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Performance test on foam-compatible dry chemical powders
NATIONAL RESEARCH COUNCIL CANADA
DIVISION O F BUILDING RESEARCH
PERFORMANCE TEST ON F O M -COMPATIBLE DRY CHEMICAL POWDERS
by
K.
Sumi Internal R e p o r t No.258
of the Division of Building R e s e a r c hA N A L Y Z E D
OTTAWA July1962
P R E F A C E
A s s i s t a n c e was r e q u e s t e d by Inspection S e r v i c e s , Department of National Defence, in the development of a suitable t e s t f o r compatibility of f i r e -fighting f o a m s with d r y powder extinguishing agents. T h i s p r o b l e m a r i s e s b e c a u s e of the p r a c t i c e of the Royal Canadian A i r F o r c e i n
following initial control of a c r a s h f i r e by m e a n s of d r y powder with a n application of foam. It h a s been found that t h e d r y powder m a y produce a c c e l e r a t e d breakdown of t h e foam with consequent i n t e r f e r e n c e i n the control of the f i r e .
A t e s t p r o c e d u r e h a s been developed and evaluated, and t h i s work is now r e p o r t e d . The author is a chemical engineer and a r e s e a r c h officer with the F i r e Section of t h e Division i n c h a r g e of work on f i r e extinguishment.
Ottawa, J u l y 1962.
N. B. Hutcheon, A s s i s t a n t D i r e c t o r .
PERFOKMANCE TEST ON FOAM-COMPATIBLE DRY CHEMICAL POWDERS
by K. Sumi
T h e u s e of d r y c h e m i c a l extinguishing powder in conjunction with m e c h a n i c a l foam a g a i n s t a i r c r a f t c r a s h f i r e s i s a common technique employed by t h e Royal Canadian A i r F o r c e . D r y c h e m i c a l powder
p r o v i d e s a m e a n s f o r r a p i d "knock-down1' of f l a m m a b l e liquid f i r e s when applied a t a p r o p e r r a t e and could be u s e d during r e s c u e of p e r s o n n e l involved i n a i r c r a f t f i r e s . Dry c h e m i c a l powder d o e s not, however, p r o t e c t the f l a m m a b l e liquid f r o m r eignition. Mechanical foam is u s u a l l y u s e d , t h e r e f o r e , in conjunction with d r y c h e m i c a l
powder t o complete t h e extinguishment of such a f i r e . Under o p e r a t i o n a l conditions w h e r e a f l a m m a b l e liquid f i r e s u c h a s t h a t due t o a i r c r a f t c r a s h i s to be extinguished by f o a m , following a t t a c k with d r y c h e m i c a l powder, p r o b l e m s of compatibility of foam and d r y powder a r i s e .
S e r i o u s breakdown of foam can be caused by s o m e d r y c h e m i c a l powder, e s p e c i a l l y by t h o s e containing a m e t a l l i c s t e a r a t e (1, 2, 3 ) .
In r e c e n t y e a r s , foam -compatible d r y c h e m i c a l p o w d e r s have been developed and a n u m b e r of b r a n d s a r e now c o m m e r c i a l l y available. The Inspection S e r v i c e s of t h e Department of National Defence r e q u e s t e d the National R e s e a r c h Council t o conduct s t u d i e s d i r e c t e d t o w a r d the development of a p e r f o r m a n c e t e s t to e n s u r e a c e r t a i n d e g r e e of foam compatibility of d r y c h e m i c a l extinguishing powder f o r f u t u r e p r o c u r e m e n t s . A t e s t method devised in compliance with t h i s r e q u e s t and a l i m i t e d n u m b e r of e x p e r i m e n t a l r e s u l t s a r e given in t h i s r e p o r t .
TESTS FOR FOAM -COMPATIBLE DRY CHEMICAL POWDER
T h e need f o r a s t a n d a r d t e s t p r o c e d u r e f o r evaluating d r y c h e m i c a l powders on t h e question of compatibility with f o a m h a s a l s o been r e c o g n i z e d i n other c o u n t r i e s . Studies on t h i s problem have been
c a r r i e d out a t the
U.
S. Naval R e s e a r c h L a b o r a t o r y ( 2 ,3 ,
4,5)
and t h e Joint F i r e R e s e a r c h Organization of t h e United Kingdom ( 1 ) . P e r-
f o r m a n c e t e s t s which a r e c l o s e l y r e l a t e d t o t h e p r e s e n t investigation h a v e been developed by two o r g a n i z a t i o n s ; a b r i e f r e v i e w of t h e s e t e s t s follows.1. D r a f t Specification f o r F o a m -Compatible D r y P o w d e r of t h e M i n i s t r y of W o r k s , G r e a t B r i t a i n
(6).
One-half pound of powder i s d i s t r i b u t e d evenly o v e r t h e s u r f a c e of 5 gallons of g a s o l i n e contained i n a tray- 3 ft in d i a m e t e r and 4 in. deep. A f t e r a p r e - b u r n p e r i o d of one m i n u t e , foam m a d e by a v a r i a b l e f o a m g e n e r a t o r i s d i s c h a r g e d t h r o u g h a 9/32 in. d i a m e t e r n o z z l e l o c a t e d 8 ft f r o m t h e c e n t r e of t h e f i r e and 4 ft above the f u e l s u r f a c e . T h e f o a m
s t r e a m i s d i r e c t e d i n t o t h e c e n t r e of t h e t r a y . F o a m of expansion 8 and c r i t i c a l s h e a r i n g s t r e s s of 400 d y n e s / s q c m i s applied a t 'a r a t e of 0. 35 gallon of f o a m liquid p e r m i n u t e , i. e . , 0. 07 g p m / s q ft. T h e f i r e is c o n s i d e r e d t o b e "controlled" when i t s r a d i a n t i n t e n s i t y i s r e d u c e d t o 10 p e r cent of i t s i n i t i a l value. The c r i t e r i o n f o r a c c e p t a n c e of d r y c h e m i c a l powder is t h a t t h e t e s t f i r e s h a l l be c o n t r o l l e d i n l e s s than 5 m i n u s i n g t h e powder i n conjunction with f o a m compounds conforming t o M. 0 . W. s p e c i f i c a t i o n .
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 , Inc.
U n d e r w r i t e r s ' L a b o r a t o r i e s , Inc. was engaged i n s t u d i e s t o develop a f o a m c o m p a t i b i l i t y t e s t f o r . d r y c h e m i c a l extinguishing powder when t h e p r e s e n t i n v e s t i g a t i o n w a s initiated a t t h e National R e s e a r c h
Council. T h e d e t a i l s of t h e t e s t method d e s c r i b e d below a r e not c o m p l e t e b e c a u s e t h e p r o c e d u r e had not b e e n finally e s t a b l i s h e d a t t h e t i m e of t h e l a s t c o m m u n i c a t i o n with t h i s o r g a n i z a t i o n .
T e s t s w e r e conducted t o p r o v i d e i n f o r m a t i o n on p o s s i b l e m e t h o d s of evaluating t h e f o a m c o m p a t i b i l i t y a s p e c t of d r y c h e m i c a l powder. The r e s u l t s of s o m e of t h e s e s t u d i e s h a v e b e e n r e p o r t e d ( 7 ) .
T h e t e s t s w e r e conducted on a s i m u l a t e d s p i l l f i r e , u s i n g a thin l a y e r of w a t e r in t h e bottom of a t e s t pan s u p p o r t i n g a t h i n l a y e r of
s t o v e and lighting naphtha. A f t e r a p r e - b u r n ~ e r i o d of 30 s e c o n d s , t h e f i r e w a s extinguished with a d r y c h e m i c a l e x t i n g u i s h e r . All t h e e x -
tinguishing agent w a s d i s c h a r g e d i n t o t h e pan. T h e f i r e w a s then reignited a t one m i n u t e f r o m t h e s t a r t of t h e t e s t . After a n a d d i t i o n a l p r e - b u r n of 1 5 s e c o n d s , f o a m w a s applied t h r o u g h a " s t a n d a r d " f o a m p r o d u c i n g nozzle.
T e s t s w e r e conducted u s i n g p a n s of 10, 15 and 2 0 s q f t . T h e r e q u i r e m e n t f o r f o a m - c o m p a t i b l e d r y c h e m i c a l powder c o n s i d e r e d f o r adoption w a s t h a t "the t e s t f i r e s on which d r y c h e m i c a l h a s
been applied i n a n y amount s h a l l b e capable of being extinguished by any foam conforming to U n d e r w r i t e r s 1 L a b o r a t o r i e s S t a n d a r d s a t a r a t e of 0. 4 U . S. g p m / s q ft. "
EXPERIMENTAL DETAILS
A t e s t p r o c e d u r e was devised t o evaluate t h e d e g r e e of compatibility of d r y c h e m i c a l powders with m e c h a n i c a l foam.
1. Method
Two gall.ons of heptane, t h e volume equivalent t o a 2-in. l a y e r , was floated on an equal volume of w a t e r in a s t e e l f i r e t a n k 2 ft by 2 ft by 1 ft deep. F o u r pounds of d r y c h e m i c a l powder w e r e d i s t r i b u t e d by hand a s evenly a s p o s s i b l e over t h e s u r f a c e of heptane contained in the f i r e tank, except in the c a s e of blank d e t e r m i n a t i o n s in which no powder was used.
After a p r e - b u r n p e r i o d of one m i n u t e , foam having a n expansion rati'o of 10 with a 25 p e r cent d r a i n a g e t i m e of about 3 m i n u t e s , produced by a v a r i a b l e foam g e n e r a t o r ( 8 ) was d i s c h a r g e d into t h e c e n t r e of t h e t a n k through a 1/2 -in. nozzle a t a solution r a t e of application of 0. 1 gpm p e r
s q u a r e foot of fuel s u r f a c e . T h e nozzle was supported d i r e c t l y above the c e n t r e of t h e tank
3
ft above the fuel level. The p r o g r e s s in s u p p r e s s i o n of f i r e w a s r e c o r d e d by m e a n s of a gold-disc r a d i o m e t e r (10) connected t o a millivolt r e c o r d e r . T h e r a d i o m e t e r w a s located 6 f t f r o m one s i d e of t h e tank and 2 ft above i t s upper edge. Control t i m e and extinguishment t i m e w e r e r e c o r d e d for e a c h determination. Control t i m e i s defined a s t h e t i m e a f t e r the s t a r t of foam application a t which the r a d i a t i o n i n t e n s i t y f r o m t h e f i r e i s d e c r e a s e d t o 10 p e r cent of t h e m a x i m u m value attained during t h e p r e - b u r n period. Extinguishment t i m e i s defined a s the t i m e a f t e r the s t a r t of foam application a t which the l a s t f l i c k e r of f l a m e is eliminated.2. F o a m Liquids and Dry C h e m i c a l Extinguishing Agents
Seven b r a n d s of "6 p e r cent R e g u l a r " m e c h a n i c a l foam liquid, four b r a n d s of "compatible" d r y c h e m i c a l powder and one b r a n d of "standard" d r y c h e m i c a l powder w e r e used in t h e p r e s e n t s e r i e s of e x p e r i m e n t s .
3.
R e s u l t sf o r a l l the combinations of f o a m liquids and d r y c h e m i c a l extinguishing p o w d e r s examined a r e given in T a b l e s I A and I B r e s p e c t i v e l y . R e s u l t s
of blank d e t e r m i n a t i o n s a l s o in duplicate for t h e s e v e n b r a n d s of foam liquid a r e included in t h e s e T a b l e s .
4. Discussion
( a ) T h e Method
A number of a r b i t r a r y decisions had t o be m a d e in e s t a b l i s h i n g t h e t e s t p r o c e d u r e d e s c r i b e d above. Some explanation of t h e s e i s in o r d e r
.
P r e v i o u s s t u d i e s on f i r e extinguishment t e s t s of m e c h a n i c a l f o a m indicated t h a t the t e s t developed using a 2 - by 2-ft t a n k i s a s adequate t o a s c e r t a i n t h e quality of foam liquid a s one u s i n g a 10- by
10-ft tank. T h u s t h e r e was r e a s o n t o believe that a 2 - by 2 -ft tank would be useful f o r examining t h e d e g r e e of compatibility between different combinations of foam liquids and d r y c h e m i c a l extinguishing p o w d e r s . A 2 - by 2-ft by 1 -ft deep s t e e l f i r e tank was s e l e c t e d f o r t h e p r e s e n t investigation.
F o u r pounds of d r y c h e m i c a l powder (i. e . , 1 l b p e r s q ft of fuel s u r f a c e ) was used in t h e p r e s e n t investigation, except f o r blank d e t e r m i n a t i o n s in which no powder was used. T h e quantity of powder s e l e c t e d for u s e i n t h e p r e s e n t s t u d i e s i s in c l o s e a g r e e m e n t with that suggested by U n d e r w r i t e r s ' L a b o r a t o r i e s , Inc. T h e quantity given in t h e d r a f t specification of M i n i s t r y of Works i s c o n s i d e r a b l y l e s s , about 0. 07 lb p e r s q ft of fuel s u r f a c e . T h e quantity of 1 l b p e r s q ft i s c o n s i d e r e d m o r e r e p r e s e n t a t i v e of quantities of p o w d e r s used during a i r c r a f t c r a s h f i r e fighting o p e r a t i o n s of t h e RCAF.
P r e l i m i n a r y e x p e r i m e n t s indicated that a foam solution application r a t e of 0. 1 gpm p e r s q u a r e foot of fuel s u r f a c e would be
s a t i s f a c t o r y for t h e p r e s e n t method in which t h e quantity of powder u s e d is 1 l b p e r s q ft of fuel s u r f a c e . A s m a l l e r solution r a t e of application ( e . g . , 0. 05 gpm p e r s q u a r e foot) was found t o be insufficient f o r llcontrolling" the f i r e using sodium bicarbonate. On the other hand a g r e a t e r solution r a t e of application ( e . g.
,
0. 15 gpm p e r s q u a r e foot) showed l i t t l e d i f f e r e n c e in r e s u l t s between t h o s e in which sodium b i c a r b o n a t e was used a s c o m p a r e d t o t h o s e in which "standard" d r y c h e m i c a l was used.( b ) R e s u l t s
-
rnearls for evaluating the d e g r e e of compatibility between different combinations of foam liquids and d r y c h e m i c a l p o w d e r s . 'They a l s o indicate that "contr 01" t i m e yields h e t t e r replication than extinguishment t i m e . T h e r e f o r e , the i n t e r p r e t a t i o n of t e s t r e s u l t s which follows will be b a s e d on c o n t r o l t i m e .
The m e a n control t i m e s for a l l foam liquids w e r e computed, and a r e shown in T a b l e I I . T h e f i g u r e s in T a b l e I I indicate t h a t foarn- con.patible powders examined have l e s s tendency t o b r e a k down m e c h a n i c a l foam than the "standard" powder examined. The compatible p o w d e r s ,
however, did tend t o b r e a k down foam to s o m e d e g r e e a s s e e n by c o m p a r i s o n with r e s u l t s in which no powder was u s e d . According t o t h e p r o c e d u r e
proposed the u s e of the "standard" d r y c h e m i c a l i n c r e a s e d t h e c o n t r o l t i m e by a f a c t o r of 3 to 4 ( a s compared t o the blank d e t e r m i n a t i o n s ) while the "compatible" powders examined i n c r e a s e d the control t i m e by 14 t o
4 3 p e r cent.
T h e m e a n control t i m e for a l l t h e compatible powders taken together i s given in T a b l e 111. The i n c r e a s e in the c o n t r o l t i m e over blank d e t e r m i n a t i o n for the s e v e n b r a n d s of foam liquid v a r i e d f r o m 5 t o
59
p e r cent. T a b l e I11 i n d i c a t e s t h e r e l a t i v e d e g r e e of compatibility of different foam liquids with the four "compatible" powders examined.T a b l e I A indicates t h a t a single determina'tion o r even duplicate d e t e r m i n a t i o n , which i s d e s i r a b l e for specification p u r p o s e s , could give m i s l e a d i n g r e s u l t s . A p o s s i b l e explanation for t h i s behaviour i s a s follows. A t e s t p r o c e d u r e in which s u p p r e s s i o n o c c u r s in a n efficient m a n n e r t e n d s t o yield good replication. T h i s type of t e s t i s not suitable for examining the r e l a t i v e d e g r e e of compatibility of different combinations of m e c h a n i c a l f o a m liquid and d r y c h e m i c a l w h e r e i t i s d e s i r e d t o d i f f e r e n t i a t e between good combinations and poor combinations, T h e t e s t method s e l e c t e d for t h e p r e s e n t s t u d i e s was t h e r e f o r e one that i s not v e r y efficient for s u p - p r e s s i o n . When t h e foam i s f i r s t applied t h e r e i s s o m e doubt a s t o whether s u p p r e s s i o n will t a k e p l a c e . Once the f o a m i s built up t o a
c e r t a i n s t a g e , s u p p r e s s i o n u s u a l l y t a k e s p l a c e in an o r d e r l y m a n n e r . T h e t i m e taken t o build up the quantity of foam n e c e s s a r y for o r d e r l y s u p p r e s s i o n t o occur i s not v e r y r e p r o d u c i b l e b e c a u s e of the m a n y v a r i a b l e s p r e s e n t in a f i r e t e s t .
Some c a u s e s of t h i s condition a r e the unsteady behaviour of f i r e and the v a r i a t i o n in the mixing of t h e powder with the foam. T h u s , i t is not s u r p r i s i n g t o find v a r i a t i o n s in r e s u l t s of r e p l i c a t e t e s t s . Replication i s p o o r e s t w h e r e t h e s u p p r e s s i o n i s l e a s t efficient, i. e . , when t h e s t a n d a r d d r y c h e m i c a l was used.
CONCLUSION T h e p e r f o r m a n c e t e s t d e v i s e d i n t h e p r e s e n t i n v e s t i g a t i o n a p p e a r s t o p r o v i d e a r e a s o n a b l e m e a n s f o r e v a l u a t i n g t h e d e g r e e of c o m p a t i b i l i t y b e t w e e n d i f f e r e n t c o m b i n a t i o n s of d r y c h e m i c a l p o w d e r a n d
mechanical
f o a m liquid. S o m e v a r i a t i o n in r e s u l t s of r e p e a t t e s t s a p p e a r s t o b e u n a v o i d a b l e a s t h i s i s i n h e r e n t i n a p e r f o r m a n c e t y p e t e s t s u c h a s t h e one u s e d . T h e e x p e r i m e n t s p r o v i d e r e s u l t s which could b e i n t e r p r e t e d on a s t a t i s t i c a l b a s i s . H e n c e , one should b e c a u t i o u s of r e a c h i n g c o n - c l u s i o n s on t h e b a s i s of a s m a l l n u m b e r of d e t e r m i n a t i o n s . T h e a u t h o r w i s h e s t o t h a n k M e s s r s . C. W o l f g r a m a n d A. C r o o k of t h e DBR F i r e R e s e a r c h S e c t i o n f o r conducting t h e e x p e r i m e n t s . R E F E R E N C E S 1. H i r d , D. a n d M. J . G r e g s t e n . T h e e f f e c t of d r y p o w d e r on t h e e f f i c i e n c y of m e c h a n i c a l f o a m . F i r e P r o t e c t i o n R e v i e w , Vol. 19, 1956, p. 473. 2. P e t e r s o n , H. B. and R . L . T u v e . E f f e c t s of f i r e e x t i n g u i s h i n g d r y c h e m i c a l s ( b i c a r b o n a t e b a s e ) on m e c h a n i c a l f o a m b l a n k e t s . U. S. N a v a l R e s e a r c h L a b o r a t o r y l t r . R e p o r t 3250-
72/49, J u n e 1949, 5p. 3. P e t e r s o n , H. B. E f f e c t s of f i r e e x t i n g u i s h i n g d r y c h e m i c a l s ( b i c a r b o n a t e b a s e ) on m e c h a n i c a l f o a m b l a n k e t s-
r e s u l t s of f u r t h e r i n v e s t i - g a t i o n s . U. S. N a v a l R e s e a r c h L a b o r a t o r y l t r . R e p o r t 3250-
2 9 ~ / 5 2 , F e b . 1952, 6p. 4. P e t e r s o n , H. B. e t al. T h e d e v e l o p m e n t of n e w f o a m-
c o m p a t i b l e d r y c h e m i c a l f i r e e x t i n g u i s h i n g p o w d e r s . U, S. N a v a l R e s e a r c h L a b o r a t o r y R e p o r t 4986, Sept. 1957, 27p. 5. J a b l o n s k i , E. J. a n d R . L. Gipe. A new m e t h o d f o r d e t e r m i n i n g t h e d e g r e e of c o m p a t i b i l i t y of d r y c h e m i c a l ~ o w d e r s with m e c h a n i c a l f o a m s . U. S. Naval R e s e a r c h L a b o r a t o r y R e p o r t 5329, June 1959, 14p. 6. H i r d , D. P r i v a t e c o m m u n i c a t i o n , M a r c h 3, 1961. 7. J e n s o n , R. S u b j e c t 299. F o a m - c o m p a t i b l e d r y - c h e m i c a l e x t i n g u i s h e r s . U n d e r w r i t e r s t L a b o r a t o r i e s I n c . , A p r i l 12, 1961 and J u n e 1. 1961.8. Sumi,
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9. Sumi,
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S m a l l - s c a l e f i r e extinguishment t e s t on mechanical foam. P a r t I I.
National R e s e a r ch Council, Division of Building R e s e a r c h , Internal R e p o r t No. 230, Ottawa, Sept. 1961.0. McGuire, J. H. and H. Wraight. Radiometer for field u s e . J o u r n a l of Scientific I n s t r u m e n t s , Vol. 37, April 1960, p. 128.
TABLE I A
CONTROL TIME, MINUTES
P o w d e r s N o P o w d e r S t a n d a r d C o m p a t i b l e No. 1 Compatible No. 2 Compatible No. 3 Compatible No. 4 1
*
T h i s m e a n i s computed u s i n g t h e v a l u e of 4 . 0 0 i n s t e a d of g r e a t e r t h a n 4. 00. F o a m Liquids D R u n 1 0. 55 2. 0 0 0 . 8 3 0 . 9 2 1 . 0 0 1 . 2 2 E C A Run 2 0 . 6 3 1. 25 0. 70 0 . 9 2 0 . 8 0 1. 17 B Mean 0. 59 1. 6 2 0, 7 6 0 . 9 2 0 . 9 0 1 . 2 0 M e a n 0. 5 4 2. 00 0. 7 9 0 . 7 6 0 . 7 0 0 . 6 8 Run 1 0. 57 2. 35 0. 68 0 . 7 5 0 . 7 2 0 . 6 8 I F Rur, 1 0 . 6 0 1. 2 0 0. 6 0 0. 67 0. 77 0. 6 0 Mean 0 . 5 4 1. 38 0. 58 0. 6 6 0 . 6 8 0. 6 4 Mean 0 . 5 8 1. 9 1 0. 62 0. 6 5 0. 7 0 0 . 9 6 Run . 1 0 . 5 2 2. 0 0 0. 57 0. 7 0 0. 7 0 0. 62 Run 1 0 . 6 0 2. 27 0. 6 5 0. 6 7 0. 68 1. 03 Run 2 0. 52 1. 6 5 0. 9 0 0 . 7 7 0 . 6 7 0.67 Run 1 0. 53 1 . 8 7 0. 60 0 . 6 0 0 . 6 0 0 . 6 8 G R u n 2 0 . 5 7 0. 7 5 0. 58 0. 6 3 0 . 6 5 0 . 6 5 R u n 2 0 . 5 7 1. 55 0. 6 0 0. 6 3 0. 72 0.88 Run 1 0. 6 3 >4. 0 0 0. 7 0 0 . 5 3 0 . 9 8 1. 1 3 Run 2 0 . 6 2 0. 6 5 0. 6 3 0. 6 0 0. 62 0. 57 Run 2 0. 62 2. 6 8 0. 6 5 0 . 6 7 0 . 6 5 0. 57 Mean 0 . 6 1 0. 9 2 0. 62 0. 6 4 0. 70 0. 58 M e a n 0. 58 2. 28 0. 62 0 . 6 4 0.62 0 . 6 2 R u n 2 0 . 6 3 2. 50 0. 58 0 . 6 7 1.03 1. 10 M e a n 0 . 6 3 9 3. 2 5 0. 6 4 0 . 6 0 1 . 0 0 1. 1 2T A B L E I B E X T I N G U I S H M E N T T I M E , M I N U T E S F o a m L i q u i d s
*
T h i s m e a n is c o m p u t e d u s i n g t h e v a l u e of 4. 00 i n s t e a d of g r e a t e r t h a n 4. 00. A B D C R u n 1 0 . 6 8 2. 27 1. 12 1. 48 1. 12 1. 3 3 M e a n 0 . 9 5 1 . 7 5 1. 58 1. 0 4 1. 08 1. 28 R u n 1-
-
-
-
-1. 17 3 . 6 7 0. 8 7 0. 9 3 1. 1 3 0. 7 7 R u n R u n M e a n R u n 2 2 E No P o w d e r S t a n d a r d C o m p a t i b l e No. 1 C o m p a t i b l e No. 2 C o m p a t i b l e No. 3 C o m p a t i b l e No. 4 R u n 2 0 . 7 2 2. 40 2. 52 1. 08 1. 20 1. 3 3 R u n 1 0 . 6 3 )4. 00 1. 3 3 2. 0 0 1. 50 0. 9 7 R u n 2 3 . 0 0 3. 1 3 0. 8 80.
7 5 0. 9 5 0. 68 M e a n 0 . 7 0 2. 3 4 1. 8 2 1. 28 1. 1 6 1. 3 3 F M e a n 2. 0 8 3. 40 0. 8 8 0. 8 4 1. 0 4 0. 7 2 1. 6 3 7 4 . 0 0 1. 5 5 3. 00 0. 8 5 1. 3 3 R u n 1 0 . 8 7 2 . 0 0 0. 6 5 0. 7 0 0. 6 2 0. 8 3 R u n 2 0 . 6 0 3 . 6 7 1. 38 1. 40 0. 8 7 0. 8 2 G = M e a n 0 . 6 2 >: 3 . 8 4 1. 36 1. 7 0 1. 1 8 0. 9 0 R u n 1 1 . 0 0 >4. 00 2. 37 0. 6 3 1. 17 2. 5 3 1. 3 3 1 . 7 3 0. 6 7 0. 9 3 0. 8 5 1. 1 8 R u n 2 0 . 6 5 3 . 0 7 0. 8 0 0. 8 0 0. 7 2 0. 8 0 M e a n 0 . 7 6 2. 5 4 0. 7 2 0. 7 5 0 . 6 7 0. 8 2 R u n 2 1 . 4 3 2 . 9 5 1. 79 0. 8 0 1. 37 1 . 2 3 1 . 4 8 2 . 8 6 1. 1 1 1. 96 0. 8 5 1. 2 6 M e a n 1 . 2 2*
3. 48 2. 08 0. 7 2 1. 27 1. 8 8 1. 20 2. 50 1. 07 1. 00 1. 17 0. 8 3 0 . 7 0 1 . 0 0 2. 08 1. 08 1. 00 1. 7 2T A B L E I 1
MEAN CONTROL TIME FOR FOAM LIQUIDS
T A B L E I 1 1
MEAN CONTROL TIME FOR "COMPATIBLE" POWDERS P o w d e r s No P o w d e r S t a n d a r d Compatible No. 1 Compatible No. 2 Compatible No. 3 Compatible No, 4 All f o a m liquids Sum of m e a n s 4. 07 13. 36 4. 6 3 4. 87 5. 30 5. 8 0 All Compatible P o w d e r s F o a m Liquids S u m o f m e a n s Sum of m e a n s f 4
Sum of m e a n s
T
no. of f o a m liquids0. 58 1.
