st. lawrence burns resistance thermometer...

NATIONAL RESERRCH COUNCIL

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

Report No. 155

of t h e

Division of Building Research

OTTAWA

December 195 9

PREFACE

The circumstances tha-t l ed t o t he carrying out of f i r e tes-t;s on e igh t buildings i n t h e p ro jec t known a s t he S t . Lawrence Burns, and the object ives and t h e ways i n which these were achieved a r e f u l l y described i n a general repor t . It cons t i t u t e s t he complete record of t h e planning and execution of t h e experiments, together with a l l general information. The d e t a i l s on each kind of measurement made, including t h e r e s u l t s obtained, a r e contained i n separate companion repor 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 re discussed and f i n a l conclusions drawn i n a summary repor t .

Duplication has been avoided a s f a r a s poss ible , and it w i l l be necessary t o r e f e r t o t he general repor t i n reading any of t h e o ther repor t s including t h i s one f o r any information which i s per t inen t t o more than one of them. A l i s t i n g of a l l r epo r t s on t h e p ro jec t follows t h i s preface.

The pa r t i c ipa t ion of t h e B r i t i s h J o i n t Fi re Research Organization i n t he experiment, t he i n t e r e s t and support of t h e Federal C iv i l Defence a u t h o r i t i e s , t h e ass i s tance of the Ontario Fi re Marshal and h i s s t a f f , and f i n a l l y t he complete co-operation and very considerable ass i s tance extended by the Hydro-Electric Power Commission of Ontario a r e a l l g r a t e f u l l y acknowledged. It is a pleasure a l s o t o be ab le t o record t h e spec ia l contr ibut ion made by members of t h e s t a f f of t h e Fi re Section who worked long hours, o f ten under t r y i n g f i e l d condi- t i o n s and a t g rea t personal inconvenience, t o meet t he many deadlines and t o complete the p ro jec t i n a most s a t i s f ac to ry manner.

The author of t h i s repor t i s M r . J. H. McGuire, now research o f f i c e r with t he Fi re Section of t h i s Division, who a s a member of t he s t a f f of t h e B r i t i s h J o i n t Fire Research Organization planned and supvervised t h e measurements made with the radiometers, anemometers and res i s tance thermometers.

Ottawa December 1959

N. B. Hutcheon Assis tant Director

REPORTS ON THE ST. LA'JJRENCE BURNS

NO. - SUB-TITLX ------

General Report

Smoke and Sound Measurements

Temperature Mea su.rement s

Radiometer Measurements

Vent i la t ion Eate Measurements*

Resistance Thermometer Measurements

Radiant Temperature of Openings

Gas Analysis

Summary Report

G. iV. Shorter

G. Williams-Leir

G. Williams-Leir

J. B. McGuire

J. H. McGuire

J. H. NcGuire

D. G. . Stephenson

J. R. J u t r a s

G. W . Shor ter and J. H. McGuire

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 burning experiments were c a r r i e d out 8-t Aul tsv i l l . e , Ontar io, by t h e F i re Sect ion of t h e Divis ion of Bixildiny Research, Nat ional Research Council. The general, d - e t a i l s , which involved t h e burni:ng of s i x dwellings and two l a r g e r bu i ld ings , a r e described i n t h e first of a s e r i e s of repor-t;s on t h e S t . Lawrence Burns (1).

This r e p o r t i s concerned with res is ta .nce 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 hea t content of t h e gases i n - a burning enclosure. Measurement of t h e r e s i s t a n c e of a wire g ives i t s mean tempera-ture, t o a c lose approximation, and if t h e wire i s t h i n i s a measure of t h e mean temperature of th.e gases surrounding t h e l e n g t h of t h e wire, The h e a t content of t h e gases can then be estimated. by p o s t u l a t i n g t h e form of t h e temperature d i s t r i b u - t i o n a long t h e l eng th of t h e wire.

The sens ing element of t h e r e s i s t a n c e thermometer was requilled t o have a length of about 6 f t f o r t h e measurements i n t h e houses and between 20 and 30 ft f o r t h e measurements i n t h e l a r g e r build.int;s. A t ime cons tant of l e s s than a minute was a l s o e s s e n t i a l . Copper wire meets these r equ i re - ments, and a r e s i s t a n c e measuring br idge (Fig. 9) was constructed f o r an e1.emen-b r e s i s t a n c e of 3 ohms a t ambient temperature, Such a va lue of r e s i s t a n c e i s given by approxi- mately 6 f t of 40 swg copper wire 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 br idge i s shown i n Fig. 10. The \:t%eatstone br idge i s dupl ica ted t o a l low t h e use of two r e s i s t a n c e wire elements, if necessary, and c o n t r o l s and mil l iarneters a r e incorporated t o a l l o n s t andard iza t ion 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 balance 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 per cent- d i f f e r e n t from 3 ohms i s u-scd. Cal ibra t ion of t h e hl- idge unit . ; i s given in Pig. 11. 3rirl .g~. ou-l-pu-1;~ were con- ~r:c'i;~:c3. -1;o servo-potentiome-tl-ic:. pen rt?corcic?rs,

LO\CATIObT OF RESISTANCE ELI3hTEhTS

I n each o f t he houses 40 swg res i s tance wire was mounter1 near t h e s t a i r ca se a s indicated i n Pigs. 1 t o 5 ,7 ; it s t re tched from a point 1 ft above t h e f l o o r t o a point app ro~ ima te ly 1 f t 6 in . belcw the ground f l o o r c e i l i n g leve l . I n t h e l a r g e r buildings two elements of 34 swg copper wire were instal l .ed a t the s i t e s shown i n Pigs. 6 and 8. The length of t he wire was approximately 21 f t with i t s lower end a t ground f l o o r level-.

RESULTS

Results a r e given i n Figs. 12 t o 17 and have been corrected f o r t he e f fec t introduced by connecting-lead res i s tance .

No d i r e c t s ignif icance may be given t o t h e r e s u l t s f o r t h e second res i s tance element used i n the l a r g e r bui ld ings; af-1;er t h e experiments had been completed it was found t h a t the recorder which was fed from bridge A was f au l ty . It w i l l be not iced, however, t h a t t he time waveform of t h e re levant out- puts i s s imi l a r i n t he case of each o f t h e l a rge buildings. It is l i k e l y t h a t t he e r r o r i n t h e reading i s a constant fac - t o r . Assuming t h i s t o be t r u e , it can be s a id t h a t the gases i n t he buildings were s t r a t i f i e d r i g h t up t o t he time of f l a sh - over, when flames enveloped the res i s tance wires and they were destroyed.

HE4T CONTLZNT OF THE GASES

If it i s des i red , from t h e r e s u 1 . t ~ given, t o determine the heat content of t h e gases a t any time, then it must be assurned t h a t temperature i s a funct ion of height only and t h a t the form of t he function i s knovm. The requirement t h a t t he function be known a r i s e s from t h e f a c t t h a t densi ty i s a func- t i o n of temperature and hence the expression f o r t h e hea t content is:

where A = f l o o r a rea of bui ld ing

H = height

Po = densi ty a t ambient temperature To

s = s p e c i f i c heat

and 8 = temperature r i s e above ambient temperature To

The ca l ib ra t i on of the res i s tance bridge gives a measure of

H "h

which d i f f e r s i n form from the i n t e g r a l i n t he previous expression. Some assumption must theref ore be made about the va r i a t i on of temperature with height . The heat con- t e n t of t h e gases i n the school, up t o a height of 2 1 f t ( the height of the res i s tance wire) and f o r a time of 1 4 minutes a f t e r i gn i t i on , has been calcula ted f o r four d i f f e r e n t assumed temperature-height funct ions; 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 he f o u r assumed distribu-bions i s an ex- treme one which requires a c e i l i n g temperature higher than 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 there fore rea- sonable t o rosurne 2.5 * lo7 a s t h e bes t est imate of t he heat ccnta2n-L a t 1 4 minu.tcs.

1. Shorter , G.Mr. St. Lawrence Burns - General Report. N.R.C. , DBR In t e rna l Report No. 150, November 1959.

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

NOTES :

I. ALL WALLS 6) CEILINGS OF PLASTFR

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

ANEMOMETER

0 5 10

r : . 1 F E E T

FIGURE I - BUILDING No. I - TWO - STOREY SOLID BRICK DWELLING

SASH

REMOVED

BEFORE FIRE

10'-8'; 10'-5"

CLOSED BEDROOM ,, 12'- OWr 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

FIGURE 2 - BUILDING NO. 2 - TWO - STOREY SOLID BRICK DWELLING

--- 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

26'-OU +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

1 COVERED WITH PLASTERBOARD

OINING ROOM

LC WER ------- 14'-10 "r 15'- 5 " SASH

REMOVED

LIVING ROOM -- / / ' - 2 ' ; 14 ' -9"

GROUND FLOOR 1

LIVING ROOM // ' -2"# 14 ' -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

"U F E E T

FIGURE 4 - BUILDING NO. 4 - TWO - STOREY WOOD FRAME DWELLING WITH

CLAPBOARD EXTERIOR AND BRICK INFILLING

\ 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

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.

FEET

F IGURE 6 - BUILDING No. 6 - T W O - STOREY SOLID BRICK

FRATERNITY HALL

r- L EFT OPEN ,

GROUND FLOOR

14

-- DINING ROOM

11'-6" 1 2 2 ' - 0 "

LIVING ROOM

N'-6" x 2 2 ' - 0 " 2 30 '

FIRST FLOOR

7 I 6 4

NOTES:

I . ALL WALLS B CEILINGS OF PLASTER

--

2. INS TRUAI.CN TA TI ON IN BASEMENT SOUTH CORNER

t i 1 -

LEGEND :

THERMOCOUPLES

-% RESISTANCE THERMOMETER

0 R AOJOME TERS

@ THERMOPILE RAOIOMETER

GAS COLLECTORS

SMOKE METERS

"U F E E T

FIGURE 7 - BUILDING NO. 7 - TWO - STOREY SOLID BRICK DWELLING

Nor€ : WALLS OF PLASTER CEILING OF WOOD

LEGEND :

--o THERMOCOUPLES

% RESISTANCE THERMOMETERS

ANEMOMETERS

0 RADIOMETERS

@ THERMOPILE RADIOMETER

GROUND FLOOR

0 5 10 - FEET

F IGURE 8 - B,UILDING NO. 8 - T W O - STOREY SOLID BRICK

SCHOOL WITH ONE - STOREY EXTENSION AT REAR

FIGUEZE 9 MEASURING BRIDGE

BU

RN

N

O.

I B

UR

N

NO

. 2

6

8

10

TlM

E

(MIN

.)

0

2

4

TlM

E

(MIN

.)

FIG

UR

E

12

TE

MP

ER

AT

UR

E-T

IME

C

UR

VE

S

BU

RN

N

O. 8

SC

HO

OL

6

8 10

T

IME

(M

IN.)

FIG

UR

E

17

TE

MP

ER

AT

UR

E-T

IME

C

UR

VE

S