Design Considerations for Toxic Laboratories - American Chemical

Chapter 15

Design Considerations for Toxic Laboratories William J. Maurits

Downloaded by NATL UNIV OF SINGAPORE on May 6, 2018 | https://pubs.acs.org Publication Date: July 20, 1987 | doi: 10.1021/bk-1987-0345.ch015

Department of Army, Aberdeen Proving Ground, MD 21010-5423

Those elements of conventional laboratory design that must be refined for facilities in which toxic chemicals will be handled are presented. Alarms, communications, construction materials, containment cabinets, filter systems, floor plans, security, compressed gases, and waste disposal are discussed. Emphasis is given to design considerations dictated by the use of large numbers of fume hoods.

A successful designer of a t o x i c l a b o r a t o r y w i l l f i n d i t necessary t o r e f i n e most o f the elements o f the t r a d i t i o n a l c h e m i c a l l a b o r a tory. Many d e t a i l s which a r e n ' t d i r e c t l y a s s o c i a t e d w i t h the t o x i c o p e r a t i o n s w i l l impact on the s a f e t y o f these o p e r a t i o n s . Because common l a b o r a t o r y mishaps w i l l be f a r more s e r i o u s where t o x i c s are used, i t makes sense t o i n v e s t e v e r y e f f o r t to p r e c l u d e such a c c i dents through c a r e f u l d e s i g n . Floor

Plan

The flow of personnel i n and out o f t o x i c areas can spread c o n t a m i n a t i o n , so the l a y o u t o f a l a b o r a t o r y s h o u l d f a c i l i t a t e r o u t i n e movement o f workers as w e l l as emergency e v a c u a t i o n s . S t a f f s h o u l d not have to walk through one l a b o r a t o r y t o get to another nor s h o u l d an o f f i c e be l o c a t e d where the o n l y e x i t i s through a l a b o r a t o r y . The p r o v i s i o n o f s e p a r a t e a d m i n i s t r a t i v e areas w i l l a v o i d l o c a t i n g s c i e n t i s t ' s desks i n rooms where t o x i c s are used. V i s i t o r s are s a f e r and more e a s i l y s u f f e r e d i f they can view the l a b o r a t o r y rooms through windows. L a b o r a t o r y a i s l e s must be no l e s s than 5 f e e t wide and benches s h o u l d have s u f f i c i e n t u n o b s t r u c t e d w i d t h t o accommodate modern a n a l y t i c a l i n s t r u m e n t a t i o n . An overhead ( f i l t e r e d ) exhaust system would p e r m i t s m a l l canopy hoods t o be connected as n e c e s s a r y to scavenge fumes from areas near i n j e c t i o n and exhaust p o r t s o f anal y z e r s not l o c a t e d i n hoods. Each room s h o u l d have i t s own s u p p l y

This chapter not subject to US. copyright Published 1987 American Chemical Society

Scott and Doemeny; Design Considerations for Toxic Chemical and Explosives Facilities ACS Symposium Series; American Chemical Society: Washington, DC, 1987.


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of a i r f o r v e n t i l a t i o n . S e l f c l o s i n g doors w i l l h e l p m a i n t a i n required s t a t i c pressure d i f f e r e n t i a l s . Emergency s t a t i o n s s h o u l d be l o c a t e d near e x i t s and s h o u l d i n c l u d e emergency shower ( w i t h d r a i n ) , and s t o r a g e f o r b l a n k e t s , t o w e l s , soap and l i g h t c l o t h i n g . Eyewashes must be a v a i l a b l e i n each l a b o r a t o r y , and s h o u l d f e a t u r e p o s i t i v e temperature c o n t r o l , s i n c e i t i s i m p o s s i b l e to wash ones eyes f o r 15 minutes i n i c y water. Alarm p u l l boxes s h o u l d be near each door f o r c o n v e n i e n t use on the way o u t . Each l a b o r a t o r y or storeroom s h o u l d have two e x i t s ( w i t h doors t h a t swing o u t ) p l a c e d so t h a t no c r e d i b l e event can b l o c k emergency e g r e s s . Workers must be assured an unimpeded path out o f the b u i l d i n g i n the event o f e m e r g e n c i e s , so i t i s i n a p p r o p r i a t e t o secure b u i l d i n g doors w i t h l o c k s t h a t cannot be opened from the i n s i d e . Any p e r i m e t e r f e n c i n g s h o u l d i n c l u d e gates w i t h l o c k s t h a t can be opened from the i n s i d e . L a b o r a t o r y rooms i n t e n d e d f o r t o x i c work s h o u l d be p r o v i d e d w i t h adjacent shower and change f a c i l i t i e s . The l a y o u t must not r e q u i r e f r e s h l y showered personnel to t r a c k back through the area t h a t they might have j u s t c o n t a m i n a t e d . A l l drains, including those i n l a b o r a t o r y f l o o r s , s h o u l d have deep t r a p s and be d i r e c t e d t o a t o x i c sump. A i r l o c k s w i l l help prevent t o x i c fumes from s p r e a d i n g t o n o n - t o x i c areas i n the event of a f a i l u r e of a p r i m a r y containment c a b i n e t . Check v a l v e s i n the incoming water l i n e s w i l l prevent c o n t a m i n a t i o n o f p o t a b l e water s u p p l i e s when p r e s s u r e i s lost. Secure d o c k a b l e ) s t o r a g e f o r s m a l l q u a n t i t i e s o f t o x i c c h e m i c a l s s h o u l d be a v a i l a b l e i n each room. A c e n t r a l s t o r a g e p o i n t f a c i l i t a t e s i n v e n t o r y i n g , but must accommodate c o m p a t i b i l i t y r e q u i r e m e n t s f o r the s t o r e d i t e m s . P r i m a r y Containment C a b i n e t s The n a t u r e o f the work t o be done, s t a t u t o r y r e q u i r e m e n t s , and the p r e f e r e n c e s o f the s t a f f w i l l d i c t a t e the s e l e c t i o n o f l a b o r a t o r y containment c a b i n e t s , but the f o l l o w i n g c o n s i d e r a t i o n s s h o u l d be taken i n t o account by the d e c i s i o n makers. Glove boxes ( i n c l u d i n g C l a s s I I I c a b i n e t s ) may be n e c e s s a r y f o r most t o x i c o p e r a t i o n s or where a e r o s o l s are i n v o l v e d . Glove boxes p e r m i t the use o f i n e r t or o t h e r w i s e c o n t r o l l e d atmospheres. They s h i e l d the o p e r a t o r d u r i n g use, r e q u i r e l e s s v e n t i l a t i o n than fume hoods, and d o n ' t cease t o p r o t e c t when house power i s l o s t , though t h e y may l o s e t h e i r n e g a t i v e p r e s s u r e . However, c l o s e d g l o v e boxes are i n c o n v e n i e n t . M a t e r i a l s must be passed i n or out through an a i r l o c k or dunk tank and the o p e r a t o r i s a f f o r d e d o n l y l i m i t e d movement by v i r t u e o f the arm l e n g t h g l o v e s being i n a f i x e d l o c a t i o n . S e a l s and g l o v e s w i l l be exposed t o h i g h e r c o n c e n t r a t i o n s o f c h e m i c a l s than would be generated i n a hood, so o r g a n i c s may permeate over a p e r i o d o f t i m e . Glove boxes o f f e r l e s s p r o t e c t i o n w h i l e s e a l s or g l o v e s are b e i n g changed. A l l work i n a c l o s e d g l o v e box i s viewed through g l a s s which seems t o a t t r a c t d i r t on both s u r f a c e s . Fume hoods are o f t e n s e l e c t e d f o r t h e i r convenience o f use though t h e y g r e a t l y c o m p l i c a t e the d e s i g n o f a l a b o r a t o r y . O p e r a t o r s can work c o m f o r t a b l y anywhere i n the hood and m a t e r i a l s



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can be brought i n or out e a s i l y . Gloves can be changed c o n v e n i e n t l y w i t h o u t r i s k i n g o p e r a t o r exposure t o the hood's c o n t e n t s . U n f o r t u n a t e l y , fumes can d r i f t out of a hood f o r a v a r i e t y o f reasons and a e r o s o l s w i l l d r i f t o u t . Hoods s t r a i n h e a t i n g and a i r c o n d i t i o n i n g systems by consuming v a s t q u a n t i t i e s o f room a i r , t h e y are i n c o m p a t i b l e w i t h c o n t r o l l e d atmospheres, t h e y p r o v i d e no s h i e l d i n g w i t h the sash up, and t h e i r p r o t e c t i o n i s degraded by t u r b u l e n t flows i f t h e y are l o c a t e d near doors or i n areas t h a t have heavy p e d e s t r i a n t r a f f i c . Flow at the hood f a c e i s o b s t r u c t e d by workers s t a n d i n g i n f r o n t o f the hood and a l l p r o t e c t i o n i s l o s t when power f a i l u r e s are e x p e r i e n c e d . The l a r g e fans a s s o c i a t e d w i t h hoods may cause severe v i b r a t i o n problems u n l e s s t h e y are a p p r o p r i a t e l y mounted at some c o n s i d e r a b l e d i s t a n c e . The mounting o f blower motors behind the b u i l d i n g can reduce unwanted v i b r a t i o n s i n the l a b o r a t o r i e s , but c a r e must then be taken to a v o i d i r r i t a t i n g l o w - f r e q u e n c y n o i s e from the l e n g t h y duct work. Room a i r s h o u l d be d e l i v e r e d through a p e r f o r a t e d dropped c e i l i n g , as i t i s thus more e v e n l y d e l i v e r e d at lowered v e l o c i t i e s to reduce t u r b u l e n t f l o w s . Each hood i n t e n d e d f o r t o x i c work must have a face v e l o c i t y o f 100 l i n e a r f e e t per m i n u t e . When many hoods are employed, the volume o f tempered a i r t h a t must be s u p p l i e d (summer and w i n t e r ) i s q u i t e l a r g e . The r e q u i r e d a i r h a n d l i n g equipment i s so massive t h a t minor misadjustments may make i t d i f f i c u l t t o get out of a room because o f a i r p r e s s u r e on a d o o r . One way t o deal w i t h t h i s i s to vent the doors and keep the h a l l w a y s at a s l i g h t l y h i g h e r p r e s s u r e than the l a b s . When an a i r h a n d l i n g ( s u p p l y ) u n i t f a l l s s h o r t , the h a l l w a y p r o v i d e s needed makeup a i r . Computers can o p e r a t e a i r h a n d l i n g systems more p r e c i s e l y than can t r a d i t i o n a l systems and an alarm system t h a t p i n p o i n t s d e f e c t i v e elements f o r e a r l y r e p a i r can h e l p a v o i d g r o s s i m b a l a n c e s . Hoods f o r t o x i c work s h o u l d be e a s i l y decontaminatable w i t h a c a t c h b a s i n l e a d i n g t o a t o x i c sump. The hoods s h o u l d be made o f s t a i n l e s s s t e e l and be c o n v e n i e n t l y l o c k e d . P r o v i s i o n s h o u l d be made f o r l i m i t i n g t r a v e l o f the hood door t o t h a t opening which can be supported by the hood fans and the a i r h a n d l i n g s y s t e m . These s t o p s s h o u l d be s t u r d y but a d j u s t a b l e . Hoods may be r e q u i r e d t o c o n t a i n c o n s i d e r a b l e amounts o f equipment w h i l e m a i n t a i n i n g a s p e c i f i e d range o f a i r f l o w at the face. T h e r e f o r e , the hoods must f e a t u r e s e v e r a l i n t e r n a l a i r f l o w adjustments to accommodate the l o c a l i z e d e f f e c t s o f equipment p l a c e d i n the a i r p a t h . The hoods s h o u l d be l a r g e enough t o s e t a l l work back 20 c e n t i m e t e r s or more from the face o f the hood. Access through the r e a r panel makes the r e p a i r o f contaminated equipment much s a f e r . L a b o r a t o r i e s designed f o r the h a n d l i n g o f t o x i c m a t e r i a l s n o r m a l l y m a i n t a i n reduced p r e s s u r e s i n the rooms and h a l l w a y s , r e l a t i v e t o the p r e s s u r e o u t s i d e the b u i l d i n g s . Hoods s h o u l d t h e r e f o r e be f i t t e d w i t h a n t i b a c k f l o w v a l v e s t o a v o i d s u c k i n g the c o n t e n t s o f the ductwork i n t o the l a b o r a t o r y i n the event o f a power f a i l u r e . Backup power p r o v i d e d i n 15 seconds does not p r e v e n t t h i s phenomenon, even i f the hoods and a i r h a n d l e r s are designed to r e s t a r t a u t o m a t i c a l l y . The f l o o r s o f hoods s h o u l d have l i p s f o r c o n t a i n i n g s p i l l s .



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D r a i n s s h o u l d be f i t t e d w i t h d r a i n plugs when not i n use t o ensure t h a t t o x i c s w i l l not be a l l o w e d to go down the d r a i n i n an accident. I t i s advantageous to decontaminate t o x i c m a t e r i a l before i t i s mixed w i t h many g a l l o n s o f d i l u e n t i n a t o x i c sump so the t o x i c d r a i n s h o u l d be r e l i e d upon as a f a l l b a c k s a m p l i n g and treatment p o i n t . O p e r a t i o n s t h a t i n v o l v e t r a n s f e r s o f t o x i c s between c o n t a i n ment c a b i n e t s can be conducted most s a f e l y i f the c a b i n e t s are l o c a t e d adjacent t o one another and f e a t u r e i n t e r c o n n e c t i n g p a s s ageways. C a b i n e t f l o o r s can be equipped w i t h steam baths or s t o r a g e compartments t o m i n i m i z e the frequency w i t h which t o x i c m a t e r i a l s must be packaged up f o r t r a n s f e r t o another safe a r e a . The c l a s s I b i o l o g i c a l s a f e t y c a b i n e t i s i n t e r m e d i a t e between a fume hood and a c l o s e d g l o v e box. T h i s c a b i n e t can be used w i t h the f r o n t open or be f i t t e d w i t h g l o v e s . S i n c e the f r o n t access opening i s n o r m a l l y o n l y 8 inches h i g h , the c a b i n e t r e q u i r e s l e s s v e n t i l a t i o n than a fume hood. C l a s s I c a b i n e t s are used w i t h an a i r f l o w at the face o f 100 l i n e a r f e e t per m i n u t e . Filter

Systems

F i l t e r systems f o r t o x i c c h e m i c a l o p e r a t i o n s u s u a l l y employ a rough p r e f i l t e r f o l l o w e d by a h i g h e f f i c i e n c y p a r t i c u l a t e a i r (HEPA) f i l t e r , i n t u r n f o l l o w e d by c h a r c o a l bed f i l t e r s to remove the c h e m i c a l s . P a i r s o f c h a r c o a l f i l t e r s s h o u l d be connected i n s e r i e s w i t h a sampling p o r t between f i l t e r s so t h a t breakthrough from the f i r s t f i l t e r can be d e t e c t e d w h i l e the excess i s s t i l l being c a p t u r e d by the s e c o n d . Influent f i l t e r i n g of a l l laboratory a i r i s n e c e s s a r y t o reduce the frequency w i t h which replacement o f the contaminated f i l t e r s i s r e q u i r e d . Hood f i l t e r systems s h o u l d be d e s i g n e d t o reduce the hazards o f change out p r o c e d u r e s . One such system has been d e s c r i b e d . ^ ) The f i l t e r e d e f f l u e n t from hoods must never be d i r e c t e d back i n t o the l a b o r a t o r y . I t s h o u l d be r e l e a s e d above the b u i l d i n g at a h i g h enough v e l o c i t y t o ensure t h a t i t w i l l not be p u l l e d i n t o the i n t a k e v e n t s . Waste D i s p o s a l A l l d r a i n s i n a t o x i c l a b o r a t o r y w i t h e x c e p t i o n o f those from the t o i l e t s s h o u l d l e a d t o a t o x i c sump. The t o x i c sump s h o u l d be f i t t e d w i t h the w h e r e w i t h a l t o p e r m i t a d d i t i o n o f r e a g e n t s , a g i t a t i o n , and s a m p l i n g , as w e l l as adequate i n d i c a t o r s and alarms t o h i g h l i g h t m a l f u n c t i o n s . V a l v i n g s h o u l d be c o n v e n i e n t t o o p e r a t e and the system s h o u l d f e a t u r e p a r a l l e l tanks so one batch can be t r e a t e d w h i l e the lab c o n t i n u e s to d i s c h a r g e to the o t h e r t a n k . P r o v i s i o n s h o u l d be p r o v i d e d t o pump out c o n t e n t s when u n t r e a t a b l e . The s t o r a g e o f s o l i d or l i q u i d t o x i c waste r e s i d u e s must be c o n s i d e r e d i n the d e s i g n o f the l a b o r a t o r y complex. Whatever temporary s t o r a g e i s s e l e c t e d , such as berms, s h e d s , e t c . , i t i s i m p e r a t i v e t h a t a l e a k i n g drum not r e s u l t i n c h e m i c a l s being d i s c h a r g e d toward the a q u i f e r . Wastes must not be s t o r e d on s i t e f o r more than 90 days a f t e r c o l l e c t i o n , so the l a b o r a t o r y s t o r a g e



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space may not need to be l a r g e as long as room e x i s t s s e g r e g a t i o n o f c h e m i c a l s as n e c e s s a r y .

for


Compressed Gases When such equipment as chromatographs or atomic a b s o r p t i o n s p e c t r o p h o t o m e t e r s are used, compressed gas tanks p r o l i f e r a t e to the p o i n t where the q u a n t i t i e s o f e n e r g e t i c s are too l a r g e t o be s a f e l y l o c a t e d i n a l a b o r a t o r y i n which t o x i c s are u s e d . Two alternatives exist. Hydrogen can be generated e l e c t r o l y t i c a l l y on s i t e as needed, or i t can be p i p e d from compressed gas c y l i n d e r s through m a n i f o l d s . M a n i f o l d s p e r m i t the c y l i n d e r s to be kept i n a p l a c e more c o n v e n i e n t t o the bulk s t o r a g e p o i n t and reduce the amount of such m a t e r i a l i n a t o x i c l a b o r a t o r y . The m a n i f o l d s s h o u l d be l o c a t e d where t h e y can be checked w i t h a soap s o l u t i o n r e g u l a r l y to f i n d any l e a k s t h a t might have d e v e l o p e d . Manifolds s h o u l d be c o l o r c o d e d . Construction Materials C o n s t r u c t i o n m a t e r i a l s must be nonabsorbent and e a s i l y c l e a n e d or decontaminated. Seamless f l o o r i n g a v o i d s c r a c k s from which s p i l l e d c h e m i c a l s can c o n t r i b u t e a s i g n i f i c a n t p o l l u t i o n burden t o the l a b o r a t o r y a i r . Epoxy p a i n t s h o u l d be used f o r i n t e r i o r w a l l s . Dropped c e i l i n g s s h o u l d be made o f nonabsorbent m a t e r i a l such as enameled m e t a l . Hoods and s i n k s s h o u l d be f a b r i c a t e d o f s t a i n l e s s steel. Wood or o t h e r porous s u r f a c e s must be a v o i d e d . C o n s t r u c t i o n and l a n d s c a p i n g s h o u l d p r o v i d e a p p r o p r i a t e earthquake and storm r e s i s t a n c e as w e l l as good p h y s i c a l s e c u r i t y . Communications T o x i c o p e r a t i o n s must be supported by a good communications s y s t e m . In l a b o r a t o r i e s where communications are i n a d e q u a t e , workers w i l l n a t u r a l l y use " r u n n e r s " f o r communication needs. T h i s p r a c t i c e r e s u l t s i n a v o i d a b l e t r a f f i c i n and out o f t o x i c areas which i n c r e a s e s the o p p o r t u n i t i e s f o r c o n t a m i n a t i o n t o s p r e a d . In e m e r g e n c i e s , a phone or i n t e r c o m can h e l p ensure t h a t a s s i s t a n c e i s t a i l o r e d t o the a c t u a l need. An " a l l purpose" response t o an alarm w i l l n o r m a l l y be l e s s r a p i d at a time when speed may be of the essence. V i d e o cameras t r a i n e d on c r i t i c a l o p e r a t i o n s add a measure o f s a f e t y , but annoy the workers who may f e e l t h a t the p u r pose o f the system i s to "spy" on them. As a minimum, the l a b o r a t o r y doors s h o u l d have windows so t h a t e n t e r i n g personnel d o n ' t blunder i n t o a r a p i d l y d e v e l o p i n g s c e n a r i o . Alarm Systems A g e n e r a l alarm system f o r a t o x i c l a b o r a t o r y s h o u l d f e a t u r e coded p u l l boxes to a i d emergency response p e r s o n n e l i n l o c a t i n g the s p e c i f i c a r e a where the emergency e x i s t s . S u f f i c i e n t audible and v i s i b l e alarms s h o u l d be p r o v i d e d to ensure t h a t a l l personnel are a l e r t e d . The f a c t t h a t maintenance personnel may be caught working at n o i s y l o c a t i o n s above c e i l i n g s , on the r o o f , i n s e r v i c e t u n n e l s or o u t s i d e the b u i l d i n g s h o u l d be c o n s i d e r e d . When



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a c t i v a t e d , the alarms s h o u l d c o n t i n u e to sound u n t i l they are t u r n e d o f f by human i n t e r v e n t i o n . Alarm systems s h o u l d be p r o v i d e d w i t h r e l i a b l e back up power, and s h o u l d f e a t u r e t e s t c i r c u i t s . Klaxons and o t h e r components s h o u l d be c o n t i n u o u s d u t y r a t e d and a l l w i r i n g s h o u l d be encased i n d e d i c a t e d metal c o n d u i t s . Power surges or f a i l u r e s may leave the best designed a i r h a n d l i n g equipment i n v a r i o u s s t a t e s o f d i s a r r a y . It is v a l u a b l e i n such c i r c u m s t a n c e s t o be able to assess the s t a t u s o f the hoods from o u t s i d e the b u i l d i n g . An easy t o read s t a t u s board can be p l a c e d so as to be v i s i b l e from the o u t s i d e through a window and/or remote outputs can be made a v a i l a b l e at o t h e r l o c a t i o n s . Mechanisms f o r r e s e t t i n g the hoods s h o u l d a l s o be c o n v e n i e n t l y located. The exhaust duct o f each v e n t i l a t e d containment c a b i n e t must be f i t t e d w i t h an a d j u s t a b l e low flow s e n s o r . A u d i b l e and v i s i b l e alarms must be l o c a t e d near the c a b i n e t , and the s i l e n c e s w i t c h s h o u l d e n e r g i z e an i n d i c a t o r at the s t a t u s b o a r d . These are l o c a l alarms which s h o u l d not a u t o m a t i c a l l y t r i g g e r a c a l l f o r emergency response p e r s o n n e l . An alarm system s h o u l d be p r o v i d e d t o warn workers o f power i n t e r r u p t i o n s t h a t have o c c u r r e d d u r i n g non-duty h o u r s . Such e v i d e n c e t h a t e n g i n e e r i n g c o n t r o l s have been compromised a l e r t s incoming personnel t o the n e c e s s i t y f o r f i r s t e n t r y m o n i t o r i n g o f l a b o r a t o r y rooms. Power Ground f a u l t i n t e r r u p t e r s s h o u l d be i n c l u d e d i n a l l c i r c u i t s used t o power l a b o r a t o r y i n s t r u m e n t a t i o n . C i r c u i t b r e a k e r s s h o u l d be near the areas they s e r v e . Emergency l i g h t i n g must be p r o v i d e d i n each room, h a l l w a y and s t a i r c a s e . I t i s common p r a c t i c e to u t i l i z e b a t t e r y powered l i g h t s f o r t h i s p u r p o s e . House power i s used t o keep the b a t t e r i e s c h a r g e d . Security The use o f t o x i c s c a r r i e s w i t h i t a r e s p o n s i b i l i t y t o m a i n t a i n an e f f e c t i v e system t o ensure t h a t dangerous c h e m i c a l s are not r e l e a s e d to u n a u t h o r i z e d p e r s o n s . The e n t i r e b u i l d i n g s h o u l d be w i t h i n a secure p e r i m e t e r and/or i n d i v i d u a l l a b o r a t o r i e s or s u i t e s of l a b o r a t o r i e s s h o u l d be s e c u r a b l e . W i t h i n l a b o r a t o r i e s and stockrooms t h e r e s h o u l d be secure s t o r a g e f o r any t o x i c s and o t h e r c o n t r o l l e d substances t h a t are u s e d . S e c u r i t y systems are a v a i l a b l e f e a t u r i n g magnetic badges, p e r s o n n e l i d e n t i f i c a t i o n numbers, p a s s p h r a s e s , or even d i g i t a l or r e t i n a l scanners t h a t unlock those s p e c i f i c areas t o which the i n d i v i d u a l employee has been granted a c c e s s . S i n c e these systems are computer c o n t r o l l e d , the access a u t h o r i z a t i o n f o r any i n d i v i d u a l can be c o n v e n i e n t l y and q u i c k l y adjusted as circumstances warrant. Logging of t r a f f i c i n the v a r i o u s areas can be accomplished a u t o m a t i c a l l y . I t s h o u l d be understood t h a t c o m p u t e r i z e d systems are s u s c e p t i b l e t o i n t r u s i o n and may t h e r e f o r e l a c k the p o s i t i v e c o n t r o l o f a w e l l o r g a n i z e d and m o n i t o r e d system o f secure keys or c o m b i n a t i o n s .


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Literature Cited 1. Barberto, M. S. In Toxic Chemical and Explosive Facilities; Scott, R. Α., Ed.; ACS Symposium Series No. 96; American Chemical Society: Washington, DC, 1979; pp 192-214.


RECEIVED May 13, 1987


Design Considerations for Toxic Laboratories - American Chemical

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