Radiation conditions: dwelling house fire

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Radiation conditions: dwelling house fire

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NATIONAL RESEARCH COUNCIL CANADA

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

RADIATION COITDITIONS : DWELIJTNG HOUSE F I R E by J. H. M c G u i r e I n t e r n a l R e p o r t No. 222 o f t h e

D i v i s i o n o f

Building R e s e a r c h OTTAWA May 1 9 6 1

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PREFACE Examinations

a t

t h e s i t e s of a c t u a l f i r e s do n o t always provide u s e f u l i n f o r m a t i o n b u t o c c a s i o n a l l y c a s e s can be r e c o g n i z e d which a r e amenable t o a n a l y s i s c a p a b l e of producing w o ~ t h w h i l e r e s u l t s . One such c a s e c a p a b l e of p r o v i d i n g a d d i t i o n a l i n f o r m a t i o n on t h e i g n i t i o n of one house from a n a d j a c e n t house on f i r e i s now a n a l y s e d

and r e p o r t e d . The a u t h o r i s a p h y s i c i s t and a r e s e a r c h o f f i c e r w i t h t h e F i r e Research S e c t i o n of t h e D i v i s i o n engaged i n s t u d i e s of s p r e a d of f i r e .

Ottawa

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RADIATION CONDITIONS: DWELLING HOUSE FIRE

by

J . H. McGuire

On 1 5 March 1960 a f i r e o c c u r r e d i n t h e u p p e r s t o r y o f a d u p l e x d w e l l i n g house i n O t t a w a . I t w a s c h a r a c t e r i z e d by a v e r y r a p i d development which was p r o b a b l y a s s o c i a t e d w i t h a s m a l l q u a n t i t y o f g a s o l i n e a n d w i t h c o m b u s t i b l e w a l l l i n i n g s . F i r e Department a p p a r a t u s a r r i v e d w i t h i n a few m i n u t e s of t h e o u t b r e a k and e x t i n g u i s h e d

i t

b e f o r e t h e whole o f t h e b u i l d i n g became i n v o l v e d . N e v e r t h e l e s s t h e c o m b u s t i b l e s i d i n g o f t h e a d j a c e n t house i g n i t e d a n d it i s w i t h t h i s f a c e t of t h e i n c i d e n t t h a t t h i s r e p o r t i s c o n c e r n e d . The r e l a t i v e d i s p o s i t i o n s of t h e two h o u s e s a n d o f t h e windows a n d o t h e r o p e n i n g s i n v o l v e d a r e i l l u s t r a t e d i n F i g s . 1 t o

3.

The f i r e o r i g i n a t e d i n t h e room a s s o c i a t e d

w i t h windoa A1 ( F i g . 2 ) a n d w i t h i n a s h o r t time i t enveloped t h e whole o f t h e u p p e r s t o r y .

The damage t o t h e s i d e of house B i s i l l u s t r a t e d i n F i g .

3.

The i m i t a t i o n s t o n e s i d i n g t o w a r d s t h e f r o n t h a l f of t h e house u n d o u b t e d l y i g n i t e d , p r o b a b l y i n t h e v i c i n i - $ y of window B1. I h e o n l y woodwork t h a t showed e v i d e n c e of h a v i n g i g n i t e d was t h e s i l l o f window B2 and

it

w a s o b v i o u s t h a t i g n i t i o n h a d r e s u l t e d n o t from r a d i a t i v e h e a t i n g b u t from b u r n i n g d r o p s o f bitumen which had f a l l e n o n t o t h e

s i l l from above. The u p p e r p o r t i o n o f t h e i m i t a t i o n s t o n e s i d i n g t o t h e r e a r o f t h e s i d e o f house B w a s s e v e r e l y damaged b u t

it

i s n o t l i k e l y t h a t it w a s d i r e c t l y i n v o l v e d i n f i r e . The damage t o t h e l o w e r p o r t i o n o f t h e r e a r o f t h e s i d e o f h o u s e B , i l l u s t r a t e d i n F i g s .

3

a n d 5 , i s i n t e r e s t i n g i n t h a t

it

d e m o n s t r a t e s v e r y s i m p l y t h a t t h e p r i m a r y mechanism of h e a t t r a n s f e r t o t h i s r e g i o n was r a d i a t i v e . !The damage t o t h e p a i n t on t h e door i l l u s t r a t e d i n F i g . 5 d i d n o t r e s u l t from t h e f i r e e x p o s u r e .

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Comparison w i t h P r e v i o t r s F i n d i n g s The I g n i t i o n o f b u i l d i n g s by r a d i a t i o n h a s been c o n s i d e r e d p r e v i o u s l y by t h e D i v i s i o n o f B u i l d i n g R e s e a r c h (1, 2,

3 )

and it i s i n t e r e s t i n g t o compare t h e f i n d i n g s a n d recommendations c o n t a i n e d i n t h e t h r e e r e f e r e n c e s l i s t e d w i t h t h e c i r c u m s t a n c e s o f t h e f i r e d i s c u s s e d i n t h i s r e p o r t . S i n c e t h e o n l y m a t e r i a l on t h e s i d e o f h o u s e B t h a t was i g n i t e d a s a r e s u l t o f r a d i a t i v e h e a t t r a n s f e r was i m i t a t l o n s t o n e s i d i n g , which i s n o t m e n t i o n e d i n t h e t h r e e p r e v i o u s r e p o r t s , it i s f i r s t n e c e s s a r y t o h a v e a knowledge o f i t s c h a r a c t e r i s t i c s . Using a o n e - f o o t - s q u a r e g a s - f i r e d r a d i a n t p a n e l a s t h e s o u r c e o f r a d i a t i o ~ ~ ,

i t

w a s f o u n d t h a t t h e c r i t i c a l i n t e n s i t y n e e d e d t o p r o d u c e t h e p i l o t i g n i t i o n * o f i m i t a t i o n b r i c k s i d i n g , which i s v i r t u a l l y i d e n t i c a l t o i m i t a t i o n s t o n e s i d i n g , w a s 0 . 2 4 cal/cm2/sec. When b u i l d i n g s e p a r a t i o n recommendations w e r e b e j n g f o r m u l a t e d , t h e l e v e

₃

of r a d i a t i o n t o b e g u a r d e d a g a i n s t w a s t a k e n a s 0.3 cal/cm / s e c below which t h e p i l o t i g n i t i o n o f wood d o e s n o t o c c u r .

B e a r i n g i n mind t h a t f i e l d c o n d i t i o n s would p r o b a b l y r e q u i r e a h i g h e r c r i t i c a l i n t e n s i t y f o r i g n i t i o n t h a n would l a b o r a t o r y c o n d i t i o n s , o v ~ i n g , f o r example, t o v o l a t i l e d i l u t i o n by l i g h t w i n d s , v e r y l i t t l e e r r o r i s i n v o l v e d i n t a k i n g t h e v a l u e o f 0.3 cal/cm2/sec, u s e d i n p r e v i o u s c a l c u l a t i o n s , as t h e minimum l e v e l t h a t w a s n e e d e d t o p r o d u c e t h e i g n i t i o n o f t h e i m i t a t i o n s i d i n g o f h o u s e B. BVO c l a s s e s of b u r n i n g b u i l d i n g were c o n s i d e r e d i n t h e p r e v i o u s work; d w e l l i n g A , d i s c u s s e d i n t h e p r e s e n t r e p o r t , f a l l s i n t h e " p a r t i c u l a r l y h a z a r d o u s" _{c a t e g o r y s i n c e}

it

i n c l u d e d a s u b s t a n t i a l p r o p o r t i o n o f flammable l i n i n g s . The e x t e r i o r u p s t a i r s d o o r i . . ~ llzouse A

(Tig.

4 ) w a s c l o s e d d u r i n g t h e e a r l y s t a g e s o f t h e f i r e a n d h e n c e window A w a s

1 t h e o n l y s u b s t a n t i a l o p e n i n g i n t h e s i d e of h o u s e A a.t t h e t i m e h o u s e B i g n i t e d . This f i n d i n g i s c o n f i r m e d b y t h e f a c t t h a t i g n i t i o n o f t h e s i d e o f h o u s e B o n l y o c c u r r e d i n t h e r e g i o n o f window Bl. Had t h e d o o r i n q u e s t i o n been d e s t r o y e d b e f o r e t h e f i r e d e p a r t x e n t g a i n e d c o n t r o l o f t h e f i r e t h e f l a m i n g from t h i s a r e a , t o g e t h e r w i t h t h a t from window A p ,

P i l o t . g n i t i o n i n v o l v e s a s ~ i a l l h i g h t e m p e r a t u r e i g n i t i o n soilrce which p l a y s no p a r t i n t h e h e a t i n g o f t h e s o l i d m a t e r i a l b u t s e r v e s t o i g n i t e t h e d i s t i l l e d v o l a t i l e s when t h e s e a r e e v o l v e d a t a s u f f i c i e n t r a t e t o g i v e a flammable a t m o s p h e r e n e a r t o t h e specimen. D u r i n g t h e e x p e r i m e n t a l p r o c e d u r e a s m a l l p i l o t f l a m e a few i n c h e s a b o v e t h e s p e c i m e n c o n s t i t u t e d t h e i g n i t i n g s o u r c e . D u r i n g a f i r e , s p a r k s o r f l y i n g b r a n d s w i l l p e r f o r m t h e same f u n c t i o n .

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would have r e s u l t e d i n t h e i g n i t i o n of t h e r e a r h a l f of t h e s i d e o f h o u s e B.

Using t h e same b a s i s of c a l c u l a t i o n a s f o r Table V

i n DBR I n t e r n a l R e p o r t No. 1.87 a n d t a k i n g window A1 a s t h e opening i n v o l v e d , t h e recommended s e p a r a t i o n between t h e two d v r e l l i n g s would be 1 2 f t 6 i n , The s e p a r a t i o n w a s i n f a c t 1 7 f t a n d t h e r e a s o n why i g n i t i o n of house B o c c u r r e d w a s t h a t t h e f i r e i n house A, which i n i t i a l l y i n v o l v e d g a s o l i n e , developed more r a p i d l y t h a n i s customary a n d peak r a d i a t i o n l e v e l s were a t t a i n e d b e f o r e t h e a r r i v a l of t h e f i r e f i g h t i n g a p p a r a t u s . It would n o t be e c o n o m i c a l l y p r a c t i c a l t o

recommend d i s t a n c e s of s e p a r a t i o n which would p r o t e c t b u i l d i n g s a g a i n s t i g n i t i o n by r a d i a t i o n u n d e r a l l circum- s t a n c e s a n d t h o s e g i v e n by DBR Intel-ma1 R e p o r t No. 187

( 3 )

were b a s e d on t h e e x p e r i m e n t a l f i n d i n g t h a t r a d i a t i o n l e v e l s

from f i r e s a r e g e n e r a l l y f a i r l y low i n t h e i n i t i a l s t a g e s . The p r i n c i p l e a d o p t e d w a s t h a t s e p a r a t i o n n e e d o n l y o f f e r p r o t e c t i o n (luring t h i s p e r i o d , a f t e r rillich f i - r e department a c t i o n can a c h i e v e t h e same oh j e c t .

Had s e p a r a t i o n been r e q u i r e d t o g i v e p r o t e c t i o n a g a i n s t t h e peak l e v e l s of r a d i a t i o n t h e s e p a r a t i o n c a l l e d f o r on t h e b a s i s of t h e r e s u l t s o f t h e S t . Lawrence Burns ( 2 ) would have been 1 9 f t 6 i n ,

An i n t e r e s t i n g f e a t u r e of t h e f i r e i n house B i s t h a t t h e f i r e d e p a r t m e n t w a s a b l e t o e x t i n g u i s l l

i t

q u i t e r e a d i l y .

It would t h e r e f o r e seem t h a t t h e ad.option of t h e compromise recommendations g i v e n i n DBR I n t e r n a l R e p o r t No. 187 w i l l

g i v e some measure of p r o t e c t i o n even t o p r o p e r t i e s exposed t o g r e a t e r t h a n normal h a z a r d s .

E f f e c t of Wind

The recommendations g i v e n i n DBR I n t e r n a l R e p o r t No. 187 do n o t , f o r o b v i o u s r e a s o n s , r e l a t e t o wind a s a f a c t o r ;

t h e y were b a s e d on t h e w o r s t c o n d i t i o l l s p r e v a i l i n g d u r i n g %.he t e s t f i r e s c o n s i d e r e d . Although i.t mas d e m o n s t r a t e d , d u r i n g t h e S t . Lawrence Burns, t h a t i n t h e p r e s e n c e of a wind r a d i a t i o n l e v e l s t o l e e w a r d can be much g r e a t e r t h a n r a d i a t i o n

l e v e l s t o windward, i n s u f f i c i e n t r e s u l t s a n d d a t a a r e a v a i l a b l e t o a l l o w t h e d e r i v a t i o n of f u r t h e r c o n c l u s i v e d e d u c t i o n s

o r of q u a n t i t a t i v e r e l a t i o n s h i p s . During t h e O t t a w a f i r e t h e wind s p e e d was appl-oximately

3

_{mph a n d}

_it

_{i s}_a _{m a t t e r}

of c o n j e c t u r e a s t o w h e t h e r a h i g h e r wind v e l - o c i t y i n t h e

a p p r o p r i a t e d i r e c t i o n would have produced s u b s t a n t i a l l y h i g h e r l e v e l s o f r a d i a t i o n . !This does n o t seem v e r y l i k e l y , however,

as t h e r a d i a t i o n l e v e l s a l r e a d y approached t h e h i p h e s t v a l u e s e v e r r e c o r d e d from f i r e s .

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Conclusion !he c i r c u m s t a n c e s a s s o c i a t e d w i t h

the

i g n i t i o n of t h e s i d e of h o u s e B i n d i c a t e t h a t t h e s e p a r a t i o n s recommended i n DBR I n t e r n a l Report No. 187 a r e , a s s t a t e d i n t h e r e p o r t , n o t s u f f i c i e n t t o g i v e complete p r o t e c t i o n a g a i n s t t h e s p r e a d o f f i r e by r a d i a t i o n u n d e r a d v e r s e c o n d i t i o n s . I f , on economic grounds, a b u i l d i n g code w i l l a l l o w some e l e m e n t of r i s k t h e n t h e recommendations s h o u l d be c o n s i d e r e d a c c e p t a b l e . The f a c t t h a t t h e f i r e i n house B was r e a d i l y e x t i n g u i s h e d i s a f u r t h e r i n d i c a t i o n t h a t t h e s e p a r a t i o n recommendations s h o u l d n o t be made more s t r i n g e n t . R e f e r e n c e s 1. S h o r t e r , G.W. a n d J . H . McGuire. S t . Lawrence B u r n s : Summary R e p o r t . N a t i o n a l Research C o u n c i l , 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 , I n t e r n a l R e p o r t No. 1 5 8 , O t t a w a . Dec. 1959.

2. McGuire, J . H . S t . Jawrence Burns : _{Radiometer' Measurements.}

N a t i o n a l Research C o u n c i l , 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 , I n t e r n a l Report No.

153,

Ottawa. Dec, 1959.

3. McGuire, J . H . S p a t i a l S e p a r a t i o n of B u i l d i n g s . N a t i o n a l Research C o u n c i l , D i v i s i o n of B u i l d i n g Research,

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R O A D

1 I

I

B

I

s

I

-4

17'-

0"

11:

-

(HOUSE INVOLVED)

A

PRIMARILY

FIGURE I

PLAN OF HOUSES INVOLVED

-0

0

-

N

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hT

IMITATION S T O N E SIDING, BADLY DAMAGED BY F l R E I M I T A T I O N S T O N E SIDING, M E L T E D BY R A D I A T I O N

I M I T A T I O N S T O N E SIDING, CAUSE O F DAMAGE N O T CERTAIN

PROBABLY M E L T E D BY RADIATION W I T H O U T IGNITING

CRACKED

BROKEN

UNDAMAGED

i

UNDAMAGED CRACKED L w o o D SILL DAMAGED BY FIRE

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P i g u r e

4 :

Rear-side view of House A