10 Rapid Suppression of Explosive and Incendiary Fires
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CHRIS C. ELKINS Day & Zimmermann, Inc., Operating Contractor of Lone Star Army Ammunition Plant, Texarkana, TX 75501
In 1951 Day & Zimmermann, Inc. was awarded an initial contract to operate the Lone Star Army Ammunition Plant. Fire protection systems for equipment and processes consisted of fuzeable links and quartzoid bulbs for sensing fires. In the early 1950's, a plan was initiated to replace the existing systems with the improved Heat Actuating Device. The H-A-D greatly improved the effectiveness of the deluge systems and was considered adequate at the time. Introduction of new materials and processes created new problems due to the frequent fires and explosions. These problems surfaced in the late1960'sand early 1970's. A search for an ultra-high speed fire protection system was begun during this period. Ultra-high speed is a term that measures in milliseconds as compared to high speed, such as the H-A-D which measures in seconds. It has been said that necessity is the Mother of Invention, but at Lone Star Army Ammunition Plant, it was the Mother of Motivation. The cost of repair of fire damage was running high and our people had become very skittish. The feeling of urgency compelled us to find or design a better fire protection system. In 1972, Day & Zimmermann engineers started a test program. One of the first steps was to select the type of sensor or detector. Consideration was given to infra-red, ultraviolet, and audio signals. After careful study of the alternatives, the ultraviolet was chosen, primarily because of available components and that it would not be affected by sunlight. Audio was discarded because of frequent thunderstorms during the rainy season. The second major component selected was the deluge valve. It was to be a fast-operating valve located as close to the nozzle as practical. Automatic Sprinkler had such a valve that was built into the nozzle. This would provide a wet system in close proximity of the fire initiation point. It would be pilot-operated for fast response.
0-8412-0481-0/79/47-096-187$05.00/0 © 1979 American Chemical Society
Scott; Toxic Chemical and Explosives Facilities ACS Symposium Series; American Chemical Society: Washington, DC, 1979.
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TOXIC C H E M I C A L A N D EXPLOSIVES FACILITIES
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The t h i r d m a j o r component w o u l d be t h e c o n t r o l l e r t h a t t a k e s the s i g n a l from t h e u l t r a v i o l e t s e n s o r and a m p l i f i e s i t t o a power v o l t a g e t h a t o p e r a t e s t h e v a l v e . The c o n t r o l l e r was c o n s t r u c t e d o f s t a n d a r d e l e c t r i c a l components t h a t were on h a n d . In a d d i t i o n t o o p e n i n g t h e v a l v e , i t w o u l d s h u t o f f t h e power t o t h e m a c h i n e s t o p r e v e n t a d d i t i o n a l damage and w o u l d a l s o s o u n d an alarm. T h e s e components were a s s e m b l e d , and a t e s t was c o n d u c t e d t o compare t h e new s y s t e m w i t h t h e H - A - D and q u a r t z o i d s y s t e m s . The f i r s t s e r i e s o f t e s t s u s e d v a r i o u s t e s t m a t e r i a l s s u c h as T N T , p r o p e l l a n t p o w d e r s , d e l a y c o m p o s i t i o n s , and b l a c k p o w d e r . E l e c t r i c m a t c h e s were t i e d i n t o a common power s o u r c e t o give simultaneous i g n i t i o n o f the t e s t samples. M o v i e f i l m was used to r e c o r d the t e s t r e s u l t s . Frames o f t h e s l o w m o t i o n f i l m were c o u n t e d t o d e t e r m i n e t h e a p p r o x i m a t e r e s p o n s e t i m e o f t h e systems. The r e s u l t s o f t h e f i r s t s e r i e s o f t e s t s i n d i c a t e d t h a t t h e u l t r a v i o l e t s e n s o r d e l u g e s y s t e m was c o n s i d e r a b l y f a s t e r t h a n t h e H - A - D and the o l d e r s e n s o r , t h e q u a r t z o i d . In f a c t , t h e q u a r t zoid sensor never actuated during these t e s t s . The r e s p o n s e t i m e f r o m i n i t i a t i o n o f t h e t e s t s a m p l e u n t i l d e l u g e w a t e r was on t h e f i r e r a n g e d f r o m 300 t o 400 m i l l i s e c o n d s f o r t h e u l t r a v i o l e t system. T h i s r e s p o n s e t i m e was a d e q u a t e t o s u p p r e s s f i r e s f r o m most o f o u r c h e m i c a l s and e x p l o s i v e s . T h e one e x c e p t i o n d i s c o v e r e d d u r i n g t h e t e s t s was a b l a c k powder f i r e . U n l i k e a l l the o t h e r m a t e r i a l s , t h e b l a c k powder s a m p l e was c o m p l e t e l y consumed by the f i r e . Even though the system f a i l e d f o r b l a c k powder, the s e r i e s o f t e s t s gave m e r i t t o t h e u l t r a v i o l e t s e n s o r d e l u g e and provided a d d i t i o n a l v a l u a b l e i n f o r m a t i o n which approximated the r e s p o n s e t i m e o f t h e c o n t r o l s and v a l v e . A s e c o n d s e r i e s o f t e s t s was c o n d u c t e d s p e c i f i c a l l y t o i m p r o v e t h e r e s p o n s e t i m e o f t h e s y s t e m and e x t i n g u i s h t h e b l a c k powder f i r e . T h e o n l y c h a n g e i n t h e t e s t s e t - u p was t h e u s e o f s o l i d s t a t e c o n t r o l s i n l i e u o f the c o n v e n t i o n a l ones u s e d d u r i n g the f i r s t t e s t s . T h e r e t e s t s were made and t h e r e s p o n s e t i m e was r e d u c e d i n h a l f ; b u t a g a i n t h e e n t i r e s a m p l e was consumed and t h e s y s t e m was n o t c o n s i d e r e d t o be e f f e c t i v e . B e f o r e t h e t h i r d s e r i e s o f t e s t s was made, a d d i t i o n a l r e s e a r c h was r e q u i r e d t o f i n d o r d e v e l o p an u l t r a - f a s t o p e n i n g valve. T h i s was t h e o n l y m a j o r component t h a t c o u l d be r e p l a c e d to f u r t h e r reduce the response t i m e . Information from Detector E l e c t r o n i c s C o r p o r a t i o n i n t r o d u c e d us t o a v a l v e m a n u f a c t u r e d b y G r i n n e l l , c a l l e d t h e P r i m a c v a l v e , w h i c h seemed t o f i t t h e b i l l . The v a l v e u s e s a p r i m e r d e t o n a t i n g d e v i c e w i t h r e d u n d a n t d e t o n a t o r s t o blow the v a l v e open. The same e l e c t r i c a l s i g n a l i n i t i a t e d b y t h e u l t r a v i o l e t s e n s o r c o u l d now be u s e d t o a c t u a t e the d e t o n a t o r s , thus f u r t h e r r e d u c i n g l o s t m o t i o n . T h e t e s t s e t - u p was m o d i f i e d s l i g h t l y f r o m t h e p r e v i o u s t e s t i n t h a t t h e b l a c k powder was s p r e a d a l o n g a p a t h one i n c h w i d e and 30 i n c h e s l o n g w i t h t h e e l e c t r i c match a t one end and a c u p
Scott; Toxic Chemical and Explosives Facilities ACS Symposium Series; American Chemical Society: Washington, DC, 1979.
Downloaded by CORNELL UNIV on August 31, 2016 | http://pubs.acs.org Publication Date: April 6, 1979 | doi: 10.1021/bk-1979-0096.ch010
10.
ELKINS
Rapid
Suppression
of
Fires
189
with s e v e r a l ounces of powder at the other. The i n t e n t i o n was to measure the d i s t a n c e the f i r e burned before or i f the f i r e was extinguished. The t e s t s were recorded on Fastex f i l m taken at 4200 frames per second. The reponse time from i g n i t i o n u n t i l water was on the f i r e was 62 m i l l i s e c o n d s . The response time had again been cut i n h a l f . Nineteen inches o f black powder were consumed i n the t e s t . In order to get the water on the f i r e a l i t t l e f a s t e r , the l i n e pressure (approximately 75 p s i ) was increased to 100 p s i and the system was r e t e s t e d . T h i s time, only s i x inches of powder were consumed. This system i s considered h i g h l y e f f e c t i v e and i s i n use today at our b l a c k powder loading o p e r a t i o n . Day § Zimmermann has i n s t a l l e d approximately 90 u l t r a v i o l e t sensor deluge systems i n the Lone S t a r and Kansas Army Ammunition P l a n t s . The Primac valve i s only used i n the b l a c k powder opera t i o n because o f i t s higher c o s t . A l l other m a t e r i a l s use the system as d e s c r i b e d i n the second s e r i e s o f t e s t s and i s considered highly e f f e c t i v e . Because o f the nature o f our business, we continue to have the f i r e s but the cost i s g e n e r a l l y n e g l i g i b l e i n comparison to the cost o f f i r e damage when the o l d systems were i n use. Production downtime has been g r e a t l y reduced, and the operators working the l i n e s f e e l much s a f e r . C e r t a i n l y the u l t i m a t e f i r e p r o t e c t i o n system has not been achieved, but we f e e l at t h i s time that we are pushing the s t a t e of-the-art . RECEIVED November 22,
1978.
Scott; Toxic Chemical and Explosives Facilities ACS Symposium Series; American Chemical Society: Washington, DC, 1979.
