proceedings of Cambridge Philosophic Society, vol 42, p 166, 1945.

14. Madorsky, S.L., "Thermal Degradation of Organic Polymers," Interscience

Publishers (John Wiley and Sons), New York, 1964.

224
Discussion of Presentations on Sprinkler Technology

O'Neill Presentation

Handa: I understand the use of fast response sprinklers which has

a large amount of water sprinkling, but I do not understand the use

of the slow response sprinkler.

O'Neill: In this paper we looked at standard U.L. listed sprinklers

which are currently available. For the mattress and bedding fires,

they were relatively slow in responding for the conditions that we were looking at and given the gas temperatures that occurred in the

vicinity of the sprinklers.

Handa: I think we are primarily talking about residential sprinklers.

In my opinion, in this case, more numbers of sprinkler heads and more

water will be more useful. I do not understand for what case the slow

response sprinkler would be used.

O'Neill: We specifically addressed the patient room arrangement of

a hospital. Dr. Kung will talk about the fast response for residential

fires later in the program.

Handa: What do you mean by slow response?

O'Neill: In terms of the thermal inertia, it is the length of time

difference from the time that the gas temperature near the sprinkler

reaches its actuation point, (the nominal actuation rating) compared

to the actual time of response. To explain further, for example in

this case with this fire the gas temperature near the sprinkler has

reached 200°C before the sprinkler actuated although the sprinkler

was rated at 74°C.

Handa: What is the relationship of the sprinklers to detectors?

Did you use detectors in the test series?

O'Neill: Yes we did. However because of the limited time on the

agenda today, I have not discussed the response or results of the

detector phase. They are contained in another report which we can make available to Prof. Handa.

225
Unoki Presentation

Quintiere: How important is the problem of disturbance of the smoke

layer by the sprinkler.

Unoki: Any obscuration by smoke would be detrimental for the escape

of the occupants. As I mentioned in my presentation, in Japan the

buildings where sprinkler systems are mandatory in order to save human

lives, they must install automatic fire alarms as well. So, up to now

the thinking has been for escape of the occupants, they would have to

depend on the automatic fire alarm system. When you have to examine

the usefulness of the sprinklers installed above the escalators, or staircases, we still have to find out if sprinklers are really helpful

or detrimental for people to escape.

Emmons: A few remarks in connection with the last question by

Dr. Quintiere may be worth noting. The effects of the sprinkler

involve two things. The water spray coming down from the sprinkler

drives the gases down with it. This tends to mix the obscuring

particles into a larger volume, a little less density perhaps, but

it increases the obscuration for a short time at least. It puts

the he fire out, but it does spread the obscuring particles. However, it also cools the gas, and when you cool the gas it contracts

and more fresh air coming in from outside. These two effects have

contradictory effects: outside it becomes a little less obscure;

inside it becomes a little worse. This makes it very complicated

to know for certain whether you are better or worse with the sprinklers.

It will also complicate the matter of fire modeling, as I believe

Dr. Quintiere was concerned with, in attempting to predict whether

sprinklers are better or worse.

Clarke: When was the date of the regulation requiring installation

of sprinklers in the buildings. Referring to you paper it was 1976,

but I may have missed it, if it was actually written down. I am impressed with the remarkable rate at which sprinklers are being

installed in buildings, in which I guess previously did not have

sprinklers

Unoki: The regulation date was roughly twenty years ago. Of course

in those twenty years this problem of installation has expanded greatly.

Before the regulations went into effect, there was some sprinklers

installed but very few. One exception, the very famous Mitsukashi

department store in Tokyo installed its sprinkler system even before War

World II.

226
Clarke: Are metal, iron piping required in all sprinklers in

Japan. Especially in retrofitting, in installing sprinklers after the

building is constructed, are lighter weight piping materials permissible

in any cases?

Unoki: A building that is mandated to install a system must use iron

piping. Neither plastic nor copper piping has been used as yet.

Benjamin: I would like to congratulate Dr. Unoki for his very fine

presentation. I now know far more about sprinklers in Japan than I did before. Two features that are used in this country are what we call water flow alarms which actually sound a gong alarm when the

water in the sprinkler is activated; and also sprinklers are required

to be tied into the alarm system so that when a sprinkler head

activates the alarm system is also activated. I wonder if the Japanese

practice also has these features?

Unoki: The building which has an automatic alarm system will sound

the alarm when the sprinkler is activated. In other buildings we recommend installation of an alarm system in the middle of the building.

There was an example, of an accident in a large storage building. In

the middle of the night a sprinkler system went off without any fire by

false alarm. The local bell sounded but it did not reach the control

center and the accident was recognized after the consumption of 30

minutes of water storage.

O'Neill: Was the need for a change in the previous sprinkler spray

distribution test, the single head distribution test, enhanced or necessitated by poor fire experience or was it justwas perceived to

be the problem with the void coverage?

Unoki: I do not believe that it was because of past fire experiences.

It was because Japanese rooms are small and each room seems to have one

or two heads. The reason the change occurred was to avoid any space

where water does not cover.

227
Kung Presentation

Handa: I am interested in how you developed the highly sensitive

link. I think you might lower the heat capacity. Is this a corporate

secret?

Kung: By reducing the mass and increasing the surface area to correct

the heating, you increase the sensitivity.

Handa: I assume the air content has very little heat. On the other

hand, the sensor is metal.

Kung: It takes much less heat to heat that element up than the

standard sprinkler link.

Emmons: What fraction of the heat actuation of the link comes from

the gas directly by convective heat transfer as opposed to radiation

from the flame? Does radiation contribute significantly?

Kung: We have not done an exercise to determine what fraction

comes from convection or what fraction comes from radiation. However, we assume that transport is by convection. Then we use the heat

transport equation to predict that link thermal response and compare

the prediction with the measured value of the link temperature. The

predictions are very close. I imagine before the sprinkler activates,

the fire is not of such a big size. The fire was about five or six

feet tall.

Unoki: I remember you said only one sprinkler head activated, but

do you have two sprinklers that you installed for the test?

Kung: In the test we installed four sprinklers.

Unoki: Are there any figures describing where these sprinklers are installed?

Kung: Yes, it is in the report.

Unoki: For your test described today, was there only one head

installed?

Kung: This was a condensed version.

Unoki: One thing I noticed in your presentation was that no measurements of smoke obscuration were mentioned. Why?

Kung: The obscuration measurments were included in the report.

Unoki: I remember in Mr. O'Neill's report the obscuration was bad.

Were similar conditions reached in your experiment?

Kung: Yes.

228
Chaiken: The prototype link that you developed had a one second or two second response; you also had a 135°F burn height capability.

What would you expect the false alarm rate to be in a house with the

heating system or out west where you have some high solar energy.

Do you have any ideas?

Kung: I think this concern has been taken care of in the new proposed

standard which requires that the fusing temperature at the link be at

least 35°F above the maximum temperatures in that locality. So, I don't really know when they would have to use 165°F temperature rating.

Quintiere: What was the nature of the distribution of the spray? Do

you feel that that has been optimized with regard to the residential

environment of a relatively small room compared to industrial sprinkler

applications?

Kung: I do not feel that the spray pattern from the phototype

sprinklers are necessarily optimized. Next week at the Annual Conference, I will shed some light on the pattern of spray distributions

found in more extensive studies.

Miyama: I assume the residential sprinkler will become popular and

the standard test for these sprinklers may become important. One

suggestion is to standarize the dimension of the test room and the

type of burning fuel material and its quantity.

Kung: I think the new approved standards, specifically for

residential sprinklers, are being developed by Factory Mutual and

Underwriters Laboratories. The sprinklers used in residences will be

only the residential sprinklers and would not be standard sprinklers.

In the approved test standards we will try to formulate some standard

fire tests to evaluate the performance of sprinklers.

Saito: From what point of view did you decide the permissible levels

of CO concentration of 1500 ppm and temperature of 200°F?

Kung: We did not mean them as permissible levels. We just chose

these values. As experts you probably could provide better values

for these.

Saito: I am glad to hear this. If these values are approved, our work in toxicity has been completed. In relation to those two factors,

CO concentration and the temperature, I believe the use of the sprinkler

usually raises the amount of humidity. The humidity is another

factor affecting human conditions. I suggest that humidity should be

taken into consideration.

Kung: I hope NBS would take this into consideration.

229
5. FIRE MODELING

230
Reprinted from JOURNAL OF HEAT TRANSFER. Vol. 102. So. 1. February 1980

C. M. Kinoshita

P. J. Pagni

Department ol Mechanical Engineering,

University of California. Berkeley. CA 94720

Laminar Wake Flame Heights

One important measure of material fire hazard is the flame height a given polymer pro- duces upon burning in a specified ambience. Six systems are considered here —two fuel geometries: wall-mounted and free standing; and three flow fields: forced, free and mixedmode. In each case, the extent of the combusting gas downstream of a pyrolyzing slab is obtained as a function of the fuel's thermochemical properties. The flow is modeled as a steady, laminar, two-dimensional, nonradiative boundary layer. The combustion is de- scribed by a single Shvab-Zeldovich energy-species equation assuming unit Lewis number

and a fast one-step overall gas phase reaction. Sumerical methods are employed due to the abrupt change in boundary conditions at the end of the pyrolyzing slab. However, an

approximate similarity solution is found for forced flow which yields explicit flame

heights. Based on these results, explicit functional fits to numerical flame heights are ob- tained for free and mixed-mode flows. Comparisons between theory and experiment indi- cate quantitative agreement. Introduction The development of laminar, forced, free, and mixed-mode convection flames above both wall- mounted and free-standing vertical burning surfaces is examined. This study is a natural extension of previous investigations of laminar combusting boundary layers [1-7). The limits of pure forced and pure free flow combustion downstream

of vertical pyrolyzing surfaces have been examined by Pagni and Shih

(4) and by Faeth and co-workers [5, 6). while mixed-mode diffusion flames adjacent to a burning fuel slab have been analyzed by Shih and

Pagni [7], The present investigation extends the analysis of mixed- mode combustion into the region above the fuel source and provides accurate explicit expressions for flame heights in all six cases considered. Good agreement is obtained with experiments. The six systems analyzed are illustrated schematically in Fig. 1. The

two geometries given in Figs. l(a ) and 1(6) are: I la ) combustion adjacent to an inert, adiabatic, vertical extension above the fuel slab, referred to as "wall-wake" or "wall-plume" combustion, and (16) combustion above a free-standing fuel slab referred to as "wake" or "plume" combustion. Three flow regimes are considered for each

geometry: (1) forced flow: £x « 1, (2) free flow: £x > 1, and (3) forced and free mixed-mode flow: £, =0(1). In each case a uniform stream

of oxidizer approaches the vertical fuel plate and reacts with pyrolyzed

fuel in a thin diffusion flame.

All systems have two regions: a pyrolysis zone where energy transfer to the fuel produces mass transfer into the flow and partial fuel con- sumption occurs, and an extended flame zone where pyrolysis ceases and the combustion process is completed. The abrupt change in boundary conditions between these regions disallows similarity; hence, numerical techniques are employed. For pure forced flow combustion, however, an approximate similarity model is developed which yields flame heights in terms of known combustion parameters. The analyses

are presented in order of increasing complexity, viz., pure forced, pure

free, and then mixed-mode combusting flow.

Forced Flow Combustion

Analyses. The boundary-layer equations which govern twodimensional, laminar flows with fast kinetics are well known, hence

the mathematical treatment is abbreviated. Making the usual Shvab-Zeldovich and boundary-layer assumptions, the continuity, momentum, and coupled energy-species equations for forced flow combustion, neglecting dissipation and radiation, are. in turn, —d d

(pu) + — \pv) = 0 dx dy

du du d I du

pu h pv — = — \u —

dx dy dv \ dy.

(1)

dj dJ

pu — + pv —

dx dy dy \ dyj

in which J is the normalized energy-species variable. The stoichi- omecry is given by an assumed single-step overall chemical reaction.

uf fuel + i>„, oxidizer — vp products + Q i.2)

where Q denotes the energy released by Vf moles of fuel in the reaction.At the pyrolyzing surface, the streamwise velocity vanishes, the enthalpy is specified and energy and fuel balances yield the transverse

velocitv and the wall fuel concentration:

and

X dh

cp L dy

pD dYf x < L 1 3) Yfw - Yft dy The boundary conditions downstream of the pyrolyzing surface, x > L depend on the specific system under consideration. For wall-wake combustion, the velocity vanishes at the adiabatic. inert wall along

with the enthalpy and fuel gradients, whereas, for wake combustion,

the transverse gradients of streamwise velocity, enthalpy, and fuel are zero along the axis of symmetry as is the transverse velocity. In

FLAME SHEET

Contributed by the Heat Transfer Division tor publication in the JOURNAL

OF HEAT TRANSFER. .Manuscript received by the Heat Transfer Division October 17. 1979.

Fig. 1 System schematic of steady, laminar, mixed-mode combustion above

a burning vertical fuel slab: (a) wall-wake combustion; (b) wake combustion

104 / VOL. 102, FEBRUARY 1980 231 Transactions of the ASME
all instances, the streamwise velocity, enthalpy, and oxidant approach

their prescribed values in the tree stream. The following dimensionless variables are appropriate: X = - , Y =

V =

Re,

pv +

JO Pa,

Jo

dp

14)

\ -'o a.t

in which Re^ = u.^/k. is the slab Reynolds number. Assuming constant Pr and pp., the governing equations become ar av;_ OX dV'" r —+ v —= ax ay

o.

a-L'

: ar2

'

dX dY PrdV"2

'

In the pyrolysis region, X $ 1. the boundary conditions, assuming YaXu, = 0. are U- o v'- - ——\

Pr ay

, =/ = 1 at V = 0 16) U = 1,J = 0 as V — = (7)

where the mass transfer number is defined as B^{QYoxJvoxMax -hw \/L iS)

In the extended flame region, X > 1, equation (7) continues to apply, while equation (6) is replaced with

dV

for wall-wake combustion and dU

dY

•= V dY

0 at Y = 0.

0 at y = 0

(9)

(10)

for wake combustion. Temperature and species fields are readily obtained from J(X, Y)

using the flame-sheet approximation, i.e., fuel only exists inside and

oxidizer only outside the flame. At the flame. Y> = yox = 3 = 0. and

Jfe{Xfg, Yt e ) = r/(l + r), which implicitly identifies the flame location. The mass consumption number, r. [4] is defined as the ratio of the relative available oxygen to the stoichiometrically required oxvgen.

r = Yo^vtMf/Yfui/oxMo*. The surface fuel concentration, for X ^ 1, is known a prion

til)

Yfu = [Yf,B - Y0Xm u>fMf/v 0X\iax)}/U + B) (12) The flame height is that downstream location where all of the pyrolyzed fuel is consumed, here approximated as where the reaction sheet

intersects Y = 0. Thus the flame height. Xfe . is implicitlv given by

J,AXf(, 0) = Jfe = r/(l + rl 113) Approximate Solution for Downstream Forced Flow. While

the abrupt change in boundary conditions renders the flow field non-similar near the trailing edge of the fuel slab, it is likely that the combusting system again approaches self-similarity far downstream. An approximate profile of the Shvab-Zeldovich variable. J. in the extended flame zone is now found by coupling the pyrolysis zone

similarity solution with a downstream similarity solution for X » 1. The assumption that the flame extension is large compared to the fuel slab length suggests the similarity variable, n=Y/2X r' n: 114) The stream function, \j. = /(rjlX 1 -. is defined by

= —and V= (15) ay ax

The downstream velocity is then L' = f'(r\)/2. If it is assumed that J/JudX) is only a function of r\, i.e., J/JU.{X) = 0(7?), then

S" + Pr[/0' - -IfHUvXIJu,)] = 0 (16)

is obtained by substituting these definitions into the energy-species equation 15). Primes denote differentiation with respect to the in- dependent variables of firj), tf(rj), and JW [X). To determine if a similarity solution can be found, i.e., if JW 'XIJW is independent of X,

consider the integral form of the energy-species equation downstream

of the fuel slab for an inert, adiabatic wall or symmetric wake: d r~ — 1 puJdw = 0, x > e. dx Jo

(17)

Substituting ti, f and equations i4) and (14) into equation (17) shows

that indeed JW 'XIJU, = -1/2. The downstream energy-species equation is now

H" + Pr(/0' + f'9) = 0 (18)

subject to

tiiQ) = l.tf'(O) = 0,/(0) = 0. The solution is simply

0(t/) = exp j-Pr fJfW dv

where /'(rj) is obtained from the transformed momentum equation

(19)

(20)

Nomenclature

B = mass transfer number. lQY0X „/voxM0X _

h w )/L

cp = specific heat D = species diffusivity D3 = dimensionless heat of combustion, QYox~;voxMoxh a

.

f = similarity stream function Grz = Grashof number. g{Tw — T*)x 3

/

g = acceleration of gravity

h = specific enthalpy, ^ cp dT

J = normalized Shvab-Zeldovich variable. (,J - 3„)/(3w - d.) or 17 - 7.)/('7n, - 7.) L = effective latent heat of pyrolysis

f = fuel slab length Mi = molecular weight of specie 1 Pr = Prandtl number

Q = energy released by combustion of Vf moles of gas phase fuel Rex = Reynolds number, u^x/v*

r = mass consumption number, Y„x „ vfMf/Yfw v0XM0X S = total flux of J in extended flame zone U = dimensionless streamwise velocity u = streamwise velocity V = dimensionless transverse velocity

v = transverse velocity X = dimensionless streamwise coordinate

x = streamwise coordinate V = dimensionless transverse coordinate = transverse coordinate

V, = mass fraction of specie (' 3 = V'.yiy.V// - Y,„/v„x Mte

y = -hlQ - Yox /i' 0XMox

17 = similarity variable

0 = Shvab-Zeldovich variable

X = conductivity M= viscosity

v = kinematic viscosity or stoichiometric

coefficient

5x = mixed convection number. Grr/Re, 2 p = density o = enthalpy ratio. h/h,M

Subscripts

/ = fuel ft = flame ox = oxidizer

t = transferred gas w = fuel surface = = ambient

Superscripts

* = measured from the downstream edge of the fuel slab

232
f" + ff" = 0

with the boundary conditions.

/(0) = 0, /'(«•) = 2

and

f'10) = 0or/"(0> = 0

(21)

1 22)

tor wall-wake or wake combustion, respectively. For wall-wake combustion, the system is identical to the Blasius problem for flow over

a flat plate and although no closed-form expression for firj) exists, numerical solutions are well known [8]. For wake combustion, the

solution for f(t]) is

flv) = 2i». (23)

These results are simply the two asymptotes for X » 1. i.e., flat plate flow for wall-wake combustion and uniform flow for wake combustion.In the pyrolysis region, the energy-species equation in integral form

is — I puJdy = pw uwJw - pD —

dx Jo dv

0 < x < L (24)

JdY = V,MdX at X = 1. (25)

Substituting equations (4) and (6) into equation (24) and integrating along the length of the fuel slab yields

[1 + fi\

1 B I Equation < 17) indicates that S remains constant throughout the ex- tended flame zone; i.e., J is conserved. J is generated along the pyrolyzing surface and is never consumed in the flow field. The extended

flame region is effectively coupled to the pyrolysis region through a

single source of J, with strength S, located at the trailing edge of the

slab.The flame height is obtained by considering the variation of Jw for X > 1 or X* > 0. From equation (25),

JW (X*) = SAX* 1/2 f~ f'ddri Jo

(26)

where X* is the streamwise coordinate measured from the trailing edge of the fuel slab. The flame height is the X* at which Jw = Jft;

i.e. XV = SVUrt C° f'ddiiY-. Jo

(27)

Numerical integration of equations (20, 21) yields J

"

/'tfiwaii-wakeidi? * 1.5 Pr"'16

. while equations (20) and (23) give analytically J"J

/'

t'lwakeic''? = (flVPr) 1 ' 2

: so that

X*/Vlwake|/X*/clwall-wake) = 0.72 Pr~ (23)

i.e.. wake flame heights are ~3/4 (wall-wake flame heights). The B number dependence of S(Pr. B) can be made explicit by

fitting total pyrolysis rate computations,

S = 0.56 Pr"0- 6 B-' 15 (1 + B) (n ( 1 + B), 0.5 $ B « 5.0.5 =S Pr « 2

(29)

Since the generation of J by diffusion decreases with increased blowing, the B dependence of S is weaker than the B dependence of the total pyrolysis rate, as shown by the pre-integral factor in equation

1 25). Substituting equations 1 13) and (29) and the J J f'tidrj fit into equation i27) yields an approximate explicit expression for the wall-wake flame height.

X*/,< wall-wake) * 0.14 ((1 + /-Mil + B" 1 ) B~015 ^n ( 1 + B)} 2 (30)

for 0.5 S B S 5.0, 0.5 S Pr < 2.0 and all r. As examples, equation (30) gives X*/e = 19 and 1.9 respectively for polystyrene tr = 0.14, B = 1.3) and cellulose (r = 0.59, B = 0.8). Equation (30) also fits the numerical X*f£ shown in Fig. 2 within 15 percent for 0.U r « 0.5. The dominant

parameter in equation (30) is r which entered only through Jfe- X*fe

increases strongly as r decreases, since small r implies that much fuel

is available relative to that which is required by stoichiometry and

thus long flames are produced. Additional Results. Numerical solutions were also obtained using the Patankar-Spalding finite difference method iGENMIX) [9, 10] which employs streamwise marching integration. The computations

were initiated near the leading edge of the pyrolyzing slab (X = 0.01) assuming standard, cubic, forced-flow profiles for U and J. Mass

transfer (blowing) effects at the pyrolyzing surface were included. Employing 50 cross-stream grid nodes, the step-by-step procedure

traversed the pyrolysis region and continued into the extended flame

zone. The ratio of the streamwise step size to the current boundarylayer thickness was initialized at 0.01 and gradually increased along

the length of the plate. At the trailing edge of the slab, the step size ratio was reset to 0.01 and again progressively increased downstream. As a check on the numerics, the surface gradients on the pyrolyzing

slab at the trailing edge gave agreement with similarity results [11) within one percent. Detailed profiles and surface fluxes were calculated; flame height results are emphasized here.

Fig. 2 presents flame heights measured from the downstream edge

as functions of B parameterized in r for (a) wall-wake and (b) wake

combustion obtained with equation (27) and S from similarity solutions, an integral approach [4|, and GENMIX. Good agreement be- tween this approximate solution and GENMIX is observed for flame

heights in excess of one slab length. It appears that the simple model

based on conservation of J and large X asymptotic profiles is valid

for synthetic polymer fuels. For short flames, this approximate so- lution overpredicts flame heights, as expected, since large X*<e is an

1.00 MASS TRANSFER NO., 3

1.00 MASS TRANSFER NO., 8

Fig. 2( a ) Oimensionless flame height in a wall-wake measured from trailing Fig. 2( b ) Dimenslonless tlame height in a wake measured from trailing edge edge ol fuel slab versus mass transfer number parameterized in mass con- sumption number for Pr = 0.73

of fuel slab versus mass transfer number parameterized In mass consumption number for Pr = 0.73

106 / VOL. 102, FEBRUARY 1980 Transactions of the ASME

233
essential model assumption: indeed, the accuracy as low as X*ft ~

1 is surprisingly good. The previous approach [4] shows agreement

with the GENMIX results only for short flame heights, X*/e < 1, typical of natural polymer fuels. Many trends agree with those obtained from the previous integral

analysis [4], namely: flame heights increase with increasing B number

and decreasing r number, wall-wake flames are longer than wake

flames, and the dimensionless flame height is independent of Reynolds number. Quantitative differences are obvious, however; the present analysis shows a much weaker dependence of flame height on B number. Briefly, the integral analysis assumed polynominal

profiles for fuel and velocity fields normalized on wall/centerline

values which had to be obtained as functions of X from local elemental

balances. While the approximate polynomials might suffice in the

integral equations, they are not adequate to determine proper wall/

centerline values from differential expressions. Such an approach can

only succeed when the flew is similar. The poor representation of the

detailed profiles in the similar region led to loss of conservation

of the total flux of fuel which became worse the further the flame extended beyond the pyrolysis zone. The excess pyrolyzate results reported [4] for the end of the pyrolysis zone were correct. Here S is held constant throughout the extended flame zone, X* > 0. This emphasis on S, the total flux of the Shvab-Zelovich energy-species

variable J, is responsible for the agreement with the numerical solu- tion and for the difference from the previous approximate integral approach. The constancy of the total flux of the Shvab-Zeldovich variable downstream of the fuel slab demands that a balance be maintained between velocity and J in the extended flame zone. Any decrease in average velocity is thus accompanied by an increase in J; a longer distance is then required for J to decay down to J/e. Thus longer flames result whenever the velocity is retarded, as in the case of the wall-wake. Fig. 2(a), compared with the wake, Fig. 2(6). The ap- proximate solution for wake combustion neglects the velocity defect

that may exist for some distance downstream of the slab. This velocity defect will produce longer flames, therefore the slightly larger GENMIX results in Fig. 2(b) are expected even at large X*/e. The

approximate flame height ratio given by equation (28) is thus a lower bound. The overprediction at short X*/e is primarily caused by

placing the source in the approximate model, S, at the trailing edge

of the fuel slab rather than upstream in the pyrolysis region. A simple procedure for more accurately locating the source is not obvious. Comparisons with Experiment. Flame heights in the wall-wake

of PMMA samples burning in O2//V2 mixtures were measured in a small wind tunnel 12 cm wide by 5 cm high. Slabs of PMMA of lengths

1.3 and 1.6 cm and width 9.0 cm were approximately flush mounted

in the martinitt floor of the test section. Yox . was varied from 30 to 100 percent producing B numbers from 2.0 to 8.0 and r numbers from

0.25 to 0.65 [12]. Data were taken at two free-stream velocities, 85 cm/s and 170 cm/s, determined by corrected volume flow rate measureu S.O (- O 700 x i $ p A Rt,- 1400 5 t- O 1700

!-

AMBIENT OXYGEN MASS FRACTION, YM<

Fig. 3 Comparison of experimental and theoretical dimensionless flame

heights lor PMMA In wall-wake combustion as (unction of ambient oxygen mass traction

ment. Gas and wall temperatures were monitored. Steady-state flame

heights were recorded with an 8 mm movie camera. Fig. 3, which plots the dimensionless flame height. X*fg, versus free stream oxygen mass

fraction, YMm, shows good agreement between theory, equation (30), and experiment. Radiation is probably responsible for the experi- ments slightly exceeding predictions. Though thin, these flames are very luminous. Net radiation to the pyrolyzing surface would, by

decreasing L, increase B. and through the B dependence of Yfw decrease r and thus increase .¥*,<• The data confirm that larger r numbers, produced by higher ambient oxygen concentrations, yield shorter flames and that the dimensionless flame height is independent

of Reynolds number.

Free Flow Combustion

Analyses. The equations which govern free flow combustion near an upright burning surface are identical to the forced flow relations, equation (1), with the obvious modification of a buoyancy term in the momentum equation. du du 0 I du] pu —¥ pv — = hi — + g (p. - p.). ox oy ay \ d\l

(31)

Here the appropriate dimensionless variables are Grf _

p

llP PI

Us

X = -,Y = - JO Dm at e 1 r>zp,\

pV Jo ~ ' (32) Gremv* Gii h'*p m vm V Jo ox

in which Gr, a g{

w - T„)e3 /i>JT„ is the slab Grashof number. The

natural convection momentum equation then becomes

, r oL' , r oU o

2 U

U —+ V —= + - dX dY dY2 (33)

where, assuming uniform mixture specific heat and molecular weight

across the boundary layer, <i> is the enthalpy ratio, h/hw, which in the flame-sheet approximation is

and

ifl = D3 + ( 1 — D3 )J, V'« Y,

<p = (1 + D3 /r)J. Y> Yt(

134)

Equations (34) introduce the single new parameter needed to describe

free flow combustion,

QY.y

(35)

a dimensionless heat of combustion. The transformed continuity and

energy-species equations are identical to equation (5) while the boundary conditions are given by equations (6-10) with the exception

that L'=0asy — «. (36) The strong coupling between velocity and thermal fields in combusting plumes makes it more difficult to formulate simple approxi- mate solutions, however, using the forced flow results, equations (28) and (30) as guides, the following fits, accurate to 10 percent, were

obtained from GENMIX results:

X*/nwall-plumel * 0.24 {(1 + r- | )r-,,16 (l + fl- 1 )fi-|)06 i'n(l + S)D: r"-

0:,

l 4 '' :!

and

X*, 0.9

(37)

(38)

for 0.1 < r < 0.5. 0.5 < B < 5, 2 < D; , < 60. and Pr = 0.73. Results. Numerical computations were performed by GENMIX

using natural convection profiles as initial conditions for the marching

process [13|, the details of which closely parallel the forced flow cal- culations. The combined body force and pressure gradient term, 0, was treated as an apparent pressure gradient in the finite difference

code. The surface gradients at the trailing edge of the pyrolyzing slab

Journal of Heat Transfer 234 FEBRUARY 1980, VOL. 102 / 107
Conclusions

In summary, from the detailed steady, laminar, two-dimensional,

nonradiating, combusting boundary layer analyses of six systems

l wall-wake, wake, wall-plume, plume, mixed-mode wall-wake and mixed-mode wake), emphasizing the constancy of the flux of the Shvab-Zeldovich energy-species variable •/ in the extended flame

region, the following conclusions are drawn:

1 For forced flow, X*fe(r, B. Pr) and is independent of Re?. Explicit expressions are presented which quantify the strong increase

in X*fe as r decreases and the moderate increase in X*ft as B in- creases. The Pr dependence is very weak. Good agreement with ex- periment is obtained.

2 For free flow, X*/e(r, B, Pr, D3) and is independent of Gie- Explicit fits to numerical results are given which quantify the r and B dependence as in forced flow. The dependence on D3 and Pr is weak. Free flow flames are generally shorter than forced flow flpmes for the same fuel and ambience. Reasonable agreement with r—- rriment is obtained. 3 For mixed-mode flow, X*ie

(r, B. Pr, D% $e ) with the forced and

free limits approached at £^ S 10-2 and ^ 5 1 respectively. The

mixed-mode case appears to be a simple superposition of forced and

free flow. 4 Wall-mounted flames are longer than free-standing flames for the same fuel and ambience. This difference depends on flow type and

Pr. i.e.. wall-wake flames are ~30 percent longer than wake flames, wall-plume flames are ~10 percent longer than plume flames. Future effort will be directed at extending these analyses to include

radiation and turbulence. More experimental results for comparison would be valuable. It is hoped that flame height measurement under

controlled conditions will become one of the standard procedures for assessing material fire hazard.

Acknowledgments

Mr. R. Beier obtained the experimental data reported in Fig. 3. The

authors appreciate support from the Products Research Committee

and from the National Bureau of Standards—Fire Research Center. The conclusions are those of the authors and not of the Products Research Committee nor the National Bureau of Standards.

References

1 Emmons. H. W., "The Film Combustion of Liquid Fuel." Zritnthrift fuer Aneewandte Mathematik und Mechanik. Vol. 36. 1956. pp. 60-71.

2 Kosdon. F. -I.. Williams. F. A., and Buman. C, "Combustion of Vertical

Cellulosic Cylinders in Air." Twelfth Symposium {International) on Combustion, The Combustion Institute. 1969, pp. 253-264.

3 Kim. J. S.. de Ris. •(.. and Kroesser. F. W . "Laminar Free-Convective Burning of Fuel Surfaces." Thirteenth Symposium {International) on Combustion. The Combustion Institute, 1971, pp. 949-961.

4 Pagni, P. J., and Shih. T. M.. "Excess Pyrolyzate." Sixteenth Symposium

{International) on Combustion. The Combustion Institute. 1976. pp. 1329-

1342.

5 Ahmad. T., and Faeth. G. M.. " An Investigation of the Laminar Overfire Region Along Upright Surfaces." ASME JOURNAL OF HEAT TRANSFER. Vol.

100. 1978, pp. 112-119.

6 Groff. E. G., and Faeth. G. M.. "Laminar Combustion of Vertical Free- Standing Fuel Surfaces," Combustion and Flame. Vol. 32, 1978. pp. 139-

150.7 Shih, T. M., and Pagni. P. J.. "Laminar Mixed-Mode. Forced and Free, Diffusion Flames," ASME JOURNAL OF HEAT TRANSFER, Vol. 100. 1978. pp. 253-259.

8 Schlichting. H., Roundar\-La\er Theory. 6th ed.. McGraw-Hill. 1968.

p. 193. 9 Patankar. S. V.. and Spalding. D. B., Heat and Mass Transfer in Boundary Layers. Morgan-Grampian. West Wickham. 1967.

10 Spalding. D. B.. "A General Computer Program for Two-Dimensional

Boundary Layer Problems." Report No. HTS/73/48. Department of Mechanical

Engineering, Imperial College of Science and Technology. 1973.

11 Shih, T. M.. "Excess Pyrolyzate from Diffusion Flames." Ph.D. Thesis, Mech. Engr. Dept., University of California, Berkeley, 1977.

12 de Ris, J.. "Fire Radiation —A Review." Seuenteenth Symposium {In- ternational) on Combustion. The Combustion Institute. 1979. pp. 1003-

1016.

13 Sparrow, E. M.. Patankar. S. V.. and Abdel- Wahed. R. M., "Development

of Wall and Free Plumes Above a Heated Vertical Plate." ASME JOURNAL OF Heat Transfer. Vol, 100. 1978. pp. 184-190.

Journal of Heat Transfer

235

FEBRUARY 1980, VOL. 102 / 109
Howard W. Emmons

1

:

The Computer Fire Code

The calculation of the growth of a fire in a building via computer has

!l progressed slowly since the last meeting of this committee. The updated

version, Computer Fire Code IV, has itself been replaced by Computer Fire

Code V. This latest version in Fortran is available on tape, and is accompanied by a "Users' Guide."

The most important aspect of such a code—beyond its ability to calculate

I a fire correctly—is the ease with which it can be used. Thus, Computer Fire

Code V has a completely revised input system. The program is able to handle

a fire in a room of any size containing up to five objects, one of which is

initially ignited. The others will be heated as the fire progresses, and

will ignite at a user-specified ignition temperature (default 740°K)

After they ignite, their gases rise in a plume into the hot layer, and

their fires radiate to each other to provide the expected energy feedback.

The room can have one to five rectangular vents anywhere in the vertical walls.

To supply the required room and object dimensions, and the thermal and

fire properties of the walls and objects in the room, an interactive input

program has been developed. This program asks questions on the console, and

the user supplies the requested information.

The program itself contains a standard room with two objects—one ignited,

the other a target. The first question asked by the computer is: (underlined

items are printed by the computer)

STANDARD GEOMETRIC AND PHYSICAL PARAMETERS (NO - 0. YES = 1)?

On the console there then appears:

236
ROOM NUMBER 1:

0) CHANGE NOTHING (CONTINUE)

1) LENGTH IS NOW: 3.6580E+00

2) WIDTH IS NOW: 2.4384E+00

3) HEIGHT IS NOW: 2.4384E+00

4) NUMBER OF OBJECTS IS NOW: 2

5) PRESENT AMBIENT TEMPERATURE: 3.0000E+02

IF ALL THE ABOVE INPUT IS SATISFACTORY, THEN HIT 0 (FOLLOWED BY<NL} f

IN ORDER TO CHANGE ANY (OR ALL) OF THE ABOVE, TYPE IN THE APPROPRIATE LINE

NUMBERS ABOVE, EACH ON A NEW LINE. END WITH <NL> , <NL>.

Suppose we wanted to study a room 8 x 15 x 10 meters high. The computor

would type:

1.

,2.

3.

<NL> ,<NL>

The dialog would proceed as follows.

1. ROOM LENGTH? 15 <CR> (<CR> is carriage return)

2. ROOM WIDTH? 8 <CR>

3. ROOM HEIGHT? 10 <CR>

The computer then responds by retyping the list of 5 items above with

the new chosen values in their correct place, and asks if you wish to make

any further changes. (No = 0, Yes = 1)

.

Following this, the computer lists, in turn, all of the other adjustable

characteristics of the program with their default values, and asks if you

wish to change them as described above for the room. The adjustable characteristics are:

Room 1 Object 1 (Geometric Properties)

x coordinate, y coordinate, height above floor, thickness, initial

burning radius, object radius, maximum burning radius, input length and

width instead of above radii.

Room 1 Object 1 (Physical Properties)

This object is burning, air fuel ratio, stoichiometric ratio, thermal

i.e. , new line

237
conductivity, specific heat, density, emissivity of surface, fraction

of combustion heat released, heat of combustion, heat of vaporization,

initial fuel mass, ignition temperature, pyrolization temperature,

mass ratio C0

2/fuel, CO/fuel f smoke/fuel, gas flow rate if object is a

gas burner.

These same questions are asked for all remaining objects up to the

number chosen by the computor under "geometric properties."

Vent 1

v/idth, height, transom depth, Side 1 is Room 1, Side 2 is Room 0 (0 is

at present the atmosphere). Each vent desired is similarly covered.

Wall 1

thickness, thermal conductivity, specific heat, density.

Other variables

specific heat of air, flame radiative mean free path, ambient temperature

(outside) , maximum heat transfer coefficient to ceiling, minimum heat

transfer coefficient, heat transfer coefficient to top of horizontal

surface, plume entrainment coefficient, vent flow coefficient.

The results of the calculations are made available in one of two forms.

The user may have any eight physical quantities printed out vs. time in a

nine-column tabular form at user-chosen time intervals (default 10 sec), or

as a block of all thirty seven general variables plus about ten variables

for each object at chosen time intervals (default 10 sec).

The quantities made avilable by the computer are:

Properties of the hot layer

depth, energy, mass, temperature, composition [CO^/ CO, , smoke], rate

of energy increase, rate of mass increase, net rate of heat loss by

radiation, rate of heat loss by convection to ceiling.

238
Pressure at the floor of the room (in meters of ambient air)

For each object

surface temperature, remaining mass, rate of mass loss, feedback radiative heat flux from the layer, heat flux from the walls, radiative heat

loss

For each vent

total mass outflow, total energy outflow, total lower inflow.

For the walls (and ceiling) adjacent to the hot layer (inside the room)

net radiative heat flux from the layer, convective heat flux from the

layer, radiative heat flux from the flames, the surface temperature plus

the same four quantities on the walls outside the room.

The new piecewise linear vent flow calculation mentioned at the last

UJNR meeting in Tokyo has been implemented and incorporated in CFC V. A

fairly simple one-page Fortran code is able to separate and calculate all

seventy vent cases described at that time.

The CFC V still has occasional numerical troubles. In spite of that

fact, three different routines with decreasing time-step are tried automatically and in succession if the fastest method fails to converge to a relative

-4 error of 3 x 10 in thirty iterations.

The Hasimi Diagram for the Computer Fire Code is shown in Fig. 1.

Various results are shown in Figs. 2 through 6. Only a few of the fifty

output variables are shown. The results shown illustrate some of the fire

physics not yet adequately understood. Figure 4 shows the failure to predict

sufficiently high radiation flux. This is believed to be an underestimate

caused by the absence of burning of the fuel in the hot layer. The lack of

knowledge of the products of combustion when flames burn in fire-vitiated

air is the cause of the failure to predict the carbon monoxide concentration

239
by an order of magnitude as shown in Fig. 5.

However, the flexibility of the program in predicting a range of conditions is shown by the predicted effect of lowering the top of the door all

the way from the ceiling to 25 cm from the floor.

Where do we go from here?

Although not sufficiently developed to be included in CFC V, two developments are well advanced.

I. The new piecewise linear solution of flow through a vent is being

used on various multi-room cases. It appears to give results which we believe

to be correct, but which seem to differ somewhat from the results obtained

previously by Tanaka . We hope to clarify the differences during this meeting.

II. Most fire codes have written the physical equations, simplified them

by algebraic manipulation, and then computer-coded the result. This technique results in relatively few (less than a dozen for one room) equations

to be solved. It has, however, a serious disadvantage, since it requires

that the equations must be rederived and recoded each time any change is

made in our knowledge of fire physics.

We have avoided this algebraic manipulation in the Computer Fire Code

so as to maintain greater flexibility, but at the cost of a large number of

equations and unknowns. Mr. John Ramsdell has examined this problem by use

of graph theory. He has developed a method by which the number of essential

independent variables can be reduced to a minimum, and a program by which

the computer can determine the numerical minimum and put the subroutines in

the correct order to use this minimum. We expect this will offer some

improvement in computing time for a single room, and will be extremely important when a one-hundred-room building is being considered.

In separate experimental studies, the detailed composition of a flame

240
at various levels and the burning of a flame in a ceiling layer are being

measured, so as to supply this vital information for incorporation into

the Computer Fire Code.

The Harvard Home Fire Project is supported under a Grant from the National

Bureau of Standards, Washington, D.C.

241

Fig. 2 243
Fig. 3 244
Fig. 4 245
Fig. 5 246
Fig. 6

247
RECENT U. S. PROGRESS IN MATHEMATICAL MODELING

OF FIRE ENCLOSURES

Raymond Friedman

Factory Mutual Research Corporation

Norwood, Massachusetts 02062

September 1980

Abstract ; Current modeling progress at Notre Dame, the University of Dayton

Research Institute, the National Bureau of Standards, and IITRI is described.

The Harvard Computer Fire Code is discussed in a companion paper. In addition,

certain experimental studies useful for testing enclosure fire models which

were done at Notre Dame, at NBS, and at NASA/ JSC are summarized. Some investigations at Factory Mutual of key model elements, especially radiation, turbulent plume structure, and effect of oxygen deficiency, are referenced.

Introduction ; Since the last UJNR Joint Conference in February 1979, development of models to describe fires in compartments has continued in the U. S.

The progress made with the Harvard Computer Fire Code by H. W. Emmons,

H. Mitler, and colleagues is reported in a companion paper. In this paper,

short summaries will be provided of other relevant U. S. work.

I wish to point out that the overall program is being conducted at a relatively

modest level of effort, considering the complexity of the problem, and progress

is relatively slow. However, definite advances are occurring.

University of Notre Dame - The key personnel are J. R. Lloyd, K. T. Yang,

K. Satoh, and N. P. Lynch. They have developed a finite-difference computer

code designated UNDSAFE-II which is based on a field model. There are three

recent publications (1, 2, 3).

248
The calculations were originally limited to two dimensions, but recently (3)

they have extended the model to three dimensions, using 12 x 12 x 12 cells in a finite-difference grid. This model can take into account transients, strong

buoyancy, turbulence, compressibility and smoke diffusion. They currently feel

that adequate quantitative overall flow behavior except immediately above the

heat source may be obtained by using a turbulence viscosity which is 20 times

the laminar viscosity.

In a recent study of ventilation and smoke-layer depth (3), they have assumed a cubic room with a central heat source and a door-like opening of variable size

in one wall. For a doorway of given height but progressively increasing width,

and a given heat source, they find that the steady-state ventilation flow at

first increases proportionally to door width. However, for widths greater than

a critical value, which appears to decrease with increasing door height, the

ventilation decreases to less than half of the maximum value corresponding to

the critical width. Simultaneously the smoke neutral plume rises very

substantially. Figures 1 and 2 show this behavior. The results are compared

with earlier predictions of Thomas et al., (4). A physical explanation of the

phenomenon is provided which is in agreement with the numerical results.

In another computer study, a two-dimensional compartment is analyzed with an opening in the floor and another (offset) opening in the ceiling. The fire is

represented by a constant heat and smoke source. The computational grid was 16

cells high and 48 cells wide. The heat source strength and the locations of the

heat source and the ceiling vent were varied.

The results were presented in a plot of a dimensionless ventilation parameter

vs. a modified Grashof number. The modification of the buoyancy-driven flow by

the f lowresistance of the compartment can be discerned by examining the trends

in the data. The steady-state smoke distributions are also plotted for the 6 cases studied. In two of the cases the long-time behaviors were oscillatory in

nature and the authors say that they can be explained by the developing flow

patterns in the compartment.

249
The other recent study by the Notre Dame group (1) is an experimental program to

obtain data with a growing methane fire in a room adjacent to a corridor.

Temperatures and velocities were measured and flow visualization techniques were

used. The data for the first minute after ignition were found adequate to

characterize conditions when adiabatic walls were assumed. The data were specifically selected to be useful for evolution and development of transient

fire models.

National Bureau of Standards - The center for Fire Research has recently

organized a section of its Fire Safety Engineering Division entitled "Fire

Modeling", under the leadership of J. G. Quintiere. Other members are H. Baum,

M. Harkleroad, D. Corley and K. Steckler. In addition, J. Rockett, Senior

Scientist at the Center, has a major interest in computer models of fire.

Furthermore, their Exploratory Fire Research section, headed by R. Gann, is

concerned with refining the physical knowledge of various processes which must

be considered in an accurate fire model.

Quintiere (5) has recently outlined a framework for modeling vertical wall fire

spread in a room, using a two-layer zone methodology. He discusses the inputs

but apparently has not yet obtained numerical results. He suggests functional

expressions for the dependences of burning rate and of spread on incident

radiant heat flux and local oxygen concentration. He considers the primary

transient process to be the fire growth and spread, and suggests that some fluid-mechanical transients, such as the time to fill the upper room with

combustion products may be ignored. However transient conduction into the wall

should be included. He concludes that the calculating scheme is far from

complete for the wall fire problem, primarily because of uncertainties in fire

growth equations and inconsistencies between actual non-uniformities in wall

temperature near the fire vs. assumed uniform wall temperature in each zone of a zone model.

250
Quintiere and McCaffrey (6) have carried out a series of tests with cribs

burning in a room with an open doorway. The door was either 1/4 open, 1/2 open,

or fully open. The number of cribs in the room was varied from one to four.

Two types of cribs were used: sugar pine and polyurethane foam of nearly the same density. Mass loss, temperatures, velocities, CO2, O2, and CO were measured. The data were correlated; for example it was found that the mass loss

rate varied with the 5/4 power of the number of cribs in the room, suggesting

radiative interactions. The crib burning rates in the room were either smaller

(0.8 times) or larger (1.3 times) than the free burning rates depending on whether the door was 1/4 open or fully open, demonstrating both ventilation

effects and radiant feedback effects. Results were compared with a mathematical

model which ignored transients. The equations (seven non-linear algebraic

equations) were solved numerically; in some ranges complete convergence was not

achieved. When the model output was compared with the data, "the agreement may

be considered fair to good," according to the authors.

In another N.B.S. study related to modeling, K. D. Steckler has accurately

measured flow coefficients for room openings with fire-induced flows, and will

shortly issue a report.

Factory Mutual Research - FMRC has a long-range goal to develop a mathematical

model of a sprinklered fire in a building. As a preliminary step, Alpert and

Mathews (7) have developed a computer program which computes the axisymmetric

flow field induced by entrainment of air into a sprinkler discharge. The model

includes a ceiling and a floor but no walls. Droplet drag and evaporation are included. Calculated profiles of induced air velocity agree reasonably well

with measurements. The work is currently being extended to include the

interaction of a buoyant, upward-moving fire plume with the downward-moving flow

caused by sprinkler entrainment, including cooling of the fire gases.

In other programs, FMRC scientists have been developing quantitative

descriptions of fire properties as inputs for fire models, de Ris (8) has

251
reviewed the state of knowledge of fire radiation. He concludes that, for fires

of moderate scale, the radiation can be adequately approximated by representing

the flame as a homogeneous volume with an effective flame temperature and gray

emission-absorption coefficient. For large-scale fires, he is concerned that

there is significant blockage of radiation by pyrolysis vapors rising from a horizontal combustible surface. There is as yet no way to treat this effect

quantitatively. He provides 42 references.

Work done at Factory Mutual, including that of Markstein (9, 10), Orloff (11),

Santo and Tamanini (12), Modak and Mathews (13) and Grosshandler and Modak (14)

have provided theoretical approaches and experimental data for calculating the

radiant flux emitted by a fire. The experimental work involves measurements of

polymethyl methacrylate , polystyrene, polypropylene, and polyoxymethylene

turbulent pool fires. Consideration is given to flame size and shape,

variations of radiative properties from point to point within a flame, and means

of finding equivalent overall radiative properties for use in a model. In one

of these studies (13) a mathematical model is presented for calculating the

radiation from non-isothermal regions containing variable concentrations of

soot, water vapor, and CO2.

In addition, Santo and Tamanini (12) specifically explored for the first time

the quantitative effect of reduced oxygen on diffusion flame radiation, using

nitrogen dilution. Tewarson et al., (15) measured the effect of reduced or increased oxygen on pool fires of various plastics and methanol, observing

changes of burning rate and combustion efficiency. Perhaps the reader will be

surprised to learn that luminosity always increases with increasing oxygen.

Tamanini (16) has developed a relatively simple one-dimensional integral model

of a turbulent fire plume which assumes top-hat profiles and gives flame-shape

results close to those of more elaborate two-dimensional k-e-g treatments. He

has also (17) developed a model for turbulent wall fires which predicts

structure and burning rate. Heskestad (18) has found a new means of correlating

flame height and structure of buoyancy-controlled turbulent fire plumes.

252
University of Dayton Research Institute - C. D. MacArthur and co-workers for some years have been developing a computer model of a growing fire in an aircraft cabin, called DACFIR. No reports have been issued since the last UJNR

Conference. However interim progress is summarized below.

(1) The concept of the recirculation zone and the zone of uncontaminated air

(see Fig. 3) have been merged into a single idealized region now given the name "recirculation zone". The mathematical formulation of the governing equations

for this region include, in addition to the usual continuity and energy

equations, a momentum equation for the purpose of computing the vertical

component of velocity. The effects of horizontal gas motion, due to entrainraent

by the flames and plume and flow through vents (doors) to the exterior, is

modeled by including artificial mass source or sink terms to the recirculation

zone equations. The size of these terms are determined by the entrainment rate

and the buoyant and/or pressure driven flow through the vents.

(2) A flame and plume model has been developed as an extension of the integral

models of Steward (19) and Fang (20) which admits variable external conditions

and uses a variable entrainment coefficient. To incorporate variable external

conditions, that is, changes in the ambient gas temperature or composition with

height, the equations are integrated numerically rather than in the approximate

analytical manner of Steward and Fang. An expression for the entrainment

coefficient as a function of fuel mass fraction was taken from work by Tamanini

(21) on the k-e-g modeling of turbulent diffusion flames.

The flame and plume model shows some improvement over the earlier integral

methods in predicting the vertical development of temperature and the flame

length but its main usefulness is in its compatibility with the recirculation

zone model, according to MacArthur. Work is still needed to obtain better flame

length predictions and to include flame radiation in a more fundamental fashion.

253
(3) A ceiling jet model has been formulated which is compatible with the

flame/plume and recirculation zone models and takes into account, albeit very

approximately, the effect of the end walls. In this model the horizontal flow

is specified by prescribing its value on a grid of points running along the

cabin length just below the ceiling. Physical constraints determine the

velocities at the outflow of the plume impact region and at the end walls;

between these limits interpolation is used to set the values. The conservation

equations are then used at each grid point to compute the amount of downward

flow into the recirculation zone. Convective losses to the ceiling and walls

are included and radiation from the jet will be added next.

(4) The full-scale cabin mock-up fire test program at NASA/JSC has been

completed and the data are now being analyzed and prepared for comparison to the

updated version of the model, DACFIR.3. NASA will publish a report on just

these tests probably near the end of the year or in early 1981. The report on

the comparison of DACFIR.3 to these tests should be ready at about the same

time.

MacArthur also plans to modify the model further to include the possibility of a spill fire outside the cabin entering through a door or other vent and to add

the capability of compartmenting the cabin.

IITRI . R. Pape and T. Waterman have been developing a computer model of a fire

in a room, called RFIRES, which was described at the last UJNR conference in some detail. The program has not been active since that time. However a computer program documentation and users manual was issued (22). The authors,

with T. Eichler, are now preparing a final report on their modeling of burning

furniture items, with emphasis on a plume model.

254
REFERENCES

1. Lynch, N. P. and Lloyd, J. R. "An Experimental Investigation of the

Transient Build-Up of Fire in a Room-Corridor Geometry". To be published

in Eighteenth Symposium (International) on Combustion, The Combustion

Institute, Pittsburgh, Pa. 1981.

2. Satoh, K., Lloyd, J. R. and Yang, K. T. "Turbulent Buoyant Flow and Smoke

Layers in a 2-D Rectangular Compartment with Vertical Vents". To be

presented at Eastern Section Meeting of Combustion Institute, November 1980

at Princeton University.

3. Satoh, K. , Yang, K. T. and Lloyd, J. R. "Ventilation and Smoke Layer

Thickness Through a Doorway of a Cubic Enclosure with a Central Volumetric

Heat Source". To be presented at Eastern Section Meeting of Combustion

Institute, November 1980 at Princeton University.

4. Thomas, P. H., Heselden, J. M. and Law, M. "Fully Developed Compartment

Fires - Two Kinds of Behavior". Fire Research Tech. Paper No. 18, Fire

Research Station, Borehamwood, England, 1967.

5. Quintiere, J. G. "An Approach to Modeling Wall Fire Spread in a Room", Fire

Safety Journal, to appear in late 1980 or 1981.

6. Quintiere, J. G. and McCaffrey, B. J. "The Burning of Wood and Plastic

Cribs in an Enclosure: Volume I." NBSIR #80-2054, to be released in late

1980.

7. Alpert, R. L. and Mathews, M. K. "Calculation of Large-Scale Flow Fields

Induced by Droplet Sprays". FMRC Tech. Report 0E0J4.BU, December 1979,

presented at ASME Symposium on Polyphase Flow, San Francisco, California,

August 1980.

255
8. de Ris, J. "Fire Radiation - A Review". Seventeenth Symposium

(International) on Combustion, Combustion Institute, Pittsburgh, 1979, pp.

1003-1016.

9. Markstein, G. H. "Radiative Properties of Plastics Fires". Seventeenth

Symposium (International) on Combustion, Combustion Institute, Pittsburgh,

1979, pp. 1053-1062.

10. Markstein, G. H. "Scanning-Radiometer Measurements of the Radiance

Distribution in PMMA Pool Fires". Eighteenth Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, Pa., 1981, in press.

11. Orloff, L. "Simplified Radiation Modeling of Pool Fires", Eighteenth

Symposium (International) on Combustion, The Combustion Institute,

Pittsburgh, Pa., 1981, in press.

12. Santo, G. and Tamanini, F. "Influence of Oxygen Depletion on the Radiative

Properties of PMMA Flames", Eighteenth Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, Pa., 1981, in press.

13. Modak, A. T. and Mathews, M. K. "Nonhomogeneous Pool Fires" Fire Safety

Journal, in press.

14. Grosshandler , W. L. and Modak, A. T. "Radiation from Nonhomogeneous

Combustion Products" Eighteenth Symposium (International) on Combustion,

The Combustion Institute, Pittsburgh, Pa., 1981, in press.

15. Tewarson, A., Lee, J. L., and Pion, R. F. "The Influence of Oxygen

Concentration on Fuel Parmeters for Fire Modeling." Eighteenth Symposium

(International) on Combustion, The Combustion Institute, Pittsburgh, Pa,

1981, in press.

256
16. Tamanini, F. "An Integral Model of Turbulent Fire Plumes," Eighteenth

Symposium (International) on Combustion, The Combustion Institute,

Pittsburgh, Pa. 1981., in press.

17. Tamanini, F. "A Numerical Model for the Prediction of Radiation-Controlled

Turbulent Wall Fires." Seventeenth Symposium (International) on Combustion, Combustion Institute, Pittsburgh, 1979, pp. 1075-1085.

18. Heskestad, G. "Peak Gas Velocities and Flame Heights of Buoyancy - Controlled Turbulent Diffusion Flames". Eighteenth Symposium

(International) on Combustion, The Combustion Institute, Pittsburgh, Pa.,

in press.

19. Steward, F. R. , Prediction of the Height of Turbulent Diffusion Buoyant

Flames." Combustion Science and Technology , Vol. 2, (1970), pp. 203-212.

20. Fang, J. B., "Analysis of the Behavior of a Freely Burning Fire," NBSIR

73-115, Feb. 1973, U. S. National Bureau of Standards, Washington, D.C.

21. Tamanini, F. , "Reaction Rates, Air Entrainment and Radiation in Turbulent

Fire Plumes," Combustion and Flame , Vol. 30, pp. 85-101, (1977).

22. Pape, R. and Waterman, T. E. "Computer Program Documentation and User's

Manual. Development of Fire in a Room, from Ignition to Full Room

Involvement-RFIRES." IITRI Project J6A85, 1980.

257
Figure 1. Ventilation Characteristics.

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( m )

Figure 2. Height of Smoke Neutral Plane.

258
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259
Discussion of Presentations on Modeling

Pagni Presentation

Chaiken: Could you comment on the affects of charring solid,

particularly one with wood which achieves sizable surface temperature

during combustion.

Pagni: I would like to respond with two comments. One primary

effect of char is to reduce the ability of the heat to get to the

virgin material. This has the effect of increasing the latent heat

of the material causing more energy to be provided to produce a gram of fuel into the gas phase. We would expect charring materials

to behave in a more acceptable way than non-charring materials.

However, it makes it difficult for the analyzer of the model. As

the char layer grows these properties become time dependent. I could

only hope that quasisteady approximations would be valid and if the

property at each instant of time is known, I could apply this analyses

to the system. But this is much more information than one needs about

a material whose property doesn't change with time.

Quintiere: We have a potential apparatus that could measure equivalent

properties, such as heat of combustion or heat of vaporization. What

is your opinion as to the viability of such an approach for measuring

equivalent like properties in applying models to evaluate those

materials

Pagni: . . . One has to be careful to have, in the apparatus in which

the property is measured, the condition in which the material will

exist in full scale and that is a major difficulty. There are three

techniques that I think are valuable in getting the laboratory scale

equipment to appear to the material like a full scale fire. Those

techniques are: first, external radiant panels which would simulate

the effect of radiation from other materials to this sample; second,

is the technique of pressuring modeling which was first described by

Prof. Williams theoretically and tested by the group at Factory

Mutual by Dr. Alpert; and the third possibility would be to change the

oxygen concentration in these pressure modeling tests—the difficulty

appears to be that the radiation isn't scaled in the same way as the

production. But the radiation is due to soot and as we change the

oxygen concentration, we might be able to change the soot concentration

in the appropriate way. But this addresses the major long range to the

modeler, which is to provide the transition from small scale tests to

large scale experiments. We could only hope for eventual success.

260
Hasemi Presentation

Pagni: That was quite an amount of material covered in a short

time. Going back to your own work in modeling and flashover, is

there any simple way of distinguishing cases where flashover occurs.

Hasemi: We are still studying. One problem is in calculating the

model for practical purposes since our mathematical model is becoming

more and more complex.

Emmons: This is a comment rather than a question. I was interested

in the solution of Mr. Matsushima which you showed. I believe that

is the same problem that was studied both experimentally and analytically

here at the National Bureau of Standards by the Research Associates from

the Factory Mutual Corporation in 1965 or 1966. Mr. Torrence worked

out the solution to what I think is the same problem. It would be

interesting for Mr. Matsushima to make the comparison.

261
Emmons Presentation

Hasemi: What kind of input information is needed for this model?

Emmons: The program is in Fortran 4 and will operate on a considerable

range of different computers. But each different computer has its own special properties and sometimes our program doesn't run because of some difference between our computer and another one.

Hasemi: Who are the users: firefighters, fire researchers, building

architects?

Emmons: The use is rather limited at present because of the limited

numbers of fires that one can calculate. As an illustration, I am currently using this program in fire soot. The question of importance

is when did the detector detect the fire. By supposing that the

detector is one of the objects, (the detector will not burn, it will

just heat) I can predict the time after the begining of the fire

when the detector responded.

Hasemi: How do you calculate the burning rate? Do you actually

calculate burning rate from heat feedback, or use as specified input?

Emmons: The burning rate was one that was ignited and spread. The

spread rate and the per unit of the area burning rate, pyrolysis rate,

were taken in the following way from an experiment performed in the

open. The measured radius rate and the measured pyrolysis rate were

interpreted as related to the radiant energy input from the open flame.

This means that when the object was burned inside of a room and had

a different radiation rate, it would spread and vaporize differently.

Chaiken: How long does this computation take?

Emmons: The computation takes of the order of the actual fire time,

actually slightly faster than the real fire.

Friedman: Your last slide, does that refer to the second object of

target materials?

Emmons: In examining the effect of the heat of vaporization, I did

not have a target.

Quintiere: Was that for a spreading fire?

Emmons: Yes.

262
Friedman Presentation

Hasemi: Is there any cooperation or coordination among your research

studies?

Friedman: There is a mathematical modeling committee of which Dr. R.

Levine is the Chairman. Perhaps he would care to comment.

Levine: I will give a short report of our last committee meeting.

We used the Hasemi diagram of the interactions in a computer program

on fire in order to try to start a discussion on which algorhythms

should be used for each of these interactions. There were perhaps

fifty people at our meeting and we were not successful. We have

decided for next year, to hold four workshops—each one on a different

phenomenon. In each case we will have a few people selecting the

workshops, almost all of them are people who are doing active research

on that particular phenomenon. In addition, Prof. Emmons, Dr. DeRis

who works with Dr. Friedman, and Dr. Quintiere will be present. We

hope we can arrive at the best algorithm and best input/output

statements for the computer in each case. We will then hold another

large meeting of the overall committees and discuss where we go from

there.

263
DISCUSSION ON MATHEMATICAL MODELING SESSION

General Comments

Friedman: In my presentation earlier, I neglected to mention the work

that Dr. Baum is doing here at the National Bureau of Standards on mathematical modeling.

Baum: I will confine my remarks to advertising a talk that Dr. Rehm

and I will give during the informal session later in the program.

We are calculating field equation models of bouyant flow enclosures

and the transport and coagulation of smoke. We are now in the process

of trying to integrate these two phenomena into a single computer

program.

Emmons: I would like to make a few remarks that I feel are important

with respect for fire modeling.

A number of people have observed questions with respect to

steady burning in the various models. Dr. Quintiere, NBS, Dr. Thomas

of England and Dr. Hasemi have looked at various phases of this

question. These are important mathematical studies of the nature of

the steady burning in enclosures. It appears to me, however, that a very important nonsteady question must still be answered. At any

instant of time the nonsteady development of fire will be developing

towards the steady state. It has been interpreted by the authors that

the discontinuity is evidence of flashover. Flashover is not a welldefined term. There are a number of physical phenomena that at

various times has been called flashover. It is not clear to me that

the new work called flashover is the same as one of those already

defined, or is the new definition. Perhaps more important towards

immediate modeling studies, is the question of whether or not the

occurrence of such discontinuities in equilibrum states have an affect

on the nonsteady development of the fire. Nonsteady development

tending first towards one equilibrium then towards the other, as the

point exists in my program, has never showed itself. I have seen no evidence of such a change. In any complex development of this kind,

the computer program behaves beautifully sometimes and other times for no reason it behaves badly. It is very important to further study

these discontinuities as related to the numerical model, as well as their relationship to possible physics.

264
6. SMOLDERING

265
Modeling of Smoldering Combustion Propagation

T. J. Ohlemiller

Center for Fire Research

National Bureau of Standards

Introduction

This paper is concerned with self-sustaining, heterogeneous oxidation

processes in organic materials. When such a process occurs in a fire

safety context, it is called smoldering combustion. Such processes do occur in other contexts such as underground coal gasification and we

will mention results from that field when they are pertinent.

Nature of smoldering combustion phenomena . Smoldering, like flaming,

is a combustion process which spreads through a fuel when heat released

by oxidation is transferred to adjacent elements of the fuel. The

central role of heterogeneous oxidation (i.e. direct attack of oxygen on

the fuel surface) as the principal heat source in the smoldering of

polymeric materials has only recently been closely examined (1,2); it

appears analogous to, but more complex than, pure carbon oxidation (3)

Since oxygen attack on the fuel surface is paramount, access of the

surface to this attack plays a major role. It will be seen, furthermore,

that the relative directions of movement of oxygen and reaction zone can have a major impact on the smoldering process.

Dominance of heterogeneous oxidation does not preclude some heat

release via gas phase oxidation. However, this dominance does generally

lead to a combustion process considerably different in quantitative

terms from the more familiar gas phase dominated flaming process. While

spread of smoldering and flaming both occur through coupled heat release

and heat transfer mechanisms, smoldering typically yields less c'omplete

oxidation of the fuel, lower temperatures and much slower propagation

rates. All of these smolder characteristics can vary widely with oxygen

supply. Stable smoldering is possible in some circumstances at equivalence

ratios only a few percent of stoichiometric. At the opposite extreme, a strong oxygen supply can raise the intensity and temperature of smolder

to such a degree that gas phase reactions become dominant and flaming

propagation takes over.

266
Fire safety hazards involving smoldering . Only rather recently has

smoldering been recognized as a major fire safety hazard in the United

States. Clarke and Ottoson (4) found cigarette ignition of bedding and

upholstery materials to be the single largest cause of residential fire

deaths. The cigarette, itself a smoldering cellulosic fuel, is nearly

ideal as a smolder initiator in susceptible fabric and filling materials.

In such materials, a self-sustaining smolder process can often be established

well before the cigarette is consumed. This particular problem is

coupled to both fabric and filling response to heating. Once established

in this manner, smoldering becomes a steadily growing generator of

carbon monoxide and other toxic gases as the size of the reacting region

enlarges. This smoldering process may spread stably for an hour or so then abruptly transition to flaming combustion. The hazard is thus twofold—toxic gases during smoldering and rapid destruction following

flaming transition. Which of these is most responsible for the observed

death toll is unclear; both undoubtedly contribute.

The increasing interest in residential energy conservation has

resulted in a strong demand for effective insulating materials, particularly

for attics where heat losses are greatest. Cellulosic loose-fill insulation

is quite effective and comparatively inexpensive. It is essentially

ground wood, being made mainly from recycled newsprint, reground to a fibrous, fluffy form that is blown into place. The oxidation chemistry

of wood clearly renders this material combustible. A variety of additives,

typically in fine powder form, are included in an effort to control this

combustibility. They are rather effective in suppressing flaming but are much less so for smoldering. When the insulation is improperly

installed, heat sources such as recessed light fixtures can cause smolder

initiation. Once started, this smolder becomes self-sustaining, spreading

through an attic space and posing the same toxicity and flaming-potential

hazards as in the above case.

The two problem areas above, upholstery/bedding and cellulosic

insulation smoldering, probably comprise the two most widespread and common hazards from this form of combustion in the United States today.

They are also the most extensively studied in some respects. There are numerous other problems, however. For example, wood and certain other

267
low permeability building materials (particleboard sheathing and some types of rigid foam insulation) can be induced to smolder in configurations where surface heat losses are suppressed. Spontaneous heating and

ignition, usually to smoldering combustion, have long been a problem with

a variety of natural products, usually cellulosic in nature. In industries

which process oxidizable materials in finely divided form there is

danger not only from dust explosions (a flaming problem) but also from

smoldering ignition of dust layers accumulating within or on top of hot

processing equipment. These industrial problems have been extensively

reviewed in a book by K. N. Palmer (46) and will not be examined here in

any depth.

Some experimental characteristics of smolder propagation . Table I is a brief summary of the smolder behavior observed for a variety of

fuels in several configurations. The list of results is by no means complete but it gives a representative picture for smolder in organic

materials. The study by Palmer (5) presents the most complete parametric

examination of smolder behavior for configurations that are rather

complex but realistic. The study by Lucca (12) is the first systematic

comparison of configurations simple enough to be modeled in detail.

(The forward/reverse terminology is explained below.)

Cellulosic materials show up most frequently in Table I because

they are so common and nearly all of them smolder. (It is interesting

to note that pure cellulose does not smolder, at least in small masses;

it requires alkali metal contamination to sustain smolder (6,7).) There

are, of course, numerous other materials with the potential to smolder

but both the material and the way it is used must be favorable to

smoldering in order for it to emerge as a fire safety hazard.

The various results in Table I generally justify the description of

smoldering as a slow, low temperature combustion phenomenon that responds

with increased vigor when the oxygen supply is enchanced. The slowness

268
is apparent in the magnitude of the smolder velocities. It is interesting

to note that these do not vary greatly (except for a cigarette during a draw) in spite of wide variations in fuel type and configuration. This

probably reflects the oxygen-supply-limited character of the process; a kinetically-limited process would be expected to vary more with various

materials. The low temperatures generally reflect the fact that smoldering

causes quite incomplete oxidation of the carbon and hydrogen in the

fuel. Part of this incompleteness is probably a consequence of the

detailed nature of the surface reactions but part is also a result of

how various configurations minimize or preclude gas phase oxidation of

surface-derived molecules (pyrolytic or oxidative) . One feature of

smoldering that is not evident in Table I is the variability of the air

to fuel-consumed ratio as air supply is changed. Smoldering, at least

in some configurations, achieves an extra degree of tenacity because it can adapt to very weak air supplies by varying its effective equivalence

ratio (11).

General factors favoring smoldering combustion . All of the fire

safety problem areas noted previously do not have a unique set of common

factors but certain chemical and physical factors can be discerned to be

conducive to smoldering. First, access of the fuel surface to oxygen

attack clearly enhances heat generation by heterogeneous reactions. The

low diffusivity of oxygen in liquid or solid fuels effectively limits

oxidation reactions to the interfacial region between fuel and gas

phase. The reaction rate of unit volume of fuel can be increased many

orders of magnitude if that fuel is permeated with pores or is in a finely divided form. Second, this access of oxygen to the surface must

be retained as the fuel increases in temperature due to self-heating or external heating. The reaction will be effectively suppressed if the

fuel melts or forms a liquid product whose surface tension causes contraction and loss of the extended interfacial area. Formation of a solid product or the presence of an extended area support material thus can favor smoldering; this preserves reactable surface and/or provides

an insulation for the reaction zone.

269
Third, the fuel clearly must be amenable to exothermic attack by

oxygen but the rate of that attack can vary widely. What counts is the

reaction rate under the thermophysical conditions at which the material

is used. Smolder initiation depends on a competition between heat

generation rate and heat loss rate. This also implicates a fourth

factor—conditions which retard heat losses from the reaction zone thereby lessening the requisite reaction rate for smoldering. In the case of smolder initiation, at least, heat losses can be influenced not

only by the conductivity and thickness of the fuel but also by the

initiating heat source. If that source is sustained in duration for a time sufficient to thoroughly pre-heat all adjacent fuel, the losses

from the reaction zone are further diminished. Sustained sources of

intensity insufficient to cause fuel ablation or flaming are thus conducive

to smoldering.

Note that char formation per se was not listed as a prerequisite

factor in smoldering. A char is an ill-defined material and one has to be cautious about the meaning of the word. The blackened solid product

formed by heating many organic materials is rarely pure carbon; its

chemical make-up and its physical properties are usually dependent on

the total history of its formation. It is deceptive to say that "char"

is the true fuel for smoldering combustion. The tendency to form a solid product (by oxidative or inert pyrolysis) frequently means the

extended surface area of the condensed phase is preserved or even enlarged;

as noted above, this is a smolder enhancing factor. If there is a persistent solid organic phase, there can be a continuum of exothermic

surface reactions available to drive smolder and some of these may start

while the fuel is only slightly discolored. While the term "char" is

useful (and is used here) , one should be careful about what it is meant

to imply.

There is, of course, an interplay among these factors that ultimately

determines the smolder hazards of a particular usage of a particular

material. Note that the hazard of a material is very much dependent on the context of usage. Some situations bring together a particularly

undesirable set of factors. In the upholstery smolder problem, two

smolder-susceptible materials (cellulosic fabric and polyurethane foam

or cotton batting) are juxtaposed and then exposed to an already smoldering

source (a cigarette). In cellulosic loose-fill insulation, a thick,

heat-preserving layer of a high surface area wood product sits atop a

270
a prolonged heat source like a recessed light fixture. The great potential

for trouble in such circumstances should be more widely recognized.

This recognition would come more easily if the smolder hazard could be more readily quantified. Unfortunately this quantification depends on

the specifics of all the above factors and only very limited studies

have as yet been made.

In the present overview of modeling efforts, we will first examine

a general classification scheme for smolder propagation problems.

Following this, we will survey the modeling efforts currently in the

literature and try to decide where further work is most needed.

Smolder Configurations

Conditions favorable to smolder may be encountered in a wide variety

of fuel configurations; the resulting propagation process will vary

quantitatively and, to a lesser extent, qualitatively with such configurations

(so also will the likelihood of smolder initiation). By configuration

we mean here the macroscopic and microscopic details of fuel geometry

and air supply that dictate how oxygen and fuel come together to react.

Characteristic Lengths . In examining the question of smolder configuration,

it is useful to keep several characteristic lengths in mind. There are,

first of all, certain physical dimensions that are relevant:

il^p - characteristic dimension of fuel particle

£„_ - characteristic dimension of effective fuel element

Note that in most problems £_„ equals either I or I . There are also

certain lengths characterizing the smolder process or component parts of

it:

£ OTT - characteristic thickness of propagating smolder wave

FE

'FB characteristic dimension of array or bed of fuel elements

I.REAC

- reaction zone length - t.REAC

- convective heat transfer length
Also for each of the three physical scales above (particle, element,

array), we have characteristic diffusion and conduction lengths since

each scale carries a different diffusivity:

1/2

£„ - conduction length - (K t,_ TT ) c SW

1/2

J> - diffusion length = (D t OI7) D SW

In the above diffusion lengths, t is the smolder wave passage time

oW

(t = £ • V ); V is the smolder propagation velocity; K and D are thermal and molecular dif fusivities, respectively. Also t is a characteristic reaction time (reciprocal of characteristic reaction rate)

The thermophysical smolder configuration depends on relative values

of these various characteristic lengths. Since there are several lengths,

the number of permutations is obviously large and we shall not attempt to

consider all possibilities here. However, some useful distinctions can be

made; some of these are summarized in Figure 1.

The first pertinent length we consider, that of the effective fuel

element £ is roughly defined as the largest fuel aggregate not permeable

r li to airflow under the conditions of the problem in which it appears. This

permeability question is quantified further below. Note that, in virtually

every smolder problem in the fire safety field, there will be a flow of

air whether forced or buoyantly induced. We are concerned with what scale

of fuel mass this flow penetrates (if at all) since this bears on the

complexity of the problem.

With the above definition, the value of £ for the same array of fuel

FE can change with the factors that dictate the airflow through or around the

array. For example, a bed of loose-fill insulation is made up of wood

fibers. When such a bed is smoldering under the influence of a forced

flow of air that passes through the bed of fibers, £ equals the effective

fiber diameter £„_. However, when only buoyancy is present, it is insufFr

ficient, as will be shown below, to provide the dominant oxygen supply.

Rather, it is diffusion from the exterior of the bed that supplies most

oxygen; the smolder wave then behaves as if £ is the characteristic fuel

272
bed dimension £ (e.g., its thickness). As another example, a cigarette

alternates between these two cases: when it is being consumed by buoyant

convection, i equals the cigarette diameter (£ ); when the smoker

FE FB

draws on the cigarette, I equals the tobacco particle size £ in the

FE FP

forced flow smolder region. For single pieces of low permeability materials such as wood or closed cell polymeric foams there is no ambiguity;

£ is equal to the characteristic macroscopic dimension of the piece

(£ „ = ) . If, on the other hand, the problem involves an array of

r E r r such pieces, one must examine the flow permeation through the array just

as in the insulation case mentioned above.

To these physical dimensions we want to compare the characteristic

lengths associated with internal aspects of the smolder process. The

overall thickness of the propagating smolder wave £ typically is

roughly equal to the sum of the reaction zone thickness ^j^q and a pre-reaction zone dominated by transport processes (of length £ or Hi

£ for conductive or diffusive dominance in an array or bed of fuel

elements; if convective heat transfer dominates, the pre-reaction length

is of order £„„_. „; for mixed convection and conduction, this length is

CONV ,

B

of order ^g/^j^M^ w^ere ^ntm ^ S ^e net thermal mass flux in the two

phases; if radiative transfer dominates, as in very porous materials, it

is of order 1/a , the radiative path length).

B

Smolder wave many elements thick . If the smolder wave thickness

£ is large compared to the effective fuel element size £„„, we have

one major subdivision of smolder problems as shown in Figure 1. We

implicitly assume in this subdivision that there is a large fuel array

of size £ >> £ and £ >> £ CTT . This subdivision encompasses such

FB r E r B o W problems as forced flow smolder through loose-fill insulation, a cigarette

during a draw and at least some problems of coal or oil shale gasification

where the starting material is finely particulated

.

In this first subdivision, many fuel elements are encompassed by

the smolder wave and we have the possibility of a macroscopically one- dimensional (1-D) propagation process. That is, gradients of temperature

and species on the scale of £ may only be significant in the direction

of smolder wave propagation. This is not likely to occur in practice

273
without some intentional efforts but it is a welcome simplification useful

in qualitatively simulating the smolder problems just mentioned.

Tractable detailed models of such smolder propagation require a further simplication as well, that of microscopic one-dimensionality.

This requires

( W" 1; ( W~ 1 (1)

These conditions imply that there are no gradients of temperature or species within each effective fuel element. The second of these two con- ditions is usually the hardest to satisfy because of low species mobility

in micropores of the fuel element, especially if £ = I and the fuel

r ii r r element is a low porosity solid like coal or a char. If the conditions

in Equation (1) are satisfied, the smolder propagation process can be

simulated by a fully 1-D model that only considers gradients on the scale

of £ OTT . The simulation will only be qualitative, of course, if the real

smolder problem of interest is 2-D on the scale of £ CTT . If the conditions

in Equation (1) are not satisfied, modeling is still possible but it

becomes much more expensive; this problem is being confronted in the

underground coal gasification field.

Simpler limiting cases . As noted in the upper part of Figure 1,

there are two limiting cases that are macroscopically (and possibly microscopically) 1-D, depending on the relative directions of air and smolder wave movement. Forward smolder is the term applied to the case where

both air and smolder zone move in the same direction. (This is also called

counter-current smolder; an observer moving with the reaction zone sees fuel and air enter it from opposite sides.) Reverse smolder (co-current

smolder) applies when the smolder zone moves toward the incoming air.

These distinctions are important because they can have considerable effect on the character of the smolder process. Forward smolder tends to move

more slowly and to completely consume the fuel. The fuel heat up zone ahead of the wave is devoid of oxygen; this can strongly affect the amount

of char formed as well as affecting the composition of the smoke. Reverse

smolder is faster for the same air flow and less complete (to a varying

degree), proceeding at a rate greatly dependent on heat transfer (like a

274
deflagration wave) . The fuel heat up zone is highly oxygenated since the wave moves toward the air flow.

In general, real problems are neither purely forward nor purely reverse smolder in character since the air supply and the reaction zone are not usually constrained to be collinear. The above limiting cases are of interest both because some of their character can be seen in more

complex problems and because they are more tractable than the arbitrary

cases; we thus can obtain information pertinent to the most general three

dimensional cases indicated in Fig. 1 by examining the simpler limiting

cases

.

Smolder wave comparable to fuel element . If the smolder wave

thickness I is less than or comparable to the effective fuel element

o W the propagation is multi-dimensional in character on the scale of

rt

We then have the second major subdivision of smolder problems as shown in the lower half of Fig. 1. (There is, in principle, a 1-D limit

to configurations, such as that suggested in Fig. 1, when S, >> I and

I >> I but this does not appear to be pertinent to any real smolder

Chi Ft, problem.) The smolder wave tends to spread over the outer surface of the

fuel element and penetrate inward by consumption of the outer layers. If

there is only one such fuel element involved, this confinement of reactions

to the outer surface will inhibit smolder because of heat losses. Survival

of smolder in these circumstances requires either very favorable chemistry

or inhibition of the heat loss by an ash, for example. Many cellulosic

materials seem to have both of these survival factors.

There is, of course, a classic heterogeneous oxidation problem that

falls in this category, that of the consumption of a single char particle

in a furnace environment. This problem area is extensively reviewed in

ref. 20; many of the thermophysical phenomena discussed there are pertinent

here as well.

If the heat losses from a single fuel element preclude its smolder

when it is isolated, the inclusion of another (or many more) fuel element (s)

may change this. The sketch in the lower half of Figure 1 suggests two

slab-like fuel elements forming an air gap (this could be a wall cavity)

;

275
heat losses from the inner surface of each are mutually cancelling.

Effects such as this enhance the smolderability of charcoal briquets or logs in a fireplace.

Once again, in the lower half of Figure 1, there exist two limiting

cases in the relative direction of movement of air and the smolder wave. The qualitative differences between these limiting cases should be

essentially the same as in the previously discussed case.

Assessing fuel permeability . Recall that we have defined the

effective fuel element as the largest fuel aggregate not permeable to

airflow. It is pertinent then to attempt to assess what conditions permit

airflow permeation through a fuel aggregate. We compare convective air

flow-through to diffusive supply from the exterior of the fuel mass

under consideration to discern when that convective supply can be dominant.

Consider a flat layer of smolderable fuel of thickness I and width

much greater than £. Assume the convective flow through the fuel is

supplied by buoyancy generated in the smolder wave and that this buoyancy

is balanced by the drag the flow experiences in passing through the

permeable fuel mass. Then we have

The symbols are defined in the Nomenclature Table. The term on the left

in Eqn. (2) is the laminar drag, proportional to gas viscosity and flow

velocity; the term on the right is the buoyancy force measured in the

peak temperature zone of the smolder wave. The proportionality constant

a^ is a measure of the fuel permeability to gas flow. This equation can

be solved for the gas velocity and from this we get an approximate measure of the convective oxygen flux

"oC

=

PM

Y

OXA

V

G

(3)

This ignores the increased gas mass flux due to fuel gasification. For

this convective flux to dominate over diffusive oxygen supply, at least

276
when the reaction zone is a mid-depth in the fuel mass, we require that

it be, say, ten time larger than the diffusive flux at that point. The

diffusive flux at mid-depth may come from both bounding surfaces of the

where we have assumed that Y goes to zero in the reaction zone. This

ux expression ignores the effect of convective counter-flow on the diffusive

flux from one bounding surface. Both Eqn. (3) and Eqn. (4) tend to

overestimate their respective fluxes.

From the requirement that rh be at least 10 m , we can solve for

\J\j vJD the upper limit on the gas permeability constant that satisfies our criterion for dominance of convective oxygen supply.

This is an approximate guideline for the range of fuel mass permeabilities

that will permit dominant convective supply to the fuel mass interior. If

fuel mass in question satisfies Eqn. (5), we look at the next lower scale of

fuel mass to discern if it dictates as defined above since the scale

FE

just examined does not. For highly porous fuels such as flexible polyurethane

3 cushioning materials, a^ can vary widely from about 1.0 to 100 g/cm sec (13);

for a typical cellulosic, loose-fill insulation, a is approximately

3 10 g/cm sec. For typical smolder conditions, Eqn. (5) reduces to a -2

<_ 10 I; since £ for these fuels is 10-30 cm, typically, they will not

meet the criterion for high permeability. An exception might be cellulosic

insulation in a vertical wall cavity where £ could be much greater.

This conclusion only holds when natural convection provides the

oxygen supply. Forced convection may be pertinent to realistic smolder

hazard problems. For example external winds penetrating vent holes or internal home ventilation could result in forced air flow through loosefill insulation. Then the right side of Eqn. (2) is replaced by the

pressure gradient AP/£ and Eqn. (5) is replaced by a calculation of the

minimum imposed pressure force for convective dominance. Thus a given

fuel mass scale may dictate the effective fuel element size I in one

fuel

(4)

(5)

277
set of conditions but in another, £ may be less (i.e. I = I or £ rE FE FB FE

= V•

Other considerations . It is worth noting that the varying configurations

in Fig. 1 will affect not only smolder propagation but also the ease with which smolder can transition into flaming combustion. For example,

smolder within a porous fuel mass is not likely to transition unless

there are large air gaps (presumably larger than a flame quench distance)

The available data on the transition process are meager (5,17,27,28).

The distinctions in Fig. 1 are not as important for smolder initiation,

however. Since a moving front does not yet exist during ignition, the

forward and reverse distinction does not apply. Fuel permeability is

pertinent primarily because it affects the extent of oxygen depletion

during ignition. Smolder initiation in high permeability fuels can be

treated as a problem in thermal ignition theory (14,15,16); smolder

initiation in low permeability fuels has received only limited study

(17).

It appears that virtually every established smolder process quickly

becomes oxygen-limited (i.e. oxygen concentration goes to zero in the

reaction zone) . If so we can make the following qualitative inferences

about smolder spread. Once smoldering is fully initiated on some part

of the outer boundary of a fuel, it will undergo a transient spreading

process and the smolder wave may arrive at a steady or quasi-steady

shape that then consumes the remaining fuel. (Since this evolution

takes time, the steady state may never be reached with small fuel masses.)

The transient evolution of the smolder wave is due to heat transfer but

278
the rate at which heat is evolved and made available for transfer is

dictated by the rate of oxygen supply. Thus the relative rate of smolder

penetration into the bulk of the fuel versus spread over the outer

surface is dependent on the fuel permeability considerations discussed

above. The one factor that can always override this oxygen-limited

spread process is heat loss. If heat losses from some region of the

spreading front become excessive, the local temperature will be suppressed

to the point where the kinetics of oxidation, rather than the rate of

oxygen supply, limit the heat evolution rate. This will slow or stop

spread into that region. A steady-state is finally achieved when (and

if) a stable balance of heat generation rate versus heat transfer rate

is achieved at each element of the smolder wave. The shape of the steady

state wave will be largely determined by oxygen transport processes to the

reaction zone.

Smolder Chemistry

During the passage of a smolder wave, the fuel, which typically

consists of a complex polymer or mix of polymers, is degraded and gasified

by both heat and oxygen. Even when the fuel is a single polymer, this

degradation/gasification process will involve large numbers of series

and parallel reaction paths. Some of these will be endothermic, others

exothermic. About all that can be stated for certain about this overall

process is that it must have a net exothermicity , otherwise self-sustaining

smolder could not occur. In broad overall terms, most polymeric fuels

can be at least approximately described by a degradation/gasification

scheme like the following.

scheme is the composite result of numerous reactions of unspecified

279
nature. For example, for cellulose, the pyrolytic pathway (^) has been

under investigation for years but it is not fully clarified. Again for

cellulose, the initial oxidative reaction paths have examined to some extent (18) and the char oxidation is also just beginning to be investigated

(1,2). For other smolderable fuels the underlying chemistry is even less

clear. What is termed "char" in the above scheme has to be operationally

defined since it has no definite composition (and probably differs

whether formed in the presence or absence of oxygen)

Much of what happens to the polymeric fuel during smolder is qualitatively

analogous to the fate of coal during devolatilization and oxidative

gasification. There is an extensive literature in the coal field

(19,20,21) which can provide insights into the smolder problem, especially

physical processes bearing on the above degradation scheme, but the

results cannot be directly applied here.

Even though the above type of scheme is only a crude representation

of reality, it can be quite useful if it can be quantified properly. A

tractable smolder model could handle four overall reactions; from the

model one can then learn what factors affect which of these overall

stages. This can in turn help pinpoint what aspects of the underlying

chemistry might best be further examined in efforts to retard or suppress

smolder

Since each step in the above scheme is a composite of several

reactions having, in general, different activation energies, quantification

of the scheme should ideally be done in the same conditions of atmosphere

and heating rate as occur in smolder. Otherwise, the apparent kinetics

of any given composite reaction step can change. In practice this can only be approached at present, especially because heating rates in

smolder (1/2 °C/sec and up) frequently exceed present instrumental

capabilities. Thermal analysis (thermogravimetry and differential

scanning calorimetry) are the best techniques presently available for

quantifying the overall rate laws for each step in the above scheme.

Typically this requires sample runs at two or more heating rates and

several oxygen levels (21% to 0%) . Techniques are available for fitting

rate equations to the data (22,23).

280
A further important consideration pertains to matching the above

scheme to actual overall smolder chemistry. Physical factors affect the

degradation process as well as chemical factors. Oxidation occurs on the available surface of the fuel, pyrolysis in the bulk of the fuel.

The available surface of the fuel may involve micropores either initially

or after some extent of reaction. The oxidative/pyrolytic competition

depends on the surface to volume ratio, among other factors, and that

ratio may change as degradation/gasif ication progresses. The physical

form of the sample should be the same as that occurring in real smolder

so that the physical interactions with the chemistry are the same. One

should recognize that the "kinetic rate law" derived for any overall

reaction step may be describing physical as well as chemical changes;

thus it is dangerous to assign any mechanistic significance to the

apparent activation energy.

Smolder chemistry is in a rather primitive state; there is much to

be learned that could have a large impact on the smolder hazard problem.

Until the situation improves, schemes such as that above can be applied

to carefully limited sets of conditions.

Smolder Propagation Models

The number of smolder models in the literature is rather small,

reflecting the underdeveloped state of this field. They can conveniently

be broken into two categories which will be called simple and complex.

The simple models typically are applied to rather complex configurations

where a detailed description quickly becomes intractable from the solution

standpoint. The main value of the simple models is in providing a qualitative prediction of the effect of pertinent parameters on smolder

propagation characteristics. Potentially they can draw together a set

of experimental measurements, rationalize their main features and provide

an approximate extrapolation of behavior to other sets of conditions.

The more complex models begin, at least, with simple configurations,

impose fewer assumptions about controlling factors, and let the model

solution tell the story of what factors(s), in what conditions, govern(s)

the output of interest. The complex model is, in effect, another experimental

tool for examining the parameters that influence smolder characteristics;

it is a tool more easily manipulated and probed than the laboratory

smolder system. Of course, no model is better than the physics and

chemistry that go into it.
1. Simple Models

Cohen and Luft (Ref. 8) . This is a phenomenological model of lateral

smolder spread through a thin bed of fuel particles; oxygen supply is by

natural convection. This is a 1-D model of a 2-D propagation process.

Here £ - I and both are comparable to the fuel layer thickness; the

problem falls in the general category of the lower half of Fig. 1 since

the smolder wave may be mixed forward/reverse in character. The model

begins with the 1-D approximation that convective and conductive heat

fluxes from and to the virgin material where the smolder wave is moving

are in balance.

is the thermal capacitance ratio of air to solid entering the reaction

zone. There are four unknowns here, Tw , I , m , m, . Further approximate M s s A

relations are introduced specifying peak temperature, air velocity and

fractional conversion of the solid. These are all utilized, together

with some of the experimental smolder measurements, in a manner not

sufficiently explained; some of the intermediate steps and results are subject to question. The peak temperature is thermodynamically determined

on the assumed basis of CO formation only (not examined experimentally)

Air supply is taken to be dictated by a drag/buoyancy balance in the

particulate fuel bed; oxygen diffusion, which can be shown to be of the same magnitude, is ignored. The authors calculate fractional conversions

of the solid which are implausibly low (2% in some cases) . They seem constrained by an attempt to justify measured temperatures which themselves are implausibly low (see Table I, for example). The general approach

has merit as a basis for correlating experimental trends on thin fuel

layers but would benefit from a few additions as noted. Comparison with

the more extensive experimental data of Palmer (5) would be beneficial.

Kinbara, Endo and Sega (Ref. 9) This is a 1-D model of 2-D downward

smolder propagation in single, low permeability fuel cylinders. Air

282

s

where
flow is due to natural convection. Again £ - H and the problem

falls in the lower subdivision of Fig. 1. (Also £ _ = JL_ = cylinder

FE FP

diameter.) Downward propagation against upward buoyant air flow around

the cylinder gives the problem a 2-D reverse smolder character. The

model is based on the 1-D heat conduction equation for the solid fuel;

estimates are made of heat production and heat loss terms in this equation.

The development seems somewhat forced in an attempt to match experimental

trends for the effect of ambient temperature and fuel cylinder radius.

Heat production rate on the fuel surface is taken to be oxygen-supply

limited; the rate of supply is assumed proportional to the temperature

difference between the surface and ambient (assumes mass and heat transfer

numbers are equal) . The heat production rate is also proportional to

the reacting surface area but here the actual conical shape is ignored

and a "correction" for effective surface area is applied. Finally, heat

production rate is assumed inversely proportional to the difference

between ambient temperature and a measured instantaneous ignition temperature.

Heat loss from the surface is Newtonian; the effective heat transfer

coefficient and the surface area "correction" are obtained from separate

experiments. The resulting steady-state energy conservation equation is

the following.

\J-~ + iUcJr +2(7 + r 2) ( T.-T - h) (t-T ) = 0

Fdx2 F Fdx \c c/\io / \ 0/

This equation has solutions of exponential form that involve a parameter

grouping called 8. The authors offer a rather obscure argument that

6=0; this leads directly to

..•-(as) (*.*yw*>-i)

This is the same form as that in which their experimental data on the

effects of r and T. are correlated. The unknowns q and A are inferred

c 1

n from this match and appear plausible. The same development is applied

to rectangular cross-section materials and leads to a very similar

expression which again correlates their experimental data. Here there

is some apparent conflict with the data of Palmer (5) on fiberboard

2 strips; he found a linear relation (rather than V

g

) between smolder

velocity and sample dimensions (perimeter/area). The range in dimensions

for both studies is too narrow to settle this definitively.

283
Sega (24,25) has extended both the experimental and theoretical

work on downward smolder propagation in low permeability fuels to other

geometries including a hollow cylinder. The results are correlated

similarly. The model is developed in a somewhat different fashion that

accounts for the non 1-D geometry of the reacting surface. The final

correlating equations for smolder velocity in terms of sample dimensions

and temperature are similar to that above. This work has not been

translated to English so detailed comments cannot be made at present.

Williams (Ref. 26) . This development is couched in very broad terms in

the midst of a general discussion of fire spread mechanisms; it is

intended only as a phenomenological description of smolder spread

mechanisms. The author notes that oxygen-limited smolder is more probable

because kinetically-limited propagation is often unstable. This leads

to the interesting rough criterion for a smolder extinction limit:

Y

n

A exp (E/RT ) < p D /l ox c M ox ox G

This says that extinction can be expected when the kinetic oxidation

rate of the fuel drops below the diffusive oxygen supply rate (£ is a characteristic length for oxygen diffusion) . Applying this in practice,

of course, calls for more detailed analysis of a specific configuration.

For a permeable fuel in a forward smolder mode (eg, a cigarette

smoldering upward with a buoyant/diffusive 0^ supply), Williams equates an oxygen-limited heat generation rate to the fuel heat-up enthalpy to

get a rough expression for smolder velocity:

V = Q p D /£ p C (T —T ) s xox ox ox G F F M o

If the fuel is not permeable, the reaction is confined to the surface

and a configuration-dependent heat loss must be subtracted from the heat

generation rate. (In fact, heat losses must also be included in the

permeable forward smolder case, otherwise regenerative reactant heating

precludes the assumed steady state.) If £ is assumed proportional to a G

lateral dimension of the fuel, the resulting expression will look roughly

like that of Kinbara, et al, above but it is linear in V , not quadratic.

The expected dependencies here are qualitative only since no realistic

conf igurational details are included.

284
Moussa, Toong and Garris (Ref. 27) . This is a 1-D model of a 2-D lateral

smolder spread along a horizontal cellulosic roving (in effect a porous

cylinder made up of fibers); air is supplied by natural convection/dif fusion.

The problem is also qualitatively quite similar to a horizontal cigarette

smoldering under natural convection conditions; the model has also been

applied to horizontal smolder spread along blocks of polyurethane foam

wrapped with a cellulosic fabric (28) . For all these cases we have again

l„„ - £ OT7 with both approximately equal to the lateral dimension of the

fuel mass (a general case in the lower half of Fig. 1). This theory is

substantially more complete than any of the preceding models since it

includes fuel pyrolysis as well as oxidation and attempts, also, to

predict extinction limits for smoldering.

The cellulose is assumed to undergo two simultaneous degradation

reactions, one forming a char and the other forming volatiles that

disappear from the system; the oxidation of the char drives this system.

This is analogous to the overall reaction scheme given above but it assumes no char is formed by the pyrolytic route (N^) ; this is an approximation. Note that the amount of char available for oxidation

will depend on the balance between competing reactions.

A planar interface is assumed to divide the cellulose heat-up and

degradation zone from the char oxidation zone; heat from the latter

zone, less heat losses to ambient, must balance the heat requirements of

the former zone in order for a steady smolder solution to exist. If

not, the particular set of conditions falls in an extinguishment region

(transient smolder might exist but is not considered)

With the problem thus split into two parts, the parts are analyzed

separately. The heat-up/degradation zone is treated rather more accurately

than the char oxidation zone. For the former, a 1-D model (neglecting

surface heat losses and radiative transfer) for temperature and species

is solved numerically with various imposed heat fluxes at the artifical

interface. The reaction heats are found to have only a 20-30% effect on

these results so that an analytical solution for zero heat effect is

ultimately used instead. The output is interface temperature and char

285
fraction versus imposed flux. To match this and select a unique smolder

velocity, one needs the available feedback flux from the char oxidation

zone versus interface temperature. Here it is assumed that the char

oxidation zone is isothermal at the interface temperature in spite of

the experimental observation that temperature here varies over a 100-

200° C range. This is the roughest approximation in the model. Heat

generation in this isothermal region can be limited by 0^ supply, oxidation

kinetics or both. The oxidation rate is deduced from the carbon literature

Oxygen arrives at the char surface by diffusion through a natural convection

boundary layer

where 6 is the boundary layer thickness, taken from the literature. The

char is treated as though it is non-porous (on macroscopic & microscopic

scales) and the total heat generation rate is deduced by multiplying the

above reaction rate by an imposed char surface area (estimated from

experiment) . The partial pressure of oxygen at the char outer surface

is obtained from the steady state assumption that the above two expressions

specify equal oxygen fluxes. The char reaction rate specifies oxygen via a stoichiometric coefficient, taken as that for carbon oxidation to CO^;

the reaction heat is also that of this reaction. Finally, the net heat

flux available for feedback is the chemical heat minus radiative and

convective losses as well as a loss through the ash end, rather crudely

estimated. As indicated, this is matched to the pyrolysis zone to get

smolder velocity and peak temperature.

This is a quite reasonable qualitative model of smolder propagation

for this type of over-oxidized configuration (i.e, where there is an infinite reservior of oxygen available to the smolder zone) . It has

1/2

r = FP

ox, s

02,

286
more real physics in it than any preceding model though it still has some major approximations. One might expect that its prediction of

trends would carry over to the cigarette problem mentioned above or to a smoldering fabric or, in fact, to the system studied by Kinbara, et al.

The authors give predictions of the variation of smolder velocity

and peak temperature with oxygen mole fraction and oxygen partial pressure.

They also predict minimum values of these two external parameters which

will yield smolder extinction. The prediction of experimental trends is

good in all cases. In certain cases the quantitative agreement between

model and experiment is quite good; in view of the numerous approximations,

this must be viewed as fortuitous.

Another interesting prediction of the model is that for essentially

all conditions not near an extinction limit the smolder process is oxygen

supply limited. Oxidation kinetics limit only in a narrow zone before

extinction; this is in qualitative agreement with Williams suggested

limit criterion above.

General Comments. From the fire safety viewpoint, the ultimate

goal and justification for modeling of a smolder process is to learn

how to eliminate it; short of reaching this ambitious goal, one at least

wants to know how to lessen the impact of smolder as a cause of fire

deaths and injuries. The above models are only a tentative first step

in this direction. They correlate experimental results, providing an approximate but plausible rationale for the observed behavior. Only

in the last model, however, is there enough detail for one to begin to

discern a route to a lesser smolder tendency. The amount of char formed

is a variable calculated by the model; lessening the amount of char

should shift the extinction limit so that a lesser domain of conditions

permits smolder. Qualitatively, this is an old idea, of course; the

model, however, can quantify the relation between extinction and char

formation. This gives the chemist a quantitative guideline for how

much the char versus volatiles competition must be altered. This is an example of how smolder propagation, which all models show to be oxygen

supply limited rather than chemically limited, is really a chemical

problem. Most solutions to smolder problems will ultimately be chemical

in nature. Another example is in the chemistry of the char oxidation.

287
The model of Moussa, et al. essentially says it affects only the position

of the extinction limit but this is an important relation to quantify;

to close the loop, the chemist must learn how to alter the chemistry of

char oxidation (as well as its formation)

With regard to the char oxidation process, the model of Moussa,

et al. is really rather rough, though less so than the preceding models.

The problem in all of the above cases, however, is that this part of

the problem is non 1-D in character because of the conditions of oxygen

supply. Detailed treatment of a 2-D problem would be premature, at

present; the 1-D cases have not been fully exploited or analyzed.

The 1-D configurations are those limiting cases of forward and reverse smolder indicated in Fig. 1. Fuel bed permeability is high (due

to a very porous structure or an imposed forced flow) so that air and

product gases flow through the fuel. These cases are thus not "overoxidized"

in the sense used above; oxygen reaches the reaction zone from one side at

a rate dictated by buoyancy or by an imposed pressure differential. The

1-D nature of the reaction/propagation process makes a more detailed

treatment feasible though certainly not trivial.

2. Complex Models

The forward and reverse 1-D configurations are at uneven states

of development. That the models exist at all is mainly a consequence

of specific smolder problem areas demanding study. The forward smolder

models, in particular are thus very specialized.

Specialization is also a difficulty in applying to smolder the

literature results from other fields. There are a variety of related

problems, some of which have received very extensive treatment but the

differences from smolder in specific physical and chemical details

typically preclude anything more than some qualitative transferral of

trends. Johnson, et al. (29) present an analytical solution to the

1-D problem of carbon burn-off from a bed of catalyst particles. This

is essentially a forward smolder problem with a very low fuel loading

and a high "ash" content. However, the analytical solution is made

288
possible by de-coupling the reaction rate from the temperature; species

and heat diffusion are also neglected. The model is qualitativelyinstructive in that it shows succinctly how forward smolder, in the

absence of heat losses, is inherently unsteady, with a monotonically

increasing peak temperature. Physically this is a consequence of

regenerative heating of the reactants: gas and solid pass over each

other in opposite directions when leaving and entering the reaction

zone. Heat transfer between them is always such as to feed heat from

both sides back into the reaction zone where it accumulates. This is one of the factors making forward smolder quite different from reverse

smolder

The underground coal and oil shale gasification field is currently

undergoing intensive development. Typically the fuel seam is permeable,

or is made permeable by drilling or explosives, and an exothermic reaction

zone is driven through the fuel, gasifying a substantial fraction of it.

Forward and reverse propagation schemes are used and the heat to drive

the wave comes from partial oxidation of the fuel. The analogy with

smolder propagation is apparent; only the names and the fuels are different.

The logical starting point for models of these processes has been 1-D

descriptions in which the conditions of Equation (1) are assumed to

apply (not necessarily a good assumption in this problem) . The modeling

goals are generally quite different than they are with smolder. The

rate of propagation versus air supply is of some interest but the major

concern is with the composition and energy content of the product gases.

This leads to models which contain rather extensive descriptions of

coal-related chemistry, having as much as a dozen chemical reactions.

Because of specific conditions in such problems, species diffusion is

typically neglected and radiative transfer is included only as a minor

correction to solid-solid conduction; these approximations are not

necessarily good in smolder problems. Typical reports of model development

and results can be found in references 30 to 36. This field continues

to proliferate and bears close watching for qualitative results that may

shed light on the smoldering problem. The models most likely to provide

insights of a useful nature are those less specialized such as ref. 31 or the general performance analyses such as those of wavefront stability

(ref. 33). There has been much less activity directly applied to the

question of smoldering combustion as will be seen.

289
Egerton, Gugan and Weinberg (Ref. 10); Forward Smolder . This model was posed as a first step in the description of smolder propagation in

cigarettes. We have noted previously that the cigarette problem oscillates

in character, falling in the upper half of Fig. 1 during the smoker's

draw and in the lower half between draws. The model proposed is not

complete and it was never solved; nevertheless, the paper in which it was presented was a pioneering effort and had a strong impact on this

field. Arguing from their partial model and from their experimental

results, the authors independently discovered the regenerative heating

effect in forward smolder, qualitatively demonstrated the impact of

switching from forward to reverse smolder, noted the rate-limiting

effects of oxygen supply on smolder and showed that this has powerful

effects on the shape and behavior of this smoldering system, leading

ultimately to an instability in its behavior that precludes uniform

propagation. This was a substantial contribution to the understanding

of smolder propagation.

Summerfield, Ohlemiller and Sandusky (Ref. 37); Forward Smolder . This is a specialized 1-D model of 2-D forced forward smolder in a cigarette; as noted above it falls in the upper half of Fig. 1 since £ equals the tobacco particle size and I » £ (marginally in some

b w r hi conditions). The peripheral paper behavior makes it 2-D. The model is

transient, encompassing ignition but the air flow is constant. Air flow

values are 5-60 cm/sec so that convection is the dominant heat and mass

transport mode; diffusion and conduction are neglected. The model is

further specialized by the fact that it includes a moving step decrease

in side wall flow resistance coupled to the moving thermal wave. This

is a simulation of burn-back of the peripheral cigarette paper, a process

which lets some of the incoming air bypass the oxidation zone. It also

lets essentially all air enter the sides of the cigarette, not the end,

decreasing the regenerative heat transfer effect. This sidewall entry

of air causes strongly 2-D behavior at the base of a real cigarette

coal; this model simulates it qualitatively in a 1-D fashion.

This is the first model to attempt a description of the complete

smolder wave structure, albeit for specialized circumstances. The fuel

chemistry, derived from thermal analysis experiments (heating rates 100X

less than cigarette), includes one step pyrolysis followed by one step

char oxidation (essentially the lower pathway in the above reaction

scheme) . 290
Char oxidation can be kinetically or oxygen- transport controlled. The

model assumes that the conditions in Equation (1) hold, a marginal

assumption for the heating rates and fuel particle sizes involved. Gas

and solid energy equations are considered separately allowing local

temperature differences; this is necessary in forced cigarette smolder.

Radiative transfer between solid particles is described approximately

using the forward-reverse approximation. Radiative losses from the

periphery are included so that the indefinite (and here, unrealistic)

build-up of peak temperatures does not occur. The coupled set of ten

differential equations describing the variable profiles is solved numerically.

Figure 2 shows a typical set of variable profiles in the reaction

region at a time when smolder propagation is nearly steady. The large

local differences in gas and solid temperature are a consequence of the

highly forced smolder and the relatively small specific surface area of

the fuel. Consideration of the direction of heat transport between gas

and solid that these differences imply, together with relative directions

of movement of fuel and gas, should clarify the regenerative heat transfer

effect, always present to some extent in forward smolder. Because of

it, one cannot deduce a peak smolder temperature from a simple overall

energy balance, even in the absence of heat losses.

The oxygen profile in Fig. 2 is peculiar because of the peripheral

air inflow noted above. In the absence of this effect, the oxygen

profile would resemble a mirror image of the gas mass flow profile in

Fig. 2, going to zero near the temperature peaks. Unfortunately, all of

the solutions presented in the above reference include peripheral air

inflow.

The model is reasonably successful in predicting the overall behavioral

trends in this system such as smolder rate variation with air inflow

rate or inflowing oxygen level. The reference shows rather g,ood quantitative

agreement with experimental data but this is fortuitous. The model

predictions are quite sensitive to the details of peripheral

291
air inflow and the 1-D simulation of this 2-D effect is rough. This

model can be viewed as being qualitatively instructive about the details

of forward smolder but there is a need still for a less specialized

forward smolder model that incorporates diffusive effects dominant under

conditions more pertinent to the fire safety field.

Though it is not so apparent from this model study, forward smolder

has another factor inherent in it, in addition to regenerative heat

exchange, that makes it greatly different from reverse smolder. This

is a consequence of oxygen entry from the char side of the smolder zone. The oxygen first encounters hot char and reacts with it, possibly being

fully consumed by the char alone. This would leave no oxygen for the

fuel heat-up zone which can greatly affect the chemistry there. It

also implies that the forward smolder propagation rate is largely dictated

by the stoichiometry of char oxidation. As will be seen, reverse smolder

propagation is dominated by other factors. A detailed model is needed

to investigate these questions and their implications.

Muramatsu, Umemura and Okada (Ref. 38); Natural convection cigarette

smolder . This is a 1-D detailed model of part of a 2-D smolder problem,

i.e., smolder propagation along a horizontal cigarette with a natural

convection air supply. The problem is qualitatively the same as that

of Moussa, et al. above but the goals and treatment are different.

The authors are ultimately interested in the details of smoke formation

in a cigarette; in this model they consider only the pyrolytic/evaporative smoke formation region of a cigarette.

The model is essentially a much more detailed calculation of the same pyrolysis zone prior to the matching interface considered by Moussa

et al. above. The loop is not closed, however, by a prediction of char

oxidation heat feedback. Instead, smolder velocity is an imposed parameter

specifying the rate that virgin tobacco enters the evaporation/pyrolysis

zone from the cold side. The model of this zone is steady-state and

292
requires the simultaneous solution of seven differential equations. The

conditions in Equation (1) are assumed to hold. Tobacco pyrolysis is

described by four parallel gasification reactions whose kinetic parameters

are derived from low to high heating rate thermogravimetry experiments.

The reaction heats are taken as zero as in the model of Moussa, et al.

though the justification is less clear. Water evaporation prior to

pyrolysis is included by employing a semi-empirical rate expression;

it is the only vapor species followed. Gas and solid temperature are

taken as equal; the single energy equation allows heat convection and

conduction plus radiative and convective losses from the periphery. For some unclear reason, sensible heat carried out by vaporized species from

the tobacco is ignored. Radiative transfer is implicit in a temperature

dependent thermal conductivity. The model equations are integrated

numerically from the cold end and the resulting temperature and total

density profiles compared with experiment. Something akin to the cold

boundary difficulty (39) is encountered here but is not fully discussed.

In the zone treated, density falls to about 35-40% of its starting value

and temperature rises from ambient to about 600°C; all vaporization reactions are essentially followed to completion.

Agreement between experimental and calculated density profiles is

generally quite good. The effects of model parameters on these profiles

is intuitively plausible. This is a successful model as far as it goes

but the authors will have to add considerable complexity to reach their

ultimate goal of smoke formation analysis in forced draw conditions.

Ohlemiller, Bellan and Rogers (Ref . 40); Reverse Smolder . This is a 1-D, time dependent model, of downward smolder through a flexible

polyurethane foam material against a buoyant or forced air upflow. It

is essentially a model of the fully 1-D reverse smolder limiting case

shown in the upper half of Fig. 1. The model is suggested by the 2-D

process of smolder spread through upholstery or bedding. A nearly 1-D

region of spread would exist along the centerline of downward/outward

spreading hemispherical smolder zone in a thick bed of fuel. The total

problem of smolder in upholstery or bedding falls into the lower half of

Figure 1 since I equals the cushion or mattress thickness and £ - ft CTT . FE FE Sw

Experimental comparisons are actually with 1-D forced flow configurations

293
(11) ; in this case £_„ is of the order of the cell size in the polyFE urethane and the problem clearly falls in the upper half of Fig. 1.

The behavior of the polyurethane fuel is rather problematical.

Both conditions in Equation (1) are assumed to hold in the model but

there are indications that the second (pertaining to diffusion) fails

at certain stages. Char formation in this material requires oxygen but

this gas has very limited penetration into the original polyurethane

"particles" which have no pores. Thus, char forms on the exterior while

the interior pyrolyzes and vaporizes; the final porous char is open

enough to satisfy both conditions in Equation (2) when it oxidizes. No

attempt was made to account for the complex details of the initial char

formation/ pyrolysis process since this would have required a 2-D treatment

of the condensed phase. An approximate kinetic description in terms of

two overall steps (char formation, char oxidation) was obtained on the same physical foam structure using thermogravimetry; it fits a limited

set of conditions that do not fully match the smolder situation. The

most likely consequence is an incorrect calculation of the amount of

char formed (overestimated)

Another difficulty with the chemistry is treated heuristically

Thermal analysis gives no information on the oxygen stoichiometry of the

overall reaction stages. Moussa, as well as Sandusky, essentially

solved this by treating the char as carbon; no other reactions consumed

oxygen. Here both overall reactions are exothermic as measured by

differential scanning calorimetry and both consume oxygen. In the

absence of better information, the char oxidation stoichiometric coefficient

was taken as (Q^/Q-^) times the char formation stoichiometric coefficient,

where Q is the reaction heat. The char formation stoichiometric coefficient was adjusted until the overall equivalence ratio from the model solution

at one condition was in the right domain. This assumes constant heat

output per gram of oxygen which is an approximation, at best, for smolder.

294
Physically the model is fairly complete. Air flows up toward the

descending reaction zone as a result of buoyancy or forced convection.

Oxygen convects and diffuses toward the reaction zone. The gas phase is

taken to be quasi-steady because its characteristic time is much less

than the condensed phase; this approximation would distort rapid transients

only. The gas and solid temperatures are locally equal, a very good

approximation for reverse smolder in a high specific surface area fuel.

Heat from the reactions can accumulate, be convected, conducted or transferred by radiation; this last is treated with the forward/reverse

approximation. The set of nine time and space dependent differential

equations is solved numerically.

The model is semi-quantitatively successful in predicting observed

reverse smolder trends and parameter values. Smolder velocity is of the

right magnitude; it and peak temperature increase with air flow or 0^

level at approximately the correct rate. Another correct prediction by

the model is that the oxygen/fuel equivalence ratio of the smolder zone increases with supply; this is a distinctive feature of reverse smolder that allows it to adapt to very low supply rates. The model

has definite deficiencies; it substantially underestimates total fuel

gasification and peak temperatures are some 75°C below experimental

values. Part of this is due to the inadequate description of the polyurethane

chemistry; the model will be tested further by the author on a cellulosic

system with fewer complications in the chemistry.

Figure 3 shows some of the variable profiles at a particular time

when the system is fully ignited and is propagating under the diminishing

influence of the igniting heat flux at x = 0. In comparing this reverse

smolder wave structure with the specialized forward smolder case in Fig.

2, one should recall the differing relative directions of movement of

smolder zone and gas flow inherent in the two configurations. Quantitative

comparisons of peak temperature or smolder velocity are deceptive because

of drastically differing air supply rates, about 150X greater in the

forward smolder case. Comparative experiments for the same fuel and air

supply (12) show that forward and reverse smolder temperatures are comparable but that forward smolder propagation is an order of magnitude

slower

295
Note in Fig. 3 that the oxygen is now present on the fuel heat-up

side of the wave, affecting the chemistry there. Its presence there has

another consequence. As soon as an element of fuel reaches a reactable

temperature, it will do so. This cuts off some oxygen to the remainder

of the reaction zone and, in effect, moves the zone toward the oxygen

supply. In other words, this reverse smolder wave propagates at a rate

determined by heat transfer to the virgin fuel and it can leave behind a varying amount of unburned material. The rate at which heat is generated

and made available for transfer is dictated by the oxygen supply so, ultimately, this smolder process is also oxygen controlled.

An important consequence of the tendency for reverse smolder to

leave fuel behind is that it provides insulation to the reaction zone. When

one looks for a domain of non-self-sustaining smolder, the bounds of the

domain depend on the duration of the igniting heat flux. If the flux is

sustained long enough, the reaction zone manages to propagate inward and

insulate itself more and more, finally becoming self-sustaining. This

kind of realistic complication to the question of extinction limits

cannot be handled by simpler steady-state smolder models.

Conclusions

Smoldering combustion is not a well-characterized process. Certain

salient features, such as its oxygen limited character, are widely

recognized and reasonably described though almost always in highly

specialized models. While such models are always of value if they

correlate a set of observations, in general there has been too much

attention devoted to devising a model describing some very limited set

of parameter studies and very little attention devoted to ascertaining

what aspects of the process might be exploited in efforts to control

it. As with flaming combustion, the most practical means of control

will very likely be chemical in nature. This implies two things.

First, much more will have to be learned about the chemistry of smolder

what governs char formation and reactivity, what is the nature of low

temperature exothermic reactions in polymeric fuels, what are the key

296
details of char oxidation. Second, models incorporating tractable

descriptions of these chemical processes need to be developed and studied

in an effort to clarify the context in which this chemistry occurs and

to quantify the sensitivity of the overall smolder process to changes in

individual chemical "steps". It may well be that inhibition of one "step" in the process, e.g., char formation, is more effective than

inhibiting another such as char oxidation. That is, modeling can help

focus chemical efforts on the most productive approaches to smolder

suppression.

As the various models above imply, the context in which the chemistry

is expressed (i.e., the temperature range, heating rate, oxygen level)

varies with the problem at hand; this, of course, affects the chemistry.

Models inclusive enough to help clarify some of these overall chemical

effects must inevitably be physically simplified. The two fully 1-D

limiting cases of Fig. 1, i.e., 1-D forward and reverse smolder, are the

logical starting points. While they do not necessarily bracket the full

range of behavior that might be exhibited in realistic multi-dimensional

smolder problems (especially those that fall in the lower half of Fig.

1) , they do represent opposing poles of a sort which can be identified

to varying degrees in real world problems. A comparative study of

forward and reverse smolder for the same fuel under the same conditions

would provide an excellent qualitative base from which to assess the

interaction of chemical and physical aspects of smolder in realistic

configurations. A preliminary experimental study along these lines of

overall smolder characteristics will soon be available (12) . The 1-D reverse smolder model discussed above is available, although possibly in

need of some refinements; a forward smolder model adapted from it is

being developed (41)

There is a need for more information on the physical, thermal and

chemical structure of propagating smolder waves in realistic problem

configurations. Since the early work of Palmer (5) and Egerton et al.

(10) there has not been a great deal of work in this area. A notable

exception is the work of Baker (43,44) which has had great impact on the

cigarette smolder field.

297
Figure 4 is an example of some recent results obtained by the

author on the thermal structure of a 2-D smolder wave propagating horizontally through an IS cm layer of cellulosic insulation (wood fibers)

This is the problem of Cohen and Luft on a larger scale.) This system

is still under study but it appears to be driven by the combined

exothermicities of char formation and char oxidation and is largely

forward smolder in character; this last is due to predominant, but not

exclusive, supply by diffusion from above. The point to note here is

that real 2-D or 3-D problems do introduce considerable additional

complexity and ambiguity of interpretation. The concepts to be quantified

by the 1-D models discussed above do indeed seem qualitatively applicable

here but this is an underdeveloped area and one must move with caution.

The caution is increasingly needed as diffusive transport processes

in the fuel element become more difficult. Little is known in the area

of smolder propagation in fuels where the conditions in Eqn (1) fail

completely; available data (9,17,24) are suggestive only. The only

complex model the author is aware of which resembles this case assumes

zero fuel permeability (45) and a single reaction at the gas/solid

interface. It is idealized in other ways as well but could provide some insights for such problems as wood smolder. Any further modeling efforts

here should be preceded by experiment.

Another key aspect of the smolder problem is largely unexplored,

i.e., transition from smolder to flaming. It is a frequent end result

of the increasing intensity of smolder with increasing air supply as was noted by several investigators (5,13,17,27,28). Exactly what conditions

are necessary for a switch from the dominance of heterogeneous oxidation

to the dominance of gas phase oxidation is essentially unknown at this

point. Since the transition can lead to a sudden loss of life and

property, it requires close study.

298
Nomenclature

pre-exponential factor

laminar flow drag constant

heat capacity

dif f usivity

effective fuel "particle" size

apparent activation energy

pre-exponential factor

acceleration due to gravity

convective heat transfer coefficient

flux of oxygen to superficial fuel surface

fuel thickness

conduction length; l n = V&it where a is thermal dif f usivity

L w

of fuel mass and t^ is the smolder wave passage time

diffusion length; £_ = VD_t where D_ is the effective

D r W r diffusivity of gases in fuel mass

smolder wave width (Cohen and Luft)

mass flux

thermal mass flux = [m^ C^z + m^, (1-e) Cp

]

oxygen partial pressure at superficial surface of fuel

total pressure

299
q - constant with units of heat flux (Kinbara, et. al.)

Qn

- heat release/unit weight of oxygen consumed

R - universal gas constant

r - fuel reaction rate/unit superficial area

r

c - fuel cylinder radius

T - temperature

v - gas velocity

Vg - smolder velocity

Y - ambient oxygen mass fraction

6 - boundary layer thickness

e - fuel bed porosity (fractional free volume)

A - fuel bed thermal conductivity

a

u - gas viscosity

p - density

sub-scripts

A - air

F - fuel

M - condition at max. temp. m - mean of surface and ambient (Moussa, et. al.)

OC - oxygen convection

OD - oxygen diffusion

OX - oxygen

R - reference or ambient state

300
References

1. Bradbury, A. and Shafizadeh, F. , "Role of Oxygen Chemisorption in

Low-Temperature Ignition of Cellulose," Combustion and Flame 37 , p. 85 (1980).

2. Bradbury, A. and Shafizadeh, F., "Chemisorption of Oxygen on Cellulose

Char," Carbon 18, p. 109 (1980).

3. Glassman, I., Combustion , Academic Press, New York (1977), Chapter 9.

4. Clarke, F. and Ottoson, J., Fire J. , p20, May 1976.

5. Palmer, K. , "Smoldering Combustion in Dusts and Fibrous Materials,"

Combustion and Flame I, p. 129 (1957).

6. McCarter, R. , "Smoldering Combustion of Cotton and Rayon," J. Consumer

Prod. Flamm. , 4, p. 346 (1977).

7. Gann, R. , Earl, W. , Manka, M. and Miles, L. , "Mechanism of Cellulose

Smoldering Retardancy by Sulfur," paper presented at Eighteenth Symposium

(International) on Combustion, Waterloo, Canada, August 1980.

8. Cohen, L. and Luft, N. , "Combustion of Dust Layers in Still Air,"

Fuel 34, p. 154 (1955).

9. Kinbara, T. , Endo, H. and Sega, S., "Downward Propagation of Smoldering

Combustion Through Solid Materials," Proceedings of the Eleventh

Symposium (International) on Combustion, The Combustion Institute,

Pittsburgh, 1967, p. 525.

10. Egerton, A. Gugan, K. and Weinberg, F. , "The Mechanism of Smoldering

in Cigarettes," Combustion and Flame , 7_, p. 63 (1963).

11. Rogers, F. and Ohlemiller, T. , "Smolder Characteristics of a Polyurethane

Foam," J. Fire Flamm. , 11, p. 32 (1980).

12. Lucca, D. , "A Comparative Experimental Study of Forward and Reverse Smolder

Propagation in a Cellulosic Material," MSE Thesis, Mechanical and Aerospace

Engineering Dept. , Princeton University, in preparation.

13. McCarter, R. , National Bureau of Standards, private communication.

14. Bowes, P. and Townshend, S. , "Ignition of Combustible Dusts on Hot Surfaces,"

Brit. J. Appl. Phys . 1_3, p. 105 (1962).

15. Ohlemiller, T. and Rogers, F. , "Cellulosic Insulation Material II. Effects

of Additives on Some Smolder Characteristics," to be published in Combustion

Science and Technology.

301
16. Ohlemiller, T., "Cellulosic Insulation Material III. Effects of Heat

Flow Geometry on Smolder Initiation," to be submitted to Combustion

Science and Technology.

17. Ohlemiller, T. and Rogers, F. , "Smoldering Combustion Studies of Rigid

Cellular Plastics," Princeton University Mechanical and Aerospace Engineering

Dept. Report No. 1432, May 1979.

18. Shafizadeh, F. and Bradbury, A., "Thermal Degradation of Cellulose in Air

and Nitrogen at Low Temperatures," J. Appl. Poly. Sci . 23 , p. 1431 (1979).

19. Anthony, D. and Howard, J., "Coal Devolatilization and Hydrogasif ication,

AIChE. Journal , 22 (No. 4), p. 625, (1976).

20. Laurendeau, N. , "Heterogeneous Kinetics of Coal Char Gasification and

Combustion," Prog. Energy Combust. Sci . 4, p. 221 (1978).

21. Mahajan, 0., Yarzab, R. and Walker, P., "Unification of Coal-Char Gasification

Reaction Mechanisms," Fuel 57 , p. 643 (1978).

22. Sestak, J., Sativa, V. and Wendlandt, W. , "The Study of Heterogeneous

Processes by Thermal Analysis," Thermochimica Acta 7, p. 333 (1973)

23. Rogers, F. and Ohlemiller, T. , "Pyrolysis Kinetics of a Polyurethane

Foam by Thermogravimetry ; A General Kinetic Method," to be published in

Journal of Macromolecular Science, January 1981.

24. Sega, S. , "Experimental Studies of Smoldering of Solid Materials,"

Bull. Japan Assoc. Fire Sci. Eng. 25, p. 25 (1975).

25. Sega, S. , "Theoretical Considerations of Smoldering of Solid Materials,"

Bull. Japan. Assoc. Fire Sci. Eng. 25 , p. 25 (1975).

26. Williams, F. , "Mechanisms of Fire Spread," Proceedings of the Sixteenth

Symposium (International) on Combustion, Combustion Institute, Pittsburgh

(1977) p. 1281.

27. Moussa, A., Toong, T. , and Garris, C, "Mechanism of Smoldering of Cellulosic

Materials," Proceedings of the Sixteenth Symposium (International) on Combustion, Combustion Institute, Pittsburgh (1977), p. 1447.

28. Ortiz-Molina, M. Toong, T. , Moussa, A. and Tesoro, G. , "Smoldering Combustion

of Flexible Polyurethane Foams and Its Transition to Flaming or Extinguishment,"

Proceedings of the Seventeenth Symposium (International) on Combustion, Combustion

Institute, Pittsburgh (1979), p. 1191.

29. Johnson, B. , Froment, G. and Watson, C, "Temperature Profiles in Packed

Beds of Catalyst During Regeneration," Chem. Eng. Sci. 17 , p. 835 (1962).

30. Branch, M. , "In-Situ Combustion Retorting of Oil Shale," Prog. Energy Combust.

Sci. 5, p. 193 (1979).

302
31. Kotowski, M. and Gunn, R. , "Theoretical Aspects of Reverse Combustion

in the Underground Gasification of Coal," US ERDA Laramie Energy Research

Center Report LERC/RI-76/4, Laramie, Wyoming, March 1976.

32. Winslow, A., "Numerical Model of Coal Gasification in a Packed Bed,"

Proceedings of Sixteenth Symposium (International) on Combustion, Combustion

Institute, Pittsburgh (1977) p. 503.

33. Krantz, W. , Keyashian, M. , Zollars, R. and Gunn, R., "Stability of

Forward and Reverse Wet Combustion Fronts in Porous Media," paper presented

at Society of Petroleum Engineers 53rd Fall Technical Conference, Houston,

October 1978, SPE Paper No. 7523.

34. Thorsness, C. , Grens, E. and Sherwood, A., "A One-Dimensional Model for

In-Situ Coal Gasification," Univ. of California Lawrence Livermore

Laboratory Report UCRL-52523, August 1978.

35. Dockter, L. and Harris, A., "A Mathematical Model of Forward Combustion

Retorting of Oil Shale," US DOE Laramie Energy Technology Center Report

LETC/TPR-78/1, July 1978.

36. Gunn, R. and Whitman, D. , "An In-Situ Coal Gasification Model (Forward Mode)

for Feasibility Studies and Design," US ERDA Laramie Energy Research

Center Report LERC/RI-76/2, Laramie, Wyoming, February 1976.

37. Summerfield, M. , Ohlemiller, T. and Sandusky, H. , "A Thermophysical

Mathematical Model of Steady-Draw Smoking and Predictions of Overall

Cigarette Behavior," Combustion and Flame 33 , p. 263 (1978).

38. Muramatsu, M. , Umemura, S., and Okada, T., "A Mathematical Model of

Evaporation-Pyrolysis Processes Inside a Naturally Smoldering Cigarette"

Combustion and Flame 36, p. 245 (1979).

39. Williams, F. , Combustion Theory , Addison-Wesley , Reading Mass. (1965), p. 21.

40. Ohlemiller, T. , Bellan, J. and Rogers, F., "A Model of Smoldering Combustion

Applied to Flexible Polyurethane Foams," Combustion and Flame 36 , p. 197 (1979).

41. Ohlemiller, T. and Padmanabhan, M. , unpublished results.

42. Baker, R. and Kilburn, K. , "The Distribution of Gases Within the Combustion

Coal of a Cigarette," Beitrage Zur Tabakforschung 7, p. 79 (1973).

43. Baker, R. , "Temperature Distribution Inside a Burning Cigarette," Nature 247 , p. 405 (1974).

44. Baker, R. , "Combustion and Thermal Decompositon Regions Inside a Burning

Cigarette," Combustion and Flame 30 , p. 21 (1977).

45. Sirignano, W. , "Theory of Flame Spread Above Solids," in Lectures on Combustion Theory, New York University Courant Institute Report COO-3077-153

Spetember 1978.

46. Palmer, K. , Dust Explosions and Fires , Chapman and Hall, London (1973).

303
TABLE I

EXPERIMENTAL CHARACTERISTICS OF SMOLDER PROPAGATION

Ref.

No. Fuel

Fuel/Smolder

Geometry

Air Supply condition/rate

Maximum

Temp. (°C) Comment

coal dust (<104u) 1 cm thick layer/ horizontal spread

natural convection/ diffusion 1.7-10 460 bulk density not given

sawdust (75-150u) 1 cm thick layer/ horizontal spread

natural convection/ diffusion

(170) stool, vel. increased with

layer depth; (temp, dubious)

cork dust (<65u) (0.18 g/cc)1.65 cm thick layer/ horizontal spread

forward smolder

flow over top of layer/50-700 —

7.10 -1.8 • 10 790 at 200

840 at 600

smol . vel . increased monotonically w. air vel.

cork dust (<65u) (0.18 g/cc)1.65 cm thick layer/ horizontal spread

reverse smolder

flow over top of not given smol. vel. independent of air vel. above 400 cm/sec

vegetable fiber board (0.27 g/cc)

1.3 cm thick board/ upward spreadnatural convec./diffus. 4.5 10 not given smol. vel. ~2X less if board is horizontal

rolled paper 0.4-0.8 cm dia. cylin./ downward spreadnatural convec./diffus. 8.4-5.0 • 10 not given smol. vel. increased with decreasing diam.

10 tobacco shreds cigarette, 0.8 cm dia. intermittent nat'l 820°C convec./diffus. and (nat'l convec.) (nat'l convec.)

c j j 15 cm 3 forced draw

<.15 <1200°C

(periphery during draw) (draw)

highly transient behavior

cellulose fabric +3% NaCl

double fabric layer

0.2 cm thick/horiz.

spread, weakly forward

smol.

flow over exterior, 10-25-770 smol. vel ., te:np. dependent

on additives

11 flexible polyurethane

foam

nearly 1-D/reverse

smolder

uniform flow through foam/0.15-0.45 —

1.0-1.8 • 10 smol . vel . al so increased with increasing Z 0^

12 celluloslc loose-fill

insulation (wood fibers)

1-D/reverse smolder uniform through fiber bed/0.04-0.75 —4.5 • 10 to

3.7 • 10"2 430-640 smol. vel., temp, increased monotonically w. air flow

cellulosic loose-fill

insulation (wood fibers)

nearly 1-D/forward

smolder

uniform through fiber 1.0 to 2.5 • 10 bed/0.15-0.48 —

535-595 smol. vel., temp. Increased monotonically w. air flow

304
Figure 1

Classification of Smolder Problems

i, « I, FE '"SW (effective fuel element J

much smaller than

smolder wave thickness)

Limiting Case ; Air flow and smolder wave

parallel (forward smolder)

General Case:

Vp £fe

SW

0„ ' ?

V

0 0 » 1

AIR

FE - SW

(effective fuel element

comparable to or larger

than smolder wave

thickness)

Airflow & smolder wave intersect at arbitary angles; no restrictions on SL,'CP'

Jl^p except that they are

"FP

V

(eg., cigarette during draw)

Limiting Case : Air flow and smolder wave

anti-parallel ( reverse smolder ) same

AIR

-J

Limiting Case : Airflow and smolder wave

parallel (forward smolder)

General Case:

FE

'SW

/ '

/ /

/usually

2, 3-D

since

< 1

AIR

{

Airflow and smolder wave intersect at arbitary

angles; no restrictions of £ CE : I except that

they be < I (e.g., horizontal spread in a layer

Fh

of loose-fill insulation)

Limiting Case : Airflow and smolder wave

anti-parallel ( reverse smolder )

t 1

AIR

same

305
.03-

.02-

STEADY DRAW MODEL PROFILES IN SMOLDER ZONE

21 SEC AFTER IGNITION

.05

.04-

.01-

.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75

DISTANCE ALONG SMOLDER ZONE. CM

Figure 2. Calculated profiles in forward

smolder zone of a cigarette with steady

draw air flow of 32 cm/sec; smolder

velocity = 0.15 cm/sec.

DISTANCE FROM TOP (cm)

Figure 3. Calculated profiles of a reverse

smolder zone propagating through a flexible

polyurethane. Air flow velocity = 0.2 cm/sec;

smolder velocity = 9.8 x 10~ 3 cm/sec. Radiative

flux of 0.20 cal/cm2 sec persists at top of fuel

(left end in figure)

306
cd & iH 60 u o

4) t-l

n) 4-i

I

ca oi - e

C 41 O H

•H

cn so

4-1 tfl i—I a, • 3 o w u

ai a t u

u . .-i tu i n) -a

4->

(0 ^3 oH C

d o

4) 4-J a n) X 4->

I

• 13

01

01 4-> u tn 3

60 P

•H I

a) a

o 01

0 ou

1-1 01 tH

s-i .h 3

4-1

a) C

4-1 C to O -H N

•H &

V4 O

O .H

U-i

O & CL 4J e &.

•H 0)

!J -O

41&, T3 3 01

W i-H

41 4) .H 3

•H M-l

4-1O «-t n o

p. &

S 41 •H>

cfl 01 C 0

307
THERMAL PROCESSES IN THE SMOLDERING OF WOOD

by

Takashi Handa* , Shuj i Yoshizawa*, Masahiro Morita**,

Masayoshi Fukuoka* , Hidetoshi Tsushima*, Yoshinori

Hashi zume* , and Takashi Nakamura*

* Department of Applied Chemistry, Faculty of Science,

Science University of Tokyo

** Department of Applied Mathematics, Faculty of Science,

Science University of Tokyo

1-3 Kagurazaka, Shinjuku-ku, Tokyo, Japan, 162

ABSTRACT

The oxygen consumption of wood was studied in correlation with

its structural change due to thermal relaxation of the hydrogen bond

network supporting the system. From X-ray diffraction and viscoelastic studies, it was found that the thermal motion in the amorphous

part of wood fibril was optimally activated at around 190°C and the

collapse of wood structure through thickening of fibril occurred at

around 220°C due to the thermal relaxation of interlamellar bonds.

It was also found that there was a linear correlation between the

elongation in crystallite part and that in amorphous part toward Ldirection i.e. approximately along fibril axis, but a break at around

220°C with regard to R-direction. The latter change brought about

a critical break in the relation of oxygen consumption rate with

elongation of size toward both directions. Therefore, the regime

of temperature governing the reaction can be said to be dual demarcated at around 220°C. Lignin was found to play the single most

308
significant role for the oxygen consumption in the first regime.

There was also an indication of an approximate coincidence in the

values of the apparent activation energies between oxygen consumption rate and disclosure of hided sites with a correspondence to the

weight loss rate. The disclosure of hided sites in the second regime

above 220°C must be governed by a delay in the amorphitization of

crystallite part with temperature resulting in an indication of a quasi first order or first order rate in the kinetics of weight loss

reactions. Therein, both values of apparent activation energies

in the first regime may be sustained with a correspondence to the

weight loss rate in the temperature range 130-280°C provided that

oxygen consumption occurred only by the disclosure of hided sites

in the amorphous part which was extented by a collapse of crystallite

part. Secondly, the effect of moisture in reducing the hazard for

the spontaneous ignition of wood during its thermal aging was discussed

with regard to the role of lignin and the state of arts of moisture

in wood. Finally, the calculations were made on-the basis of the

first order reaction rate utilizing the revised equation . Thereby, it

was assumed that the weight loss proceeded in a complex way through

the formation of char(l) which was made from cellulose by a transfer

of nascent oxygen from the thermal decomposition of the oxygen adducts

of active ingredients in lignin at higher temperature.

309
INTRODUCTION

We have studied so far on the thermal change in the physical

properties of wood-polymer alloys in correlation with those

pertinent to wood itself

^ ^ . The objective of these studies

was originally from different prospect for the confrontation with

the deformation and rupture of the irradiated products by thermal

strain due to internal heat evolution in the graft-copolymerization

of synthetic monomers with lumber or a heap of fluffy cotton by

y-ray processing. A critical change occurred in the tangential

direction of wood dimension at around 220°C associated with an

indication of a significant break in its dynamic modulus which

was originated from the initiation of molecular motion in the

amorphous region at around 180°C leading to the scission of cellulose chains in cellulosic fibrils at a high temperature. Abe

and Hirata have pursued the performance of fire retardants in

wood system^-' , As a related study, Hirata reported on the

thermal scission of molecular chains of -genuine cellulose in vacuo

elucidating the mechanism in the possibility for the scission of

molecular chains even at a temperature lower than 220°C ^ .

Hence, we may allow to propose that the thermal relaxation of

the tight hydrogen bond network supporting the wood system must

incur the penetration of oxygen into the cellular system and

as a consequence, will accelerate the chain scission besides the

genuine thermal process producing levoglucosan . Kosik et al.

reported that the oxygen consumption revealed at around 150°C^^^"^

We also probed the situation in the oxygen consumption in connection

with the thermal deformation of wood and cellulose structure covering

the range of temperature from 100°C to 220°C with regard to the

preparation of thermoresis tive wood and base panel of printed circuit

310
This is firstly because of the doubt as to whether the genuine

thermal process had really dominated the phase of thermal deterioration of wooden and cellulosic materials in this range of temperature or the specific oxygen- affinity attributed to the chemical character of some ingredient governed the phase by making a cause for the

preferential break of the tight hydrogen bond network and secondly,

as to whether the latter character can really be one of the important

causes for the incidence of the spontaneous smoldering burn at around

the center of a pile of wood tips and saw dusts, and even in wood

cores far below their nominal ignition temperature after exposure

to hot environments with a long lapse of time.

The present paper deals first with the correlation between the

thermal processes and the oxygen consumption revealing in wood and

secondly, with the spontaneous smoldering ignition of thermally aged

wood core

EXPERIMENTALS

(1) Materials

Veneers used in the study were of rotary-cut beech 0.65mm

thick which were carefully selected from factory products of similar

quality. Filter paper (Toyo Filter Paper No. 2), cellulose film

(Cellulose Tubing by Visking Company), avicel SF, xylan, and lignin

were used as the reference materials of wood. All samples were

oven-dried in vacuo at 80°C for 30 hr, and then maintained in the

desiccator with phosphorus pentoxide in vacuo..

(2) Delignification of wood

Delignified wood was prepared by the sodium chlorite method.

The detailed procedures were as follows: ca. 30ml of distilled water

311
ca. 0.1ml of acetic acid, and ca. 0.3g sodium chlorite per lg of

wood were added to the specimens. Then, the system was heated at

70-80°C for 1 hr. After then, another ca. 0.1ml of acetic acid

and ca. 0 . 3g of sodium chlorite were added to the system per lg of

wood. The heating was continued at 70-80°C for another 1 hr.

After 6 times of chloriting processes at maximum in total, the treatment was washed with cold water and then dried in vacuo.

(3) Measurements

The dynamic modulus E' and the loss modulus E" of the specimens

were measured by Vibron DDV-n. The measuring temperature was

raised from room temperature to 300°C at the rate of l°C/min.

Although E' and E" of specimens were measured in air, the contribution of a slight amount of moisture to E' and E" was not recognized

during measurement at the higher temperature range over 100°C.

X-ray diffraction patterns of the pulverized specimens were

measured at room temperature for the range from 5° to 35° values

of 29 using Ni-filtered Cu-Ka radiation at 35kV and 20mA.

The moisture content (M.C.) of the specimens was controlled in

desiccators over two weeks at room temperature under different

standardized relative humidity (R.H.) using several kinds of solution

of inorganic salts. The M.C. of the system was adjusted to be kept

almost constant during measuring excluding the effect from the environmental humidity. Thereby, those data within the allowable

deviation of M.C. below 0.21 between before and after the measurement

were only adopted, particularly for those samples with an extremely

low and high M.C. For the samples within the allowable deviation

of moisture, the averages of M.C. before and after the measurement

were taken in specifying the M.C. samples. The instrument for the

312
measurement of the dielectric properties was equipped with a bridge

type transformer TRS-10C (An do Electric Co., Ltd.) and an electrode

which was capable to cover the measuring temperature range from -196°C

0°C. The dielectric constant e' and the loss factor e" were measured

along the radial direction of the specimens at each measuring frequency from 30Hz to 1MHz.

Oxygen consumption of samples was determined according to the

procedure of W.L.Hawkins et al/ 14 ^15 ^ in which the amount of oxygen

reacting with the samples was measured volumetrically . The pressure

of oxygen inside the line was controlled at 760 mmHg by meas of a manometer. Samples weighting 0.5g were placed in glass tubes along

with lOg of Molecular Sieve, Type 5A.

RESULTS AND DISCUSSION

(A) Oxygen Consumption and Thermal Deformation of Wood Structure

(a) Oxygen Consumption Below the Nominal Ignition Temperature

The situation in the oxygen consumption of wood and its ingredients were studied covering the range of temperature from 100°C

to 220°C in connection with the thermal deformation of wood structure.

The test specimens were beech veneers (Fagus crenate Blume) which

we used in the measurements of the dynamic and the dielectric properties of wood. Thereby, L- , T- , and R-samples meant those veneers

which were cut out with size of 50 x 5 x 0.65mm and 34 x 34 x 0.65mm

by taking the longest perimeter toward the corresponding direction

of wood respectively. It should be noted hereby that the beech

wood is consisted of cellulose, hemicellulose , and lignin approximately in a weight ratio of 2:1:1. Fig.l shows the time - dependent

variation in the oxygen consumption of wood, delignified wood, and

313
some of those ingredients comprising the wood system at 200°C in

the genuine oxygen atmosphere. It is obvious that lignin possesses

the highest affinity with oxygen being subjected to the high reactivity of its unstable components. Handa et al . elucidated that

those unstable components of lignin on the inner surface of vessels

had extensively terminated the propagating radicals of growing polymer

chains from irradiated radicals in the interior of wood cell through

recombination process in the manifacturing of wood-polymer alloys

under the electron beam irradiation . The next are mannan and

xylan in hemicellulose comprising the amorphous regions of wood

fibrils in combination with cellulose whereas the cellulosic system

either highly crystalline (Avicel) or lowly crystalline (Visking

tube) only exhibited a poor reactivity with oxygen in this range of

temperature. There was an indication of a fair coincidence of the

observed amount of oxygen consumption in wood with the calculated

one on the basis of those in lignin, delignified wood, mannan and

xylan taking the weight ratio of cellulose, hemicellulose, and

lignin as 2:1:1. Therefore, it can be said that about 751 of

oxygen consumption in wood was occupied by lignin leaving about 80%

of the rest 25% for hemicellulose. Therefore, it is suggested that

although there must be another kind of scission endorsed by oxygen,

almost of all scission of cellulose chain below this temperature

must be initiated by a genuine thermal process producing levoglucosan

Fig. 2 shows the situation in the oxygen consumption of wood with hot

bath temperature. The Arrehnius plot of the initial rate of oxygen

consumption vs 1/T gave approximately a straight line. Its slope

value of ca. 24kcal/mol was given as the apparent activation energy

of oxygen adsorption in the genuine oxygen atmosphere. A- similar

314
value of ca. 27kcal/mol was also given for that in air with a decrease in frequency factor. Those values laid close to the value

of 26 . lkcal/mol given by Kinbara as the activation energy of the

f 1 7

weight loss rate of saw dusts in its spontaneous smoldering burn^ . However, being evaluated with the same value of frequency factor,

the latter value in air converted to ca. 30kcal/mol. Fig. 3(a)

shows the effect of intermixed nitrogen in oxygen consumption at

200°C. There was an indication of an approximately linear relation

between oxygen consumption rate and oxygen partial pressure. Fig.

3(b) shows the correlation between the oxygen consumption and

the weight loss of the samples at 200°C in the genuine oxygen atmosphere. There was an indication of a linear correlation between

the weight loss and the amount of initial consumpt ion . Accounting

for the atomic ratios of C and H to 0 in the gasified fraction on the

basis of the lost weight of H, C and 0 as a sum of the weight of

each atom in the lost - fraction and adsorbed oxygen , it was found that

the atomic composition ratio in the gasified fraction were uniquely

of H-^Cj-Og irrespective of reaction time. Thereby, the contents of

H, C and 0 in wt% were 5.4%, 47.81, and 46.81 for the untreated

samples, 5.0%, 49.2%, 45.9% and 4.4%, 50.2%, 45.4% for the samples

exposed to oxygen for 4 and 12 hr, respectively. The content of

carbon in the exposed sample increased scarcely with time whereas

the contents of hydrogen and oxygen decreased. As a result, it

can be said that in a sense, the oxidative degradation proceeded

uniformly irrespective of an indication of the breaking in the

variation of the oxygen consumption with time. Hence, we may allow

to infer that only lignin reacted with oxygen and there must be a

delay of time between the adsorption of oxygen and its release in

315
the gasified fraction. That delay seems to be enhanced in the

oxygen consumption at a temperature lower than 180°C with an indication of a scarce recovery in the oxygen contents of the systems and

the increase of carbonyl groups in the infrared spectra.

Fig. 4 shows the pronounced pattern of such delay as reflected

in the differential weight loss which was promoted in the higher

range of temperature under oxygen- rich environment. Thereby, a fair

faster elevation rate of hot bath temperature of 2.5°C/min was taken.

As a result from the decomposition of the AW-Temperature diagram by

curve resolution, five phases appeared in the change of AW vs temperature of the thermal decomposition of wood in the nitrogen atmosphere containing scarce oxygen. Therein, AVL.. was a difference

between the sample weight at a temperature T^ and W.. at T.. namely

AW^jEW^-W.. and AW-T diagram was prepared by taking always AT^j=4°C.

The first phase must be concerned with the thermal decomposition of

hemicellulose , the second and third ones with cellulose, the

fourth one with lignin, respectively and the fifth one is presumed

to be from the charred residues. Similarly, five phases appeared

in the oxidative thermal decomposition in air. Particularly, the

second and third phases are suggested to come from the decomposition

of cellulose in the scheme as Dr. Roger and Prof. Dr .Ohlemiller proposed^ 18 \ It seems likely that as the oxygen partial pressure

increased, the oxidative decomposition was promoted and the diagram

revealed apparently to be consisted of two major peaks by the shift

of third, fourth and fifth peaks to the lower temperature side due

to the accelerated charring of the oxidized products of lignin -to

oromote the scission of cellulose chain by the supply of nascent oxygen from the decomposition .of' the former under the oxygen-rich atmosphere.

316
(b) Thermal Change in Wood Structure

It is generally accepted that the thermal change in wood

structure can be attributed first to the local relaxation of the

tight hydrogen bond network consisted of interlamellar , inter and

intra fibrilar hydrogen bonds to thermal relaxation and secondly,

to the scission of cellulosic chains due to strain coming from

thermal deformation of structure. As the complex pattern in the

thermal changes of wood structure is well reflected on the changes

in various physical properties of wood, it is not too far saying

that we can know the extent to which a certain change occurs by

detecting the change in the corresponding physical properties.

Fig. 5 shows the dilatometric change of wood dimension with

temperature along the longer direction of test specimens which

were cut out by taking the longest perimeter toward L- , and Tdirection of rotary-cut beech lace veneers, respectively. There

was an indication of the system for the inflexion of the thermal

expansion toward R-direction at around 220°C and also the compensated

inflexion to promote the elongation toward L-direction at around

230°C respectively being in overall resulted in a serious contraction

of volume above 220°C.

Fig. 6 shows the thermal changes in (002) spacing of the cellulose

crystallite and the half width angle of (002) with hot bath temperature by X-ray diffraction^. Thereby, the latter represents

changes in the fibril orientation suggesting that the thickening of

fibrils occurs at around 220°C in a way to take the maximum fibril

angle due to the thermal relaxation of interlamellar hydrogen bond

system. Comparing the macroscopic dilatometric change in Fig. 4 with

the microscopic one in Fig. 5, it was found that there was an :..

317
excellent linear correlation between the dimensional change in the

crystalline part as represented by the elongation of (002) spacing

and that in amorphous part as represented by the elongation of sample

toward L-direction. However, there was a revelation of break at

around 210°C in the linear correlation with regard to T-direction.

Further, the elongation of the (002) spacing was particularly

promoted above 230°C being corresponded with the enhanced elongation

toward L-direction. The promoted elongation must be caused by the

random scission of cellulosic chains revealing eminiently above 230°C

even in vacuo with an indication of levelling off degree of polymerization (DP^) of ca. 600 after 3 hr at around that temperature and

DPro of ca. 200 after 2 hr at around 260°C. Thereby, it should be

noted that the split fractions must be recrystallized into microcrystallites by cooling because of an indication of the elevation

in the crystallinity index of the test specimens after the exposure

(19) to repeated cycles of heat cure below 220°C^ 3J

. Above 250°C, the

enhanced stretching occurs toward L-direction in a way so as to

reduce the fibril angle by the dislocation leading to the rupture

of crystallite due to the thermal strain from the peeling motions

of the defolded tails which are entangled with the chains in the

amorphous part. The thermal motions of those molecules consisting

f amorphous part of wood ate activated optimally at around 190°C

as will be referred to in the succeeding discussion.

Fig. 7 shows the correlation between the oxygen consumption

and the dilatometric change in wood dimension. Remembering that

the initial rate of oxygen consumption illustrated a linear

plot vs 1/T and the cellulosic material either highly or lowly crystalline exhibited a poor oxygen consumption at 200°C, the revelation

318
of anomalous break at around 210°C in the increase of oxygen consumption with the elongation of size either toward both L- and Indirections suggests that the corresponding increase in the specific

internal area occurred by the disclosure of hided sites of lignin

and hemicellulose due to an extensive relaxation of interlamel lar

hydrogen bonds sustaining cellulosic fibrils in the temperature

range 210-230°C.

The predicted rupture of hydrohen bond network of cellulosic

fibrils in that temperature range can be said to be substantially

reflected in the break of the dynamic modulus of wood in the temperature range 210-250°C with revelation of the loss modulus peak at

around 220°C for T-samples and the at around 240°C for L-samples

respectively. The thermal behaviors of the dynamic modulus E'

and the loss modulus E" for T-samples at the measuring frequency

of 110Hz, 35Hz, and 11Hz are shown in Fig. 8. Approximately the

same pattern was also observed with regard to the measurement in

terms of the vibrating method. Similar patterns were observed in

the thermal dispersion of the dynamic shear G' and the loss modulus

G" which were measured by torsion pendulum in vacuo at a measuring

frequency of ca. 0.3Hz for L- and T-samples of oven-dried beech

veneers. Fig. 9 shows the variation in the temperature dispersion

of E' and E" with grain angle. The peculiar shift of the indicated

temperature of E" peak is based on the anisotropic character of the

thermal relaxation conforming to the spatial angle between grain and

fibril. Fig. 10 shows the temperature dispersion of E

f of delignified

T-samples. The delignified samples indicate a higher crystal linity

index than that of the ordinary ones by X-ray diffraction. The

temperature dispersion of E' and E" looks like that of the ordinary

319
T-sample. This indicates that although the oxidation of lignin

proceeded considerably in the range of temperature lower than 220°C,

lignin itself was not authentically involved in this phase of structural change. Fig. 11 shows the overall change of dynamic modulus

and the loss modulus of wood (L-sample) at a measuring frequency of

110Hz and in ^ containing scarce oxygen covering the range of temperature from 30°C up to 320°C which is nominated as decomposition

temperature of cellulose by DTA study. An intense decrease in E£

and the corresponding rise of E^ revealed suggesting the collapse

of fibril system.

As a result, togather the results so far^ 5 ^8 ^, eight E" bands

revealed in overall as pertinent to wood (M.C.=1%). They are

summarized in Fig. 12 and are assigned as follows: Band(a) at around

300°C comes supposedly from the defolded and zig-zag bridged short

chains of dehydrated cellulose due to the thermo-oxidative scission

of chain and cross-linking. Band(b) at around 250°C comes from the

decrystall i zing structural change to stretch fibrils being accompanied

by the shrinkage along the T-direction. Band(c) at around 220°C

comes from the degradative structural change to thicken fibrils due

to the thermal relaxation of the interlamellar hydrogen bonds.

Band(d) at around 190°C comes from the transition in the molecular

motion of amorphous cellulose and hemicellulose . The magnified

revelation of this loss band was confirmed by the lower temperature

shift of band(b) and band(c) in the decrystallized samples'^.

Band(e) at around 135°C comes from the deformation in the fibril

orientation by the disorder in its conformation close to the surface

of the cell wall. It was confirmed that a magnified activation of

this loss band revealed due to the thermal perturbation by polymer

320
produced outside the cell wall in polymer-wood alloys . Band(f) at ca. 100°C comes from the dehydration of movable water

associated with the hydrogen bond in wood. Band(g) at ca. -50°C

for ordinary sample (M.C.2%) consists of dual bands. BandCg^) comes

from the relaxation of hydrogen bond involved in the local mode

motion of wood system due to moisture and Band(g2) comes from the

intrisic mode of cellulosic segments etc. Band(h) at ca. -120°C

must come from the rotational motion of the methylol (C^OH) groups

in wood. Therefore, it is allowable to conclude that eight stepwise transitions occur in structural change and transition of wood.

The apparent activation energy for the thermal relaxations of hydrogen bond system attributed to bonds (a), (b) , (c) , (d) , (e) , (g)

and (h) are estimated to be °°, 440 , 160 , 80 , 25- 30, 16 , and ca. 9

kcal/mol, respectively. Those for the thermal relaxations pertinent to bonds (a), (b) and (c) are anomally high. Hence, it is

suggested that the thermal scission of the glucosidic linkage must

occur involving the chemical reaction (dehydration cross- linking

and oxidation) before the system decomposes into single cellulosic

chains. Fig. 13(a), (b) shows the similar changes in the temperatur

dispersion of dielectric constant (e') and the loss factor (e") for

the oven-dried R-sample. It may be allowable to presume the low

measuring frequency (110Hz) represents the rotational motion of

C^OH groups with an indication of the loss peak for the rotational

motion of Ch^OH groups at a temperature close to -110°C (oven-dried)

and the high frequency (1MHz) rather responds with the motion of

OH groups. The former motion begins to be activated thermally at

around 135°C whereas the latter motion begins to be activated at

around a temperature higher than 200°C. The revelation of another

321
e" peak was confirmed at around -40°C due to hydration for R-samples

with M.C. of 1.2%^ 20 ^ (21)

^ p^g > ^4 reveals the higher temperature

shift of the e" peak coming from the rotational motion of Ch^OH

groups for the heat cured samples at 240°C for 1 hr. The increase

in the value of the activation from 9.4kcal/mol to 12 . 8kcal/mol

associated with the higher temperature shift of that e" peak suggests

the possibility for the formation of cross - linking among cellulosic

chains in fibrils which promotes the restriction on the rotational

motion of CF^OH groups exposed to the channel among the folded

chains in the lamella. Fig. 15 shows the corresponding changes in

DTA thermogram. Curve (a), curve (b) , and curve (c) represent the

thermogram of beech veneers in air, ^ with a trace of oxygen and

the well known endothermic ones in genuine Ar environment, respectively. The dotted line associated with curve (a) means the change

in the ratio of CO to CC^ in weight i.e. WC0/WCO2 with temperature.

It was assigned by many authors that the exothermic peak which

revealed at around 400°C in curve (a) came from the combusion of

oxidized lignin whereas the shoulder and peak at around 280°C and

310°C came from the hemicellulose and cellulose. From the change

in WC0/WCO2 with temperature and our foregoing results in the

oxygen consumption of each gradient at 200°C, it is evident that

lignin was oxidized in the lower range temperature and the oxidized

products must be decomposed vigorously at a high temperature around

400°C. As shown by curve(c), the thermal decomposition of wood

in Ar is authentically endothermic throughout the process. Curve (b)

suggestes the initiation of oxidation due to the scarce present of

oxygen at around 150°C corresponding to the relaxation of hydrogen

bond in the amorphous parts. The exothermic peak at around 150°C

322
in the dotted curve associated with curve (b) in rigid line represents

the estimated heat possibly issumed by the oxygen consumption of

lignin which was located close to the surface of cell wall. The

cross-over from endothermic to exothermic of curve (b) revealed at

around 225°C by the penetration of oxygen due to the aforementioned

thermal relaxation of hydrogen bond network in fibrils corresponding

to the E" band(b) and .(c) in the thermal change of E" in Fig. 14.

The higher temperature exothermic peaks at around 300°C in the

dotted curve must come from the oxidation of hemicellulose and

cellulose. It is evident that the oxidation accompanied by an evolution of heat occurred even at a temperature lower than 150°C

with an indication of a scarce loss in weight. On the basis of

the analytical values of oxygen content in the heat cured product,

it is suggested that some chemical changes, say, oxygen bridge

involving the formation of peroxide with unstable components in

lignin must be occurred at a lower temperature besides the oxidation

during the slow elevation of the environmental temperature.

(B) Spontaneous Smoldering Ignition of Wooden Materials

It is evident that only lignin and some igredients comprising

hemicellulose can adsorb oxygen and react with it at a temperature

lower than 180°C. This lower temperature oxidation must be a cause

for the incidence of smoldering burn of wood materials after exposure

to hot environments for a long time in a shape of a bulky matter

or being placed in a state of thermal insulation. Since long time

ago, the spontaneous smolderings of a pile of fiberous materials,

coals, saw dusts and tips have been matters of a well known

discussion, the theoretical elucidation of which was given by FrankKamenetzkii. Also, I should like to remember that Dr. Robertson in

323
National Bureau of Standards had made an extensive contribution to

this area of research. The point taken up in this paper is the

effect of moisture on the spontaneous smoldering burn. Moisture

can participate in the hydrogen bond network and confront with the

oxidative degradation of wood system by shielding the penetration

of oxygen into the cell system. As reported previously, even a small amount of M.C. in an order of 1-3% can reform the authentically

deformed wood fibrils and gave a closest packing structure with an indication of the maximum value of E

1 vs moisture^^. Fig. 16 shows

the state of moisture contained in wood from the dielectric aspect

of study on the temperature dispersion of loss factor for samples

equilibrated to various R.H. below moisture content (M.C.) 10%, the

moisture participates in the cooperative local motion of hydrogen

bonds and above M.C. of 10%, some part of moisture is free from the

f 211 system with an indication of the presence of ice at -40°C l J

. Moreover, it consumes heat in the vaporization. The samples used

in the experiment were spherical cores of Japanese cedar wood with

diameters of 5, 10, 15 and 20cm, respectively. The hot bath (100cm

x 100cm x 150cm) was equipped witlr electric heaters in quartz-glass

tubes on every wall, ceiling and floor being shielded by asbesto

plates so as to reject the direct exposure to radiation from heaters.

The temperature of hot bath was adjusted multiply by a controller

system of the heater voltage. The temperature defference between

ceiling and bottom remained within 0.5°C.

The calculation on the temperature in wood was made on the basis

of the following equations and boundary values:

(i) equation of energy

324
tfvQ'K,(f;-P

where kiSl . J5Mf;_j,^(")

(ii) equation of moisture diffusion

(iii) boundary condition between wood (I) and mortar (II) or

glass-wool (II)

.\ 'vri

' i ct> - Ui)

_ \ r$T l for all boundaries

A is the heat conductivity, D is the diffusion constant, p is the

density of wood, Cp is the specific heat, p v is the density of

moisture, A is the pre - exponential factor, E is the activation

energy for the weight loss rate, Q is the heat evolution per gram

of sample, Q* is the heat of vaporization, is the adsorption rate

of moisture, is the desorption rate of moisture, and 6 is

decomposition ratio of the system at an arbitrary weight W in a quasi

first order decomposition of wood.

As the hot bath temperature was generally adjusted in the range

lower than 200°C and the heating rate was so slow staying in the

range 0 . 2 °C- 0 . 4°C/min , we adopted the present representation in the

equation with regard to the contribution from internal heat generation, assuming that some part of oxygen which was adsorbed by

active components of lignin was rather stored in the system than

completely released back to environment in the gasified fractions.

Even if we adopted the first order rate equation, assuming a faster

325
rate (2-3°C/min), there was no an indication of any obvious difference

in the behavior of the center temperature except some changes in

the values of activation energy and pre - exponential factors being

located close to those value which many authors estimated

covering the higher range of temperature under a faster

heating rate. The experiments revealed two distinctive results,

smoldering- ignition and non- ignition , depending on the balance

between the size of spherical wood core and the environmental temperature. There were indications of stationary values being extended

from 80°C to 110°C in the elevation of the center temperature.

Fig. 17 shows the example for the non-ignition result with regard to

the wood sphere of 10cm in diam. being placed in the hot bath with

a slow heating rate and the levelling off of the elevation in hot

bath temperature at around 150°C. The curves (I) and (II) with rigid

lines are the observed values of the surface and center temerpature

respectively, while the curve with dotted line is the calculated

one. There was an indication of a symptom for some stationary

values in the range from 80°C to 90°C with the elevation of the

center temperature. However, it should be noted that the same

system ignited under a more slower heating rate with a higher levelledoff temperature and a less moisture content. Fig. 18 shows the

example for the spontaneous smoldering ignition at an environmental

temperature far lower than the nominal ignition temperature of wood.

The wood sphere of 10cm in diam. enwrapped by glass wool was used.

Curve(I), curve(II) and curve(III) with rigid lines represent the

temperature in the hot bath, boundary between glass-wool and wood

sphere, and the center of sphere, respectively. The curve (II')

curve (III') with dotted lines represent the calculated values, respe326
ctively. There was also an indication of some stationary values

for the elevation in the center temperature due to the effect of

moisture. Fig. 19 shows the relation between the critical environmental temperature to induce the spontaneous ignition of wood

sphere and the diameter of wood sphere with regart to the calculation

on the basis of the observed values of surface temperature taking

the activation energy as 35.5kcal/mol for the thermal decomposition

of wood issuing the heat ganeration. Therein, the rigid circles

are the observed values and open circles are the calculated values.

Fig. 20 shows the shift of ignition site in the spherical wood core

of 10cm in diam. with the elevation in the surface temperature.

The ignition site moves from the center to,'the surface with a route

as shown in the figure because of the anisotropy in the heat conductivity and diffusion coefficient of moisture in wood. Fig. 21 and

Fig. 22 shows the examples for the revelation of obvious stationing

of the temperature rise due to moisture with regard to the spherical

wood core of 10cm in diam. enwrapped by a layer of mortar with 2.5cm

width and the spherical saw dust blocks of 40cm in diam. The

3 3 latter samples contained moisture 0.2099kg/m and 0.4000kg/m , respectively. There was indication of obvious stationary values

extended from 80 to 100°C in the elevation of center temperature

for wood sphere enwrapped by mortar because of the moisture hydrated

in mortar and no indication of any symptom for the spontaneous smoldering ignition being prevented by a greater heat conductivity of

mortar. After 15 hr, every temperature at the center inner boundary

and surface levelled off and converged to the hot bath temperature

of ca. 150°C. The time - dependent variation in the observed values

327
for the decomposed fraction 6 is shown in Fig. 23. It is suggested

that most of the weight loss was occupied by those of hemicellulose

and lignin considering the weight ratio of cellulose, hemicellulose

and lignin, approximately being 2:1:1. Typical examples for the

stationing due to moisture revealed in the elevation of center

temperature of moistened saw dust block with an indication of a long

terrace of stationed temperature exceeding 80 hr . Thereby, we used

Kinbara's value of 26.1kcal/mol in the computation as the activation

energy for the thermal decomposition of saw dusts v

. The numerical values used in the computation are summarized in Table 1.

Next, we revised the previous equations extending the regime of

temperature in the reaction by assuming two stepwise decomposition

of wood;

[wood] > m

1 [char(l)] + ljjgases]

[char(l)] > m

2 [char(2)] + l

2 [gases]

Following equations were provided:

(i) equation of continuity

(ii) equation of energy

(iii-a) mass fraction of wood

(iii- b) mass fraction of char(l)

where

328
It should be noted hereby that we excluded the effect of moisture

utilizing the oven-dried wood sphere of 20cm in diam. Fig. 24(a)

shows the coincidence of the calculated result with the observed one

with regard to the time - dependent variation of temperature at the

center of sphere. Fig. 24(b) shows the time - dependent variation

of the calculated values for the density of wood, mass fraction of

char(l) and wood at the center. Fig. 25(a) and Fig. 25(b) show

calculated results on the time - dependent variations in the distribution profiles of temperature and density along the radial direction

of sphere. The numerical values of parameters used in the calculation are summarized in Table 2. We feel, it is really our great

honor and privilege that we could borrow the numerical values

estimated by Dr. Roger and Prof .Dr .Ohlemiller for the thermal decomposition of cellulose in air. Thereby, we assumed; the thermal

decomposition proceeded in a complex way in that the thermal

decomposition of cellulose to char (1) occur due to the transfer of

nascent oxygen by the thermal decomposition of oxygen adducts

coming from the reaction of oxygen with the active ingredients in

lignin and hemicellulose in the range of 200-240°C. It should be

noted that the calculated value on the ultimate value of density

after thermal aging coincidenced approximately with the observed one.

CONCLUSION

Smoldering combusion of wood can be characterized to be promoted

by thermal processes in the relaxation of hydrogen bond system lead329
ing to the collapse of its fibril structure with genuine .or oxidative

scission of cellulosic chains. The function of temperature governing the reaction is distinctively divided into two regime demarcated

at around 220°C. The oxygen consumption of lignin plays the most

significant role in the first regime below 220°C being subsidiarily

endorsed by that of hemicellulose . It is suggested that those oxygen consumption are promoted above 150°C depending on the extent to

which the hided sites of lignin and hemicellulose in the amorphous

part are disclosed on the inner surface of cell walls along the

vessel of wood. There was an indication of an approximate coincidence in the value of the activation energy of the oxygen consumption

with that of the activation of the thermal motion of fibril tails

on the surface of vessels with a correspondence to weight loss.

It is suggested that the long time accumulation of heat issued from

those oxygen consumptions must be the most significant cause for

the spontaneous smoldering ignition of bulky wood materials far

below the nominal ignition temperature of wood under a faster heating rate. The role of moisture contained in wood in reducing the

possibility for that type of spontaneous ignition due to oxidation

of the components in lignin must be the rejection of the oxygen

adsorption being hydrated in the hydrogen bonds in those site as well as taking off heat due to evaporation. The smoldering process

in the second regime above 220°C must be proceeded mostly through

the disclosure of hided sites in the amorphous part of wood depending on the extent to which the crystallite part binding the fibril

structure is descrystallized due to the genuine scission of folded

chains. Thereby, the weight loss must occur through disclosure of

hided sites with a correspondence in activation energy and a delay

330
in the amorphitization of crystallites. Comparing the results

of the simulation, it is likely that the decomposition reaction

proceeds in a first order rate under the faster heating rather than

in a quasi-first order rate.

331
REFERENCES

1) T.Handa, I.Seo, H.Akimoto, M.Saito, Y.Ikeda: Proc. 15th Jpn

Congr. Mat. Res., 1972, pl58.

2) T.Handa, S.Yoshizawa, H.Kaido, I.Seo, N.Otsuka, M.Saito, Y.

Ikeda: Proc. 18th. Jpn. Congr. Mat. Res., 1975, pl26.

3) T.Handa, S.Yoshizawa, Y.Ikeda, M.Saito: Kobunshi Ronbunshu,

33, 147(1976).

4) T.Handa, S.Yoshizawa, Y.Ikeda, M.Saito: Kobunshi Ronbunshu,

34, 195(1977).

5) T.Handa, S.Yoshizawa, M.Suzuki, T.Kanamoto: Kobunshi

Ronbunshu, 35, 117(1978).

6) T.Handa, S.Yoshizawa, M.Suzuki, M.Fukuoka, Y . Hashi zume , I.Seo

Proc. 21st Jpn. Congr. Mat. Res., 1978 p304.

7) T.Handa, S.Yoshizawa, T.Nagashima, H.Tsushima, H.Yamamoto,

N.Ebihara: Proc. 23rd. Jpn. Congr. Mat. Res., 1980, p333.

8) T.Handa, S.Yoshizawa, M.Fukuoka, M.Suzuki: Polym. Sci. and

Technol., voll. 11 "Polymer Alloys II", D.Klempner and

K.C.Frisch (Eds), Plenum Pub. Corp., 1980, p263.

9) T.Hirata, H.Abe: Mokuzai Gakkaishi, 19, 451(1973).

10) T.Hirata, H.Abe: Mokuzai Gakkaishi, 19, 483(1973).

11) T.Hirata: Mokuzai Gakkaishi, 22, 238(1976).

12) M.Kosik, M.Micko, R.Domansky: Wood Science, 1, 167(1969).

13) M.Kosik, V.Luzakova, V. Reiser, A.Blazej: Fire and Materials,

1, 19(1976).

14) W.L.Hawkins, R.H.Hansen, W.Matreyek, F.H.Winslow:

J. Appl. Polym. Sci., 1, 37 (1959)

332
15) W.L.Hawkins, W.Matreyek, F.H.Winslow: J. Polym. Sci., 41, 1

(1959)

16) T.Handa, S.Yoshizawa, K. Hatakeyama : J. Appl. Polym. Sci.,

23, 1527 (1979)

17) J.Kinbara: Bull. Fire Prevention Soc . Jpn , 16, 9 (1967)

18) F.E.Roger, T.J. Ohlemiller : Pretext of 5th UJNR Conference on

Fire Research, 1980

19) T.Handa, S.Yoshizawa, M.Suzuki, M.Fukuoka: Proc . 22nd Jpn.

Congr. Mat. Res., p. 223 (1979)

20) T.Handa, M.Fukuoka, S.Yoshizawa: Kobunshi Ronbunshu, 36, 703

(1979)

21) T.Handa, M.Fukuoka, S.Yoshizawa: J. Polym. Sci., Polym.

Phys .

, submitted

22) C.O.Seborg: Ind. Eng. Chem. , 29, 169 (1937)

333
& X1CT

Time ( hr.)

Fig.l Variation in the oxygen consumption on heating of wood and

its ingredients at 200°C.

x, wood; •, filter paper; o, avicel SF; xylan;

D, lignin; A, delignified wood.

334
X10"2

10 1

0 2 U 6 8 10

Time (hr.

)

Fig. 2 Variation in the oxygen consumption on heating of wood at

virious temperature from 150°C to 220°C.

o, 150°C; •, 180°C; A, 200°C; A, 210°C; 220°C.

335
Time (hr.)

Fig. 3(a) Effect of oxygen partial pressure on the variation

the oxygen consumption on heating of wood at 200°C.

336
X10*

40

Time (hr.)

Fig. 3(b) Weight loss of wood corresponding to the oxygen consumption

on heating at 200°C.

337
ATjj=Ti—Tj =4°C

Temperature (°C

)

Fig.

4 Effect of oxygen partial pressure on the variation in the

weight loss rate on heating of wood on the rate of 2.5°C/mi
- 2.0

o 1.0

o

<bcnc

0 ch

E

D

1.0 O

>

--2.0

100 150 200

Temperature (°C)

Fig. 5 Temperarure dependences of the thermal expansion of wood

, L-direction of wood; , T-direction of wood;

, volume of wood.

339
100 200

Temperature (°C)

300

Fig. 6 Temperature dependences of spacing of (002) in cellulose

crystallite and the half angle of (002) representing cellulose

fibril orientation in site at the corresponding temperature,

o, spacing of (002); •, the half value angle of (002).

340
0.2 OA 0.6 0.8 1.0

Thermal Expansion (•/«.)

Fig. 7 Correlation between the initial rate of oxygen consumption

and the dilatometric change of wood.

, L-direction of wood; , T-direction of wood.

341
oO

O

in

CMoo

CMo

inoo ue O ^

in ~2

o. o .0> o

ini ooI o

ini

cd

H

C

CO o - m w i/> • CD ts)

t/> •Hu rH

iH c rH

CD T3 3 O a* e CD

rH

u <+H

N • H6 Ml

CO

C f) c •H

rH 9s Tb 3 <

tt> CO * r> CD N

+J 6 o

rH o rH o

t/)

H #v CD O U CO>

CD >> -a +-> u

CO

d

a>

O CD o P

CD

W ;* a* TJ CD

t/) r-< CD P O m

rH rH

C bo

+-> 13

O c

CO

O •H •H

(h e •M

0)U

P. </> CO in B Sh co

CU o •H CD rH T3 e

oo

•H

Ph

(jUJD/auApJ.iB'fa

342
10

10

E a

Ofc

>*

o

Li

"•""'•^^^

• : o*

0° 0 °;

°°."::

0:11.3°

a:22.5°

o 00 «>o a :45°

67 5°

50 100 150 200

Temperature ( °C

)

250

Fig. 9 Temperature dependence of the dynamic modulus E' and the

loss modulus E" at 110Hz as a function of grain angle of

wood

grain angle: •, G°(L); o, 11.3°; A, 22.5°; A, 45°;

, 67.5° ; x , 90° (T)

343

I

I
10

,0 r

E

u

c

10!

E'

oo

a ; delignified amount 15.5%

o; * 5.2°/e x : * 0%

x-a°°°o

LU 10

8 h

*XXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX x " 0 oc ^HJli

ocooo o oo0 oooooooo ooooooooooo oooo ooooooooo^

A A A A A A AAA AAA AAA A AAA' A A AAA A A A A A ' Aa ,

50 100 150 200

Temperature (°C)

250

Fig.ro Temperature dependences of E'^ and E" at 110Hz of the

delignified wood.

delignified amount: x, 0%; o, 5.2%; A, 15.5%.

344
o

e

to

•*-> a

E

( 3 aiD/9uAp) M 3 ',3

Fig. 11 Temperature dependences of E ' and E" at 110Hz of the L

direction of wood.

345
CT) 00 O O i

( ? ujd/9uAp)„3 ..3

346
.3

Fig. 13(a) Dielectric constant e' for Redirection of oven-dried wood

as a function of temperature at respective frequency.

347

I
..3

(b) Dielectric loss factor e" for R-direction of oven-dried

wood as a function of temperature at respective frequency,

a, 30Hz; b, 110Hz; c, 3Q0Hz; d, 1kHz ; e, 3kHz; f, 10Hz;

g, 30kHz; h, 100kHz; i, 300kHz; j, 1MHz.

348
I 1 I I—

CD in >t 00 CN

o o o o o o o

o o o o o o o

..3

Fig. 14 Temperature dependence of the dielectric loss factor e"

R-direction of oven-dried heat-treated at 240°C.

a, 30Hz; b, 110Hz; c, 300Hz; d, 1kHz , 3kHz; f, 10kHz;

g, 30kHz; h, 100kHz; i, 300kHz; j, 1MHz

349
u

__i i . i I 0

100 200 300 400 500

Temperature (°C )

Fig.l§ DTA thermograms of wood.

a, in air; b, in N

2 with a trace of 0

2

; c, i

350
-200 -150 -100 -50 0

Temperature (°C )

Fig. 1-6 Temperature dependence of log e" at 30Hz for R-direction of

wood containing various amounts of moisture,

x, oven-dried; ©, 0.7%; o, 4.2%; •, 8.7%; ©, 13.5%;

A, 18.5%; D, 24.7%.

35l
IS * - - •

calculated

observed

5 10

Heating duration (nr.)

The variation in the

center temperature for

spherical wood core of

10cm in diam.

Fig. 17 Variation in the center temperature for spherical .ood

core of 10cm in diameter.

352
J I L 0 5 10 15

Heating duration (hr)

The temperature rise at center of

wood sphere and boundary between

wood and glass wool for wood sphere

of 10cm in diam. enwrapped by

glass wool.

Fig. 18 Temperature rise at center of wood sphere and boundary

between wood and glass-wool for wood sphere of 10cm in

diameter enwrapped by glass-wool

353
OO

— o

"5E

tj

Of £C

<TJ Ofa a> i t

CD

4->

13C

CO0

!h3

+-» cde

CD +J

43PO

XI

+Jouo

F3

<I> CD M

CD X>CO

CD

>-< ou

•H

PL,

CD

CD

(X

tfl

t3OO

CD ! +-» CDe

cd •HT3

354 I 1
center surface

0 12 3 4

Radial distance (cm)

Shift of ignition site with

surface temperature

Fig. 20 Shift of ignition site with surface temperature.

355
0 5 10 15

Heating duration (hr)

Time- dependence temperature rise at | the center of wood sphere and in the

boundary between wood sphere and

mortar.

Fig. 21 Time - dependent temperature rise at the center of wood sphere

and in the boundary between wood sphere and mortar.

356
0 20 AO 60 80

Time( hr)

Fig. 22 Thermal diagram of the wood sphere for the case of the

arbitrary size as illustrated in figure.

357
Fig. 23 Variation in decomposition rate of wood with heating duration.

358
I -—^fc I o o o

o o

CM *- (Do) ejn^pjadujai

.24(a) Time -dependent variation of temperature at the center

of sphere. 359
o

\ 1 < 01

Ott_

01 -C

CI

"O

O

O

o

o>c

at u

a*

i—

\i^ at \*~

\

•

•

• o cr

i V*

i

•\ i v

Density

L U IT) CD

^

8 (Oo) ejnpjadujei 8

OO

§ (^/6>j ) Ajisuea 2

8

CM

Fig. 24(b) Time- dependent variation of calculated values for the

density of wood, mass fraction of char(l), and wood of

the center.

360
Fig. 25(a) Distribution profiles of temperature along the radial

direction of sphere.
Distance (cm)

Fig. 25(b) Distribution profiles of density along the radial

direction of sphere.

Table 2. Thermal parameter for the computer simulation

Specific Heat (kcal/kg.deg) c 0.41

Thermal Conductivity (kcal/m.hr .deg) *// A J.

1.5 x

10~*

7.5 x 10

Stoichometric Coefficient ml m

2

0.40

0.20

Heat of Evolution (kcal/kg) k

48.0

375.0

Frequency Factor (1/hr)

3.6 x loj*

1.8 x 10

Activation Energy (kcal/mol)

39.5

37.5

3 Density (kg/m ) Po 380.0

364
Discussion of Presentations on Smoldering

Handa Presentation

Earl: Were studies on crystallinity index used? Did you see any changes in the crystal form? In other words, did you see a change

from cellulose 1 to cellulose 2?

Handa: Yes. However, without figures it is very distorted and hard

to understand.

Earl: But you see no cellulose 2.

Handa: We tried to get some but we failed.

Emmons: In Table 2, you had two values of various quantities. What

does 1 and 2 signify? Ml and M2, Ql and Q2 — what is 1 and 2?

Handa: Char 1 and Char 2.

Emmons: What is the difference between Char 1 and Char 2?

Ohlemiller: This is the thermal decomposition of cellulosic insulation

and it falls more or less into two stages of degradation. The first one is oxidative pyrolysis, and the second one is the char oxidation

process

Chaiken: Just a comment. Much faster heating and degradation of wood

is found using a laser. We are of the opinion now that the water that

is in the wood, as well as the water that is formed during the

composition, actually proceeds ahead of the thermal wave. At least

the charring wave plays a very important role in the progress of the

degradation.

We haven't looked in detail in terms of the precursor

oxidation reactions which might be subject to water. But from the

viewpoint of simply altering the thermal gradiants within the sample

as water is formed in the thermal wave, a water front is actually

moving ahead of the thermal wave, this supplies a good heat conduction

mechanism for heating wood entering the reaction zone. This would be

interesting from the viewpoint of your results which say that water

can possibly react in terms of some precursor reaction.

Emmons: You indicated that the oxygen uptake by various compounds

is related to the thermal expansion in various directions.

365
Handa: I mean oxygen uptake might be by lignin; it absorbs most

oxygen around 200°C when fission of the chain occurs thermally. Above

230°C, other processes suggested by Dr. Ohlemiller may occur.

Emmons: Does this imply that if the expansion is due to stress, there

is also an increase oxygen uptake.

Handa: Yes.

Friedman: I have a question on experimental detail. You state that

you measure the oxygen uptake by a decrease of pressure of the oxygen,

but if the wood is liberating gases at the same time, how does that

work?

Handa: We use several kinds of molecular sieve to analyze the gases.

366
FINAL SESSION REPORTS

367
REPORT OF TECHNICAL SESSION

ON PROGRESS REPORTS

F. Clarke, Chairman

The first technical session was devoted to progress reports on: fire

retardance, building design and smoke control, human behavior in fires,

and fire protection.

Dr. Saito reported on the use of fire retardant chemicals in Japan,

giving approximate amounts of use and numbers of manufacturers of

various kinds of fire retardants . A large amount of data was presented on smoke generation of urethane and polyvinylchloride , treated

with various additives and fire retardants. The relationship between

flashover and heat content of cellulosic materials was discussed, as was the flame profile as a function of location and size of pool fire.

For the American side, Dr. Clarke reported on several promising techniques

for the elucidation of molecular process in the pre-combustion and early

combustion phases. These include solid phase nuclear magnetic resonance

spectroscopy; a laser reduced particle ionization technique which is

effectively a time-of-f light mass spectrometer for incipient soot particles

and the opposed flow diffusion burner, useful for a variety of flame

phenomena

Dr. Morishita presented the Japanese progress report on Building Systems

and Smoke Control for himself and Dr. Wakamatsu. He reported briefly on several papers on building design, including advances in the field of

state transition modeling and network systems previously reported. Other

optimization techniques, and the contribution the components of fire

environment to the overall fire hazards, were reviewed as well. In the

smoke control field, Dr. Morishita described the new experimental test

facility in Tsukuba, which has been used for over 80 experiments so far

this year. He also reported on "cold smoke" studies in two large office

buildings in Tokyo. For one of the two buildings, the Shinjuku Center

Building, the smoke control system was found to perform effectively.

Measurement difficulties made performance of the other building systems

difficult to evaluate.

The American work on smoke control was presented at the "Annual Conference"

during the second week of the program. Dr. Klote of NBS reported on smoke

control modeling techniques for analysis of pressurized stairwells and on refinements of the ISI smoke movement model. The progress for developing

a smoke control manual was also reviewed. Smoke movement studies at

California Institute of Technology were reported by Dr. Zukowski.

Emphasis in this work is on room-to-room flow of smoke and hot gases in

the early stages of a fire. Other American work on building design is

closely related to human behavior, and was covered in the session on human behavior at the Annual Conference.

368
Dr. Jin reported on Human Behavior in Fires for the Japanese side.

He presented a proposed new exit symbol now under study in Japan. The

symbol may offer more legibility and clarity than a proposed ISO symbol.

Work on human vision through smoke was also extended over that reported

in earlier conferences.

Prof. Vreeland of the University of North Carolina reported at the

Annual Conference on the actions of occupants caught in a simulated

residential fire. Dr. Levin of the NBS discussed fire safety for the

handicapped and some of the implications which that carries for building

design.

Dr. Stahl of NBS and Prof. Francis of University of Florida, both discussed

the modeling of human behavior in fire situations. Dr. Stahl concentrated

on modeling the decision process which potential fire victims undertake,

while Francis concentrated on the description of people movement in

building evacuation.

Mr. Benjamin from the U.S. side discussed smoke detection status in the

United States. He estimated that as many as 50% of U.S. homes are now

covered by smoke detectors. Studies on the audibility of smoke alarms

were reported by Prof. Nober of the University of Massachusetts. He

reported that the 55db alarm level seems adequate as long as air con- ditioning and other interf erring noises are not present.

Prof. Miyama reported on Japanese work on smoke detection. He discussed

developments of criteria for performance of beam-type smoke detectors.

He also presented findings that visible light, when used in photoelectric smoke detectors, is attenuated substantially less than infrared

light under the same experimental conditions.

369
REPORT OF TECHNICAL SESSION ON

ARSON AND FIRE INVESTIGATION

I. Benjamin, Chairman

Mr. Karchmer presented a paper discussing some of the possible

reasons for an increase in arson in the United States. He then

went into detail on several of the early warning systems which

had been set-up to attempt to predict where arson will occur.

Mr. Kawamura gave some statistics on arson in Japan indicating

that it is not as serious a problem as in the United States, and

does not appear to be substantially growing. He also presented

some data from a supplemental report by Mr. Murakami which analyzed

in detail psychological and sociological aspects of arson that had

occurred in Japan.

A brief discussion was held on what might be the reason for

differences between growth of arson in the United States and

Japan. Several plausible explanations were suggested but no definite conclusions were reached.

370
REPORT OF TECHNICAL SESSION

TOXICITY OF COMBUSTION PRODUCTS

J. Bryan, Chairman

The session on Toxicity consisted of three segments with presentations

in the UJNR meeting on October 16, 1980. In addition, an informal

session was held on October 20. The final session relating to Toxicity was presented at the Annual Conference on Fire Research on October 23.

Dr. F. Saito, Building Research Institute, presented the paper entitled

"Basic Concepts on Toxic Hazards in Building Fire," written by

Kishitani and Saito. He emphasized that the burning condition of the

sample controlled the level of toxicity of combustion products.

Therefore, the detailed measurements of temperature and amount of air

supply to the sample in full size experiments are needed to define the

burning condition for the toxicity measurement. Also, he recommended

that the question of rapid acting toxicants should be included for the

evaluation of toxicity of combustion products.

Prof. Y. Nishimaru, Yokohama City University, reported on the study

of the toxic gas generated by the combustion of artifical turf. The

specimen samples were ignited in chamber test situations with eight

mice exposed in each test situation. The use of occupancies such as ball parks and golf courses for areas of refuge during earthquakes

motivated the concern for this study. The relationship between

amounts of COHb and C02~Hb in blood and incapacitation time of mice

was also reported.

Dr. M. Birky, Center for Fire Research, reported on the development

of the proposed modeling procedure for the determination of toxic

combustion products which was introduced to the Panel at the 1978

meeting. He reported on the seven laboratory evaluation projects,

involving twelve materials. Dr. Birky also presented the results

of the project to correlate the small test chamber results to a full

scale room situation for both a polyurethane and a cotton material.

The analytical comparison of the two situations was most significant

while the toxicological comparison indicated areas for further study.

The session on Toxicology during the Annual Conference on Fire Research was chaired by Dr. Birky. Dr. Barbara Levin, CFR, presented the data

on the seven laboratory evaluation study presented by Dr. Birky to the

Panel. Ms. Maya Paabo, CFR, presented the results of the small scale

to large scale test comparisons also previously presented by Dr. Birky.

371
Dr. S. Packham, a consultant, presented a review of the published

tenability time limits for CO and HCN from the Harvard School of

Public Health, National Academy of Sciences and National Bureau of

Standards. He emphasized that tenability limits vary with time and

the total time concentration curve must be considered in the evaluation

of materials.

Professor Y. Alarie, University of Pittsburgh, reported on their

studies to determine the time-concentration effects of toxic products

which involved large scale comparisons with the products of combustion

from the wall panels exposed in a room corner test. The study exposed

four groups of rats of four animals each, with varying smoke concentrations. Alarie agreed with Packham rather intently that the entire

time concentration curve must be utilized, and these curves are well

established.

Dr. Z. Annau, Johns Hopkins University, reported on the effects on rats

relative to the learned shock- avoidance responses when exposed to an injection of ethanol, ten minutes prior to a thirty minute exposure

to 1500 ppm of CO, with a thirty minute observed recovery period. His

data indicated significant changes in the responses produced and shocks

endured. He indicated his study did not evaluate the additional influence of thermal exposure which should be considered.

Dr. R. Meyers, Maryland Institute for Emergency Medical Services,

University of Maryland Hospital, Baltimore, reported on development

of a cognitive-perceptive clinical test procedure to evaluate the need

for the treatment of patients with suspect COHb levels, in the hospital

hyperbaric oxygen chamber. The results of the test use were presented

with the plans for improvement. Nurse Jones presented a Minico CO

analyzer which is being field tested as a diagnostic procedure to enable

EMT, CMT, and Paramedics to determine if a patient requires hyperbaric

oxygen chamber treatment. It was reported that FM radio transmissions

and alcohol breath both affect the instrument. The instrument is

currently being field tested on fire department personnel in the

Baltimore area.

Dr. G. Hartzell, Southwest Research Institute, reported on the study

supported by the U.S. Fire Administration, to determine the combustion

atmosphere in buildings encountered by fire department personnel. Ten

sampling boxes are being utilized by San Antonio, Texas, fire fighters

to collect samples for determination of levels of HCN, HCL, CO CO2, O2,

Benzine, Acrolein and Acetyaldehyde. The collection area consists

primarily of single family, frame dwellings. This is a followup study

from the Harvard University - Boston Fire Department study.

The discussions at all of these sessions appeared to be enlightening

and informative.

372
REPORT OF TECHNICAL SESSION

ADVANCES IN SPRINKLER TECHNOLOGY

T. Jin, Chairman

Presenting a paper, "Life Safety Factors Involved in the Use of

Sprinklers," Mr. O'Neill has reported on full-scale fire tests in

a patient room and mentioned as follows: "A dynamic heating

measurement of the sprinkler, in addition to the temperature rating

of the sprinkler, may be a primary design variable in future sprinkler

criteria. For life safety, a more rapidly responding sprinkler than

conventional sprinklers is necessary, but the benefit of it may not be

so significant for very rapid developing, shielded fires, such as fires

inside combustible clothing wardrobes."

Presenting a paper, "Sprinkler Technology and Design in Japan,"

Mr. Unoki reported on mandatory installation of sprinklers in Japan and

mentioned as follows: "The heads used in these systems are designed

to meet the standards which are characterized by the following: the

water distribution test is to be conducted using a single head, and

the relationship between the permanent and the elastic elongation of

the frame is to be defined. The proposal on time constant as the

requirement of heat response of heads is also being discussed."

Presenting a paper, "Advances in Residential Sprinklers," Dr. Kung

has reported on full-scale fire tests in a living room and mentioned

as follows: "Links considerably more sensitive than the commercial

link are essential in providing adequate protection in residential

fires. The required sprinkler operation conditions have been determined in terms of sprinkler water distribution associated with a link

five times more sensitive than the commercial link."

Through these reports, the sensitivity of link, the water distribution,

the smoke obscuration problem, etc. , have been discussed.

373
REPORT OF TECHNICAL SESSION

FIRE MODELING

T. Handa, Chairman

Prof. P. Pagni presented a report entitled, "Diffusion Flame Analyses

with Fire Safety Application." This was a clear review using classic

diffusion flow studies to assess the potential fire hazard of synthetic

polymers in fire. Flame heights produced by various materials were

shown to depend primarily on the mass consumption number, r, and

secondarily on the mass transfer number, B, when using an approximate

quasi-steady model for laminar diffusion flames. This emphasis on

the mass consumption number is new.

Mr. Y. Hasemi presented an excellent condensed review of the manuscripts

regarding recent advances in Japanese fire research including the

mathematical modeling of fire (Tanaka, Matsushima) , flashover as critical instatiblity (Takeda, Hasemi) , the extinction of infrared

radiation by smoke (Jin), the remote imaging of flames (Kawagoe)

statistical view on flashover occurrence (Morishita) , and criteria

on simulated model experiments (Saito)

Prof. Emmons presented a report entitled, "Computer Fire Codes," an overview of the current status of the Harvard Fire Code, which emphasized

the significance of numerical mathematical modeling in the practical

prediction of fire.

The presentation of a report entitled, "Recent United States Progress

in Mathematical Modeling of Fire Enclosure," was postponed to the

afternoon session. Dr. R. Friedman gave a comprehensive review of

the many computer programs in the United States which address components

of the compartment fire problem.

374
REPORT ON TECHNICAL SESSION

SMOLDERING

R. Friedman, Chairman

Dr. T. Ohlemiller of the National Bureau of Standards, Center for Fire

Research presented a survey paper entitled, "Modeling of Smoldering

Combustion Propagation." He divided smoldering into various regimes,

depending on low vs high permeability, and forward smoldering vs reverse smoldering (oxygen approaching from the burned vs the unburned

side of the reaction zone). He discussed the significance of ratios of

various characteristic lengths. He concluded that there is need for

more study of the smoldering problem, and especially on transition

to flaming combustion.

Prof. T. Handa of the Science University of Tokyo described work by

himself and his colleagues (S. Yoshizawa, M. Moria, M. Fukuoka, H.

Tsuhima, Y. Hashizume, and T. Nakamura), entitled, "Thermal Processes

in the Smoldering of Wood." Wood samples were heated in various

oxygen-containing environments. Measurements were made of weight loss,

oxygen consumption, X-ray diffraction, viscoelastic properties, thermal

analysis. In another series of tests, spheres of wood of various

diameters were exposed to heat over long periods, and conditions for

runaway thermal behavior were found. A collapse of the structure near 220°C was related to the kinetics of oxidations in the amorphous part

of the wood. The tendency to thermal runaway was shown to be dependent

on moisture content.

Following these papers, some general comments on modeling were made.

Prof. Emmons of Harvard University made a point with regard to studies

of flashover by making stability analyses of equations derived by

assuming that the fire may be represented by a series of steady states

at successive times. Quintiere, Thomas, and Hasemi have made such

analyses. Emmons commented that his numerical solutions of the full

set of time-dependent equations had not yet revealed any sudden

transitions as suggested by the stability analyses, and recommended

that an attempt be made to study more closely the relationship between

the two modes of analysis.

After the modeling discussion, Prof. Handa described some work on "Current-Voltage Characteristics of Pt Dispersed Sn02 Wafer," which

is relevant to detection of various fire gases, including carbon

monoxide, by a device which functions at room temperature.

375
RESOLUTIONS

376
RESOLUTIONS

The members of the UJNR Panel on Fire Research and Safety are very

happy with the results of the Fifth Joint Panel Meeting held in

Washington, D.C., October 15-24, 1980. The progress reports on the

many topics of concern to fire safety were very instructive. The

workshops on special topics held on Monday and Tuesday proved to be

especially valuable for all participants. The limited topics in

each of the simultaneous sessions together with the more informal

atmosphere lead to more intimate and detailed exchange of information

on the special topics.

The Panel Members herewith resolve:

1. That the next (6th) meeting of the UJNR Panel on Fire

Research and Safety be held in Tokyo, Japan, for five

working days in May 1982.

2. That the format of the meeting be as follows:

a) The first two days be devoted to progress reports on anaphases of fire safety: human behavior, fire modeling,

toxicity, sprinklers, detectors, fire and smoke retardants,

fire investigation techniques and building systems and

smoke control.

b) The next two and one-half days be devoted to workshops

on building systems and smoke control, human behavior, fire

modeling and toxicity with simultaneous sessions as appropriate.

c) The last one-half day of closing session contain session

reports, and adoption of resolutions.

3. That the meeting be held in several different laboratories

on different days, but that all sessions on any one day be

held all at one place.

4. That some cooperative fire research programs be started.

These will be especially valuable where the facilities are somewhat different in our two countries.

5. That the working personnel exchange be pursued more vigorously.

One NBS employee, Dr. Mulholland, spent a valuable month in

Japan. The U.S. is looking forward to the visit of Dr. Tanaka

for a year beginning in the near future. It is hoped that

someone from the U.S. can be sent to Japan for an extended

period of research in the not so distant future.

377
6. That the toxicity tests by mice (Japan) and rats (U.S.) be

correlated by the testing by each country by their respective

methods of common samples. This would perhaps be best done

by each country submitting to the other for tests, samples

of materials already tested in the home country.

7. That Panel Members be encouraged to exchange information of

interest through the respective Chairmen between meetings.

A few such exchanges occured during the past year, but

there should have been many more. Reports should be submitted

in the original language with an abstract in the other

language.

8. That to improve communication during meetings, especially

the first two days of formal progress reports, copies of all

the relevant reports be sent in time to be received in the

other country by one month ahead of the meeting.

378
Bibliography Of Support Papers*

Fifth UJNR Panel on Fire Research

ARSON & FIRE INVESTIGATION

Murakami, Y. , Uehara, K. and Takahashi, T. Incendiary Fires in Tokyo;

Tokyo Fire Department.

Yamoka, K. Features of Patterns in Arson - 1. A Comparison Between

the Single Offense Group and the Serial Offenses Group; Nat'l Research

Institute of Police Science.

White Book on Fire Service in Japan; Fire Defense Agency, Japan, 1976.

TOXICITY OF COMBUSTION PRODUCTS

Kishitani, K. , Saito, F and Yusa, S. Basic Concept of Toxic Hazards

in Building Fires.

DETECTION

Handa, T. , Fukaya, H. , Muruyama, T. , Hoshino, K. , Endo, K. and

Okayama, Y. Pt and Sb Profiles in the Sintered Sn02-Pt-Sb203 System

and Their Effect on I-V Characteristics; Proceedings of 22 Japan

Congress on Materials Research, The Society of Materials Science,

Japan, 1979, pp. 326-330.

Handa, T. , Fukaya, H. , Muruyama, T. , Hoshino, K. , Endo, K. and

Okayama, Y. The Current-Voltage Characteristics of Pt-Sn02 PointContact; Proceedings of 22 Japan Congress on Materials Research, The

Society of Materials in Science, Japan, 1979, pp. 220-224.

Handa, T. , Fukaya, H. , Sugawa, 0., Kaneko , K. , Hameda, T. , Furukawa, Y.

and Endo, K. Performance Characteristics of Detector to Fire Products

through Corridor and Compartment; Bulletin of Japanese Assoc. of Fire

Science and Engineering, Vol. 28, No. 2, 1978, pp. 11-18.

FIRE MODELING

Handa, T. , Hamada, T. , Sugawa, 0., Fukaya, H. and Endo, K. Experimental

Study on the Branching of Flow through T- Shaped Corridor; Bulletin of

Japanese Assoc. of Fire Science and Engineering, Vol. 27, No. 1, 1977.

Handa, T. and Sugawa, 0. Flow Behavior of Plume from Growing Fire

Source in High Ceiling Enclosure; Science Univ. of Tokyo.

* Unpublished papers, prepared for 5th UJNR Conference, are available

through the Fire Research Information Services, Center for Fire Research,

National Bureau of Standards, Washington, D.C. 20234 (USA).

379
Handa, T. , Sugawa, 0. and Watanabe, A. Motion of Fire Products in High

Ceiling Enclosure; CIB Symposium, 1979, pp 111-29 - 43.

Hasemi, Y. Mathematical Study of Flashover, BRI, Japan.

Jin, T. and Kumano, Y. On Extinction of Thermal Radiation Through

Fire Smoke; Fire Research Institute, Tokyo, Bulletin of Japanese Assoc.

of Fire Science and Engineering, Vol. 28, No. 1, 1978.

Kawagoe, K. , Mizuno, T. , Maruyasu, T., Uchiyama, H. and Hasemi, Y.

A New Method to Measure the Geometrical Aspects of Flame, Japan.

Matsushima, 0. A Numerical Study of the Smoke Layer Forming Process

in a Compartment Fire, NTT, Japan.

Saito, K. and Emori, I. Theoretical Prediction for the Applicable

Range of Scaling Laws on Tank Fire Model Experiments.

Tanaka, T. A Model on Fire Spread in Small Scale Buildings; 2nd

Report, BRI Research Paper No. 84, March 1980.

Yumoto, T. , Takahashi, A. and Handa, T. Combustion Behavior of Liquid

Fuel in a Small Vessel: Effect of Convective Motion in the Liquid

on Burning Rate of Hexane in the Early Stage of Combustion; Combustion

and Flame, The Combustion Institute, 1977, 30, 33-43.

SMOLDERING

Handa, T., Yoshizawa, S., Suzuki, M. and Fukuoka, M. Mechanical

Performance of Lignin and Cellulose in the Dynamic Viscoelasticity

of Wood at High Temperature Region; Proceedings of 22nd Japan Congress

on Materials Research, The Society of Materials Science, Kyoto, 1979

pp. 223-228.

Handa, T., Yoshizawa, S., Fukuoka, M. and Suzuki, M. Dynamic Viscoelasticity of Wood-Polymer Composites Prepared by an Electron Beam

Acceleator, Science Univ. of Tokyo, Plenum Pub. Corp. 1980, pp. 263-276.

SMOKE CHARACTERIZATION

Handa, T. , Suda, K., Kato, Y., Yamamura, T. , Ishii, T. and Shintani, A.

An Improved (0.06-10.0 ym) Optical Counter and Monitoring Particulates

from Combustions; J. Disperson Science and Tech., 1(2), 1980, pp. 209-231.

Suda, K. and Handa, T. Portable Optical Particle (0.06 umm) Counter,

Rev. Sci. Instrum., American Inst, of Physics, Vol 50, No. 7, Jul. 1979,

p. 831.

380
FLAME RETARDANCE

Handa, T. , Nagashima, T. and Ebihara, N. Synergistic Action of

SD2O3 with Bromine-containing Flame Retardant in Polyolefins, 1-The

Variance in their Performance Versus Sb/Br Ratio; Fire and Materials,

Vol. 3, No. 2, 1979, pp. 61-67.

Handa, T. , Nagashima, T., Takahashi, Y., Suda, K. , Ebihara, N. and

Saito, F. Characterization of Smokes from Flame-Retarded Plastics on

the Basis of the Size Distribution of Particles, Fire Research, 1,

Japan, 1977/78, pp. 265-272.

Handa, T. , Nagashima, T. , Takahashi, Y., Tsushima, H., Yamamoto, H.

and Ebihara, N. Synergistic Effect of THPC and M^Br on the Flame

and Smoke Retardancy of Phenol-WPC; Vol. 25, 1979, pp 600-609.

Handa, T., Nagashima, T. , Yamamoto, H. , Tsushima, H., Miyanishi, S.

and Ebihara, N. Effect of Oxygen Partial Pressure on the Combustion

of Organic Materials in the Hot Wire Ignition Test; Proceedings of 23

Japan Congress on Mat'l Research, Society of Materials Science, Kyoto,

1980, pp. 327-332.

Handa, T. 1, Yoshizawa, S., Nagashima, T., Tsushima, H., Yamamoto, H.

and Ebihara, N. Effect of the Mechanical Structure on the Combustion

Behavior in the Phenol-Fire Retardants-WPC; ibid. pp. 333-337.

Handa, T. , Nagashima, T. , Takeda, H. , Ebihara, N. and Takahashi, A.

Oxygen Index and Other Parameters for the Evaluation on the Effect of

Fire-Retardants ; Proceedings of 76 Int'l. Symposium on Flammability

and Fire Retardants, Fire Retardants: 1976, pp. 45-54.

Handa, T., Nagashima, T., Takahashi, Y. and Ebihara, N. Augmented

Cooperativity Between Halogen and Phosphorus in the Fire-RetardantPhenol-Wood, Proceedings of 22 Japan Conference on Materials Research,

Society of Materials Science, Kyoto, 1978, pp 306-312.

Handa, T., Nagashima, T. and Ebihara, N. The Synergistic Behavior

of Antimony Trioxide in Endorsing the Performance of the Halogen

Containing Fire-Retardants in Polyolefins, Proceedings of 21 Japan

Conf . on Mat' Is Research, Society of Materials Science, Kyoto, 1978,

pp. 326-331.

SMOKE CONTROL

Kaneko, K. , Handa, T., Suda, K. and Suzuki, H. Change of Smoke

Particles Size and Elimination of Smoke by Corona; CIB Symposium, 1979,

pp. 111-45 - 57.

Smoke Control Design for Shinjuku Normura Bldg. ; Yasui Architects,

CIB W14/80/43(J) Japan.

381
HUMAN BEHAVIOR

Kasaigakkai, N. Evaluation of Fire Safety in Buildings; Occasional

Report of Japanese Association of Fire Sdxence and Engineering, No. 3

1979.

Takeda, H. , Kawaguchi, T. and Akita, K. Critical Phenomenon and

Unstable Behaviour in Compartment Fires; Univ. of Tokyo.

382
NBS-114A (rev. 2-eo) U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBS SP 639

2. Performing Organ. Report No. 3. Publication Date September 1982

4. TITLE AND SUBTITLE

FIRE RESEARCH AND SAFETY - Proceedings of the Fifth Joint Panel Meeting of the U.S.-

Japan Cooperative Program in Natural Resources held October 15-24, 1980, at the

National Bureau of Standards, Gaithersburg, MD.

5. AUTHOR(S)

Joyce E. Chidester, Editor

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions)

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C 20234

7. Contract/Grant No.

8. Type of Report & Period Covered

Final

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

Same

10. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Number: 82-600580

I | Document describes a computer program; SF-185, FlPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

The Fifth Joint Panel Meeting of the United States - Japan Panel on Natural Resources (UJNR), Fire

Research and Safety, was held at the National Bureau of Standards in Gaithersburg, MD, from October

15 through 24, 1980. The meeting consisted of in-depth technical sessions on arson and fire investigation, toxicity of combustion products, advances in sprinkler technology, and fire modeling.

Progress reports briefly covered fire retardance, building design, smoke control, human behaviors

in fires, and fire protection. Two days of informal sessions were held on toxicity, human behavior,

detection and smoke properties, sprinklers, smoldering, and fire modeling. This meeting was held in

conjunction with the Center for Fire Research's Annual Conference which included United States presentations of related technical subjects. The proceedings include the technical papers presented at the UJNR meeting along with the ensuing discussion and the summary reports prepared by each session

chai rperson.

The first meeting of the UJNR Panel on Fire Research and Safety was held in Washington, DC,from

April 7-8, 1976, where the current activities in the United States and Japan on fire research and

safety were introduced. After this exchange, the following six topics were selected for initial

cooperation: toxicity, building systems, human behavior, smoke control, detection and smoke

properties, and modeling of fire.

The participants resolved that the sixth meeting, to be held in Tokyo, would cover the following

topics in-depth: (1) building systems and smoke control, (2) human behavior, (3) fire modeling,

and (4) toxicity. Progress reports will be submitted in the areas of human behavior, fire

modeling, toxicity, sprinklers, detectors, fire and smoke retardants, fire investigation

techniques, and building systems and smoke control.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

arson; building design; combustion products-, fire investigation; fire modeling;

fire protection; human behavior; smoke control; smoldering; sprinkler systems;

toxici ty . 13. AVAILABILITY

Unlimited

| | For Official Distribution. Do Not Release to NTIS

[X] Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D C

20402.

Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

394

15. Price

$9.50

USCOMM-DC 6043-P80

^U.S. GOVERNMENT PRINTING OFFICE! 1 9 8 2 - 3 6 O " 9 9 7 / 2 2 0

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