Experimental fire tower studies of elevator pressurization systems for smoke control

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Experimental fire tower studies of elevator pressurization systems for

smoke control

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Experimental Fire Tower Studies of Elevator

Pressurization Systems for Smoke Control

by

G.T. Tamura and

J.H.

Klote

ANALYZED

Reprinted from

ASHRAE

Transactions 1987

Vol. 93,

Pt.

2 p. 2235-2256

(IRC Paper No. 1548)

NRCC 291 21

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-On a effectuC des essais dans la tour experimentale d'incendie du Conseil national de

recherches du Canada afin d'ktudier le mouvement de la furnee dans les puits d'ascenseurs

sous I'effet d'un gros incendie, et de determiner la capacitk des installations mkaniques de

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contrbler la pression pour parer h la perte de pression due h l'ouverture des portes. On a

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comportant soit un debit variable d'alimentation d'air avec contrble en retour, soit des

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pression, les valeurs mesurCes et calculCes des debits d'alimentation d'air et des Ccarts de

pression concordaient gCnCralement.

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EXPERIMENTAL FIRE TOWER STUDIES

OF ELEVATOR PRESSURIZATION

SYSTEMS FOR

SMOKE CONTROL

G.T.

Tamura,

P.E.

J.H. Klote, P.E., D.Sc.

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EXPERIMENTAL FIRE TOWER STUDIES

OF ELEVATOR PRESSURIZATION

SYSTEMS FOR SMOKE CONTROL

G.T.

Tarnura,

P.E.

J.H.

Klote,

P.E.,

D.Sc.

ASHRAE Fellow ASHRA E Member

ABSTRACT

T e s t s were conducted i n t h e e x p e r i m e n t a l f i r e tower a t t h e N a t i o n a l Research Council of Canada t o s t u d y smoke movement through e l e v a t o r s h a f t s caused by a l a r g e f i r e and t o determine t h e e f f e c t i v e n e s s of mechanical p r e s s u r i z a t i o n i n keeping t h e e l e v a t o r s h a f t and l o b b i e s t e n a b l e f o r e v a c u a t i o n of t h e handicapped and f o r use by f i r e f i g h t e r s . The t e s t s i n d i c a t e d t h a t p r e s s u r e c o n t r o l is r e q u i r e d t o cope w i t h l o s s of p r e s s u r i z a t i o n due t o open doors. Equations were developed t o a s s i s t i n d e s i g n i n g p r e s s u r e c o n t r o l systems i n v o l v i n g e i t h e r a v a r i a b l e

supply a i r r a t e w i t h feedback c o n t r o l o r r e l i e f dampers i n t h e w a l l s of t h e e l e v a t o r s h a f t o r l o b b i e s . T e s t s conducted i n t h e tower i n d i c a t e d t h a t f o r both methods of p r e s s u r e c o n t r o l , comparison of measured and c a l c u l a t e d v a l u e s of supply a i r r a t e s and p r e s s u r e d i f f e r e n c e s a r e i n good agreement.

INTRODUCTION

It is a g e n e r a l p r a c t i c e t o d i s c o u r a g e occupants from u s i n g e l e v a t o r s a s means of escape d u r i n g a f i r e by warning s i g n s placed a d j a c e n t t o t h e doors and by a u t o m a t i c e l e v a t o r r e c a l l t o t h e ground f l o o r upon f i r e s i g n a l s . I f , however, one o r more e l e v a t o r s can be made s a f e from t h e e f f e c t s of f i r e , t h e y can be used t o s e r v e a v i t a l f u n c t i o n i n a i d i n g f i r e f i g h t e r s and i n e v a c u a t i n g handicapped people. Such an e l e v a t o r must have c o n t r o l s and power s u p p l i e s t h a t a r e r e l i a b l e , and t h e i r l o b b i e s and s h a f t must be p r o t e c t e d a g a i n s t f i r e and smoke.

To develop smoke c o n t r o s a f e e l e v a t o r , a j o i n t p r o j e c t (NRCC) and t h e National Bureau

1 technology f o r e l e v a t o r s as one of t h e requirements of a f i r e - was undertaken by t h e N a t i o n a l Research Council of Canada of Standards (NBS) i n t h e United S t a t e s . I n i t i a l s t u d i e s involved a computer a n a l y s i s of s e v e r a l p o s s i b l e smoke c o n t r o l systems ( K l o t e and Tamura

1986). The r e s u l t s of t h e a n a l y s i s conducted f o r both summer and w i n t e r and f o r c e r t a i n open- door c o n d i t i o n s i n d i c a t e d t h a t a l l systems c o n s i d e r e d , e x c e p t f o r t h e one w i t h feedback c o n t r o l of supply a i r f o r e l e v a t o r s h a f t p r e s s u r i z a t i o n , f a i l e d t o m a i n t a i n t h e r e q u i r e d p r e s s u r i z a t i o n when some combination of doors was open. It was a l s o noted t h a t t h e r e a r e probably o t h e r systems capable of p r o v i d i n g adequate smoke c o n t r o l .

This paper d e a l s with t h e follow-up s t u d i e s i n t h e e x p e r i m e n t a l f i r e tower of t h e N a t i o n a l F i r e L a b o r a t o r i e s (NRCC). The t e s t s involved examining t h e smoke movement p a t t e r n caused by t h e temperature e f f e c t of f i r e and t h e e f f e c t i v e n e s s of t h e mechanical

p r e s s u r i z a t i o n e i t h e r of t h e e l e v a t o r s h a f t o r e l e v a t o r l o b b i e s i n t h e e l e v a t o r s h a f t l l o b b y u s a b l e . Equations were developed f o r d e s i g n i n g p r e s s u r i z a t i o n systems w i t h p r e s s u r e c o n t r o l

t o cope w i t h p r e s s u r e l o s s due t o some open door c o n f i g u r a t i o n s . The types of p r e s s u r e

c o n t r o l system examined were feedback c o n t r o l of supply a i r r a t e f o r p r e s s u r i z a t i o n and r e l i e f

G.T. Tamura, I n s t i t u t e f o r Research i n Construct i o n , N a t i o n a l Research Council of Canada, Ottawa, and J.H. K l o t e , Center f o r F i r e Research, National Bureau of S t a n d a r d s , G a i t h e r s b u r g ,

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dampers i n t h e w a l l s of e i t h e r t h e e l e v a t o r s h a f t o r e l e v a t o r fobby i n t h e c a s e of l o b b y p r e s s u r i z a t i o n . These e q u a t i o n s were v a l i d a t e d w i t h t e s t s i n t h e e x p e r i m e n t a l f i r e tower. They w i l l p r o b a b l y be u s e f u l t o d e s i g n e r s ; t h i s p a p e r , however, does n o t d e v e l o p a c o y p l e t e d e s i g n methodology f o r e l e v a t o r smoke c o n t r o l .

DESCRIPTION OF THE EXPERIMENTAL FIRE TOWER

The f i r e tower ( F i g u r e 1 ) i s p a r t of t h e e x p e r i m e n t a l f a c i l i t i e s of t h e N a t i o n a l F i r e

L a b o r a t o r y l o c a t e d between C a r l e t o n P l a c e and Almonte, O n t a r i o , a b o u t 40 m i l e s ( 6 0 km) west of Ottawa. The 10-story tower c o m p r i s e s a n e x p e r i m e n t a l tower and an a t t a c h e d o b s e r v a t i o n tower. The t y p i c a l f l o o r h e i g h t i s 8.5 f t ( 2 . 6 m) e x c e p t f o r t h e f i r s t and second f l o o r s , which a r e 12 f t (3.6 m). Both t o w e r s $re c o n s t r u c t e d of m o n o l i t h i c r e i n f o r c e d c o n c r e t e ( t h i c k n e s s of 8 i n [200 mm]). The p l a n v i e w of a t y p i c a l f l o o r is shown i n F i g u r e 2.

The o b s e r v a t i o n tower c o n t a i n s a f r e i g h t e l e v a t o r , s t a i r w a y , a workspace f o r

i n s t r u m e n t s , and d a t a a c q u i s i t i o n u n i t s f o r m o n i t o r i n g f i r e e x p e r i m e n t s . It i s p r o t e c t e d by a f i r e w a l l and f i r e d o o r s w i t h s m a l l f i x e d w i r e d - g l a s s o b s e r v a t i o n windows. An i n d e p e n d e n t a i r s y s t e m m a i n t a i n s a c o m f o r t a b l e t e m p e r a t u r e i n w i n t e r and p r e s s u r i z e s t h e o b s e r v a t i o n tower t o p r e v e n t i n g r e s s of combustion p r o d u c t s from t h e f i r e tower.

The e x p e r i m e n t a l tower c o n t a i n s a l l t h e s h a f t s and o t h e r f e a t u r e s n e c e s s a r y t o s i m u l a t e a i r and smoke movement p a t t e r n s of a t y p i c a l m u l t i s t o r y b u i l d i n g , i n c l u d i n g t h e e l e v a t o r , s t a i r , smoke e x h a u s t , s e r v i c e , s u p p l y , and r e t u r n a i r s h a f t s . The e l e v a t o r and s t a i r s h a f t s a r e f u l l - s i z e d , b u t t h e e l e v a t o r s h a f t , a t p r e s e n t , h a s no c a r o r h o i s t i n g a p p a r a t u s , w h i l e t h e s t a i r s h a f t is equipped w i t h a s t a n d a r d s t a i r c a s e . A s u r r o u n d i n g c o r r i d o r i s o l a t e s t h e group of s h a f t s from t h e e x t e r i o r w a l l s , c r e a t i n g a t y p i c a l c e n t e r c o r e . A l l j o i n t s of t h e c o n c r e t e s t r u c t u r e a r e s e a l e d t o minimize u n c o n t r o l l e d a i r l e a k a g e s . The e x t e r i o r w a l l s and w a l l s of v e r t i c a l s h a f t s a r e p r o v i d e d w i t h v a r i a b l e o p e n i n g s t h a t c a n be set t o p r o v i d e d e s i r e d l e a k a g e a r e a s of t y p i c a l b u i l d i n s. Two propane g a s b u r n e r s e t s , e a c h c a p a b l e of

f,

p r o d u c i n g h e a t a t an o u t p u t of 8.56 x 10 Btu/h (2.5 MW), a r e l o c a t e d on t h e second f l o o r burn

a r e a w i t h t h e g a s t r a i n r i g s l o c a t e d i m m e d i a t e l y below on t h e ground f l o o r . The second f l o o r I i s c o m p l e t e l y p r o t e c t e d w i t h h i g h t e m p e r a t u r e i n s u l a t i o n t o p r e v e n t t h e c o n c r e t e from t h e r m a l

damage of t h e c o n c r e t e . 1

I

A s e p a r a t e s t r u c t u r e a d j a c e n t t o t h e tower ( F i g u r e 3 ) h o u s e s t h e a i r moving and h e a t i n g

1

p l a n t of t h e e x p e r i m e n t a l t o w e r ; t h e a i r d u c t s b e i n g c a r r i e d underground t h r o u g h a s h o r t

t u n n e l t o t h e bottom of t h e e x p e r i m e n t a l f i r e tower. There a r e two a i r systems. The f i r s t h a n d l e s t h e main a i r s u p p l y and h e a t i n g l o a d . It n o r m a l l y o p e r a t e s i n t h e r e c i r c u l a t i o n mode, but i t can be o p e r a t e d on 100% o u t s i d e a i r and u s e d t o p r e s s u r i z e t h e e n t i r e b u i l d i n g . T h i s s y s t e m can a l s o be r u n i n a n e x h a u s t mode by u s i n g a s e p a r a t e v a r l a b l e - f l o w e x h a u s t f a n mounted a t t h e t o p of t h e r e t u r n a i r s h a f t . The second a i r s y s t e m s u p p l i e s o u t s i d e a i r , e i t h e r t o t h e e x p e r i m e n t a l s t a i r and e l e v a t o r s h a f t s o r t o v e s t i b u l e s i n t e r p o s e d between t h e e n t r a n c e s t o t h e s e s h a f t s a n d t h e b u r n a r e a . The a i r systems a r e o p e r a t e d from t h e f a n c o n t r o l room i n t h e a t t a c h e d s e r v i c e u n i t ( F i g u r e 3 ) . The a i r f l o w r a t e s i n t h e a i r d u c t s a r e measured w i t h e i t h e r m u l t i - p o i n t s e l f - a v e r a g i n g t o t a l p r e s s u r e t u b e s and t h e i r a s s o c i a t e d s t a t i c p r e s s u r e t a p s o r w i t h an o r i f i c e p l a t e . They were c a l i b r a t e d u s i n g t h e p i t o t t r a v e r s e method.

Temperatures a r e measured i n t e n d i f f e r e n t l o c a t i o n s on e a c h f l o o r u s i n g chrome-alumel thermocouples. A d d i t i o n a l t e m p e r a t u r e measurements a r e made i n t h e burn a r e a of t h e f i r e f l o o r . P r e s s u r e d i f f e r e n c e s a c r o s s t h e v a r i o u s w a l l s a r e measured u s i n g 18 s t a t i c p r e s s u r e t a p s (0.25 i n [6.3 mm] O.D. c o p p e r t u b i n g ) mounted f l u s h t o t h e w a l l s on e a c h f l o o r . A l l p r e s s u r e l i n e s a r e c o n n e c t e d t o a 24-port p r e s s u r e s w i t c h equipped w i t h a diaphragm-type m a g n e t i c r e l u c t a n c e p r e s s u r e t r a n s d u c e r and l o c a t e d on t h e same f l o o r i n t h e o b s e r v a t i o n a r e a . Carbon d i o x i d e c o n c e n t r a t i o n s a r e measured a t s i x l o c a t i o n s on e a c h f l o o r i n t h e s h a f t s , l o b b i e s , c o r r i d o r s , and b u r n a r e a by c o p p e r sampling t u b e s (0.25 i n [6.3 mm] O.D. c o p p e r

t u b i n g ) c o n n e c t e d t o a 12-port s a m p l i n g s w i t c h u n i t w i t h a n o n d i s p e r s i v e i n f r a r e d g a s < a n a l y z e r . A l l d e v i c e s of t h e t h r e e s y s t e m s a r e c o n t r o l l e d and monitored by a computer based

d a t a a c q u i s i t i o n and c o n t r o l system.

The c r o s s - s e c t i o n a l a r e a of t h e e l e v a t o r s h a f t , which r e p r e s e n t s a s i n g l e c a r s h a f t , i s 84 f t 2 (7.84 m2). Openings i n t h e w a l l s f o r t h e e l e v a t o r d o o r s a r e covered w i t h a movable plywood patlel t o p e r m i t a v a r i a b l e s i z e o p e n i n g up t o 6.0 f t 2 (0.56 m2) t o s i m u l a t e a l e a k a g e a r e a due t o an open e l e v a t o r door w i t h t h e c a r a t t h e opening. There i s a removable h a t c h a t

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t h e t o p of t h e e l e v a t o r s h a f t and an o u t s i d e v e n t c o n n e c t e d t o t h e bottom of t h e s h a f t a t t h e subgrade l e v e l , t o p e r m i t n a t u r a l v e n t i n g e i t h e r a t t h e t o p o r bottom of t h e s h a f t . Also a t t h e s u b g r a d e l e v e l t h e r e i s an opening f o r a i r s u p p l y t o t h e s h a f t . The e l e v a t o r lobby, whose a r e a i s 70 i t 2 (6.44 m2), is p r o v i d e d w i t h a s t a n d a r d f i r e door on a l l f l o o r s e x c e p t f o r t h e second f l o o r where t h e d o o r i s of p l a s t e r b o a r d w i t h a v e r t i c a l l e a k a g e s l o t i n t h e c e n t e r t o r e p r e s e n t t h e l e a k a g e a r e a of a t y p i c a l door. There is an o p e n i n g i n t h e w a l l of e a c h lobby t o s u p p l y a i r f o r lobby p r e s s u r i z a t i o n . A more d e t a i l e d d e s c r i p t i o n of t h e e x p e r i m e n t a l f i r e tower may be found i n Achakji (1987).

DESIGN APPROACH

The i n t e n t of a n e l e v a t o r p r e s s u r i z a t i o n s y s t e m i s t o p r e v e n t smoke m i g r a t i o n i n t o e l e v a t o r s h a f t s and l o b b i e s d u r i n g a f i r e . T h i s is done by d e v e l o p i n g p r e s s u r e s i n t h e l o b b i e s t h a t a r e s u f f i c i e n t t o overcome t h e a d v e r s e p r e s s u r e d i f f e r e n c e s caused by v a r i o u s mechanisms, s u c h a s w e a t h e r , t e m p e r a t u r e e f f e c t of f i r e , v e n t i l a t i o n s y s t e m s , and t h e p i s t o n e f f e c t c a u s e d by an e l e v a t o r i n motion. Lobbies s e r v e as t e m p o r a r y r e f u g e a r e a s f o r t h e h a n d i c a p p e d w a i t i n g t o be e v a c u a t e d by a n e l e v a t o r ; t h e y a l s o p r o t e c t t h e e l e v a t o r door and i t s c o n t r o l mechanism from t h e f i r e t e m p e r a t u r e . The h i g h e s t a d v e r s e p r e s s u r e d i f f e r e n c e f o r a g i v e n b u i l d i n g due t o a combination of t h e s e v a r i o u s mechanisms is t h e d e s i g n p r e s s u r e d i f f e r e n c e t h a t an e l e v a t o r s h a f t p r e s s u r i z a t i o n s y s t e m must be c a p a b l e of m a i n t a i n i n g a c r o s s t h e l o b b y d o o r d u r i n g a f i r e . The d e t e r m i n a t i o n of t h e d e s i g n p r e s s u r e d i f f e r e n c e i s beyond t h e s c o p e of t h i s paper and is t h e s u b j e c t of a n o t h e r i n v e s t i g a t i o n . T h i s p a p e r d e a l s o n l y w i t h t h e component of t h e d e s i g n p r e s s u r e d i f f e r e n c e caused by t h e t e m p e r a t u r e e f f e c t of f i r e . A c a l c u l a t i o n p r o c e d u r e was d e v e l o p e d t o a s s i s t i n d e s i g n i n g p r e s s u r e c o n t r o l s y s t e m s i n v o l v i n g e i t h e r v a r i a b l e s u p p l y a i r o r r e l i e f dampers i n t h e w a l l s of t h e e l e v a t o r s h a f t o r l o b b i e s . F i g u r e 4 shows t h e s c h e m a t i c drawings of both t h e e l e v a t o r s h a f t and t h e e l e v a t o r

I

lobby p r e s s u r i z a t i o n systems. The l e a k a g e a r e a s i n t h e w a l l s of t h e a i r f l o w s y s t e m s a r e

I

i n d i c a t e d i n t h e s e f i g u r e s . By c o n s i d e r i n g e q u a t i o n s f o r p a r a l l e l and series f l o w

c o m b i n a t i o n s d e s c r i b e d i n K l o t e and F o t h e r g i l l ( 1 9 8 3 ) , t h e r e q u i r e d s u p p l y a i r r a t e s f o r a

I

g i v e n d e s i g n p r e s s u r e d i f f e r e n c e , t h e r e s u l t a n t p r e s s u r e d i f f e r e n c e s when d o o r s a r e opened,

I

s h a f t and lobby p r e s s u r i z a t i o n systems a r e l i s t e d i n Appendix and t h e r e q u i r e d r e l i e f damper s i z e s c a n be c a l c u l a t e d . These e q u a t i o n s f o r b o t h t h e e l e v a t o r A. The b a s i c e q u a t i o n is

I

where

I

Q = s u p p l y a i r r a t e

C = c o n s t a n t f o r a s t a n d a r d a i r c o n d i t i o n

I

Ae = o v e r a l l e q u i v a l e n t l e a k a g e area from t h e p r e s s u r i z e d s p a c e t o o u t s i d e p e r f l o o r AP = p r e s s u r e d i f f e r e n c e from t h e p r e s s u r i z e d s p a c e t o o u t s i d e

The v a l u e s of Ae f o r t h e e l e v a t o r s h a f t and t h e e l e v a t o r l o b b y can be c a l c u l a t e d from

e q u a t i o n s i n Appendix A, s t e p 1. For a g i v e n d e s i g n 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 e l e v a t o r l o b b y d o o r (AP3), t h e r e q u i r e d AP can be c a l c u l a t e d from e q u a t i o n s i n Appendix A, s t e p 2 ,

which show t h a t AP,/AP i s c o n s t a n t f o r a g i v e n set of l e a k a g e a r e a s . The r e q u i r e d s u p p l y a i r r a t e s c a n be c a l z u i a t e d from e q u a t i o n s i n Appendix A, s t e p 3. F o r t h e open-door c o n f i g u r a t i o n w i t h t h e e l e v a t o r , e l e v a t o r l o b b y , and e x i t d o o r s on t h e ground f l o o r open s o t h a t t h e

e l e v a t o r s h a f t is d i r e c t l y exposed t o o u t s i d e p r e s s u r e , t h e f l o w r a t e on t h e ground f l o o r from t h e e l e v a t o r s h a f t t o o u t s i d e can be c a l c u l a t e d w i t h e q u a t i o n s i n Appendix A, s t e p 4. The t o t a l o u t s i d e s u p p l y a i r r a t e s r e q u i r e d t o p r e s s u r i z e t h e e l e v a t o r lobby t o a s p e c i f i e d d e s i g n l e v e l (AP $ can be c a l c u l a t e d using e q u a t i o n s i n Appendix A, s t e p 5 and s t e p 7, f o r t h e c a s e

wirh

all

ioors c l o s e d , QT, and with Lhe ground f l o o r d o o r s open, QT1, r e s p e c t i v e l y . The c a l c u l a t i o n of QT' c a n i n c l u d e open lobby d o o r s on o t h e r f l o o r s t o conform t o a g i v e n d e s i g n c r i t e r i a by u s i n g a s u i t a b l e v a l u e of Ae

on

t h o s e f l o o r s , as i n d i c a t e d i n t h e n o t e i n s t e p 1. For a v a r i a b l e s u p p l y a i r f a n g y s t e m w i t h f e e d b a c k c o n t r o l , t h e r a n g e of s u p p l y a i r r a t e

I

r e q u i r e d is t h e n g i v e n by QT and QT1.

With supply a i r , QT, set f o r t h e a l l - d o o r s - c l o s e d s i t u a t i o n , t h e lowered v a l u e of AP

'

caused by opening d o o r s on t h e ground f l o o r i s g i v e n by e q u a t i o n s i n Appendix A, s t e p 6 ,

aria,

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i c o r r e s p o n d i n g l y , w i t h s u p p l y a i r , Q T 1 , set f o r t h e open-door c o n d i t i o n , t h e i n c r e a s e d v a l u e of

AP3caused by c l o s i n g a l l d o o r s i s g i v e n by e q u a t i o n s i n s t e p 8. The v a l u e s of APjl and AP3

s h o u l d be checked, f o r i n t h e former c a s e , AP3' may be t o o low t o p r e v e n t smoke i n f i l t r a t i o n , 1 whereas f o r t h e l a t t e r c a s e , AP3 may be g r e a t enough t o c a u s e d i f f i c u l t y i n o p e n i n g lobby

doors. The problem of o v e r p r e s s u r i z a t i o n can be overcome by p r o v i d i n g r e l i e f dampers i n t h e w a l l s of e i t h e r t h e s h a f t o r l o b b y on e a c h f l o o r . The e q u a t i o n f o r t h e r e q u i r e d s i z e of r e l i e f damper i s g i v e n i n Appendix A, s t e p 9 , and t h e c o r r e s p o n d i n g r e q u i r e d s u p p l y a i r r a t e i n s t e p 10. A f a c t o r , L , t o a c c o u n t f o r t h e s p e c i f i e d i n c r e a s e i n AP3 is i n c o r p o r a t e d i n t h e e q u a t i o n i n s t e p 9 f o r s i z i n g t h e damper s o t h a t t h e rise i n AP3 when t h e e l e v a t o r d o o r i s

c l o s e d i s l i m i t e d t o p r e v e n t d i f f i c u l t y i n door o p e r a t i o n . The r e l i e f dampers a r e c l o s e d when I

t h e e l e v a t o r and l o b b y d o o r s a r e open and t h e y a r e f u l l y open when a l l d o o r s a r e c l o s e d . When an e l e v a t o r s h a f t is p r e s s u r i z e d t o a c h i e v e t h e r e q u i r e d p r e s s u r e d i f f e r e n c e a c r o s s a lobby d o o r on t h e f i r e f l o o r and an e l e v a t o r o r lobby d o o r on some o t h e r f l o o r opens, t h e amount of p r e s s u r i z a t i o n i s d e c r e a s e d due t o t h e i n c r e a s e i n t h e t o t a l l e a k a g e a r e a of t h e s h a f t . Assuming t h e t o t a l q u a n t i t y of p r e s s u r i z a t i o n a i r s u p p l i e d t o t h e smoke c o n t r o l s y s t e m

is c o n s t a n t , t h e r e l a t i o n s h i p between t h e p r e s s u r e d i f f e r e n c e and t h e l e a k a g e a r e a b e f o r e and a f t e r t h e d o o r is opened c a n be e x p r e s s e d a s

(

=

(3)

=

K

( 2 I i N = number of f l o o r s A = e f f e c t i v e l e a k a g e a r e a from e l e v a t o r s h a f t t o o u t s i d e p e r f l o o r e A. = l e a k a g e a r e a of an open e l e v a t o r door I Combining E q u a t i o n s 2, 3, and 4 g i v e s ( 5 ) For a s e l e c t e d v a l u e of AP2/AP1, AP2 i s above a minimum a c c e p t a b l e v a l u e when t h e e l e v a t o r door is opened i f

A

+--

-

(N-1)

>

9

Ae ( 6 )

For example, i f AP /AP

>

1 1 3 and t h e minimum a c c e p t a b l e v a l u e of AP = 0.05 i n of w a t e r (12.5

a

P a ) , Ae = 0.318 f t (0.0295 m2), and A. = 6.00 i t 2 (0.557 m2), t h e n AP2 is above t h e minimum a c c e p t a b l e v a l u e f o r a tower h i g h e r t h a n 24 s t o r i e s . T h i s is a l s o t h e c a s e f o r t h e l o - s t o r y t o w e r , i f t h e v a l u e of A, i s less t h a n 2.65 i t 2 (0.246 m2). The l e a k a g e a r e a , A,,, c a n be d e c r e a s e d by t i g h t e n i n g u p t h e c a r e n c l o s u r e and d e c r e a s i n g t h e c l e a r a n c e between t h e c a r and t h e d o o r s i d e of t h e s h a f t . For t h e s e c a s e s , no s p e c i a l p r o v i s i o n i s r e q u i r e d f o r p r e s s u r e c o n t r o l t o a c c o u n t f o r an open e l e v a t o r door. E q u a t i o n 6 i s , h e n c e , u s e f u l i n t h e d e s i g n of a n e l e v a t o r p r e s s u r i z a t i o n s y s t e m t o check w h e t h e r p r e s s u r e c o n t r o l i s needed. I f some lobby

2238 where

-

A = t o t a l l e a k a g e a r e a of t h e s h a f t S u b s c r i p t 1 = b e f o r e t h e e l e v a t o r door i s open 2 = a f t e r t h e e l e v a t o r d o o r i s open

The v a l u e of AP2 s h o u l d be e q u a l t o t h e d e s i g n p r e s s u r e d i f f e r e n c e t o p r e v e n t smoke i n f i l t r a t i o n i n t o t h e e l e v a t o r s h a f t . The l e a k a g e a r e a s A! and A2 c a n be d e f i n e d a s

A1 = NAe ( a l l d o o r s c l o s e d )

and as an example of a n open d o o r c o n d i t i o n

A2 = (N-l)Ae

+

A, ( e l e v a t o r , l o b b y , and e x i t d o o r s on t h e ground f l o o r open) ( 4 ) where

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doors a r e assumed t o be open, t h e n t h e average v a l u e of Ae f o r t h e tower should be used i n Equation 6.

The r e s u l t s of t h e example c a l c u l a t i o n f o r t h e tower following t h e procedure i n Appendix

A a r e given i n Appendix B.

TEST PROCEDURE

The leakage a r e a s of t h e tower were s e t t o s i m u l a t e those of a b u i l d i n g with average

a i r t i g h t n e s s e s and a f l o o r a r e a of 9,730 f t 2 (904 m2) o r seven t i m e s t h a t of t h e f l o o r a r e a of t h e experimental tower. The values of leakage a r e a s f o r t h e tower given i n Table 1 were estimated from measurements of o t h e r b u i l d i n g s conducted by Tamura and Shaw (1976, and 1978).

The i n i t i a l s e r i e s of t e s t s were coaducted with low and high f i r e temperature

c o n d i t i o n s , both following approximately t h e ASTM-El19 s t a n d a r d time-temperature curve up t o t h e maximum t e s t temperatures and held c o n s t a n t t h e r e a f t e r . For t h e low temperature f i r e , intended t o r e p r e s e n t a s p r i n k l e r e d f i r e , t h e maximum temperature was s e t a t 840 F (400°C). This temperature, which is probably much h i g h e r than expected i n a s p r i n k l e r e d f i r e , was d i c t a t e d by t h e minimum temperature a t which t h e t e s t gas burners could be operated. For t h e high temperature f i r e , t h e maximum f i r e temperature was s e t a t 1380

F

(750°C); f i v e minutes a f t e r i n i t i o n , t h e e a s t and west w a l l vents on t h e second f l o o r , each with an a r e a of 5 f t 2

5

(0.46 m ), were opened t o s i m u l a t e broken windows. It is r e a l i z e d t h a t a much h i g h e r

temperature can occur i n an a c t u a l f i r e , but t h e s e l e c t e d temperature l e v e l was considered t o

be adequate f o r t h e purpose of t h e t e s t s . The c o n t r o l temperature f o r t h e burners was measured 1.0 f t (0.3 m) below t h e c e i l i n g d i r e c t l y above t h e gas burners. The h e a t o u t p u t s were 0.92 and 2.8 x

lo6

Btu/h (0.27 and 0.82 MW) f o r t h e low and high temperature f i r e s , r e s p e c t i v e l y ; t h e corresponding o u t s i d e combustion a i r s u p p l i e s were 385 cfm (0.18 m3/s) and 740 cfm (0.35 m3/s). The test schedule was s e t t o monitor smoke migration d u r i n g t h e burn p e r i o d s and t h e performance of both t h e e l e v a t o r s h a f t and lobby p r e s s u r i z a t i o n systems with t h e e l e v a t o r door c l o s e d and open. The supply a i r f o r p r e s s u r i z a t i o n was i n j e c t e d a t t h e bottom of t h e e l e v a t o r s h a f t o r t h e bottom of t h e a i r d i s t r i b u t i o n s h a f t f o r lobby

p r e s s u r i z a t i o n . For t h e low and high temperature f i r e t e s t s , t h e e l e v a t o r l o b b i e s w e r e p r e s s u r i z e d t o 0.05 i n . o f water (12.5 Pa) and 0.10 i n of water (25.0 Pa), r e s p e c t i v e l y . For t h e s e t e s t s two e x t r a p r e s s u r e t a p s were placed 1.33 f t (0.40 m) and 6.33 f t (1.93 m) above t h e second f l o o r l e v e l i n t h e i n s u l a t e d p l a s t e r b o a r d lobby door and connected t o a p r e s s u r e t r a n s d u c e r whose o u t p u t w a s recorded on a continuous pen recorder. They complemented t h e e x i s t i n g p r e s s u r e t a p l o c a t e d 10.12 i t (3.08 m) above f l o o r l e v e l . An e x t r a g a s sampling tube was placed i n s i d e t h e second f l o o r lobby and connected t o an i n f r a r e d gas a n a l y z e r , whose output was a l s o recorded on a continuous pen recorder.

.

..

The f i r e t e s t s were conducted' of both an e l e v a t o r s h a f t p r e s s u r i z a t i o n system and an e l e v a t o r lobby p r e s s u r i z a t i o n system. Both systems were t e s t e d a g a i n s t low and high

temperature f i r e s . The p r e s s u r i z a t i o n system was a c t i v a t e d f o r 15 minutes, shutdown, and t h e n r e a c t i v a t e d 40 minutes a f t e r i g n i t i o n of t h e f i r e t o determine t h e p r e s s u r e d i f f e r e n c e s a c r o s s t h e lobby door due t o p r e s s u r i z a t i o n a l o n e , f i r e a l o n e , and both a c t i n g t o g e t h e r . The low temperature f i r e t e s t with lobby p r e s s u r i z a t i o n system was conducted w i t h t h e p r e s s u r i z a t i o n system a c t i v a t e d p r i o r t o i g n i t i n g t h e burners t o more c l o s e l y s i m u l a t e expected f i r e

s i t u a t i o n s . A t about 70 minutes a f t e r i g n i t i o n , t h e f i r s t f l o o r e l e v a t o r door, lobby door, and an e x t e r i o r door were opened t o study t h e e f f e c t of t h e r e s u l t i n g drop i n p r e s s u r i z a t i o n .

A s e r i e s of non-fire t e s t s were conducted t o v e r i f y t h e c a l c u l a t i o n procedures given i n Appendix A. The methods of p r e s s u r e c o n t r o l t e s t e d were f o r a v a r i a b l e supply a i r system and t h e use of r e l i e f dampers i n t h e w a l l s of t h e e l e v a t o r s h a f t on each floor.- With t h e e l e v a t o r door closed and open, 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 e l e v a t o r lobby w a l l was c o n t r o l l e d t o a minimum of 0.05 i n of water (12.5 Pa) t o prevent smoke i n f i l t r a t i o n due t o a low temperature f i r e and a maximum of 0.15 i n of water (37.5 P a ) , which is w e l l below t h e allowable l i m i t of 0.36 i n of water (90 Pa) f o r door operation. This l a t t e r l i m i t was based on t h e requirement of t h e National F i r e P r o t e c t i o n Association F i r e Safety Code (NFPA 1985) on t h e maximum allowable door opening f o r c e of 30 l b (133 N ) and assuming a door s i z e of 7 f t (2.13 m) by

3.33 f t (1.02 m) and a f o r c e of 11 l b (40 N) t o overcome t h e door closure.

The t e s t s were conducted with temperature d i f f e r e n c e s between t h e i n s i d e and o u t s i d e of

I _{l e s s than 10}_F _{(6OC) and wind speed of l e s s than 10 mph (16 kmlh).} _{T e s t s under non-fire} I

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c o n d i t i o n s t o v a l i d a t e t h e e q u a t i o n s i n Appendix A were conducted w i t h t h e o u t s i d e w a l l

l e a k a g e a r e a s f o r t h e f i r s t and second f l o o r s h a v i n g t h e same v a l u e s a s t h o s e of t h e r e m a i n i n g f l o o r s t o s i m p l i f y v a l i d a t i o n .

RESULTS AND DISCUSSIONS

Smoke M i g r a t i o n

A d e t a i l e d h a z a r d a n a l y s i s c o n s i d e r i n g t h e e f f e c t of h e a t f l u x , t o x i c g a s e s and smoke o b s c u r a t i o n i s beyond t h e s c o p e of t h i s paper. However, a s i m p l i f i e d approach t o t h e smoke o b s c u r a t i o n problem i s t a k e n assuming t h a t p a r t i c u l a t e c o n c e n t r a t i o n s from a s o l i d f u e l f i r e would be p r o p o r t i o n a l t o t h e ' m e a s u r e d C02 c o n c e n t r a t i o n s from t h e s e t e s t s . T h i s assumption i s p r o b a b l y c o n s e r v a t i v e i n t h a t smoke d e p o s i t i o n r e d u c e s p a r t i c u l a t e c o n c e n t r a t i o n .

The C02 c o n c e n t r a t i o n s i n t h e tower f o r t h e h i g h t e m p e r a t u r e f i r e t e s t s 45 minutes a f t e r i g n i t i o n and 15 m i n u t e s a f t e r e l e v a t o r s h a f t p r e s s u r i z a t i o n a t 0.10 i n of w a t e r ( 2 5 P a ) a r e g i v e n i n T a b l e 2 and s i m i l a r l y a f t e r lobby p r e s s u r i z a t i o n i n T a b l e 3. The C02 c o n c e n t r a t i o n s a r e e x p r e s s e d a s p e r c e n t a g e of t h e c o n c e n t r a t i o n i n t h e second f l o o r measured 1 f t (0.3 m) below t h e c e i l i n g i n t h e burn a r e a . From a c o n s i d e r a t i o n of smoke o b s c u r a t i o n , i t can be assumed t h a t an a r e a i s r e a s o n a b l y s a f e i f i t is n o t c o n t a m i n a t e d t o an e x t e n t g r e a t e r t h a n 1% of t h a t i n t h e v i c i n i t y of a f i r e a r e a (McGuire et a 1 1970). It i s s e e n t h a t w i t h o u t

mechanical p r e s s u r i z a t i o n , t h e C02 c o n c e n t r a t i o n s a r e w e l l above t h e 1% l e v e l i n a l m o s t a l l s p a c e s i n c l u d i n g t h e e l e v a t o r s h a f t and l o b b i e s . The h i g h e s t c o n c e n t r a t i o n , 70X, o c c u r r e d i n t h e second f l o o r e l e v a t o r lobby. The h i g h e s t C02 c o n c e n t r a t i o n s i n t h e v e r t i c a l s h a f t s o c c u r r e d i n t h e s e r v i c e s h a f t . Examination of t h e t e m p e r a t u r e r i s e i n t h e t o w e r , g i v e n i n T a b l e 4, shows t h a t among v e r t i c a l s h a f t s , t h e s e r v i c e s h a f t had by f a r t h e g r e a t e s t

t e m p e r a t u r e i n c r e a s e w i t h an a v e r a g e rise of 100 F (38OC). P r e s s u r e d i f f e r e n c e s i n t h e tower g i v e n i n T a b l e 5 show t h a t , a s e x p e c t e d , t h e g r e a t e s t p r e s s u r e d i f f e r e n c e s o c c u r r e d a c r o s s t h e w a l l s of t h e s e r v i c e s h a f t w i t h f l o w from t h e f l o o r s p a c e s i n t o t h e s e r v i c e s h a f t below t h e

f i f t h f l o o r and t h e r e v e r s e f l o w d i r e c t i o n above i t . A s i m i l a r f l o w p a t t e r n can be s e e n f o r t h e r e t u r n a i r s h a f t , but t h e p r e s s u r e d i f f e r e n c e s a r e munch lower t h a n t h o s e of t h e s e r v i c e s h a f t . It would a p p e a r t h a t t h e s e r v i c e s h a f t a c t e d a s a f l u e and was t h e main passageway f o r C02 t o m i g r a t e t o u p p e r f l o o r s , c a u s i n g a t e n d e n c y f o r C02 on t h e s e f l o o r s t o e n t e r t h e s t a i r and e l e v a t o r l o b b i e s .

A f t e r 15 m i n u t e s of e l e v a t o r s h a f t p r e s s u r i z a t i o n , as shown i n T a b l e 2 , t h e e l e v a t o r s h a f t w a s c l e a r e d of C02 b u t t h e l e v e l s of C02 i n t h e e l e v a t o r l o b b i e s were s t i l l above t h e c r i t i c a l l e v e l . S i m i l a r l y , as shown i n T a b l e 3, when t h e lobby p r e s s u r i z a t i o n was a c t i v a t e d , t h e l o b b i e s were c l e a r e d of C02 b u t c o n c e n t r a t i o n s of C02 i n t h e e l e v a t o r s h a f t were above t h e c r i t i c a l l e v e l . A low t e m p e r a t u r e f i r e t e s t w i t h t h e lobby p r e s s u r i z a t i o n s y s t e m a c t i v a t e d p r i o r t o i g n i t i o n was s u c c e s s f u l i n k e e p i n g t h e e l e v a t o r s h a f t and l o b b i e s smoke f r e e a s l o n g a s a l l d o o r s were k e p t c l o s e d . These r e s u l t s i n d i c a t e t h a t i t i s i m p o r t a n t t o a c t i v a t e t h e p r e s s u r i z a t i o n s y s t e m b e f o r e t h e e l e v a t o r s h a f t and l o b b i e s a r e h e a v i l y c o n t a m i n a t e d w i t h smoke. T a b l e s 2 and 3 a l s o show t h a t , as e x p e c t e d , C02 c o n c e n t r a t i o n s i n t h e u n p r e s s u r i z e d s t a i r w e l l i n c r e a s e d when t h e e l e v a t o r p r e s s u r i z a t i o n s y s t e m s were a c t i v a t e d .

Temperature, P r e s s u r e D i f f e r e n c e , and CO, C o n c e n t r a t i o n of t h e Second F l o o r Lobby Due t o F i r e T a b l e s 6 and 7 g i v e t h e t e m p e r a t u r e s i n s i d e and o u t s i d e t h e s e c o n d f l o o r e l e v a t o r l o b b y , t h e p r e s s u r e d i f f e r e n c e s a c r o s s t h e l o b b y w a l l , and t h e C02 c o n c e n t r a t i o n s i n s i d e t h e lobby. They show t h a t when t h e b u r n e r s a r e o p e r a t i n g , t h e e l e v a t o r lobby t e m p e r a t u r e s a r e w e l l above t h e d a n g e r l e v e l f o r human e x p o s u r e . The two w a l l s of t h e l o b b y t h a t a r e exposed t o t h e burn a r e a a r e c o n s t r u c t e d of a l a y e r of 518 i n ( 1 6 mm) t h i c k gypsum w a l l b o a r d on e i t h e r s i d e of m e t a l s t u d s . With t h e p r e s s u r i z a t i o n s y s t e m o n , t h e l o b b y t e m p e r a t u r e s were lowered t o a b o u t 90-100 F (33-37OC) f o r t h e low t e m p e r a t u r e f i r e a n d t o a b o u t 125-145 F (52-63OC) f o r t h e h i g h t e m p e r a t u r e f i r e . For t h e c a s e when t h e s h a f t p r e s s u r i z a t i o n was a c t i v a t e d b e f o r e t h e burn p e r i o d , t h e lobby t e m p e r a t u r e f o r a low t e m p e r a t u r e f i r e was 98 F (37OC).

Examination of t h e r e s u l t a n t p r e s s u r e d i f f e r e n c e s a c r o s s t h e e l e v a t o r lobby w a l l i n d i c a t e d t h a t t h e y were a b o u t 20% and 40% g r e a t e r t h a n t h e a l g e b r a i c sum of t h e p r e s s u r e d i f f e r e n c e due t o p r e s s u r i z a t i o n and t e m p e r a t u r e e f f e c t of f i r e f o r t h e low and high

t e m p e r a t l i r e f i r e s , r e s p e c t i v e l y . The g r e a t e r v a l u e f o r t h e h i g h t e m p e r a t u r e t h a n f o r t h e low t e m p e r a t u r e f i r e may be a t t r i b u t e d t o t h e f i r e f l o o r b e i n g v e n t e d t o t h e o u t s i d e f o r t h e

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former case, r e s u l t i n g i n somewhat h i g h e r p r e s s u r e d i f f e r e n c e s on f l o o r s above and below t h e

f i r e f l o o r . It would appear t h a t an amount of p r e s s u r i z a t i o n e q u a l t o t h e adverse p r e s s u r e

d i f f e r e n c e due t o f i r e w i l l l i k e l y be more than adequate t o prevent smoke migration i n t o t h e

e l e v a t o r lobby.

Figure 5 shows t h e pressure d i f f e r e n c e p r o f i l e a c r o s s t h e lobby w a l l f o r both t h e low

and high temperature f i r e s . For t h e low temperature f i r e , t h e n e u t r a l p r e s s u r e l e v e l (NPL)

is

l o c a t e d a t about t h e 5.5 f t (1.6 m) l e v e l and f o r t h e high temperature f i r e a t t h e 3.2 f t

(0.9 m) l e v e l . The l o c a t i o n of NPL depends on both t h e d i s t r i b u t i o n of leakage openings on

t h e f i r e f l o o r and t h e gas temperatures. The lower NPL f o r t h e high temperature f i r e i s due

t o t h e lower gas d e n s i t y o u t s i d e t h e e l e v a t o r lobby t h a n f o r t h e low temperature f i r e . The

maximum adverse pressure d i f f e r e n c e s of 0.026 i n of water (6.5 Pa) and 0.030 i n of water (7.5 Pa) f o r t h e low and high temperature f i r e s , r e s p e c t i v e l y , occurred near t h e c e i l i n g l e v e l of

t h e lobby wall. When t h e mechanical p r e s s u r i z a t i o n was a c t i v a t e d , t h e p r e s s u r e p r o f i l e

s h i f t e d t o t h e r i g h t t o show p o s i t i v e p r e s s u r i z a t i o n f o r t h e f u l l h e i g h t of t h e lobby, but

when t h e e l e v a t o r , lobby, and e x i t doors on t h e ground f l o o r were opened, i t s h i f t e d t o t h e

l e f t t o underpressurize t h e upper w a l l s of t h e lobby.

The v a r i a t i o n of lobby temperature, p r e s s u r e d i f f e r e n c e , and C02 c o n c e n t r a t i o n during

t h e bum, p r e s s u r i z a t i o n , and open door periods a r e g r a p h i c a l l y i l l u s t r a t e d i n Figure 6. The

time-lobby pressure d i f f e r e n c e curve shows t h a t soon a f t e r i g n i t i o n of t h e b u r n e r s , t h e r e is a sudden momentary i n c r e a s e i n adverse p r e s s u r e d i f f e r e n c e , probably caused by t h e rapid thermal expansion of gases t o 0.05 i n of water (12.5 Pa) with a s p i k e of 0.085 i n of water (21 Pa) and

a decrease t o a s t e a d y v a l u e a s t h e burn a r e a reached t h e c o n t r o l f i r e temperature. For t h e

low temperature f i r e , thermal expansion caused a maximum p r e s s u r e d i f f e r e n c e of 0.06 i n of

water (15 Pa) with a s p i k e of 0.10 i n of water (25 Pa). A h i g h e r thermal expansion e f f e c t

occurred with t h e low as compared t o t h e high temperature f i r e , probably because f o r t h e former, only one burner s t r i p was used, whereas f o r t h e l a t t e r , t h r e e burner s t r i p s were

i g n i t e d i n sequence. Pressure d i f f e r e n c e s due t o thermal expansion, which were of s h o r t

d u r a t i o n , d i d not cause s i g n i f i c a n t c o n c e n t r a t i o n of C02 i n t h e e l e v a t o r lobby i n t h e c a s e of t h e low temperature f i r e with t h e lobby d i r e c t l y p r e s s u r i z e d t o 0.05 i n of water (12.5 Pa)

p r i o r t o i g n i t i n g t h e burner. The supply a i r f o r p r e s s u r i z a t i o n probably d i l u t e d smoke t h a t

might have i n f i l t r a t e d t h e lobby.

Examination of C02 c o n c e n t r a t i o n s i n t h e e l e v a t o r lobby, a s given i n Tables 6 and 7, shows t h a t t h e C02 c o n c e n t r a t i o n s were reduced s i g n i f i c a n t l y with s h a f t p r e s s u r i z a t i o n ( s e e a l s o Figure 6) and reduced t o t h e background l e v e l with lobby p r e s s u r i z a t i o n , but C02 l e v e l s i n t h e lobby and e l e v a t o r s h a f t increased f o r both t h e s h a f t and lobby p r e s s u r i z a t i o n when t h e doors on t h e ground f l o o r were opened.

Comparison of Calcul.ated and Experimental R e s u l t s

The r e s u l t s of t h e t e s t s conducted t o check t h e equations i n Appendix A, developed f o r t h e

design of p r e s s u r i z a t i o n systems with p r e s s u r e c o n t r o l , a r e summarized i n Table 8. For both

t h e v a r i a b l e supply a i r and r e l i e f dampers f o r p r e s s u r e c o n t r o l , t h e measured and c a l c u l a t e d

values of supply a i r r a t e s and p r e s s u r e d i f f e r e n c e s agreed w e l l w i t h i n 10% of each o t h e r . To

f a c i l i t a t e comparison of t h e c a l c u l a t e d and t h e measured v a l u e s , t h e supply a i r r a t e f o r e l e v a t o r p r e s s u r i z a t i o n was kept c o n s t a n t with c l o s i n g o r opening of t h e doors on t h e ground

f l o o r . I n p r a c t i c e , t h e supply a i r r a t e , according t o t h e f a n c h a r a c t e r i s t i c , would decrease

with t h e c l o s i n g of doors due t o t h e i n c r e a s e i n t h e system's flow r e s i s t a n c e , and t h e o p p o s i t e would occur with t h e opening of doors; hence, assuming a c o n s t a n t supply a i r r a t e would give conservative v a l u e s of 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 e l e v a t o r lobby wall.

The leakage openings a t t h e t o p of t h e e l e v a t o r s h a f t were not considered i n t h e

c a l c u l a t i o n . Measurements by Tamura and Shaw (1976), i n s e v e r a l b u i l d i n g s i n d i c a t e d t h a t they

v a r i e d from 4 t o 10 f t 2 (0.37 t o 0.93 m2), except f o r one case of 0.50 f t 2 (0.046 m2) i n which

openings i n t h e c o n c r e t e f l o o r s l a b of t h e machine room were p a r t l y covered with sheet metal. The leakage openings a t t h e t o p of a p r e s s u r i z e d e l e v a t o r s h a f t should be minimized o r taken

i n t o account i n t h e c a l c u l a t i o n of supply a i r r a t e s and s i z e of r e l i e f dampers. Using t h e

equation i n Appendix A, s t e p 4, f o r an open e l e v a t o r door with A. replaced by t h e leakage a r e a

a t t h e t o p of an e l e v a t e d s h a f t w i l l g i v e c o n s e r v a t i v e values.

E l e v a t o r , Lobby, and E x i t Doors

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lobby, and e x i t doors open on t h e ground f l o o r . For t h e case of a v a r i a b l e a i r supply p r e s s u r i z a t i o n system, 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 e l e v a t o r lobby was intended t o be c o n t r o l l e d t o 0.05 i n . of water (12.5 Pa) f o r a low temperature f i r e . The required supply a i r r a t e f o r e l e v a t o r s h a f t p r e s s u r i z a t i o n ranged from 2000 t o 5590 cfm (0.944 t o 2.64 m3/s); i f t h e lobby doors on a l l f l o o r s except t h e f i r e f l o o r were a l s o assumed t o be open, t h e required maximum supply a i r r a t e would have been 5950 cfm (2.82 m3/s). For t h e case of a

p r e s s u r i z a t i o n system with r e l i e f dampers t o maintain t h e same p r e s s u r e d i f f e r e n c e a s i n t h e case with t h e ground f l o o r doors open, but t o 0.15 i n of water (37.5 Pa) with a l l doors

c l o s e d , t h e required s i z e s of dampers were 0.21 f t 2 (0.020 m2) and 0.11 f t 2 (0.011 m2) f o r t h e e l e v a t o r s h a f t and lobby p r e s s u r i z a t i o n systems, r e s p e c t i v e l y . To maintain t h e p r e s s u r e d i f f e r e n c e a t 0.05 i n of water (12.5 Pa) with a l l doors c l o s e d , l a r g e r s i z e r e l i e f dampers would be r e q u i r e d , and they can be c a l c u l a t e d u s i n g equations i n Appendix A, s t e p 9, with L = 1.0. For t h i s c a s e , t h e required s i z e s of damper i n t h e s h a f t w a l l s would be 0.62 f t 2 (0.057 m2) and 0.67 f t 2 (0.063 m2) f o r t h e s h a f t and lobby p r e s s u r i z a t i o n systems,

r e s p e c t i v e l y . Furthermore, i f t h e lobby doors on a l l f l o o r s except t h e f i r e f l o o r were assumed a l s o t o be open, t h e required damper s i z e s would be 0.68 f t 2 (0.063 m2) i n t h e s h a f t wall f o r t h e s h a f t p r e s s u r i z a t i o n system.

CONCLUSIONS

1. F i r e t e s t s conducted i n t h e experimental f i r e tower i n d i c a t e d t h a t t h e tower was completely contaminated w i t h smoke (C02 a s i n d i c a t o r ) due t o e f f e c t of t h e f i r e

temperature alone. The e l e v a t o r s h a f t p r e s s u r i z a t i o n system was e f f e c t i v e i n c l e a r i n g smoke i n t h e s h a f t i n a s h o r t time, but r e s i d u a l smoke with c o n c e n t r a t i o n s above t h e c r i t i c a l l e v e l remained i n t h e l o b b i e s , and, s i m i l a r l y , t h e e l e v a t o r lobby p r e s s u r i z a t i o n system was e f f e c t i v e i n c l e a r i n g smoke i n t h e l o b b i e s i n a s h o r t time, but r e s i d u a l smoke

1

remained i n t h e s h a f t f o r some time. It is important t o a c t i v a t e t h e p r e s s u r i z a t i o n

I systems b e f o r e t h e e l e v a t o r s h a f t , and l o b b i e s a r e h e a v i l y contaminated w i t h smoke.

2. Examination of t h e p r e s s u r e d i f f e r e n c e s due t o mechanical p r e s s u r i z a t i o n and those due t o I

t h e f i r e i n d i c a t e d t h a t an amount of p r e s s u r i z a t i o n e q u a l t o t h e adverse p r e s s u r e d i f f e r e n c e caused by t h e f i r e w i l l l i k e l y be more than adequate t o prevent smoke

I migration i n t o e l e v a t o r lobbies. Test r e s u l t s i n d i c a t e d t h a t a t s t e a d y f i r e temperature,

maximum adverse p r e s s u r e d i f f e r e n c e s due t o t h e thermal e f f e c t of f i r e occurred a c r o s s t h e e l e v a t o r lobby w a l l a t t h e c e i l i n g l e v e l of about 0.026 i n of water (6.2 Pa) f o r t h e low temperature f i r e and 0.03 i n of water (7.5 Pa) f o r t h e high temperature f i r e . Those due t o thermal expansion soon a f t e r i g n i t i o n were much h i g h e r but of s h o r t d u r a t i o n . It is l i k e l y t h a t a p r e s s u r i z a t i o n a c r o s s t h e e l e v a t o r lobby w a l l of 0.05 i n of water (12.5 Pa) and 0.10 i n of water (25 Pa) would be s u f f i c i e n t f o r low and high temperature f i r e s r e s p e c t i v e l y . Adverse p r e s s u r e d i f f e r e n c e s caused by o t h e r mechanisms, however, should a l s o be considered i n t h e design.

3. Opening e l e v a t o r , lobby, and e x i t doors on t h e ground f l o o r caused a r e d u c t i o n i n

p r e s s u r i z a t i o n r e s u l t i n g i n t h e contamination of t h e e l e v a t o r s h a f t and lobby on t h e f i r e f l o o r . To cope with open door s i t u a t i o n s , e q u a t i o n s were developed t o permit t h e d e s i g n of p r e s s u r i z a t i o n systems with v a r i a b l e supply a i r w i t h feedback c o n t r o l and a l s o w i t h r e l i e f dampers. These e q u a t i o n s gave r e s u l t s t h a t were w e l l w i t h i n 10% of t h e measured values i n t h e experimental f i r e tower. It should be emphasized, however, t h a t t o design an e f f e c t i v e p r e s s u r i z a t i o n system r e q u i r e s a knowledge and c o n t r o l of t h e a i r leakage c h a r a c t e r i s t i c s of t h e b u i l d i n g and, i n p a r t i c u l a r , t h o s e of t h e e l e v a t o r s h a f t and lobbies.

REFERENCES

Achakji, G.Y. 1987. "NRCC experimental f i r e tower f o r s t u d i e s on smoke movement and c o n t r o l i n t a l l buildings." I n s t i t u t e f o r Research i n Construction, National Research Council of Canada, I n t e r n a l Report No. 512.

ASHRAE. 1985. ASHRAE handbook

-

1985 fundamentals, p. 22.4 Atlanta: American S o c i e t y of Heating, R e f r i g e r a t i n g , and Air-Conditioning Engineers, Inc.

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Klote, J.H. 1983. "Elevators as a means of f i r e escape." V.89, Pt. 1.

Klote, J.H., and Tamura, G.T. 1986. "Smoke c o n t r o l and f i r e evacuation by e l e v a t o r s . " ASHRAE Transactions V.92, Pt.1.

Klote, J.H., and F o t h e r g i l l , J.W. Jr. 1983. "Design of smoke c o n t r o l systems f o r buildings." Atlanta: American Society of Heating, R e f r i g e r a t i n g , and Air-Conditioning Engineers, Inc.

McGuire, J.H., Tamura, G.T., and Wilson, A.G. 1970. "Factors i n c o n t r o l l i n g smoke i n . high buildings.'? Proceedings, Symposium on F i r e Hazards i n Buildings, ASHRAE, pp. 8-13.

Tamura, G.T., and Shaw, C.Y. 1976. "Air leakage d a t a f o r t h e design of e l e v a t o r and s t a i r s h a f t p r e s s u r i z a t i o n systems-." ASHRAE Transaction, Vol. 82, p a r t 2, pp. 179-190.

Tamura, G.T., and Shaw, C.Y. 1978. "Experimental s t u d i e s of mechanical v e n t i n g f o r smoke c o n t r o l i n t a l l o f f i c e buildings." ASHRAE T r a n s a c t i o n s , Vol. 84, p a r t 1, pp. 54-71.

ACKNOWLEDGEMENT

The a u t h o r s g r a t e f u l l y acknowledge t h e c o n t r i b u t i o n of R.A. MacDonald i n s e t t i n g up and conducting t h e t e s t s i n t h e experimental f i r e tower and p r o c e s s i n g t h e test r e s u l t s ; of

J.E. Berndt i n running t h e d a t a a c q u i s i t i o n and c o n t r o l system and t h e gas burner system, and f o r preparing software f o r d a t a r e d u c t i o n ; and of o t h e r s t a f f members of t h e National F i r e Laboratory i n a s s i s t i n g d u r i n g t h e p r e p a r a t i o n and conduct of t h e t e s t s .

APPENDIX A

I

C a l c u l a t i o n of P r e s s u r e s , Flow Rates, and Vent S i z e s

I

I _{The following e q u a t i o n s were d e r i v e d f o r t h e e l e v a t o r s h a f t and lobby p r e s s u r i z a t i o n} I systems, which a r e i l l u s t r a t e d i n Figures 4a and 4b, r e s p e c t i v e l y , by applying t h e equations

I f o r p a r a l l e l / s e r i e s flow and a i r f l o w through leakage openings, which a r e given i n (Klote and

I

F o t h e r g i l l 1983).

P r e s s u r i z e d E l e v a t o r S h a f t

1. Ae, o v e r a l l e q u i v a l e n t

(

A1+ '23e "4 leakage a r e a from t h e

_[(*I+

_A23e p r e s s u r i z e d space t o

o u t s i d e

-

where

P r e s s u r i z e d Lobbies

where

note: with lobby door open

-

note: with lobby door

(A3

>>

A2) open

A3 = leakage a r e a due t o door opening.

V e r t i c a l flow i n s h a f t assumed t o be n e g l i g i b l e .

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2. AP, o v e r a l l p r e s s u r e d i f f e r e n c e from t h e p r e s s u r i z e d s p a c e t o o u t s i d e 3. Q _f

,

p r e s s u r i z a t i o n flow r a t e p e r f l o o r 4 - Qo, f l o w r a t e a t ground f l o o r through open e l e v a t o r door w i t h lobby and e n t r a n c e d o o r s a l s o open 5. QT, t o t a l r e q u i r e d p r e s s u r i z a t i o n f l o w r a t e f o r a g i v e n AP w i t h a l l 3 doors on ground f l o o r of S t e p 4 c l o s e d where 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 t h e e l e v a t o r 3 lobby door where

-

M = AP3/AF' ( S e e S t e p 2) For a i r a t s t a n d a r d c o n d i t i o n

C

= 2400 w i t h Q ( c f m ) , Ae ( f t 2 ) , U 3 ( i n of w a t e r )

c

= 772 w i t h Q ( g / s ) , Ae (m2), @ 3 ( P a ) where A = l e a k a g e a r e a of 0 an open e l e v a t o r door N = t o t a l number of f l o o r s 6 . AP31; QT w i t h ground f l o o r e l e v a t o r , lobby, and e n t r a n c e doors open 7. Q T t , t o t a l r e q u i r e d (N-l)Qf + Qo f l o w r a t e f o r a g i v e n AP w i t h ground f l o o r 3 e l e v a t o r , lobby and e n t r a n c e doors open

(15)

2

8. AP3 ; QT1 with a l l doors closed

S h a f t wall S h a f t wall

9. A d , required s i z e of A1' =

-

*23e

[

QT' QT'

C N ( L A P ~ )

t J -

A23e = CN(LAPJ

f

-

A3 r e l i e f damper f o r each f l o o r i n t h e w a l l of t h e e l e v a t o r shaf t/lobby f o r a f a c t o r L where L = allowable f a c t o r f o r i n c r e a s e i n AP when 3 open doors on ground f l o o r a r e closed 10. QdT, required t o t a l QT' supply a i r r a t e with r e l i e f dampers Ad = A l t

-

A 1 Lobby w a l l APPENDIX B

P r e s s u r e s , Flow Rates, and Vent S i z e s f o r t h e 10-Story Experimental F i r e Tower

Leakage Areas A 1 = 0.07 ft2(0.006 m2); A 2 ( e l e v a t o r door c l o s e d ) = 0.75 ft2(0.070 m2); A2 ( e l e v a t o r door open) = 6.00 f t2(0.557 m) ; A3 = 0.30 ft2(0.028 m2); A4 = 0.79 ft2(0.073 m2)

(16)

P r e s s u r i z e d E l e v a t o r S h a f t 1. Ae ( p e r s t o r y ) 0.318 f t 2 (0.0295 m2) 1.39 AP3 900 (AP3) cfm 26.4 (dp3)+

11s

+

16980 (AP3) cfm 507 ( A P ~ ) + i/s

+

9000 (AP3) cfm 264 (AP3)+ i/s 0.13 AP3 25000 ( A P ~ ) ' c f o 745 (AP3)+

11.

7.7 APg 0.335 f t 2 , (0.0311 m2) 1.22 AP3 888 (AP3) cfm 26.0 (AP3)'

11s

11900 (AP3)+ cfm 355 ( A P ~ ) + L l s 8880 (AP3)+ cfm 265 ( AP3)+

Ys

0.20 AP3 19900 (AP3)' cfm 590 ( AP3)'

V s

5.0 AP3 S h a f t w a l l Lobby w a l l 0.21 f t 2 (0.020 m2) 0.11 f t 2 (0.010 m2) same a s 7 S h a f t w a l l 0.11 f t 2 (0.010 m2) same a s 7

(17)

TABLE 1

Leakage Flow Areas per Floor of t h e Experimental F i r e Tower

Location

-

Area Outside w a l l s 1 s t f l o o r e a s t w a l l 1 s t f l o o r west wall 2nd f l o o r e a s t w a l l (wall 2nd f l o o r e a s t w a l l ( w a l l 2nd f l o o r west w a l l (wall 2nd f l o o r west wall ( w a l l Typical f l o o r e a s t w a l l Typical f l o o r west w a l l vent c l o s e d ) vent open) vent c l o s e d ) vent open) E l e v a t o r Floor space t o e l e v a t o r s h a f t 0.07 0.006

Floor space t o e l e v a t o r lobby (lobby door closed) 0.30 0.028 Floor space t o e l e v a t o r lobby (lobby door open) 21.00 1.951 Elevator lobby t o e l e v a t o r s h a f t ( e l e v a t o r doors c l o s e d ) 0.75 0.070 Elevator lobby t o e l e v a t o r s h a f t ( e l e v a t o r doors open) 6.00 0.557 S t a i r s

Floor space t o s t a i r s h a f t

Floor space t o s t a i r lobby (lobby door closed) Floor space t o s t a i r lobby (lobby door open) S t a i r lobby t o s t a i r s h a f t ( s t a i r door closed) S t a i r lobby t o s t a i r s h a f t ( s t a i r door open) V e r t i c a l S h a f t s

Floor space t o s e r v i c e s h a f t Floor space t o supply a i r s h a f t * Floor space t o r e t u r n a i r s h a f t * C e i l i n g

(18)

TABLE 2

C0 Concent r a t i o n s w i t h High Temperature F i r e

-

E l e v a t o r S h a f t P r e s s u r i z a t i o n

Unbracketed numbers

-

45 min. a f t e r i g n i t i o n and w i t h o u t p r e s s u r i z a t i o n Bracketed numbers

-

15 min. a f t e r p r e s s u r i z a t i o n system i s a c t i v a t e d

Cog c o n c e n t r a t i o n , X of c o n c e n t r a t i o n i n t h e f i r e r e g i o n Burn E l e v a t o r E l e v a t o r S t a i r S t a i r S e r v i c e F l o o r a r e a lobby S h a f t lobby s h a f t s h a f t TABLE 3 C02 C o n c e n t r a t i o n s w i t h High Temperature F i r e

-

E l e v a t o r Lobby P r e s s u r i z a t i o n

Unbracketed numbers

-

30 min. a f t e r i g n i t i o n and w i t h o u t p r e s . s u r i z a t i o n Bracketed numbers

-

15 min. a f t e r p r e s s u r i z a t i o n system

i s

a c t i v a t e d

C02 c o n c e n t r a t i o n , X of c o n c e n t r a t i o n i n t h e f i r e r e g i o n F l o o r 10 9 8 7 6

5

4 3 2 1 Burn a r e a E l e v a t o r lobby E l e v a t o r S t a i r S h a f t lobby S t a i r S e r v i c e s h a f t s h a f t

(19)

TABLE 4

Temperature R i s e i n t h e Tower 30 Minutes A f t e r I g n i t i o n During a High Temperature F i r e T e s t

O u t s i d e t e m p e r a t u r e 45 F (7OC)

Burn E l e v a t o r E l e v a t o r S t a i r S t a i r S e r v i c e F l o o r a r e a lobby S h a f t lobby s h a f t s h a f t

F (OC) F (OC) F (OC) F (OC)

F

(OC) F (OC)

TABLE 5

P r e s s u r e D i f f e r e n c e s i n t h e Tower 30 M i n u t e s A f t e r I g n i t i o n During a High Temperature F i r e T e s t

P r e s s u r e d i f f e r e n c e

-

i n of w a t e r ( P a ) R e f e r e n c e p r e s s u r e

-

burn a r e a F l o o r 10 9 8 7 6

5

4

3 2 1 -- - S t a i r lobby - - R e t u r n A i r s h a f t S e r v i c e s h a f t E l e v a t o r lobby

(20)

TABLE

6

R e s u l t s of F i r e T e s t s w i t h E l e v a t o r S h a f t P r e s s u r i z a t i o n E l e v a t o r lobby on f i r e f l o o r (2nd f l o o r ) Temperature AP lobby w a l l C02 o u t s i d e i n s i d e i n . of w a t e r ( P a ) lobby lobby

1.33

f t

6.33

f t

10.12

f t % a b s o l u t e F(

OC)

F(

OC)

(0.40

m)

(1.93

m)

(3.08

m) r e f e r e n c e p r e s s u r e

-

burn a r e a Low Temp. F i r e P r e s s u r i z a t i o n

-

0.046 (11.5)

0.048 (11.9)

Burn

-

30

min.

760 (405) 153 (67)

0.026 (6.5)

-0.004

(-1)

-0.026 (-6.5)

2.20

Burn

+

P r e s s .

673 (356) 91 (33)

0.081 (20.2)

0.051 (12.7)

0.017 (4.2)

0.12 -

15

min. Burn

+

P r e s s .

716 (380) 116 (47)

0.055 (13.7)

0.010 (2.5)

-0.019(-4.7)

0.20

& open d o o r s on ground f l o o r

-

15

min. High Temp. F i r e

1380

F

(750°C)

P r e s s u r i z a t i o n

-

0.102 (25.4)

0.100 (24.9)

0.098 (24.4)

-

Burn

-

30

min.

1243 (673) 460 (238) 0.006 (1.5)

-0.018 (-4.5)

-0.030 (-7.5)

2.94

Bum

+

P r e s s .

1070 (576) 145 (63)

0.140 (34.9)

0.100 (24.9)

0.094 (23.4)

0.25 -

15

min. Bum

+

P r e s s .

1217 (630) 159 (87)

0.030 (7.5)

0.101 (2.5)

-0.010 (-2.5)

0.75

& open d o o r s on ground f l o o r

-

15

min.