ozone chemistry and technology - ACS Publications

Application of Ozone from Sterilamp in Control of Mold, Bacteria, and Odors RUDOLPH N A G Y

Downloaded by AUBURN UNIV on September 12, 2017 | http://pubs.acs.org Publication Date: January 1, 1959 | doi: 10.1021/ba-1959-0021.ch009

Westinghouse Electric Corp., Bloomfield, N. J.

In using a Sterilamp for the tenderization a n d preservation of meat a n d the preservation of other types of foods, a controlled amount of ozone is generated by the lamp to destroy or suppress growth of mold a n d bacteria in the unirradiated areas. Minute amounts of ozone are also used to destroy odors in both commercial a n d domestic refrigerators a n d in air-conditioning systems.

A low-pressure m e r c u r y l a m p sold b y Westinghouse under the t r a d e - m a r k , S t e r i l a m p , w a s p l a c e d o n t h e m a r k e t i n 1936. T h e l a m p w a s p r i m a r i l y designed t o e m i t a c o p i o u s a m o u n t of b a c t e r i c i d a l u l t r a v i o l e t r a d i a t i o n w i t h a m i n i m u m a m o u n t of r a d i a t i o n b e l o w 2000 A . T h e l a t t e r r a d i a t i o n is r e s p o n s i b l e f o r t h e p h o t o c h e m i c a l p r o d u c t i o n of ozone f r o m o x y g e n of t h e a i r . T h e effectiveness of t h e l a m p i n d e s t r o y i n g b a c t e r i a (25) a n d m o l d (21) o n P e t r i p l a t e s , i n o p e r a t i n g r o o m s (17,18), b a c t e r i o l o g i c a l l a b o r a t o r i e s (32), a n d a i r - c o n d i t i o n i n g s y s t e m s (22, 24) h a s b e e n a m p l y d e m o n s t r a t e d . I n some a p p l i c a t i o n s of t h e l a m p , i t w a s s o o n d i s c o v e r e d t h a t a c o n t r o l l e d a m o u n t of ozone, t o g e t h e r w i t h t h e b a c t e r i c i d a l r a d i a t i o n , r e s u l t e d i n a m o r e effective m e t h o d of d e s t r o y i n g m i c r o o r g a n i s m s . O z o n e also o x i d i z e d m a n y of t h e odors. T h e present s u r v e y describes o n l y those a p p l i c a t i o n s of t h e S t e r i l a m p t u b e w h i c h u t i l i z e l a m p s g e n e r a t i n g a c o n t r o l l e d a m o u n t of ozone t o d e s t r o y m o l d , b a c t e r i a , a n d o d o r s . Tenderay

Process

O n e of t h e first a p p l i c a t i o n s of t h e g e r m i c i d a l l a m p w a s i n t h e t e n d e r i z i n g of m e a t (1, 19). F r e s h beef sides w h i c h h a v e b e e n p a r t i a l l y c h i l l e d i n a c o o l e r a r e h e l d f o r 42 to 44 h o u r s a t 6 8 ° F . a t a r e l a t i v e h u m i d i t y of a b o u t 8 5 % . I n c r e a s e i n tenderness of m e a t d u r i n g storage r e s u l t s f r o m t h e d i g e s t i v e a c t i o n of n a t u r a l l y c o n t a i n e d e n z y m e s u p o n t h e m u s c u l a r a n d c o n n e c t i v e tissues i n t h e m e a t . T h e i n c r e a s e d t e m p e r a t u r e g r e a t l y accelerates t h i s e n z y m e a c t i o n , so t h a t t h e degree of tenderness is e q u i v a l e n t t o beef h u n g f o r 20 d a y s a t 4 0 ° F . H o w e v e r , t h e increase of t e m p e r a t u r e also p r o v i d e s a m o r e f a v o r a b l e e n v i r o n m e n t f o r t h e g r o w t h of m o l d a n d b a c t e r i a . T h e p u r p o s e of t h e S t e r i l a m p u l t r a v i o l e t t u b e s i s t o d e s t r o y these s u r f a c e o r g a n i s m s . F i g u r e 1 i s a t y p i c a l i n s t a l l a t i o n of t h i s process. A p p r o x i m a t e l y 170,000,000 p o u n d s of beef p e r y e a r a r e tenderized b y this method. R e s u l t s of tests d u r i n g t h e d e v e l o p m e n t of t h i s process s h o w e d t h a t a c o n t r o l l e d a m o u n t of ozone w a s n e c e s s a r y t o d e s t r o y m o l d o r b a c t e r i a o n p o r t i o n s of m e a t n o t 57

OZONE CHEMISTRY AND TECHNOLOGY Advances in Chemistry; American Chemical Society: Washington, DC, 1959.


A D V A N C E S IN CHEMISTRY SERIES

Figure

1.

Typical Tenderay process room, showing stalling Sterilamp tube

Figure

Top shelf

Bottom shelf

2.

Slime-forming meat

organisms box

method

exposed

of in-

in

Ozone, 24 hours

Ozone, 48 hours

Control

Ultraviolet, top, 24 hours

Control

Ultraviolet, bottorn, 24 hours

Ozone, 24 hours

Ozone, 48 hours

Ozone, 72 hours


N A G Y - C O N T R O L OF MOLD, BACTERIA,

ODORS

59

d i r e c t l y i r r a d i a t e d b y t h e l a m p s . Q u a n t i t a t i v e d e t e r m i n a t i o n s of t h e effectiveness of ozone were m a d e b y b a c t e r i a c o u n t s t a k e n f r o m t h e s u r f a c e of t h e m e a t a n d b y e x p o s i n g P e t r i p l a t e s seeded w i t h b a c t e r i a a n d m o l d t a k e n f r o m i n f e c t e d m e a t . F i g u r e 2 i s a n e x a m p l e of o r g a n i s m s o n P e t r i p l a t e s e x p o s e d t o d i r e c t r a d i a t i o n p l u s ozone a n d s o m e t o ozone alone. T h e l a t t e r P e t r i p l a t e s were i n v e r t e d a n d p l a c e d i n v a r i o u s p o s i t i o n s i n t h e r e f r i g e r a t o r . F i g u r e 2 shows t h a t a b o u t 72 h o u r s a r e necessary b e f o r e a l l of t h e organisms are destroyed.


T h e c o n c e n t r a t i o n of ozone i n s u c h t e n d e r i z i n g r o o m s , a c c o r d i n g t o E w e l l (11, 12), i s of t h e o r d e r of 0.1 p . p . m . b y v o l u m e . E l f o r d a n d V a n d e n E n d e (6) h a v e s h o w n t h a t ozone as l o w as 0.04 p . p . m . c a n d e s t r o y b a c t e r i a i f t h e r e l a t i v e h u m i d i t y is 60 t o 9 0 % . M a l l m a n n a n d C h u r c h i l l (20), e x p e r i m e n t i n g w i t h n a t u r a l l y c o n t a m i n a t e d beef, also s h o w e d t h a t 0.1 p . p . m . b y v o l u m e of ozone w o u l d r e t a r d t h e g r o w t h of t h e organisms. B o t h b a c t e r i c i d a l r a d i a t i o n a n d ozone c a n d e s t r o y o n l y t h e s u r f a c e o r g a n i s m s . H e a v y g r o w t h of m o l d a n d b a c t e r i a w i l l n o t b e d e s t r o y e d b y these s m a l l a m o u n t s of ozone. T h e l e n g t h of t i m e necessary t o d e s t r o y a l l of t h e o r g a n i s m s seeded o n a P e t r i p l a t e w o u l d b e a f u n c t i o n o f t h e c o n c e n t r a t i o n of o z o n e . E w e l l (7) h a s s h o w n t h a t t h e r e c i p r o c i t y l a w , w h i c h r e q u i r e s t h a t t h e p e r cent k i l l i n g b e p r o p o r t i o n a l t o t h e c o n c e n t r a t i o n t i m e s d u r a t i o n of ozone, h o l d s f o r a l i m i t e d c o n c e n t r a t i o n . A t l o w c o n c e n t r a t i o n s of ozone a n d v e r y l o n g t i m e s c o r r e s p o n d i n g t o t h e n u m b e r of l i f e cycles of t h e o r g a n i s m , t h e t o t a l a m o u n t of ozone (23) o r u l t r a v i o l e t e n e r g y (25) i s m u c h less f o r t h e same p e r cent of d e s t r u c t i o n of t h e o r g a n i s m s . T h e s e results w o u l d i n d i c a t e t h a t , a t one stage of t h e i r l i f e c y c l e , m o l d a n d b a c t e r i a a r e v e r y s e n s i t i v e t o m i n u t e a m o u n t s of these l e t h a l agents. T h e c o n c e n t r a t i o n of ozone i n t h e t e n d e r i z i n g r o o m i s c o n t r o l l e d b y t h e n u m b e r a n d t y p e of u l t r a v i o l e t l a m p s . M o s t o f t h e l a m p s i n s u c h a r o o m e m i t p r e d o m i n a n t l y b a c t e r i c i d a l r a d i a t i o n . A c e r t a i n p e r c e n t a g e of t h e l a m p s a r e of a s p e c i a l t y p e t h a t e m i t a c o n t r o l l e d a m o u n t of r a d i a t i o n b e l o w 2000 A . T h i s r a d i a t i o n is a c t i v e i n t h e p h o t o c h e m i c a l p r o d u c t i o n of ozone f r o m o x y g e n of t h e a i r . S o m e of t h e ozone i s d e c o m p o s e d b y 2 5 3 7 - A . r a d i a t i o n (9, 10) b e f o r e i t c a n b e u t i l i z e d i n t h e d e s t r u c t i o n of m o l d a n d b a c t e r i a o r t h e o x i d a t i o n of o d o r s . T h e h a l f l i f e of t h e ozone m o l e c u l e u n d e r t h e p r e s e n t c o n d i t i o n s of h u m i d i t y a n d t e m p e r a t u r e s i s p r o b a b l y of t h e o r d e r o f 3 m i n u t e s (9). T h u s , a n a c c u m u l a t i o n of ozone i n s u c h a r o o m i s i m p o s s i b l e . M e a s u r e m e n t of t h e c o n c e n t r a t i o n of ozone s o o n a f t e r t h e i n t r o d u c t i o n of m e a t i n t o a t e n d e r i z i n g r o o m shows a m a r k e d r e d u c t i o n i n t h e a m o u n t of t h i s gas. T h i s c a n b e a t t r i b u t e d t o t h e o x i d a t i o n of o d o r s a s s o c i a t e d w i t h f r e s h m e a t .

M e a t Storage

Rooms

a n d Walk-In Coolers

M e a t t a k e n f r o m t h e r o o m w h e r e t h e T e n d e r a y process i s c a r r i e d o u t i s i m m e d i ately cooled below 40° F . to inhibit the enzyme action responsible f o r t h e tenderization. T h e r a t e of g r o w t h of b a c t e r i a a n d m o l d i s g r e a t l y r e d u c e d a t these l o w t e m p e r a t u r e s . T h e h a l f life of t h e ozone m o l e c u l e (9) h a s b e e n e x t e n d e d t o o v e r 6 m i n u t e s because of t h e l o w e r t e m p e r a t u r e a n d m a r k e d r e d u c t i o n i n t h e a b s o l u t e h u m i d i t y as w e l l as a r e d u c t i o n i n t h e o d o r l e v e l . U n d e r these c o n d i t i o n s t h e n u m b e r of u l t r a v i o l e t l a m p s necessary i s decreased t o a b o u t o n e h a l f o f t h a t u s e d i n t h e r o o m w h e r e t h e T e n d e r a y process is c a r r i e d o u t . H o w e v e r , t h e r a t i o o f t h e b a c t e r i c i d a l l a m p s t o t h e u l t r a v i o l e t l a m p s also p r o d u c i n g a c o n t r o l l e d a m o u n t o f ozone is k e p t c o n s t a n t . T h e c o n c e n t r a t i o n of ozone i n s u c h a r e f r i g e r a t o r h a s b e e n s t a t e d b y E w e l l (8, 10) t o b e a p p r o x i m a t e l y 0.1 p . p . m . b y v o l u m e . T e s t s u s i n g P e t r i p l a t e s seeded w i t h b a c t e r i a t a k e n f r o m i n f e c t e d m e a t s h o w r e s u l t s s i m i l a r t o those seen i n F i g u r e 2 . A t y p i c a l w a l k - i n cooler is s h o w n i n F i g u r e 3. I f t h e t e m p e r a t u r e i n w a l k - i n coolers is a p p r o x i m a t e l y 4 0 ° F . , t h e n u m b e r a n d t y p e of u l t r a v i o l e t l a m p s u s e d f o r a g i v e n a r e a w i l l be t h e same as f o r t h e m e a t storage r e f r i g e r a t o r s . A t t e m p e r a t u r e s



60


Figure 3.

Typical walk-in cooler with Sterilamp tubes on ceiling

b e t w e e n 3 2 ° a n d 3 5 ° F . a m b i e n t , t h e u l t r a v i o l e t o u t p u t of m o s t m e r c u r y l a m p s i s t o o s m a l l t o b e p r a c t i c a l unless steps a r e t a k e n t o increase t h e t e m p e r a t u r e of t h e l a m p . T h e d e s i g n of t h e S t e r i l a m p t u b e p e r m i t s o p e r a t i o n a t these t e m p e r a t u r e s .

Domestic

Refrigerators

C o n s i d e r a b l e r e s e a r c h w a s d o n e o n t h e a p p l i c a t i o n of a n o z o n e - p r o d u c i n g l a m p f o r d o m e s t i c r e f r i g e r a t o r s . I t w a s necessary t o find a b a l a n c e b e t w e e n t h e a m o u n t of u l t r a v i o l e t r a d i a t i o n a n d ozone so t h a t m o l d a n d b a c t e r i a o n t h e f o o d a n d r e f r i g e r a t o r w a l l w o u l d be d e s t r o y e d , w h i l e t h e l e v e l of f o o d o d o r s a n d t h e t r a n s f e r of f o o d o d o r s t o o t h e r foods w o u l d b e g r e a t l y r e d u c e d w i t h o u t c a u s i n g r e a c t i o n s i n c e r t a i n s e n s i t i v e foods. T w o r e f r i g e r a t o r s were l o a d e d w i t h f o o d as s h o w n i n F i g u r e 4. O n e of t h e boxes contained a n u l t r a v i o l e t l a m p w h i c h operated only on the o n cycle, while t h e other b o x w a s t h e c o n t r o l . D a i l y o b s e r v a t i o n s of t h e foods s h o w e d t h a t t h e o d o r l e v e l i n t h e b o x w i t h t h e l a m p as w e l l as t h e t r a n s f e r of o d o r s f r o m one f o o d t o a n o t h e r c a n be r e d u c e d t o a l a r g e degree. B a c t e r i a a n d m o l d o n f o o d a n d o n t h e w a l l s o f a h i g h h u m i d i t y b o x a r e d e s t r o y e d b y t h e m i n u t e a m o u n t s of ozone g e n e r a t e d b y t h e l a m p . T h e a v e r a g e c o n c e n t r a t i o n of ozone is a p p r o x i m a t e l y 0.1 p . p . m . b y v o l u m e (10, 11). F i g u r e 5 shows t h a t m o r e t h a n 48 h o u r s of e x p o s u r e t o t h e ozone is n e c e s s a r y before a l l of t h e o r g a n i s m s a r e d e s t r o y e d o n seeded P e t r i p l a t e s . H i g h e r c o n c e n t r a t i o n s of ozone w i l l d e s t r o y t h e o r g a n i s m s i n a s h o r t e r t i m e ; h o w e v e r , r a n c i d i t y w o u l d b e p r o d u c e d i n some foods. C o n c e n t r a t i o n s of ozone w h i c h w o u l d necessitate l o n g e r exposures of t h e P e t r i p l a t e s before a l l of t h e o r g a n i s m s w e r e d e s t r o y e d w o u l d n o t be so effective i n o x i d i z i n g t h e odors. T h u s , t h e r a t e of d e s t r u c t i o n of o r g a n i s m s i s a m e a s u r e of t h e a m o u n t of ozone i n t h e b o x . T h i s m e t h o d c a n also b e u s e d t o d e t e r m i n e t h e c i r c u l a t i o n of a i r c o n t a i n i n g ozone i n a r e f r i g e r a t o r .



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61

Figure 4. Domestic refrigerator used to study effect of ultraviolet radiation on various foods a n d bacteria

Cheese Ripening

and

Storage

T h e S t e r i l a m p u l t r a v i o l e t t u b e p r o d u c i n g a m i n u t e a m o u n t of ozone has b e e n u s e d t o d e s t r o y m o l d o n C h e d d a r cheese d u r i n g r i p e n i n g (13, llf). E w e l l (11) h a s r e p o r t e d t h a t less t h a n 0.2 p . p . m . b y v o l u m e w i l l e x t e n d t h e h o l d i n g t i m e b y 11 weeks a t 5 9 ° F . a n d 8 0 t o 8 5 % r e l a t i v e h u m i d i t y before t h e a p p e a r a n c e of v i s i b l e m o l d o n t h e cheese. T h e ozone also o x i d i z e d t h e o d o r i n t h e r o o m .

Apple

Storage

T h e use of ozone i n c o n t r o l of s u r f a c e m o l d o n p a c k a g e s a n d w a l l s i n a p p l e storage a n d m a i n t e n a n c e of a p l e a s a n t o d o r h a s been r e p o r t e d b y a n u m b e r of i n v e s t i g a t o r s (12, 16, 28, 81). O z o n e h a s also b e e n u s e d t o r e t a r d r i p e n i n g of f r u i t s . E t h y l e n e gas l i b e r a t e d b y f r u i t s t i m u l a t e s t h e r i p e n i n g . T h e gas is r e a d i l y o x i d i z e d b y ozone (2, H). T h e S t e r i l a m p t u b e h a s b e e n u s e d t o p r o v i d e a c o n t r o l l e d a m o u n t of ozone t o o x i d i z e t h i s gas a n d o t h e r o d o r s as w e l l as t o d e s t r o y m i c r o o r g a n i s m s i n a p p l e storage r o o m s .


A D V A N C E S IN


62

Figure 5.

Slime-forming organisms exposed to ozone in domestic refrigerator 1. 2. 3. 4. 5.

Air

CHEMISTRY SERIES

Control Top left, indirect, 24 hours Top left, indirect, 48 hours Top right, indirect, 24 hours Top right, indirect, 48 hours

Conditioning

T h e p r i m a r y p u r p o s e of t h e S t e r i l a m p t u b e i n a i r - c o n d i t i o n i n g s y s t e m s has b e e n t o d e s t r o y m i c r o o r g a n i s m s (22). T e s t s o n t h e effect of 1 t o 2 p . p . m . b y v o l u m e of ozone o n E. coli s p r a y e d i n t o a n a i r d u c t r e v e a l e d t h a t t h e o r g a n i s m s w e r e n o t d e s t r o y e d . T h i s w o u l d c o n f i r m t h e d a t a of E l f o r d a n d V a n d e n E n d e (6) t h a t ozone is a p o o r d i s i n f e c t a n t of a i r a t l o w r e l a t i v e h u m i d i t y . A t h i g h r e l a t i v e h u m i d i t y these a u t h o r s f o u n d t h a t as l o w as 0.04 p . p . m . b y v o l u m e d e s t r o y e d b a c t e r i a d i s p e r s e d i n a n a e r o s o l . T h i s w o u l d also agree w i t h t h e results r e p o r t e d here, t h a t o r g a n i s m s o n s u r faces a n d seeded o n P e t r i p l a t e s c a n be d e s t r o y e d b y m i n u t e a m o u n t s of o z o n e . W i t h t h e i n t r o d u c t i o n o f a S t e r i l a m p t u b e p r o d u c i n g a c o m t r o l l e d a m o u n t of ozone, t h e r e has been a n i n c r e a s i n g n u m b e r of i n s t a l l a t i o n s f o r t h e p u r p o s e of o x i d i z i n g b o d y , smoke, or cooking odors. T h e l a m p s h a v e been i n s t a l l e d i n t h e a i r d u c t s of l a r g e office



N A G Y — C O N T R O L OF MOLD, BACTERIA, ODORS

Figure 6.

63

Installation of Sterilamp tubes in large air duct

buildings, hospitals, a n d cooking establishments ( F i g u r e 6 ) . Smaller units have been u s e d i n t h e h o t a i r h e a t i n g s y s t e m s of h o m e s a n d s t i l l s m a l l e r u n i t s f o r offices o r i n d i v i d u a l rooms. T e s t s o n a n u m b e r of these s m a l l u n i t s r e v e a l e d t h a t t h e ozone c o n c e n t r a t i o n i n t h e r o o m w a s less t h a n 0.01 p . p . m . b y w e i g h t . T h e r e is a m p l e evidence t h a t v a r i o u s f o o d odors, s u c h as f r o m fish, onions, a c r o l i n f r o m b u r n t f a t , a n d t o b a c c o as w e l l as b o d y odors c a n b e o x i d i z e d b y ozone. T h i s i s s u b s t a n t i a t e d b y m a n y r e p o r t s i n t h e l i t e r a t u r e [4,13-15, 30,31). Tests made i n the laboratory w i t h various unsaturated organic c o m p o u n d s s u c h as i n d o l e a n d s k a t o l e (fecal o d o r ) , a l l y l sulfide ( g a r l i c o d o r ) , a n d m e t h y l t h i o c y a n a t e ( u n p l e a s a n t o d o r of a l m o n d s ) s h o w e d t h e m t o b e r e a d i l y o x i d i z e d , as e v i d e n c e d b y l a c k of o d o r . S a t u r a t e d c o m p o u n d s s u c h as b u t y r i c a n d v a l e r i c acids were n o t o x i d i z e d u n d e r t h e same c o n d i t i o n s . S p e c i a l fixures w i t h u l t r a v i o l e t l a m p s p r o d u c i n g a c o n t r o l l e d a m o u n t of ozone a r e u s e d i n a n i m a l h o s p i t a l s a n d k e n n e l s f o r p r e v e n t i o n of cross i n f e c t i o n a n d f o r t h e o x i d a t i o n of a n i m a l a n d f e c a l o d o r s . Determination of

Ozone

I n f o r m a t i o n o n t h e a m o u n t of ozone g e n e r a t e d b y t h e l a m p u n d e r v a r i o u s c o n d i t i o n s is of i n t e r e s t t o t h e r e s e a r c h s c i e n t i s t , a p p l i c a t i o n engineer, a n d h e a l t h officer. M a n y of t h e d i v e r g e n t v i e w s o n t h e b a c t e r i c i d a l effect a n d t o x i c i t y of ozone c a n be a t t r i b u t e d t o t h e m e t h o d s of d e t e r m i n a t i o n u s e d b y t h e a u t h o r s as w e l l as t h e p u r i t y of t h e i r g a s . A s a n e x a m p l e , oxides of n i t r o g e n were p r o d u c e d as a b y - p r o d u c t b y some o f t h e e a r l y ozone g e n e r a t o r s . T h e s e oxides r e a c t w i t h s o m e of t h e reagents u s e d f o r t h e m e a s u r e m e n t of o z o n e ; t h e y h a v e also been s h o w n t o be t o x i c (5, 26). U l t r a v i o l e t l a m p s d o n o t p r o d u c e oxides of n i t r o g e n . T h e c o n c e n t r a t i o n of ozone i n T e n d e r a y process r o o m s a n d r e f r i g e r a t o r s h a s b e e n d e t e r m i n e d b y E w e l l (9) u s i n g c a l i b r a t e d p o t a s s i u m i o d i d e - s t a r c h p a p e r . T h i s m e t h o d is n o t a p p l i c a b l e f o r c o n c e n t r a t i o n s l o w e r t h a n 0.4 p . p . m . b y v o l u m e . M e a s u r e m e n t of c o n c e n t r a t i o n s b e l o w 0.1 p . p . m . b y v o l u m e i n v o l v e d i n s t a l l i n g a l a r g e n u m b e r of k n o w n lamps i n a refrigerator a n d then dividing the reading to obtain a value for a box w i t h a n o r m a l n u m b e r of l a m p s . T h e p o t a s s i u m i o d i d e - s t a r c h p a p e r w a s l a t e r c o m p a r e d w i t h t h e C r a b t r e e a n d K e m p (3) a t o m i z e d n e u t r a l p o t a s s i u m i o d i d e m e t h o d a n d


64


also w i t h t h e m o d i f i e d u l t r a v i o l e t a b s o r p t i o n m e t h o d of S t a i r (29). T h e r e s u l t s of a l l t h r e e m e t h o d s w e r e i n g o o d a g r e e m e n t a t a c o n c e n t r a t i o n of a b o u t 1 p . p . m . b y w e i g h t . T h e a l k a l i n e p o t a s s i u m i o d i d e m e t h o d of S m i t h a n d D i a m o n d (27) c o n s i s t e n t l y gave low results. T h e m e t h o d u s e d t o d e t e r m i n e t h e r e l a t i v e a m o u n t s of ozone f r o m v a r i o u s t y p e s of S t e r i l a m p t u b e s s h o w n i n T a b l e I w a s t h a t of C r a b t r e e a n d K e m p (3). T h e l a m p s T a b l e I.

Concentration of O z o n e from A v e r a g e Sterilamp O p e r a t e d at Optimum Conditions


Sterilamp 794-H (Odorout) 794 782-H-30 782-H-10 G36 T6-H»

Application Examples Room, office Domestic refrigerator Large refrigerators Hot air furnaces Air-conditioning ducts

Wattage 3.5 3.5 17.0 12.0 39.0

Ozone per 1000 C u . F t . , P . P . M . by Wt. 0.05 0.02 0.42 0.15 2.10

» L type of Sterilamp transmits about one tenth to one fiftieth of the 1849-A. radia tion as the H type.

were h u n g i n a b o u t t h e g e o m e t r i c a l c e n t e r of a s m a l l v a c a n t r o o m of 1780 c u b i c feet. T h e relative h u m i d i t y was between 20 a n d 3 0 % a t 70° to 75° F . F i g u r e 7 shows t h a t ,

"5

Π)

Distance

Έθ

in Inches f r o m

25

30

Sterilamp

Figure 7. Transmittance of radiation below 2000 through air at various relative humidities

A.


N A G Y — C O N T R O L OF MOLD, BACTERIA, ODORS

65

w i t h t h e a v a i l a b l e r a y l e n g t h a n d h u m i d i t y , n e a r l y a l l of t h e 1 8 4 9 - A . r a d i a t i o n g e n e r a t e d b y t h e l a m p w a s a b s o r b e d b y t h e o x y g e n of t h e a i r , a n d t h e m a x i m u m a m o u n t of ozone w o u l d be e x p e c t e d . O p e r a t i n g these l a m p s i n enclosed f i x t u r e s , a i r d u c t s , a t l o w e r t e m p e r a t u r e s , o r a t h i g h e r h u m i d i t y w i l l decrease t h e a m o u n t of ozone g e n e r a t e d . I n a c t u a l i n s t a l l a t i o n s o n l y a b o u t one t e n t h of t h e c o n c e n t r a t i o n g i v e n i n T a b l e I w i l l b e f o u n d . T a b l e I is a m e a s u r e of t h e r e l a t i v e p r o p o r t i o n of ozone g e n e r a t e d b y t h e various lamps. T h e r e l a t i v e a m o u n t of ozone g e n e r a t e d b y v a r i o u s u l t r a v i o l e t l a m p s c a n b e a s c e r t a i n e d b y t h e m e a s u r e m e n t of t h e r a d i a t i o n e m i t t e d b e l o w 2000 A . A 789 p h o t o t u b e , w h i c h w i l l r e s p o n d o n l y t o these s h o r t r a d i a t i o n s , h a s b e e n u s e d f o r s u c h c o m p a r i s o n s a n d f o r c o n t r o l of t h e q u a l i t y of glass i n t h e p r o d u c t i o n of t h e l a m p s .


Literature (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30) (31) (32)

Cited

Christensen, P. B., Refrig. Engr. 39, 296-9 (1940). Colbert, J. W., Ibid., 60, 265-7 (1952). Crabtree, J., Kemp, A. R., Ind. Eng. Chem., Anal. Ed. 18, 769-74 (1946). Davidson, G., Travis, J. H., Psychiat. Quart., Suppl. 27, 90-1 (1953). Dingle, W. M., Gage, J. C., Brit. J. Ind. Med. 11, 140-4 (1954). Elford, W. J., Van den Ende, J., J. Hyg. 42, 240-65 (1942). Ewell, A. W., Am. Soc. Refrig. Engr. 41, 331-4 (1941). Ibid., 55, 466-8 (1948). Ewell, A. W., J. Appl. Phys. 13, 759-67 (1942). Ibid., 17, 908-11 (1946). Ewell, A. W., Refrig. Data Book 2 (1940). Ibid., Chap. 18, 143-99 (1946). Ewell, A. W., Refrig. Engr. 50, 523-4, 560-1 (1945). Ibid., 58, 1-4, Sect. 2 (1950). Gee, A. H., Ellner, P. D., Stevens, M. R., U. S. Air Force Tech. Rept. 6565, P t . 3 (1953). Gross, C. R., Smock, R. M., Refrig. Engr. 50, 535-40 (1945). Hart, D., A.M.A. Arch. Surg. 37, 956-72 (1938). Hart, D., "Airborne Infections in Clean Operative Wounds," Proc. of Interstate Post Graduate Medical Assembly North America, Oct. 17-20, 1944, Chicago, Ill. James, R. F. (to Westinghouse Electric Corp.), U. S. Patent 2,192,348 (March 5, 1940). Mallmann, W. L., Churchill, E. S., Refrig. Engr. 51, 523-8 (1946). Nagy, R., Baker's Dig. 22, 25-6 (1948). Nagy, R., Mouromseff, G., Rixton, F. H., Heating, Piping, Air Conditioning 26, 82-7 (1954). Nagy, R., Rentschler, H. C. (to Westinghouse Electric Corp), U. S. Patent 2,337,507 (Jan. 18, 1944). Rentschler, H. C., Nagy, R., J. Bacteriol. 44, 85-94 (1942). Rentschler, H. C., Nagy, R., Mouromseff, G., Ibid., 41, 745-74 (1941). Schrenk, H. H., Ind. Eng. Chem. 47, N o . 93A (February 1955). Smith, R. G., Diamond, P., Ind. Hyg. Quart. 13, 235-8 (1952). Smock, R. M., Watson, R. D., J. Am. Soc. Refrig. Engr. 42, 97-101 (1941). Stair, R., Bagg, T. C., Johnson, R. G., J. Research Natl. Bur. Standards 54, 133-9 (1954). Summer, W., Mfg. Chemist 24, 105-10 (1953). Watson, R. D., J. Am. Soc. Refrig. Engr. 46, 103-6 (1943). Wedum, A. G., Hanel, E., Phillips, G. B., Public Health Rept. 71, 331-6 (1956). R E C E I V E D for review March 27, 1957.

Accepted June 19. 1957.


ozone chemistry and technology - ACS Publications

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