St. Lawrence Burns: radiant temperature of openings

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NATIORAL RESEARCH COUNCIL CANADA

D I V I S I O N OF BirTLDING RESEARCH

ST. LAWRENCE BURNS

RADIANT TEMPERATURE O F OPEXINGS by D. G. S t e p h e n s o n R e p o r t N o . 156 o f 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 OTTAWA December 1959

The circumstance:; t h a t l e d t o t h e c a r r y i n g o u t of f i r e t e s t s on e i g h t b u i ' l d i n g s i n t h e p r o j e c t lcnown a s t h e S t . Lawrence Burns, a r l > l t h e o b j e c t i v e s a n d t h e ways i n which t h e s e were achicvtci a r e f u l l y d e s c r i b e d i n a

g e n e r a l r e p o r t . I t c o n s t i t u t e s t h e complete r e c o r d of t h e planning and e x e c u t i o n of t h e experiments, t o ~ e t h e r w i t h

a l l g e n e r a l inforniation. The d e t a i l s on each kind of

measurement made, i n c l u d i n g t h e r e s u l t s o b t a i n e d , a r e con- t a i n e d i n s e p a r a t e companion r e p o r t s of which t h i s i s one.

A l l t h e r e s u l t s a r e combined and a r e d i s c u s s e d and f i n a l c o n c l u s i o n s drawn i n a summary r e p o r t .

D u p l i c a t i o n h a s been avoided a s f a r a s p o s s i b l e , and i t w i l l be n e c e s s a r y t o r e f e r t o t h e g e n e r a l r e p o r t i n r e a d i n g any of t h e o t h e r r e p o r t s i n c l u d i n g t h i s one f o r any i n f o r m a t i o n which i s p e r t i n e n t t o more t h a n one of them. A l i s t i n g o f a l l r e p o r t s on t h e p r o j e c t f o l l o w s t h i s p r e f a c e .

Tho p a r t i c i p a t i o n of t h e B r i t i s h J o i n t F i r e

Research Organization i n t h e experiment, t h e i n t e r e s t and s u p p o r t of t h e Federal C i v i l Defence a u t h o r i t i e s , t h e a s s i s t a n c e of t h e O n t a r i o F i r e Marshal and h i s s t a f f , and f i n a l l y t h e complete c o - o p e r a t i o n and v e r y c o n s i d e r a b l e a s s i s t a n c e extended by t h e Hydro-Xlectric Power Commission of O n t a r i o a r e a l l g r a t e f u l l y acknowledged. I t i s

a

p l e a s u r e a l s o t o be a b l e t o r e c o r d t h e s p e c i a l c o n t r i b u t i o n made by members of t h e s t a f f of t h e F i r e S e c t i o n who worked l o n g h o u r s , o f t e n under t r y i n g f i e l d c o n d i t i o n s and a t g r e a t p e r s o n a l inconvenience, t o meet t h e many d e a d l i n e s and t o complete t h e p r o j e c t i n a most s a t i s f a c t o r y manner.

The a u t h o r of t h i s r e p o r t i s D r . D. G. Stepheneon, r e s e a r c h o f f i c e r w i t h t h e B u i l d i n g S e r v i c e s S e c t i o n of

t h i s D i v i s i o n , who a s s i s t e d t h e F i r e S e c t i o n i n t h i s p r o j e c t by a r r a n g i n g f o r and a n a l y s i n g t h e r e a d i n g s of r a d i a n t temperature of window openings.

Ottawa

REPORTS ON THE ST. LA~"lRBIlTCE BURRS

-

--

Sub-Tit13 Author

General Report G. 1.V. S h o r t e r

Smoke and Sowid Nea s u r e n e n t s _{G. Williams-Leir}

Temperature Idea surement s G. JJ!illiams-Leir

Radiometer Measurements J . H . McGuire

V e n t i l a t i o n Rate Measurements J . H . I~IcGuire Resis-tance Thermometer

Measurements J . H . McGuire

Radiant Temperature of Openings D. G. Stephenson

Gas A n a l y s i s J . R . J u t r a s

Summary R e p o r t G. W. S h o r t e r and

S T . LA!O3ENCE BURNS R A D I A N T

TEMPERATURE

_{OF OPENINGS}

D.G.

Stephenson S i n c e a b u r n i n g b u i l d i n g can i g n i t e n e i g h b o w i n g s t r u c t u r e s i f t h e r a d i a t i o n r e a c h i n g t h e exposed s u r f a c e 8 i s s u f f i c i e n t l y i n t e n s e , b u i l d i n g codes u s u a l l y s p e c i f y a minimum s e p a r a t i o n between b u i l d i n g s . I t i s p o s s l b l e t o c a l c u l a t e t h e s e p a r a t i o n which i s r e q u i r e d t o p r e v e n t f i r e s p r e a d by r a d i a t i o n i f t h e f o l l o w i n g d a t a a r e a v a i l a b l e : 1. The i n t e n s i t y of t h e r a d i a t i o n e m i t t e d by a b u r n i n g b u i l d i n g ;

2. The r a d i a n t energy f l u x which w i l l i g n i t e t h e exposed wooden p a r t s of a n a d j a c e n t b u i l d i n g .

I A q u i t e complete I n v e s t i g a t i o n of "The I n i t i o n of

Wood by ~ a d i a 1 ; l o n " was made by Lawson a n d Simms

7

l 9 5 2 ) , b u t v e r y few measurements of tho r a d i a t i o n e m i t t e d by a burning b u i l d i n g have been r e p o r t e d . Whon c a l c u l a t i n g t h e e n e r g y whiah may be t r a n s f e r r e d by r a d i a t i o n i t i s common t o assume t h a t t h e openings i n t h e s h e l l of a b u r n i n g b u i l d i n g r a d i a t e a 3

b l a c k b o d i e s a t 1000°C. The v a r i a t i o n i n r a d i a t i o n i n t e n s i t

_%

w i t h time i s normally n o t t a k e n i n t o a c c o u n t , i . e . , t h e 1000 C

i n t e n s i t y i s assumed t o e x i s t long enough f o r t h e exposed s u r f a u e s t o come t o a n e q u i l i b r i u m t e m p e r a t u r e . The S t . Lawrence b u r n s p r o v i d e d a n u s u s u a l o p p o r t u n i t y t o o b t a i n f i e l d measurements of the r a d i a t i o n e m i t t e d b y different t y p e s of b u r n i n g b u i l d i n g s a t v a r i o u s s t a g e s i n t h e development of a f i r e . A r e p r e s e n t a t i v e of t h e J o i n t F i r e Research O r g a n i z a t i o n ( G r e a t ~ r i t a i n ) measured t h e t o t a l r a d i a t i o n i n o i d e n t on a s u r f a c e l o c a t e d

a

known d i s t a n c e from t h e b u r n i n g b u i l d i n g . To supplement h i s r e s u l t s i t was d e c i d e d t o measure t h e e q u i v a l e n t b l a c k body t e m p e r a t u r e of a wlndow

i n

t h e room where t h e f i r e s t a r t e d . These r a d i a n t t e m p e r a t u r e measurements a r e t h e s u b j e c t of t h i s r e p o r t .

D e s c r i p t i o n of A p p a r ~ t u s and

---

Procedure

A t h e r m o p i l e r a d i o m e t e r d e s i g n e d by Linke and F e u s s n e r and manufactured by P m J o K i p p and Zonen of D e l f t was u s e d

a s

t h e r a d i a t i o n s e n s i n g devico. Tho i n s t r u m e n t was m o d i f i e d by r e p l a c i n g one of t h e 1/2-bil;- d i a m e t e r g l a s s f i l t e r s by a double w a l l e d s c r e e n w i t h a 114-in. d i a m e t e r h o l e a t i t s c e n t r e . With t h i s a p e r t u r e t h e i n s t r ~ ~ r n e n t oould be l o c a t e d up t o 20 f t from a n openlng 2 f t wide a n d s t i l l have t h e opening c o m p l e t e l y f i l l t h e f i e l d of view of t h o i n s t r u m e n t e

The e l e c t r o m o t i v e f o r c e g e n e r a t e d by t h e r a d i o m e t e r thermo- p i l e was r e c o r d e d by a s e l f - b a l a n c i n g p o t e n t i o m e t e r s t r i p - a h a r t r e c o r d e r , The r e c o r d e r had a r a n g e from

-5

t o + 5 m i l l i v o l t s a n d a o h a r t speed of 1 i n . p e r minute, A 5 - m i l l i v o l t b i a s v o l t a g e was p u t i n s e r i e s w i t h t h e p o t e n t i o m e t e r i n p u t s o t h a t t h e e f f e c t i v e range was from 0 t o +10 m i l l i v o l t s .

The r a d i o m e t e r was s e t on a s u r v e y o r ' s t r i p o d a b o u t

5

f t above t h e ground. The t r i p o d was l o c a t e d d i r e c t l y i n f r o n t of and 2 0 f t from a window of t h e room i n which t h e f i r e waa s t a r t e d . To e n s u r e t h a t t h e i n s t r u m e n t was a c c u r a t e l y s i g h t e d on t h e c e n t r e of t h e window t h e f o l l o w i n g p r o c e d u r e was f o l l o w e d :

I* A 250-watt i n f r a - r e d lamp was a t t a c h e d a t t h e c e n t r e of t h e window.

2 e The r a d i o m e t e r o u t p u t was c o n n e c t e d t o a d-c a m p l i f i e r w i t h a n o u t p u t m e t e r whioh s e r v e d a s a galvanometer,

3.

The r a d i o m e t e r was s i g h t e d on t h e lamp u s i n g the peep s i g h t which i s a t t a c h e d t o t h e b a r r e l of t h e i n s t r u m e n t .

4

.

_{The f i n e s i g h t i n g w a s done by a d j u s t i n g} t h e a z i m u t h a n d e l e v a t i o n t o g i v e a maximum o u t p u t from t h e t h e r m o p i l e . W i t h a 250-watt lamp a t 2 0 f t t h e r a d i o m e t e r i s v e r y s e n s i t i v e t o a n g l e , The p r o c e d u r e d u r i n g a b u r n was a s f o l l o w s : 1. The i n s t r u m e n t was s e t up o n t h e t r i p o d a t l e a s t a n hour b e f o r e t h e b u r n s t a r t e d ,

2. The s i g h t i n g was done a s d e s c r i b e d and t h e r a d i o m e t e r o u t p u t was t h e n c o n n e c t e d t o t h e r e c o r d i n g potentiome t e r m The p o l a r i t y of t h e c o n n e c t i o n was checked t o make s u r e t h a t i n c r e a s i n g r a d i a t i o n c a u s e d an o n - s c a l e

3.

With t h e r a d i o m e t e r s h u t t e r c l o s e d t h e b i a s v o l t a g e i n the i n p u t c i r c u i t was a d j u s t e d t o give a r e c o r d e r r e a d i n g of z e r o on the c h a r t ,

4.

The s h u t t e r was r e p l a c e d by t h e

1/4-in.

diameter a p e r t u r e .

5.

A t the o f f i c i a l s t a r t of t h e t e s t t h e r e c o r d e r c h a r t f e e d was s t a r t e d and t h e n t h e r e c o r d e r was l e f t unattended.

6.

The o p e r a t o r went t o t h e r a d i o m e t e r and s t a y e d t h e r e d u r i n g t h e remainder of t h e t e a t . He r e a d and reoorded t h e radiometer temperature a t 1/2-min i n t e r v a l s and

recorded o b s e r v a t i o n s of t h e p r o g r e s s of t h e f i r e , gag., when t h e g l a s s broke, when t h e flames s t a r t e d coming out of t h e window, e t o .

7.

The radiometer was removed when t h e o p e r a t o r thought i t might be damaged by t h e c o l l a p s e of

a

w a l l o r when t h e h e a t was s o i n t e n s e

t h a t he could no l o n g e r s t a y by t h e instrument

A. C a l i b r a t i o n

The radiometer was purchased a s a l a b o r a t o r y s t a n d a r d which could be used t o c a l i b r a t e s o l a r r a d i a t i o n r e c o r d e r s .

A s soon a s i t waa r e c e i v e d i t was checked a g a i n s t t h e S i l v e r Disk Pyrheliometer No.

14

which i s t h e s t a n d a r d used by

the

Meteorological Branch of t h e Department of Transport. The oomparison was made on a c l e a r day u s i n g t h e sun a s a source. The average of many comparisons i n d i c a t e d t h a t t h e f a c t o r f o r t h i s i n s t r u m e n t i s

t

=

instrument temperature O C T h i s i s based on t h e I n t e r n a t i o n a l s c a l e of

1956,

which g i v e s r a d i a t i o n v a l u e s 2 p e r c e n t lower t h a n does t h e

1913

s o a l e . T h i s o a l i b r a t i o n was determined f o r t h e s t a n d a r d a p e r t u r e , n o t t h e s m a l l one. To o b t a i n t h e f a c t o r f o r t h e reduced a p e r t u r e , t h e r a d i o m e t e r was s e t up i n f r o n t of a g a s - f i r e d r a d i a t i o n p a n e l

and' the thermopile o u t p u t was reaorded a s t h e two a p e r t u r e 8 were a l t e r n a t e d . The r a t i o of out u t w i t h small a p e r t u r e t o

f:

o u t p u t w i t h l a r g e a p e r t u r e was 0.2 0. This i s a l s o t h e r a t i o of t h e s o l i d angle of view f o r the two a p e r t u r e s . The s o l i d a n g l e of view f o r t h e s t a n d a r d a p e r t u r e i s given by t h e i n s t r u - ment manufacturer a s W = ?f/125. Thus t h e angle f o r the reduced a p e r t u r e i s 0.260

x

_,

_71'/480.

125

The r a d i a t i o n from a burning b u i l d i n g h a s a peak i n t e n s i t y a t wavelengths between 2 and

2.5

microns, whereas s o l a r r a d i a t i o n

h a s i t s peak i n t e n s i t y a t about 0.5 micron. It was decided t o check t h e radiometer c a l i b r a t i o n f o r long wavelength r a d i a t i o n s l n c e t h e i n s t r u m e n t had only been c a l i b r a t e d w i t h s o l a r r a d i a t i o n . The D i v i s i o n does n o t have a h i g h temperature f u r n a c e which i s s u i t a b l e f o r c a l i b r a t i n g a radiometer i n t h e 2.5-micron range, s o t h a t a blaok body a t 100°C (10-micron wavelength) was used.

The r e s u l t s a r e given i n Appendix A. T h i s t e s t showed t h a t the c a l i b r a t i o n c o n s t a n t f o r t h e i n f r a - r e d r a d i a t i o n i s s l i g h t l y h i g h e r t h a n t h a t f o r the s o l a r spectrum. The f a o t o r a p p r o p r i a t e f o r s o h r r a d i a t i o n was used $or c a l o u l a t i n g the r a d i a n t temperature of t h e burning b u i l d i n g s .

B.

C a l c u l a t i o n of Radiant Temperature from Radiometer Output The normal r a d i a t i o n i n t e n s i t y from a b l a c k body a t T o Kelvin i e

&

-

I n

-

'r

Langley/min S t e r a d i a n

where 4.

=

81.3

x

lom1*

The r a d i a t i o n i n u i d e n t on the thermopile when t h e radiometer f i e l d of view i s completely f i l l e d by' a r a d i a t o r a t

To

Kelvin i s In times t h e s o l i d a n g l e of t h e f i e l d of view,

Thus

i n c i d e n t r a d i a t i o n

=

_{W e ?}

.a

0-A

Langle y/min

and t h e r a d i a t i o n e m i t t e d by t h e radiometer w i t h i n t h i s same s o l i d angle i s

M r . Bernard ~ r u l 6 , Xssaarch Technician w i t h B u i l d i n g S e r v i c e s S e c t i o n was l a r g e l y r e s p o n s i b l e f o r t h e o p e r a t i o n of t h e i n s t r u m e n t a t i o n

i n

t h e f dt'lr:i and provided v a l u e d a s s i s t a n c e .

GROUND FLOOR = PORCH ROOF - J PORCH RAILING ,/ NOTES :

1. ALL WALLS a CEILINGS OF PLASTER

1 INSTRUMENTATION IN BASEMENT WEST CORNER 12

n

lzi CLOSED BEDROOM LEGEND : --4 JHERMOCOUPL ES

A

_b

& RESISTANCE THERMOMETER

0

RADIOMETERS / 0 ' - 2 "x 8 '-3 " El OPEN BEDROOM 8 ' - 0 / / '- 5 " @ THERMOP/L E RADIOMETER \ L7 GAS COLLECTORS " 'b DOWN A SMOKE METERS

b l

0 BEDROOM BEDROOM 10'-2"x 10'-6" 8 ' . 0 ' ' ~ 1 0 ' . ~ ' ' A N E M O M E T E R 0

-

5 10

=

1 F E E T

SASH REMOVED BEFORE F/RE

NOTES:

I . ALL WALLS 8 CEILINGS OF FIBREBOARD EXCEPT

- IN BEDROOMS, WALLS 8 CEILINGS OF PLASTER

- IN KI TCHEN

.

WAINSCOT OF WOO0

2 INSTRUMENTATION WEST CORNER LEGEND - a THERMOCOUPLES RESISTANCE THERMOMETER

0

RADIOMETERS @ THERMOPILE RADIOMETER n GAS COLLECTORS C\ SMOKE METERS

---COVERED WITH

/

PLASTERBOARD GROUND FLOOR . . I5'0"

L

. 3 0 S P _ , : I NOTES :

I ALL WALLS a CEILINGS OF FIBREBOA RD

L-

2 6 ' - 0 " FIRST FLOOR I i l 2. IN BASEMENT WEST CORNER .

f

LEGEND : 4 THERMOCOUPLES

-

-% RESISTANCE THERMOMETER KITCHEN B DINING ROOM 18'-2"x 9'10" 5 2 . LIVING ROOM .

*---

t--4

i

0

RADIOMETERS @ THERMOPILE RADIOMETER 9 ' - l / ' x 18'-2" GAS COLLECTORS 10 O - A F E E T 6 -UP CRIB

FIGURE 3

-

BUILDING No. 3

-

TWO

-

STOREY SOLID BRICK DWELLING

\ COVERED WfTH PLASTERBOARD DINING ROOM 1 4 ' - 1 0 " r 1 5 ' - 5 " SASH

I I

REMOVED GROUND FLOOR NOTES :

I. ALL WALLS 8 CEILINGS OF PLASTER 2 INSTRUMEN TATION IN BASEMENT SOUTH CORNER LEGEND: --o THERMOCOUPL ES

RESISTANCE THERMOhtE TER

0

RADIOMETERS

@ THERMOPILE RAOIOME TER GAS COLL ECTORS

a

SMOKE METERS

F E E T

FIGURE 4

-

BUILDING NO. 4

-

TWO

-

STOREY WOOD FRAME DWELLING WITH CLAPBOARD EXTERIOR AND BRICK INFILLING

! - DOOP L EFT QPEh

\

NOTES :

-- --

J

FIRST FLOOR

I. ALL WALLS 8 CEILINGS OF PRESSED PAPERBOARD 2. INSTRUMEN PA TION IN BASEMENT LEGEND : 4 r m o c o u P L ~ s

-% RESISTANCE PHERMOME TER

0

RADIOMETERS

@ THERMOPILE RADIOME PER

GAS COLLECTORS SMOKE METERS

O I p

F E E T

FIGURE 5 -BUILDING No. 5 - T W O

-

S T O R E Y WOOD F R A M E DWELLING W I T H

> _i

IllU

4

+I

->

" U~ '..

4

STAGE (3'- 6" ABOVE FLOOR)

I'I

-

6

:

NOTE : CEILING a WALLS OF

-a.-.

.

*

. 1- 1 1 1 STEEL POSTS

1

WAINSCOT PLASTER WOOD LEGEND: 4 THERMOCOUPLES RESISTANCE THERMOMETERS ANEMOMETERS

0

RADIOMETERS

@

THERMOPIL E RADIOMETER GROUND FLOOR 0

-

5 10 FEET

FIGURE 6

-

BUILDING NO. 6

-

T W O

-

S T O R E Y SOLID BRICK

GROUND FLOOR

I

N O T E S :

/. ALL WALLS B CEILiNGS

OF PL AS r m

2. _{INS TRUMEN TA TION}

IN BASEMENT SOUTH CORNER LEGEND :

-

THERMOCOUPLES % RESISTANCE THERMOMETER

0

RADIOMETERS

8

THERMOPILE RADIOMETER GAS COLLECTORS SMOKE METERS -F E E T F I R S T F L O O R

NOTE :

-

WALLS OF PLASTER CEILING OF WOOD LEGEND : --o THERMOCOUPLES

& RESISTANCE THERMOMETERS ANEMOMETERS

0

RADIOMETERS THERMOPILE RADIOMETER GROUND FLOOR 0

-

5 10 F E E T

FIGURE 8

-

BUILDING

NO. 8

-

TWO

-

STOREY SOLID

BRICK

B L D G . No. 4 B L D G . No. 7

FIGLIRE 9 RECORDER CHARTS FOR BURNS OF HOUSES WITH INCOMBUSTIBLE LININGS

BLDG. No. 3 815 1 :I. 8 4 8 S 4 6

1 . 1

BJF 8 4 0 8 1 9 800, B e 1 8 6 6 ~r 871 1 B 7 P 1 B O B 1 808 7.e B L D G . No. 2

F I G U R E 10 RECORDER C H A R T S FOR BURNS O F HOUSES W I T H C O M B U S T I B L E L I N I N G S

COMMUNITY HALL AULTSVILLE

FIGURE I!

BLDG. No. 5

RECORDER C H A R T S FOR BURNS No. 5 , 6 ,

8

A P P E N D I X A

CHECK ON R A D I OhEiTER C A L I B R A T I O N A T LONG VJAVELENGTHS

The r a d i o m e t e r was s i g h t e d i n t o a c o n i c a l b l a c k body which was m a i n t a i n e d a t 100°C by condensing steam a t atmospherio p r e s s u r e , A, Data f o r s m a l l a p e r t u r e : _- T

=

373'

K e l v i n C a l c u l a t i o n :

B.

Data f o r s t a n d a r d a p e r t u r e : C a l c u l a t i o n :

125

x

0.092 mv

=

B1.3 x

0.01158 = 12,22 Langle y/min

The good agreement between t h e v a l u e s of K found f o r the s m a l l and t h e s t a n d a r d a p e r t u r e s i s c o n f i r m a t i o n of t h e a c c u r a a y of the s o l i d angle r a t i o .