Methods of Testing Small Fire Extinguishers

United States Department of Commerce

National Bureau of Standards

Building Materials and Structures Report 150
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UNITED STATES DEPARTMENT OF COMMERCE • Sinclair Weeks, Secretary NATIONAL BUREAU OF STANDARDS • A. V. Astin, Diuclor

Methods of Testing Small Fire Extinguishers

H. Shoub, T. G. Lee, and J. M. Cameron

Building Materials and Structures Report 150

Issued June 14, 1957

For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price 15 cents
Contents

Page

1 . Introduction 1

2. Description of test extinguishers and agents 1 3. Description of test methods 2

4. Kesults 5

5. Discussion of I’esults 7

6. Conclusions 9

II
Methods of Testing Small Fire Extinguishers

H. Shoub, T. G. Lee, and J. M. Cameron

A study has been made of methods of testing small hand-portalde fire extinguishers

considered suitable for application to flammable liquids. The study was performed by

evaluating the eftectiveness of the extinguishers, in which 5 different extinguishing

agents were used on 10 types of tires, selected either because they had been used in stand- ard extinguisher tests or simulated other possible conditions of hazard. An analysis was made of the relative merit of the fires for extinguisher testing, the effect of ambient vari- ables on the tests, and the value of the several extinguisher types for use on the fires.

1. Introduction

Although several types of small hand-portable

fire extinguishers have been available for combatting fires of flammable liquids, the relative effi- ciency of these devices has been little understood.

The continuing work of the National Bureau of

Standards has led inevitabh^ to the conclusion that

wide variations in performance were obtained

with these devices. To determine a means for

measuring the extent of these variations, a program of tests was undertaken under the sponsorship of the U. S. Coast Guard. A^diile the primary

purpose was to establish some standard of suitability of extinguishers for use on small motorcraft. it is considered that the work was of

sufficiently broad aspect to allow extension of the

applicability of the findings to many types of

small flammable liquid fires. In planning the tests, the program was en- visaged in several parts. A group of fire extinguishers was selected to apply the extinguishing

agents used in the study. Each device was representative of its type and class, and individually

without defects that could impair its performance.

A series of suitable fires were selected or devised.

These included several types of test fires used by

commercial testing agencies and the National

Bureau of Standards. Additional types, making

for a total of 10. Avere based on preliminary designs of the Merchant Marine Technical and Test- ing and Development Divisions of the Coast

Guard. Finally, the effect of ambient variables on the tests was noted. Statistical methods were

used in planning the tests and in analyzing the

large body of data resulting from the program.

2. Description of Test Extinguishers

and Agents

Fifteen extinguishers, all readily obtainable

commercial makes, were chosen for the purpo.ses of these tests. Each carried the Underwriters’

Laboratories, Inc. B-2 rating. Among these were

devices using all common types of extinguishing

agents suitable for flammable-liquid fires, and

further varied in capacity, and in rate, duration,

420335—57

range, and continiuty of discharge. At the end of

the program no wear or damage to the devices

sufficient to affect their operating efficiency in any

Avay was found. The extinguishers used are listed

in table 1. The extinguisliers used may be classified into

4 groups according to the type of agent employed

A'aporizing liquid, carbon dioxide, dry chemical,

and foam. Of the 8 devices using vaporizing

liquid, 7 were charged with carbon tetrachloride

extinguisher fluid and 1 with chlorobromomethane. Of these, 4 were hand piunps; the

remainder depended on gas pressure stored in

the charge chamber to give the necessary expelling force. The carbon tetrachloride was supplied

under the requirements of the Federal specification for this material. The single chlorobromomethane device was charged with fluid stated to comply with U. S. Air Force requirements. Two

of the hand-pump extinguishers had a slightly

intermittent action, and were the only ones in

which the discharge rate was iinder the control

of the operator. Because of differences in the

mechanism, two of each size of hand-pump carbon

tetrachloricle extinguishers were included.

The three carbon dioxide type extinguishei-s

each had different capacities: 2^/2 , 5. and 10 lb. They were charged from standard CO, cylindei-s.

The gas pressure in a fully charged deA'ice of any

size is about 850 Ib/in^ at 70°F. Approximately

75 percent by weight of the dischai’ge is effective

for fire extinguishment.

Two of the three extinguishers in the drychemical group were of the stored-pressure type,

and consisted of 4- and 5-lb devices. The third

had its expelling gas in the form of a cartridge,

and Avas of 4-lb capacity. Although all the dry

chemicals consisted of finely ground bicarbonate

of soda treated Avith a Avater repellent, only material manufactured for the particular extinguisher Avas used in each case. A single extinguisher Avas of the foam type. Ir had capacity, and Avas the only device of

the 15 tested that Avas rated for use on ordinary

combustible materials, as Avell as on flammable

liquids. Also, it AA'as not suited for electrical tires, for AA'hich the other 14 extinguishers of the pro1
Table 1. Extinguishers used in the iire tests

Extinguisher Agent Type Range

Approximate

discharge duration

1 Vaporizing liquid: Hand pump

ft 20

sec

2 . do 20 50 to 60

3 Stored pressure..- _ 20 to 25 22

4 . .do 20 to 25 22

5 Hand pump ..... 20 50

6 .. .do 20 90 Stored pressure 20 to 25 22

8 2 qt of ecu. - - .do ... - - 20 to 25 36

9 Carbon dioxide: 2mh Quick-opening valve... 4 16

10 51b .. do.- - 6 25

11 10 lb .do . 8 43

12 Dry chemical:4 lb Cartridge-tvpe.. . 5 to 15 11 13 4 lb Stored pressure 13

14 5 lb do ... .. 2 to 10 17 Foam: IH ?al Used with commercial packaged charge 30 to 35 40

gram were acceptable. The discharge, once initi- ated, could not be terminated before total exhaustion. Commercial foam materials, which

had been previously found to give consistently

good performance, were used for the charge.

]\Ianufacturers’ charging instructions were fol- lowed closely. In most cases charges were established on a weight basis, Avitli a tolerance of ±0.05

lb. However, to provide a space of constant vol- ume for the gas in stored pressure vaporizing

liquid and dry chemical extinguishers, the charge

weight in these devices was regulated to 0.01 lb. In order to minimize the intake of moisture into

stored pressure extinguishers, which might adversely affect the charge in dry chemical devices or cause deterioration of the working parts of

vaporizing liquid models, oil-pumped nitrogen was iTsecl as the expelling gas. Discharge rate curves, determined empirically

for extinguishers at approximately 70°F, are shown in figure 1. Rates for hand-pump carbon

tetrachloride extinguishers were based on average

performance, using a pumping rate of approximately one full cycle per second.

Figure 1. Approximate discharge rates of test extin- guishers.

3. Description of Test Methods ^ The three types of fires that have served as standard tests of small extinguishers for flam- ! mable liquids are the 4-ft-square spill area, a cotton-waste fire, and a nominal 2-ft-diameter tub.

Four types were representative of fires in partially

enclosed spaces, with or without an obstacle to free

dispersal of the extinguishing agent. The en- closed space was sinndated by a metal compart- I ment in which changes in the opening could be

effected by removal in whole or part of the end

plates and top. The design of three of these types ! of fires was such that the fuel consumption rates were maintained at approximately the same level. The components of the compartment, as well as the pan used both alone and as the fuel container ' in the enclosed space, are shown in figure 2. The

construction of the parts is shown in figure 3. ! In addition, three other types of possible hazard ' were simulated. These included an open, shallow

pan, a leaking container, and a spill flowing over j a wide vertical surface.

As the extinguishers were intended primarily i for flammable-liquid fires, the structures used in

the several fire configurations wex’e of noncombustible materials, although in certain tests a meas- ured amoimt of an ordinary combustible, wood, ,

Figure 2. Campartment components, pan, and wood

grating.

2
450

Figure 3. Compartment and obstacle.

Both units made from 2-in. by 2-in. by %-in. angle and 14 gage

steel plate fastened with %-in. bolts,

a. Compartment made with bottom open, long sides covered, top and end plates removable : b, obstacle covered on all sides.

was introduced as a means of determining the

effectiveness of the extinguishers on mixed

fires. The fuel used in all but one of the tests was a conmiercial mixture of heptanes having

a narrow distillation range at approximately

200° F. This fuel, rather than gasoline, was used

in order to create reproducible conditions of fuel

consumption throughout the program, as well as to provide fair burning equilibrium during the course of a single trial. The distillation curves

for the test fuel and the average of a number of

gasolines are shown in figure 4.^ The properties

of gasoline are known to fluctuate seasonally, and

vary with the producer and point of origin. Gasoline, also, because of its wide volatile range, exhibits marked differences in characteristics during

the burning of a specimen, with rapid consumption of the more volatile portion and ending in

progressively slower consumption of heavy fractions. Radiant-energy measurements for several

gasolines and the heptane mixture were approxi-

^ O. C. Blade, Bureau of Mines, Dept. Interior, National Motor

Gasoline Survey of Summer 1954, Report of Investigation 5111 (January 1955).

Figure 4. Distillation curves of fjasolines and test fuel.

Gasoline curve represents average of 350 regulars tested midAtlantic States, summer, 1954.

mately the same. In duplicate tests, made with the

two fuel types, no appreciable differences were

noted in extinguisher performance that coidd be

attributed to the type of fuel used. To introduce

the effect of another type of fuel, an exception was made in the case of the vertically flowing spill

fire, in which alcohol was used.

Fuel-consumption rates were determined from

time to time during the program to check the consistency of the tests. However, it was noted that

changes in ambient conditions, which ranged from

calm to moderately liigh wind and from 32° to 85°

F, had little significant effect on the fuel consumption. Each of the test fires is described, with pertinent

data, in table 2. The pan used in fires VI through

X had dimensions of 4 by 24 by 48 in. The fuel

in the pan, as well as in the 2-ft tub, was poured

over approximately 1 in. of water. The four types

of wood gratings used ou the pan to control the

burning rate, as well as to add a fuel complication, are shown in figure 5. The arrangement of

openings in the compartment for fire types VII to X are shown in figure 6. In the progTam, a test of each of the 15 ex- tinguishers on the 10 types of fires, deflned heiv

as a series, was repeated 5 times to provide sutli- cient data for a signiflcunt statistical analysis of

the results. The experiment was programed so that the iutercomparisou among extiuguishei-s

would not be affected by ditl'ei-ences in weather

conditions or other factors changing with time.

Generali}", it was possible to coiuluct tests of all 15 extinguishers ou a single type of liiv in a day.

The schedule was so arranged that each day's ojH'r-
Table 2. The 10 test fires

Fire model number

Description Fuel Preburn time Fuel-consumption rate

T gal % heptane. .

sec

5 “mf/scc Approx. 40. IT H heptane . - 10 TIT _do - 20 Approx. 10.5. 14 to 10 (0 to 60 sec).

11. 5. IV ^4 heptane. 20 (after 10-sec flow). - . V 1 ethyl alcohol 30 (after 10-sec flow) VI 1 heptane 60- 15±1. VII

VIII Compartment, top open; pan and wood grating A

Compartment, top and 2 lower ends open; pan and wood

do - do

60

60 12±1.17. 8±. 7. IX

grating B. Compartment, top and 1 end open; pan and wood grating do 60 19. 2±.7. X Compartment, 1 end and adjacent 4 in. at top open; pan and wood grating D

do . 60 18±1. 2.

« 1 ml = 0.000264 gal.

ation was divided into 5 time periods of 3 extin^iisliers each. In the course of the pi'ogram,

all 15 extingidshei’s were used in each of the time

periods on each fire. While comparatively experienced operators were used, the results were nevertheless influenced

by the operators’ techniques and to some extent by experience acquired in the tests. In an effort

to simulate actual conditions as nearly as possible, no special protective equipment was provided the operators. In attacking- fii-es, the approach was as close as that allowed by the intensity of the radiant heat, or as near as that requii ed

for the apparent optimum use of the extinguishers.

The data taken during each test included vari- ous observations of weather conditions, such as temperature, wind velocity and direction, barometric pressure, and humidity. Temperatures of

the fuel and the extinguishers, the latter maintained at approximately 70° F, were noted. The

method of attack and the amount of extinguishingagent expended were also recorded.

XD \ZL II II II II

I I I I I I rr

TD U U FT

c 3^

I] Q.

I] [J

D

SECTION A

An attempt was made to take into considera- j tion essential information that would be lost if i-ating were simply on the basis of percentage of

success or failure. This was done by assigning

a score to each trial. An arbitrary rating system i was established, based on six levels of success, ranging from -f3 to —3, with the plus scores as- signed to cases in which the fire was extinguished, j highest number for easiest accomplishment, ancl j minus numbers for failures, —3 representing the f case of least effectiveness. Generally, the plus ratiiTgs were based on the unexpended amount of ex- i tingnishing agent. Because in cases of failure

the charge was completely spent, minus ratings i ranging from — 1, almost extinguished, to — 3, no ! apparent attenuation, were assigned on the basis I of the operators’ judgment. f

Figure 5. Wood gratings.

Gratings are constructed of Ponderosa pine, No. 2. common,

nominal 1-in. by 4-in. mill lumber (dressed dimensions in. by 3% in.).

Figure 6. Arrangement of compartment openings for t extinguisher tests.

|!

Fuel pan, wood grating, and obstacle not shown. 4
I 4. Results

I The perfoi-mance ratings of the 5 trials of each

I of the 15 extinguishei-s on the 10 types of fires, 750 tests in all, are shown graphically in figure 7.

1 Considering the 150 group results solely on the

,j basis of success or failure in extinguishment, 94

I showed complete agreement in the 5 rims, 30 had 1

j disagreement, with the remaining 2G marked by a

; 3-and-2 split.

I In the data for the 4- by 4- ft. spill fire (No. I),

{ a dotted-circle designation indicates those cases in

I which extinguishment was accomplished aftei- the

' fire area was considerably reduced from its orig-

! inal size. It was observed that this occurred in

about 30 sec. Thus devices requiring more than

I this time to effect extinguishment are not compaj rable to those actually successful against the fullI sized fire. For statistical purposes in ranking exj tinguishei-s, the dotted-circle designation was asI signed a rating of +1.

I The saturated cotton-waste fire (No. II) was

1 characterized by nonuniformity of fire source durI ing the extinguishment period as all or most of

j the liquid fuel was exhausted after about 60 sec

j of burning. This left a slow-burning-cotton fire

j not representative of a flammable-liquid hazard.

Although in many cases there was momentary' ex- tinction of the flames by the time the extinguisher

charge was exhausted, reignition usually occurred

in the large body of glowing and smoldering

mateiial. In assigning performance ratings on

this fire, results were considered successful if reignition did not occur within 5 min.

Table 3 gives the sums of the scores obtained on

each of the 5 separate trials on the different test

fires. A tabulation of the number of times each

extinguisher succeeded in putting out the 10 fires

is given in table 4. In table 5 the data show the

differences between series. Each entry represents

the number of successes of a given extinguisher

summed over all fires in a series. A significant

effect here is the fact that series 1 shows fewer

successes than the remaining 4 series. The or- der of listing in tables 4 and 5 is roughly that of

relative effectiveness achieved with the devices, but

is also determined by grouping according to ex- tinguisher type. Using the same arrangement,

the relative rankings of the performance of the 15

devices, based on several methods of comparison,

are presented in table 6. All methods of per- formance measurement give essentially the same

rankings. Reasons for the omission of fire No.

II in tables 4 and 6 are given in the following dis- cussion.

I

I KEY

EXTINGUISHED ©+3

@-»-2

NOT EXTINGUISHED

o — I 0-2 EXTINGUISHMENT OCCURRED AFTER FUEL AREA DIMINISHED

Figure 7. Performance obtained with extinguishers on test fires^
Table 3. Su7n of scores obtained with the 15 extinguishers on each of the 10 fire types (sum of 5 runs)

Extinguisher

FIRE MODEL NUMBER

I II III IV V VI VII VIII IX X

1 ... . -8 -12 -1 -15 -15 -13 -11 -13 -15 -8

2 -4 -13 -3 -14 -15 — 15 -14 -15 -15 -9

3 . - -10 -10 14 -10 -1 -10 1 -14 -12 -1

4 -- - 10 -1 15 12 15 11 14 0 9 14 5 2 -8 7 -10 -10 -10 -7 -13 -11 -4

6 5 -3 -12 -13 -14 -14 -14 -12 -14 -12 -1 13 1 9 —7 12 -10 -2 10 8 5 2 14 3 9 -4 8 -10 -2 12

9 -3 -14 13 -12 7 -3 -3 -14 -4 5 10 1 2 14 -9 9 9 4 2 2 5

11 11 4 15 4 14 14 15 10 11 13

12.. 13 -8 14 11 14 11 12 10 8 14

13 14 -7 15 11 12 10 11 6 4 8

14 .. 13 -9 15 4 13 13 0 8 14

15... 3 5 15 -3 12 0 -9 -2 -1 4

Totals - . - +51 -78 +148 -40 +59 -14 +32 -79 -34 +65

Table 4. 'Number of successes with each extinguisher in five trials on each fire type

Extinguisher FIRE MODEL NUMBER Total numberTotal number

in 50 in 45 No. Agent I II III IV V VI VII VIII IX X trials trials “

2 CCh 2 0 1 0 0 0 0 0 0 1 4 4

1 cell 1 0

9 0 0 0 0 0 0 1 4 4

6 cell 5 2 0 0 0 0 0 0 0 0 5

5 cell.... 4 0 4 0 0 0 1 0 0 1 10 10

3 cell 0 0 5 0 2 0 2 0 0 3 12 12

7 cell .. 2 1 3 5 0 5 0 2 28 27

8 cell 5 3 3 5 1 4 0 3 4 33 30 Foam 4 4 5 1 5 9 0 2 2 4 29 25

9 CO2 - 2 0 5 0 4 1 2 0 2 4 20 20

10 co-.._. 2 4 5 0 4 4 4 2

9 5 32 28

11 C02 5 4 5 3 5 5 4 5 42

14 5 0 5 3 5 4 2 4 5 38 38

13 . do. 5 0 5 5 5 5 5 4 4 43 43

12.. 5 0 5 5 5 5 5 4 44 44

4 Chlorobromomethane- . 5 2 5 5 5 5 5 2 5 5 44 42

Totals . 52 20 62 28 50 32 43 21 33 53 394 374

“ Omitting fire No. II.

Table 5. Total ntiniber of successes with each extinguisher on all 10 fire types in each of the 5 series

Extinguisher

Series Total for

5 Series

1 2 3 4 5

2 0 1 1 0 2 4

1 0 2 0 2 0 4

6 _ 1 1 1 2 2 7

5._ 1 2 4 1 2 10

3 2 2 2 3 3 12

7 4 4 7 7 6 28

8 4 7 7 8 7 33

15 3 5 5 7 9 29

9.. 4 3 5 5 3 20

10 5 7 8 6 6 32

11 9 10 9 9 9 46

14 7 7 8 8 8 38

13 7 9 9 9 9 43

12 9 3 9 9 9 44

4 8 9 9 9 9 44 Totals, 64 77 84 85 84 394

6
I Table 6. Performance obtained with test extinguishers

Eitinguisher Agent and amount

2 I ecu, 1 qt...

1 1 ecu, 1 qt...

6 ecu, lj’2 qt, 5 ecu, Ih qt.

3 ecu, Iqt,,, ecu, l!.2at_ ecu, 2 qt...

15 Foam, U4 gal.

9 : C02,2H lb10

i CO2, 5Ib...

11

i CO2, 10 lb..

14 Dr}' chem., 5 lb13 Dry chem., 4 lb12 I Dry chem., 4 lb.

4

1 Chlorobromomethane, 1 qt.

Type

Hand pump.

dodo

do

Pressurized. do

do

Stored pressure.

-do. Cartridge

Stored pressure.

A

Percentage of success

-

Percent- age of success, omitting

fire II

C

Average

scores

D

Average

scores, omitting

fire II

Ranking according to

A B C D

8 9 -2.3 -2.3 1. 5 1.5 1 , 8 9 -2.2 -2.2 1.

1.2 3

14 11 -2,

-2.2 3 3 3 2 20 22 -1,3 -1,2 4 4 4 4

24 27 -1.

-1.0 5 5 5 5

56 60 0.4 0.6 7 8 7 8 66 67 .7 .8 10 10 10 10

58 56 .4 8 7 8

_

40 4-1 -.6 -.3 6 6 6 6

64 62 .7 7 9 9 0 9

92 93 2.2 2.5 15 12.5 15 15

76 84 1.6 2,0 11 11 11 11.5 86 96 1.7 2.0 12 14 12 11.5 88 98 2.0 2.4 13.5 15 13.5 14

88 93 2.0 2.2 13.5 12.5 13.5 13

j

5. Discussion of Results

; In considering the 91 groups of consistent rei suits where either extinguishment or failure oci curred in all five trials of a device on a particular

fire, it may be assumed that the performance efl'ecI tiveness of these extinguishers was such that varia-

! tions in weather conditions and operator skill dur -

j ing any of the five nms was not sufficiently great as

! to change the outcome. The relative success or

I failiu’e scorings within a group, however, were

affected by these variables.

Almost uniform success was possible in fighting

fires with some extinguishers, whereas with some

others there was equally consistent noneffectiveness. Also, the application of a certain extinguisher may have been a success against a minor

fire on every trial, yet may have resulted in com-

; plete failure on a more severe type of hazard,

j The performance obtained with such a device on

] a fire of intermediate severity frequently resulted

I in neither all success nor all failure ; success could

j depend on the right combination of environmental

I conditions and operator technique. If trials of an

i extinguisher showed a low percentage of success

I against a particular fire, these successes must have

I been achieved under a very restrictive set of con-

! ditions. On the other hand, a device with which

a high percentage of success was achieved could be

said to be less sensitive to minor deviations from

optimum operating conditions. In these tests, ex- tinguishers used in trials characterized by a large

number of nonuniform group results appear to be

high-sensitivity-type devices.

The fire configuration seems to be of considerable importance in the effectiveness of extinguishment. The poorer performance obtained with

carbon tetrachloride type extinguishei*s on fire VI

than on VII may be attributed to the lack of confining surfaces on the shallow-pan fire. This

causes a reduction in the volume of decomposition

products, which are best produced by vaporization

against a hot surface. Also, there is no means of

preventing the rapid dissipation of the volatile

gases that are formed. A specialized method of

attack with carbon tetrachloride is illustrated by

fire lA", in which fuel is fed through a small opening. By dii'ecting the stream of vaporizing liquid

directly at the source, the fuel could sometimes

be diluted to a point at winch it no longer sustained

combustion.

In fire models A"III, IX and X, where the fuel

consumption rates throughout the proeri’ani were

approximately equal (18.5 ±1.1 ml/sec), confinement was apparently the primary factor affecting

extinguisher performance. The test devices

showed significantly greater effectiveness on a fire model such as No. X, in which the highly confined

configuration tended to accumulate the agent to a concentration level necessary for extinguishment.

Accumulation of vaporizing agent, however,

may not be the onl}’ explanation for this apparent

correlation between degree of confinement of fire models and effectiveness of extinguishment. The

relation of the agent to the tlammable limirs of the

fuel, which for heptane range from O.S to 7 percent, may well be another factor. Even with a|>-

proximately equal fuel-consumption rates, the

three fires, AAII, IX and X, were not necessarily

burning at the same fuel oxygen ratio. It is pt>s- sible that in fire X the configuration is such that

air diffusion is restricted, especially as eompaivd

with No. ATIl, with the apparent ix'sult that the

fuel mixture was cousideraldy richer than in other

fires. On the basis of llammability limit tests, it has beeit suggested tluit the \olume of va^mrizing

liquids (and perhaps other agents! ivquiivd for

siu'h a fire is much less than that for tiivs having
a lean mixtiu’e caused by an excess of available

air.^In conducting the tests, it was found that optiimun methods of attack varied with the fire model

and particularly with the extinguishers. Generally, carbon tetrachloride was best employed by

spraying on a hot surface to secure maximum

vaporization, and in such manner as to cover the

area with the decomposition products. Dry chemical extinguishers were most effective when operated to cover the whole flaming area at once. Carbon dioxide types seemed to work best when the

agent was discharged in a sweeping motion neai- the fuel surface. Foam was effective only if it could be flowed onto the burning-liquid surface;

its use was clifRcult in the presence of obstructions.

To secure results that would be impartial and unprejudiced, the operators in every case endeavored

to use an extinguisher to its maximum effectiveness. That this generally occurred is borne out by the fact that after increases from the first to third series, attributable to a learning effect, the

number of successes in the last three series of tests remained approximately constant. An inspection of the data of table 4 suggests

that Are II is not rei:)resentative of the same class of hazard as the other nine fires. It will be noted

that fire VIII has about the same low number of

successes, but it neveitheless ranks the extinguishers in essentially the same order as the remaining

fires. A discordant ranking is given by fire II, and for this reason further analysis has been car- ried out omitting this fire. This anomalous behavior is confirmed by a statistical analysis on

the data of table 4. Omitting fire II, the other nine fires can be

ranked in order of severity (most dithcult to ex- tinguish has rank 1) as follows

Fire

Percentage

of times Arc put out in 75 attempts Rank

Average

scores from 75 attempts Rank

VIII 26.7 1 -1.05 1 IV .37.3 2 -0. 53 2 VI 12.7 3 -.19 4 IX 44.0 4 -.45 3 VII 57.3 5 .43 5 V. 66.7 6 .79 7

I 69.3 7 .68 6 X 70.7 8 .86 8 Ill 82.6 9 1.97 9

While it would be convenient to have a measure on a continuous scale, such as the area of a given

type fire that could be put out, it is considered

that adequate screening of the effectiveness obtainable with the extinguishers can be achieved by use of several fires selected from those employed in

this progTam. From the results, it can be seen that

when fire III is not extinguished, the performance

= E. H. Coleman and G. W. Stark, A Comparison of the extinguishing efficiency of bromoehlorometliane and carbon

tetrachloride, Chemistry & Industry, p. 563 (1955).

is certainly weak in relation to the over-all per- I formance available with the extinguishers used in 1 this test. If trials are successful on fire III, perj formance could be further tested on an interme- ; diate fire, such as VII, and a difficult one, fire i VIII. I For practical purposes, a standard of perform- ; ance would have to be set. It is suggested that

extinguishment could be defined, for example, as

| success in putting out a particular test fire 4 times

in 5 trials, and further, to achieve an average score | as described herein of approximately +1 or

greater. It should be remembered, however, that

j even fire VIII, the most difficult test, does in no manner encompass the limit of possible hazards, j but rather defines the limit of extinguishing ' cajiacity obtainable with devices of a size and type

| considered in this program.

^ Although the fire-test program was conducted

outdoors under a wide variety of ambient conditions, the results based on scoring did not show an

appreciable influence of any individual measured

ambient factor, with the exception of wind speed. : What appears to be a significant day-to-day var

iation for some fires is actually almost entirely ! due to the increase in scores from the first to the ; subsequent series. ! Analysis of the data indicates that wind speed, i as a single variable, showed some statistically sig- : nificant effect on the scores of only a few types of • fires. The degree of wind sensitivity depended more on fire type than on ty]ie of extinguisher. [ Scores obtained on fires II, IV, and VI were ad

versely affected by increase in wind velocity,

whereas scores on fire VII seemed to be favorably

influenced by this condition. The rest of the fire

j models showed no significant trend in the scoiung. j The great number of cases of scores remaining'

nnchanged by the effects of ambient conditions is | considered to indicate the relative reproducibility

of the scoring system used.

As had been expected, a high rate of dischai’ge

[ in any particular type of extinguisher seemed to enhance the effectiveness of the performance. This

j is shown in an examination of the results of tests ! |j with hand-pump and stored-pressure-type carbon 1 1 tetrachloride devices, and also the 5-lb dry chem- I

ical extinguisher as against the two 4-lb models. J

Using the 15 extinguishers tested, trials withll

only three, the 10-lb carbon dioxide and the two 4- Ib dry chemical devices, met the suggested require-'

ments mentioned earlier for the most severe fire. No. VIII. Trials with the 1-qt chlorobromome

thane extinguisher narrowly missed the suggested

performance on this fire, but because of high effec- tiveness when used on the other fires, this device,;

stands with the other three extinguishers in a ; group with which the highest percentage of sue

cess for the whole program was attained. The 5-

lb dry chemical, 5-lb carbon dioxide, and IV2

- and : 2-qt stored-pressure carbon tetrachloride extin-,

guishers gave suitable results when used on an in-1 1 termediate fire such as No. VII. The suggested

8
minimum requirements would be obtained on fire III with the li/4 -gal foam extinguisher, the 2i/^-

! lb carbon dioxide, the 1-qt stored-pressure carbon

' tetrachloride and one of the hand-pump

carbon tetrachloride devices. The two 1-qt and

the remaining 1%-qt vaporizing-liquid hand

pumps were unsuited for use on even this minimum

fire, although it has been long considered a standard test for evaluating small extingiiishers of this

type. The results with these last extinguishers

have been corroborated by other investigators.®

In considering ease of handling of the several

types with which the most successful operation was

attained and the possibility of their successfid use by a novice, it is necessary to remark that the 10- lb carbon dioxide extinguisher, while effective, has

! a charge weight 21/2 times that of other devices in

its effectiveness group, and a total weight in excess of 3 times that of the next heaviest. This extin-

' guisher also has a relatively short discharge range,

forcing a close approach to the fire for effective use. The stored-pressure chlorobromomethane device

i| may be operated at a considerable distance (up to 20 ft) from a fire. The dry chemical extinguish-

‘

, ers are, however, the type most likely to lend themselves to effective use as their moderate-to-good

1 range and high accomplishment for their size are

i further augmented by the shielding effect that the

I powder affords against radiant heat.

I

! => T. B. Edwards, Army Fire Extinguishment Research Program

for Field Operation, Proc. Symposium on Fire Extinguishment

‘ Research and Engineering (U. S. Naval Civil Engineering ReI search and Evaluation Laboratory, Port Hueneme, Calif.,

' November 1954). Washixgton, November 16, 1956.

6. Conclusions

The following conclusions seem ju.stified on the

basis of the results of the test and the observations

made thereon

The test fires used for the study presented a useful scale for evaluation of extinguishing performance. From these, a group of three fires can be

selected to provide a qualitative means for measuring the performance obtainable with other devices

intended for use on flammable-liquid fires, esj>ecially those in hydrocarbon fuels. The rather large variations in ambient conditions observed during the test did not affect ex- tinguishing performance enough to cause statis- tically significant differences to appear in the re- sults for most fire types.

Erratic results obtained with some of the ex- tinguishers on certain fires could be ascribed to particular sensitivity of the extinguisher, perhaps

related to an unmeasured variable, to the conditions of the fire test, and to the technique of the

operator.

The apparent differences previously noted in the

effectiveness obtainable with various types and

sizes of extinguishers, all of which have sometimes

been equally rated for use on small flammableliquid fires, have been generally substantiated by

the results of the tests conducted in this program.

Extinguishers of the type of the 1-qt chlorobromomethane, 10-lb carbon dioxide, and 4-lb

dry chemical devices described herein ranked very

closely with each other as useful devices for attack on the test fires, and were superior to the other

types of extinguishers used in this program on

flammable-liquid fires of limited extent.

I

I

I

Q

0. 0. 00VCRNISNT rRIMTINi OFPWCi

BUILDING MATERIALS AND STRUCTURES REPORTS

[Continued from cover page ii] BMS37 Structural Properties of “Palisade Homes” Constructions for Walls, Partitions, and

Floors Sponsored by Palisade Homes * BMS38 Structural Properties of Two “Dunstone” Wall Constructions Sponsored by the W. E. Dunn Manufacturing Co 10^ BMS39 Structural Properties of a Wall Construction of “Pfeifer Units” Sponsored by the Wisconsin Units Co lOfi BMS40 Structural Properties of a Wall Construction of “Knap Concrete W'all Units” Sponsored

by Knap America, Inc BMS41 Effect of Heating and Cooling on the Permeability of Masonry Walls * BMS42 Structural Properties of Wood-Frame Wall and Partition Construction with “Celotex”

Insulating Boards Sponsored by The Celotex Corporation * BMS43 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 2 * BMS44 Surface Treatment of Steel Prior to Painting * BMS45 Air Infiltration Through Windows * BMS46 Structural Properties of “Scott-Bilt” Prefabricated Sheet-Steel Construction for Walls,

Floors, and Roofs Sponsored by The Globe-Wernicke Co * BMS47 Structural Properties of Prefabricated Wood-Frame Constructions for Walls, Partitions, and Floors Sponsored by American Houses, Inc * BMS48 Structural Properties of “Precision-Built” Frame Wall and Partition Constructions

Sponsored by the Homasote Co * BMS49 Metallic Roofing for Low-Cost House Construction 25^ BMS50 Stability of Fiber Building Boards as Determined by Accelerated Aging * BMS51 Structural Properties of “Tilecrete Type A” Floor Construction Sponsored by the

Tilecrete Co * BMS52 Effect of Celling Insulation Upon Summer Comfort 15^ BMS53 Structural Properties of a Masonry Wall Construction of “Munlock Dry Wall Brick”

Sponsored by the Munlock Engineering Co * BMS54 Effect of Soot on the Rating of an OU-Fired Heating Boiler * BMS55 Effects of Wetting and Drying on the Permeability of Masonry Walls * BMS56 A Survey of Humidities in Residences 10^ BMS57 Roofing in the United States—Results of a Questionnaire * BiMS58 Strength of Soft-Soldered Joints in Copper Tubing 15^ BMS59 Properties of Adhesives for Floor Coverings * BMS60 Strength, Absorption, and Resistance to Laboratory Freezing and Thawing of Building

Bricks Produced in the United States * BMS61 Structural Properties of Two Nonreinforced Monolithic Concrete Wall Constructions. * BMS62 Structural Properties of a Precast Joist Concrete Floor Construction Sponsored by the Portland Cement Association * BMS63 Moisture Condensation in Building Walls * BMS64 Solar Heating of Various Surfaces lOp

BMS65 Methods of Estimating Loads in Plumbing Systems * BMS66 Plumbing Manual 40^ BMS67 Structural Properties of “Mu-Steel” Prefabricated Sheet-Steel Constructions for Walls,

Partitions, Floors, and Roofs, Sponsored by Herman A. Mugler 20^ BMS68 Performance Test for Floor Coverings for Use in Low-Cost Housing: Part 3 * BMS69 Stability of Fiber Sheathing Boards as Determined by Accelerated Aging 10^ BMS70 Asphalt-Prepared Roll Roofings and Shingles 20t BMS71 Fire Tests of Wood- and Metal-Framed Partitions 30f BMS72 Structural Properties of “Precision-Built, Jr.” Prefabricated Wood-Frame Wall Construction Sponsored by the Homasote Co * BMS73 Indentation Characteristics of Floor Coverings lOf BMS74 Structural and Heat-Transfer Properties of “U. S. S. Panelbilt” Prefabricated SheetSteel Constructions for Walls, Partitions, and Roofs Sponsored by the Tennessee

Coal, Iron & Railroad Co 20P BMS75 Survey of Roofing Materials in the North Central States * BMS76 Effect of Outdoor Exposure on the Water Permeability of Masonry Walls * BMS77 Properties and Performance of Fiber Tile Boards * BMS78 Structural, Heat-Transfer, and Water-Permeability Properties of Five Earth-Wall

Constructions 35c BMS79 Water-Distributing Systems for Buildings 20c BMS80 Performance Test of Floor Coverings for Use in Low-Cost Housing: Part 4 2oc BMS81 Field Inspectors’ Check List for Building Constructions (cloth cover 5 x 7}^ inches) 40c BMS82 Water Permeability of Walls Built of Masonry Units 25c BMS83 Strength of Sleeve Joints in Copper Tubing Made With Various Lead-Base Solders BMS84 Survey of Roofing Materials in the South Central States * BMS85 Dimensional Changes of Floor Coverings With Changes in Relative Humidity and

Temperature * BMS86 Structural, Heat-Transfer, and Water-Permeabilitv Properties of “Speedbrik” Walt

Construction Sponsored by the General Shale Products Corporation • BMS87 A Method for Developing Specifications for Building Construction—Report of Sul>- committee on Specifications of the Central Housing Committee on Research,

Design, and Construction .. ... *

• Out of print.

[List continued on cover page iv]
BUILDING MATEEIALS AND STKUCTUEES KEPORTS

[Continued from cover page inj

BMS88 Recommended Building Code Requirements for New Dwelling Construction With

Special Reference to War Housing * BMS89 Structural Properties of “Precision-Built, Jr.” (Second Construction) Prefabricated Wood-Frame Wall Construction Sponsored by the Homasote Co * BMS90 Structural Properties of “PHC” Prefabricated Wood-Frame Constructions for Walls,

Floors, and Roofs Sponsored by the PHC Housing Corporation * BMS91 A Glossary of Housing Terms * BMS92 Fire-Resistance Classifications of Building Constructions 35fi BMS93 Accumulation of Moisture in Walls of Frame Construction During Winter Exposure. . * BMS94 Water Permeability and Weathering Resistance of Stucco-Faced, Gunite-Faced, and

“Knap Concrete-Unit” Walls * BMS95 Tests of Cement-Water Paints and Other Waterproofings for Unit-Masonry Walls 30fi BMS96 Properties of a Porous Concrete of Cement and Uniform-Sized Gravel * BMS97 Experimental Dry-Wall Construction With Fiber Insulating Board * BMS98 Physical Properties of Terrazzo Aggregates * BMS99 Structural and Heat-Transfer Properties of “Multiple Box-Girder Plywood Panels” for Walls, Floors, and Roofs * BMSlOO Relative Slipperiness of Floor and Deck Surfaces * BMSIOI Strength and Resistance to Corrosion of Ties for Cavity Walls * BMS102 Painting Steel 15(4 BMS103 Measurements of Heat Losses From Slab Floors * BMS104 Structural Properties of Prefabricated Plywood Lightweight Constructions for Walls,

Partitions, Floors, and Roofs Sponsored by the Douglas Fir Plywood Association. * BMS105 Paint Manual with particular reference to Federal Specifications $1.50

BMS106 Laboratory Observations of Condensation in Wall Specimens 15^ BMS107 Building Code Requirements for New Dwelling Construction * BMS108 Temperature Distribution in a Test Bungalow With Various Heating Devices 15^ BMS109 Strength of Houses: Application of Engineering Principles to Structural Design 70^ BMSllO Paints for Exterior Masonry Walls 20^ BMSlll Performance of a Coal-Fired Boiler Converted to Oil 15^ BMS112 Properties of Some Lightweight-Aggregate Concretes With and Without an Air- Entraining Admixture 15(4 BMS113 Fire Resistance of Structural Clay Tile Partitions 15f4 BMS114 Temperature in a Test Bungalow With Some Radiant and Jacketed Space Heaters 25^ BMS115 A Study of a Baseboard Convector Heating System in a Test Bungalow 20^ BMS116 Preparation and Revision of Building Codes 20^ BMS117 Fire Resistance of Walls of Lightweight Aggregate Concrete Masonry Units 25^ BMS118 Stack Venting of Plumbing Fixtures 25^ BMS119 Wet Venting of Plumbing Fixtures 25^ BMS120 Fire Resistance of Walls of Gravel-Aggregate Goncrete Masonry Units 15(4 BMS121 Investigation of Failures of White-Coat Plasters 30(4 BMS122 Physical Properties of Some Samples of Asbestos-Cement Siding 20(4 BMS123 Fire Tests of Wood-Framed Walls and Partitions With Asbestos-Cement Facings * BMS124 Fire Tests of Steel Columns Protected With Siliceous Aggregate Concrete 15^ BMS125 Stone Exposure Test Wall 30(4 BMS126 The Self-Siphonage of Fixture Traps 200 BMS127 Effect of Aging on the Soundness of Regularly Hydrated Dolomitic Lime Putties 150 BMS128 Atmospheric Exposure Tests of Nailed Sheet Metal Building Materials 200 BMS129 Fire Endurance of Shutters for Moving-Stairway Openings 100 BMS130 Methods and Equipment for Testing Printed-Enamel Felt-Base Floor Covering 150 BMS131 Fire Tests of Gunite Slabs and Partitions 150 BMS132 Capacities of Plumbing Stacks in Buildings 250 B MS133 Live Loads on Floors in Buildings 250 BMS134 Fire Resistance of Concrete Floors * BMS135 Fire Tests of Steel Columns Encased With Gypsum Lath and Plaster 150 BMS136 Properties of Cavity Walls 150 BMS137 Influence of the Wash From Bronze on the Weathering of Marble 150 BMS138 Effect of Edge Insulation Upon Temperature and Condensation on Concrete-Slab

Floors 200 BMS139 Studies of Stone-Setting Mortars 250 BMS140 Second Edition, Selected Bibliography on Building Construction and Maintenance— 300 BMS141 Fire Endurance of Open-Web Steel Joist Floors With Concrete Slabs and Gypsum

Ceilings 200 BMS142 Frost Closure of Roof Vents 250 BMS143 Fire Tests of Brick Walls 350 BMS144 Sound Insulation of Wall, and Floor Constructions 400 Supplement to BMS144, Sound Insulation of Wall, Floor, and Door Constructions 50 BMS145 Fire Effects and Fire Control in Nitrocellulose Photographic-Film Storage 200 BMS146 Plasticity and Water Rententivity of Hydrated Limes for Structural Purposes 150 BMS147 Effects of Mineral Additives on the Durability of Coating-Grade Roofing Asphalts 200 BMS148 Fifteen-Year Exposure Test of Porcelain Enamels ** BMS149 Combustible Contents in Buildings ** BMS150 Methods of Testing Small Fire Extinguishers 150