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NATIONAL RESEARCH COUNCIL O F CANADA D I V I S I O N O F B U I L D I N G RESEARCH
EVALUATION T E S T S ON
33
-GALLON CHEMICAL FOAM E X T I N G U I S H E R SK. S u m i and D.G. R o b e r t s o n R e p o r t No. 144 o f 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 O t t a w a June
1958
PREFACE
T h i s r e p o r t d e s c r i b e s work c a r r i e d o u t t o a s s i s t t h e F i r e M a r s h a l ' s Branch, C o n s t r u c t i o n E n g i n e e r i n g
D i r e c t o r a t e ,
R.C.A.F.,
i n t h e e v a l u a t i o n of chemical foam e x t i n g u i s h e r s . It i s i n c l u d e d i n t h e r e g u l a r r e p o r ts e r i e s o f t h e D i v i s i o n , but w i t h t h e i d e n t i t y o f t h e p r o p r i e t a r y p r o d u c t s concealed by coding, so t h a t t h e d e s c r i p t i o n of t h e methods used may be made a v a i l a b l e t o o t h e r s . The c h i e f c h a r a c t e r i s t i c t o b e e v a l u a t e d was t h e a b i l i t y of t h e foam t o a d h e r e t o t h e i n c l i n e d m e t a l
s u r f a c e s o f c e r t a i n p a r t s of a i r c r a f t f o r p r o t e c t i o n when a p p l i e d d u r i n g hangar f i r e s .
These r e p o r t s which a r e e s s e n t i a l l y p r i v a t e documents have a l i m i t e d c i r c u l a t i o n , r e s t r i c t e d mainly t o i n d i v i d u a l s known t o t h e D i v i s i o n who a r e engaged i n
s i m i l a r work.
Ottawa, June 1958
N.B. Hutcheon,
T A B U OF CONTENTS
Page
. . .
.
PART I PRELIMINARY INVESTIGATIONS 1
. . .
1
.
Experimental D e t a i l s 1. . .
(a) Discharge C h a r a c t e r i s t i c s of Chemical Foam 2
. . .
( b ) Small-scale Adhesion Experiments
. . .
( c ) Other T e s t s
PART I1
.
EVALUATION TESTS ON CHEMICAL FOAM EXTINGUISHERS( 3 3 4 A L . 1
0 . .5
. . .
.
1 D e s c r i p t i o n of E x t i n g u i s h e r5
2.
Apparatus. . .
63
.
Development of T e s t Procedure. . .
6. . .
( a ) S i z e o f P a n e l. . .
6
( b ) A p p l i c a t i o n Period. . .
7
( c ) Distance f o r F o a r n A p p l i c a t i o n. . . .
7
( d ) combinations S e l e c t e d f o r Adhesion T e s t s7
. . .
4
.
Procedure6
.
D i s c u s s i o n. . .
8
APPENDIXE V A L U A T I O N TESTS ON
?'?-GALLON CHEMICAL FOAM EXTINGUIS~RS &.
-
K.
Sumi and D.G. RobertsonThe F i r e M a r s h a l ' s Branch, C o n s t r u c t i o n E n g i n e e r i n g D i r e c t o r a t e , R.C.A.F., r e q u e s t e d t h e D i v i s i o n of B u i l d i n g Research, on 9 May, 1955, t o a s s i s t t h e R.C.A.F. i n p r e p a r i n g a s p e c i f i c a t i o n f o r t h e e v a l u a t i o n o f 3 3 - g a l l o n (40-U. S.
g a l l o n ) c h e m i c a l foam e x t i n g u i s h e r s and c h a r g e s . One o f t h e main r e a s o n s f o r t h i s r e q u e s t was t o o b t a i n a n independent
e v a l u a t i o n on t h e a d h e s i v e q u a l i t y of c h e m i c a l foam. S e v e r a l m e e t i n g s were h e l d between t h e i n t e r e s t e d p a r t i e s and
i t
w a s d e c i d e d t h a t t h e F i r e S e c t i o n of t h i s D i v i s i o n s h o u l d( a ) d e v e l o p a t e s t p r o c e d u r e t o d e t e r m i n e t h i s p r o p e r t y ,
( b ) c a r r y o u t t e s t s on e x t i n g u i s h e r s and c h e m i c a l c h a r g e s s u b m i t t e d by t h e R.C.A.F. and ( c ) a s s i s t t h e R.C.A.F. i n w r i t i n g a s p e c i f i c a t i o n based on t h e t e s t methods developed.
Three i n d i v i d u a l 3 3 - g a l l o n c h e m i c a l foam e x t i n g u i s h e r s and c h a r g e s from f i v e f i r m s were p r o v i d e d by t h e R.C.A.F. f o r t h i s i n v e s t i g a t i o n . The t h r e e e x t i n g u i s h e r s a r e d e s i g n a t e d i n t h i s r e p o r t a s E-1, E-2 and E-3. The chemical c h a r g e s p r o v i d e d f o r t h i s i n v e s t i g a t i o n a r e d e s i g n a t e d a s C - 1 , C-2,
C-3,
C-4
andC-5.
PART I. PRELIMINARY INVESTIGATIONS
P r e l i m i n a r y i n v e s t i g a t i o n s i n c l u d e d s m a l l - s c a l e a d h e s i o n e x p e r i m e n t s c a r r i e d o u t t o t e s t chemical foam. An a t t e m p t was made t o c o r r e l a t e t h e r e s u l t s o f t h e s e e x p e r i m e n t s w i t h o t h e r p r o p e r t i e s of foam, such a s e x p a n s i o n r a t i o , pH and c r i t i c a l s h e a r i n g s t r e s s .
1. E x p e r i m e n t a l D e t a i l s
The normal "A" and "B" c h a r g e s f o r a 3 3 - g a l l o n
e x t i n g u i s h e r were d i s s o l v e d s e p a r a t e l y i n two l a r g e c o n t a i n e r s a c c o r d i n g t o t h e i n s t r u c t i o n s o f t h e m a n u f a c t u r e r . The two
s o l u t i o n s were allowed t o s t a n d f o r about ono day, t h e n t h e y were s t i r r e d b e f o r e b e i n g poured i n t o t h r e e 2 - g a l l o n e x t i n g u i s h e r s which were used t o g e n e r a t e r e l a t i v e l y s m a l l q u a n t i t i e s of foam.
The number of r e f i l l s p e r b a t c h was l i m i t e d t o a maximum of
15
because i n some c a s e s an a r e c i a b l e q u a n t i t y of i n s o l u b l e m a t t e r was p r e s e n t i n t h e s o l u t i o n which s e t t l e d t o t h e bottom of t h e l a r g e c o n t a i n e r a f t e r s t a n d i n g f o r a s h o r t t i m e . The p o r t i o n of t h e"B"
s o l u t i o n t h a t had a h i g h c o n c e n t r a t i o n o f i n s o l u b l e m a t t e r was d i s c a r d e d . The t h r e e 2 - g a l l o n e x t i n g u i s h e r s u s e d i n t h e p r e l i m i n a r y experiments were s e l e c t e d f o r t h e i r s i m i l a r i t y t o each o t h e r . The e f f e c t i v e d i s c h a r g e p e r i o d f o r a 2 - g a l l o n e x t i n g u i s h e r i s aboutSO
s e c .(a) Discharge C h a r a c t e r i s t i c s of Chemical Foam
Three r s p e a t t e s t s wGre c a r r i e d o u t w i t h each o f t h e t h r e e s m a l l e x t i n g u i s h e r s i n o r d e r t o i n v e s t i g a t e t h e d i s c h a r g e c h a r a c t e r i s t i c s of chemical foam. The volume and weight o f
foam d i s c h a r g e d i n t o f i v e c a n s d u r i n g t h e i n t e r v a l s 0 t o 10 s e c , 10 t o 20 s e c , 20 t o 30 s e c , 30 t o
40
s e c and 40 t o 50 s e c ,r e s p e c t i v e l y , from t h e s t a r t of d i s c h a r g e were measured. These t e s t s were r e p e a t e d f o r each of t h e chemical c h a r g e s . Grapha of volume and weight of foam g e n e r a t e d w i t h r e s p e c t t o time a r e g i v e n i n F i g s . 1 and 2. The mean v a l u e s o f n i n e d e t e r m i n a t i o n s were used i n p l o t t i n g t h e s e g r a p h s . The f i r s t o f t h e s o two g r a p h s shows t h a t t h e volume r a t e of foam d i s c h a r g e r e a c h e s a maximum i n e i t h e r t h e 10 t o 20-sec i n t e r v a l o r t h e 20 t o 30-sec
i n t e r v a l , and t h e n d e c r e a s e s . The second g r a p h shows t h a t t h e weight r a t e of d i s c h a r g e r e a c h e s a rnaxiinum i n t h e 0 t o 10-sec o r 1 0 t o 20-sec p e r i o d , and t h e n d e c r e a s e s . The r e l a t i v e l y low volume o f foam d i s c h a r g e d i n t h e 0 t o 10-sec i n t e r v a l ( F i g . 1) i s l a r g e l y due t o t h e low expansion r a t i o of foam g e n e r a t e d i n t h a t p e r i o d , The foam g e n e r a t e d i n t h e f i r s t i n t e r v a l was
v e r y w a t e r y ; i t s q u a l i t y g r a d u a l l y improved, r e a c h i n g i t s optimum i n t h e 20 t o 30-sec i n t e r v a l and s u s t a i n i n g
it
i n t h e l o n g e r i n t e r v a l s .The mean w e i g h t s of foam and t h e i r s t a n d a r d d e v i a t i o n s f o r t h e 10 t o 20-sec and 20 t o 30-sec i n t e r v a l s a r e i n c l u d e d i n Table I a s t h e s e means were u s e d i n t h e subsequent s m a l l - s c a l e a d h e s i o n experiments.
The volume and weight measurements were used i n
c a l c u l a t i n g t h e expansion r a t i o o f foam f o r each o f t h e f i v e 10-sec i n t e r v a l s , The s p e c i f i c g r a v i t i e s o f t h e " A " and "B"
s o l u t i o n s were measured w i t h a hydrometer and t h e s e v a l u e s were used i n making a p p r o p r i a t e c o r r e c t i o n s t o t h e expansion r a t i o .
The g r a p h of expansion r a t i o w i t h r e s p e c t t o t i m e ( F i g .
3 )
shows t h a t t h e expansion r a t i o r e a c h e s a maximum about t h e 20 t o 30-sec i n t e r v a l and remains f a i r l y c o n s t a n t ,( b ) Small-scale Adhesion Experiments
S m a l l - s c a l e a d h e s i o n experiments were c a r r i e d o u t u s i n g t h e 2 - g a l l o n chemical foam e x t i n g u i s h e r s . Foam was a p p l i e d a s even1 a s p o s s i b l e f o r 10 s e c t o a 3 - f t square " d u r a l " s h e e t
1/8
i n . t h i c k , suspended v e r t i c a l l y from a b a l a n c e . The d i s t a n c e between t h e n o z z l e of a n e x t i n g u i s h e r and t h e aluminum a l l o y s h e e t was f i x e d a t14
f t.
The o b s e r v a t i o n s of t h e d i s c h a r g e c h a r a c t e r i s t i c s of foam i n d i c a t e d bhe v a r i a t i o n i n t h e q u a l i t y o f foam a t
s u c c e s s i v e 10-sec i n t e r v a l s . The foam d i s c h a r g e d i n t h e 10 t o 20-sec i n t e r v a l was, i n g e n e r a l , a mixture of watery and good q u a l i t y foams and t h e foam d i s c h a r g e d i n t h e n e x t p e r i o d ,
i . e , , 20 t o 30 s e c s , was of about optimum q u a l i t y .
One t e s t was c a r r i e d o u t w i t h each of t h e t h r e e e x t i n g u i s h e r s t o d e t e r m i n e t h e a d h e s i v e q u a l i t y of chemical foam f o r t h e 10 t o 20-sec i n t e r v a l . The time a f t e r a p p l i c a t i o n a t which 50 p e r c e n t by weight of t h e foam d i s c h a r g e d i n t h i s 10-sec i n t e r v a l ( b a s e d on p r e v i o u s d e t e r m i n a t i o n s ) s t ill
adhered t o t h e " d u r a l " s h e e t was r e c o r d e d
( 3
d e t e r m i n a t i o n s ) . The r e s u l t s of t h i s experiment a r e d e s i g n a t e d''SO
p e r c e n t adherence t i m e s " i n t h i s r e p o r t , The s m a l l - s c a l e a d h e s i o n experiments were r e p e a t e d w i t h t h e t h r e e s m a l l e x t i n g u i s h e r s f o r t h e 20 t o 30-sec d u r a t i o n( 3
d e t e r m i n a t i o n s ) . These experiments f o r t h e 1 0 t o 20-sec and 20 t o 30-sec i n t e r v a l s were c a r r i e d o u t w i t h f i v e d i f f e r e n t chemical charges.The "50 p e r c e n t adherence times" of t h e s m a l l - s c a l e a d h e s i o n experiments a r e r e c o r d e d i n Table I.
The r e s u l t s of t h e s m a l l - s c a l e a d h e s i o n experiments i n d i c a t e d t h a t f o r t h e LO
t o
20-sec i n t e r v a l t h e b e s t chemical c h a r g e s were C - 1 and C-2. The r e s u l t s a l s o i n d i c a t e d t h a t t h e a d h e s i v e q u a l i t y was g r e a t e r f o r a l l t h e c h a r g e s i n t h e 20 t o 30-sec i n t e r v a l . The s m a l l - s c a l e a d h e s i o n experiment i s u s e f u l a s a p r e l i m i n a r y a d h e s i o n t e s t f o r foam provided t h e r e s u l t s f o r b o t h t h e 10 t o 20-sec and 20 t o 30-soc i n t e r v a l s a r e c o n s i d e r e d . T h i s s t a t e m e n t i s borne o u t by t h e r e s u l t s of t h e l a r g e - s c a l e t e s t s d e s c r i b e d i n P a r t 11 of t h i s r e p o r t .( c ) Other T e s t s
An a t t e m p t was made t o c o r r e l a t e t h e r e s u l t s of t h e s m a l l - s c a l e a d h e s i o n e x p e r i m e n t s w i t h o t h e r p r o p e r t i e s o f foam. Measurements of expansion r a t i o , pH and c r i t i c a l s h e a r i n g s t r e s s were made, a g a i n u s i n g s m a l l e x t i n g u i s h e r s . The foam was
c o l l e c t e d i n f i v e c a n s f o r 10-sec i n t e r v a l s a s i n p r e v i o u s work.
The volume measurements were r e f i n e d f o r t h i s experiment i n o r d e r t o o b t a i n more a c c u r a t e r e s u l t s of expansion r a t i o
t h a n t h o s e r e p o r t e d e a r l i e r . A b r a s s pan,
13
i n . i n s i d e d i a m e t e r by 1 1/2 i n . d e p t h , was p l a c e d i n t h e bottom of each c a n f o rc o l l e c t i n g foam. The foam above t h e edge o f t h e pan was s c r a p e d o f f w i t h a s t r a i g h t edge a s evenly a s p o s s i b l e and t h e weight of foam i n t h e pan was determined. Care was t a k e n %n t h e t i m i n g f o r s c r a p i n g o f f e x c e s s foam s o t h a t t h e volume i n each p a n
would b e measured a t t h e same t i m e a f t e r foam g e n e r a t i o n . The e x c e s s foam above t h e t o p of t h e pan was d i f f i c u l t t o remove evenly i f t h e foam e x h i b i t e d good a d h e s i v e q u a l i t y . Thus, t h i s d e s i r a b l e p r o p e r t y of a d h e s i o n t e n d e d t o i n t e r f e l - e w i t h t h i 3
d e t e r m i n a t i o n . Approximate v a l u e s of e x p a n s i o n r a t i o were o b t a i n e d by t h i s method which could be f u r t h e r m o d i f i e d and improved i f g r e a t e r accuracy were r e q u i r e d .
The r e s u l t s i n d i c a t e d t h a t t h e expansion r a t i o of chemical foam i s n o t always r e l a t e d t o i t s a d h e s i v e p r o p e r t y . Other experiments c a r r i e d o u t i n t h e c o u r s e of t h i s i n v e s t i g a t i o n showed t h a t t h e q u a l i t y of t h e foam i n t h e e a r l y s t a g e s o f
d i s c h a r g e c o u l d be improved i f t h e p r e s s u r e were allowed t o b u i l d up i n t h e e x t i n g u i s h e r , ( e . g . , by h o l d i n g a thumb a t t h e
end of a noz7,le f o r a s h o r t p e r i o d ) . 'I'his i n t e r e s t i n g a s p e c t c o u l d b e i n v e s t i g a t e d f u r t h e r .
The p H of foam f o r t h e f i v e 10-sec i n t e r v a l s was measured w i t h a Heckman pA m e t e r (model
H-2).
The pII o f foam was found t o v a r y f o r d i f f e r e n t d u r a t i o n s a f t e r s t a r t of d i s c h a r g e b u t 1 . t ~ v a r i a t i o n d i d n o t c o r r e l a t e w i t h t h e r e s u l t s of t h e s m a l l - s c a l e a d h e s i o n experiments.The c r i t i c a l s h e a r i n g s t r e s s of chemical foam was determined by a method d e s c r i b e d by Clarlr ( I ) , w i t h some modif i c a t i o n s .
The c r i t i c a l s h e a r i n g s t r e s s of chemical foam measured was n o t very a c c u r a t e , The v a r i a t i o n i n t h e p r o p e r t i e s o f foam was s i g n i f i c a n t even though th.e foam was g e n e r a t e d u s i n g
p r o p e r t i e s of c h e m i c a l foam cha.nge w i t h t i m e and t h i s i s v e r y c r i t i c a l i n t h e measurement under c o n s i d e r a t i o n . The measurement of c r i t i c a l s h e a r i n g s t r e s s r e q u i r e s a p p r o x i m a t e l y 30 s e c , and v i s u a l o b s e r v a t i o n i n d i c a t e d t h a t t h e chemical r e a c t i o n s t i l l c o n t i n u e d d u r i n g t h i s measurement. F u r t h e r improvement i n b o t h t h e meth-od of foam g e n e r a t i o n and t h e measurement of c r i t i c a l s h e a r i n g s t r e s s a p p e a r s t o be p o s s i b l e b u t , because o f t i m e l i m i t a t i o n , t h i s work was not c o n t i n u e d .
The p r e l i m i n a r y work i n d i c a t e d t h a t a performance-type t e s t i s most s u i t a b l e f o r e v a l u a t i n g 3 3 - g a l l o n c h e m i c a l foam e x t i n g u i s h e r s and c h a r g e s w i t h r e s p e c t t o t h e a d h e s i v e q u a l i t y of foam, A l a r g e - s c a l e a d h e s i o n t e a t was devel-oped, t h e r e f o r e , and i s d e s c r i b e d i n P a r t I1 of t h i s r e p o r t .
PART 11, EVALUATION TESTS O N CHEMICAL FOAM EXTINGUISHERS
GAL.
)The main work of t h i s r e p o r t d e s c r i b e d i n t h i s s e c t i o n d e a l s w i t h t h e l a r g e - s c a l e a d h e s l o n t e s t developed by t h e
D i v i s i o n , Foam g e n e r a t e d from a 3 3 - g a l l o n e x t i n g u i s h e r was a p p l i e d t o a v e r t i c a l l y suspended " d u r a l " p a n e l , 7 f t h i g h by 1 2 f t wide, f o r a n a r b i t r a r i l y s e l e c t e d a p p l i c a t i o n p e r i o d . The weight o f foam a d h e r i n g t o t h e p a n e l was d e t e r m i n e d a t c o n s t a n t t i m e i n t e r v a l s a f t e r a p p l i c a t i o n . Measurements were a l s o made t o d e t e r m i n e t h e volume of foam g e n e r a t e d from
33-
g a l l o n e x t i n g u i s h e r s and t h e s e a r e g i v e n i n t h e Appendix.
1. D e s c r i p t i o n o f E x t i n g u i s h e r
The r u n n i n g g e a r of t h i s e x t i n g u i s h e r c o n s i s t s of two wheels, a n a x l e , a t a n k and a handle. The t a n k h a s p r o v i s i o n f o r a n i n n e r c y l i n d e r and a g a s k e t e d cap which i s t h r e a d e d t o t h e c o l l a r o f t h e t a n k , A s t r a i n e r i s p r o v i d e d i n t h e t a n k
t o p r o t e c t t h e d i s c h a r g e o u t l e t which i s connected t o a SO-ft l e n g t h o f 1
1/4.
i n , r u b b e r hose w i t h a n a t t a c h e d n o z z l e . Acompression s t o p f i t s and s e a l s t h e t o p of t h e i n n e r c y l i n d e r u n t i l t h e o p e r a t i n g mechanism a t t a c h e d t o t h e s t o p i s opened.
The "B" c h a r g e (sodium b i c a r b o n a t e and a foam s t a b i l i z i n g a g e n t ) i s d i s s o l v e d i n w a t e r and poured i n t o t h e t a n k o f t h e
e x t i n g u i s h e r . The "A" c h a r g e (aluminum s u l p h a t e ) i s d i s s o l v e d i n w a t e r and poured i n t o t h e i n n e r c y l i n d e r . The cap i s t h r e a d e d t o t h e t a n k and t h e o p e r a t i n g mechanism i s c l o s e d . The
The f i r s t s t e p i n v o l v e d i n d i s c h a r g i n g foam i s t o open t h e o p e r a t i n g mechanism which c o n s i s t s o f a t h r e a d e d
o p e r a t i n g stem o r s p i n d l e p a s s i n g t h r o u g h t h e cap o f t h e t a n k . T h i s c a u s e s t h e s t o p t o d i s e n g a g e from t h e t o p o f
t h e i n n e r c y l i n d e r p r o v i d i n g s u f f i c i e n t c l e a r a n c e t o r e l e a s e t h e chemical c h a r g e from t h i s c y l i n d e r , The e x t i n g u i s h e r i s t i l t e d from a n u p r i g h t p o s i t i o n u n t i l . t h e h a n d l e r e s t s on t h e ground; t h i s a l l o w s t h e "A" and "BIT s o l u t i o n s t o mix, The foam i s produced, and t h e p r e s s u r e c r e a t e d by t h e
e v o l u t i o n of carbon d i o x i d e w i t h i n t h e t a n k e x p e l s foam t h r o u g h t h e hose and n o z z l e ,
2. Apparatus
A f l ~ t r e c t a n g u l a r p a n e l , 1 2 f t wide by 7 f t high, was c o n s t r u c t e d from f o u r s h e e t s o f 1/8-in. " d u r a l " , The
s h e e t s were s t i f f e n e d t o form a p a n e l by spot-welding t o a s u i t a b l e frame of 1 1/4-in. by 1 l-/k-in. "dural'l a n g l e s . The p a n e l was mounted v e r t i c a l l y on a s u i t a b l e s u p p o r t frame of
s t a n d a r d s t e e l s c a f f o l d i n g u n i t s . It was h e l d i n a v e r t i c a l p l a n e by f o u r s h o r t , h o r i z o n t a l l y p i v o t e d l i n k a g e s which
a f f i x e d
it
t o t h e s t e e l frame. A p r o v i n g r i n g o r f o r c e gauge was i n c l u d e d i n t h e p a n e l s u p p o r t arranement so t h a t t h ep a n e l was c o n t i n u o u s l y weighed on t h e gauge,
F i g u r e s
4
t o 7 i l l u s t r a t e v a r i o u s f e a t u r e s o f t h e a p p a r a t u s used f o r t h i s t e s t .G r i d l i n e s were p a i n t e d on t h e p a n e l ( F i g .
6 )
t o p r o v i d e a t a r g e t a r e a of s i x t y 1-ft s q u a r e s , l e a v i n g a one- f o o t b o r d e r a t t h e t o p and two s i d e s of t h e p a n e l , The purpose of t h e s e l i n e s was t o a s s i s t t h e o p e r a t o r of t h e e x t i n g u i s h e r t o a p p l y foam a s e v e n l y a s p o s s i b l e .3.
Development of T e s t ProcedureSome e x p l o r a t o r y i n v e s t i g a t i o n s w i t h 3 3 - g a l l o n c h e m i c a l foam e x t i n g u i s h e r s were c a r r i e d o u t t o a s s i s t i n t h e development of a proceduro f o r t h e l a r g e - s c a l e a d h e s i o n t e s t .
( a ) S i z e o f P a n e l
The s i z e of t h e p a n e l d e s i g n e d was a compromise between b e i n g l a r g e enough t o y i e l d dependable r e s u l t s and b e i n g t o o cumbersome f o r t h e e x p e r i m e n t s , A t a r g e t a r e a o f s i x t y 1-ft
s q u a r e s was s e l e c t e d so t h a t a p p l i c a t i o n p e r i o d s of foam t o p a n e l of
1s
s e c , 30 s e c , 1 min, e t c . , c o u l d be i n v e s t i g a t e d ,( b ) A p p l i c a t i o n P e r i o d
E x p l o r a t o r y i n v e s t i g a t i o n s w i t h 3 3 - g a l l o n e x t i n g u i s h e r s i n d i c a t e d t h a t t h e p r o p e r t i e s of c h e m i c a l foam v a r y d u r i n g t h e d i s c h a r g e p e r i o d . The foam g e n e r a t e d e a r l y i n t h e p e r i o d , g e n e r a l l y h a s low e x p a n s i o n r a t i o and poor a d h e s i v e q u a l i t y . The q u a l i t y o f foam a p p e a r e d t o improve a s t h e d i s c h a r g e p r o g r e s s e d , The a u t h o r s , t h e r e f o r e , d e c i d e d t o ornit t h e
d e t e r m i n a t i o n o f t h e a d h e s i v e q u a l i t y o f foam g e n e r a t e d i n t h e f i r s t 30 s e c by d i s c h a r g i n g t h i s foam t o w a s t e . The most
s u i t a b l e a p p l i c a t i o n p e r i o d o f foam t o p a n e l was found t o b e between 30 and 60 s e c a f t e r s t a r t of d i s c h a r g e . A l o n g o r p e r i o d of a p p l i c a t i o n was n o t s u i t a b l e b e c a u s e of t h e i n c r e a s e d t e n d e n c y of t h e foam s t r e a m t o d i s l o d g e t h e foam a l r e a d y a d h e r i n g t o t h e p a n e l . A s h o r t e r d u r a t i o n , on t h e o t h e r hand, w a s n o t s u f f i c i e n t f o r t h e foam t o c o v e r t h e t a r g e t a d e q u a t e l y w i t h o u t l e a v i n g t o o many u n p r o t e c t e d a r e a s , The a p p l i c a t i o n p e r i o d s e l e c t e d was n o t n e c e s s a r i l y t h e one i n which t h e foam had r e a c h e d i t s optimum a d h e s i v e q u a l i t y , b u t was a compromise
between g i v i q g t h e e x t i n g u i s h e r enough t i n e t o g e n e r a t e t h e b e s t foam p o s s i b l e and a l l o w i n g so much t i m e t h a t t o o much foam was g e n e r a t e d b e f o r e t e s t i n g f o r t h i s p r o p e r t y .
( c ) D i s t a n c e f o r Foam A p p l i c a t i o n
The d i s t a n c e from which foam s h o u l d b e a p p l l e d t o t h e p a n e l w a s a l s o c o n s i d e r e d . The U n d e r w r i t e r s ! s t a n d a r d f o r 3 3 - g a l l o n foam e x t i n g u i s h e r s ( 2 ) s p e c i f i e s , " t h e d u r a t i o n of foam s t r e a m w i t h good r a n g e ( 2 0 t o 60
f t )
s h a l l n o t b e l e s s t h a n two m i n u t e s " . The minimum d i s t a n c e o f 20 f t was s e l e c t e d so t h a t t h i s work would n o t c o n f l i c t w i t h t h e U n d e r w r i t e r s 1 r e q u i r e m e n t s . Such a c o n f l i c t c o u l d o c c u r i f some g r e ~ t e r d i s t a n c e , e.g., 30 f t , were s e l e c t e d . The p e r f o r ~ a n c e o f an e x t i n g u i s h e r c o u l d s a t i s f y t h e r e q u i r e m e n t s i n e v e r y r e s p e c t b u t i t s d i s c h a r g e d u r i n g t h e a p p l i c a t i o n p e r i o d of t h i s l a r g e -s c a l e a d h e s i o n t e s t may be l e s s t h a n 30 f t . Another i m a g i n a r y example c o u l d be made f o r a d i s t a n c e l e s s t h a n 20 f t , e . g . ,
15
f t . An e x t i n g u i s h e r may g e n e r a t e foam which i s ~ a t i s f a . c t o r y , a c c o r d i n g t o t h i s a d h e s i o n t e s t , b u t i t s r a n g e may n o t s a t i s f y t h e U n d e r w r i t e r s r e q u i r e x e n t s .( d ) c o m b i n a t i o n s S e l e c t e d f o r Adhesion T e s t s
E x t i n g u i s h e r E-1 and c h e m i c a l c h a r g e s C - 1 t o C - 5 w e r e
s e l e c t e d f o r u s e i n t h e l a r g e - s c a l e a d h e s i o n t e s t s b a s e d on a method o f e l i m i n a t i o n described i n t h e Appendix.
4..
ProcedureL a r g e - s c a l e a d h e s i o n t e s t s were c a r r i e d o u t u s i n g e x t i n g u i s h e r E - 1 and t h e f i v e d i f f e r e n t c h e m i c a l c h a r g e s , Chemical c h a r g e s were mixed a c c o r d i n g t o t h e i n s t r u c t i o n s of t h e m a n u f a c t u r e r and t h e two s o l u t i o n s were poured i n t o e x t i n g u i s h e r E-1. A f t e r t h e two s o l u t i o n s had remained i n t h e e x t i n g u i s h e r f o r one day, t h e l a r g e - s c a l e a d h e s i o n t e s t was performed,
Foam was a p p l i e d t o t h e l a r g e v e r t i c a l p a n e l from a d i s t a n c e of 20 f t a f t e r a n i n i t i a l d i s c h a r g e p e r i o d of 30 s e c , Foam was a p p l i e d t o t h e p a n e l f o r a p e r i o d of 30 s e c ( i . e . , w i t h
an a p p l i c a t i o n r e t e of about 2 sq f t of p a n e l s u r f a c e p e r s e c ) . The weight of foam a d h e r i n g t o t h e p a n e l was r e c o r d e d a t
r e g u l a r t i m e i n t e r v a l s a f t e r t h e end of a p p l i c a t i o n . T h i s measurement was d i s c o n t i n u e d a f t e r 1 0 min, o r when t h e weight
of foam on t h e panel. became l e s s t h a n 10 l b ,
The l a r g e - s c a l e a d h e s i o n t e s t s were c a r r i e d o u t i n
d u p l i c a t e w i t h f o u r of t h e f i v e combinations, i , e . , e x t i n g u i s h e r E-1 w i t h c h a r g e s C - 1 , C-3,
C-4
andC - 5
r e s p e c t i v e l y . The f i r s t two r e s u l t s of t h e o t h e r combination, i , e . , e x t i n g u i s h e r E-1w i t h chemical charge C - 2 , d i d n o t show good agreement. T h i s combination, t h e r e f o r e , was used i n a t h i r d t e s t .
5 .
--
R e s u l t sThe r e s u l t s of l a r g e - s c a l e a d h e s i o n t e s t s a r e t a b u l a t e d i n T a b l e
11.
6 . D i s c u s s i o n
-
The a u t h o r s b e l i e v e t h a t t h e r e s u l t s of t h e l a r g e - s c a l e a d h e s i o n t e s t and t h e volume measurements ( g i v e n i n t h e Appendix)
w i l l b e u s e f u l i n e v a l u a t i n g m e r i t s of e x t i n g u i s h e r s and chemical c h a r g e s .
C e r t a i n l i m i t a t i o n s i n t h e a d h e s i o n t e s t s , however, should b e p o i n t e d o u t . The r e s u l t s of t h e s e t e s t s a r e o n l y g i v e n i n terms of t h e weight of foam a d h e r i n g t o t h e p a n e l and no a l l o w a n c e i s made f o r t h e u n i f o r m i t y o f p r o t e c t i o n on t h e p a n e l . The foam o f t e n d r o p s o f f o r s l i d e s o f f t h e p a n e l i n chunks, exposing u n p r o t e c t e d s l i r f a c e s even though t h e weight of foam a d h e r i n g t o t h e p a n e l may b e r e l a t i v e l y high.
The adhesion t e s t s were a l l c a r r i e d out under one s e t o f c o n d i t i o n s : ( a ) foam was a p p l i e d t o a v e r t i c a l l y suspended " d u r a l " p a n e l , ( b ) t h e t a r g e t a r e a was 1 0 f t wide by 6 f t high, ( c ) t h e a p p l i c a t i o n p e r i o d was 30 sec t o 60 sec a f t e r s t a r t of d i s c h a r g e and ( d ) t h e d i s t a n c e between t h e n o z z l e of t h e
e x t i n g u i s h e r and t h e panel was 20 f t .
Any change i n t h e s e c o n d i t i o n s may y i e l d q u i t e d i f f e r e n t r e s u l t s . T h i s should be borne i n mind i n any e v a l u a t i o n of
33-gallon chemical foam e x t i n g u i s h e r s and charges on t h e b a s i s of t e s t s d e s c r i b e d i n t h i s r e p o r t ,
Acknowledgment
The a u t h o r s wish t o thank M r , P, Huot f o r h i s a s s i s t a n c e i n t h e development of t h e t e s t procedures.
References
1. Clark, N,O, A study of mechanically produced foam f o r combatting p e t r o l f i r e s , Great B r i t a i n , D.S. 1,R.
Chemistry Research S p e c i a l Report No.
6,
London, 1947. 112p.2. U n d e r w r i t e r s ' L a b o r a t o r i e s of Canada, Standard f o r foam e x t i n g u i s h e r s ( 3 3 - g a l l o n ) . J u l y 1950.
lkp.
mo-s
ri
-
cu- ,v d,. boa-
c r l k oJ d n # O 3 d W U E -:F
r i dc 4
rsla-
hj 0 A a h a - G-l a * 4 b t 0 G O d d a d E E aa-
4 G P E-i W 4APPENDIX Volume Measurements
V i s u a l o b s e r v a t i o n d u r i n g t h e e x p l o r a t o r y i n v e s t i g a t i o n w i t h 3 3 - g a l l o n e x t i n g u i s h e r s i n d i c a t e d t h a t a g i v e n c o m b i n a t i o n of e x t i n g u i s h e r and c h e m i c a l c h a r g e s may n o t p r o d ~ l c e enough foam o f a s u f f i c i e n t l y h i g h e x p a n s i o n r a t i o f o r combating flammable l i q u i d f i r e s . 3 x p l o r a t o r y i n v e s t i g a t i o n s i n d i c a t e d t h a t , i n g e n e r a l , foam w i t h low e x p a n s i o n r a t i o g i v e s poop p e r f o r m a n c e i n b o t h t h e p r e l i m i n a r y s m a l l - s c a l e a d h e s i o n
e x p e r i m e n t and t h e l a r g e - s c a l e a d h e s i o n t e s t ,
Measurements of foakn volume, t h e r e f o r e , were made by d i s c h a r g i n g foam from a n e x t i n g u i s h e r i n t o a measuring box,
The U n d e r w r i t e r s ' sta.ndard ( 2 ) s p c c L f i e s t h a t t h e volume o f
foam produced must b e a t l e a s t 250 g a l l o n s . The a u t h o r s b e l i e v e t h a t i t i s r e a s o n a b l e t o r e j e c t ally c o m b i n a t i o n of e x t i n g u i s h e r and c h e m i c a l c h a r g e s which f a i l s t o g e n e r a t e a t l e a s t 250
i m p e r i a l g a l l o n s o f foam, Thus, l a r g e - s c a l e a d h e s i o n t e s t s were n o t c a r r i e d o u t f o r s u c h c o m b i n a t i o n s which r e s u l t e d i n t h e
r e d u c t i o n o f l a r g e - s c a l e adhesion t e s t s t o a p r a c t i c a l number, Also, t h e r e s u l t s o f t h o volume measurements s h o u l d b e h e l p f u l i n any e v a l u a t i o n of t h e m e r i t s o f e x t i n g u i s h e r s and c h e m i c a l c h a r g e s .
P r o c e d u r e
Foam was d i s c h a r g e d i n t o a r e c t a n g u l a r box ( b a s e d i m e n s i o n
4
f t b y4
f t ) by h o l d i n g t h e n o z z l e of t h o e x t i n g u i s l ~ c r a t a h e i g h t of a b o u t8
f t above t h e b a s e of t h e box. C a r e w a s t a k e n t o d i r e c t t h e foam s t r e a m a g a i n s t one of t h s s i d e s o f t h e bo:c, j u s t above t h e foam l e v e l , u n t i l most of t h e foam was dischal.gcd.A n a r r o w p l e x i g l a s window showing t h e d e p t h o f t h e box g r a d u a t e d i n i n c h e s was p r o v i d e d t o f a c i l i t a t e t h e e s t l m a t l o n o f foam
volume. The volume o f foam w a s measured a f t e r t h e foam w a s
c o m p l e t e l y d i s c h a r g e d i n t o t h e box,
Foam volume measurements were made i n d u p l i c a t e f o r e v e r y c o m b i n a t i o n of e x t i n g u i s h e r and c h e m i c a l c h a r g e s u p p l f ed by t h e R.C,A,F,
R e s u l t s
The r e s u l t s o f t h e volume measurements a r e g i v e n i n T a b l e A w l w
TABLE A - 1
T o t a l volume of foam g e n e r a t e d
Chemical Volume o f F'oam E x t i n g u i s h e r Charges (imp. g a l . ) Run I Run 2
c
-1 380 370c
-2 3203
20 270 260 C- 320330
260 250The r e s u l t s of t h e volume measurements showed t h a t
extinguisher E-1 g e n e r a t e d a t l e a s t 250 i m p e r i a l g a l l o n s of f o a m w i t h each of t h e chemical c h a r g e s s u p p l i e d . The o t h e r two e>.+ i n g u i s h e r s d i d n o t produce t h e r e q u i r e d q u a n t i t y o f foam w i t h any of t h e s e c h a r g e s . Adhesion t e s t s were t h e r e f o r e carried o u t o n l y w i t h e x t i n g u i s h e r E-1 and t h e f i v e d i f f e r e n t c h e m i c a l c h a r g e s .
F B g w e
4
" D w a P " panel suependad f r o m ateel. f~arneworkFZgura
