NBS

PUBLICATIONS

NBSIR 86-3360

A111DE bSSSlfi

NATL INST OF STANDARDS & TECH R.I.C.

All 10265551

/Workshop on Fire Protection Technology QC100 .U56 NO.86-3360 VI 986 C.2 NBS-PUB- p on

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Fire Protection

A Record of the U.S. Papers Prepared tor the Workshop on

Fire Protection Technology

Compiled by:

Kurt F. J. Heinrich, Chief, Office of International Relations

Andrew J. Foweil, Chief. Fire Safety Technology Division

' Doris M. Bluebond. Program Analyst, Office of International Relations

April 1986

QC

100

.U56

#86-3360

1986

c.2

\RTMENT OF COMMERCE

UREAU OF STANDARDS

NBS

RESEARCH

INFORMATION CENTER NBSIR 86-3360

WORKSHOP ON FIRE PROTECTION

TECHNOLOGY

(A Record of the U.S. Papers Prepared for the Workshop on Fire Protection

Technology held in Cairo, Egypt, April 27-28, 1986)

U.S. Papers:

Kurt F. J. Heinrich, Chief, Office of International Relations (NBS)

Irwin A. Benjamin, Benjamin/Clarke Associates, Inc. Richard W. Bukowski, Head, Hazard Analysis, Center for Fire Research (NBS)

Richard L P. Custer, Associate Professor and Associate Director,

Center for Fire Safety Studies, Worcester Polytechnic Institute

Andrew J. Fowell, Chief, Safety Technology Division, Center for Fire

Research (NBS)

April 1986

The workshop was conducted as part of the program under the U.S. /NBS

Agency for International Development, PASA EGY-0016, Applied Science

and Technology Research Project 263-0016.

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

NATIONAL BUREAU OF STANDARDS. Ernest Ambler, Director
N
FOREWORD

Within the framework of the Applied Science and Technology Research

Program between the Governments of Egypt and of the United States of America,

the National Bureau of Standards (NBS) is executing a program of assistance

to Egyptian Standards Organizations* The NBS program is financed under a Participating Agency Service Agreement (PASA) between the United States

Agency for International Development (AID) and the National Bureau of Standards.

The Egyptian organizations involved are the Egyptian National Institute for

Standards (NIS), under the Egyptian Academy of Scientific Research and

Technology, and the Egyptian Organization for Standardization and Quality

Control (EOS), which is a dependency of the Ministry of Industry of the

Egyptian Government. Through NIS, NBS also interacts with the Assay and

Weights Administration, which is under the Weights and Measures Service of

the Ministry of Supply and Trade.

The aim of this program is to strengthen systems of measurement,

calibration, standards and quality control in Egypt and to promote the

research in metrology on which these activies are based. But to translate

the progress being achieved in the Egyptian institutions into changes

beneficial to the economy and productiveness of Egypt, we must ensure

that the services of these institutions are fully known, recognized and

utilized by the industries.

To promote such interaction NBS assisted the National Institute for

Standards, in organizing a workshop entitled "Fire Protection Technology"

which was held at the Meridien Hotel, Cairo, April 27-28, 1986. The

contributions prepared by the U.S. speakers are reproduced here. We hope

that this workshop and publication achieved their aim to make our viewpoints

on the value of fire safety known to the intended audience.

i
>
TABLE OF CONTENTS

Page

I. Papers

A. Kurt F. J. Heinrich

"The National Bureau of Standards and Its International

Programs'* . . . I

B. Irwin A. Benjamin

"Fire Tests in the United States" 5 "Fire Safety Codes in the United States” 13

C. Richard W. Bukowski

"Engineering Applications for Fire Related Prediction Tools” 19

"Fire Detection and Alarm Systems" 25

D. Richard L. P. Custer

"Fire Statistics and Their use in Fire Protection" 39

"Failure Analysis and Analytical Fire Investigation"............. 47

E. Andrew J. Fowell

"Fire Organization in the United States" 57

"Industrial Fire Suppression”... 63

ii

The National Bureau of Standards and Its International Programs

Kurt F. J. Heinrich

Chief, Office of International Relations

National Bureau of Standards

Gaithersburg, MD

Industrial development and growth, and the advancement of the quality of

life, are impossible in this industrial era without an adequate measurement

capability and without an organization which puts this capability at the

service of the nation. Without measurement skills, it is impossible to

control the quality of industrial production, the economy of production

processes, and the fabrication of the innumerable devices and products

that interact with other devices and products. As international commerce

becomes more vital for the internal economy of each country, the establish"

ment of international standards linking the measurement networks of all

nations becomes equally important.

An industrializing nation must also pay attention to the hazards of daily

life, and establish norms and regulations which minimize the effects of

fires, earthquakes, collapses of buildings, toxic effects of impurities

in air, water, foodstuff and medications. All these safeguards are impossible to establish without adequate measurement capabilities.

The necessity for standardizing the devices used to provide safety to the

public was brought to light painfully in an episode which is germane to this

workshop. In 1904 a fire broke out in the city of Baltimore. It propagated

quickly through the buildings and streets, until a large part of the city

was involved; the disaster went on for several days. Firefighters arrived

at the scene from cities as far as Washington and New York. When they

prepared to connect their hoses to the fire hydrants, they discovered

that this could not be done because the dimensions of the connectors varied

from city to city. As a consequence, the firemen from out of town could not

provide effective help to the local forces, and much of Baltimore was destroyed in the disaster.

To assist their industries with measurement problems, and to safeguard

against the occurrence of incidences such as I have just described, all

countries create institutions which provide a national focus of metrology,

and coordinate their measurement units with those of other countries. In

Egypt, the primary responsibility for this task is given to the National

Institute for Standards (NIS), which is the Egyptian sponsor of this

workshop; in the United States of America, the corresponding institution

is the National Bureau of Standards (NBS).

1
NBS was created in 1901, only three years before the Baltimore conflagration,

by the Congress of the United States. At that time, the American industry

was developing rapidly, and the need for this measurement center was keenly

perceived by industry and science. The structure and functions of NBS

arise from historical necessities, and there are not two corresponding

institutions in the world which have exactly the same characteristics. For

instance, NBS, unlike similar institutions in many other countries, is not

involved in law-enforcing processes, and only to a very small extent in

the writing of engineering standards. Its dominant concern is measurement,

and to understand measurement in all spheres of technology requires the

study of the physical and chemical sciences which describe the measurement

processes as well as the characteristics of the things to be measured.

In this process, NBS quickly became an important resource to other government

agencies which needed its services in diverse technological problems.

The present structure of NBS can be seen in Table 1.

Besides the scientific studies mentioned above, NBS provides services of

measurement and calibration, distributes standard reference data referring

to various physical sciences, and distributes at cost standard reference

materials which can be used for secondary calibration in science, medicine,

industry and commerce.

NBS is the custodian for the United States of the primary standards for

quantities such as length, mass, time and frequency, electrical and thermometrical units. The coordination of these standards with the international

standards, through the International Bureau of Weights and Measures, is one

of the international activities of the institution. NBS also represents

the United States of America in other International bodies such as the

International Organization of Legal Metrology, and in the discussions of

the Economic Commission for Europe.

The provision of calibration services and standard reference data, and

the distribution of standard reference materials is another facet of

international cooperation. NBS also hosts scientists from all over the

world to work as guest3 in our laboratories, and at present we have approximately 165 foreign scientists working with ours for periods which vary

typically from 6 to 24 months.

We also cooperate in special programs with many nations, either under

direct agreements between a foreign institute with NBS or within the framework of agreements between nations. Such cooperation tends to strengthen

the technical capabilities of both participating institutions, as well as give us a mutual opportunity to know better our colleagues in other

countries. The present workshop on fire protection technology is part of

the cooperation of NIS and NBS within the framework of the Applied Science

and Technology Research Project, executed by the Egyptian Academy of

Scientific Research and Technology, and the U.S. Agency for International

Development. I hope that it will contribute to strengthen the friendship

between our two nations, and to help you to improve fire prevention

measures in the Arab Republic of Egypt.

2
U.8.

DEPARTMENT

OF

COMMERCE

National

Bureau

of

Standards

pH

Es3 m

<

3

JULY

22.

1985
4
FIRE TESTS IN THE UNITED STATES

Irwin A. Benjamin

Benjamin /Clarke Associates, Inc.

Kensington, Maryland

1 . Introduction

This paper will talk about the use of fire tests in the

United States; and their relationship to the codes and

standards. Generally, most tests have been developed to

answer a regulatory need and are either directly referenced

in the codes or used as part of the product acceptance

criteria in the code system. The tests can be categorized

as follows:

o flame spread

o fire resistance

o non-com bu s t i b i 1 i t y and heat release

o f urnishings

o electrical

o mechanical

2. Flame Spread

The ASTM E84 test is one of the most widelv used fire

test. This test evaluates the rate of flame spread that

will occur in a fire under a forced draft. It attempts to

simulate the drafts that would occur along the surface of a wall or ceiling lining by using an air draft of 73 m/min.

a
through the test chamber. The test is conducted in a

chamber that is 7600 mm long and 450 x 305 mm cross

section. A burner at one end is supplied with gas at a

rate of 5.3 MJ/min. The rate of travel of the flame spread

along the specimen, which is on the top of the chamber, is

then measured. The time-distance relationship is converted

into a set of flame-spread classifications. These

classifications are used to regulate wall and ceiling

lining materials both within rooms and in corridors, stairways and exits. Although the test has also been used

to measure smoke development, its use in the regulations is

for flame spread classification.

The E648 test is used to evaluate floor covering systems. This

test uses .a radiant panel which is inclined at a 30° angle with

a horizontal specimen. The specimen forms the bottom of the

test assembly, and is mounted similar to the way it would be on

the floor in a room. For instance, if the specimen is a carpet,

and is to be installed over a resilient pad, it would be so mounted

for the test. The radiator imposes a varying flux from 11 to 1

kW/sq. m. along the length of the test specimen. The distance

which the fire travels along the specimen is used to measure the

susceptibility of the flooring material to the spread of flame.

This distance is translated into a critical radiant flux - the

minimum flux from the panel needed to sustain flame spread. The

regulatory codes have used this critical flux for

regulating carpeting in both rooms and corridors. A

similar test is E970 which is used to evaluate attic

6
insulation in buildings. This test uses the same equipment

as the E648 test and measures the critical radiant ilux for

insulation used in ceilings. Its use is mandated in

federal, regulations by CPSC (Consumer Product Safety

Commission) for governing the flammability of insulation in

res idences

Another flame spread test is the UL901 test for cables.

This test is an adaptation of the E 8 4 test. The test

cables are in a tray suspended from the ceiling of the

furnace. This test has been used to evaluate whether

electrical cables can be classified as low flame spread and

are therefore allowable for use in air plenums.

Fire Resistance Testing

The A STM El 19 test is the oldest A STM fire test. It

originally dates back to about the early 1900's; and it is

used to evaluate beams, columns, wall., floor and ceiling

constructions. Comparable fire tests, E152 and EL63, are

used for doors, and windows. More recently test E814 has

been adopted for the evaluation of penetrations in walls

and floors. These tests all follow the same time exposure

curve which Is comparable, but not Identical , to the ISO

fire resistance curve. The test appears in all the

building codes and the fire resistance is generally

7
specified as 1, 2 or 3 hour fire resistive requirements.

The fire resistance specified depends upon the size of

building, height, and its occupancy. The E l 1 9 test has

detailed information about moisture levels at testing and

moisture corrections, since this factor has been found to

be important in fire test results. Also information on

estimating the degree of restraint to be applied to beam

ratings is needed, since beam fire resistance ratings will

vary with the design restraint. There are multiple

publications in the U.S. that list the many types of

constructions that have been tested for fire resistance;

and these test results are incorporated in the building

codes .

The fire resistance of roofing is controlled by the E108

test method, which includes a series of tests: intermittent flame

exposure, spread of flame, burning brand, flying brand, and

rain test. Various sizes of burning wood brands are placed

on the test roof, depending upon the classification

desired. The test specimen is 1000 mm wide by 1300 mm long

for all tests except the flame test, which requires a 1000

x 4000 mm sample. This test is used to control roofing

fire resistance, depending on the type of building and the

occupancy .

Non-Combustibility and Heat Release
Most of the codes require non-combustible components i. n the

construction of the more fire resistive buildings. The

non-combustibility test that is referenced in the codes is

ASTM E136. This test uses a refractory tube, 76 mm

diameter and 210 mm long, which is heated to 7 5 0

0 C . A sample is plunged inside the ceramic cone and measurements

are taken of the temperature rise and weight loss; and

observations are made on the presence of flaming. The NI'PA

test # 2 59 for potential heat .of building materials is

referenced in some of the NFPA (National Fire Protection

Association) fire standards. This test measures the amount

of heat that would be contributed when a material is

exposed to a 750°C fire. This test is used to define

materials of "limited combustibility".

The ASTM E906 test measures the rate of heat release of

materials. In this test, materials are subject to a radiant fLux at different specified levels from 10 to 50

kW/sq.m. and the rate of heat release is measured. This

test is not currently used in building codes. However, it

has been specified for use by the FA A (Federal Aviation

Administration) for materials in airplane interiors.

Furniture and Furnishings

9
Curtains and draperies are regulated by NFPA 701. This

test consists of two parts: a small scale and a large

scale test. Normally both of these tests are employed on any decorations in a building, including curtains and

drapes. In the small scale test a 70 x 250 mm specimen Ls

mounted vertically and subject to a small burner. The

Length of char is measured and Its maximum value is

specified. In the large test four samples of 127 x 2130 mm

are hung vertically to form 4 folds. The specimens are

also subject to a small burner and the length of char Ls

determined

NFPA 260A and 260B specifies tests to measure the i. gnition

resistance of furniture. There are 2 tests, one to

evaluate the components of the furniture and the other to

evaluate an assembly of the components. In general the

component test is used to regulate furniture inside rooms,

whereas the assembly test is used for furniture in public

spaces.

6. Mechanical Tests

There are multiple tests that are used to approve equipment

for heating, ventilating, and air conditioning systems.

For example, UL.Lftl is a product standard for duels used tor

moving air. This standard combines several different i ir

10
test method s

From these tests ducts are classified . The

building codes refer to this standard for duct classification. Similarly there are product standards for

various types of furnaces, heating units and chimneys.

Listing or approval under these standards 1 s required by

building code officials; and they are referenced in the

regulatory codes as " listed appliances".

Electrical Tests

The building codes require materials or electrical

installations which conform to NEC (National Electrical

Code, NFPA 70). This code relies heavily on the II L*

listings of materials. These listings in turn include

multiple fire tests. A common example is UL94 which is the

standard test for flammability of plastic materials that

are used in appliances. This test uses a sample 13 mm wide

by 127 mm long. The specimen can be oriented either

horizontal or vertical and is tested by exposing It to a

small, burner at one end. There are muLtlpLe

classifications that are derived from the Lest. AIL

for either overheating or fire potential by various types

of tests that are generic t o the particular electrical

equipment.

* Underwriters Laboratory

appliances and material components are evaluated

11
8 . S ti m - a r y

In general, we have reviewed some of the fire tests

are common!1. y use d i n t' h e regalI at ory field in the U n States and given a very brief i d ea o f the nature o f

test.

w h i c h

t ed

each

12
FIRE SAFETY CODES IN THE UNITED STATES

Irwin A. Benjamin

Benjamin/Clarke Associates, Inc.

Kensington, Maryland

1 n t rod iic t: Lon

There are different types of safety codes in the United States.

They primarily come under the categories of construction

,

installation, or maintenance codes. Construction codes are

applicable when the building Is constructed and govern the

design of the building and the use of materials in the

building. Building codes may be divided into architectural,

mechanical, and plumbing requirements.

The installation codes govern the procedures for the safe

installation of certain key equipment. For example , the

National Electrical Code covers the installation of electrical

wiring. We also have a sprinkler code, a standpipe code, and a detector code. There are in addition multiple other codes for

the installation of specialized equipment such as industrial

ovens, kitchen equipment, and so forth. The National Fire

Protection Association publishes over two hundred codes in this

c a t e g o r v .

Finally, there are the maintenance codes which are normally

called "fire codes". These codes deal with the operation of the

building and limit the uses of the building, storage of

hazardous materials, and maintenance of the systems that are

required for life safety within the building.

13
All the codes within the United Slates derive their legal

a n L h o r i t y from the fifty states. There are no federal codes,

nor does the federal government have jurisdiction. The states

may promulgate their own codes, use nationally recognized

standard codes, or delegate their authority to the cities and

towns to develop and enforce their own codes. In general,

regardless of who promulgates or enforces the codes, the legal

authority is based on the right of the state to provide

regulations for the safety and welfare of its inhabitants. The

typical building code in the United States has about three

quarters of its contents dealing with fire safety and the other

one quarter dealing with structural design.

The concept of the building codes has been based on the ability

of the people to evacuate a building safely. The early codes in

the beginning of the Twentieth Century were designed primarily

to prevent conflagrations between buildings. The code features

were then revised to prevent burnout within a building; and

currently, the codes are designed to provide for safety on a single floor of a building. Essentially, the codes are designed

to prevent multiple deaths, but not necessarily to prevent an

individual death from occurring.

14
II. Building Codes

The codes generally si art out: with a descript ion of the tvpe of

occupancy. All buildings are divided according to the type of

the people and the usage of the building: generally, i. nto about

ten divisions with some subdivisions. The requirements for the

buildings vary according to the occupancy use since this

reflects different degrees of hazard, and therefore the need for

different levels of fire safety. tn addition, buildings are

divided bv the type of construction. In general, they are

c.atagorized into combustible or non combustible types, as a function of the amount of fire protection that they have

received. The occupancy and type of construction determine the

height and area of the building that is allowed. T fra t is, the

number of stories in the building and the number of square

meters per floor are determined from the hazard associated with

the occupancy and the type of construction of the building. The

codes also have provisions for special types of buildings such

a s high-rise buildings, parking structures, covered m a L 1 s and

atriums.

A large part of most building codes deal with the egress

system. Considerable attention is paid to the adequate size of

evacuation routes, the number of routes, the size of the doors,

the control of smoke movement within the building, and the

construction of the escape routes.

15
There are requirements for materials that are used in I lie buildings. These are particularly applicable to the linings or

interior finishes of the walls, ceilings, and floors of the

building. The requirements are more restrictive in the escape

routes than they are in Lite rest of the building, but all are

covered

Other requirements cover such things as mechanical equipment

systems, furnaces, ovens, chimneys, and stacks; and there are

requirements for the fire resistance of various types of doors,

floors, walls, windows, and the treatment of openings within

these fire resistive barriers.

The plumbing code section of the code is designed to govern the

requirements for potable water supply and sanitation in

buildings. It is the most prescriptive section of the code, and

it covers such things as the materials to be used in the water

supply system, the amount of water that should be supplied per

individual person, and methods of installation.

III. Installation Codes

These cover a tremendous amount of different types of equipment

from very specialized types, such as industrial ovens, to basic

16
building rt'(| n i rcmcnt s , such ;is sprinkler end standpipe systems.

A tvpicel example Is 1 he Nel: i on a 1 Electrical Code. This code is

designed to provide I Or the sefc i n s l e 1 l a L i o n of electrical

systems in e building, protecting against: electrical shock or

possibility of fire. The code covers the design of the wiring

s vst e in , the a I. L o w a b J. e materials that can be used and their

limitations, specifications of various types of equipment such

as lighting fixtures, electrical, heaters, electric motors,

air-conditioning equipment, and how they should be installed.

IV. Maintenance Codes ©

Whereas the previously mentioned codes were all enforced by the

building inspectors during the time of construction, maintenance

codes relate to the operation of the building and are enforced

periodically by the Fire Brigade. One such code is called the

Fire Code. This code has provisions for the maintenance of fire

protection and life safety systems in a building, such as the

sprinklers, detectors, and standpipe systems, and for

maintaining the integrity of the fire resistive wails and

partitions. There are fire safety provisions governing

incinerators, the storage and use of flammable material, and

uses of the building itself. The code also covers the

maintenance of the exitway s to make sure that the Interior

finishes are not degraded and the exit ways are not obstructed.

17
Il has a seel ion which covers m;i i nt en.uu.o of s;i f c condit ions

d u r i n g I li c [ h c «i I l oral i. on or mod i f i c a t i o n o f a h u i I d i. n g .

V’ . Model Codes

There are four model codes in the United States: the Uniform

Building Code, the Southern Building Code, the National Building

Code, and the Life Safety Code. The first three are complete

codes: they cover all features of the codes - structural, fire,

mechanical, and plumbing. The Life Safety Code is strictly

devoted to fire safety for individuals. The codes are adopted

by the various states and localities so that most of the codes

in the country that are enforced are one of the model codes.

18
Engineering Applications for Fire Related Prediction Tools

Richard W. Bukowski , P.E. Head

Hazard Analysis

Center for Fire Research

1 . Int ro duct ion

Traditionally, the practice of fire protection engineering has

involved the application of expert judgement and experience to

current problems. This is largely accomplished through the

development and use of prescriptive codes, standards, and manuals

of practice through a consensus process, by committees made up of

such experts. While this system has served us reasonably well in

the past, it is not without its weaknesses.

These committees, and the codes which they develop, tend to deal

well with traditional problems since they are founded in

traditional experience, both with actual fires and with fire

tests. More recently, however, technology and materials science

have b e qji changing rapidly such that more and more decisions must

be made by these committees and by enforcing authorities in the

absence of any experience or historical precedent upon which to

make such decisions. This situation generally leads to extreme

conservatism and redundance leading to increased cost, at least

until experience is gained with the new technique or material.

A potential solution to this problem rests in the development of

predictive methods which* will allow performance based codes by

providing a practical mechanism for evaluating the impact of new

technology or materials without the necessity for conducting

extensive, and prohibitively costly full-scale experimental

analys es

The purpose of this paper is to provide an overview of some of

the predictive methods which are currently available to

practicing engineers.

2. Predictive Methods

The current fire-related prediction tools have been developed as

a direct result of fire research conducted around the world and

the availability of low cost, high performance computers. In

general, the ability to predict a given fire phenomenon begins

with well-designed experiments. Analysis of the data from these

experiments produces an empirical understanding of the

interrelationship of important variables.

Through the application of the principles of physics, chemistry,

fluid mechanics, etc., the process of interest can be described

completely in terms of basic properties and physical constants.

This represents a phenomenological understanding of the process

and a mathematically self-consistent description of it.

19
The form of the cur rent ly-available predictive tools covers a range from simple, algebraic equations through highly complex

computer models involving ordinary or partial differential

equations. At the simplest end, algebraic equations (generally

s emi -emp i r i c al ) have been derived for many processes and are

suitable for estimation purposes since they generally deal with

steady-state phenomena. Since fire is a highly dynamic process,

these steady-state solutions represent inexact but useful

techniques for engineering purposes.

Since the presence or absence of safety to a structure or its

occupants is highly time-dependent, times to events are of

fundamental importance. But the time dependent form of the

equations governing a fire related process is generally too

complex for hand-calculated solutions. Therefore, fire models

have been developed which use the computer to solve these time

dependent equations.

Most such computer fire models solve sets of ordinary

differential equations as a q uas i -s t e ady -s t a t e approximation.

That is, the transient solution results from a series of short

time intervals over which the process is considered to be steadystate. If the selected time intervals are short enough, (of the

order of fractions of a second) the assumption of a steady-state

process over this short time interval is a good one.

In order to provide a full transient type analysis, one needs to

solve a* set of partial differential, equations for the process of

interest. While this is done in some models, it is usually not

practical for engineering purposes since the time required for

solution, and the computer necessary to solve all of the partial

differential equations for even a simple case is impractical for

most engineering-related problems. These models do serve a very

useful purpose within the research community, however, in that

they provide insight int$ the most basic levels of the physics

and chemistry of the process.

3. Algebraic Equations

As stated earlier, a number of algebraic equations suitable for

hand calculation have been developed for some specific firerelated processes. Many of these equations have been compiled in

a report by Lawson and Quintiere [1], along with a detailed

discussion of their use and limits of applicability. Due to the

self-explanatory nature of this report, it will not be discussed

in detail here. It should be pointed out, however, that Nelson

[2] has put most of these equations into a computer program whicn

can be operated on a small desk top computer. This program is

not a fire model since it solves each equation independently.

Rather, it represents a simplification of use of the included

eq ua t io ns .

20
4. Models for Desk Top Computers

4.1 Fire Models

The fire models described below are of the ordinary differential

equation type and were originally developed on larger computers.

Advancements in desk-top computer technology and software allowed

their transferal to this computing environment. While each of

these models is available in a form which operates on IBM PC or

other MS-DOS machines, it should be noted that the more complex

models will require significant execution times on such small

machines for complicated cases.

The simplest of the engineering models is one developed by Cooper

called ASET for Available Safe Egress Time [3]. This is a simple

single compartment filling model which follows the development of

two stratified layers within a single compartment containing a fire. It predicts the upper layer temperature, smoke density,

species concentrations, and position of the interface between the

layers over time. While basically a single compartment code, it

has been used for two-compartment configurations where the code

is run first for the fire compartment and then the fire

compartment predicted values are used at the source terms for the

second compartment calculation. An additional feature provided

within ASET is the estimation of time to certain, specified

events. These times to events are calculated using the quasi=

steady-state approximation.

Another single compartment fire model which is considerably more

complex was developed by Smith and Satija at Ohio State

University [4], The OSU Model was developed in order to

extrapolate material properties measured in the OSU Heat Release

Rate Calorimeter [5] (ASTM E-906) to full-scale room

configurations. Thus, the input data required for this model are

those data provided by the OSU Test Method. This model is

considerably more complex than the ASET Code and provides more in

the way of predicted quantities. At present, this OSU Code is

the only available fire model that attempts to predict the

burning of wall lining materials.

The Harvard V Computer Code [6] represents another increase in

complexity over the OSU Code. It was developed by Emmons and

Mitler at Harvard University under a grant from the Center for

Fire Research. This model is not tied to any particular test

method but rather attempts to calculate fire development in a single compartment, including the combustion of multiple fuel

items, from basic principles and property measurements. Where

necessary, it does contain some empirical constants (for example,

a flame spread parameter) and represents the current state-ofart in modeling of the combustion process. As probably the most

mathematically complex code currently available on a personal

computer, the model will require the longest execution times of

any of these currently available models.

21
The final fire model to be discussed is the only multiple

compartment model currently operating on a personal computer.

The model, written by Jones, is called FAST for fire and smoke

transport [7]. While it does not contain the combustion

calculations available in Harvard V, the FAST Model is primarily

a fluid dynamics transport model which predicts the transport of

energy and mass produced by a burning item throughout multiple

Interconnected compartments. The model then predicts the

environment in each of these compartments over time in terms of

the temperatures, smoke densities, and various species

concentrations for up to twelve fire products. The FAST Code is

particularly capable in terms of its mathematical solving routine

and appears to be most capable of solving problems of interest in

a reasonable time and without encountering mathematical problems

which cause the program execution to stop (convergence problems).

4.2 Engineering Design and Evaluation Models

In addition to fire models, models have been developed for use in

engineering design and evaluation of fire protection systems and

building features. The first such model is called ASCOS for

Automatic Smoke Control Systems Model [8]. This model, developed

by Klote, is used for evaluating the design and operation of

smoke control systems in large buildings. It Includes such tall

building phenomena as wind and stack effect and the flow in

shafts such as elevator shafts and stairwells.

Another model which is useful for the prediction of the

activation time or required spacing for smoke detectors, heat

detectors, and automatic sprinklers is a model called DETACT-QS

developed by Evans and Stroup [9]. This model takes an input

heat release rate history for the burning object and calculates

the development of the fire plume and the resulting celling jet

in terms of its temperature and velocity as it impacts the heat

transfer to a thermally activated device such as a heat detector

or automatic sprinkler. In addition, based on the results of

experiments conducted by Heskestad at Factory Mutual, It can also

be used to estimate the activation time of smoke detectors. It

should be pointed out, however, that while usable for predicting

the activation time of automatic sprinkler heads, it does not

attempt to predict the delivery of the extinguishing agent to the

fire nor the extinguishing process. Nonetheless, the prediction

of activation time and the ability to account for the effect of

varying ceiling heights in the response of thermally activated

detectors and smoke detectors is useful, not only for the design

and installation of the systems, but also as an ancillary feature

to the fire models described above.

Finally, there are two major evacuation modeling programs

available for personal computers. The first is EVA CN ET*

developed by Francis and Kisko at University of Florida [ 13 ).

This is an evacuation optimization program which predicts the

shortest time necessary to evacuate a given structure. It is

22
quite user friendly and can be run on most small computers in

reasonable time.

The other evacuation model which is available for personal

computers is the Escape And Rescue Model developed by Alvord at

the Center for Fire Research [11]. This is not an evacuation

optimization model as is EVACNET+, but rather predicts specific

evacuation times for given building geometries and occupant

capabilities. In addition to unaided evacuation, it contains

features which allow the prediction of evacuation times for

handicapped or other occupants incapable of s e 1

f - e va cua t i o n in

that it includes the modeling of the rescue process by assigned

staff or fire department personnel. This is a considerably more

detailed program which would require significantly longer

execution times than the EVACNET+ model.

5. Data Sources

The biggest problem facing a potential user of any of the methods

described above (from hand calculations through computer models)

is obtaining the data required* by the calculat ional technique as

input. This is because most of these data involve properties

which are either not measured or not reported in traditional

property test methods.

Traditional test methods have been designed to produce pass-fail

answers. Such yes/no results are the easiest for code

authorities to enforce under the more traditional expert

judgement codes, but they provide no detail on the quantitative

performance of the material or product. Therefore, a new

generation of test methods is under development which provide the

needed property measurements.

Initially, these new generation test methods can serve a similar

purpose under traditional code structure by providing

quantitative rankings of material performance requiring that some

ranking categories be developed. These ranking categories can be

developed straightforwardly by testing traditionally acceptable

products and using these as points of reference in the overall

ranking process. This approach is similar to that which was used

to develop the flame spread categories (A, B, C, and D) as

applied to the Steiner Tunnel Test (ASTM E-84). Thus, the new

test method can be used to replace the traditional test methods

in the current code structure and at the same time begin to

produce the property measurement data bank necessary for the

predictive methods which will eventually lead to performance

based codes. An initial report containing such data for use in

models and calculations has been published recently by Gross

[ 12 ] .

23
References

1.

Lawson, J.R. and Quintiere, J.G., Slide Rule Estimates of

Fire Growth, NBSIR 85-3196, National Bureau of Standards,

Gaithersburg, Md . 20899, June 1985.

2. Nelson, H.E., "FORMULAS" - A Computerized Collection of

Convenient Fire Safety Computations, in press , National Bureau of Standards, Gaithersburg, Md . 20899.

3. Cooper, L.7., A Mathematical Model for Estimating Available

Safe Egress Time in Fires, Fire and Materials, Vol. 6,

Nos. 3 and 4, 135-144, 1983.

4. Smith, E. and Satija, S., Release Rate Model for Developing

Fires, presented at the 20th joint ASME/AIC National Heat

Transfer Conference, Aug. 1981.

5. A STM Fire Tests of Building Construction and Materials

(E 906), American Society for Testing and Materials,

Philadelphia, Pa.

6. Mltler, H.E. and Emmons, H.W., Documentation for CFC V,

The Fifth Harvard Computer Fire Code, NBSGCR 81-344,

National Bureau of Standards, Gaithersburg, Md . 20899,

Oct. 1981.

• 7. Jones, W.W., A Multicompartment Model for the Spread of

Fire, Smoke, and Toxic Gases, Fire Safety Journal, Vol. 9,

Nos. 1 and 2, May/July 1985.

8. Klote, J.H., A Computer Program for Analysis of Smoke

Control Systems, NBSIR 82-2512, National Bureau of

Standards, Gaithersburg, Md . 20899, June 1982.

9. Evans, D.D. and Stroup, D.W., Methods to Calculate the

Response Time of Heat and Smoke Detectors Installed Below

Large Unobstructed Ceilings, NBSIR 85-3167, National

Bureau of Standards, Gaithersburg, Md . 20899, Feb. 1985.

10. Kisko, T.M. and Francis, R.L., Network Models of Building

Evacuation: Development of a Software System, NBSGCR

84-457, National Bureau of Standards, Gaithersburg, Md

20899, May 1984.

11. Alvord, D.M., The Escape and Rescue Model: A Simulation

Model for the Emergency Evacuation of Board and Care Homes,

NBSGCR 83-453, National Bureau of Standards, Gaithersburg,

Md. 20899, Dec. 1983.

12. Gross, D . , Data Sources for Parameters Used in Predictive

Modeling of Fire Growth and Smoke Spread, NBSIR 85-3223

National Bureau of Standards, Gaithersburg, Md . 20899,

Sept . 198 5 .
FIRE DETECTION AND ALARM SYSTEMS

Richard W. Bukowskl, P.E. , Head

Hazard Analysis

Center for Fire Research

National Bureau of Standards

Fire Detection

1. Fire Signatures

Fire detectors sense the presence of fire by responding to changes in

their local environment which are indicative of a fire within their associated

area of coverage. The goal is to select conditions for sensing which appear

as early as possible and which are present at levels sufficiently above those

which might be produced by non-fire conditions to minimize false alarms* Such

conditions are referred to as fire signatures* Not all unwanted fire conditions produce all fire signatures, so optimum detector system design .requires

that the detector types selected must be matched to the hazard present.

1.1 Heat

Combustion is essentially an exothermic, gas phase chemical reaction.

Gaseous fuels combust by breaking bonds in the fuel molecules forming other

chemical species and releasing thermal energy. For solid or liquid fuels,

some of the thermal energy is needed to produce the phase change to a gas

before the actual combustion takes place. This required energy is the heat of

gasification. The net remaining energy then goes to increase the temperature

of the gases and air leaving the combustion zone. This hot gas rises due to

buoyancy to the ceiling and spreads radially outward in a ceiling jet. The

25-
temperature and velocity of this ceiling jet govern the heat transfer rate to

thermally activated detectors located on the ceiling.

1.2 Smoke

In terms of fire detection, smoke refers to solid or liquid particles

released during combustion. The solids are clusters of carbonaceous spherules

formed within the fuel rich portions of the flame in a process similar to

polymerization. Vapors can condense on a solid core, yielding a liquid

covered smoke particle. This condensation process requires that the temperature be below the vaporization temperature while the vapor concentration is

still high. In smoldering combustion, essentially all the smoke is in the

form of condensed vapors. This is why the smoke from smoldering appears light

colored (the liquid is largely water) and the smoke from flaming is dark

(mostly carbon). This also means that the particle size from smoldering is

larger than from flaming.

1.3 Light

Flames radiate light energy over a broad spectrum. Radiation in the

visible and infrared comes largely from thermal energy radiating from the

carbon particles within the flame. This is why a hydrogen flame which

contains no carbon is invisible. Ultraviolet radiation comes largely from OH

radicals and the thermally broadened OH radiation explains why alcohol flames

and premixed gas flames appear blue.

26
1.4 Transport/Losses

Once produced by the fire, the fire signature must travel to the detector

to produce a response. Depending on the signature, this transport process

takes time, and losses can occur which further delay response. An understanding of this process can help to select optimum detector placement and

type for the fastest response to the hazard.

The rising plume above a fire entrains cool air which reduces the

temperature and dilutes the particulate concentration. Once it contacts the

ceiling, heat transfer reduces the temperature further but particulate losses

to the ceiling are generally small. When the ceiling jet reaches the detector

the thermal inertia of a heat detector results in a delay in response, but a

smoke detector will respond immediately if the particulate concentration is

high enough. This is the primary reason why smoke detectors respond faster

than heat detectors for most fires.

With flame detectors, the light energy travels in a straight line almost

instantaneously. Since the fire is radiating in all directions, the intensity

falls off as the square of the distance from the fire to the detector and may

be attenuated by any smoke particles through which it must pass. The key

thing to remember about flame detection is that the detector must be able to

"see” the flame directly, although infrared energy will reflect from surfaces

at a reduced level.

-27-
2. Types of Detectors

2.1 Heat Detection

Heat detectors are the oldest , simplest , and least costly of the fire

detectors in use today. The oldest physical principles used involve the

melting or expansion of an element exposed to the environment. Newer types

employ the thermoelectric principle (thermocouples), changes in electrical

conductivity (thermistors), or the release of a gas adsorbed in a porous salt.

Heat detectors are designed to activate either at a fixed temperature or

to a specified rate of temperature rise or both. Rate of rise type detectors

normally include a fixed temperature element so that a slowly developing fire

will not produce excessive temperatures before detection. Because of their

generally slower activation, heat detectors are normally used for property

protection.

2.2 Smoke Detection

Smoke detectors are more costly and complex but are considerably faster

in detecting fires. They fall in two major categories, ionization and photoelectric (optical) types.

2.2.1 Ionization Type

Ionization type detectors use a small radioactive source to produce Ions

(charged air molecules) between two electrodes across which an electric

28
voltage is maintained. This voltage causes the ions to move to the electrodes

and discharge. This charge transfer is an electric current. When smoke

enters the chamber the ions attach themselves to the smoke particles and do

not contribute to the current flow. This reduction in current is proportional

to the number of smoke particles present. When the current drops to a

specified level, an alarm is produced. This signal proportionality to the

number of smoke particles makes the ionization type detector particularly

sensitive to flaming fires which produce very large numbers of small

particles

2.2.2 Photoelectric Scattering Type

Photoelectric type detectors sense particle concentration optically by

the fact that light is absorbed, reflected, or refracted by smoke. Two subtypes of photoelectric detectors are scattering and extinction. The

scattering type uses a light source and receiver so arranged that light from

the source does not normally strike the receiver. With smoke present, light

is reflected or refracted at an angle which causes it to strike the receiver.

Scattering type detectors have the advantage of small physical size and are

the most common. A disadvantage is that they are generally less sensitive to

absorbing (dark) smokes since they absorb a portion of the incident light,

reducing the amount of light which reaches the receiver.

2.2.3 Photoelectric Extinction Type

Extinction type detectors use a source and receiver in a direct line.

Smoke attenuates the received light by absorption, reflection and refraction.

29
so they are not affected by particle color. The disadvantage is that they

require a significant separation between the source and receiver (attenuation

path) for proper signal sensitivity. Thus the source and receiver are

normally separate units and the beam path is projected across the protected

space.

Due to the physics involved, an optical detector’s signal is proportional

to the mass concentration of particles present. This favors larger particle

diameters (and lighter colors) associated with smoldering fires.

2.3 Flame Detectors

Flame detectors sense the infrared (IR) or ultraviolet (UV) radiation

emitted by flames. They are generally the most costly, fastest, and most

false alarm prone of the fire detectors in use today. Thus their use is

normally restricted to "high hazard" situations.

2.3.1 Infrared Type

Infrared radiation is emitted by almost any hot object. Thus, IR

detectors need a second signal to differentiate flames. They normally use the

principle that flames "flicker” at a characteristic range of frequency (5 to

30 Hz). Other discrimination principles used Include looking at two or more

wavelengths. Including the combination of IR and UV.

30
2.3.2 Ultraviolet Type

With two notable exceptions, ultraviolet detectors do not need additional

discrimination since the wavelengths used only appear in flames. First, the

sun emits a narrow UV line within the flame range. This can be filtered out

to make the detector "solar blind". The second exception is that an

electrical arc is a very strong, broad band UV emitter. Thus UV detectors are

very sensitive to arcs.

3. Selection of Detectors

When laying out a fire detection system the design engineer must keep in

mind the operating characteristics of the individual detector type as they

relate to the area protected. Such factors as type and quantity of fuel,

possible ignition sources, ranges of ambient conditions, and value of the

protected property are critical in the proper design of the system.

Intelligent application of detection devices using such factors will result in

the maximization of system performance.

Heat detectors have the lowest cost and false alarm rate but are the

slowest in response. Since heat tends to dissipate fairly rapidly (for small

fires), heat detectors are best applied to the protection of confined spaces,

or directly over hazards where flaming fires could be expected.

Heat detectors are generally installed on a grid pattern at their

recommended spacing schedule, at reduced spacing for faster response, or where

beams or joists may slow the spread of the hot gas layer.

31
The operating temperature of a heat detector is usually selected at least

25°F above the maximum expected ambient temperature in the area protected.

Pneumatic heat detection systems have a device known as a "blower heater

compensator" which is used to prevent false alarms due to the sharp initial

heat rise from ceiling-mounted unit heaters.

Smoke detectors are higher in cost than heat detectors but are faster

responding to fires. Due to their greater sensitivity, false alarms can be

more frequent, especially if they are not properly located.

Smoke detectors do not have a specific space rating except for a 9 meter

(30-foot) maximum guide derived from the UL full-scale approval tests which

they must pass. Grid type installation layouts are usually not used since

smoke travel is greatly affected by air currents in the protected area. Thus,

smoke detectors are usually placed by engineering judgment based on prevailing

conditions.

Since smoke does not dissipate as rapidly as heat, smoke detectors are

better suited to the protection of large, open spaces Chan heat detectors.

Smoke detectors are more subject to damage by corrosion, dust, and

environmental extremes than the simpler heat detectors because smoke detectors

contain electronic circuitry. They also consume power, so the number of smoke

detectors which can be connected to a control unit may be limited by the power

supply capability.

32
Photoelectric smoke detectors are particularly suitable where smoldering

fires or fires involving low temperature pyrolysis of ?YC wire insulation nay

be expected. Ionization smoke detectors are particularly suitable where

flaming fires involving any other materials would be the case. The particle

counter detector responds to all particle sizes equally, so they nay be used

without regard to the type of fire expected. These systems, however, are

fairly expensive and complex to install and maintain. The design and layout

of the sampling tubes is critical ana must be done by someone familiar with

the equipment.

Flame detectors are extremely fast responding but will alarm to any

source of radiation in their sensitivity range, so false alarm rates are high

if they are improperly applied. Flame detectors are usually used in

hyperbaric chambers and flammable material storage areas where no flames of

any sort are allowable.

Flame detectors are "line of sight" devices, so care most be taken to

ensure that they can " see" the entire protected area and that they will not be

accidentally blocked by stacked material or equipment. Their sensitivity is a

function of flame size and distance from the detector, and some detectors car.

be adjusted to ignore a small flame at floor level. Their cost is relatively

high but they are well suited for areas where explosive or flammaole vapors or

dusts are encountered as they are usually available in "explosion proof"

housings

Table 1 contains a summary of the information contained in this section.

33
Systems

4. System Features

The fire alarm systems to which the detectors are connected provide many

features of operation in response to code requirements. The best way to

understand the concepts involved is to discuss systems design and operation in

terms of these features.

4.1 Power Supply

All systems are required to have at least two independent sources of

power. The primary source is normally from the public utility and the

secondary supply from rechargeable batteries (within or near the panel) or

from an engine driven generator where such is present for other purposes (such

as in a hospital). Switching from the primary to the secondary source is

automatic and such switching produces a trouble signal to notify maintenance

personnel that the primary source has failed.

4.2 Supervision

This refers to the monitoring of the integrity of the signal transmission

paths which interconnect the system components (e.g., the field wiring). The

occurrence of any single fault, such as a broken wire or ground fault, which

prevents the normal operation of the system must produce a trouble signal.

Where a high level of reliability is needed, circuit arrangements which will

continue to operate in spite of a single fault are available.

34
4.3

Signal Initiation

Signal initiation relates to the initiation of a fire alarm signal. This

can occur by the activation of an automatic detector, a manual fire alarm

station, or a water flow device within an automatic sprinkler system.

4.4 Indication/Notification

Signal indication refers to the process of notification of the existence

of a fire. The Important considerations here are who is to be notified and

how they are to be notified. For building occupants, a combination of audible

and visible devices are used. In large buildings where anything other than

complete, immediate evacuation of all occupants is contemplated, voice message

systems are used where specific instructions can be given to the occupants

from a central location in the building.

4.5 Signal Transmission

This relates to the automatic transmission of alarms to the fire

department. This may be done directly or through a privately operated alarm

monitoring facility. In the U.S., unlike most other countries, most fire

alarm systems are not connected to call the fire department automatically.

The reasons for this are unclear, but are probably based on tradition.

Transmission is largely by wire pairs leased from telephone companies,

although, in recent years, radio transmission techniques have been developed.

35
4.6

Hard Wire/Multiplex

Traditionally, signal transmission on wires within a building has been on

individual dedicated circuits containing one or more initiating or indicating

devices within a room or section of the building. Modern electronics has now

allowed a significant reduction in the required wiring by multiplexing

(mixing) signals on a single wire pair. Groups of devices on this pair are

identified with an address and thereby maintain their distinction from other

groups of devices.

4.7 Addressable Systems

The next step from multiplex is where each device has its own address.

By this process all devices can be on one pair and can be individually

controlled. Inquiries on the status of every device are made automatically by

the system, performing the function of supervision as well as operation.

4.8 Analog Systems

The newest concept is the detector which transmits data to the panel on

its signal level. This allows the signals to be analyzed and compared and a

decision algorithm to be applied to decide whether an alarm should be produced

or what level of response is needed. Such a system can drastically reduce

false alarms.

36
5. Testing and Maintenance

A detailed guide on testing of complex fire alarm systems has recently

been produced. The important concepts contained here (beyond the details of

testing procedures and schedules) are as follows.

After initial installation or any major modification, an acceptance test

is performed where every device in the system is tested for proper operation.

If successful, the system is certified by the installer/contractor that it is

fully operational.

A reduced scope recertification test is then required every 5 years, with

sample testing of individual devices specified at shorter Intervals.

37
Table 1. Summary of Detector Application Considerations

Detector

Type

Response

Speed

False Alarm

Rate Cost Application

Heat Slow Low Low Confined Spaces

Smoke Fast Medium (tedium Open or Confined

Spaces

Flame Very Fast High High Flammable Material

Storage

Particle Fast Medium High Open Spaces - High

Value
FIRE STATISTICS AND THEIR USE IN FIRE PROTECTION

Richard L. P. Custer

Associate Professor and Associate Director

Center for Fire Safety Studies

Worcester Polytechnic Institute

Introduction

Each time there is a fire incident, whether it is in a

residence or a factory, a variety of people and agencies will

need to have questions answered about when, where and how the

fire started, what the losses were and what factors contributed

to the loss. The extent and detail of the data needed will vary

widely depending of who the data user will be. Data may be

needed to establish the value of insurance claims, to provide

budget input and performance measures for the fire department or

to allow the code officials and the design communities to

evaluate the effectiveness of fire protection and fire prevention

measures

The purpose of this paper is review the basic elements of

fire incident reporting and to discuss the potential uses of fire

statistics as related to "specif ic user groups. In addition,

various techniques will be presented to provide guidance for the

analysis of fire statistics.

Fire Reporting Data Elements

The information collected in any data system is largely user

dependent and the larger the number of different user needs, the

larger and more complex the system will be. A partial list of

users includes fire departments, code writers, regulatory

authorities, standards committees, insurance companies,

researchers, industry and the design community (1). While the

specific needs of these groups are often highly specialized,

many data requirements are the same. Thus it is important for

data to be collected in a consistent manner regardless of the

source if members of the fire protection community at large are

to interact with each other.

Developed by the National Fire Protection Association

( NFPA ) , NFPA 901, Uniform Coding for Fire Protection , provides a

core of fire incident data elements that can be used to provide

basic information for a wide range of users (2). These elements

have specific definitions and describe the essential facts of a

given fire incident. This guide for coding of fire incident data

serves as the basis for the National Fire Incident Reporting

System in the United States ( NFIRS ) (3) and is also used at the

state and local levels. Australia is presently in the process of

adapting NFIRS as the Australian Fire Incident Reporting System

( AFIRS )( 4 ) . Although NFPA 901 provides data elements for both

39
property damage and casualty (death or injury) reporting, the

following overview will focus on property damage.

Since many factors relating to a fire are dependent upon

the use of the property involved, an extensive coding system is

provided for this data element. Broad categories, such as

"public assembly", "health care" and "industrial" have been

chosen to be consistent with the same terms as used in building

codes and fire protection design standards. Characteristics of

the building, such as construction type and method, age of the

building, size and value, are identified. Here, for example,

it would be noted whether or not the building was of fire

resistive construction. Exit features, interior finish and fire

protection features such as protection of vertical openings and

the extent of sprinkler or detection system protection provided

can also be described. Data elements for the activities of the

fire department are also provided.

The area of origin and factors resulting in the ignition are

also detailed. Equipment involved in the ignition and the form

of the heat of ignition are included as well as the form of the

material ignited. Forms of materials include building

components, furniture, apparel, etc. The type of material

ignited is often a critical factor in the outcome of a fire and

is classified in NFPA 901 as wood ("naturally occurring fuels"),

gas, flammable liquids, chemicals," plastics, etc.

An ignition factor classification is provided to describe

the circumstances that permitted the ignition source to act upon

the first material ighited. This element can be essential to

development of preventive measures. Ignition factors include

incendiary, misuse of heat or materials as well as mechanical,

design and operational deficiencies. In addition to the ignition

factors, data elements to describe factors contributing to flame

and smoke travel are enumerated. Vertical and horizontal

openings, interior finish materials and building contents are

among the choices.

Performance of the fire department or the built-in fire

protection systems is important information for the assessment of

fire safety measures. Data elements here address such problems

as delay of alarm or agent application in terms of detection and

automatic or manual suppression.

Specific attention is also paid to measurement of fire

losses and manpower use. Here, data elements are provided to

distinguish between the damage directly from fire and that from

the efforts to suppress the fire. The number of people made

homeless or the number of businesses made unusable can also be

reported along with the estimated total property damage.

NFPA 901 also provides guidance for the collection of data

relative to the location of the incident, date and time of the

alarm and time that the fire department arrived at the scene.

40
Fire Reporting Systems

As can be readily seen from the brief discussion above, it

is unlikely that any one user would either have need of or the

resources to collect all the data elements in NFPA 901 . What is

necessary is for users to develop a selection of elements

that suit their specific needs using NFPA 901 as a guide. In

some cases, users may have to develop their own "custom" elements

perhaps as part of a special study or project.

Simply having a collection of data elements that meet a

specific need is not necessarily a "reporting system." The system

must include the data gathering step (report forms and manuals),

data processing (manual vs computer based) and data analysis.

It should be noted that the results of any fire data

analysis are only as good as the quality of the input. Training and quality control In the filling out of reports and entering

data are essential. Error traps can be built into computer

programs to reject clearly ambiguous reports such as one that

indicates a $300,000 loss in a fire that was "out on arrival."

Data Analysis

The simplest form of data analysis would be the generation

of summary statistics. These data are often produced for annual

reporting purposes and deal with broad categories of fire

information. The NFPA reports summary data annually for fire

losses in the United States. For, the year 1984, the estimated

number of fires reported was 2,343,000, the civilian deaths were

5,240, the civilian injuries were estimated to be 28,125 and the

property losses were projected to be 6.7 billion dollars (5). In

this report, the summary data were placed in perspective by

including the percent change from the previous year, +0.7

percent, -11.5 percent, -10.1 percent and +1.7 percent

respectively.

Summary data are also provided for losses as a function of

broad property use types such as casualties in residential and

non-residential . For a more detailed picture of the residential

casualties, this category is broken down into "one- and twofamily, apartments, hotels and motels and "other." Data for the

NFPA summaries comes from a survey in which a stratified sample

of fire departments is sent a questionaire regarding their past

year's fire experience.

Summary data for the United States is also collected using

the NFIRS system described above (3). In this instance, the data

comes directly from fire incident reports that are collected and

summarized at the state level. Data from the participating

states is aggregated and analyzed at the national level by the

Federal Emergency Management Agency.

Other ways to display summary data Include losses per

41
population unit (per 10,000, per 100,000, per million,

etc.), losses per monetary unit invested in fire protection (fire

department costs, cost associated with code requirements, etc.)

and ranking fire cause data by frequency of occurrence. Trends

can be shown by plotting summary data over a number of years.

While summary data are useful for providing a general

picture of fire experience over time, a more insightful analysis technique is fire scenario analysis. A fire scenario is the

description of a sequence of events that caused an ignition and

the results of that ignition. Once this sequence has been

identified, action can be taken to interrupt the sequence in

order to prevent the ignition or modify the outcome of the fire.

A scenario should contain at least the following elements to

describe an incident (6).

ELEMENT

TYPE OF LOSS

OCCUPANCY ( propertry use

)

TIME

OCCUPANT CONDITION

IGNITION SOURCE

ITEM FIRST IGNITED

DIRECT CAUSE OF LOSS

EXAMPLE

DEATH/ INJURY

RESIDENTIAL

NIGHT

ASLEEP

SMOKING MATERIALS

FURNITURE

SMOKE AND TOXIC GAS

Other scenario elements that could be included are type of

construction, location of the incident, presence or absence of a

smoke detector, ignition factors, etc. In industrial

applications, ignition source may be broken down into equipment

involved and form of heat of ignition.

Based on the information available in the user's data base

and the level of analysis, the number of elements in a scenario

may vary. Once the scenario elements have been selected, the

data base is sorted and the results ranked by frequency of

occurrence

The following is an example of the results of a scenario

analysis of one- and two-fatality fires in the United States from

1971 to 1978 (7)
HEAT OF IGNITION

DEATHS

MATERIAL IGNITED AREA OF ORIGIN % OF

Cigarette Furniture Living Area 17.3

Cigarette Bedding Sleeping Area 14 .

Vehicle Crash

( highway)

Fuel Fuel Tank 3 .

Match, Lighter

Candle

Bedding Sleeping Area 2

3

Heating, Cooking

Equipment

Structural

Component

Living Area 1 .

Cooking Equipment Clothing on

Person

Kitchen 1.5

Although the above represents only a portion of the results,

it can easily be seen that if the firesafety objective is to

reduce one- and two-fatality fires, the biggest impact could be

made by attacking those scenarios involving cigarettes in contact

with furniture or bedding. Four possible strategies might rfow be

proposed... firesafe cigarettes; smoulder resistant furniture,

mattresses and bedding; early alerting of occupants through

expanded use of smoke detectors, and early suppression of the

fire by automatic sprinklers. Clearly, additional study of the

costs and relative benefits of the alternatives would be

necessary before a final strategy could be selected. Discussion

of the various techniques of decision analysis is beyond the

scope of this paper. A thorough decision analysis of the

cigarette-upholstered furniture scenario can be found in

reference 8.

Data Users

As previously mentioned, there are a wide variety of

potential users of fire statistics. In the discussion to follow,

some of the user groups will be Identified along with examples of

how the data might be used to meet objectives. It should be

noted, however, that in many instances, the needs of several user

groups will be found within a single organization. This is often

the case, for example, when the fire department has

responsibility for development and administration of the fire

portions of a building code. A second example might be a large

manufacturing company that has its own fire brigade and

corporate loss prevention program.

The fire department is the principal generator of fire

statistics and is often in the position to make the most

immediate use of the data. Sudden increases in the frequency of
a particular type of fire, for example, may be dealt with by a

targetted inspection or fire prevention education program.

Monitoring of the frequency of the targetted fires over a period

of time can be a measure of the effectiveness of a special

prevention program. High work loads in a particular fire

district can be identified and used as the basis for budget

requests or reallocation of resources. Concentration of

suspicious fires in a particular area of a city or plant may

justify surveillance or studies of the ownership, fire and

insurance history of the premises in question. These activities

often lead to the identification of possible arsonists.

People and organizations that develop laws, regulations and

test methods also make use of fire statistics. High death rates

or property losses from a particular fire scenario can focus

attention and lead to solutions. The following example from the

United States experience how this process is carried out.

In 1953, in response to serious injuries from ignition of

brushed rayon sweaters ("torch sweaters"). The Flammable Fabrics

Act became law. The test method required by the law for apparel

fabrics screened out those that were so highly flammable as to be

dangerous (i.e. like the torch sweaters) (9). In 1970, a National

Bureau of Standards study of detailed reports of burn injuries

from apparel fires revealed that young children (0 to 5 years)

wearing sleepware were injured more frequently than expected from

their percentage of the total population, 1.6 times for girls and

3.9 times for boys (10). A new test for children's sleepware

fabric was proposed that evaluated the candidate fabric under

ignition and burning conditions that more closely resembled

actual scenarios with the sample vertical rather than 45 degrees.

The proposed standard became law in 1971 for garments up to size

5X (11) and was later extended to include sizes 7 through 14

( 12 )

. In this example, statistics were used to identify a problem

area and the research and testing community used detailed

ignition scenario information to develop a proposed solution

directed specifically to the problem of reducing the number of

children injured in sleepware fires. Legislators and regulators

then reviewed the statistics and the proposal along with public

and industry responses and the laws were enacted.

Code authorities and committees responsible for development

of firesafety design practices have many uses for fire

statistics. If, for example, a code authority is considering new

requirements for installation of smoke detectors, a study of

effectiveness of similar requirements implemented in another

jurisdiction or occupancy would be helpful. Such a study might

compare the termination stage of the fire or the condition on

arrival of the fire department with the presence or absence of

detectors

A study of the extent of flame damage compared to number of

sprinkler heads opening for different materials ignited may help

44
improve design standards by identifying the need for greater

water application rate if certain materials are expected to be

involved. This same study would have value to an insurance

company in the process of establishing rates such that enough

premium is generated to cover losses . Many other examples can be

cited where the use of fire statistics is an essential part of

firesafety decision making and risk management.

Summary

If lessons are to be learned, past fire experience, data

about fires must be collected and studied by a variety of

interested parties. Selection of the data elements to be used in

any fire data system or special study must take into

consideration the specific needs and objectives of the user.

While NFPA 901 provides an extensive set of fire reporting data

elements, it may not be practical or necessary to collect them

all. In fact, some of the data elements needed for special

studies may not be included. In order to make any data system

useful to as many users as possible it is important to establish

a core of common data elements and definitions and to pay

particular attention to accuracy and quality control of the data.

References Cited

1. Derry, L. , "Fire Experience and Fire Protection," Fire

Protection Handbook, 15th Edition, National Fire Protection

Association, Quincy, MA, 1981.

2. NFPA 901 , "Uniform Coding for Fire Protection," National Fire

Protection Association, Quincy, MA.

3. "Fire in the United States," Second Edition, FEMA-22

,

Federal Emergency Management Administration, Washington, DC,

July 1982

4. Schaenman, P. S. and Seits, E. F., "International Concepts

in Fire Prevention Practices from Japan, Hong Kong,

Australia and New Zealand," TriData Corp. , Arlington, VA,

1985 .

5. Karter, M. J., Jr., "Fire Loss in the United States During

1984," Fire Journal, Vol . 79, No. 5, September 1985.

6. Clarke, F. B. and Ottoson, J., "Fire Death Scenarios and

Fire Safety Planning," Fire Journal, Vol. 70, No. 3, May

1976.

7. Derry, L. , "Fatal Fires in America: How They Happen, Where

They Happen, How to Stop Them," Fire Journal, Vol. 73, No.

5, September 1979.
8 . Helzer, S. G. , Buchbinder, B. and Offensend, F. L.

,

"Decision Analysis of Strategies for Reducing Upholstered

Furniture Fire Losses," NBS Technical Note 1101, U. S.

Department of Commerce, June 1979.

9. "Flammability of Clothing Textiles," Commercial Standard

191-53, U. S. Department of Commerce, Washington, DC, 1953.

10. U. S. Department of Commerce, "Children's Sleepware - Proposed Flammability Standard," Federal Register, Vol. 35,

No. 223, November 17, 1970, pp. 17670-17673.

11. U. S. Department of Commerce, "Standard for the Flammability

of Children's Sleepware," DOC FF 3-71, Federal Register,

Vol. 36, No. 146, July 27, 1971, pp. 14062-14073.

12. U. S. Consumer Product Safety Commission, "Standard for the

Flammability of Children's Sleepware, Sizes 7 through 14,"

FF 5-74, Federal Register, Vol. 39, No. 85, May 1, 1974, pp.

15210-15288.

4 6
FAILURE ANALYSIS AND ANALYTICAL FIRE INVESTIGATION

Richard L. P. Custer

Associate Professor and Associate Director

Center for Fire Safety Studies

Worcester Polytechnic Institute

INTRODUCTION

Failure in a firesafety context can be defined as a fire

event that results in personal injury, death, property or

monetary losses or in conditions that prevent buildings or

mechanisms from functioning as designed (1). The objective of

fire failure analysis is to use the on-site and background data,

the results of testing and the reconstruc t ion to identify the

primary and contributing causes of the failures and their

sources

The sources of failures include basic design, material or

equipment selection, material or equipment defects

(manufacturing) , construction or assembly, testing, postconstruction modifications, service conditions (wear and tear)

and unanticipated- conditions (abuse).

The abjective of a failure investigation is to determine the

primary cause of the fire, assess the importance of contributing

causes and to take corrective action through changes in codes and

design practices to prevent similar failures in the future.

Targeted inspection or public education programs may also result

from understanding the cause and origin. A complete failure

analysis can reveal the fuel and building and fire suppression

factors that resulted in the ultimate extent of flame and smoke

movement. The results of a failure analysis also provide input

to insurance loss adjustment and underwriting, and to civil and

criminal litigation.

THE ROLE OF TIME IN FAILURE ANALYSIS

A complete reconstruc t ion and failure analysis involves

de veloping a time history for the incident. Time provides the

framework for the analysis and can be viewed in two scales. The

two scales are the macro or pre fire scale, where time is in

increments of days, weeks and years; and the micro or trans fire

scale which is meausured in seconds, minutes and sometimes hours.

Through the r ec o ns t r uc t i o n process, events are placed in

time perspective. Events to be considered from this perspective

include those in pre fire history, as well the trans fire events

(those occurring from the point of established burning to
extinguishment). Failure analysis deals with the design,

construction and performance aspects of the incident in the

context of the applicable standards of design and state-of-theart knowledge and also as a function of time.

Time lines or event sequences are the best way to organize

reconstruct ion and failure analysis information (2, 3). In

constructing a time line, it is important to establish reference

events. A reference event can be described as an event that is

well documented in time and space and serves as a point of

reference. The issuance date of a building permit or the time of

arrival of the fire department apparatus are good examples.

Using time of arrival as a reference event, for example, other

events can be roughly placed in time as happening either before

or after arrival of the apparatus. Explosions and the collapse

of walls or roofs are further examples of typical reference

events.

A single line can be adequate for incidents having few

events. For more complex situations, separate time lines (on the

same scale) can depict the history of the building, evolution of

the "model codes," installation and maintenance history of a suppression system, human activity or any other time-related

aspect of the incident.

The sources of pre fire time line information include

building permits,, plans and specifications, inspection reports,

fire and building codes and the fire research and engineering

1 i ter a ture

The fire department incident report, recordings of fire

department radio transmissions during the incident, and personal

interviews with fire- fighters and other witnesses are among the

many sources of information for use in the development of trans

fire t i me 1 i nes

THE RECONSTRUCTION AND FAILURE ANALYSIS PROCESS

The basic steps of reconstruction and failure analysis are

examination of the scene, collection of background data, testing,

recons true1 on and failure analysis.

Fire Scene Examination

The examination of the fire scene is critical to the entire

reconstruction and failure process. During fire scene

examination, the physical and photographic evidence is gathe- e-: . The extent and kind of damage is documented during f ire sce^e

examinat ion.

As part of the fire scene examination, the investigator >* : 1 1 take as many photographs as passible. Each photograph should e

48
documented on a diagram with a description of the direction of

view and what is being shown. In addition, maps and diagrams

should be prepared which note the dimensions and interior layout

of the building, the location and degree of damage, location and

types of fuel materials, and the locations of victims. The

location of fire protection features such as fire walls,

detectors and suppression systems should also be noted.

Many buildings will be modified considerably over their

lifetimes. Consequently, reviewing the original plans of the

building would provide a false impression of the building at the

time of the fire. For this reason, recording the architectural

,

construction and fire protection features at the time of the fire

is very important.

When fire suppression systems are present, the investigator

should note the position of valves, locations of discharge

na::les and location and type of detectors used to operate the

system. With special agent systems (such as halon, COE or dry

chemical), agent storage tanks should be checked to determine

whether or not the system discharged as designed.

Careful study of the damage patterns, combined with

interviews and a knowledge of the ignition sources and fuel

materials present immediately prior to the fire should be used to

determine the area of origin and if possible the source and form

of heat of ignition and the type and form of the materials first

ignited (A-). Burn patterns such as "V’s", low burns and multiple

"points of origin" can often be misleading. Consequent 1 y , they

should only be used in establishing cause and origin when

unambiguous or supported by other physical evidence. It is often

very helpful, in visualizing conditions in the area of origin, to

physically reconstruct the scene by replacing items in their

original locations.

Interviews may be conducted at many different times in the

reconstruction and failure analysis process. However, those

taken at or close to the time of the incident can be especially

useful, particularly in describing the course of the fire.

Whenever possible, try to relate events described in interviews

to reference events for the time lines.

Data

Although some of the background data (such as activities

immediately prior to the fire) can be gathered at the scene very

soon after the fire, the majority of needed information will be

gathered 1 a ter

The investigator will obtain plans, permits and the codes in

effect at the time of approval, along with the specifications and

di awings for the fire protection features. These same materials

should also be obtained: (1) if the building experienced any

major modifications; (E) if the building’s fire protection

features were altered; or (3) if there has been a change of
occupancy. Since any of these changes may have influenced the

course of the fire, a review of these materials should be

undertaken during the reconstruct ion process. Codes applicable

at the time of any changes to the building as well at the time of

the fire should also be studied.

Additional background information that may be useful for the

reconstruction could include instruction or training manuals,

maintenance records, data on construction and interior finish

materials, previous fire history of the building or equipment

involved, the amount of any previous fire damage, and the

physical and burning char ac ter i s t i cs and the location of the

contents. The gathering of background information also involves

obtaining detailed statements from the building occupants as a way of determining the c i rcumstances that lead to ignition and

established burning.

Tes t i_ng

Reconstruct ion and failure analysis may involve three types

of testing: (1) standard tests of flammability properties; (2)

standard analysis of unknown materials; and (3) special tests

designed to establish burning behavior under conditions related

to a specific fire scenario.

The many standard tests of flammability properties include

flame spread of materials (5,6); fabric flammability (7,8); flash

point (9,10); and rate of heat release (11, 12). Analytical

laboratories conduct debris analysis using techniques such as gas

chromatography , mass spectroscopy and others to identify unknown

materials, particularly possible accel lerants . Metallurgical or

x-ray analysis are also useful techniques.

Special tests that attempt to replicate a given

fire are sometimes called "demonstrations," and can often be

e;< t r erne ly revealing in understanding the course of a particular

fire. However, the results of demonstrations can be misleading

or subject to question about whether or not the demonstration

represents what actually happened. Factors such as ventilation,

arrangement of the fuel or even the point of ignition can have a significant effect on the outcome of the test. In other words,

the specific conditions at the time of the fire must be well

understood and reasonably reproduced in the demonstration.

Special tests or demonstrat ions should be conducted under

laboratory conditions.

The fire reconstruction is an organized, step-by-step

portrayal of the most likely course of the fire in question from

the ignition sequence through established burning to the limits

of flame and smoke movement at the time of extinguishment,

based on the facts developed through on-the-scene investigate • background studies and testing. The reconstruction explai- s t *

50
fire growth within the compartment or area of origin, along with

the effects of barriers and automatic suppression systems on

spread and growth and of the effects of manual extinguishment.

The reconstruc t ion should also include an evaluation of how the

life safety features of the building performed, relative to

injury of loss of life.

In sorting through the facts to develop the reconstruc t i on

,

the investigator may find it useful to apply the system safety

techniques of Failure Modes and Effects Analysis ( FEMA ) and

Fault Tree Analysis (13). These methods help identify

alternative sequences of events that could lead to the observed

fire situation such as development of room flashover or fire

breaching a fire wall. The investigator may then evaluate the

alternatives against the evidence to determine the most likely

scenario. These techniques are particularly valuable where

complex or interrelated machinery, buildings or human activities

are i nvo 1 ved

Analysis of the ignition sequence is concerned with three

specific items: the size, nature and source of the ignition

energy; the physical and chemical properties of the fires

materials ignited; and the c i r cums tances (human or mechanical)

that brought the energy in contact with the fuel. In selecting

the most likely ignition source, the investigator must compare

the energy available from a candidate source with the ignition

energy requirements of the fuel in the given form. For example,

given the same material and heat source, ignition is more likely

for materials in finely divided form than for solid materials.

Energy available at the source ( temper ature , thermal radiation,

etc.), distance from the fuel to the energy source and time of

exposure to the source of energy are also factors that must be

cons idered

The circumstances which result in ignition generally involve

human or equipment failure. Human failures include factors such

as careless welding, poor housekeeping and improper selection or

misuse of materials. Valve rupture and combustion control

failure could be considered equipment failures. Ultimately, most

equipment failures can be traced to design, manufacturing,

installation, misuse or maintenance problems.

If it is assumed that established burning is achieved after

ignition, the investigator must determine why the fire continued

to full room involvement (flashover) or, in the absence of

compar tmentat ion (such as in a warehouse or industrial building),

reached the extent that it did. The investigator will evaluate a number of factors — including the rates of heat release of the

fuels, continuity of the fuels (proximity of fuel packages to one

another), location of fuels relative to walls, compartment

ceiling height, ventilation and interior finish--in making

these de ter1 nat 1 ons

Heat release rate is one of the more important factors. In

many instances, a fire that was reported to have grown or spread

51
"unusually fast" is characterized as suspicious or incendiary

when, in fact, the growth rate may have been due to a combination

of the burning properties of the materials and nature of the

compartment in which the fire burned. A number of studies have

been carried out to characterize the burning rates of materials

and furnishings. Data can be found in National Bureau of

Standards reports (14 - 17). The roles of heat release rate,

fire location and compartment geometry have been reported by

Lawson and Quintiere (IB). Their work includes methods to

estimate ceiling temperatures, smoke levels, time to flashover

and flame height. Guidance on estimating the likelihood that a given fire size and room ventilation combination can develop

flashover is provided by Babr auskias ( 1 9 ) . A number of

computer models are also available that may be used to "test"

various possible fire scenarios.

Caution must be used, however, when applying fire models and

calculations. Some models may not be accurate if room doors are

assumed to be closed. Others may yield misleading results if the

wrong heat release rate is used. It is important to study the

formulas and the input data on which each model is based. A

sensitivity study should also be conducted to determine the most

critical variables. This is particularly important when

assumptions must be made regarding the inputs.

The recons tr uc t i on also involves evaluating the performance

of automatic suppression systems in controlling the growth and

spread of the fire. Among the factors to be reviewed are the

appropriateness of the agent being used, and the response time of

the system as related to the detection devices used relative to

ceiling height and fire growth rate. In addition, the

investigator will review the location of the agent discharge

nozzles relative to the source of the fire, and agent

availability (rate of discharge, pressure and adequacy of

supply). The conformance of the system design and installation

with the recommended practices found in NFPA standards and

industry design and installation manuals should also be reviewed.

For example, a sprinkler system may have failed to control a fire

due to a very high ceiling (that delayed the response time),

combined with low water pressure that could not produce the

needed water flow rate.

Barrier performance evaluation focuses on the nature of the

barrier (rated or not rated), the cons t r uc t i on , the thermal

stresses to which it was exposed and the manner in which the

barrier failed. Barriers can fail either by passage of flame or hot gases through a small opening, a hot spot failure, or by

movement of flame and hot gases through open doors or barrie--

co 1 lapse resulting in a massive failure. Failure of opening

protection, poor construction practices, modifications to the

barrier after construction ( poke- throughs , etc.) and fire

stresses that exceed those assumed in the design are examples

the causes of massive failures.

Manual suppression activities, including those by a

52
municipal fire department or a plant fire brigade, can have

significant effect on the outcome of a fire. In the absence of

fire suppression systems, the response time of the fire

department will determine the size of the fire at agent

application. For ease of analysis, the response time can be

broken down into the following segments: detection time, alarm

transmission time, dispatch time, travel time and time from

arrival to agent application. Problems resulting in delays in

any of the above time segments will extend the limit of flame and

smoke trave 1

Examples of factors that could cause delays are the absence of

detectors, unoccupied building or an improperly designed

detection system. Equipment failure or fire apparatus out of

service can delay response time; weather, terrain, traffic or

condition of apparatus can extend the travel time.

Malfunctioning hydrants, blocked access or shortage of personnel

are examples of factors that could delay application of water.

The reconstruct ion may often consider the performance of the

building life safety system. This includes the detection and

alarm system and the building egress system. In addition to the

factors effecting detector response discussed above, the

audibility of alarms plays a role in life safety. Guidance on

this topic can be found in work by Nober (SO). Building egress

factors include the capabilities of the occupants and the number,

capacity and protection of the means of egress routes.

Ana_ly s_i s

A failure analysis is made by comparing the causes of

failures with the codes, standards, design practice and the

state-of-the-art technology. In the analysis, it is important to

identify noncomp 1 iance with the standard practices, but it is

even more important to note where compliance with the standards

failed to provide the expected or needed fire safety,. In either

event, the failure analysis should provide recommendations for

how the failures could have been prevented in the fire in

question or how the knowledge gained can be applied to preventing

similar failures in the future.

CONCLUSION

In many fire incidents, the sice of the loss does not appear

to warrant an in-depth analysis such as that outlined above and

only the big losses are studied in detail. Often, the need for a complete analysis may not be recognized until after the scene is

destroyed. Thus it is important to assure that at least the fire

scene and witness statements are adequately documented for

possible future use in reconstruction and failure analysis.

53
REFERENCES

1. Custer, Richard L. P.,"Fire Loss Investigation", Fire

» 16th Edition, National Fire Protection

Association, Quincy, MA , March 1986.

2. Benner, Ludwig, "Accident Invest icat ions : Multilinear Event

Sequencing Methods," Jgurnal of Safety Research, Vo 1 . 7,

No. 2, 1975, p. 67.

3. Ferry, Ted S . , Modern Accident investigation and Anaiy s i_s^

An Executive Guide, John Wiley 2* Sons, NY, 1981.

A. Uniform Coding for Fire Protection, NFPA 901, National Fire

Protection Association, Quincy, MA

5. Test for Surface Burning Char ac t er i s t i cs of Building

Materials, ASTM E84-81, American Society for Testing and

Materials, Philadelphia, PA, 1981.

6. Test for Flammability of Materials Using a Radiant Heat

Energy Source, ASTM E162-81, American Society for Testing and

Materials, Philadelphia, PA, 1981.

7. Standard for the Flammability of Clothing Textiles (CS-191-

53.), 16 CFR 1610, United States Code of Federal Regulations,

1953.

8. Standard for the Flammability of Childrens’ Sleepware: Sizes

0 through 6X, ( FF 3-71) 16 CFR 1615, United States Code of

Federal Regulations, 1971.

9. Test for Flash and Fire Points by Cleveland Open Cup, D92-'7 8,

American Society for Testing and Materials, Philadelphia, PA,

1978.

10. Test for Flash Point by Tag Closed Tester, ASTM D56-79,

American Society for Testing and Materials, Phi ladelphia, C A,

1979.

11. Standard Test Method for Heat and Visable Smoke Release Rate

for Materials and Products, ASTM E906-83, American Society

for Testing and Materials, Philadelphia, PA, 1983.

12. Babrauskas, V., et al, "Upholstered Furniture Heat Release

Rates Measured With a Furniture Calorimeter , " NBSIR 82-260A

,

National Bureau of Standards, Gaithersburg , MD, Dec. 1982.

13. Henley, Enerst J. and Kumamoto, Hiromitsu, Reliability

i09il]e§cii:g and Risk Assessment, Prentice Hall, Englewood

Cliffs, NJ, 1981

1A. Babrauskas, V., "Full Scale Burning Behavior of Upho 1 s t e 1" ed

Chairs," NBS Technical Note 1003, National Bureau of

Standards, Ga i ther sbur g , MD , August 1979.

54
15. Babrauskas, V., "Combustion of Mattresses Exposed to Flaming

Ignition Sources Part I: Full Scale Tests and Hazard

Analysis, " NBSIR 77-1290, National Bureau of Standards,

Gaithersburg, MD , 1977.

16. Lee, Billy T., "Heat Release Rate Character istics of Some

Combustible Fuel Sources in Nuclear Power PLants," NBSIR 85-

3195, National Bureau of Standards, Gaithersburg , MB, 1985.

17. Walton, William D. and Twilley, William H . , "Heat Release and

Mass Loss Rates for Selected Materials," NBSIR 84-2960,

National Bureau of Standards, Ga i ther sbur g , MD, Dec. 1984.

18. Babrauskas, V., "Estimating Room Flashover Potential," Fire

I®E!2D£i.2S^ » Vo 1 . 16, No. 2, 1900, p. 94.

19. Lawson, J. R, and Quint iere, J. G., "Slide Rule Estimates of

Fire Growth," NBSIR 85-3196, National Bureau of Standards,

Gaithersburg, MD , June 1985.

20. Nober , E. H„, et al, "Waking Effectiveness of Houshold Smoke

and Fire Detection Devices," NBS GCR-80-284, National Bureau

of Standards, Gaithersburg, MD , 1984.

5 5
i

56
FIRE ORGANIZATION IN THE UNITED STATES

Andrew J. Fowell

Chief, Fire Safety Technology Division

Center for Fire Research

National Bureau of Standards

Gaithersburg, MD USA

INTRODUCTION

There is no single organization in the United States with overall

responsibility for fire safety. Fire protection standards,

services, research and education are handled by a variety of

private sector organizations, federal, state, and local

governments and universities. The primary body involved in the

development, publication and dissemination of fire safety

standards in the USA is the National Fire Protection Association.

The major organization which develops standard test methods to

measure the fire properties of materials is the American Society

for Testing and Materials. Public fire protection at the local

level is provided by over 28,000 independent fire departments.

The Society of Fire Protection Engineers is the professional

technical organization of qualified fire protection engineers.

The Center for Fire Research is the focal point for fundamental

and applied fire research in the USA, and the University of

Maryland is the only academic institution currently offering an

accredited 4 year undergraduate degree program in fire

protection. This paper provides further details of the

activities of these and other private and government

organizations associated with fire protection.

STANDARDS

Federal Regulations, Specifications, and Standards

Several Government agencies (e.g. Housing and Urban Development,

Transportation, Occupational Health and Safety) have regulatory

authority for specific activities and products, and reference

federal, national concensus or industry standards and

specifications in their codes and standards. Most of the Federal

specifications and standards prepared previously by Government

agencies for regulation, procurement and quality control

purposes, have been replaced by national concensus standards

developed by private standards writing organizations such as the

National Fire Protection Association, the American Society for

Testing and Materials and Underwriters Laboratories.

The National Fire Protection Association (NFPA)

NFPA is a non-government, voluntary membership, non-profit

organization with its headquarters in Quincy, Massachusetts,

57
(near Boston). It has a membership of approximately 32,500

individuals, 140 national trade and professional organizations,

and a staff of more than 200.

Activities of NFPA fall into two main areas, technical and

educational. The technical activity involves development,

publication and dissemination of standards which form the basis

for voluntary fire safety practice and for mandatory building and

fire code requirements. Each standard is published as an

individual booklet and all appear in the annual, multi-volume set

of National Fire Codes. The most widely used individual booklets

are the National Electrical Code, the Life Safety Code and the

Flammable and Combustible Liquids Code. The educational activity

involves promoting public adherence to the standards and making

good fire safety habits a way of life. In addition to its

standards and codes. NFPA publishes a number of books including

the Fire Protection Handbook, now in its 15th edition, a quarterly technical journal and a monthly magazine. NFPA also

assembles and analyzes national fire loss statistics based on

data provided by state fire marshals and performs on-site

investigations of significant fires. At its annual meeting in

May each year NFPA hosts a major fire safety exhibition of fire

protection equipment and services.

American Society for Testing and Materials (ASTM)

ASTM is a non-government, non-profit, scientific and technical

organization that develops standards on the characteristics and

performance of materials, products, systems and services. Of the

137 main technical committees only one is primarily concerned

with fire. It is Committee E5 on Fire Standards. It monitors

and regularly updates approximately 20 standards, of which the

most widely known are E 84 Test for Surface Burning

Characteristics of Building Materials. E 119 Fire Tests of

Building Construction Materials, and E 152 Fire Test of Door

Assemblies and E 108 Fire Tests of Roof Coverings. Other

standards involve measurements related to combustibility, flame

spread and smoke generation, and recently Committee E 5 has added

combustion toxicity, risk assessment and fire modeling to its

areas of activity.

SERVICES

Testing Services

Fire testing of materials and products is generally not a government function in the United States, it is performed bv

private laboratories such as Underwriters Laboratories Inc.,

United States Testing Co., Inc., Southwest Research Institute,

Factory Mutual Research Corp., and university laboratories,

has become common practice for safety authorities in state and

local jurisdictions to recognize the results from independent

testing laboratories rather than set up their own facilities.

58
Fire Services

In the U.S. there are over 28,000 fire departments providing

public fire protection at the local level. Depending on size

and location of the city or area covered, the fire departments

may consist of career (paid) firefighters, volunteer

firefighters, or a combination. Fire departments vary widely in

size, the largest being New York City which protects more than 7 million people, has 12,000 fire fighters, and operates on a budget of more than 4 million dollars. The two major

organizations representing fire service personnel are the

International Association of Fire Chiefs and the International

Association of Fire Fighters. The chief fire protection

administrator at the state level is called the State Fire

Marshal, and the State Fire Marshals Association of North America

serves as the principal organization of fire marshals, fire

prevention officers and fire investigators.

RESEARCH

The Center for Fire Research (CFR)

The Center for Fire Research at the National Bureau of Standards

is located in Gaithersburg, Maryland close to Washington, D.C.

With a staff of more than 100, CFR' s scope extends from

exploratory research on combustion to the development of computer

programs to solve practical fire protection engineering problems.

The program includes flammability and toxicity measurement, fire

growth and extinction phenomena, room fire modeling, hazard

analysis, fire simulation, fire performance and validation

testing. In addition to its own inhouse research the Center also

provides grants to nearly thirty universities. Approximately 50%

of the work of the Center is performed for other Federal

agencies.

Other Federal Fire Research Laboratories

Fire research programs are underway at a number of other Federal

laboratories. These include the Forest Service, the Naval

Research Laboratory, other defense laboratories, the Federal

Aviation Administration and the Consumer Product Safety

Commission. These and other Federal agencies sponsor research at

government, private and university laboratories. These programs

are much narrower in scope, more applied, and mission oriented

than that of the Center for Fire Research.

Private Sector Research Laboratories

Factory Mutual Research Corporation (FMRC), located near Boston,

is the leading fire research laboratory outside the Federal

government. It is supported by a group of insurance companies to

provide guidance on protecting properties they have insured to

minimize their risk. It has a well equipped large scale test

59
facility which has been used to pioneer the development of fire

suppression systems for warehouse storage protection.

Southwest Research Inc. (SwRI), an independent research

organization located in San Antonio, Texas has a department of

fire technology. The primary focus of the work in fire at SwRI

is on the evaluation of the fire performance of construction

materials and the investigation of the toxicological effects of

smoke and gases produced in fires.

Underwriters Laboratories Inc. performs some fire research, but

most of its work is associated with product testing to ensure

conformance with fire test standards.

EDUCATION

Society of Fire Protection Engineers (SFPE)

SFPE, although smaller than the professional societies of the

major engineering disciplines such as civil, mechanical and

electrical, has similar goals and objectives. It has forty local

chapters in the United States, Canada and Europe. Technical

meetings and symposia are held at local and chapter levels, and

the society publishes a limited number of technical reports and

symposia proceedings. A most significant event in SFPE's history

occurred in 1981 when it started to administer the fire

protection engineering-professional Engineer (PE) registration

examination

The United States Fire Administration (USFA)

The USFA, which is part of the Federal Emergency Management

Agency (FEMA), is located at Emmitsburg, MD about 70 miles north

of Washington, DC. It has a staff of less than 20 professionals

but manages a 9 million dollar program of contracts and grants to

others. The program includes promotion of residential

sprinklers, public education and awareness, firefighter health

and safety studies, data collection and analysis, fire service

management studies and arson prevention studies.

The National Fire Academy

The National Fire Academy, is an organizational part of FEMA's

activities in training and education. Also located at

Emmitsburg, it is a residential training center providing

advanced training to fire service personnel. The programs

offered usually last two or three weeks and range from executive

fire officer development and fire service management to Line

officer training.

Universities

The University of Maryland, a large State university with a total

student population of nearly forty thousand, is the only college

60
i n< the United States currently offering a four year program

leading to a bachelors degree in fire protection engineering.

About 30 students graduate each year, most finding jobs with

private industry fire protection engineering consultants,

government agencies or insurance companies.

Worcester Polytechnic Institute (WPI), a private college located

near Boston, is the only college in the U.S. that runs a formal

master's degree program in fire protection engineering. Students

in this program at WPI typically have a prior bachelors degree in

an engineering discipline. In addition many colleges offer 2 year or 4 year degrees in fire science, fire technology or fire

administration

CONCLUDING REMARKS

As can be seen from the above descriptions, fire protection

organizations in the United States vary widely in size, anatomy

and funding. There is no overall coordination of these

activities, and yet each performs its functions well without

major attempts to eclipse those of the others. The fire record

of the United States is not as good as those of many other

developed nations for various reasons, so each of the above

organizations needs to make maximum use of its resources to do

its share in reducing the toll of life and property loss in

unwant ed fires.

BIBLIOGRAPHY

1Yearbook and Committee List 1985. National Fire

Association, Quincy, MA.

Protection

2. 1985 Annual Book of ASTM Standards.

Testing and Materials, Philadelphia,

American Society

PA.

o f

3 . Society of Fire Protection Engineers

Society of Fire Protection Engineers,

Yearbook.

Boston, MA

Sept.

• 198 5 ,

4 . The 1983 Fire Almanac. National Fire

Quincy, MA.

Pro tec tion Association

5. National Fire Academy Course Catalog 1985-1986.

National Emergency Training Center, Washington,

FEMA

DC .

6 . Clarke, F. G. , ASTM Committee E5: An

Standardization News, Vol. 9, No. 12,

Overview, ASTM

pp . 9-13, Dec

198 1.

61
• .. • ‘ 1

.

62
Industrial Fire Suppression

Andrew J. Fowell

Chief, Fire Safety Technology Division

Center for Fire Research

National Bureau of Standards

Gaithersburg, MD

Introduction

Fire protection of industrial facilities involves four different but

mutually compatible approaches, namely, the use of non-combustible materials

for construction, compartmentation, automatic suppression systems, and smoke

control and removal systems. The first two are passive the others are activated after detection of the fire. Of the four, only automatic suppression systems are designed to put out the fire, the others merely control the

extent of the fire until the fire brigade arrives. This paper focuses on automatic sprinkler systems, their design, performance, application and

testing. Brief reference is made to other suppression systems using foam and

halon extinguishing agents.

Design

The primary features of a sprinkler system are the water supply, which

may be fed by gravity, stored pressure, or a pump, a fire main and a series of

sprinkler networks. Each sprinkler network consists of a supply pipe, a stop

valve, an alarm valve, and a series of distribution pipes at ceiling level on which the sprinkler heads are mounted. General design of the piping system

can be done using sets of tables ("pipe schedules”) or by hydraulic calculation. Computer programs are available to perform these somewhat tedious

calculations. Sprinkler heads themselves have three essential parts, namely a nozzle, a releasing device, and a deflector. The most common form of

releasing device in the United States is a soldered link element which opens

the nozzle when the solder reaches its melting point. Other types include a glass bulb containing a liquid that expands when heated and bursts the bulb,

and a low - fusing chemical that liquifies at the rated temperature and allows

the strut holding the valve closed to collapse.

Standard sprinklers can be upright or pendent. Upright sprinklers, which

are mounted above the supply pipe are marked "Upright-SSU" , and pendent

sprinklers, which are mounted below the pipe, are marked ’’Pendent-SSP" . The

main disadvantage of pendent sprinklers is that the piping cannot be drained

quickly when freezing is anticipated. Other types of heads include flush type

which are mounted in the pendent position but flush with the ceiling to

improve appearance, and sidewall type which are equipped with a special

deflector so that most of the water Is discharged away from the wall against

which the sprinkler is mounted. Sidewall sprinklers have become popular

because they are generally easier to install in retrofit situations.

For industrial applications both closed pipe and deluge (open pipe)

systems are used. The closed systems either contain water under pressure (wet

pipe system) or in unheated buildings in' climates where freezing is possible,

air under pressure (dry pipe system). In both wet pipe and dry pipe systems

63
water flows only from the sprinkler heads that are activated by the fire. The

deluge system has open sprinklers and is used when it is desirable to wet down

the whole of the protected area. The water supply is held back by a deluge

valve which is actuated by a system of heat responsive sensing devices

throughout the protected area. A variation of the closed system is the prereact ive system where the water is held back by an automatic control valve

which, like the deluge system, is actuated by a system of heat responsive

devices. This precharges the system but the water discharges only when the

sprinkler heads themselves open.

Performance

The performance of a sprinkler systems depends on many factors including:

1. The actual operating temperature of the device

2. The thermal capacity of the link material

3. The heat transfer from the air to the sprinkler

4. The rate of growth of the fire

5. The height of the ceiling

6. The shape of the ceiling

7. The thermal qualities of the ceiling

8. The distance between the sprinkler and the ceiling

9. The horizontal distance between the sprinkler and the fire

10.

Factors that will effect the flow of gases from the fire to the

sprinkler

Sprinklers are available with normal operating temperatures ranging from 57°C

to 260°C. Soldered link sprinklers generally have less variation from the

nominal operating temperature than the glass bulb type.

The thermal capacity of the sensing element controls how quickly the

sprinkler will actuate when immersed in hot gas. The higher the thermal

capacity the slower the response. The trend in the United States is toward

"fast response" sprinklers. The speed of response of a sprinkler can be

identified by a "Response Time Index" which ranges from 100-400 ml/2 3 l/2 f or standard sprinklers to 25-50 m^/2s l/2 f or f as t response units.

The slower the response of the sprinkler the larger a growing fire can become by the time the sprinkler activates. Hot gases from a fire fill a room from the ceiling down so other than immediately above the fire the greater the

distance between the ceiling and the sprinkler the slower the response.

Obviously the shape and thermal properties of the ceiling and the ventilation

patterns also effect the temperature rise at the sprinkler.

Sprinkler systems have in general been reliable and very effective. The

primary reason for system failures has been shut off supply valves.

Application

The general rules governing the installation of sprinklers in the United

States of America are laid out in the National Fire Protection Association

Standard 13. The primary factors affecting the location and spacing of

sprinklers are the type of occupancy, i.e. ordinary hazard or extra hazard,

and the type of construction. It would be impossible to cover here all the

64
details contained in NFPA 13 but some special cases may be of interest. In

high rise buildings for instance, the performance of sprinkler systems in

protecting life has been well documented. Most high rise buildings are used

for offices, hotels and residences and as such are classified as ordinary

hazard. Extra hazard occupancies include commercial and industrial locations

where the fire load is high, i.e. the materials handled, stored or processed

are highly flammable such as volatile liquids, wood and cotton, or stored in

high rack storage. Some typical locations classified as extra hazard

occupancies are aircraft hangers, wood working shops, plastic, foamed rubber,

paint and firework manufacturers.

Substantial research is underway to improve protection for high rack

storage in warehouses, with in-rack sprinkler systems receiving much

attention. NFPA standard 13 covers goods stored up to 4m high and NFPA

standard 231 deals with storage up to 7.5m high.

Testing

All sprinkler systems should be tested after installation and an inspection report completed. It is important to flush outside underground

piping under pressure before connections are made to sprinkler risers. This

is to remove stones or other material which may have entered when the pipes

were laid.

A hydrostatic leak test should be performed on the system. The test

pressure of 200 lb/in^ (or 50 lb/in^ above line pressure if the line pressure

is above 150 lb/in^) should be maintained for 2 hours. The pressure should be

maintained with a small pump with the main shut off valve kept shut so that if

a leak or burst occurs any water damage will be minimal. Dry pipe systems

should have the differential valve latched in the open position. In addition

to the hydraulic test, dry-pipe systems should be tested with air at a pressure of 40 lb/in^ for 24 hours. Any leakage of more than 1 1/2 lb/in^ in

the 24 hours should be corrected.

Deluge and prereaction systems should be tested with a heat source to

ensure that all the components (heat responsive devices, alarms, and the

deluge valve clapper) are operational.

Finally, a precautionary word concerning maintenance. Whenever

sprinklers are shut off for maintenance or repairs a serious protection

emergency exists and special procedures should be followed:

1. Work should be scheduled on weekends or idle periods

2. Shut off the least number of sprinklers possible at a time

3. Have tools and materials ready before starting so the shut off time can be kept to a minimum

4. Notify the local fire department

5. Lay out charged hose lines from the nearest fire hydrants and have

portable extinguishers available.

6. Tag the shut off valve and establish a follow up procedure to ensure

the valve is reopened on completion of the work.

7. Do not leave sprinklers shut off overnight

8. Have the area continuously patrolled

65
Other Fire Suppression Systems

For protection of high hazard areas such as aircraft hangers and

petrochemical areas fixed foam-water spray systems are used. The systems are similar to regular water sprinkler systems except that the sprinkler nozzles

are replaced with aspirating nozzles which produce foam when supplied with an aqueous film forming foam solution (AFFF) . Obviously the systems include

concentrated tanks, proportioners , and pumps. Detailed design requirements

are contained in NFPA Standard 16.

Fixed carbon dioxide extinguishing systems are sometimes used for

flammable liquid fires, electrical fires and for protection of rooms containing high value contents such as record vaults and computer rooms.

Halogenated systems are also used for protection of high value contents

such as computer rooms. Different halons with differing properties are avail

able. The designation, eg. halon 1301, identifies the number of carbon,

fluorine, chlorine and bromine atoms respectively in each molecule. Halons

are expensive and are generally used to protect small areas only. Recently

concern has been expressed over the corrosive properties of the combustion

products of halons when used with computer installations. Studies are underway to investigate these concerns.

Industrial fire suppression systems installed according to published

standards have proved to be reliable and effective in controlling fires and

reducing losses. However, research into fire suppression and sprinkler system

design for special applications is continuing in the United States at both the

Factory Mutual Research Corporation and the Center for Fire Research at the

National Bureau of Standards, and into other suppression systems by the U. S.

military and various manufacturers.

Bibliography

1. Factory Mutual, Handbook of Industrial Loss Prevention. McGraw-Hill,

1959.

2. Nash P. and Young, R.A., Automatic Sprinkler Systems for Fire Protection.

Victor Green Publication, 1978.

3. NFPA No. 13. Standards for the Installation of Sprinkler Systems,

National Fire Protection Association, Boston, MA , USA.

4. NFPA No. 13A. Recommended Practice for the Care and Maintenance of

Sprinkler Systems, National Fire Protection Association, Boston, MA, USA.

5. NFPA No. 231. Standard For Indoor General Storage, National Fire

Protection Association, Boston, MA, USA.

6. NFPA Fire Protection Handbook, National Fire Protection Association,

Boston, MA, USA.

7. NFPA No. 16 Standard for Foam-Water Sprinkler and Spray Systems.

8. NFPA No. 12A Standard for Halogenated Extinguishing Agent Systems.

6 6
NBS-114A 'REV. 2 -80

U.S. DEPT. OP COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions

)

1. PUBLICATION OR

REPORT NO.

NBSXR 86-3360

2. Performing Organ. Report No. 3. Publication Date April 1986

4. TITLE AND SUBTITLE

A Record of the papers to be presented at the Workshop on Fire Protection

Technology to be held in Cairo, Egypt, April 27 and 28, 1986.

5. author(S) Kurt F. J. Heinrich, Irwin A. Benjamin, Richard W. Bukowski, Richard L.P

Custer, and Andrew J. Fowell

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions)

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 26234

7, Centracfc/Grant No.

I. Type of Report & Period Covered

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

Agency for International Development

Department of State, Washington, D. C. 20523

10. SUPPLEMENTARY NOTES

! | 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)

A series of talks were given by the U.S. participants in the Workshop on Fire Protection Technology, within the framework of the cooperation of NBS

with Egyptian institutions. The Egyptian institution involved with this

workshop is the National Institute for Standards. NBS proposed the Workshop

in order to explain the value of fire safety to the intended audience.

12. KEY WORDS (Si* to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) AID, Fire Detection, Fire Organizations, Fire Safety, Fire Statistics,

Industrial Fire Supression, Investigations

13. AVAILABILITY

; j Unlimited For Official Distribution. Do Not Release to NTIS

1 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

70

15. Price

USCOmm-OC A043-P 80
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