Small-scale fire extinguishment test on mechanical foam. Part II

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Small-scale fire extinguishment test on mechanical foam. Part II

NATIONAL RESEARCH COUNCIL CANADA

D I V I S I O N O F B U I L D I N G RESEARCH

SMALL-SCALE

FIRE

M T I N G U I SHMENT T E S T ON MECHANICAL FOAM PAm I1 by K. S u m i I n t e r n a l R e p o r t No. 230 of t h e D i v i s i o n of B u i l d i n g R e s e a r c h rnTAWA S e p t e m b e r 1961

PREFACE

The c o n s i d e r a t i o n s l e a d i n g t o t h e s e a r c h f o r a small-scale f i r e extinguishment t e s t f o r mechanical foam, t o g e t h e r with t h e r e s u l t s of preliminary i n v e s t i g a t i o n s made with one foam l i q u i d and a 2- by 2 - f t t a n k have a l r e a d y been presented i n DBR Report 224 covering P a r t I of t h i s study. An extension of t h i s work t o include s i x foam l i q u i d s and t h e use of 3 - f t and 1 0 - f t t a n k s i n a d d i t i o n t o t h e 2 - f t t a n k a r e now presented. The r e s u l t s obtained a r e considered t o be s u f f i c i e n t j u s t i f i c a t i o n f o r s e r i o u s c o n s i d e r a t i o n of t h e

2 - f t t a n k t e s t f o r foam e v a l u a t i o n , when c a r r i e d out i n accordance w i t h t h e procedure proposed i n t h e r e p o r t .

!he a u t h o r , a chemical engineer and a. r e s e a r c h o f f i c e r i n t h e F i r e Research Section of t h e Division, i s engaged i n s t u d i e s of v a r i o u s a s p e c t s of f i r e extinguishment.

Ottawa

SMALL-SCALE FIRE EXTINGUISHI'AENT TEST ON

MECHANICAL

FOAM

PART II

by

K.

Sumi

An i n v e s t i g a t i o n d i r e c t e d toward t h e development of a small-scale f i r e extinguishment t e s t t o a s s e s s t h e performance p o t e n t i a l of mechanical foam over a wide range of c h a r a c t e r i s t i c s was described i n a previous r e p o r t (1).

The purpose of t h e p r e s e n t s t u d y was t o i n v e s t i g a t e f u r t h e r t h e p o t e n t i a l i t i e s of t h e new f i r e t e s t .

PRESENT INVESTIGATION

I t was decided t o e s t a b l i s h a procedure f o r t h e small-scale f i r e extinguishment t e s t t o f i n d o u t i f t h e technique being i n v e s t i g a t e d would provide a s u i t a b l e means t o examine r e l a t i v e degrees of e f f e c t i v e n e s s of d i f f e r e n t brands of foam l i q u i d .

The r e s u l t s obtained i n t h e e a r l i e r i n v e s t i g a t i o n (1) were used a s t h e b a s i s f o r t h e procedure.

The e a r l i e r work i n d i c a t e d t h a t t h e f o l l o w i n g

experimental c o n d i t i o n s appeared optimum f o r t h e suppression of a 2- by 2 - f t flammable l i q u i d f i r e by foam:

( a ) S o l u t i o n r a t e of a p p l i c a t i o n =

0.06 gal/min/sq f t of f u e l s u r f a c e .

( b ) !Twenty-five p e r c e n t drainage time of foam = 2 t o 4 min.

( c ) Expansion r a t i o of foam = 1 2 .

The 25 p e r c e n t drainage time i s t h e time a t which 25 p e r c e n t of foam s o l u t i o n i s drained from a sample of foam i n a standard foam c o n t a i n e r ( 3 , 5 ) and i s a n index of t h e degree of s t a b i l i t y and of f l u i d i t y of t h e foam. Ekpansion r a t i o i s t h e r a t i o of t h e f i n a l foam volume t o t h e o r i g i n a l foam s o l u t i o n volume.

The optimum v a l u e s given above were based on t h e measurement of "control" time which was defined a s t h e time a f t e r foam a p p l i c a t i o n a t which t h e r a d i a t i o n i n t e n s i t y from

t h e f i r e i s decreased t o 10 p e r c e n t of t h e maximum v a l u e reached d u r i n g t h e pre-burn period. The optimum v a l u e s obtained f o r s o l u t i o n r a t e o f a p p l i c a t i o n and 25 p e r c e n t drainage time were i n good agreement w i t h t h o s e determined by previous i n v e s t i g a t o r s and appear s u i t a b l e f o r a d o p t i o n

i n t h e t e s t procedure. The v a l u e determined f o r t h e

expansion r a t i o was h i g h e r t h a n expected and t h e r e was some q u e s t i o n a s t o whether expansion r a t i o of 12 i s t h e most l o g i c a l f o r use i n t h e new procedure, p a r t i c u l a r l y i n view of t h e f a c t t h a t c o n t r o l time was used a s t h e end-point t o o b t a i n t h e optimum v a l u e s and extinguishment time was ignored.

Consideration was a l s o given t o t h e s e l e c t i o n of t h e most s u i t a b l e s i z e of t a n k f o r conducting t h e f i r e t e s t s , I n t h e e a r l i e r i n v e s t i g a t i o n t h e 2- by 2 - f t t a n k was a r b i t r a r i l y selecT3d f o r t h e i n d o o r f i r e t e s t s . There was _{some doubt a s}

t o whether t h i s was t h e most s u i t a b l e s i z e a s t o convenience f o r conducting t h e f i r e t e s t s and t o r e l i a b i l i t y o f r e s u l t s . It w a s decided, t h e r e f o r e , t o c a r r y o u t a s e r i e s

o f

r e p l i c a t e t e s t s u s i n g t h e 2- by 2 - f t t a n k , a 3- by 3 - f t t a n k and a 10- by 10-ft t a n k , and t o determine both c o n t r o l time and complete extinguishment time.

A f t e r t h e . t e s t procedure was e s t a b l i s h e d , it was

decided t o c a r r y o u t a s e r i e s of r e p l i c a t e t e s t s u s i n g d i f f e r e n t brands of commercially a v a i l a b l e " 6 _{p e r c e n t}

Regular" mechanical foam l i q u i d . This type of foam l i q u i d , which i s g e n e r a l l y recommended f o r use a t normal temperatures i n p r o p o r t i o n s of 6 p a r t s of foam l i q u i d t o 94 p a r t s of w a t e r , i s covered i n J F M C S p e c i f i c a t i o n No. 260.00. ( 2 )

A. FURTHER DEVELOPMENT OF TEST PROCEDURE EXPERIMENTAL DETAILS

The purpose of t h e p r e s e n t s e r i e s of experiments was t o e s t a b l i s h a t e s t procedure f o r use a s a means t o a s s e s s t h e q u a l i t y of foam l i q u i d . The s e l e c t i o n of a s u i t a b l e s i z e sf t a n k f o r conducting t h e f i r e t e s t s and of t h e expansion r a t i o of foam f o r t h e procedure were examined u s i n g t h e new f i r e t e s t .

1. Procedure

F i r e t e s t s were c a r r i e d o u t u s i n g a 6 p e r c e n t

Regular mechanical foam l i q u i d which had met t h e requirements of JFMC S p e c i f i c a t i o n No. 260.00.

( a ) 2- by 2 - f t f i r e t e s t

Ten r e p l i c a t e t e s t s were c a r r i e d out a t each of t h e expansion r a t i o s 8, 1 0 and 1 2 , a t s o l u t i o n r a t e of a p p l i c a t i o n of 0.060 gal/min/sq f t of f u e l s u r f a c e and

25

p e r c e n t

d r a i n a g e time of about 3 minutes.

The procedure was a s f o l l o w s : A 2-in. l a y e r of heptane was f l o a t e d on 2 i n . of w a t e r i n a f i r e t a n k 2 by

2 by 1 f t deep. A f t e r a pre-burn p e r i o d of 60 seconds, foam produced by a v a r i a b l e foam g e n e r a t a r was d i s c h a r g e d from a p o s i t i o n d i r e c t l y above t h e mid-point of one w a l l of t h e tank. !The foam stream was d i r e c t e d a c r o s s

tibe

f i r e t o s t r i k e t h e o p p o s i t e s i d e of t h e t a n k , which was w e d a s t h e backboard, about 4 i n . above t h e f u e l s u r f a c e .

C o n t r o l time was determined By t h e use of a gold- d i s c r a d i o m e t e r ( 4 ) connected t o a m i l l i v o l t r e c o r d e r . The r a d i o m e t e r was _{p o s i t i o n e d 6 f t from one}

of

_{t h e s i d e s of t h e}

t a n k p a r a l l e l t o t h e d i r e c t i o n of t h e foam stream a t a n e l e v a t i o n of 2 f t above t h e to^ of t h e tank. C o m ~ l e t e extinguishment time which i s d e f i n e d a s t h e time a f t e r foam a p p l i c a t i o n a t which t h e l a s t f l i c k e r of flame i s e l i m i n a t e d w a s a l s o determined.

( b ) 3- by 3 - f t f i r e t e s t

Ten r e p l i c a t e t e s t s were a l s o c a r r i e d o u t w i t h t h e

3-

by 3 - f t tank. Experimental c o n d i t i o n s f o r expansion r a t i o , s o l u t i o n r a t e of a p p l i c a t i o n and 25 p e r c e n t d r a i n a g e time were t h e same a s f o r t h e 2- by 2 - f t t e s t .

Experimental d e t a i l s were s i m i l a r t o t h o s e of t h e 2- by 2 - f t t e s t b u t w i t h t h e f o l l o w i n g m o d i f i c a t i o n s . !The s i z e of t h e f i r e t a n k was

3

by

3

by 1 f t deep. The backboard was i n c r e a s e d t o a h e i g h t of 16 i n . The foam stream was

d i r e c t e d t o s t r i l c e t h e backboard a b o u t 6 in, above t h e f u e l s u r f a c e . The radiometer was l o c a t e d i n approximately t h e same geometric p o s i t i o n w i t h r e s p e c t t o t h e t a n k and t h e n o z z l e a s w i t h t h e 2 - by 2 - f t t e s t . The r a d i o m e t e r was

p o s i t i o n e d 6 f t from t h e n e a r e s t s i d e of t h e t a n k and 4 f t above t h e t o p of t h e tank.

( c ) 10- by 1 0 - f t f i r e t e s t

Ten r e p l i c a t e t e s t s were c a r r i e d o u t i n accordance w i t h t h e procedure f o r f i r e t e s t d e s c r i b e d i n JFMC S p e c i f i c a t i o n No. 260.00. Fewer t e s t s were c a r r i e d o u t w i t h t h i s t a n k because t h e c h a r a c t e r i s t i c s of foam cannot be v a r i e d i n t h i s t e s t .

T h i s t e s t procedure i s a s follows: A minimum of 150 g a l l o n s of g a s o l i n e i s f l o a t e d on 200 g a l l o n s of w a t e r i n a f i r e t a n k 1 0 by 1 0 by 3 f t deep. A f t e r a pre-burn p e r i o d

.of 60 seconds foam i s discharged through a standard 5-gpm n o z z l e , supplied w i t h water a t a pressure o f 100 p s i . The foam stream i s d i r e c t e d from a p o s i t i o n j u s t above t h e s i d e of t h e t a n k a c r o s s t h e f i r e t o s t r i k e t h e approximate c e n t r e of t h e opposite t a n k w a l l a t r i g h t a n g l e s . The foam i s a p p l i e d f o r

5

minutes. Visual observations a r e recorded during t h e t e s t .

One important modification i n t h e p r e s e n t s t u d y was t h e use of radiometers t o determine c o n t r o l time. Two r a d i o - meters were used t o provide two s e t s of r e s u l t s . One r a d i o - meter ( R - 1 ) was l o c a t e d i n approximately t h e same geometric p o s i t i o n w i t h r e s p e c t t o t h e t a n k and t h e nozzle a s i n t h e s m a l l e r t e s t s . T h i s radiometer was p o s i t i o n e d 25 f t from t h e n e a r e s t s i d e of t h e t a n k a t an e l e v a t i o n of 1 2 f t above t h e t o p of t h e tank. The second radiometer

( R - 2 )

was posi-Zoned d i r e c t l y behind t h e nozzle 20 f t from t h e n e a r e s t s i d e of t h e t a n k and 12 f t above t h e t o p of t h e tank.

2. R e s u l t s

The r e s u l t s of t h i s s e r i e s of experiments a r e

presented i n Tables .I and 11. The 25 p e r c e n t drainage time of foam was about 3 minutes f o r a l l t h e experiments.

TABLE

I

CONTROL TIME ( a ) Radiometer R - 1 ( b ) Radiometer R-2 Coeff. of V a r i a t i o n , p e r c e n t 4 6 4 5

5

7 15 15 Control Time, min. 1.04 0.98 0.92 1

.

10 1.06 1.04 1.39 ( a > 1.27 ( b ) Size of F i r e 2 f t by 2 f t

3

f t by

3

f t 1 0 f t by 1 0 f t Ekpansion Ratio 8 1 0 1 2 8 1 0 12 8

TABLE I1 EXTINGUISrnXENT TIME 3. Discussion Size of P i r e 2 f t by 2 f t 3 f t b y 3 f t

The most e f f e c t i v e expansion r a t i o of foam based on c o n t r o l time i n t h e s e experiments was 1 2 , followed by 10 and t h e n 8. T h i s r e s u l t a g r e e s w i t h t h e e a r l i e r work (1). llhe most e f f e c t i v e expansion r a t i o based on extinguishment time was, however, 1 0 , followed by 1 2 and t h e n 8. These r e s u l t s were i n agreement f o r t h e 2- by 2 - f t t e s t and t h e 3- by 3 - f t t e s t .

Control time appeared t o i n c r e a s e s l i g h t l y a s t h e s i z e of t h e t e s t was increased. The i n c r e a s e i n t h e c o n t r o l time between t h e r e s u l t s of t h e 2- by 2 - f t t e s t and those of t h e

3-

by 3 - f t t e s t was 6 t o 11 p e r c e n t ; t h e i n c r e a s e between t h e r e s u l t s of t h e 3- by 3 - f t t e s t and those of t h e 10- by 1 0 - f t t e s t was 22 t o 34 p e r c e n t . These percentage i n c r e a s e s a r e very small compared t o t h e i n c r e a s e i n t h e s i z e of t h e f i r e . Ekpansion Ratio 8 10 1 2 8 10 1 2

Extinguishment time increased s l i g h t l y a s t h e s i z e of t h e t e s t was increased from 2 by 2 f t t o 3 by 3 f t . This percentage i n c r e a s e (12 t o 16 p e r c e n t ) i s very small compared t o t h e i n c r e a s e i n t h e s i z e of t h e f i r e . Thus extinguishment time can be considered t o be very n e a r l y t h e same f o r t h e 2- by 2 - f t t e s t and t h e 3- by 3 - f t t e s t . I n g e n e r a l , complete extinguishment was n o t obtained i n

5

minutes f o r t h e 10- by 1 0 - f t t e s t .

The r e p r o d u c i b i l i t y of r e s u l t s f o r a

2-

b y 2 - f t t e s t appears t o be very s l i g h t l y b e t t e r than f o r a 3- by 3 - f t

Extinguishment Time, min. 3.1-1 2.46 2.65 3.49 2.77 3.07 Coeff. of V a r i a t i o n , p e r c e n t 7 11 1 2 1 3 15 9

t e s t . Both s m a l l e r t e s t s gave b e t t e r r e p l i c a t i o n t h a n t h e 10- by 1 0 - f t t e s t . The c h i e f reason f o r t h i s d i f f e r e n c e i s probably due t o t h e f a c t t h a t t h e 10- by 1 0 - f t t e s t s were conducted outdoors, whereas t h e s m a l l e r t e s t s were conducted indoors.

The two radiometers used f o r t h e 10- by 1 0 - f t t e s t s produced c o n t r o l times t h a t agreed w e l l w i t h each o t h e r . The c o e f f i c i e n t s of v a r i a t i o n determined from t h e s e r e s u l t s a l s o agreed w e l l .

The q u e s t i o n t h a t a r r i s e s i s whether t h e 2- by 2 - f t t a n k i s a s r e l i a b l e a s a 10- by 1 0 - f t t a n k which i s now used f o r a s s e s s i n g t h e q u a l i t y of foam l i q u i d .

A c o n s i d e r a t i o n of dimensions involved indicu-tLes

t h a t t h e s i z e of t h e t a n k can be considered i n f i n i t e l y l a r g e i n uomparison t o t h e s i z e of t h e bubbles. This o b s e r v a t i o n i s v a l i d r e g a r d l e s s of whether a 2- by 2 - f t t a n k o r a 10- by 1 0 - f t t a n k were considered. A f u r t h e r examination of r a t i o of dimensions i n d i c a t e s t h a t t h e foam must be t r a n s - ported a l o n g d i s t a n c e over t h e f u e l s u r f a c e w i t h r e s p e c t t o i t s t h i c k n e s s . The t h i c k n e s s of foam b l a n k e t f o r t h e 2- by 2 - f t t e s t s was about

3

inches when t h e f i r e was completely extinguished. This value i n f l u e n c e s t h e p r o c e s s of movement of foam over t h e f u e l s u r f a c e . The r a t i o of maximum d i s t a n c e t h a t t h e foam h a s t o t r a v e l t o t h e thiclrness of foam b l a n k e t i s about 8. Thus t h e d i s t a n c e t h a t t h e foam i s t r a n s p o r t e d i n a 2- by 2 - f t t a n k may be d e s c r i b e d a s l a r g e . A s m a l l e r t a n k , however, seems u n d e s i r a b l e .

E m i s s i v i t i e s of flames of t h e n a t u r e t h a t a r e b e i n g considered tend t o u n i t y when dimensions of t h e o r d e r of 4 f t a r e involved. Flame h e i g h t s f o r a 2- by 2 - f t

t e s t were a t l e a s t 6 f t when t h e foam was f i r s t a p p l i e d . Thus, t h e r e a r e no obvious r e a s o n s why t h e r e s u l t s obtained u s i n g a 2- by 2 - f t t a n k should n o t be a t l e a s t a s adequate

a

t e s t of foam q u a l i t y a s t h o s e obtained u s i n g a 10- by 1 0 - f t tank.

4.

Conclusions, S e c t i o n A

The experimental r e s u l t s and d i s c u s s i o n l e a d t o t h e conclusion t h a t t h e 2- by 2 - f t t e s t should be a t l e a s t a s adequate a s t h e 10- by 1 0 - f t t e s t a s a means t o a s s e s s t h e q u a l i t y of foam l i q u i d .

Thus, t h e procedure e s t a b l i s h e d w i l l be based on t h e use of a 2- by 2 - f t tank. The expansion r a t i o of 10 was s e l e c t e d f o r i n c l u s i o n i n t h e t e s t procedure. This expansion r a t i o of foam y i e l d e d t h e lowest extinguishment time and i s more l i k e l y t o be met i n p r a c t i c e t h a n a n expansion r a t i o of 12 which yielded t h e lowest c o n t r o l time.

B. EXAMINATION OF D I F l ? E W T BFANDS

_-

OF

_-

FOAM LIQUID

The procedure f o r a s m a l l - s c a l e f i r e extinguishment t e s t t o a s s e s s t h e q u a l i t y of mechanical foam l i q u i d , a s

e s t a b l i s h e d i n S e c t i o n A of t h i s r e p o r t , i s d e s c r i b e d i n d e t a i l i n Appendix A i n t h e form of a t e s t method. S e v e r a l d i f f e r e n t brands of foam l i q u i d were examined i n t h e f o l l o w i n g s e r i e s of experiments u s i n g t h e method developed.

EXPERIMENTAL DETAILS 1. Procedure

I n o r d e r t o examine t h e s u i t a b i l i t y of t h e new f i r e t e s t f o r use i n a s s e s s i n g t h e q u a l i t y of foam l i q u i d on t h e b a s i s of c o n t r o l time and extinguishment time t e n r e p l i -

c a t e t e s t s were conducted w i t h each of s i x d i f f e r e n t commercially a v a i l a b l e brands o f 6 p e r c e n t Regular mechanical foam l i q u i d . The t e s t s were conducted u s i n g t h e 2- by 2 - f t t a n k a s d e s c r i b e d

i n S e c t i o n A. The main p o i n t s i n t h e t e s t procedure were: ( a ) S o l u t i o n r a t e of a p p l i c a t i o n =

0.06 gal/min/sq f t of f u e l s u r f a c e . ( b ) 25 p e r c e n t drainage time = 3 min.

( c ) Expansion r a t i o = 10.

2. R e s u l t s

The r e s u l t s of t h i s s e r i e s of experiments a r e presented i n Tables 111 and I V .

TABLE 111 CONTROL TIME Coeff. of V a r i a t i o n , p e r c e n t 6 8 5 6 6 8 Foam Liquid A B C D E

F

Control Time, min

.

0.98 1.20 1.09 0.92 1.08 1 . 1 2

TABLE I V MTINGTJISllWIENT

TIME

3.

Discussion Foam Liquid A B C D E

F

The mean c o n t r o l t i m e s f o r t h e s i x brands of

6

p e r c e n t Regular mechanical foam l i q u i d examined were i n t h e range 0.92 min. t o 1.20 rnin, and t h e mean extinguishment times were i n t h e range 2.28 rnin. t o 2.71 min.

The p o t e n t i a l use of t h e new f i r e t e s t t o a s c e r t a i n t h e q u a l i t y of foam l i q u i d was considered. It i s b e l i e v e d t h a t it would be reasonable t o c a r r y o u t t h r e e r e p l i c a t e t e s t s t o determine i f a foam l i q u i d would meet t h e r e q u i r e - ments of t h i s f i r e t e s t . The r e l i a b i l i t y of t h e t e s t would be i n c r e a s e d by making it mandatory t h a t a l l t h r e e r e p l i c a t e t e s t s s a t i s f y t h e acceptance l e v e l s f o r b o t h c o n t r o l time and extinguishment time. Ektinguishment Time, min

.

2.46 2.71 2. 34 2.28 2.46 2.38 C a l c u l a t i o n s were made t o c o n s i d e r e s t a b l i s h i n g t h e acceptance l e v e l s f o r both c o n t r o l time and extinguishment time. Suppose t h r e e r e p l i c a t e t e s t s a r e t o be conducted and t h e c o n t r o l time f o r each t e s t i s t o be l e s s t h a n 1.25 min. Using t h e t a b l e s of t h e a r e a of t h e normal curve it can be shown t h a t t h r e e r e p l i c a t e t e s t s c a r r i e d out u s i n g each of t h e s i x brands of mechanical foam l i q u i d w i l l provide t h e r e s u l t s g i v e n s i n Table V which i n d i c a t e t h e p r o b a b i l i t y t h a t a l l t h r e e r e p l i c a t e t e s t s w i l l meet t h e acceptance l e v e l . One of t h e brands t h a t y i e l d e d t h e p o o r e s t r e s u l t s h a s a chance of 1 i n 3 of meeting t h e acceptance l e v e l .

Coeff, o f V a r i a t i o n , p e r c e n t 11 8

7

9 6 6 The c a l c u l a t i o n s a l s o i n d i c a t e t h a t a l l t h e o t h e r brands examined w i l l meet t h e requirements f o r c o n t r o l time i n a m a j o r i t y of cases. Suppose t h i s requirement i s eased and t h e acceptance l e v e l f o r t h e c o n t r o l time i s r a i s e d t o

1.5

min. Then a l l s i x brands w i l l have a chance g r e a t e r t h a n 99 i n 100 of meeting t h i s acceptance l e v e l . Since none

of t h e brands appeared u n u s u a l l y l e s s e f f e c t i v e t h a n t h e o t h e r s , a requirement of 1 . 5 min. appears r e a s o n a b l e f o r t h e acceptance l e v e l f o r t h e c o n t r o l time.

S i m i l a r c a l c u l a t i o ~ i s on t h e extinguishment time provided r e s u l t s shown i n Table V I .

The a u t h o r i s of t h e opinion t h a t t h e c o n t r o l time i s more important t h a n t h e extinguishment t i m e i n a s s e s s i n g t h e q u a l i t y of foam l i q u i d . The a b i l i t y of foam t o e x t i n g u i s h f l i c k e r s of flames a t c o m e r s of a square t a n k i s considered t o be of secondary importance. I n p r a c t i c e , s i n c e t h e n o z z l e s a r e movable, t h e d u r a t i o n of time between t h e c o n t r o l time and t h e extinguishment time is g e n e r a l l y n o t g r e a t . On t h e o t h e r hand, i n t h e experiments i n which a f i x e d nozzle was used,

t h e d u r a t i o n of t i m e between t h e c o n t r o l time and t h e e x t i n g u i s h - ment was g r e a t e r t h a n t h e time r e q u i r e d t o c o n t r o l t h e f i r e .

Thus, a l i m i t of 4.0 min. a p p e a r s r e a s o n a b l e f o r t h e acceptance l e v e l f o r t h e extinguishment time.

The degree of c o r r e l a t i o n between c o n t r o l time and complete extinguishment time f o r t h e r e s u l t s of experiments i n v o l v i n g s i x d i f f e r e n t brands of foam l i q u i d was examined. The c o r r e l a t i o n c o e f f i c i e n t was found t o be 0.7, i n d i c a t i n g a f a i r degree of c o r r e l a t i o n between t h e two t e s t c r i t e r i a . Although t h e a u t h o r h a s suggested acceptance l e v e l s f o r b o t h c o n t r o l time and complete extinguishment time i n t h e p r e s e n t r e p o r t , accumulated d a t a from a c t u a l t e s t s might l e a d t o t h e conclusion t h a t complete extinguishment time could be e l i m i n a t e d from t h e t e s t method.

TABLE V

PROBABILITY OF THREE FlEPLICATE TESTS MEETING SELECTED ACCEPTANCE LEVELS FOR CONTROL TIME

Foam Liquid A B C D E F Acceptance Level f o r Control Time 1.25 min. 7 0 . 9 9 0.33 7 0 . 9 9 20.99 0.99 0.77 1.5 min. pO.99 7 0 . 9 9 7 0 . 9 9 7 0 . 9 9 7 0 . 9 9 7 0 . 9 9

TABLE V I

PROBABILITY OF THREE REPLICATE TESTS MEETING

SELECTED ACCER?ANCE LEVELS FOR EXTINGUISHMENT TIME

4. Conclusions, S e c t i o n B Foam Liquid A B C D E

F

R e p l i c a t e f i r e t e s t s u s i n g s i x d i f f e r e n t brands of 6 p e r c e n t Regular mechanical foam l i q u i d i n d i c a t e t h a t

r e a s o n a b l e acceptance l e v e l s a r e :

( a ) The c o n t r o l time f o r each o f t h r e e r e p l i c a t e t e s t s s h a l l be l e s s t h a n

1 . 5

min.

Acceptance Level f o r Extinguishment Time

( b ) The extinguishment time f o r each of t h r e e r e p l i c a t e t e s t s s h a l l be l e s s t h a n

4

min. 3.0 min. 0.93 0.75 ' >0.99 7 0 . 9 9 70.99 2 0 . 9 9 CONCLUSIONS

3.5

min.

7

0.99 >0.99 7 0.99 >0.99 >0.99 >0.99

1. A new f i r e t e s t , u s i n g a t a n k 2 by 2 by 1 f t deep has

been developed f o r c o n s i d e r a t i o n a s replacement f o r t h e 10- by 1 0 - f t t e s t d e s c r i b e d i n JFMC S p e c i f i c a t i o n No. 260.00.

D e t a i l s of t h e new t e s t a r e given i n t h e Appendix t o t h i s r e p o r t .

2. The new t e s t h a s a number of advantages over t h e p r e s e n t

10- by 10-ft t e s t :

( a ) Because t h e f i r e t a n k i s s m a l l , t h e t e s t can be conducted i n d o o r s , i n a n atmosphere a b s e n t from t h e i n f l u e n c e o f weather.

(b) The r e d u c t i o n i n expense f o r conducting t h e

( c ) The c o n t r o l time appears t o be of t h e same o r d e r of magnitude f o r t h e 2- by 2 - f t t e s t a s f o r t h e 10- by 1 0 - f t t e s t .

( d ) The r e p r o d u c i b i l i t y of r e s u l t s a r e b e t t e r f o r t h e new t e s t t h a n f o r t h e 10- by 1 0 - f t t e s t . ( e ) The use of a radiometer f o r c o n t r o l time

reduces t h e r e l i a n c e on v i s u a l observation and t h e r e s p o n s i b i l i t y placed on t h e

observer.

3. The new t e s t procedure was developed f o r 6 p e r c e n t Regular mechanical foam l i q u i d . This t e s t i s a l s o

s u i t a b l e , however, f o r examining o t h e r t y p e s of mechanical foam l i q u i d , e. g., 3 p e r c e n t Regular mechanical foam

l i q u i d .

The a u t h o r wishes t o thank Messrs.

E.

_L. Mulligan, A. L. Opseth, E. W. Oracheski and C. Wolfgram f o r conducting t h e f i r e t e s t s .

The 10- by 1 0 - f t t e s t s were c a r r i e d out a t I n s p e c t i o n S e r v i c e s Proof Establishment of t h e Department of National

Defence i n N i c o l e t , Quebec, with t h e co-operation of t h e Superintendent and members of h i s s t a f f .

(1) Sumi, K. Small-scale f i r e extinguishment t e s t on

mechanical foam, P a r t I. National Research Council, Division of Building Research, I n t e r n a l Report No. 224, Ottawa, June 1961.

( 2 ) J o i n t F i r e Marshals Committee S p e c i f i c a t i o n No. 260.00 F i r e Extinguishing Agent

-

Foam Liquid (Mechanical Airfoam) February 12, 1958, 1 2 p.

( 3 ) National F i r e P r o t e c t i o n Association Standard No. 11

-

1960, Foam Extinguishing Systems.

( 4 ) McGuire, J. H. and H. Wraight. Radiometer f o r f i e l d use. Journal of S c i e n t i f i c Instruments, Vol. 37, A p r i l 1960, p. 128-130.

( 5 )

Tuve, R. L. and He B. Peterson. A study o f some

mechanical foams and t h e i r use f o r e x t i n g u i s h i n g t a n k f i r e s . Naval Research Laboratory Report 3725, Washington, D O C u , 'August 23, 1950,

8 9

p.

THE Nl3Y FIFU3 TRST

The t a n k used f o r t h e f i r e t e s t s h a l l be of s t e e l o o n s t r u o t i o n measuring 2 f t square by 1 f t deep. Four g a l l o n s of heptane, t h e volume e q u i v a l e n t of a 2-in. l a y e r i n t h i s t a n k , s h a l l be f l o a t e d on 2 i n . of water.

A $-in. nozzle s h a l l be p o s i t i o n e d d i r e c t l y above t h e mid-point of one of t h e s i d e s of t h e t a n k and about

4

i r ~ above t h e s i d e . A gold-disc radiometer connected t o a

m i l l i v o l t r e c o r d e r s h a l l be used t o determine t h e c o n t r o l time. Control time i s defined a s t h e time a f t e r foam a p p l i - c a t i o n a t which t h e r a d i a t i o n i n t e n s i t y from t h e f i r e i s decreased t o 10 p e r c e n t of t h e maximum value reaohed d u r i n g t h e preburn period. The radiometer s h a l l be positioned 6 f t from one of t h e s i d e s o f t h e t a n k p a r a l l e l t o t h e d i r e c t i o n of t h e foam stream a t a n e l e v a t i o n of 2 f t above t h e t o p of t h e tank.

The foam i s produced by a v a r i a b l e foam g e n e r a t o r a t a s o l u t i o n r a t e of 0.24 g a l l o n s p e r minute. The foam l i q u i d c o n c e n t r a t i o n s h a l l be 6 per cent. The expansion r a t i o of foam s h a l l .be 10 and t h e 25 p e r c e n t drainage time s h a l l be about

3

min.

The f i r e s h a l l be permitted t o burn f r e e l y f o r 60 seconds before foam a p p l i c a t i o n . The foam stream s h a l l be d i r e c t e d a c r o s s t h e f i r e t o s t r i k e t h e approximate c e n t r e of t h e t a n k w a l l a t r i g h t a n g l e s . The foam stream s h a l l be

a p p l i e d u n t i l t h e f i r e i s completely extinguished o r f o r 4 _min.,

whichever i s l e s s . Control ti-me and complete extinguishment time s h a l l be recorded.

Three r e p l i c a t e t e s t s s h a l l be conducted. Requirements of F i r e Test

The c o n t r o l time s h a l l be l e s s t h a n 1.5 rnin. f o r each t e s t . The complete extinguishment time s h a l l be l e s s t h a n 4.0 rnin. f o r each t e s t .