St. Lawrence Burns: resistance thermometer measurements

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NATIONAL RESERRCH C O U N C I L CAXADA D I V I S I O N OF B U I L D I N G RESEARCH S T . LAWRENCE BURNS R E S I S T A N C E THERMOMETER MFASURmvIFNTS J . H . McGuire R e p o r t No.

1 5 5

o f t h e Division o f Building R e s e a r c h OTTAWA December 195

9

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PREFACE

The circumstances tha-t l e d t o t h e c a r r y i n g out of f i r e tes-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 known a s t h e

S t . Lawrence Burns, and t h e o b j e c t i v e s and t h e ways i n which t h e s e were achieved 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 record of t h e planning and execution of t h e experiments, t o g e t h e r w i t h a l l g e n e r a l information. 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 contained 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 conclusions drawn i n a summary r e p o r t .

Duplication has been avoided a s f a r a s p o s s i b l e , and

it 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 information 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 of a l l r e p o r t s on t h e p r o j e c t follows t h i s preface.

The 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 support 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 Ontario 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 co-operation and very considerable a s s i s t a n c e extended by t h e Hydro-Electric Power Commission of Ontario 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 record 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 long h o u r s , o f t e n under t r y i n g f i e l d condi- t i o n s and a t g r e a t personal 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 M r . J. H. McGuire, now 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 Section of t h i s D i v i s i o n , who a s a member of t h e s t a f f of t h e B r i t i s h J o i n t F i r e Research Organization planned and supvervised t h e measurements made with t h e r a d i o m e t e r s , anemometers and r e s i s t a n c e thermometers.

Ottawa

December 1959

N. B. Hutcheon A s s i s t a n t D i r e c t o r

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REPORTS ON

THE

ST. LA'JJRENCE BURNS

NO.

-

_---SUB-TITLX

General Report

Smoke and Sound Measurements Temperature Mea su.rement s Radiometer Measurements

V e n t i l a t i o n Eate Measurements* R e s i s t a n c e Thermometer

Measurements

Radiant Temperature of Openings Gas A n a l y s i s Summary Report G. iV. S h o r t e r G. W i l l i a m s - L e i r G. W i l l i a m s - L e i r J.

B.

McGuire J. H. McGuire J. H. NcGuire D. G . . Stephenson J . R. J u t r a s G. W . S h o r t e r and J . H. McGuire

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ST. LIITREITCE BUI;"NS

J . H . McGilire

Ear1.y i n 1958 a number of c o n t r o l l e d b u r n i n g

experiments were c a r r i e d o u t 8-t A u l t s v i l l . e , O n t a r i o , by t h e F i r e S e c t i o n of t h e D i v i s i o n of Bixildiny Research, N a t i o n a l Research Council. The general, d - e t a i l s

,

which i n v o l v e d t h e burni:ng of s i x d w e l l i n g s and two l a r g e r b u i l d i n g s , a r e d e s c r i b e d i n t h e f i r s t of a s e r i e s of repor-t;s on t h e S t . Lawrence

Burns

(1).

T h i s r e p o r t i s concerned w i t h r e s i s t a . n c e wire thermometer measu.rements maCLe by t h e B r i t i s h J o i n t F i r e Research Or,gmization t o provide i n f orma-tion on t h e grovrth of t h e h e a t c o n t e n t of t h e g a s e s i n - a b u r n i n g e n c l o s u r e . Measurement of t h e r e s i s t a n c e of a wire g i v e s i t s mean tempera-ture, t o a c l o s e approximation, and if t h e w i r e i s t h i n i s a measure of t h e mean t e m p e r a t u r e of th.e g a s e s s u r r o u n d i n g t h e l e n g t h of t h e w i r e , The h e a t c o n t e n t of t h e g a s e s can t h e n be estimated. by p o s t u l a t i n g t h e form of t h e t e m p e r a t u r e d i s t r i b u - t i o n a l o n g t h e l e n g t h of t h e wire.

The s e n s i n g element of t h e r e s i s t a n c e thermometer was requilled t o have a l e n g t h of a b o u t 6

f t

f o r t h e measurements i n t h e houses and between 20 and 30

f t

f o r t h e measurements i n t h e l a r g e r build.int;s. A t i m e c o n s t a n t of l e s s t h a n a minute was a l s o e s s e n t i a l . Copper w i r e meets t h e s e r e q u i r e - ments, and a r e s i s t a n c e measuring b r i d g e ( F i g .

9)

was

c o n s t r u c t e d f o r a n e1.emen-b r e s i s t a n c e of 3 ohms a t ambient t e m p e r a t u r e , Such a v a l u e of r e s i s t a n c e i s g i v e n by a p p r o x i - mately 6 f t of 40 swg copper w i r e o r 25 f t of 34 swg copper wire.

The c i r c u i t of t h e r e s i s t a n c e b r i d g e i s shown i n Fig. 10. The \:t%eatstone b r i d g e i s d u p l i c a t e d t o a l l o w t h e use of two r e s i s t a n c e wire e l e m e n t s , if n e c e s s a r y , and c o n t r o l s and m i l l i a r n e t e r s a r e i n c o r p o r a t e d t o a l l o n s t a n d a r d i z a t i o n of t h e p o t e n t i a l d i f f e r e n c e s a c r o s s t h e bri-dge and t o b a l a n c e it a t a r ~ h i e n t t<.n.)pe~:a-tu~.-e vdlen an element w i t h a r e s i s t a n c e a few p e r cent- d i f f e r e n t from 3 ohms i s u-scd. C a l i b r a t i o n of t h e h l - i d g e u n i t . ; i s g i v e n in Pig. 11. 3 r i r l . g ~ . ou-l-pu-1;~ were con-

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LO\CATIObT

OF RESISTANCE

ELI3hTEhTS

I n each o f t h e houses

40

swg r e s i s t a n c e wire was mounter1 n e a r t h e s t a i r c a s e a s i n d i c a t e d i n Pigs. 1 t o 5 , 7 ;

it s t r e t c h e d from a p o i n t 1 ft above t h e f l o o r t o a p o i n t

a p p r o ~ i m a t e l y 1 f t 6 i n . belcw t h e ground f l o o r c e i l i n g l e v e l . I n t h e l a r g e r b u i l d i n g s two elements of

34

swg copper wire

were i n s t a l l . e d a t t h e s i t e s shown i n P i g s . 6 _{and 8.} _{The l e n g t h}

of t h e wire was approximately 21 f t w i t h i t s lower end a t ground f l o o r level-.

RESULTS

R e s u l t s a r e given i n Figs. 1 2 t o 1 7 and have been c o r r e c t e d f o r t h e e f f e c t introduced by connecting-lead

r e s i s t a n c e .

No d i r e c t s i g n i f i c a n c e may be given t o t h e r e s u l t s f o r t h e second r e s i s t a n c e element used i n t h e l a r g e r b u i l d i n g s ;

af-1;er t h e experiments had been completed it was found t h a t t h e r e c o r d e r which was f e d from b r i d g e A was f a u l t y . It w i l l be n o t i c e d , however, t h a t t h e time waveform of t h e r e l e v a n t out- p u t s i s s i m i l a r i n t h e c a s e of each o f t h e l a r g e b u i l d i n g s . It i s l i k e l y t h a t t h e e r r o r i n t h e r e a d i n g i s a c o n s t a n t f a c - t o r . Assuming t h i s t o be t r u e , it can be s a i d t h a t t h e gases i n t h e b u i l d i n g s were s t r a t i f i e d r i g h t up t o t h e time of f l a s h - over, when flames enveloped t h e r e s i s t a n c e wires and t h e y were destroyed.

HE4T CONTLZNT OF THE GASES

If it i s d e s i r e d , from t h e r e s u 1 . t ~ given, t o determine t h e h e a t c o n t e n t of t h e gases a t any t i m e , t h e n it must be

assurned t h a t temperature i s a f u n c t i o n of h e i g h t only and t h a t t h e form of t h e f u n c t i o n i s knovm. The requirement t h a t t h e f u n c t i o n be known a r i s e s from t h e f a c t t h a t d e n s i t y i s a func- t i o n of temperature and hence t h e e x p r e s s i o n f o r t h e h e a t

c o n t e n t i s :

where A = f l o o r a r e a of b u i l d i n g

H

= h e i g h t

Po = d e n s i t y a t ambient temperature To s = s p e c i f i c h e a t

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The c a l i b r a t i o n of t h e r e s i s t a n c e b r i d g e g i v e s a measure of

H

"h

which d i f f e r s i n form from t h e i n t e g r a l i n t h e previous expression. Some assumption must t h e r e f o r e be made about t h e v a r i a t i o n of temperature with h e i g h t . The h e a t con- t e n t of t h e gases i n t h e school, up t o a h e i g h t of 2 1 f t ( t h e h e i g h t of t h e r e s i s t a n c e w i r e ) and f o r a time of

1 4

minutes a f t e r i g n i t i o n , has been c a l c u l a t e d f o r f o u r d i f f e r e n t assumed temperature-height f u n c t i o n s ; t h e r e s u l t s a r e given i n Table I.

The l a s t of t h e f o u r assumed d i s t r i b u - b i o n s i s a n ex- treme one which r e q u i r e s a c e i l i n g temperature h i g h e r t h a n wou-l? be a t t a i n e d i n f i r e s of t h i s kind. It i s t h e r e f o r e r e a - sonable t o rosurne 2.5

*

lo7

a s t h e b e s t e s t i m a t e of t h e h e a t ccnta2n-L a t 1 4 minu.tcs.

1. S h o r t e r , G.Mr. St. Lawrence

Burns

-

General Report.

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TABLE

I

HEAT

CONTENT OF GASES

IN

SCHOOL AFTER 14 NINUTES

Heat content

r e a h

o 2.84

x

107 calories Assumed temperature- height function 2.98

x

lo7 calories 1..99

x

107 calories 1.16

x

107 calories

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NOTES :

I. ALL WALLS 6) CEILINGS OF P L A S T F R

I 2 0 ' - 3 "

J

FIRST FLOOR INSTRUMENTATION IN BASEMENT WEST CORNER LEGEND : 4 THERMOCOUPL ES

-% RESISTANCE THERMOME TER

0

RADIOMETERS

@ THERMOPILE RA DlOME TER

GAS COLLECTORS SMOKE METERS A N E M O M E T E R 0 5 10 r : . 1 F E E T

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SASH REMOVED BEFORE FIRE 10'-8'; 10'-5" CLOSED BEDROOM ,, 12'- O W r 8 ' - J "

.--

FIRST FLOOR - -NOTES.

I . ALL WALLS 8 CEILINGS OF FlBREBO4RD EXCEPT

- IN BEDROOMS, WALLS B CFIL INGS OF PLASTER

- IN KITCHEN, WAINSCOT OF WOOD INS TRUMENTA TION IN BASEMENT WEST CORNER L EGEND THERMOCOUPL € 5 % RESISTANCE THERMOMETER

0

RADIOME TERS @ THERMOPILE RADIOMETER

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--- COVERED WITH

[

PLASTERBOARD KITCHEN i3 DINING ROOM 18'-ZNr 9'- 10" LIVING ROOM 9'- 1l"x 18'-2" WOOD

f

CRIB I - - -GROUND FLOOR FIRST FLOOR T NOTES;

I. ALL WALLS a CEILINGS OF FIBREBOARD 2. INSTRUMEN TATION IN BASEMENT WEST CORNER 2 6 ' - O U

+I

u

OPEN BEDROOM

).

10'-1 " x 7'- 9" _IOr LEGEND : 4 THERMOCOUPLES -% RESISTANCE THERMOMETER

0

RADIOMETERS THERMOPILE RADIOMETER

"

o--- -& DN GAS COLLECTORS BEDROOM

a

SMOKE METERS I

1

- 9'-/IN.? 18'2" -% O U FEET

FIGURE 3

-

BUILDING No. 3

-

TWO

-

STOREY SOLID BRICK DWELLING

I I CLOSED BEDROOM 10'- I".? 9'-11" 2

A_-

-

A 1

9

n

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1 COVERED WITH PLASTERBOARD OINING ROOM LC WER

---

14'-10 " r 1 5 ' - 5 " SASH REMOVED LIVING ROOM - - / / ' - 2 ' ; 1 4 ' - 9 " GROUND FLOOR

1

LIVING ROOM / / ' - 2 " # 1 4 ' - 9 " NOTES :

I. ALL WALLS 8 CEILINGS OF PLASTER 2. INSTRUMEN TA NON / N B4SEMENT SOUTH CORNER LEGEND ., 4 THERMOCOUPLES

fia RESISTANCE THERMOMETER

I

0

RADIOMETERS @ THERMOPILE RADIOMETER

I

GAS COLLECTORS

I

SMOKE METERS

"

_{F E E T}

U

FIGURE 4

-

BUILDING NO. 4

-

T W O

-

STOREY WOOD FRAME DWELLING WITH CLAPBOARD EXTERIOR AND BRICK INFILLING

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\ OOUR r.EFT OPEN KITCHEN /9'-0"# 8 ' - 6 " L/VING ROOM 19'- 0 " x 12'- 2 " b GROUND FLOOR OPEN BEDROOM I NOTES :

I . ALL WALLS 6 CEILINGS OF

PRESSED PAPERBOARD INSTRUMEN TA TION IN BASEMENT LEGEND .' 4 THERMOCOUPLES RESISTANCE THERMOMETER

0

RADIOMETERS @ THERMOPILE RADIOMETER GAS COLLECTORS

"

U

F E E T FIRST FLOOR

FIGURE 5 -BUILDING NO. 5 - TWO

-

STOREY WOOD FRAME DWELLING WITH CLAPBOARD EXTERIOR

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NOTE .'

CEILING 8 WAfNSCOT OF WOOD WALLS OF PLASTER LEGEND -4 THERMOCOUPLES RESISTANCE THERMOMETERS ANEMOMETERS

0

RADIOMETERS

@

THERMOPILE RADIOMETER GROUND FLOOR 0 5 10 LLLLIJ. F E E T

F I G U R E 6

-

BUILDING No. 6

-

T W O

-

S T O R E Y SOLID B R I C K

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r- L EFT OPEN , GROUND FLOOR 14 - - DINING ROOM 11'-6" 1 2 2 ' - 0 " LIVING ROOM N ' - 6 " x 2 2 ' - 0 " 2 3 0 ' FIRST FLOOR