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Vacuum technique
VACUUM Classifie d A b s t r a c t s
I --
I0 --
General
VACUUM
Science
and Engineering
ENGINEERING
(GENERAL)
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--
I
Abskraot. No
#ndRefere~0o s
xo
V a c u u m E d u c a t i o n in the United States United States. T r a i n i n g in v a c u u m t e c h n o l o g y in t h e U.S.A. is discussed, t a k i n g into c o n s i d e r a t i o n universities, i n d u s t r i e s u s i n g v a c u u m processes, v a c u u m e q u i p m e n t m a n u f a c t u r e r s , i n d u s t r i a l r e s e a r c h laboratories, A t o m i c E n e r g y C o m m i s s i o n i n s t a l l a t i o n s a n d laboratories o p e r a t e d b y t h e U.S. G o v e r n m e n t . T h e m o s t wide-spread m e t h o d of t r a i n i n g is of t h e o n - t h e - j o b variety, i n v o l v i n g w o r k i n g w i t h v a c u u m e q u i p m e n t a n d w i t h m o r e e x p e r i e n c e d personnel, t h e use of i n f o r m a l conferences a n d t h e use of t h e t e c h n i c a l literature. Complete c o u r s e s of i n s t r u c t i o n in v a c u u m technology, in universities or i n d u s t r y , are q u i t e rare. T h e f o r m a t i o n of t h e C o m m i t t e e on V a c u u m T e c h n i q u e s , Inc., is discussed briefly. I t is e x p e c t e d t h a t v a c u u m processes will be u s e d m o r e a n d m o r e widely in t h e f u t u r e . However, it is believed t h a t t h e o n - t h e - j o b t y p e of t r a i n i n g will still r e m a i n t h e basic m e t h o d . I t is v e r y u n l i k e l y t h a t courses in v a c u u m t e c h n o l o g y will be offered in t h e r e g u l a r u n i v e r s i t y curricula. T h e t r e n d will p r o b a b l y be t o w a r d t h e i n t r o d u c t i o n of s u c h courses in u n i v e r s i t y e x t e n s i o n s y s t e m s . (Author) Vacuum Technique France. Tables, e x t e n d i n g over 4 pages, give d a t a of t h e m e c h a n i c a l r o t a r y a n d oil diffusion p u m p s p r o d u c e d b y t h e leading v a c u u m e q u i p m e n t m a n u f a c t u r e r s in France, U n i t e d States, G r e a t Britain, G e r m a n y , Italy, S w i t z e r l a n d a n d Liechtenstein. T h e d a t a refers to t h e n u m b e r of stages, speeds, u l t i m a t e p r e s s u r e s obtainable, p o w e r c o n s u m p t i o n , etc. I t follows i n f o r m a t i o n of i n t e r e s t to t h e design engineer c o n c e r n e d with t h e c o n s t r u c tion of c o m p l e t e v a c u u m installations and, finally, a discussion is a d d e d on suitable p u m p i n g fluids, joints, stopcocks, v a l v e s a n d seals.
1/i
Article by A. Guthrie Vavuum 5, October 1955 5-24
2/I Article by R. Dor6, In~en. Tech. september 1956 79-89
Mechanical Vacuum Pumps See A b s t r a c t No.: 2/II
3/1
Vapour Pumping Characteristics of Gas Ballast Pumps United Kingdom. T h e m e c h a n i s m of c o n t a m i n a t i o n w h e n v a p o u r s are p u m p e d b y oil-sealed r o t a r y p u m p s is described a n d a m e t h o d is discussed for calculating t h e degree of p r o t e c t i o n afforded b y g a s b a l l a s t in t e r m s of t h e m a x i m u m m a s s flow rate a t w h i c h off-insoluble v a p o u r s c a n be p u m p e d w i t h o u t significant c o n d e n s a t i o n of v a p o u r in t h e p u m p . I t is s h o w n e x p e r i m e n t a l l y t h a t , t h o u g h this calculated m a x i m u m flow rate does c o r r e s p o n d a p p r o x i m a t e l y to t h e practical limit for no c o n d e n s a t i o n , it can often be g r e a t l y exceeded w i t h o u t c u m u l a t i v e c o n t a m i n a t i o n or serious i m p a i r m e n t of p u m p p e r f o r m a n c e . T h e s o m e w h a t different characteristics w h e n p u m p i n g oil-soluble v a p o u r s are discussed a n d illustrated b y e x p e r i m e n t a l results, a n d it is c o n c l u d e d t h a t , a l t h o u g h gas b a l l a s t c a n g e n e r a l l y provide considerable protection in s u c h cases, a h i g h proportion of t h e v o l u m e t r i c a n d m a s s p u m p i n g r a t e s theoretically possible on t h e basis of p u m p d i s p l a c e m e n t is m o r e likely to be achieved in larger a n d h o t t e r - r u n n i n g t h a n in smaller a n d cooler-running p u m p s .
4/I
Vapour and Molecular Pumps Germany. Diffusion p u m p s , v a p o u r b o o s t e r p u m p s , t h e molecular p u m p , t h e i o n - p u m p a n d m e t h o d s of reducing t h e gas p r e s s u r e in t h e vessel sealed off after p u m p i n g are discussed. T h e special f e a t u r e s d i s t i n g u i s h i n g t h e o p e r a t i n g principle of t h e v a p o u r - b o o s t e r p u m p a n d t h a t of t h e diffusion p u m p are described in detail. Generally, t h e diffusion p u m p s h a v e t h e i r h i g h e s t p u m p i n g speeds in t h e p r e s s u r e r a n g e below 10 -8 m m . H g a n d t h e v a p o u r b o o s t e r p u m p s are designed to give t h e h i g h e s t speeds a t t h e level of a b o u t 10 -1 m m . Hg. T h e c o m p a r a t i v e m e r i t s of v a r i o u s p u m p fluids s u c h as m e r c u r y a n d t e t r a c h l o r d i p h e n y l are considered. B a c k s t r e a m i n g of t h e p u m p fluid c a n be reduced to a m i n i m u m b y suitable m e a n s . I n s o m e cases, for i n s t a n c e in v a c u u m i m p r e g n a t i o n , cont a m i n a t i o n of t h e i m p r e g n a t i n g m a t e r i a l c a n be a v o i d e d b y o p e r a t i n g t h e diffusion p u m p w i t h t h e i m p r e g n a t i n g m a t e r i a l itself as t h e p u m p fluid. T h e m o l e c u l a r p u m p , first p r o p o s e d b y Gaede in 1909, is a m e c h a n i c a l p u m p . O p e r a t i n g w i t h a b a c k i n g pressure of 0.1 m m . Hg, it m a y r e a c h a n u l t i m a t e of 10 -s m m . H g a n d h a s a speed of 8 litre p e r second a t a p r e s s u r e of 10 -8 ram. Hg. D u e to t h e o p e r a t i n g principle of t h e p u m p t h e p r o b l e m of b a c k s t r e a m i n g of c o n t a m i n a t i n g v a p o u r s is a b s e n t . T h e p u m p is e m p l o y e d for t h e e v a c u a t i o n of c a t h o d e - r a y oscilloscopes a n d electron microscopes. T h e latest t y p e of p u m p is t h e i o n - p u m p w h e r e t h e gases to be p u m p e d are ionised a n d t h e ions collecting in t h e c a t h o d e space are r e m o v e d b y m e a n s of a diffusion p u m p . T h i s t y p e of p u m p , too, p r o d u c e s a 'clean' v a c u u m . I t reaches u l t i m a t e s of 10 -11 m m . H g a n d its speed is c o m p a r a b l e to t h a t of diffusion p u m p s . I t s d i s a d v a n t a g e is a h i g h power c o n s u m p t i o n . T h e article concludes w i t h r e m a r k s on t h e g e t t e r i n g process applied w h e n t h e e v a c u a t e d vessel h a s been sealed off, a n d t h e description of a m e t h o d of m e a s u r i n g t h e speed of v a c u u m p u m p s generally.
October, 1956
Vacuum Vol. V1
Article by B. D. Power & R. A. Kenna Vac~u~
5, October 1955 35-58
5/I
Article by P. Hochh~usler Elektrotech. Z. z7, 21.11.1955 417-423
183
I --
I0 --
General
VACUUM
Science
and Engineering
ENGINEERING
(GENERAL)
--
--
I
Abskraot. No
#ndRefere~0o s
xo
V a c u u m E d u c a t i o n in the United States United States. T r a i n i n g in v a c u u m t e c h n o l o g y in t h e U.S.A. is discussed, t a k i n g into c o n s i d e r a t i o n universities, i n d u s t r i e s u s i n g v a c u u m processes, v a c u u m e q u i p m e n t m a n u f a c t u r e r s , i n d u s t r i a l r e s e a r c h laboratories, A t o m i c E n e r g y C o m m i s s i o n i n s t a l l a t i o n s a n d laboratories o p e r a t e d b y t h e U.S. G o v e r n m e n t . T h e m o s t wide-spread m e t h o d of t r a i n i n g is of t h e o n - t h e - j o b variety, i n v o l v i n g w o r k i n g w i t h v a c u u m e q u i p m e n t a n d w i t h m o r e e x p e r i e n c e d personnel, t h e use of i n f o r m a l conferences a n d t h e use of t h e t e c h n i c a l literature. Complete c o u r s e s of i n s t r u c t i o n in v a c u u m technology, in universities or i n d u s t r y , are q u i t e rare. T h e f o r m a t i o n of t h e C o m m i t t e e on V a c u u m T e c h n i q u e s , Inc., is discussed briefly. I t is e x p e c t e d t h a t v a c u u m processes will be u s e d m o r e a n d m o r e widely in t h e f u t u r e . However, it is believed t h a t t h e o n - t h e - j o b t y p e of t r a i n i n g will still r e m a i n t h e basic m e t h o d . I t is v e r y u n l i k e l y t h a t courses in v a c u u m t e c h n o l o g y will be offered in t h e r e g u l a r u n i v e r s i t y curricula. T h e t r e n d will p r o b a b l y be t o w a r d t h e i n t r o d u c t i o n of s u c h courses in u n i v e r s i t y e x t e n s i o n s y s t e m s . (Author) Vacuum Technique France. Tables, e x t e n d i n g over 4 pages, give d a t a of t h e m e c h a n i c a l r o t a r y a n d oil diffusion p u m p s p r o d u c e d b y t h e leading v a c u u m e q u i p m e n t m a n u f a c t u r e r s in France, U n i t e d States, G r e a t Britain, G e r m a n y , Italy, S w i t z e r l a n d a n d Liechtenstein. T h e d a t a refers to t h e n u m b e r of stages, speeds, u l t i m a t e p r e s s u r e s obtainable, p o w e r c o n s u m p t i o n , etc. I t follows i n f o r m a t i o n of i n t e r e s t to t h e design engineer c o n c e r n e d with t h e c o n s t r u c tion of c o m p l e t e v a c u u m installations and, finally, a discussion is a d d e d on suitable p u m p i n g fluids, joints, stopcocks, v a l v e s a n d seals.
1/i
Article by A. Guthrie Vavuum 5, October 1955 5-24
2/I Article by R. Dor6, In~en. Tech. september 1956 79-89
Mechanical Vacuum Pumps See A b s t r a c t No.: 2/II
3/1
Vapour Pumping Characteristics of Gas Ballast Pumps United Kingdom. T h e m e c h a n i s m of c o n t a m i n a t i o n w h e n v a p o u r s are p u m p e d b y oil-sealed r o t a r y p u m p s is described a n d a m e t h o d is discussed for calculating t h e degree of p r o t e c t i o n afforded b y g a s b a l l a s t in t e r m s of t h e m a x i m u m m a s s flow rate a t w h i c h off-insoluble v a p o u r s c a n be p u m p e d w i t h o u t significant c o n d e n s a t i o n of v a p o u r in t h e p u m p . I t is s h o w n e x p e r i m e n t a l l y t h a t , t h o u g h this calculated m a x i m u m flow rate does c o r r e s p o n d a p p r o x i m a t e l y to t h e practical limit for no c o n d e n s a t i o n , it can often be g r e a t l y exceeded w i t h o u t c u m u l a t i v e c o n t a m i n a t i o n or serious i m p a i r m e n t of p u m p p e r f o r m a n c e . T h e s o m e w h a t different characteristics w h e n p u m p i n g oil-soluble v a p o u r s are discussed a n d illustrated b y e x p e r i m e n t a l results, a n d it is c o n c l u d e d t h a t , a l t h o u g h gas b a l l a s t c a n g e n e r a l l y provide considerable protection in s u c h cases, a h i g h proportion of t h e v o l u m e t r i c a n d m a s s p u m p i n g r a t e s theoretically possible on t h e basis of p u m p d i s p l a c e m e n t is m o r e likely to be achieved in larger a n d h o t t e r - r u n n i n g t h a n in smaller a n d cooler-running p u m p s .
4/I
Vapour and Molecular Pumps Germany. Diffusion p u m p s , v a p o u r b o o s t e r p u m p s , t h e molecular p u m p , t h e i o n - p u m p a n d m e t h o d s of reducing t h e gas p r e s s u r e in t h e vessel sealed off after p u m p i n g are discussed. T h e special f e a t u r e s d i s t i n g u i s h i n g t h e o p e r a t i n g principle of t h e v a p o u r - b o o s t e r p u m p a n d t h a t of t h e diffusion p u m p are described in detail. Generally, t h e diffusion p u m p s h a v e t h e i r h i g h e s t p u m p i n g speeds in t h e p r e s s u r e r a n g e below 10 -8 m m . H g a n d t h e v a p o u r b o o s t e r p u m p s are designed to give t h e h i g h e s t speeds a t t h e level of a b o u t 10 -1 m m . Hg. T h e c o m p a r a t i v e m e r i t s of v a r i o u s p u m p fluids s u c h as m e r c u r y a n d t e t r a c h l o r d i p h e n y l are considered. B a c k s t r e a m i n g of t h e p u m p fluid c a n be reduced to a m i n i m u m b y suitable m e a n s . I n s o m e cases, for i n s t a n c e in v a c u u m i m p r e g n a t i o n , cont a m i n a t i o n of t h e i m p r e g n a t i n g m a t e r i a l c a n be a v o i d e d b y o p e r a t i n g t h e diffusion p u m p w i t h t h e i m p r e g n a t i n g m a t e r i a l itself as t h e p u m p fluid. T h e m o l e c u l a r p u m p , first p r o p o s e d b y Gaede in 1909, is a m e c h a n i c a l p u m p . O p e r a t i n g w i t h a b a c k i n g pressure of 0.1 m m . Hg, it m a y r e a c h a n u l t i m a t e of 10 -s m m . H g a n d h a s a speed of 8 litre p e r second a t a p r e s s u r e of 10 -8 ram. Hg. D u e to t h e o p e r a t i n g principle of t h e p u m p t h e p r o b l e m of b a c k s t r e a m i n g of c o n t a m i n a t i n g v a p o u r s is a b s e n t . T h e p u m p is e m p l o y e d for t h e e v a c u a t i o n of c a t h o d e - r a y oscilloscopes a n d electron microscopes. T h e latest t y p e of p u m p is t h e i o n - p u m p w h e r e t h e gases to be p u m p e d are ionised a n d t h e ions collecting in t h e c a t h o d e space are r e m o v e d b y m e a n s of a diffusion p u m p . T h i s t y p e of p u m p , too, p r o d u c e s a 'clean' v a c u u m . I t reaches u l t i m a t e s of 10 -11 m m . H g a n d its speed is c o m p a r a b l e to t h a t of diffusion p u m p s . I t s d i s a d v a n t a g e is a h i g h power c o n s u m p t i o n . T h e article concludes w i t h r e m a r k s on t h e g e t t e r i n g process applied w h e n t h e e v a c u a t e d vessel h a s been sealed off, a n d t h e description of a m e t h o d of m e a s u r i n g t h e speed of v a c u u m p u m p s generally.
October, 1956
Vacuum Vol. V1
Article by B. D. Power & R. A. Kenna Vac~u~
5, October 1955 35-58
5/I
Article by P. Hochh~usler Elektrotech. Z. z7, 21.11.1955 417-423
183