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Mechanical vacuum pumps
VACUUM Classified A b s t r a c t s
I I --
Vacuum
Apparatus
20 - -
PUMPS
and
--
Auxiliaries
--
II
Abstract No. and References
20
V a c u u m Technique See A b s t r a c t No.: 2/I
1/II
Mechanical Vacuum Pumps
2/II
Germany. T h e a u t h o r reviews r e c e n t design d e v e l o p m e n t in t h e field of m e c h a n i c a l v a c u u m p u m p s . P a r t i c u l a r reference is m a d e to t h e operational a n d economical conditions w i t h r e s p e c t to gas b a l l a s t p u m p s a n d certain t y p e s of t h e s a m e fitted w i t h a u t o m a t i c oil d e c o n t a m i n a t i o n e q u i p m e n t . P u m p i n g c o m b i n a t i o n s u s i n g t h e R o o t s p u m p as t h e h i g h v a c u u m p u m p are also discussed a n d are p a r t i c u l a r l y useful for large t h r o u g h p u t s in t h e region a b o v e 100 m3./hour.
Improvements i.o.r.t. Rotary Vacuum P u m p s
Article by H. Bfirger Chem. Technik 8, April 1956 218-232
3/II
United States. I n r o t a r y v a c u u m p u m p s of t h e t w o - s t a g e t y p e t h e rotors of t h e two stages are n o r m a l l y m o u n t e d on a c o m m o n s h a f t in a single c a s t housing, a n d t h e centre wall w h i c h s e p a r a t e s t h e m is m a c h i n e d on b o t h sides. T h e m a c h i n i n g o p e r a t i o n r e m o v e s t h e surface skin f r o m t h e c a s t faces, a n d it is often f o u n d t h a t t h e m e t a l t h u s e x p o s e d is sufficiently p o r o u s to lead to appreciable i n t e r - s t a g e leakage. I n t h i s design t h e centre wall is replaced b y a partition, left hollow b y coring d u r i n g casting, so t h a t at least one u n b r o k e n skin is m a i n t a i n e d b e t w e e n its m a c h i n e d faces. T h i s skin is practically i m p e r v i o u s to t h e v a p o u r s p u m p e d . T h e hollow so f o r m e d is divided into t w o c h a m b e r s b y a web, w h i c h h a s a t its centre a h u b c a r r y i n g t h e s h a f t bearing. T h e h u b is t h e only p a r t of t h e p a r t i t i o n n o t h a v i n g a n u n b r o k e n skin, b u t is long e n o u g h axially to p r e v e n t leakage. O n e of t h e c h a m b e r s is m a d e to serve as t h e i n t e r - s t a g e t r a n s f e r d u c t a n d also as t h e first s t a g e oil reservoir, f r o m w h i c h oil is distrib u t e d t h r o u g h suitable c h a n n e l s to b o t h t h e c e n t r e b e a r i n g a n d to t h e m o v i n g p a r t s of t h e first stage. T h i s position of t h e s h a f t b e a r i n g enables t h e bearing, u s u a l l y p r o v i d e d in t h e o u t e r e n d cover of t h e first stage, to be d i s p e n s e d w i t h
g . G. Bowering & New York Air Brake Co. Brit. Pat. 739-824
4/i1
Improvements in Rotary Pumps or Compressors United Kingdom. A novel design of r o t a r y p u m p is described w h i c h a i m s (a) a t r e d u c i n g wear a n d t e a r p r o d u c e d b e t w e e n t h e blades on one h a n d a n d t h e r o t o r on t h e other, a n d (b) a t r e d u c i n g t h e noise c a u s e d b y vibration. T h e n e w design provides for each of t h e t w o blades to be of a d e p t h g r e a t e r t h a n t h e m a x i m u m d i a m e t e r of t h e r o t o r a n d to be positioned in t h e c o n v e n t i o n a l r o t o r slot on t o p of each o t h e r in s u c h a m a n n e r , t h a t t h e a p e r t u r e s p r o v i d e d in t h e central p o r t i o n of e a c h blade overlap a n d t h a t s p r i n g s a c c o m m o d a t e d in t h e s e a p e r t u r e s exercise t h e n e c e s s a r y t h r u s t in t h e required opposite directions for t h e blades to m a k e a n d keep c o n t a c t w i t h t h e s t a t o r surface. I n addition, t h e surface of t h e s t a r e r casing is f o r m e d w i t h a profile c o m p r i s i n g t w o circular arcs of t h e s a m e r a d i u s c e n t r e d a t p o i n t s s i t u a t e d s y m m e t r i c a l l y on opposite sides of t h e d i a m e t e r of t h e r o t o r p a s s i n g t h r o u g h t h e location of e n g a g e m e n t of t h e rotor w i t h t h e s t a r e r surface, w h i c h arcs are joined b y t w o circular arcs of t h e s a m e r a d i u s c e n t r e d on t h e d i a m e t e r in question.
MetropolitanVickers Electrical Co. Ltd. Brit. Pat. 739-334
F o u r P r o b l e m s Regarding the Amount of Air Displaced b y a Compressor or a Rotary P u m p Rumania. A n expression for t h e air displaced b y a c o m p r e s s o r or r o t a r y p u m p is developed a n d t h e influence of t h e t h i c k n e s s of t h e v a n e s , t h e i r a n g u l a r position a n d t h e size of t h e c o m p r e s s e d angle on t h e d i s p l a c e m e n t s h a s b e e n investigated. (Author)
5/II Article by C. Buda Bull. Ir~t. Polit. No.l-2, 1955 325-335
Vapour Pumping Characteristics of Gas Ballast Pumps
6/11
See A b s t r a c t No.: 4/I
Improvements i.o.r.t. High-Vacuum Pump Systems
7/II
United Kingdom. I n t w o - s t a g e r o t a r y v a c u u m p u m p s y s t e m s e m p l o y i n g a sealing fluid, s u c h as oil, t h e l a t t e r f r e q u e n t l y b e c o m e s c o n t a m i n a t e d w i t h s u b s t a n c e s of a h i g h v a p o u r pressure, c a u s i n g liquefaction of t h e c o n t a m i n a n t s a n d c o n s e q u e n t r e d u c t i o n in p u m p i n g efficiency. T h e i m p u r i t e s m a y be r e m o v e d f r o m t h e oil b y i n t e r p o s i n g a s e p a r a t o r t a n k of c o n v e n t i o n a l design b e t w e e n t h e t w o stages a n d f r a c t l o n a t l n g t h e c o n t a m i n a n t s b y e v a p o r a t i o n . T h e fluid is circulated t h r o u g h t h e s e p a r a t o r b y m e a n s of a p u m p fitted w i t h a n o n - r e t u r n spring-loaded valve.
s/Ix
Improvements r.t. Vacuum Pumps United Kingdom. A n a d a p t o r is described w h i c h c a n be fitted to t h e o u t l e t of a r o t a r y p u m p , o p e r a t i n g in air, so as to direct t h e e x h a u s t s t r e a m of g a s to flow over t h e b o d y of t h e p u m p . T h e device is to s e r v e as a silencer, a n d essentially consists of a pipe screwed into t h e e x h a u s t o u t l e t a n d leading to a hood, closed a t one e n d concentric w i t h t h e pipe a n d h a v i n g a series of o u t l e t s r o u n d t h e e n d n e a r e s t t h e p u m p body, T h e s e o u t l e t s direct t h e s t r e a m of e x h a u s t gas so as to p r o d u c e a cooling effect on t h e p u m p .
October, 1956
H. Smethurst & General Engineering Co. (Radcliffe) Ltd. Brit. Pat. 754,963
Vacuum Vol. V I
T. L. Clark & Alfa-Laval Co. Ltd. Brit. Pat. 754,333
237
I I --
Vacuum
Apparatus
20 - -
PUMPS
and
--
Auxiliaries
--
II
Abstract No. and References
20
V a c u u m Technique See A b s t r a c t No.: 2/I
1/II
Mechanical Vacuum Pumps
2/II
Germany. T h e a u t h o r reviews r e c e n t design d e v e l o p m e n t in t h e field of m e c h a n i c a l v a c u u m p u m p s . P a r t i c u l a r reference is m a d e to t h e operational a n d economical conditions w i t h r e s p e c t to gas b a l l a s t p u m p s a n d certain t y p e s of t h e s a m e fitted w i t h a u t o m a t i c oil d e c o n t a m i n a t i o n e q u i p m e n t . P u m p i n g c o m b i n a t i o n s u s i n g t h e R o o t s p u m p as t h e h i g h v a c u u m p u m p are also discussed a n d are p a r t i c u l a r l y useful for large t h r o u g h p u t s in t h e region a b o v e 100 m3./hour.
Improvements i.o.r.t. Rotary Vacuum P u m p s
Article by H. Bfirger Chem. Technik 8, April 1956 218-232
3/II
United States. I n r o t a r y v a c u u m p u m p s of t h e t w o - s t a g e t y p e t h e rotors of t h e two stages are n o r m a l l y m o u n t e d on a c o m m o n s h a f t in a single c a s t housing, a n d t h e centre wall w h i c h s e p a r a t e s t h e m is m a c h i n e d on b o t h sides. T h e m a c h i n i n g o p e r a t i o n r e m o v e s t h e surface skin f r o m t h e c a s t faces, a n d it is often f o u n d t h a t t h e m e t a l t h u s e x p o s e d is sufficiently p o r o u s to lead to appreciable i n t e r - s t a g e leakage. I n t h i s design t h e centre wall is replaced b y a partition, left hollow b y coring d u r i n g casting, so t h a t at least one u n b r o k e n skin is m a i n t a i n e d b e t w e e n its m a c h i n e d faces. T h i s skin is practically i m p e r v i o u s to t h e v a p o u r s p u m p e d . T h e hollow so f o r m e d is divided into t w o c h a m b e r s b y a web, w h i c h h a s a t its centre a h u b c a r r y i n g t h e s h a f t bearing. T h e h u b is t h e only p a r t of t h e p a r t i t i o n n o t h a v i n g a n u n b r o k e n skin, b u t is long e n o u g h axially to p r e v e n t leakage. O n e of t h e c h a m b e r s is m a d e to serve as t h e i n t e r - s t a g e t r a n s f e r d u c t a n d also as t h e first s t a g e oil reservoir, f r o m w h i c h oil is distrib u t e d t h r o u g h suitable c h a n n e l s to b o t h t h e c e n t r e b e a r i n g a n d to t h e m o v i n g p a r t s of t h e first stage. T h i s position of t h e s h a f t b e a r i n g enables t h e bearing, u s u a l l y p r o v i d e d in t h e o u t e r e n d cover of t h e first stage, to be d i s p e n s e d w i t h
g . G. Bowering & New York Air Brake Co. Brit. Pat. 739-824
4/i1
Improvements in Rotary Pumps or Compressors United Kingdom. A novel design of r o t a r y p u m p is described w h i c h a i m s (a) a t r e d u c i n g wear a n d t e a r p r o d u c e d b e t w e e n t h e blades on one h a n d a n d t h e r o t o r on t h e other, a n d (b) a t r e d u c i n g t h e noise c a u s e d b y vibration. T h e n e w design provides for each of t h e t w o blades to be of a d e p t h g r e a t e r t h a n t h e m a x i m u m d i a m e t e r of t h e r o t o r a n d to be positioned in t h e c o n v e n t i o n a l r o t o r slot on t o p of each o t h e r in s u c h a m a n n e r , t h a t t h e a p e r t u r e s p r o v i d e d in t h e central p o r t i o n of e a c h blade overlap a n d t h a t s p r i n g s a c c o m m o d a t e d in t h e s e a p e r t u r e s exercise t h e n e c e s s a r y t h r u s t in t h e required opposite directions for t h e blades to m a k e a n d keep c o n t a c t w i t h t h e s t a t o r surface. I n addition, t h e surface of t h e s t a r e r casing is f o r m e d w i t h a profile c o m p r i s i n g t w o circular arcs of t h e s a m e r a d i u s c e n t r e d a t p o i n t s s i t u a t e d s y m m e t r i c a l l y on opposite sides of t h e d i a m e t e r of t h e r o t o r p a s s i n g t h r o u g h t h e location of e n g a g e m e n t of t h e rotor w i t h t h e s t a r e r surface, w h i c h arcs are joined b y t w o circular arcs of t h e s a m e r a d i u s c e n t r e d on t h e d i a m e t e r in question.
MetropolitanVickers Electrical Co. Ltd. Brit. Pat. 739-334
F o u r P r o b l e m s Regarding the Amount of Air Displaced b y a Compressor or a Rotary P u m p Rumania. A n expression for t h e air displaced b y a c o m p r e s s o r or r o t a r y p u m p is developed a n d t h e influence of t h e t h i c k n e s s of t h e v a n e s , t h e i r a n g u l a r position a n d t h e size of t h e c o m p r e s s e d angle on t h e d i s p l a c e m e n t s h a s b e e n investigated. (Author)
5/II Article by C. Buda Bull. Ir~t. Polit. No.l-2, 1955 325-335
Vapour Pumping Characteristics of Gas Ballast Pumps
6/11
See A b s t r a c t No.: 4/I
Improvements i.o.r.t. High-Vacuum Pump Systems
7/II
United Kingdom. I n t w o - s t a g e r o t a r y v a c u u m p u m p s y s t e m s e m p l o y i n g a sealing fluid, s u c h as oil, t h e l a t t e r f r e q u e n t l y b e c o m e s c o n t a m i n a t e d w i t h s u b s t a n c e s of a h i g h v a p o u r pressure, c a u s i n g liquefaction of t h e c o n t a m i n a n t s a n d c o n s e q u e n t r e d u c t i o n in p u m p i n g efficiency. T h e i m p u r i t e s m a y be r e m o v e d f r o m t h e oil b y i n t e r p o s i n g a s e p a r a t o r t a n k of c o n v e n t i o n a l design b e t w e e n t h e t w o stages a n d f r a c t l o n a t l n g t h e c o n t a m i n a n t s b y e v a p o r a t i o n . T h e fluid is circulated t h r o u g h t h e s e p a r a t o r b y m e a n s of a p u m p fitted w i t h a n o n - r e t u r n spring-loaded valve.
s/Ix
Improvements r.t. Vacuum Pumps United Kingdom. A n a d a p t o r is described w h i c h c a n be fitted to t h e o u t l e t of a r o t a r y p u m p , o p e r a t i n g in air, so as to direct t h e e x h a u s t s t r e a m of g a s to flow over t h e b o d y of t h e p u m p . T h e device is to s e r v e as a silencer, a n d essentially consists of a pipe screwed into t h e e x h a u s t o u t l e t a n d leading to a hood, closed a t one e n d concentric w i t h t h e pipe a n d h a v i n g a series of o u t l e t s r o u n d t h e e n d n e a r e s t t h e p u m p body, T h e s e o u t l e t s direct t h e s t r e a m of e x h a u s t gas so as to p r o d u c e a cooling effect on t h e p u m p .
October, 1956
H. Smethurst & General Engineering Co. (Radcliffe) Ltd. Brit. Pat. 754,963
Vacuum Vol. V I
T. L. Clark & Alfa-Laval Co. Ltd. Brit. Pat. 754,333
237