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Fire and leakage tests of dampers for smoke shafts

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NATIONAL RESEARCH COUNCIL OF CANADA DlVlSlClN OF BUILDING RESEARCH

DBR INTERNAL REPORT NO. 428

FIRE AND LEAKAGE TESTS OF DAMPERS FOR SMOKE SHAFTS

by J . H . McGUIRE and G.T. TAMURA

Checked by: G . W . S. Approved by: C

.

B . C

.

Date: April 1976

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PREFACE

With the recognition of the potential magnitude of smoke

problems in high buildings, various smoke control measures have

been developed. Some of these depend on smoke shafts intended to

serve any one of a number of storeys.

A

need has thus arisen for

a type of damper that must meet more rigorous requirements than

are intended for a duct application. This report describes fire

tests on prevailing designs that might be considered for smoke

shaft application. In general performance was fair from the

point of view of leakage but poor from the thermal point of view

in that high temperatures (650 to 850°C) developed at the

unexposed surfaces.

Ottawa

April 1976

C

.

B. Craw

ford

Director, DBR/NRC

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FIRE AND LEAKAGE TESTS OF DAMPERS FOR SMOKE SHAFTS by

.J. 11. McGuire and G.T. Tamura

INTRODUCTION

I n r e c e n t y e a r s , a t t e n t i o n h a s been f o c u s s e d on smoke

problems i n h i g h b u i l d i n g s . S e v e r a l approaches a r e p o s s i b l e and some i n v o l v e t h e u s e o f smoke s h a f t s i n t e n d e d t o withdraw g a s e s from t h e f i r e a r e a i n o r d e r t o r e d u c e t h e p r e s s u r e i n t h e a r e a . O c c a s i o n a l l y t h e u l t i m a t e o b j e c t i v e i s t o c r e a t e a s t e a d y - s t a t e n e g a t i v e p r e s s u r e d i f f e r e n t i a l a c r o s s a l l p a r t i t i o n s s e p a r a t i n g t h e f i r e compartment from a d j a c e n t p a r t s o f t h e b u i l d i n g . T h i s i s a c h i e v e d by s t a c k a c t i o n i n t h e smoke s h a f t o r by means o f a n e x h a u s t f a n a t t h e t o p o f t h e s h a f t . More f r e q u e n t l y t h e aim i s merely t o a v o i d p r e s s u r e b u i l d - u p i n t h e f i r e r e g i o n , which r e s u l t s from t e m p e r a t u r e r i s e , by p e r m i t t i n g t h e expanding atmosphere t o v e n t by way o f t h e smoke s h a f t .

To c r e a t e e i t h e r o f t h e s e c o n d i t i o n s a s u b s t a n t i a l s i z e o f s h a f t i s o f t e n n e c e s s a r y and, f o l l o w i n g t h e o u t b r e a k o f a f i r e , openings a r e made a t t h e t o p o f t h e s h a f t and t o t h e f i r e r e g i o n .

A v e r y t i g h t c l o s u r e must be m a i n t a i n e d a t a l l o t h e r f l o o r s s e r v e d by t h e smoke s h a f t b e c a u s e i t s e f f e c t i v e n e s s i s g r e a t l y i m p a i r e d i f t h e t o t a l l e a k a g e t o t h e s h a f t from t h e s e o t h e r f l o o r s becomes comparable w i t h t h e flow from t h e f i r e r e g i o n . Thus i f f i f t y f l o o r s were s e r v e d , t h e e f f e c t i v e l e a k a g e a r e a o f e a c h damper, n e g l e c t i n g t h e magnitude o f t h e s h a f t w a l l l e a k a g e , s h o u l d n o t exceed 2 p e r c e n t o f t h e f r e e a r e a g i v e n when t h e damper i s open. I n f a c t , s h a f t w a l l and damper l e a k a g e s a r e o f t e n o f t h e same o r d e r o f magnitude, making t h e damper l e a k a g e r c q u i r e m c n t s more s t r i n g e n t . Damper l e a k a g e r e q u i r e m e n t s a r e ~ ) ; ~ r t i c u l a r l y s c v c r c b c c a u s e t h e r e i s a s t r o n g p o s s i b i l i t y o f f i r e

i n t h c s h a f t and dampers may be exposed t o v e r y h i g h temperatures. r l ~ c r c i s s c r i o u s r i s k o f i g n i t i o n o f c o m b u s t i b l e s by h c a t t r a n s f e r from a damper bccause o f f i r e i n a s h a f t . U n f o r t u n a t e l y , dampers s p e c i f i c a l l y i n t e n d e d f o r smoke s h a f t a p p l i c a t i o n s have n o t y e t been developed and c u r r e n t l y d e s i g n e r s a r e c o n s i d e r i n g u s i n g f i r e dampers complying w i t h ULC S112. These a r e i n t e n d e d t o s e r v e a s f i r e c u t - o f f s i n a i r - h a n d l i n g d u c t s . As s u c h , t h e y a r e n o t e x p e c t e d t o be p a r t i c u l a r l y t i g h t and no unexposed s u r f a c e t e m p e r a t u r e l i m i t i s s p e c i f i e d . The t e s t s d e s c r i b e d i n t h i s

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r e p o r t were c a r r i e d o u t t o a s s e s s t h e s u i t a b i l i t y o f s u c h dampers f o r smoke s h a f t a p p l i c a t i o n s .

T e s t Dampers

Two e a c h o f n i n e d i f f e r e n t models o f damper were p u r c h a s e d a n d , a s l i s t e d i n T a b l e 1 , t h r e e o f t h e d e s i g n s were o f t h e c u r t a i n t y p c , two were s i n g l e - b l a d e and f o u r were m u l t i - b l a d e . A11 werc IJLC a p p r o v c d , complying w i t h LILC S112, S t a n d a r d f o r F i r e Llampcrs.

P r i o r t o t e s t , v e r t i c a l and h o r i z o n t a l t h r o u g h o p e n i n g s , d e f i n e d i n ULC S112 a s "a v i s i b l e o p e n i n g i n t h e f a c e o f t h e damper when viewed on a p l a n e p e r p e n d i c u l a r t o t h e mounting p l a n e 1 ' , were measured on a l l dampers. I t was found t h a t t h e r e were no h o r i z o n t a l t h r o u g h o p e n i n g s b e c a u s e c o n s t r u c t i o n i n v o l v e d i n t e r l o c k i n g b l a d e s . V e r t i c a l t h r o u g h o p e n i n g s o f a l l c u r t a i n t y p e dampers were a l s o n o n - e x i s t e n t b u t t h o s e o f t h e b l a d e t y p e dampers v a r i e d from 0 t o 0.32 i n . These t h r o u g h c l e a r a n c e s complied w i t h ULC S112, b e i n g less t h a n t h e maximum 1/32 i n . f o r h o r i z o n t a l t h r o u g h o p e n i n g s and 3 / 8 i n . f o r v e r t i c a l t h r o u g h o p e n i n g s .

FIRE TESTS AND OBSERVATIONS

A t o t a l o f s i x 2 - h r f i r e tests were c a r r i e d o u t w i t h t h e l a r g e NRC w a l l f u r n a c e , each i n v o l v i n g between t h r e e and f i v e dampers. S e v e r a l d i f f e r e n t modes o f f u r n a c e o p e r a t i o n were a d o p t e d .

F i r s t T e s t

The f i r s t t e s t was b a s i c a l l y c a r r i e d o u t t o IJLC S112

s p e c i f i c a t i o n s b u t b a r e uncapped f u r n a c e t h e r m o c o u p l e s were u s e d t o r e g i s t e r t h e f u r n a c e t e m p e r a t u r e . A s a r e s u l t , t h e t e s t

dampers were n o t exposed t o a s s e v e r e a t h e r m a l shock a s h a s been customary w i t h t h e NRC f u r n a c e s , which h i t h e r t o have u t i l i s e d heavy b l a c k i r o n p i p e a s a c a p p i n g m a t e r i a l .

Although i t i s n o t s p e c i f i e d i n S112, f u r n a c e p r e s s u r e ( p o s i t i v e o r n e g a t i v e ) c o u l d be a s i g n i f i c a n t f a c t o r g o v e r n i n g performance o f t h e dampers. The f i r s t t e s t was c a r r i e d o u t u n d e r t h c c o n d i t i o n i n which t h e f u r n a c e was u n d e r n e g a t i v e p r e s s u r e . Smoke s h a f t s a r e i n t e n d e d t o o p e r a t e u n d e r s u c h a c o n d i t i o n . A t a b o u t m i d - h c i g h t o f t h e dampers, t h e p r e s s u r e d i f f e r e n t i a l

hctwccn i n t c r i o r and c x p c r i o r was - 1 . 6 mm (-0.06 i n . ) W.G. (Water Gauge). A t a h i g h t e m p e r a t u r e , t h e i n t e r i o r - e x t e r i o r p r e s s u r e d i f f c r c n t i a l changes by up t o 0 . 8 mm W.G. p e r m e t r e change i n h e i g h t ( 0 . 0 1 i n . W.G. p e r f o o t ) from any r e f e r e n c e I c v e l , t h e i n t c r i o r p r c s s u r c b e i n g t h e g r e a t e r a t h i g h e r l e v e l s . T h i s s h a r p

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variation of pressure differential with height was, in fact, the fcaturc that limited the number of dampers installed in any one test wall.

The dampers installed in the first wall were Nos. 302779, 320948 and 333307. All were of curtain design. Figure 1 shows thesc dampers at the close of thc test, mounted in a concrete block wall. 'The brickwork was included to achieve suitable scparation of the dampers and to serve as columns supporting the load of the sills above the dampers. These mounting arrangements were used in all subsequent tests.

Figure 1 shows that the 2-hr fire exposure did not do great physical damage to the dampers. Following slight warping in the first 5 min of test, the various parts of the dampers then

maintained their positions and integrity throughout the 2-hr test period. The only event of any significance occurred a few

minutcs after the furnace had been shut down, when one of the rivcts securing the top of the central damper (No. 320948) failed Figure lb illustrates the resulting collapse on one side of the assembly.

Figure 2 is a record of the temperature of one of the dampers (No. 302779) showing that very high temperatures prevailed within

a few minutes of the start of the test. Unless, in practice, all combustible materials were kept well away from the damper and it was completely open to a large atmosphere to permit free cooling, risk of ignition would be substantial.

Second Test

The second test was intended to be a repeat of the first but with the furnace under positive pressure. Replicate dampers were used, with serial Nos. 295595, 322318 and 333408. The pressure was to be maintained (at about mid-height of the dampers) at +5.1 mrn (0.2 in.)

W.G.

but for the first 8 min it was slightly lower (-4 mm; -.16 in.). Subsequently it was maintained to within 10 pcr ccnt of the required level.

7'hc hchaviour of the dampers as indicated by the test notes w;~s virtu:llly thc snmc as in thc first test even to failure of

one or the rivcts of thc middle damper (No. 322318) immediately following thc end of the test.

Figure 3, which corresponds to Figure 2 relating to thc first

tcst, shows an anomaly, however; the temperatures shown in Figurc 3 would be expected to be higher than those of Figurc 2 hecause of the positive pressure condition. They were in fact

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t e c h n i q u e o f f i x i n g t h e thermocouples t o t h e dampers. The ends were t w i s t e d and had f i n i t e l e n g t h , and d i f f i c u l t y was e x p e r i e n c e d i n e n s u r i n g c l o s e c o n t a c t between t h e damper and t h e w i r e s o v e r t h e l e n g t h i n which t h e two w i r e s were i n e l e c t r i c a l c o n t a c t . Temperature r e c o r d s ( n o t i n c l u d e d i n t h i s r e p o r t ) o f o t h e r thermocouples a f f i x e d t o t h e dampers d i d n o t g e n e r a l l y show t h e same nnoma 1 y

.

Thc c o n c l u s i o n t o be drawn from t h e t e m p e r a t u r e r e c o r d s o f t h c sccnnd t e s t i s t h e same a s t h a t g i v e n by t h e g e n e r a l o h s c r v n t i o n s ; v i z . , t h a t o p e r a t i n g t h e f u r n a c e a t p o s i t i v e p r c s s u r c o v c r 2 - h r p c r i o d does n o t a p p r e c i a b l y i m p a i r damper ( t c m p c r a t u r e ) pcrforrnance as compared t o n e g a t i v c p r e s s u r e o p e r a t i o n . T h i r d T e s t The o b j e c t o f t h e t h i r d t e s t was t o d e t e r m i n e t h e i n f l u e n c e , on damper performance, o f t h e u s e of t h e e x c e s s i v e l y t h i c k c a p s on t h e f u r n a c e thermocouples c u s t o m a r i l y used a t t h e NRC f a c i l i t y A s d i s c u s s e d e a r l i e r , t h e thermocouples c o n s t i t u t e t h e f u r n a c e - c o n t r o l s e n s i n g e l e m e n t s . I n c r e a s i n g t h e t h e r m a l l a g o f t h e c o u p l c s c a u s e s t h e c o n t r o l l e r t o r a i s e t h e f u r n a c e t e m p e r a t u r e more r a p i d l y , t h u s e x p o s i n g specimens t o g r e a t e r t h e r m a l shock.

Because t h e f i r s t two t e s t s had n o t s e r i o u s l y damaged t h e dampers i n v o l v e d , and i n view o f t h e l a c k o f a t h i r d s e t o f i d e n t i c a l dampers, t h e t e s t was c a r r i e d o u t on t h e s e t used f o r t h e f i r s t t e s t . The r i v e t t h a t had f a i l e d on t h e middle damper was r e p l a c e d by a b o l t . The t e s t was c a r r i e d o u t a t a p o s i t i v e p r e s s u r e o f 5 . 1 mm i-10 p e r c e n t ( 0 . 2 i n . ) W.G. and, a s mcntioned, t h e f u r n a c e thermocouples were capped (13/16 i n . wrought i r o n g a s p i p e c a p s )

.

F i g u r e 4 i s a r e c o r d o f t h e t i m e - t e m p e r a t u r e c u r v e a t t h e l o c a t i o n a d o p t e d d u r i n g t e s t s 2 and 3 . I t can b e s e e n t h a t t h e f u r n a c e thermocouple c a p p i n g r e s u l t e d i n a s l i g h t l y f a s t e r i n i t i a l t e m p e r a t u r e r i s e f o l l o w e d by s u b s t a n t i a l f l u c t u a t i o n a s s o c i a t e d w i t h improper f u r n a c e c o n t r o l . The p h y s i c a l e f f e c t o f g r e a t e r

thermal shock on t h e dampers was, however, minimal and t h e a p p e a r a n c e o f t h e dampers a t t h e c l o s e o f t h e t e s t was o n l y s l i g h t l y d i f f e r e n t from t h e i r a p p e a r a n c e a t t h e b e g i n n i n g . F o u r t h T e s t

T l ~ c arrangement o f t h e dampers f o r t h e f o u r t h t e s t i s

i l l u s t r n t e d i n F i g u r e 5 ( t a k e n a t t h e end o f t h e t e s t ) . They were i d c r l t i f i c t l hy NllC numhers, t h e one on t h e l e f t ( m u l t i - b l a d e w i t h c e n t r-c 111111 1 i o n ) be ing No. 101 and t h e m u l t i - b l a d e one on t h e r i g h t

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being No. 103. The upper o f t h e two s i n g l e - b l a d e dampers i n t h e c e n t r e was No. 206 and t h e lower was No. 106.

Heavy wrought i r o n caps were a g a i n mounted o v e r t h e f u r n a c e thermocouples and t h e f u r n a c e p r e s s u r e was a g a i n maintained p o s i t i v e a t approximately 5 . 1 mm (0.2 i n . ) W . G . f o r t h e 2-hr p e r i o d w i t h t h e e x c e p t i o n o f t h e f i r s t few minutes o f t e s t when it was s l i g h t l y lower.

In t h i s t e s t , t h e f u r n a c e c o n t r o l l e r f a i l e d t o f u n c t i o n f o r t h e f i r s t 7 1/2 min and t h e f u e l s u p p l y was maximum d u r i n g t h i s p e r i o d . The f u r n a c e reached a t e m p e r a t u r e o f 932OC a t t h i s time whereas t h e approved curve p r e s c r i b e s a v a l u e o f about 660°C. The h i g h e s t r e s u l t i n g unexposed f a c e t e m p e r a t u r e was on t h e m u l t i - b l a d e damper with c e n t r e mullion (No. 101) and was 866OC. F i g u r e s 2, 3 and 4 show t h a t t h i s t e m p e r a t u r e was i n f a c t h i g h e r t h a n any v a l u e recorded d u r i n g any p r e v i o u s t e s t . A s i n d i c a t e d i n F i g u r e 5 ( t a k e n a t t h e end o f t h e 2-hr t e s t ) , t h i s s u b s t a n t i a l i n i t i a l thermal shock d i d n o t m a t e r i a l l y damage e i t h e r t h e

m u l t i - b l a d e damper w i t h t h e c e n t r e mullion o r t h e two s i n g l e - b l a d e dampers. The second b l a d e o f t h e o t h e r m u l t i - b l a d e damper

(No. 103, extreme r i g h t i n F i g u r e 5) warped a p p r e c i a b l y d u r i n g t h e f i r s t 8 min o f t h e t e s t . To confirm t h a t t h i s damage was p r i m a r i l y t h e r e s u l t o f e x c e s s i v e thermal shock, a d u p l i c a t e was included i n t h e s e r i e s s u b j e c t e d t o t h e f i f t h t e s t .

F i f t h T e s t

The f i f t h t e s t was c a r r i e d o u t with t h e f u r n a c e thermocouples capped a s p r e v i o u s l y and a p o s i t i v e p r e s s u r e o f 5 . 1 mm '10 p e r c e n t (0.2 i n . ) W.G. was maintained d u r i n g t h e 2-hr t e s t p e r i o d e x c e p t f o r t h e f i r s t 2 min o f t e s t . The dampers t e s t e d a r e i l l u s t r a t e d i n F i g u r e 6 ( a f t e r t e s t ) . They comprised a m u l t i - b l a d e damper with c e n t r e mullion ( l e f t , NRC No. 201), a m u l t i - b l a d e damper i d e n t i f i e d a s NRC No. 203 ( c e n t r e ) and a d u p l i c a t e

(NRC No. 104) o f t h e m u l t i - b l a d e damper (No. 103) t h a t performed p o o r l y i n t h e f o u r t h t e s t .

17igurc 7 i s a t i m e - t e m p c r a t u r e r e c o r d o f a thermocouple a t t : ~ c h c r l to clamper No. 104 which cxpcrienced t h e h i g h e s t t c n ~ p c r a t u r c s o f t h c f o u r . A s h a s bcen s a i d o f t h c o t h c r t c m p c r n t u r c r e c o r d s , u n d e s i r a b l y high temperatures p r c v a i l c d d u r i n g t h c 2-hr t e s t p e r i o d .

S i x t h T e s t

The s i x t h t e s t was c a r r i e d o u t with f i v e of t h e n i n e t y p e s of damper p r e v i o u s l y examined, t o determine t h e e f f e c t o f a 2-hr cxposure t o more moderate t e m p e r a t u r e s t h a n p r e v i o u s l y .

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F i g u r e 8 i l l u s t r a t e s t h e t e s t a r r a n g e m e n t . I t was n o t p o s s i b l e t o mount a l l t h e dampers a t one l e v e l a s f o r p r e v i o u s t e s t s , b u t t h i s f e a t u r e was c o n s i d e r e d u n i m p o r t a n t b e c a u s e t h e i n f l u e n c e o f p o s i t i v e p r e s s u r e ( o r t h e magnitude o f i t ) had proved minimal. Two m u l t i - b l a d e dampers w i t h c e n t r e m u l l i o n (Nos. 102 and 202) were mounted a t t h e l e v e l o f t h e p r e v i o u s i n s t a l l a t i o n s and t h e p r e s s u r e a t m i d - h e i g h t was m a i n t a i n e d a t 5 . 1 mm

+ l o

p e r c e n t

(0.2 i n . ) W.G. from w i t h i n a few m i n u t e s o f t h e s t a r t o f t h e t e s t . Two o f t h e r e m a i n i n g t h r e e dampers were s i n g l e - b l a d e and were i d e n t i f i e d a s Nos. 105 and 205; t h e t h i r d was m u l t i - b l a d e and i d e n t i f i e d a s No. 204. The e q u i l i b r i u m p r e s s u r e d i f f e r e n c e

m a i n t a i n e d a t t h e h i g h e r l e v e l was a p p r o x i m a t e l y 6 . 1 mm (0.24 i n . )

W. G .

The g a s ( f u e l ) d i s t r i b u t i o n t o t h e e i g h t y f u r n a c e b u r n e r s was n o t o p t i m a l and t h u s t h e f u r n a c e t e m p e r a t u r e was n o t s p a t i a l l y uniform. The a v e r a g e t e m p e r a t u r e w i t h i n t h e f u r n a c e was p e r m i t t e d t o f o l l o w t h e ASTM El19 c u r v e up t o 540°C and was t h e n m a i n t a i n e d c o n s t a n t a t t h a t l e v e l . New f u r n a c e t h e r m o c o u p l e s , o f a d i f f e r e n t t y p e from t h o s e p r e v i o u s l y u s e d , had been i n s t a l l e d p r i o r t o t h e t e s t . Each t h e r m o c o u p l e , a s p u r c h a s e d , i n c l u d e d i t s own c a p p i n g , and a l t h o u g h it complied w i t h one o f t h e s t y l e s p e r m i t t e d by ASTM E119, it i n v o l v e d much l e s s m e t a l l i c mass and a minimum o f

i n s u l a t i o n . T h i s would minimize t h e r m a l l a g .

F i g u r e 9 i s a r e c o r d o f t h e t e m p e r a t u r e extremes t h a t

p r e v a i l e d on t h e unexposed s u r f a c e s o f t h e dampers. Examination o f t h e t e m p e r a t u r e r e c o r d s o f t h e t h e r m o c o u p l e s w i t h i n t h e

f u r n a c e shows t h a t t e m p e r a t u r e v a r i a t i o n i s v i r t u a l l y a t t r i b u t a b l e t o f u r n a c e t e m p e r a t u r e v a r i a t i o n .

A s i n d i c a t e d by t h e f l o w t e s t s , r e p o r t e d l a t e r , t h e v a r i o u s e x p o s u r e s d i d n o t r e s u l t i n any a p p r e c i a b l e warping o f t h e dampers o r i n any development o f o t h e r e x t r a n e o u s l e a k a g e .

LEAKAGE TESTS

A i r l c a k n g c t e s t s were conducted on each d:impcr b e f o r e and : l f t c r t h e f i r e e x p o s u r e t e s t . F i g u r e 10 shows t h e t c s t

arr;lngcmcnt f o r measuring t h c a i r t i g h t n e s s of t h e dampers. I t

consisted o f a s e a l e d plywood box (3 by 4 by 6 f t ) w i t h a l a r g e opcning on one s i d e f o r i n s t a l l i n g t e s t dampers. The o p p o s i t e s i d e o f t h e box was c o n n e c t e d t o a round d u c t w i t h t h e end of t h e d u c t c o n n e c t e d t o t h e s u c t i o n s i d e o f a f a n . The d i s c h a r g e s i d e o f t h e f a n was c o n n e c t e d t o a s h o r t d u c t w i t h a damper t o c o n t r o l t h c r a t c o f a i r f l o w t h r o u g h t h e t e s t damper. With t h i s

a r r a n g e m e n t , t h e a i r was drawn from t h e room t h r o u g h t h e t e s t

damper, i n t o t h e l a r g e box, and o u t t h r o u g h t h e d u c t and f a n and back t o t h e room.

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Three d i f f e r e n t d u c t - f a n a r r a n g e m e n t s were used t o c o v e r t h e e x p e c t e d r a n g e o f l e a k a g e r a t e s t h r o u g h t h e t e s t dampers. They a r e a s f o l l o w s :

Fan Duct Duct Method o f

C a p a c i t y Diameter Length Flow Measurement

c fm i n . i n .

350 4 96 l a m i n a r flow element

800 8 108 t o t a l p r e s s u r e a v e r a g i n g t u b e 3200 12 120 t o t a l p r e s s u r e a v e r a g i n g t u b e

Each d u c t system, which p e r m i t t e d f l o w r a t e measurement w i t h a s i n g l e p r e s s u r e r e a d i n g , was c a l i b r a t e d u s i n g a 10 p o i n t l o g - l i n e a r p i t o t t r a v e r s e . A s t a t i c p r e s s u r e t a p was i n s e r t e d i n t h e w a l l o f t h e l a r g e box t o measure t h e p r e s s u r e d r o p a c r o s s t h e t e s t damper w i t h a p r e s s u r e t r a n s d u c e r . The p r e s s u r e r e a d i n g s were made w i t h a diaphragm t y p e p r e s s u r e t r a n s d u c e r ( s e n s i t i v i t y o f 0 . 0 5 mm; 0.002 i n . W.G.).

The l a r g e box was t e s t e d f o r a i r - t i g h t n e s s by o p e r a t i n g t h e f a n a f t e r s e a l i n g t h e opening o f t h e t e s t damper. The l e a k a g e flow through t h e box was l e s s t h a n 5 cfm and t h e d i f f e r e n c e i n p r e s s u r e between t h e room and i n s i d e t h e box r o s e r a p i d l y . The t e s t was t e r m i n a t e d a t 25.4 mm ( 1 i n . ) W.G. w i t h t h e p r e s s u r e d i f f e r e n c e r e a d i n g r i s i n g , which i n d i c a t e d t h a t t h e l a r g e box was v i r t u a l l y a i r - t i g h t .

The t e s t f i r e dampers were i n s t a l l e d i n t h e l a r g e box w i t h t h e l o n g s i d e o f t h e b l a d e s i n t h e h o r i z o n t a l p o s i t i o n . The dampers were c l o s e d by d i s c o n n e c t i n g t h e f u s i b l e l i n k s and a l l o w i n g them t o c l o s e e i t h e r by g r a v i t y o r s p r i n g a c t i o n . I n some c a s e s t h e dampers were c l o s e d manually because t h e y d i d n o t c l o s e c o m p l e t e l y on t h e i r own.

I n i t i a l t e s t s were conducted t o check t h e v a r i a t i o n i n a i r l e a k a g e r a t e s t h a t c o u l d o c c u r w i t h t h e manner o f damper c l o s u r e . The f a n flow was a d j u s t e d , w i t h t h e c o n t r o l damper, t o m a i n t a i n a p r e s s u r e d i f f e r e n c e o f 12.7 mm (0.50 i n . ) W.G. a c r o s s t h e damper and t h c c o r r e s p o n d i n g l e a k a g e flow t h r o u g h t h e damper was

mcnsured. The damper was t h e n opened and c l o s e d and t h e a i r lcnkngc flow was measured a t t h e same p r e s s u r e d i f f e r e n c e . T h i s proccdurc was r e p e a t e d s i x t i m e s .

'I'his was followed by t e s t s t o d e t e r m i n e t h e a i r l e a k a g e

c h a r a c t e r i s t i c o f t h e damper. The a i r l e a k a g c f l o w s were measured a t p r c s s u r c d j f f e r c n c c s o f 2.54 t o 1 2 . 7 mm (0.10 t o 0.50 in.) W.G. a t an incrcmcnt o f 2.54 mm (0.10 i n . ) W.G.

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Method f o r E v a l u a t i o n o f A i r - T i g h t n e s s

The r e l a t i o n s h i p between t h e a i r l e a k a g e flow and t h e p r e s s u r e d i f f e r e n c e a c r o s s t h e t e s t damper can be e x p r e s s e d a s f o 1 lows : where Q = l e a k a g e f l o w , cfm/sq f t o f damper a r e a A = a r e a o f damper, s q f t n C = flow c o e f f i c i e n t , c f m / ( i n . W.G.) AP = p r e s s u r e d i f f e r e n c e a c r o s s damper, i n . W.G. n = flow exponent.

The flow c o e f f i c i e n t (C) and flow exponent (n) of t h e above e q u a t i o n d e f i n e t h e a i r l e a k a g e c h a r a c t e r i s t i c s o f t h e damper. During t h e a i r l e a k a g e t e s t s f i v e s e t s of v a l u e s f o r l e a k a g e flow

(Q) and p r e s s u r e d i f f e r e n c e (AP) were o b t a i n e d . The damper a r e a s (A) a l s o were c a l c u l a t e d , b a s e d on t h e i n s i d e dimensions of t h e frame. The v a l u e s o f flow c o e f f i c i e n t and exponent were c a l c u l a t e d u s i n g t h e method o f l e a s t s q u a r e s . The a i r - t i g h t n e s s can be e x p r e s s e d i n t e r m s o f l e a k a g e opening a s a p e r c e n t a g e o f damper a r e a by u s i n g t h e e q u a t i o n f o r flow o f a i r , a t t h e s t a n d a r d c o n d i t i o n , t h r o u g h a sharp-edged o r i f i c c : 1 Q = 2 4 0 0 a ( A ~ ) ' ( 2 ) whcrc a = l e a k a g e a r e a , s q f t / s q f t o f damper a r e a S u b s t i t u t i n g Q o f Eq. (2) i n Eq. (1) g i v e s

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M u l t i p l y i n g a o f Eq. (3) by 100 g i v e s t h e l e a k a g e a r e a a s a p e r c e n t a g e o f damper a r e a . I f t h e v a l u e o f n f o r a damper i s e q u a l t o 1 / 2 , t h e n t h e v a l u e o f a would be i n d e p e n d e n t o f A P and i t s flow c h a r a c t e r i s t i c would-be s i m i l a r t o t h a t o f an o r i f i c e . I f t h e v a l u e o f n i s n o t e q u a l t o 1 / 2 , however, t h e v a l u e o f - a would depend upon A P .

Leakage T e s t R e s u l t s

T a b l e 1 g i v e s t h e r e s u l t s o f t h e a i r l e a k a g e t e s t s b e f o r e and a f t e r e a c h f i r e endurance t e s t . They a r e e x p r e s s e d i n t e r m s o f p e r c e n t a g e o f damper a r e a ( i n s i d e dimensions o f frame) and a r e based on Eq. (3) w i t h a v a l u e o f 0 . 3 0 i n . W.G. f o r A P . Values o f t h e f l o w exponent ranged from 0.47 t o 0.60 w i t h a mean v a l u e o f 0 . 5 3 f o r a l l dampers b e f o r e and a f t e r t h e f i r e t e s t s , i n d i c a t i n g t h a t t h e l e a k a g e o p e n i n g s behaved much l i k e a s h a r p edged o r i f i c e .

The v a r i a t i o n i n l e a k a g e flow r a t e w i t h r e p e a t e d c l o s u r e , a p p e a r s t o depend on t h e damper d e s i g n w i t h r e g a r d t o s e a l between b l a d e s and s t o p s . The v a r i a t i o n s i n l e a k a g e flow r a t e f o r two c u r t a i n t y p e dampers from one m a n u f a c t u r e r were 11 and 19 p e r c e n t b u t f o r a n o t h e r m a n u f a c t u r e r t h e y were 4 and 6 p e r c e n t . For b l a d e t y p e dampers, t h e s e v a r i a t i o n s were 10 t o 38 p e r c e n t f o r dampers from one m a n u f a c t u r e r and 0 t o 3 p e r c e n t f o r t h o s e from a n o t h e r . The l a t t e r were p r o v i d e d w i t h s p r i n g c l i p o r l a t c h i n a d d i t i o n t o t h e b l a d e s t o p a t t h e bottom, which a p p e a r e d t o have produced c o n s i s t e n t a i r l e a k a g e r a t e s .

T a b l e 1 g i v e s t h e l e a k a g e a r e a s f o r b l a d e t y p e dampers t e s t e d w i t h t h e d i r e c t i o n o f a i r flow from t h e s i d e w i t h t h e damper

c o n t r o l mechanism t o t h e o p p o s i t e s i d e . T h i s i s t h e e x p e c t e d d i r e c t i o n o f a i r flow f o r smoke s h a f t a p p l i c a t i o n . No such d i s t i n c t i o n c o u l d be made f o r c u r t a i n t y p e dampers a s b o t h s i d e s o f t h e dampers were s i m i l a r i n c o n s t r u c t i o n . Upstream s i d e s o f t h e s e dampers were i d e n t i f i e d s o t h a t t h e y would be t e s t e d i n t h e same manner b e f o r e and a f t e r t h e f i r e t e s t .

T a b l e 1 g i v e s a n i n d i c a t i o n ( p r i o r t o f i r e t e s t i n g ) o f t h e v a r i a t i o n i n l e a k a g e v a l u e s t h a t can b e e x p e c t e d w i t h t y p e of damper, m a n u f a c t u r e r and, a s dampers were p r o c u r e d i n p a i r s ,

bctwcen two i d e n t i c a l dampers. The l e a k a g e v a l u e s f o r a l l dampers t c s t c d v a r i e d from 0.44 t o 2.85 p e r c e n t o f t h e damper a r e a .

Maximum l e a k a g c v a l u e s o b t a i n e d were 1.42 p e r c e n t f o r t h e c u r t a i n t y p c , 2 . 6 1 p e r c e n t f o r t h e s i n g l e - b l a d e t y p e , 2.43 p e r c e n t f o r t h c m u l t i - b l a d e t y p e , and 2.85 p e r c e n t f o r t h e m u l t i - b l a d e w i t h c e n t r c m u l l i o n t y p e . The maximum d i f f e r e n c e between two i d e n t i c a l drrmpcrs was 0.72 p e r c e n t . The a v c r a g e d i f f e r e n c e was a b o u t 0 . 3 0

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A f t e r t h e i n i t i a l a i r leakage t e s t s , t h e f i r e dampers were i n s t a l l e d i n t h e wall f u r n a c e w i t h t h e upstream f a c e , a s t e s t e d f o r a i r leakage, exposed t o t h e room s i d e and s u b j e c t e d t o t h e f i r e endurance t e s t .

Tablc 1, which a l s o g i v e s t h e r e s u l t s o f t h e a i r leakage t e s t s a f t e r t h c f i r e t e s t s , i n d i c a t e s t h a t t h e i n c r e a s e i n

leakage n r c a s f o r t h e c u r t a i n ty-pe dampers was g r e a t e r by 0 . 5 t o 1 . 0 p e r c e n t when t h e f u r n a c e was under p o s i t i v e p r e s s u r e a s compared t o n e g a t i v e p r e s s u r e . With t h e f u r n a c e under n e g a t i v e p r c s s u r e , t h e a i r i n t h e room, induced through t h e f i r e damper, tended t o c o o l t h e damper whereas an o p p o s i t e e f f e c t took p l a c e when t h e f u r n a c e was under p o s i t i v e p r e s s u r e .

A f t e r t h e f i r e t e s t , t h e i n c r e a s e i n leakage a r e a s of t h e c u r t a i n t y p e dampers ranged from -0.06 t o 1.34 p e r c e n t o f t h e damper a r e a , when t h e f u r n a c e was under p o s i t i v e p r e s s u r e . The i n c r e a s e i n leakage a r e a s a f t e r a 2-hr f i r e endurance t e s t f o r t h e b l a d e t y p e dampers ranged from -0.08 t o 5 . 1 p e r c e n t o f t h e damper a r e a . The g r e a t e s t i n c r e a s e s o c c u r r e d f o r t h e m u l t i - b l a d e t y p e dampers followed by m u l t i - b l a d e t y p e w i t h c e n t r e m u l l i o n . The l e a s t o c c u r r e d f o r t h e s i n g l e - b l a d e t y p e dampers. The maximum through c l e a r a n c e s were l e s s t h a n t h e 0.75 i n . s p e c i f i e d by ULC

S112. The maximum gap between b l a d e s was a l s o l e s s than t h i s v a l u e except f o r damper No. 103 which had a 2 i n . gap caused by s e v e r e bowing o f t h e t o p b l a d e .

The i n c r e a s e i n a i r leakage v a l u e s f o r t h e t e s t dampers, t e s t e d with maximum f u r n a c e t e m p e r a t u r e s o f 540°C ( t e s t No. 6 ) , were c o n s i d e r a b l y l e s s , with v a l u e s o f -0.33 t o 0.14 p e r c e n t of t h e damper a r e a . The leakage v a l u e s were e s s e n t i a l l y t h e same a s t h o s e b e f o r e t h e f i r e t e s t s .

CONCLUSIONS

I n drawing t h e f o l l o w i n g c o n c l u s i o n s , it must be r e i t e r a t e d t h a t t e s t i n g was c a r r i e d o u t i n t h e c o n t e x t o f smoke s h a f t s and t h a t t h e dampers procured were n o t s p e c i f i c a l l y designed f o r t h i s : ~ p p l i c a t i o n .

I . '1'cmpcr;lturcs a t t h e unexposed f a c e s of t h e dampers were ~ ~ n a c c c p t n b l y h i g h f o r most smoke s h a f t a p p l i c a t i o n s

.

Smoke

s h a f t s might well be f u l l y f i r e involved and i n u n s p r i n k l c r e d lxriltlings h i g h t e m p e r a t u r e s on t h e f l o o r spacc s i d c o f t h e danlpcrs might c r e a t c s c r i o u s r i s k o f i g n i t i o n on c v c r y f l o o r s c r v e d by t h c smoke s h a f t above t h c f i r e f l o o r .

2 . Only i n t h e c a s c o f one p a r t i c u l a r model of c u r t a i n dampcr d i d f i r e exposure cause damage ( f a i l u r e o f a r i v e t ) o f a n a t u r c

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that might have proved serious. In all other cases the

essential components held together and post-fire-test leakage area was generally below 4 per cent, excepting two cases when it was 5.53 per cent and 7.29 per cent.

3. Operating the furnace under positive rather than negative pressure gave slightly but not substantially greater leakage areas.

4 . Restricting the maximum furnace temperature to 540°C avoided appreciable increase in leakage area due to a fire test.

5. Test No. 4 indicated that thermal shock, that is, rapid and substantial temperature rise, is most likely to give increased leakage.

6. Disregarding the rivet failure, the curtain dampers in general gave less leakage increase due to fire test than did other types.

ACKNOWLEDGEMENTS

The authors are indebted to R.G. Evans for conducting the air leakage tests and to J.E. Berndt,

P.

Huot and

R.

Lamirande for carrying out the fire tests.

REFERENCE

1. "Standard for Fire Dampers," Underwriters' Laboratories of Canada, ULC - S112, 1973.

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TABLE I

curtain

curtain

RFSULTS OF A I R LTAKACI: TliSTS

*' Betorc f i r r to?.t No. 3

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(a) Unexposed s i d e , a f t e r t e s t .

A

-

NO. 302779 B

-

NO. 320948 C

-

NO. 333307

(b) D e t a i l o f c e n t r e damper (No. 320948) a f t e r t e s t ( f u r n a c e s i d e ) . Figure 1 F i r s t S e r i e s of Dampers Tested

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F I G U R E 2 T I M E - T E M P E R A T U R E C U R V E A T T H E U N E X P O S E D F A C E O F D A M P E R N O . 302779 ( F I R S T T E S T ) 900 800 700 600 500 400 300 200 100 0 0 T I M E , M I N U T E S F I G U R E 3 T I M E , M I N U T E S

-

I I I I I I I I I I I T I M E - T E M P E R A T U R E C U R V E A T T H E U N E X P O S E D F A C E O F D A M P E R N O . 295596 ( S E C O N D T E S T ) 120 - -

-

-

-

-

-

-

-

-- 1

-

-

- - - I I I I I I I I I I I 10 20 30 4 0 50 60 70 80 9 0 100 I10

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F I G U R E 4 T I M E - T E M P E R A T U R E C U R V E A T T H E U N E X P O S E D F A C E O F D A M P E R N O . 3 0 2 7 7 9 ( T H I R D T E S T ) R R 5 4 6 2 - 3 9 0 0 8 0 0 7 0 0 6 0 0 0 W Ir 5 0 0 - 3 + 4 II: w 4 0 0 - a

z

+ 3 0 0 2 0 0 1 0 0 0 0 T I M E , M I N U T E S 1 2 0 - 1 I 1 1 I I I I I I I - - / - - - - - -- J - - - - - A I I I I I I I I I I I 1 0 20 3 0 4 0 5 0 6 0 70 80 9 0 1 0 0 1 1 0

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F i g u r e 5 T e s t Arrangement f o r F o u r t h T e s t (unexposed s i d e , a f t e r t e s t )

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A - No. 201 B - No. 203 C - NO. 104

F i g u r e 6 Views o f F i f t h T e s t S e r i e s o f Dampers (unexposed s i d e , a f t e r t e s t )

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O 0 1 0 2 0 30 4 0 5 0 6 0 7 0 8 0 9 0 100 1 1 0 120 T I M E , M I N U T E S

F I G U R E 7

T I M E - T E M P E R A T U R E C U R V E A T T H E U N E X P O S E D F A C E O F D A M P E R N O . 1 0 4 ( F I F T H T E S T )

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F i g u r e 8 T e s t Arrangement f o r S i x t h T e s t (unexposed s i d e , a f t e r t e s t )

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I I I I I I I I I I I - - - - - -

.-

--

#/-.--#- -7 ( T O P R I G H T D A M P E R - F i c . 8 ) - ( H O T T O M L E T T D A M P E R - F I G . 8 1 - - I I I I I I I I I I I T I M E . M I N U T E S F I G U R E 9 T I M E - T E M P E R A T U R E C U R V E S A T T H E U N E X P O S E D F A C E S O F D A M P E R S N O . 1 0 5 A N D N O . 2 0 2 ( S I X T H T E S T ) 8 R 5 4 6 2 - 5 S E A L E D P L Y W O O D 0 0 X T E S T D A M P E R F O R S T A T I C P R E S S U R E T A P T O R O O M A I R F I G U R E 1 0 T E S T S E T U P F O R M E A S U R I N G A I R - T I G H T N E S S O F D A M P E R S

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