Chapter 34
Fire Hazard in a Room Due to a Fire Starting in a Plenum
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Effect of Poly(vinyl chloride) Wire Coating F. Merrill Galloway and Marcelo M. Hirschler BFGoodrich Technical Center, P.O. Box 122, Avon Lake, OH 44012 An issue of interest is the contribution to f i r e hazard in a room from products in a plenum space above i t . This contribution can result from two scenarios: f i r e in the room or f i r e in the plenum. The products being addressed here are PVC e l e c t r i c a l products contained in a plenum. The f i r s t scenario involves a f i r e starting in the room. Three room dimensions and two c e i l i n g materials were analysed; the products were PVC conduit (rigid and ENMT, semi-rigid; 100 m of either) and PVC wire coating (400 m). It was found that the amount of energy needed for the room f i r e to cause thermal decomposition of the PVC products in the plenum was larger than that needed to take the room to flashover. Furthermore, if the PVC products did eventually decompose or burn, somehow, they would cause a lethal smoke concentration only significantly later than a lethal (by toxicity) atmosphere had already been created by the f i r e i t s e l f . Thus, the PVC products did not add any significant f i r e hazard to that caused by the room f i r e . The next scenario is more complex: i t involves a f i r e starting in a plenum and has been analysed only for wire coating. Calculations were made, for many f i r e scenarios, in which the f i r e hazard model F . A . S . T . was used to simulate hazard to occupants of a standard room following a f i r e starting in a plenum above it. A t o t a l of 400 m of PVC wire coating was assumed to be present in the plenum. Its decomposition was made a function of the plenum temperature achieved. The f i r e ranged 0097-6156/90/0425-0592$06.00/0 © 1990 American Chemical Society
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
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34.
GALLOWAY & HIRSCHLER
Effect ofPoly (vinylchloride) Wire Coating
between RHR of 50 and 500 kW; the heat of combustion of the f i r e varied between a standard value (20 kJ/g) and that of methane (57 kJ/g). Various vent connections between compartments and surroundings were used. The plenum temperature was never enough to decompose all the PVC wire coating. If the plenum was vented to the surroundings, almost no smoke entered the room. In an unvented plenum smoke entered the room but the f i r e burnt for a short period only: the level of oxygen was not enough for f u l l combustion. In extreme cases the f i r e generated enough heat for an untenable atmosphere in the room. In almost a l l single plenum cases studied the smoke flowing into the room was insufficient to generate a concentration lethal to man. Therefore, using such low heat release PVC wire coating products did not cause a significant increase in the f i r e hazard to occupants. I n o f f i c e b u i l d i n g s i t i s v e r y common t o h a v e p l e n u m s , i . e . s p a c e s a b o v e rooms where t h e a i r h a n d l i n g s y s t e m i s l o c a t e d , t o g e t h e r w i t h e l e c t r i c a l w i r e s and c a b l e s , as w e l l a s a b u n d a n t wood a n d o t h e r c o n s t r u c t i o n m a t e r i a l s . T h e s e c o n c e a l e d s p a c e s a r e u s u a l l y c a . 1 m (3 f t ) h i g h a n d a r e i n v i s i b l e f r o m t h e room b e l o w . I n t h e 1 9 8 0 » s y e a r s t h e r e h a s b e e n some c o n t r o v e r s y about t h e e f f e c t o f f i r e s i n v o l v i n g combustible products c o n t a i n e d i n such concealed spaces. This addresses the room-plenum s c e n a r i o b o t h when a f i r e s t a r t s i n t h e room and when a f i r e s t a r t s i n t h e p l e n u m a n d i n v e s t i g a t e s i t s s p r e a d i n t o t h e room b e l o w . In r e c e n t y e a r s t h e r e h a s b e e n much c o n t r o v e r s y s u r r o u n d i n g t h e i m p a c t o f smoke t o x i c i t y f o l l o w i n g a f i r e . T h i s h a s i n c l u d e d d i s c u s s i o n s r e g a r d i n g means t o m e a s u r e t o x i c p o t e n c y , b y one o f a v a r i e t y o f s m a l l - s c a l e methods, and how t o u s e t h e s e r e s u l t s t o e v a l u a t e f i r e hazard. T h e r e h a s b e e n , i n p a r t i c u l a r , much s p e c u l a t i o n r e g a r d i n g t h e h a z a r d s due t o c e r t a i n p l a s t i c s , t y p i c a l l y p o l y ( v i n y l chloride) (PVC). The present paper w i l l deal with this issue i n several stages. (1) A d d r e s s t h e i s s u e o f PVC f i r e p r o p e r t i e s , i n c l u d i n g smoke t o x i c i t y a n d h y d r o g e n c h l o r i d e d e c a y . (2) D e s c r i b e measurements o f mass l o s s r a t e s o f v a r i o u s electrical PVC products, by thermoanalytical experiments. (3) A d d r e s s t h e c o n c e a l e d s p a c e s c e n a r i o s u s e d . (4) I n v e s t i g a t e t h e f i r e h a z a r d i n a room d u e t o t h e b u r n i n g o f PVC e l e c t r i c a l p r o d u c t s i n a p l e n u m s p a c e
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
593
594
FIRE AND POLYMERS above i t , when a fire starts i n t h e compartment underneath. (5) I n v e s t i g a t e t h e f i r e h a z a r d i n a room due t o t h e b u r n i n g o f PVC w i r e c o a t i n g i n a p l e n u m s p a c e a b o v e i t , when t h e f i r e s t a r t s i n t h e plenum.
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Fire
Properties of Poly(Vinyl Chloride)
O t h e r p a p e r s i n t h i s volume a d d r e s s t h e i m p o r t a n c e o f a v a r i e t y o f f i r e p r o p e r t i e s on f i r e h a z a r d , i n p a r t i c u l a r the r e l a t i v e importance (or l a c k o f i t ) o f t o x i c potency o f smoke ( e . g . R é f . [ 1 ] ) . PVC i s u n i q u e among commodity m a t e r i a l s i n t h a t i t c o n t a i n s c h l o r i n e and, t h u s , p r o d u c e s h y d r o g e n chloride (HC1) when i t decomposes o r b u r n s [ 2 , 3 ] . The fire properties o f PVC h a v e been put into p e r s p e c t i v e r e c e n t l y [4, 5 ] . They show t h a t PVC i s a polymer with a high ignition temperature and low flammability. F u r t h e r m o r e , PVC p r o d u c t s a r e a s s o c i a t e d w i t h a low r a t e o f h e a t r e l e a s e a s w e l l a s l i t t l e total heat released [4-9]. T h i s w i l l depend, c l e a r l y , on t h e type of product, since plasticised PVC p r o d u c t s a r e o b v i o u s l y more f l a m m a b l e t h a n r i g i d o n e s . Undoubtedly, f i r e hazard i s p a r t i a l l y a s s o c i a t e d w i t h t h e t o x i c i t y o f t h e smoke i t s e l f . The smoke o f a v a r i e t y of common m a t e r i a l s , a s m e a s u r e d e . g . by t h e NBS c u p furnace t o x i c i t y test [ 1 0 ] , h a s r e c e n t l y b e e n compared w i t h t h e i n t r i n s i c t o x i c p o t e n c y o f o t h e r p o i s o n s and o f t o x i c gases, as w e l l as w i t h t o x i c i t y c a t e g o r i e s [11]. I t h a s b e e n shown t h a t t o x i c i t y i s a r e l a t i v e l y m i n o r f a c t o r because there i s very little difference between t h e i n t r i n s i c t o x i c p o t e n c y o f t h e smoke o f t h e m a j o r i t y o f common m a t e r i a l s , w i t h v e r y few e x c e p t i o n s . D e t a i l e d s t u d i e s h a v e a l s o b e e n made on t h e t o x i c i t y o f HC1, a n i r r i t a n t g a s o f t e n p r e s e n t i n f i r e s . I t does n o t c a u s e baboon o r r a t i n c a p a c i t a t i o n up t o v e r y h i g h exposure doses which a r e s u f f i c i e n t (or very close) t o cause e v e n t u a l death [ 1 2 ] . Furthermore, a r e c e n t study has shown t h a t the e f f e c t s of i r r i t a n t s are heavily d e p e n d e n t on t h e a n i m a l model u s e d [ 1 3 ] . I n t e r e s t i n g l y , t h e mouse i s much more s e n s i t i v e t o HC1 t h a n t h e r a t [ 1 3 - 1 6 ] , I n t u r n , however, t h e r a t w o r k s as a g o o d model f o r a p r i m a t e , a s f a r a s l e t h a l i t y due t o HC1 i s c o n c e r n e d [17, 1 8 ] . T h i s i s i m p o r t a n t b e c a u s e a l l r o d e n t s (mice and r a t s ) a r e o b l i g a t e n o s e b r e a t h e r s , w h i l e p r i m a t e s c a n a l s o b r e a t h e t h r o u g h t h e i r mouths, a n d i t h a s been speculated that this would make rodents less s e n s i t i v e t o HC1 t h a n p r i m a t e s [ 1 9 ] . The r e l e v a n c e o f a l l t h i s t o t h e p r e s e n t p a p e r i s t h a t t h e t o x i c p o t e n c y o f PVC smoke o r o f HC1 a r e f a i r l y s i m i l a r t o t h o s e o f o t h e r smoke o r o f c a r b o n m o n o x i d e (CO) respectively.
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
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34.
GALLOWAY & HIRSCHLER
Effect ofPoly(vinyl chloride) Wire Coating
A l a r g e number o f s t u d i e s h a v e a l s o b e e n done t o i n v e s t i g a t e t h e l i f e t i m e o f HC1 i n a f i r e atmosphere [20-24]. T h e s e s t u d i e s h a v e shown t h a t HC1 r e a c t s v e r y r a p i d l y w i t h most common c o n s t r u c t i o n s u r f a c e s (cement b l o c k , c e i l i n g t i l e , gypsum b o a r d , e t c . ) s o t h a t t h e peak atmospheric c o n c e n t r a t i o n f o u n d i n a f i r e i s much l e s s t h a n w o u l d h a v e been p r e d i c t e d f r o m t h e c h l o r i n e c o n t e n t of the burning material. Furthermore, this peak c o n c e n t r a t i o n s o o n d e c r e a s e s a n d HC1 d i s a p p e a r s c o m p l e t e l y from t h e atmosphere. These c o n s i d e r a t i o n s a r e i n c l u d e d here because i n t h e d i s c u s s i o n t h a t f o l l o w s HC1 d e c a y w i l l be i g n o r e d , t o f a c i l i t a t e the calculations. HC1 d e c a y i s a l s o i m p o r t a n t when m e a s u r i n g PVC t o x i c p o t e n c y , because t h e w a l l s o f e x p o s u r e chambers a r e made o f n o n - s o r p t i v e m a t e r i a l s , where s u c h d e c a y i s m i n i m i s e d . In t h i s connection i t i s worth p o i n t i n g out t h a t t h e h i g h e s t c o n c e n t r a t i o n o f HCl f o u n d when f i r e f i g h t e r s e n t e r e d b u i l d i n g s a c t u a l l y on f i r e was c a . 280 ppm [25, 2 6 ] . Mass L o s s
R a t e s o f PVC
Products
Table I presents the r e s u l t s of "isothermal" simultaneous t h e r m o a n a l y t i c a l (STA) r u n s , a t 573 Κ a n d 773 K, f o r a l l three products. S i m i l a r data, a t a f i x e d heating r a t e i s shown i n T a b l e I I . One o f t h e c r u c i a l p a r a m e t e r s i s t h e t e m p e r a t u r e o f maximum w e i g h t l o s s r a t e , c o r r e s p o n d i n g t o t h e t i m e when d e h y d r o c h l o r i n a t i o n o f PVC s t a r t s b e c o m i n g important. T h i s temperature i s c l o s e t o 573 Κ i n a l l cases. In f a c t , a t a r e l a t i v e l y f a s t h e a t i n g r a t e , almost no d e c o m p o s i t i o n o c c u r s a t t e m p e r a t u r e s u n d e r 563 K. If t h e m a t e r i a l s a r e h e a t e d a t 573 Κ f o r a p r o l o n g e d p e r i o d , c o m p l e t e d e h y d r o c h l o r i n a t i o n t a k e s p l a c e , b u t no f u r t h e r s t a g e s o f PVC d e c o m p o s i t i o n o c c u r . None o f t h e three materials investigated decomposes completely until a t e m p e r a t u r e o f c a . 773 Κ i s a t t a i n e d . Even t h e n o n l y a c e r t a i n f r a c t i o n o f t h e e n t i r e mass o f t h e s a m p l e s i s v o l a t i l i s e d , due t o t h e p r e s e n c e o f i n o r g a n i c f i l l e r s i n t h e i r composition. The a v e r a g e r a t e o f mass l o s s i s c a l c u l a t e d f r o m t h e amount o f mass l o s t a n d t h e c o r r e s p o n d i n g t i m e p e r i o d . The c a l c u l a t i o n s i n T a b l e I a t 573 Κ r e p r e s e n t t h e a v e r a g e mass l o s s o f i s o t h e r m a l d e h y d r o c h l o r i n a t i o n . Thus, t h e v a l u e s i n T a b l e I (3.4 %/min f o r b l u e c o n d u i t , 2.9 %/min f o r g r e y c o n d u i t and 2.3 %/min f o r w i r e c o a t i n g ) r e p r e s e n t a r e a s o n a b l e e s t i m a t e o f t h e mass l o s s r a t e o f t h e PVC p r o d u c t s i n a f i r e , a t a t e m p e r a t u r e n o t e x c e e d i n g 563 K. Concealed
Space
Scenarios
A few r e c e n t e v e n t s make i t p a r t i c u l a r l y i n t e r e s t i n g t o v a l u a t e t h e f i r e h a z a r d r e s u l t i n g f r o m t h e b u r n i n g o f PVC m a t e r i a l s , when t h e y a r e p r e s e n t i n a p l e n u m . These i n c l u d e t h e r e c e n t r e g u l a t i o n s promulgated i n New Y o r k S t a t e r e g a r d i n g t h e c r e a t i o n o f a d a t a b a s e f o r smoke
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
595
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
wt l o s s
255
First
T (K)
Max DTG
(%)
(mg/min)
(%)
(mg/min)
T h i r d wt l o s s
Max DTG
S e c o n d wt l o s s
(%/min) loss)
(%/min)
Max DTG
(%)
(mg/min)
A v e r a g e DTG ( f i r s t wt
Κ
(%)
Max DTG
U
wt l o s s
Total
Top T e m p e r a t u r e
Table I.
2.0
3.4
10.8
2.6
290
49.0
51.0
573
0.3
14.6
1.8
20.5
14.3
34.2
7.5
279
56.0
85.9
873
ENMT C o n d u i t
2.9
13.1
3.1
290
50.1
50.1
573
Rigid
Results of "isothermal"
0.06
22.9
0.2
18.7
12.5
29.3
6.1
269
47.7
85.5
873
Conduit
STA r u n s
-
-
-
-
2.3
7.9
1.9
282
49.9
49.9
573
Wire
0.04
6.5
0.9
8.8
10.5
35.6
7.8
46.6
62.0
873
Coating
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34.
GALLOWAY & HIRSCHLER
Effect ofPoly(vinyl chloride) Wire Coating
t o x i c i t y of b u i l d i n g products [27]. The p r o d u c t s t h a t were t e s t e d i n t h e f i r s t y e a r ( e l e c t r i c a l ) a r e o f t e n f o u n d behind f i r e rated w a l l s or c e i l i n g s . An example o f a c a l c u l a t i o n o f t h i s t y p e h a s b e e n made f o r f l u o r i n a t e d w i r e c o a t i n g s [28] and f o r PVC e l e c t r i c a l m a t e r i a l s [29] and, a n o t h e r one, f o l l o w i n g a d i f f e r e n t p r o c e d u r e and a d i f f e r e n t s c e n a r i o , f o r PVC-based e l e c t r i c n o n - m e t a l l i c (ENMT, s e m i - r i g i d ) c o n d u i t [ 3 0 ] . The p h i l o s o p h y u s e d i n r e f e r e n c e s [28] and [29] i s t h a t f i r e h a z a r d i s h i g h e r i f t h e time t o r e a c h a l e t h a l atmosphere i s lower. The scenarios investigated here involve various room-plenum c o n f i g u r a t i o n s . The room h a s a standard opening c o r r e s p o n d i n g t o the s i z e of a normal door (2.03 χ 0.74 m). The rooms i n t h e f i r s t p a r t o f t h e s t u d y ( f i r e i n t h e room) were o f d i m e n s i o n s w h i c h m i g h t r e p r e s e n t , a p p r o x i m a t e l y , a s m a l l w a r e h o u s e (10.0 χ 10.0 χ 3.0 m), a bedroom ( 3 . 7 x 3 . 7 x 2 . 7 m) and an o f f i c e (2.5 χ 2.5 χ 2.5 m) and t h e p l e n u m h e i g h t i s 1.0 m t h r o u g h o u t . In each c a s e , two different c e i l i n g m a t e r i a l s were c o n s i d e r e d (viz. gypsum w a l l b o a r d (GB) and ceiling tile (CT)). Furthermore, the i n t e n s i t y of heat of combustion of the f u e l i n v o l v e d i n c a u s i n g t h e f i r e was s e t a t b o t h 20 k J / g and 40 k J / g , t h u s c o v e r i n g t h e r a n g e s t y p i c a l f o r most materials. I t was assumed t h a t t h e smoke was i n s t a n t a n e o u s l y d i s t r i b u t e d among e i t h e r t h e room and p l e n u m o r t h e room and p l e n u m p l u s a n o t h e r t h r e e rooms i d e n t i c a l i n s i z e t o t h e b u r n room. A l l room w a l l s were assumed t o be made o f gypsum w a l l b o a r d and a l l f l o o r s o f c o n c r e t e . This part w i l l p r e s e n t , f o r e a c h c a s e , an a s s e s s m e n t of the time required to achieve an untenable atmosphere, as a consequence of the exclusive presence, in the c o r r e s p o n d i n g plenum, o f P V C - c o a t e d e l e c t r i c a l w i r e (400 m) , o f P V C - b a s e d r i g i d c o n d u i t (100 m) and o f P V C - b a s e d e l e c t r i c a l n o n - m e t a l l i c ENMT, s e m i - r i g i d , c o n d u i t (100 m). T h e s e t i m e s w i l l be compared w i t h t h e t i m e s a t w h i c h s u c h an u n t e n a b l e a t m o s p h e r e i s g e n e r a t e d due t o t h e t o x i c i t y o f t h e m a t e r i a l s b u r n i n g i n t h e room, a s s u m i n g them t o be o f n o r m a l t o x i c p o t e n c y , s i m i l a r t o t h a t o f an o r d i n a r y wooden p r o d u c t ( e . g . D o u g l a s f i r ) . The rooms i n t h e s e c o n d p a r t o f t h e s t u d y a r e a l l o f t h e same s i z e , v i z . 3.7 χ 3.7 χ 2.7 m. The p l e n u m s b e i n g c o n s i d e r e d a r e e i t h e r one w i t h t h e same f l o o r s i z e and 1.0 m h e i g h t o r one w i t h 3 t i m e s t h e f l o o r s i z e (3 p l e n u m configuration) o r 10 t i m e s t h e f l o o r size (10 p l e n u m configuration). The o n l y c e i l i n g m a t e r i a l c o n s i d e r e d i s gypsum b o a r d and t h e o n l y p r o d u c t b e i n g i n v e s t i g a t e d i s a PVC w i r e c o a t i n g f i r e r e t a r d e d t o g i v e v e r y low heat r e l e a s e and f l a m e s p r e a d . In t h i s case, the f i r e s t a r t s i n a p l e n u m and t h e work i n v e s t i g a t e s w h e t h e r i t s p r e a d s into the room below in terms of i t s effects on temperature, smoke l a y e r l e v e l s and c o n c e n t r a t i o n s of t o x i c g a s e s , m a i n l y c a r b o n monoxide, i n b o t h room and plenum.
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
597
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990. 57.6
DTG
DTG
S e c o n d wt
loss
(%)
(%/min) loss)
(K)
(%/min)
A v e r a g e DTG ( f i r s t wt
Temp max
1%
22.9
1.7
546
13.5
(%)
92.0
5
Max
loss
(%)
K/min
16.8
7.4
578
33.3
500
57.8
91.9
20
ENMT C o n d u i t
11.1
1.3
555
8.0
528
52.9
86.9
5
Rigid
17.0
6.1
574
31.1
575
53.2
87.6
20
Conduit
rate
15.1
1.1
568
8.6
595
50.7
77.6
5
12. 1
15.6
584
25.3
50.2
75.4
20
Wire Coating
R e s u l t s o f STA r u n s a t 5 a n d 20 K/min h e a t i n g
546
wt
First
loss
rate
II.
T ( K ) 522
wt
Total
Heating
Table
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00
in
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
(%/min)
(%/min)
2.3
818
A v e r a g e DTG (%/min) 1.1 ( f i r s t t o t h i r d wt 1. s s e s )
727
2.4
24.2
1.1
(%/min) loss)
1.0
13.9
losses)
5.6
3.0
713
7.2
0.5
A v e r a g e DTG ( t h i r d wt
Temp max DTG (K)
Max DTG
(%)
1.3
A v e r a g e DTG (%/min) ( f i r s t a n d s e c o n d wt
T h i r d wt l o s s
0.9
696
1.5
A v e r a g e DTG (%/min) ( s e c o n d wt l o s s )
Temp max DTG (K)
Max DTG
1.1
1.0
787
1.9
22.9
1.2
0.9
712
2.7
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600
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Fire
FIRE AND starting
POLYMERS
i n t h e Room
For t h e a n a l y s i s , a s t e a d y - s t a t e f i r e was assumed. A s e r i e s o f e q u a t i o n s was t h u s u s e d t o c a l c u l a t e v a r i o u s temperatures and/or heat r e l e a s e r a t e s per u n i t s u r f a c e , b a s e d on a s s i g n e d i n p u t v a l u e s . T h i s s e r i e s o f e q u a t i o n s i n v o l v e s f o u r c o n v e c t i v e h e a t t r a n s f e r and two c o n d u c t i v e heat t r a n s f e r processes. These a r e : (a) c o n v e c t i v e t r a n s f e r f r o m f i r e t o u p p e r room l a y e r (b) c o n d u c t i v e t r a n s f e r t h r o u g h s u s p e n d e d c e i l i n g t o plenum f l o o r (c) convective transfer from suspended ceiling to plenum a i r (d) c o n v e c t i v e t r a n s f e r t o p l e n u m c e i l i n g (e) c o n d u c t i v e t r a n s f e r t h r o u g h c o n c r e t e p l e n u m c e i l i n g slab ( f ) c o n v e c t i v e t r a n s f e r t o a i r a b o v e plenum (ambient temperature) The h e a t r e l e a s e r a t e n e c e s s a r y f o r f l a s h o v e r was c a l c u l a t e d , f r o m t h e e q u a t i o n g i v e n by Q u i n t i e r e e t a l . [31]. The s e r i e s o f e q u a t i o n s i s t h e n s o l v e d , w i t h t h e assumption t h a t the temperature i n c r e a s e f o r f l a s h o v e r i s 500 Κ ( l e a d i n g t o an u p p e r l e v e l t e m p e r a t u r e o f T : 795 K) and t h e p l e n u m t e m p e r a t u r e f o r d e c o m p o s i t i o n o f t h e PVC p r o d u c t s i s 573 K. The r e s u l t s i n T a b l e I I I show t h a t a much more i n t e n s e f i r e i s r e q u i r e d , i n a l l c a s e s , t o c a u s e t h e PVC p r o d u c t s t o u n d e r g o d e h y d r o c h l o r i n a t i o n t h a n t o t a k e t h e room t o f l a s h o v e r . T h u s , t h e h e a t r e l e a s e d by this fire at flashover is insufficient to d e h y d r o c h l o r i n a t e t h e PVC p r o d u c t s i n t h e plenum, f o r any of the s c e n a r i o s . T h e r e f o r e , t h e o c c u p a n t s o f t h e room w i l l succumb b e f o r e t h e r e i s an e f f e c t due t o t h e p l e n u m PVC p r o d u c t s . I t i s of i n t e r e s t t o c a l c u l a t e , too the time r e q u i r e d f o r b o t h t h e f i r e i t s e l f and t h e t h e r m a l d e c o m p o s i t i o n o f t h e p l e n u m PVC p r o d u c t s t o p r o d u c e a l e t h a l a t m o s p h e r e . Table I I I p r e s e n t s such r e s u l t s f o r the f i r e , f o r heats of c o m b u s t i o n o f 20 k J / g and 40 k J / g , a r a n g e t y p i c a l o f most fires. In o r d e r t o c a r r y out t h i s c a l c u l a t i o n i t i s assumed t h a t t h e smoke i s d i s t r i b u t e d i n s t a n t a n e o u s l y throughout the volume being c o n s i d e r e d , one or four room-plenums. The barriers r e p r e s e n t e d by walls or transport processes are ignored. The t o x i c p o t e n c y u s e d f o r t h e f i r e i s a m i n i m a l v a l u e , an L C o f 40 mg/1 for a 30 min e x p o s u r e i n t h e NBS smoke t o x i c i t y t e s t , i n t h e n o n - f l a m i n g mode. T h i s c o u l d be r e p r e s e n t a t i v e o f a v a r i e t y o f m a t e r i a l s ( e . g . wood) and i s w i t h i n t h e n o r m a l range of t o x i c p o t e n c i e s . In order to calculate the "time to lethal c o n c e n t r a t i o n " t h e c o n c e n t r a t i o n o f smoke ( p e r u n i t t i m e ) is f i r s t calculated. Then t h e t o t a l amount o f smoke ( i n c o n c e n t r a t i o n p e r u n i t t i m e ) i s c a l c u l a t e d f r o m t h e mass o f m a t e r i a l (and, i n t h e c a s e o f t h e PVC p r o d u c t s , t h e percentage of the weight of the product t h a t can be v o l a t i l i s e d , a s s e e n f r o m t h e STA r e s u l t s ) . To t h e r a t i o UL
? 0
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
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34.
GALLOWAY & HIRSCHLER
Effect of Poly (vinyl chloride) Wire Coating
o f t h e t o x i c p o t e n c y t o t h e amount o f smoke i s a d d e d t h e time f o r thermal p e n e t r a t i o n of hot gases through the ceiling and t h e 30 min exposure time t h a t the toxic potency r e f e r s t o . The c a l c u l a t i o n s a r e a l l r e p e a t e d f o r t r a n s p o r t o f t h e smoke o v e r f o u r room-plenums o f t h e same size. Table I I I presents the r e s u l t s of c a l c u l a t i n g the " t i m e t o l e t h a l c o n c e n t r a t i o n " f o r e a c h one o f t h e PVC products investigated. The t o x i c p o t e n c y v a l u e s u s e d f o r a l l t h e m a t e r i a l s a r e b a s e d on 30 min e x p o s u r e s i n t h e NBS cup f u r n a c e t o x i c i t y t e s t , i n t h e N o n - F l a m i n g mode, t h e one most r e l e v a n t t o t h i s s c e n a r i o . I t i s c l e a r t h a t the "time t o l e t h a l c o n c e n t r a t i o n " f o r t h e smoke f r o m any o f t h e PVC p r o d u c t s i n t h e plenum, i n a l l t h e s i x s c e n a r i o s c o n s i d e r e d , i s much l o n g e r t h a n t h e t i m e r e q u i r e d f o r t h e f u e l i n t h e room i t s e l f t o c a u s e a l e t h a l c o n c e n t r a t i o n i n t h e same s c e n a r i o . T h i s i n d i c a t e s c l e a r l y t h a t t h e s e PVC plenum p r o d u c t s w i l l not cause a s e r i o u s f i r e hazard concern u n t i l w e l l a f t e r t h e f i r e i t s e l f h a s r e a c h e d f l a s h o v e r c o n d i t i o n s and has l o n g s i n c e caused l e t h a l c o n c e n t r a t i o n s , both i n t h e room o f o r i g i n and i n o t h e r rooms. I t i s w o r t h s t r e s s i n g t h a t t h e c a l c u l a t i o n s done i n t h i s work h a v e i g n o r e d HC1 d e c a y . T h i s i s very important s i n c e t h e r a t e o f HC1 d e c a y i n s o r p t i v e s u r f a c e s ( s u c h a s concrete or c e i l i n g t i l e ) i s extremely high (half l i v e s of HC1 o f l e s s t h a n 1 min h a v e b e e n c a l c u l a t e d f o r a p l e n u m w i t h such s u r f a c e s [32]). The same c a l c u l a t i o n p r o c e d u r e h a s a l s o b e e n a p p l i e d t o o t h e r p r o d u c t s i n t h e same s c e n a r i o . I n p a r t i c u l a r , i t has been used f o r PTFE w i r e coating i n one of the s c e n a r i o s b e i n g c o n s i d e r e d h e r e [28, 2 9 ] . The results showed t h a t , e v e n i f t h e t o x i c p o t e n c y o f t h e p r o d u c t i n t h e plenum i s e x t r e m e l y h i g h , i t i s e x t r e m e l y u n l i k e l y t o contribute s i g n i f i c a n t l y to f i r e hazard i n the h a b i t a b l e a r e a s i f i t h a s v e r y good f i r e performance. Fire
starting
i n the
Plenum
In t h i s c a s e a c o m p l e t e l y d i f f e r e n t a p p r o a c h was taken. I t was d e c i d e d t o u s e a f i r e m o d e l , o f z o n a l t y p e , t o p r e d i c t smoke f l o w s , t e m p e r a t u r e s and g a s c o n c e n t r a t i o n s . The model c h o s e n f o r t h e s e c a l c u l a t i o n s was t h e NBS Fire and Smoke T r a n s p o r t model ( F . A . S . T . ) , v e r s i o n 18.3 [ 3 3 ] . T h i s model r e q u i r e s t h a t t h e t r a n s p o r t between rooms be i n a h o r i z o n t a l manner. In order t o achieve t h i s , a v i r t u a l room i s n e e d e d and a v e n t i s n e e d e d i n b o t h t h e room and t h e plenum. In order, t h e r e f o r e , t o a n a l y s e a broad v a r i e t y o f d i f f e r e n t f i r e s and s c e n a r i o s , t h e o n l y p r o d u c t u s e d was a low h e a t r e l e a s e w i r e c o a t i n g . The p r o d u c t u s e d f o r t h e s e c a l c u l a t i o n s was a f i r e r e t a r d e d p l a s t i c i z e d PVC w i r e c o a t i n g m a t e r i a l , w h i c h d o e s n o t s p r e a d f l a m e o r c o n t i n u e b u r n i n g u n l e s s an e x t e r n a l source of heat or flame i s d i r e c t e d a t i t . This material was c h o s e n b e c a u s e PVC r e p r e s e n t s t h e most common c a b l e
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
601
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990. 3. 7 3. 7 2. 7
D
5 0
H
o
f
5 0
I f f u e l h a s D e l t a con*> 40 k J / g a n d L C (30 min) Time t o l e t h a l c o n e , ( s ) 224 196 85 73 I f t h e v o l u m e c o n s i d e r e d i n c l u d e s f o u r rooms Time t o l e t h a l c o n e , ( s ) 895 782 339 293
H
Of
of
CT 295 795 0. 86 573 978 1. 40
Alone
GB 295 795 0.89 573 902 1.21
3.7 3.7 2.7
C
i n Room
Fire Fuel
CT 295 795 2.01 573 978 3.27
10.0 10.0 3.0
Β
E f f e c t o f Room
GB 295 795 2. 09 573 902 2. 86
10. 0 10. 0 3. 0
A
Fire
I f f u e l h a s D e l t a con*> Of 20 k J / g a n d L C (30 min) Time t o l e t h a l c o n e , ( s ) 112 98 42 37 I f t h e v o l u m e c o n s i d e r e d i n c l u d e s f o u r rooms Time t o l e t h a l c o n e , ( s ) 448 391 170 147
UL
UL
Susp. c e i l , m a t e r i a l Τ a m b i e n t (K) T a t f l a s h o v e r (K) RHR f l a s h o v e r (MW) Τ plenum (PVC d e c ) (K) T (PVC d e c ) (K) RHR r e q u d (PVC d e c ) (MW)
Room l e n g t h (m) Room w i d t h (m) Room h e i g h t (m)
Scenario
Table I I I .
34 138
160
69
80 40 mg/1 40
17
CT 295 795 0. β: 573 978 1. o;
2. 5 2. 5 2. 5
F
4 0 mg/1 20
GB 295 795 0.64 573 902 0.88
2.5 2.5 2.5
Ε
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Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
5 0
conduit
(100 m; 5 0
5 0
1422
664
mg/L)
1102
(100 m ; L C : 3 2 . 4
1962 1982 644 Time t o l e t h a l c o n e , ( s ) I f t h e v o l u m e c o n s i d e r e d i n c l u d e s f o u r rooms 6675 6695 1402 Time t o l e t h a l c o n e , (s)
PVC ENMT c o n d u i t
mg/L)
584
L C : 37 . 0
564 Time t o l e t h a l c o n e , ( s ) 1465 1485 i n c l u d e s f o u r rooms I f the volume c o n s i d e r e d 1082 Time t o l e t h a l c o n e , (s) 4687 4707
PVC r i g i d
659
mg/L)
3200
(400 m ; L C : 31. 6
639 1928 1948 Time t o l e t h a l c o n e , ( s ) i n c l u d e s f o u r rooms I f t h e volume c o n s i d e r e d 3180 Time t o l e t h a l c o n e , ( s ) 8339 8356
PVC w i r e c o a t i n g
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604
FIRE AND POLYMERS
coating material used overall, although the fire characteristics of the particular example chosen a r e b e t t e r t h a n t h o s e o f t h e a v e r a g e p l a s t i c i z e d PVC. Plenum c a b l e s a r e , o f c o u r s e , v e r y o f t e n a l s o made o f f l u o r i n a t e d materials. A t o t a l o f 400 m o f t h e PVC w i r e were assumed t o be p r e s e n t i n a plenum. C a l c u l a t i o n s were made f o r many f i r e s c e n a r i o s . T h e s e v a r i e d i n f i r e s i z e a n d i n t h e burning c h a r a c t e r i s t i c s of the material burning i n the fire. I n v i e w o f t h e good f i r e p e r f o r m a n c e o f t h e w i r e coating itself, i t was p o s s i b l e t o i g n o r e t h e m i n u t e p r o b a b i l i t y o f i t being t h e item f i r s t i g n i t e d . A f r a c t i o n a l f a c t o r i a l d e s i g n was u s e d t o e x a m i n e t h e effects of 9 variables which were thought t o be significant. The v a r i a b l e s were: • F i r e heat • F i r e heat
release rate o f combustion
A set of five variables relating t o s i z e and o r i e n t a t i o n o f v e n t s c o n n e c t i n g p l e n u m a n d room ( t o p s o f p l e n u m v e n t and plenum a n d o f room v e n t a n d room c o i n c i d e ) • • • • •
Width o f Width o f Location Width o f Location
A set orientation surroundings • Vent • Vent
a d u c t c o n n e c t i n g room a n d p l e n u m v e n t i n plenum o f b o t t o m o f v e n t i n plenum v e n t i n room o f b o t t o m o f v e n t i n room
o f two v a r i a b l e s relating to size of single vent connecting room ( b o t t o m s o f v e n t a n d room c o i n c i d e )
and and
width height
T h r e e f i r e s i z e s were c h o s e n : 50, 275 a n d 500 kW, a n d t h e h e a t s o f c o m b u s t i o n p i c k e d , v i z . 20, 40 a n d 57 k J / g , r e p r e s e n t a s p r e a d between t h e n o r m a l h e a t o f c o m b u s t i o n o f most common m a t e r i a l s (20 kJ/g) a n d t h a t o f methane (57 kJ/g) . T h i s c o v e r s a v e r y wide range o f f i r e s and o f combustible materials s t a r t i n g the f i r e . In o r d e r t o c o v e r t h e s e n i n e v a r i a b l e s a d e q u a t e l y , a s t a t i s t i c a l e x p e r i m e n t a l d e s i g n was c a l c u l a t e d . The s t a t i s t i c a l e x p e r i m e n t a l d e s i g n r e q u i r e s t h e u s e o f 15 simulations f o r each plenum size. Simulations were r e p e a t e d u s i n g 3 and 10 p l e n u m s . The N a t i o n a l B u r e a u o f S t a n d a r d s (NBS, now N a t i o n a l I n s t i t u t e f o r Standards and Technology, NIST) f i r e a n d smoke t r a n s p o r t m o d e l , F.A.S.T., v e r s i o n 18.3, was u s e d t o g e n e r a t e t h e i n f o r m a t i o n c o n c e r n i n g t h e temperatures and gas c o n c e n t r a t i o n s . T h i s i s a zone model w h i c h p r e d i c t s t h e f o r m a t i o n o f two l a y e r s i n e a c h compartment. Once t h e c o n d i t i o n s g e n e r a t e d by e a c h f i r e were known, d e c i s i o n s were t a k e n a s t o w h i c h f i r e s w o u l d c a u s e s i g n i f i c a n t decomposition of these cables. Some e x a m p l e s
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
34.
GALLOWAY & HIRSCHLER
Effect ofPoly (vinyl chloride) Wire Coating
o f s u c h c a s e s were t h e n r u n , where i t was assumed, f o r simplicity, that the PVC generated, initially, only hydrogen chloride (HC1). The r a t e o f HC1 generation i n c o r p o r a t e d i n t o e a c h example was c a l c u l a t e d b a s e d on t h e temperatures a c h i e v e d i n t h e plenum, a s p r e d i c t e d by F.A.S.T. HC1 d e c a y was i g n o r e d , a s a f i r s t a p p r o x i m a t i o n , j u s t a s i t had been i n t h e o t h e r s e t o f c a s e s .
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R e s u l t s And
Discussion of F i n a l
Case
T a b l e s IV-VI p r e s e n t t h e main r e s u l t s c a r r i e d o u t w i t h 1, 3 and 10 p l e n u m s . d i v i d e d i n two c a t e g o r i e s : (i)
(ii)
of the s i m u l a t i o n s Most c a s e s c a n be
the f i r e i s v e r y i n t e n s e but runs out and s e l f - e x t i n g u i s h e s f a i r l y q u i c k l y ;
of
oxygen
the f i r e continues burning f o r a long time, p l e n u m t e m p e r a t u r e s a r e f a i r l y low.
but
A number o f a d d i t i o n a l c a s e s were a l s o t r i e d , i n w h i c h t h e r e was a d i r e c t o p e n i n g between t h e p l e n u m and the surroundings. None o f them p r o d u c e d any s i g n i f i c a n t amount o f smoke f l o w i n g i n t o t h e room: t h e n e t flow t h r o u g h t h e o p e n i n g was a l w a y s o u t w a r d , s o t h a t no a i r e n t e r e d t h e system t o r e p l e n i s h t h e oxygen. These cases are not being r e p o r t e d i n d e t a i l here, i n the i n t e r e s t of s p a c e economy. Only those f i r e s i n category ( i ) cause s u f f i c i e n t l y h i g h plenum t e m p e r a t u r e s t o a l l o w d e c o m p o s i t i o n o f t h e PVC. PVC w i l l s t a r t d e c o m p o s i n g a t c a . 473 K, and w i l l decompose r a p i d l y a t t e m p e r a t u r e s a b o v e 523 Κ o n l y . In a l l t h e c a s e s s t u d i e d w i t h t e n plenums, which represent a heating, v e n t i l a t i n g and a i r conditioning s y s t e m , t h e f i r e was of category ( i i ) . Even i n t h o s e c a s e s were t h e u p p e r l e v e l plenum t e m p e r a t u r e e x c e e d e d 523 K, t h i s n e v e r o c c u r r e d f o r a p e r i o d o f more t h a n 2 min. Virtually a l l the fires resulted in a CO concentration in the room upper level which was s u f f i c i e n t l y h i g h t o cause s e r i o u s concern. However, i n a l l s i n g l e plenum c a s e s , t h e s i z e o f t h e l o w e r l e v e l ( c o l d l a y e r ) i n t h e room and i t s CO c o n c e n t r a t i o n s were s u c h t h a t e s c a p e was v i r t u a l l y a l w a y s p o s s i b l e . A t o t a l o f c a . 60 s i m u l a t i o n s were r u n and i n t h e vast majority of them PVC decomposition plays a negligible, i f any, role. I n o n l y two o f t h e single plenum s i m u l a t i o n s was there a high enough plenum temperature f o r PVC d e c o m p o s i t i o n t o t a k e p l a c e o v e r a p e r i o d o f more t h a n 1 min. T h o s e w o r s t c a s e s , v i z . # 2, and # 13, were a n a l y s e d f u r t h e r , by c o n s i d e r i n g v a r i o u s r a t e s o f PVC d e c o m p o s i t i o n (HC1 g e n e r a t i o n ) , d e p e n d i n g on upper l e v e l temperatures.
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
605
606
FIRE AND POLYMERS T a b l e IV.
Sim.
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# 1 (1) 2 (1) 3 (1) 4 (2) 5 (1) 6 (1) 7 (1) 8 (1) 9 (2) 10 (2) 11 (2) 12 (1) 13 (1) 14 (2) 15 (2)
Simulations with a single
Timel >473K min
Time2 >523K min
1
0
plenum
D e p t h maxRm CO maxRm Τ max i n room ppm Κ m 1.7
(11)11,280
(11)
33 8
2
1 (614)
1.8
(11)
4,987
(11)
33 4
1
1 (621)
1.1
(11)
6,150
(11)
34 6
0.9
( 6)12,150 ( 8) 3 0 1
0
0
1
1 (618)
1.1
(10)
6, 121 (11)
34 1
1
1 (622)
1.2
( 9)10,960 (11)
34 4
1
1 (618)
1.2
(11)
2,297
(11)
34 2
1
1 (573)
1.3
(10)
4,808
(11)
34 9
0
0
0.9
( 7) 1,849
( 9) 3 0 3
0
0
1.8
(11)
5,724
( 8) 3 0 0
0
0
1.2
(8) 1,837
( 9) 3 0 4
1
1 (630)
1.6
(11)
6,983
(11)
34 6
2
1 (563)
1.9
(11)
4, 101 (11)
33 5
0
0
1.0
( 7) 1,122
( 9) 3 0 3
0
0
1.4
(10)
3,846
( 8) 3 0 3
Legends: T i m e l : p e r i o d u p p e r l e v e l plenum temperature e x c e e d s 473 K; Time2 : idem f o r 523 Κ (maximum, i n K) ; D e p t h max: maximum smoke l a y e r d e p t h ( t i m e r e a c h e d , i n min) ; Rm CO max: maximum room u p p e r l e v e l [CO] ( t i m e r e a c h e d , i n min) ; Rm Τ max: maximum room u p p e r level temperature (time reached, i n min).
The d e h y d r o c h l o r i n a t i o n r a t e s o f PVC c o n s i d e r e d were [3, 2 9 ] : (a) f o r t h e r a n g e (b) f o r t h e r a n g e (c) f o r t h e r a n g e
473 - 523 K: 0.3 %/min 523 - 563 K: 1.0 %/min above 563 K: 2.3 %/min
Furthermore, f o r lower l e v e l temperatures w e l l below mininum PVC d e c o m p o s i t i o n t e m p e r a t u r e , i t was assumed t h a t no more t h a n 20 % o f t h e c a b l e l e n g t h , v i z . 80 m, was
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
34.
T a b l e V. Sim.
#
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Effect ofPolyvinyl chloride) Wire Coating
GALLOWAY & HIRSCHLER
1 (1) 2 (1) 3 (1) 4 (2) 5 (1) 6 (1) 7 (1) 8 (1) 9 (2) 10 (2) 11 (2) 12 (1) 13 (1) 14 (2) 15 (2)
Timel >473K min
S i m u l a t i o n s w i t h t h r e e plenums Time2 >523K min
D e p t h maxRm CO maxRm Τ max i n room ppm m Κ
2
2 (541)
1.6
( 2)15,470
(11)
36 4
2
1 (614)
1.8
(11)
4,987
(11)
33 4
1
1 (621)
1.1
(11)
6,150
(11)
3 46
0.9
( 6)12,150
0
0
( 8) 3 0 1
1
1 (618)
1.1
(10)
6,121
(11)
341
1
1 (622)
1.2
( 9)10,960
(11)
34 4
1
1 (618)
1.2
(11)
2,297
(11)
34 2
1
1 (573)
1.3
(10)
4,808
(11)
34 9
0
0
0.9
( 7) 1,849
( 9) 3 0 3
0
0
1.8
(11)
5,724
( 8) 3 0 0
0
0
1.2
(8)
1,837
( 9) 3 0 4
1
1 (630)
1.6
(11)
6,983
(11)
3 46
2
1 (563)
1.9
(11)
4,101
(11)
33 5
0
0
1.0
( 7) 1,122
( 9) 3 0 3
0
0
1.4
(10)
3,846
( 8) 3 0 3
Legends as i n T a b l e IV. decomposed s i m u l t a n e o u s l y . The l i n e a r d e n s i t y o f c a b l e c o a t i n g u s e d i s 70 g/m. In both of these s i m u l a t i o n s , w o r s t c a s e s c e n a r i o s , ( T a b l e V I I ) i t i s c l e a r t h a t t h e HC1 c o n c e n t r a t i o n d o e s n o t i n t r o d u c e much a d d i t i o n a l h a z a r d t o t h a t due t o t h e f i r e i t s e l f , s i n c e t h e l e t h a l p o t e n c i e s o f HC1 a n d o f CO a r e v e r y s i m i l a r [ 1 , 11, 13, 34, 3 5 ] . An investigation of those cases, among the 3 plenum s i m u l a t i o n s , w i t h t h e h i g h e s t p o t e n t i a l f o r e f f e c t s b y PVC y i e l d s t h e same i m p l i c a t i o n s . The main reason for this i s that the products c o n c e r n e d h a v e good f i r e p e r f o r m a n c e . T h e y h a v e v e r y low h e a t r e l e a s e c h a r a c t e r i s t i c s , s o t h a t t h e y do n o t a d d s i g n i f i c a n t l y t o t h e energy o f t h e f i r e and, f u r t h e r m o r e , w i l l n o t s p r e a d f l a m e i n t h e a b s e n c e o f an e x t e r n a l e n e r g y source, so t h a t they h a r d l y i n c r e a s e t h e f u e l supply f o r the f i r e .
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
607
608
FIRE AND POLYMERS
Sim.
# —
Table VI.
Simulations with
Timel >473K min
Time2 >523K min
t e n plenums
D e p t h maxRm CO maxRm Τ max i n room
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m 1 (4) 2 (1) 3 (1) 4 (2) 5 (1) 6 (1) 7 (1) 8 (1) 9 (2) 10 (2) 11 (2) 12 (1) 13 (1) 14 (2) 15 (2)
Κ
ppm
0
0
2.1
( 4)15,050
( 8) 3 3 6
0
0
1.8
(11) 4,987
(11)
33 4
0
0
1.1
(11) 6, 150 (11)
34 6
0
0
0.9
( 6)12,150
( 8) 3 0 1
0
0
1.1
(10) 6,121
(11)
34 1
0
0
1.2
( 9)10,960
(11)
34 4
0
0
1.2
(11) 2,297
(11)
34 2
0
0
1.3
(10) 4,808
(11)
34 9
0
0
0.9
( 7) 1,849
( 9) 3 0 3
0
0
1.8
(11) 5,724
( 8) 3 0 0
0
0
1.2
1,837
( 9) 3 0 4
0
0
1.6
(11) 6,983
(11)
34 6
0
0
1.9
(11) 4,101
(11)
33 5
0
0
1.0
( 7 ) 1, 122 ( 9 ) 3 0 3
0
0
1.4
(10) 3,846
(8)
( 8) 3 0 3
Legends as i n T a b l e IV. Table VII. Simulation
#
R e s u l t s o f Some S i m u l a t i o n s w i t h PVC T/2 Γ7Ϊ3 372 Room Upper L a y e r R e s u l t s
CO § 2 m i n (ppm) 4 , 325 HC1 @ 2 m i n (ppm) 20 CO @ 5 m i n (ppm) 4 , 325 HC1 @ 5 m i n (ppm) 20 CO @ 10 m i n (ppm) 4 ,564 HC1 § 10 m i n (ppm) 202 Max Temp (K) 335 Max Smoke l a y e r (m)
3,13
1, 221 0 1, 593 108 3, 828 668 335 1.8
3, 314 0 5, 204 112 5, 204 112 327 1.9
2 , 957 93 3, 156 126 5, 282 696 353 2.0
562
497
583
9 9
Max P l e n Temp (K)
615
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
34.
GALLOWAY & HIRSCHLER
Effect ofPoly(vinyl chloride) Wire Coating
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Conclusions F i r e s s t a r t i n g i n a room may e v e n t u a l l y g e t t r a n s f e r r e d t o a p l e n u m a b o v e i t . However, by t h e t i m e t h e e f f e c t s o f such a fire cause PVC products (rigid c o n d u i t , ENMT c o n d u i t and w i r e c o a t i n g ) i n t h e plenum t o b u r n , t h e room has a l r e a d y r e a c h e d f l a s h o v e r c o n d i t i o n s . Furthermore, t h e smoke g e n e r a t e d by t h e room f i r e f u e l c a u s e s much f a s t e r t o x i c c o n c e r n t h a n t h a t f r o m t h e PVC p r o d u c t s i n t h e plenum. Fires starting i n a plenum communicated to the o u t s i d e are u n l i k e l y t o cause concern i n h a b i t a b l e areas. If the plenum i s isolated from the o u t s i d e , a fire starting i n i t i s more l i k e l y t o cause a hazardous s i t u a t i o n i n t h e room b e l o w i f t h e p l e n u m i s c o m m u n i c a t e d w i t h o t h e r plenums. The u s e o f f i r e s a f e PVC w i r e c o a t i n g p r o d u c t s i n a plenum, d i d n o t c o n t r i b u t e , in virtually any of the s i m u l a t i o n s r e p o r t e d here, to a s i g n i f i c a n t i n c r e a s e i n t h e f i r e h a z a r d due t o t h e f i r e i t s e l f . This conclusion i s v a l i d b o t h f o r t h e c a s e s where t h e f i r e s t a r t s i n t h e room and f o r t h e c a s e s where t h e f i r e starts i n the plenum.
References 1. 2. 3. 4. 5.
6. 7.
8.
H i r s c h l e r , M.M. General P r i n c i p l e s of F i r e Hazard and the Role of Smoke T o x i c i t y , T h i s volume. C u l l i s , C.F. and H i r s c h l e r , M.M. The Combustion of Organic Polymers, Oxford U n i v e r s i t y Press, Oxford, 1981. H i r s c h l e r , M.M., Europ. Polvmer J., 22, 153 (1986). H i r s c h l e r , M.M., F i r e Prev. 204, November, p. 19 (1987). Smith, Ε.Ε.,in Ignition, Heat Release and Non-combustibility of M a t e r i a l s , A.S.T.M. STP 502 (Ed. A.F. Robertson), p.119, Amer. Soc. T e s t i n g Mater., P h i l a d e l p h i a , PA (1972). H i l a d o , C.J., Flammability Handbook f o r P l a s t i c s . 3rd.Edn, Technomic, Lancaster, 1982. H i r s c h l e r , M.M. and Smith, G.F. Determination of F i r e P r o p e r t i e s of Products by Rate of Heat Release C a l o r i m e t r y : Use of the N a t i o n a l Bureau of Standards Cone and Ohio State U n i v e r s i t y Instruments, i n Proc. F i r e Retardant Chemicals Assoc. Fall 1987 Conf., F i r e Safety Progress i n Regulations, Technology and New Products, Monterey, CA, Oct. 18-21, p.133 (1987). H i r s c h l e r , M.M. and Smith, G.F., Eastern States Comb. I n s t . F a l l Tech. Mtg, Nov. 2-6, 1987, pap. 63, Gaithersburg, MD, Combustion I n s t i t u t e , P i t t s b u r g h , PA (1987).
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
609
610 9.
Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on April 1, 2018 | https://pubs.acs.org Publication Date: May 9, 1990 | doi: 10.1021/bk-1990-0425.ch034
10.
11. 12. 13. 14. 15. 16.
17. 18. 19. 20. 21.
22.
23. 24.
25.
26.
FIRE AND POLYMERS
Hirschler, M.M., 31st. IUPAC Microsymp. on Macromolecules P o l y ( V i n y l Chloride), Prague, 18-21 J u l y (1988), Makromol. Chem., Macromol. Svmp. 29, 133-53 (1989). Levin, B.C., Fowell, A.J., B i r k y , M.M., Paabo, Μ., S t o l t e , A. and Malek, D., Further Development of a Test Method f o r the Assessment of the Acute I n h a l a t i o n T o x i c i t y of Combustion Products, Nat. Bur. Stands., Gaithersburg, MD, NBSIR 82-2532 (1982). H i r s c h l e r , M.M., J . F i r e S c i . 5, 289 (1987). Kaplan, H.L., Grand, A.F., Switzer, W.G., Mitchell, D.S., Rogers, W.R. and H a r t z e l l , G.E., J . F i r e S c i . 3, 228 (1985). Hinderer, R.K. and Hirschler, M.M. J. Vinyl Technology, 11(2), 50 (1989). Higgins, E.A., Diorca, V., Thomas, A,A. and Davis, H.V., F i r e Technol. 8, 120 (1972). Darmer, K.I., Kinkead, E.R. and DiPasquale, L.C., Am. Ind. Hvg. Assoc. J . 35, 623 (1974). Kaplan H.L., H i r s c h l e r , M.M., Switzer, W.G. and Coaker, A.W., Proc. 13th. I n t . Conf. F i r e Safety (Ed. C.J. H i l a d o ) , p. 279, Product Safety, San F r a n c i s c o , CA (1988). Hartzell, G.E., Packham, S.C., Grand, A.F. and Switzer, W.G., J . F i r e S c i . 3, 195 (1985). Hinderer, R.K. and Kaplan, H.L., Dangerous P r o p e r t i e s of I n d u s t r i a l M a t e r i a l s Report, p. 2, Mar-Apr (1987). A l a r i e , Y.R., Ann. Rev. Pharmacol. T o x i c o l . 25, 325 (1985). B e i t e l , J . J . , B e r t e l o , CA., C a r r o l l , W.A., Gardner, R.A., Grand, A.F., H i r s c h l e r , M.M. and Smith, G.F., J . F i r e S c i . 4, 15 (1986). B e r t e l o , C.A., C a r r o l l , W.F., H i r s c h l e r , M.M. and Smith, G.F., Proc. 11th. I n t . Conf. F i r e Safety (Ed. C.J. H i l a d o ) , p. 192, Product Safety, San F r a n c i s c o , CA (1986). B e r t e l o , C.A., C a r r o l l , W.F., H i r s c h l e r , M.M. and Smith, G.F., F i r e Safety Science, Proc. 1st. I n t . Svmp. (Ed. C.E. Grant and P.J. Pagni), p. 1079, Hemisphere, Washington (1986). B e i t e l , J . J . , B e r t e l o , C.A., C a r r o l l , W.A., Grand, A.F., H i r s c h l e r , M.M. and Smith, G.F., J . F i r e S c i . 5. 105 (1987). Galloway, F.M. and H i r s c h l e r , M.M., Mathematical Modeling of F i r e s , A.S.T.M. STP 983 (Ed. J.R. Mehaffey), p. 35, Amer. Soc. T e s t i n g . Mater., P h i l a d e l p h i a , PA (1987). Burgess, W.A., Treitman, R.D. and Gold, Α., Air Contaminants i n S t r u c t u r a l F i r e f i g h t i n g . N.F.P.C.A. P r o j e c t 7X008, Harvard School P u b l i c Health, Cambridge, MA (1979). Grand, A.F., Kaplan, H.L. and Lee, G.H.. I n v e s t i g a t i o n of Combustion Atmospheres i n Real F i r e s , U.S.F.A. Project 80027, Southwest Research Institute, San Antonio, TX (1981).
Nelson; Fire and Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 1990.
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34.
GALLOWAY & HIRSCHLER
Effect ofPoly(vinyl chloride) Wire Coating
27. New York State Uniform Fire Prevention and Building Code - Art. 15, Part 1120 Combustion Toxicity Testing and Regulations for Implementing Building Materials and Finishes. Fire Gas Toxicity Data F i l e , Albany , NY (1987). 28. Bukowski, R.W., Fire Technol. 21, 252 (1985). 29. Hirschler, M.M., J. Fire Sci. 6, 100 (1988). 30. Benjamin, I.Α., J . Fire Sci. 5, 25 (1987). 31. McCaffrey, B.J., Quintiere, J.G. and Harkleroad, M.F., Fire Technol. 17, 98 (1981). 32. Galloway, F.M. and Hirschler, M.M. Fire Safety J. 14, 251 (1989). 33. Jones, W.W., A Model for the Transport of Fire, Smoke and Toxic Gases (FAST). NBSIR 84-2934, Natl Bur. Stands., Gaithersburg, MD (1984). 34. Babrauskas, V., Levin, B.C. and Gann, R.G., Fire Journal. 81(2), 22 (1987). 35. Hartzell, G.E., Packham, S.C., Grand, A.F. and Switzer, W.G., J . Fire Sci. 3, 195 (1985). RECEIVED
November 1, 1989
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