Contribution of protected plastic foams to fire growth

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Contribution of protected plastic foams to fire growth

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NATIONAL RESEARCH COUNCIL OF CANADA

DIVISION OF BUILDING RESEARCH

CONTRIBUTION OF PROTECTED PLASTIC

FOAMS TO FIRE GROWTH

T.T. Lie

Fire Study No.

37

of the

Division of Building Research

Ottawa

September 1975

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CONTRIBUTION OF PROTECTED PLASTIC FOAMS TO FIRE GROWTH by T.T. Lie

ABSTRACT

A furnace t e s t method f o r e v a l u a t i n g t h e a b i l i t y o f p r o t e c t i v e m a t e r i a l s t o prevent e x c e s s i v e c o n t r i b u t i o n of p l a s t i c foams t o f i r e growth i s d e s c r i b e d . Furnace t e s t r e s u l t s were compared with t h o s e obtained during t e s t s i n which t h e growth of a f i r e i n a c o r n e r o f a room was simulated. The time of f a i l u r e , a s determined by t h e furnace t e s t s , was found t o be a c o n s e r v a t i v e e s t i m a t e of t h e time b e f o r e p r o t e c t e d p l a s t i c foams began t o

c o n t r i b u t e s i g n i f i c a n t l y t o f i r e growth.

L'ALIMENTATION DES INCENDIES PAR LES MOUSSES PLASTIQUES P R O T ~ G ~ E S par T.T. Lie

L'auteur d6crit une mEthode d'essai au four qui sert 5 Evaluer 1'habiletE de certains matgriaux protecteurs 2 empzcher l'alimentation excessive des incendies par les mousses plastiques. Les rEsultats des essais au four sont comparEs 2 ceux d'essais simulant la croissance d'un incendie dans le coin d'une pike. Le moment de rupture d6terminE d'aprss les essais au four se r6vSle une Evaluation prudente du temps dont disposent les occupants pour Evacuer les lieux de l'incendie avant que les mousses plastiques ne commencent 5 alimenter le feu de fason marqu6e.

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CONTRIBUTION OF PROTECTED PLASTIC FOAMS TO FIRE GROWTH

by T.T. Lie

S e v e r a l b u i l d i n g codes i n North America, i n c l u d i n g t h e National Building Code of ~ a n a d a , ~ regard a m a t e r i a l with a flame- spread r a t i n g of 25 o r l e s s a s a s c e r t a i n e d by ASTM ~ 8 4 , ~ a s a low- f i r e - h a z a r d m a t e r i a l . Recent t e s t s c a r r i e d out on urethane foam, however, suggest t h a t foams may a c c e l e r a t e t h e growth of f i r e much

f a s t e r than expected.

Concern about t h i s p o s s i b i l i t y and t h e occurrence of a number of l a r g e - l o s s f i r e s involving p l a s t i c foam has l e d t o more s t r i n g e n t requirements regarding t h e use of foams. One of t h e s e requirements i s t h a t p l a s t i c foams should be p r o t e c t e d by a thermal b a r r i e r capable of preventing excessive t r a n s f e r of h e a t from h e a t s o u r c e t o p l a s t i c foam during a s p e c i f i e d time.

In t h i s paper a method i s discussed f o r a s s e s s i n g t h e behaviour of p r o t e c t e d foams during t h e growth period of a f i r e , i . e . , t h e period between t h e s t a r t of a f i r e and t h e occurrence of f l a s h o v e r .

GROWTH PERIOD OF FIRE

Normally a s e v e r e f i r e i n a room s t a r t s with a small f i r e caused by i g n i t i o n of a m a t e r i a l by a h e a t s o u r c e , f o r example, t h e flame o f a match o r t h a t of a burning waste paper b a s k e t . Depending on v a r i o u s f a c t o r s , such a s t h e n a t u r e of t h e m a t e r i a l t h a t i s exposed t o t h e i g n i t i o n source o r t h e s i z e of t h e i g n i t i o n source, t h e f i r e may go out o r grow t o a f u l l y developed f i r e . Usually t h e f u l l y developed s t a g e o f a f i r e i s preceded by a phenomenon known a s f l a s h o v e r , which i s c h a r a c t e r i z e d by an almost i n s t a n t a n e o u s i g n i t i o n of m a t e r i a l s i n a l l p a r t s of t h e room.

I n t h e growth p e r i o d , i . e . , t h e p e r i o d b e f o r e occurrence o f f l a s h o v e r (Fig. I ) , t h e temperatures i n t h e room a r e r e l a t i v e l y low even c l o s e t o t h e burning m a t e r i a l and evacuation from t h e f i r e a r e a p r e s e n t s no problems. During t h e f l a s h o v e r , however, t h e temperature r i s e s very s h a r p l y t o such a l e v e l t h a t s u r v i v a l of t h e f i r e by

persons s t i l l i n t h e room a t t h a t s t a g e becomes u n l i k e l y . Thus t h e time i n t e r v a l between t h e s t a r t of a f i r e and t h e occurrence of f l a s h o v e r determines t h e time t h a t i s a v a i l a b l e f o r s a f e evacuation o f t h e f i r e a r e a .

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TEST CONDITIONS

Tests were carried out on various protected foams to assess

the time protected foams need to be exposed to the heat of an ignition

source before contributing to the fire growth. In practice, ignition

sources vary in size as well as in temperature. Only one heat source,

regarded as more severe than the ignition sources normally met with in

practice, was used in the tests for simplicity. The severity of the

heat source was equivalent to a heat flux to an exposed area of

29 1/4 in. by 31 in. of test specimen from a furnace (Fig. 2) with an

emissivity close to that of a black body in which temperatures are

produced according to the ASTM ~1

19-734 standard temperature-time

curve (Fig. 3)

.

In practice, there is often an air space between the protec-

tion and foam. The worst condition, however, with regard to the

temperature rise on the foam surface is if there is no air space

between foam and protection. Therefore, this condition was chosen as

the test condition.

TEST SPECIMENS

A test specimen consisted of a layer of foam plastic covered

on one side by the protecting material to be examined, and on the

other side by 3/8-in. asbestos board, which served as a back support

to the foam and helped keep it flat (Fig.

2).

As the protected material, two commonly used foam plastics

were chosen, polystyrene and polyurethane foam. As protecting

material, gypsum wallboard, plywood and magnesium oxychloride in

various thicknesses were examined. Each test specimen was 32 in. high

and 34 in. wide. Prior to testing they were conditioned in an

atmosphere of 70'~ and 50 per cent relative humidity. The particulars

of the test specimens were as follows:

Protected Foams

Density: 0.9 lb/cu ft

Thickness: 1 in.

Flame-

spread rating (ASTM ~84-70)

:

greater than 500

2.

Polyurethane foam A

Density: 2.8 lb/cu ft

Thickness: 1 in.

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3. Polyurethane foam

B

Density: 2.5 lb/cu ft

Thickness: approximately 1 1/2 in.

Flame-spread rating (ASTM ~84-70)

:

greater than 500

4. Polyurethane foam

C

Density: 2.4 lb/cu ft

Thickness: approximately 1 1/2 in.

Flame-spread rating (ASTM ~84-70)

: 65

Protectine Materials

1. Gypsum board A

Type: regular

Thickness: 3/8 in.

2. Gypsum board

B

Type: regular

Thickness: 1/2 in.

3. Plywood

Type: fir

Thickness: 112 in.

4. Magnesium oxychloride A

Density: 62 lb/cu ft

Thickness: approximately 3/8 in. (irregular thickness)

5. Magnesium oxychloride

B

Density: 62 lb/cu ft

Thickness: approximately 1/2 in. (irregular thickness)

TEST APPARATUS

The test apparatus is shown in Figure 2; the numbers

in parenthesis identify elements in the test set-up. During the test,

the specimen (1) was attached vertically against a test furnace with

the aid of steel bars (2) so that an area of the protecting material,

29 1/4 in. high and 31 in. wide, could be exposed to the heat of the

furnace.

The test furnace (3) was built mainly from insulating fire

brick and was heated electrically with the aid of silicon carbide

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h e a t i n g elements ( 4 ) , placed behind an inconel p l a t e (5). The furnace chamber (6) was 29 1/4 i n . high, 31 i n . wide and 8 1/4 i n . deep.

Observations o f t h e exposed s u r f a c e of t h e specimen could be made through p o r t s (7) c u t i n t h e s i d e wall of t h e furnace. (A more detailed d e s c r i p t i o n of t h e t e s t furnace i s given i n r e f e r e n c e 5.)

TEST PROCEDURE

The t e s t s were c a r r i e d o u t by exposing a t e s t specimen t o t h e h e a t of a t e s t furnace, which was c o n t r o l l e d i n such a way t h a t t h e average temperature i n t h e f u r n a c e chamber c l o s e l y followed t h e standard temperature-versus-time curve (Fig. 3) p r e s c r i b e d by

ASTM E119-73.4 The temperature o f t h e furnace was measured a t f i v e l o c a t i o n s by t h e r m o c ~ u ~ l e s ; ~ t h e average of t h e temperatures a t t h e s e p l a c e s was regarded a s t h e average f u r n a c e temperature.

During t h e t e s t , temperatures were a l s o measured a t t h e i n t e r f a c e between foam and p r o t e c t i n g m a t e r i a l s a t f i v e l o c a t i o n s , one i n t h e c e n t r e and t h e o t h e r f o u r i n t h e c e n t r e of each q u a r t e r s e c t i o n of t h e i n t e r f a c e . The i n i t i a l temperature o f t h e specimens was approximately 7S°F.

The p r o g r e s s o f t h e t e s t was observed by means of t h e p o r t s i n t h e furnace w a l l . The t e s t s were terminated a f t e r measuring an average temperature r i s e a t t h e i n t e r f a c e of approximately 400 F deg.

Several r e p e a t t e s t s were c a r r i e d o u t t o examine t h e v a r i a b i l i t y of t e s t r e s u l t s

.

FAILURE CRITERION

ASTM ~ 1 1 9 - 7 3 4 t e s t method, f o r e v a l u a t i n g t h e a b i l i t y of p r o t e c t i o n t o prevent i g n i t i o n of combustible m a t e r i a l s , r e g a r d s a

temperature r i s e of 250 F deg a t t h e i n t e r f a c e between p r o t e c t e d and p r o t e c t i n g m a t e r i a l a s t h e p o i n t of f a i l u r e . I n t h e t e s t s on

p r o t e c t e d foams t h i s temperature was a l s o chosen a s f a i l u r e temperature.

Thermogravimetric a n a l y s e s 6 showed t h a t a t a temperature of 3 2 5 ' ~ ~ which i s e q u i v a l e n t t o a temperature r i s e o f 250 F deg from an i n i t i a l temperature of 7S°F, t h e weight l o s s of commonly used p l a s t i c foams i s s t i l l very small (Table I ) . I t can be shown t h a t , a t t h i s s t a g e , t h e h e a t t h a t can be r e l e a s e d i n a room by t h e foam i s of t h e o r d e r o f 800 Btu (based on an exposed a r e a o f 10 sq f t , a foam t h i c k n e s s of 0.5 i n . a t 32S°F, a d e n s i t y o f t h e foam of 2 l b / c u f t , a h e a t o f combustion o f 10,000 Btu/lb, and an average weight l o s s of 10 p e r c e n t o f t h e m a t e r i a l ) . This h e a t i s l e s s t h a n t h e h e a t c o n t e n t of one square f o o t o f an average c a r p e t and i f r e l e a s e d i n a room w i l l obviously n o t be a t h r e a t t o p e r s o n s , from t h e p o i n t of view of t h e i r a b i l i t y t o evacuate a room. Therefore a temperature r i s e of 250 F deg a t t h e i n t e r f a c e between foam and p r o t e c t i o n may be regarded a s a c o n s e r v a t i v e f a i l u r e c r i t e r i o n f o r p r o t e c t e d p l a s t i c foams.

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Table

I

Weight loss of various plastic foams at 32S°F, percentage of original weight

FURNACE TEST RESULTS

FOAM MATERIAL I

Test results for various protected plastic foams are shown in Table 11. This table lists the times required to reach a

temperature rise of 250 F deg at the interface between protection and foam.

Table I1 Time, in minutes, to reach average temperature rise of 250 F deg at interface plastic foam and protection

WEIGHT LOSS,

0 ,

*

F.S.R. = flame-spread rating according to ASTM E84-70

DENSITY, lb/cu ft Polyurethane 1 Polyurethane 2 Polyurethane 3 Polyurethane 4 Polystyrene PVC Urea formaldehyde I socyanurat e Phenolic \

PLASTIC

FOAM POLYURETHANE

FLAME-SPREAD R-tTINC;,

ASTM

~84-702

-

2.6 2.2 2 2.6 1 5.6 0.75 2.5 2.5 6 6.5 4 4.5 1 16 6.5

7

9

B 25 4 0 >SO0 600 2 5

- -

-

3 0 10 C

1 I

(F.S.R. = 65)' -

-

!

-

I 11 I (F.S.R.>500)

--

-

- - - - POLYSTYRENE A

PROTECT

ION

(F.S.R.* 2500) (F.S.R.>SOO)

Gypsum wallboard A (3/8-in.) Gypsum wallboard

B

(1/2-in.) Fir plywood (112-in.) Magnesium oxychloride A (Approx. 3/8-in.) 2 7

- -

,

! I Magnesium oxychloride

B

(Approx. 1/2-in.)

12.5;

10.5;

12.5; 9.5 16; 15; 16.5 11.5; 10.5; 12

- -

14;

9; 10.5 14.5; 15; 14.5 10.5; 10; 11

- -

-

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I n a l l t e s t s with gypsum board and plywood p r o t e c t i o n , flames were observed i n t h e furnace chamber about 4 minutes a f t e r t h e s t a r t of t h e t e s t . In t h e c a s e o f gypsum board, t h e flaming caused by burning of t h e paper s u r f a c e on t h e board stopped a f t e r about one minute. Flaming s t a r t e d again a f t e r cracks formed i n t h e gypsum

board a t a l a t e r s t a g e o f t h e t e s t . In t h e c a s e o f plywood p r o t e c t i o n , t h e flaming continued u n t i l t h e end o f t h e t e s t .

During t h e t e s t with magnesium oxychloride p r o t e c t i o n , no flames were observed u n t i l c l o s e t o t h e end o f t h e t e s t when cracks formed i n t h e p r o t e c t i o n .

Figure 4 shows curves t h a t a r e t y p i c a l of t h e temperature r i s e a t t h e i n t e r f a c e between foam and p r o t e c t i o n f o r p l a s t i c foams p r o t e c t e d with gypsum o r magnesium oxychloride. I t

i s

seen t h a t t h e temperatures a t t h e v a r i o u s measuring p o i n t s remain approximately c o n s t a n t f o r a c e r t a i n time, probably because of dehydration, and then s t a r t t o i n c r e a s e r a p i d l y .

I n Figure 5 , t y p i c a l curves a r e shown f o r t h e temperature r i s e between foam and p r o t e c t i o n f o r p l a s t i c foams p r o t e c t e d with plywood. In t h i s c a s e , t h e temperature curve does n o t remain

c o n s t a n t ; t h e r e i s a gradual i n c r e a s e i n temperature u n t i l t h e p o i n t of f a i l u r e i s reached. A s u b s t a n t i a l i n c r e a s e i n t h e r a t e of

temperature r i s e s t a r t e d a few minutes a f t e r reaching t h e f a i l u r e temperature. This i n c r e a s e was probably caused by t h e f a c t t h a t t h e plywood was charred through t o t h e foam.

ROOM

CORNER

FIRE TEST

'1'0 o b t a i n information on t h c behnviour of t h e t e s t e d m a t e r i a l s under c o n d i t i o n s met with i n p r a c t i c e , t e s t s were c a r r i e d o u t i n which t h e growth of a f i r e i n a c o r n e r of a room was simulated. Two t e s t s were performed, one with p r o t e c t e d 1 - i n . p o l y s t y r e n e foam and one with p r o t e c t e d 1 - i n . polyurethane foam.

In

both t e s t s , 3/8-in. r e g u l a r gypsum board was used a s p r o t e c t i v e m a t e r i a l . The boards forming t h e w a l l s of t h e room c o r n e r were each 8 f t high and

4 f t wide. The dimensions o f t h e c e i l i n g were 4 f t by 4 f t . A t t h e c o r n e r s t h e r e was a b u t t j o i n t between t h e edge of one board and t h e f a c e of t h e o t h e r . A l l j o i n t s were taped and covered with a c o a t of premixed j o i n t compound over t h e t a p e . I n t h e t e s t with p o l y s t y r e n e foam t h e specimen with an a s b e s t o s board backing was n a i l e d t o a wooden frame. In t h e t e s t with polyurethane foam, a rubber m a s t i c adhesive was used t o f a s t e n t h e a s b e s t o s board backing t o one s i d e o f t h e i n s u l a t i o n and gypsum board t o t h e o t h e r . The adhesive was a p p l i e d along t h e edges of t h e foam and along t h e diagonals over a width of approximately 2 _{i n .}

The i g n i t i o n s o u r c e , a n a t u r a l gas burner, c o n s i s t e d o f a s a n d - f i l l e d cone-shaped s t e e l c o n t a i n e r , with an a r e a o f 95 sq i n . a t t h e t o p , 50 s q i n . a t t h e bottom and a h e i g h t o f 6-5/8 i n . The

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b u r n e r produced h e a t a t a r a t e o f 5000 Btu/min., which was h i g h e r t h a n t h e h e a t u s u a l l y r e l e a s e d d u r i n g experimental waste p a p e r b a s k e t f i r e s 3 .

Temperatures were measured w i t h thermocouples, a t s e v e r a l l o c a t i o n s above t h e b u r n e r and a t t h e i n t e r f a c e between foam and p r o t e c t i o n .

ROOM CORNER TEST RESULTS

R e s u l t s o f t h e t e s t on p r o t e c t e d p o l y s t y r e n e foam a r e shown i n Figure 6. No n o t i c e a b l e c o n t r i b u t i o n t o f i r e growth by t h e

p o l y s t y r e n e foam was observed d u r i n g t h e exposure. A f t e r 21 minutes

t h e t e s t was ended. A s shown i n F i g u r e 6c o n l y a s m a l l p a r t of t h e gypsum board, t h a t p a r t i n d i r e c t c o n t a c t w i t h t h e b u r n e r flame, was a f f e c t e d by t h e f i r e . R e s u l t s were s i m i l a r d u r i n g t h e t e s t on

p r o t e c t e d p o l y u r e t h a n e foam. These r e s u l t s a r e shown i n F i g u r e 7.

A comparison o f t e m p e r a t u r e s measured a t t h e i n t e r f a c e foam-protection ( F i g s . 8 and 9 ) showed t h a t t h e average t e m p e r a t u r e measured d u r i n g t h e f u r n a c e t e s t s approximately f o l l o w s t h e same c o u r s e a s t h e i n t e r f a c e t e m p e r a t u r e a t t h e h o t t e s t s p o t , i . e . ,

o p p o s i t e t h e c e n t r e o f t h e b u r n e r flame, d u r i n g t h e room c o r n e r t e s t . The flame t e m p e r a t u r e i t s e l f , measured 2 f t above ground l e v e l , was approximately 1 7 0 0 ' ~ . Temperature measurements a t v a r i o u s l o c a t i o n s d u r i n g t h e room c o r n e r t e s t s showed t h a t 2 f t from t h e v e r t i c a l j o i n t t h e t e m p e r a t u r e r i s e a t t h e i n t e r f a c e was i n s i g n i f i c a n t up t o t h e end

of t h e t e s t . CONCLUSIONS

Comparison o f r e s u l t s of t e s t s on p o l y s t y r e n e and polyure- t h a n e foam p r o t e c t e d with 3 / 8 - i n . r e g u l a r gypsum board showed t h a t t h e average t e m p e r a t u r e r i s e a t t h e i n t e r f a c e foam-protection, measured d u r i n g f u r n a c e t e s t s , i s s i m i l a r t o t h e i n t e r f a c e t e m p e r a t u r e r i s e a t t h e h o t t e s t s p o t d u r i n g room c o r n e r t e s t s .

An average t e m p e r a t u r e r i s e o f 250 F deg a t t h e i n t e r f a c e foam-protection was chosen a s t h e c r i t e r i o n of f a i l u r e o f t h e

p r o t e c t i o n . For t h e t e s t e d 3 / 8 - i n . gypsum board t h i s t e m p e r a t u r e r i s e was reached i n about 10 minutes a f t e r t h e s t a r t o f t h e f u r n a c e t e s t . I n t h e room c o r n e r t e s t s with t h e same p r o t e c t i o n , o n l y t h a t p a r t o f t h e foam o p p o s i t e t o t h e b u r n e r flame c o n t r i b u t e d t o t h e f i r e . No s i g n i f i c a n t c o n t r i b u t i o n o f t h e p l a s t i c foam was observed from o t h e r p a r t s up t o t h e t i m e o f t e r m i n a t i o n o f t h e t e s t s , which was 21 minutes a f t e r t h e s t a r t i n t h e c a s e o f p o l y s t y r e n e foam and

17 minutes i n t h e c a s e o f p o l y u r e t h a n e foam. The method o f f a s t e n i n g , glued o r mechanical, was n o t important a s o n l y a s m a l l p a r t of t h e board c l o s e t o t h e b u r n e r flame was a f f e c t e d by t h e h e a t exposure.

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The results indicate that the time of failure determined by

the furnace test is a conservative estimate of the time that is

available to evacuate the fire area before the foam insulation starts

to contribute significantly to fire growth. For example, a rating of

10 minutes by the furnace test should reasonably assure that a given

protected foam insulation will not contribute to the fire for about

20 minutes or more, which is normally more than adequate for evacuation.

REFERENCES

1

_{National Building Code of Canada, 1975, Associate Committee on}

the National Building Code, National Research Council of

Canada, Ottawa.

2

_{Standard Methods of Fire Tests for Surface Burning}

Characteristics of Building Materials, ASTM Designation

E84-70, 1974, Annual Book of ASTM Standards, Part 18,

p. 574-582.

3

_{Williamson, R.B. and Baron, F.M., A Corner Fire Test to}

Simulate Residential Fires,Journal of Fire and Flammability,

Vol. 4, 1973, p. 99-105.

4

_{Standard Methods of Fire Tests of Building Construction and}

Materials, ASTM Designation E119-73, 1974, Annual Book of

ASTM Standards, Part 18,

p. 610-628.

5

Blanchard, J.A.C. and Harmathy, T.Z., Small-Scale Fire Test

Facilities of the National Research Council, National

Research Council of Canada, Division of Building Research,

Fire Study No. 14, Ottawa, 1964.

6

Sumi,

K.,

National Research Council of Canada, Division of

Building Research, Private Communication.

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F I G U R E 1

T Y P I C A L C U R V E O F T E M P E R A T U R E I N R O O M D U R I N G F I R E

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TEST S P E C I M E N C L A M P I N G BARS F U R N A C E H E A T I N G E L E M E N T S I N C O N E L P L A T E C H A M B E R V I E W P O R T S F I G U R E 2 C R O S S S E C T I O N O F TEST F U R N A C E DR s a a i - z

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2 4 6 ₈ TIME, h F I G U R E 3 S T A N D A R D T E M P E R A T U R E - T I M E C U R V E A C C O R D I N G T O A S T M E 1 1 9 - 7 3 B R S S 6 1 - 3

(15)

C A T I O N O F T H E R M O C O U P L E S A T I N T E R F A C E I N T E R F A C E 3 1 0 15 T I M E , M I N F I G U R E 4 T E M P E R A T U R E S M E A S U R E D I N F U R N A C E A N D A T I N T E R F A C E F O A M A N D P R O T E C T I O N ( F O A M : P O L Y U R E T H A N E A ; P R O T E C T I O N : I N . G Y P S U M B O A R D ) BI 6 3 S l - +

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L O C A T I O N O F T t i l R M O C O U P L E S A T I N T F R F A C F A S T M 1 1 \ 9 - 7 3 S T A N D A R D C U R V E A V E R A G E % F U R N A C E T E M P E R A T U R E I N T E R F A C E T E M P E R A T U R E S U 5 10 15 T I M E , M I N F I G U R E 5 T E M P E R A T U R E S M E A S U R E D I N F U R N A C E A N D A T I N T E R F A C E F O A M A N D P R O T E C T I O N ( F O A M : P O L Y U R E T H A N E A ; P R O T E C T I O N : $ I N . F I R P L Y W O O D ) B R 5 3 1 1 -I

(17)

F i g u r e 6 P o l y s t y r e n e foam p r o t e c t e d w i t h 318 i n . gypsum b o a r d I

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( r e g u l a r ) . N a i l s a r e u s e d

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t o a t t a c h specimen F i g u r e 6 a S t a r t o f t h e t e s t

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P F i g u r e 6b A f t e r 20 m i n u t e s

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Figure 6c

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F i g u r e 7 P o l y u r e t h a n e foam A p r o t e c t e d w i t h 318 i n . gypsum b o a r d ( r e g u l a r ) . Adhesive i s u s e d t o a t t a c h specimen F i g u r e 7 a S t a r t o f t h e t e s t 7, .. I F i g u r e 7b

t

r .

I A f t e r 1 5 m i n u t e s

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F i g u r e 7c

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T I M E . M I N I F I G U R E 8 T E M P E R A T U R E S M E A S U R E D A T I N T E R F A C E F O A M A N D P R O T E C T I O N ( F O A M : P O L Y S T Y R E N E ; P R O T E C T I O N : 3 1 8 I N . G Y P S U M B O A R D ) 8 R 5 3 1 1 - 5 .

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F I G U R E 9 T E M P E R A T U R E S M E A S U R E D A T I N T E R F A C E F O A M A N D P R O T E C T I O N ( F O A M : P O L Y U R E T H A N E : P R O T E C T I O N : 318 I N . G Y P S U M B O A R D ) B R 5 2 8 1 - 1 1 4 I I I I 1 1 1 I

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- - - - F U R N A C E I E S T - ( A V E R A G E T E M P E R A l U K E I\ - R O O M C G R N E R TEST ( H O T T E S T S P O T ) -

1 I

2 4 h 8 ₁₀ 1 2