Small-scale fire test of 6 inch wall penetrated by telephone cables

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Small-scale fire test of 6 inch wall penetrated by telephone cables

McGuire, J. H.

SMALL-SCALE FIRE

TEST

BY TELEPHONE CABLES

J . H . McGuire

A p o s i t i v e pressure f i r e test w a s carried o u t on t w o small- scale 6 i n . thick, high-temperature concrete w a l l s penetrated by

13

bulk Eihrc,

with

constituted the firestopping a r o u n d the cables. The penetrations proved s a t i s f a c t o r y except f o r those i n v o l v i n g the t w o largest

c a b l e s , which gave u n a c c e p t a b l y h i g h temperatures after approximately 2 hr of test. Sealing t h e ends of the cables could have further

improved performance.

The test r e p o r t e d in t h i s n o t e w a s carried o u t at the request of E e l 1 Canada to supplement tnformation gained from a series of

similar tests, conducted in

1974,

Canada. The object of t h e t e s t was to determine whether penetrations

by selected telephone cables would i m p a i r t h e fire containment

i n t e g r i t y of a high-temperature concrete w a l l 6 in. t h i c k , for a

period of 2 hr. F a i l u r e c r i t e r i a were as follows: temperatures exceeding

1000"~

openings greater than 0.1 s q tn- (65 mm2).

TEST SPECIMENS

The t w o walls, one i n s t a l l e d at each e n d of the f u r n a c e c o n s i s t e d of high-temperature concrete, 16 in. square by 6 in. thick

(406 mm x 152 m ) , of d e n s i t y apprnxTmate1y 60 l b f c u f t: (961 kg/m3]. Figures 1 and 2 i l l u s t r a t e the specimen walls (after test), penetrated

by t h e cables s p e c i f i e d in Table 1. P i r e s t o p p i n g was by alumina-

silica-ceramic bulk f i b r e and one of t h r e e c e m e n t i t i o u s sealants. The

c a b l e s were separated from each other by at least 3 / 4 in. (19 mm). The

f i b r e p a c k i t ~ g was i n s e r t e d from the exterior (unexposed) face of

t h e wall and was allowed to protrude a l i t t l e beyond the i n s i d e face.

P a c k i n g w a s c o n t i n u e d u n t i l the f i b r e wool extended to within an

inch of t h e exterior Face. The cementitious s e a l a n t s listed in Table

2 were t h e n used to cap t h e o p e n i n g s . There were no cables a s s o c i a t e d

with o p e n i n ~ s F, M and J -

S m a l l amounts of a p l i a b l e p l a s t i c s e a l a n t w e r e a p p l i e d a t

t w o l o c a t i o n s on t h e e x t e r i o r face of opening

G

In previous t e s t s t h e unexposed ends of the cables were

capped to prevent the flaw of h a t gases through t h e cables when t e s t i n g under positive pressure. A s shown in Figures 1 and 2, this procedure

TEST PROCEDURE AND

RESULTS

The furnace was operated

for

over

temperatures following the

ULC

of 5 rnm

WG

was maintained (to within

10%)

F i g u r e 3. Adopting t h e f a i l u r e c r i t e r i o n of l000"~ { 5 3 ~ . 8 ~ ~ ) at t h e unexposed surfaces of a c a b l e , penetrations G5 and 6 7 f a i l e d at approximately 119 rnin and 1 2 2 m i n respectively. Rased on t h e excessive opening criterion, G5 was t h e only p e n e t r a t i o n n o t meeting the

requirement; f a i l u r e occurred at 118 m i n .

Toward the end of t h e t e s t , hot gases were seen to be issuing from the end of cable G 5 , _{between the wires} and the metal sheath.

Very high temperatures had developed resulting in the d e s t r u c t i o n of the insulation of most of t h e i n d i v i d u a l p a i r s . Subsequent examination

of cables B and D, which were of a similar type, showed that they had exhibited the same behaviour to a lesser exrenr.

The

beneath D at 53 min and t h e blister punctured 2 m i n l a t e r . A t

72 min, G5 d e v e l o p e d a s m a l l b l i s t e r Ehat was d r i p p i n g at

91

Over t h e same period, a b l i s t e r had also d e v e l o p e d beneath c a b l e B. R a p i d development of a blister beneath

G 4

Some time a € ter t h e t e s t , thr c o n d i t i o n of the three capping

materials was examined. The F l i n t k o t e " t o p 'n bondt'appeared

substantially unaffected by the exposure and, to n lesser e x t e n t , the same was true o f the "Water S e a l " q u i c k - s e t cement. Although r e t a i n t n g reasonable s t r e n g t h , the vermiculite/sand/cement mixture had shrunk, however, and had Left a crack at t h e perimeter of each

penetration.

CQNCLUS IONS

The f i r e containment performance of 6 in. concrete wall

s p e c i m e n s , i n c l u d i n g penetrations by various t e l e p h o n e cables

r a n g i n g in diameter up to 3 in. (76 mm), remained satisfactory f o r

almost 2 hr when exposcd in a Eurnace o p e r a t i n g at positive pressure.

Firestnppin~ i n v o l v e d alumina-silicate-ceramic b u l k f i b r e and

1

cementltious capping. An experimental vermiculite/sand/cment capping was f o u n d to behave more poorly than t w o proprietary mixes.

Acknowledjieinent i s d u e t o Mcssrs. R . G . Cotton and R. D.

P a r k c r of IkI1 Canada for the p r a v i s i n n of t h e cables and f o r much

of t h e p l a n n i n g of thc! t e s t and to Mcssts.

P.

DRR

TABLE 2

CEMENTITIOUS CAPPING

I<, K , G , ,J

J

Port 1 ;and ccmcn t ( 3 : 1 : 1)

----

C A B L E NUMBERING K E Y

FIGURE

1

U N E X P O S E D F A C E

OF W A L L S P E C I M E N N O .

J H

C A B L E NUMBERING K E Y

FIGURE

2

U N E X P O S E D

F A C E

W A L L

N O .

A F T E R