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Isolation valves for vacuum systems
VACUUM Classified A b s t r a c t s
II - -
Vacuum
Apparatus
and
Auxiliaries
--
II
Contd.
A Replica Technique in the Study of Chemical Precipitation Processes United States. Vehere precipitates formed b y mixing solutions of chemical reagents are to be studied in tile electron microscope the use of replica techniques is preferable to a direct e x a m i n a t i o n of the specimen. If exposed to the electron b e a m the genuine specimen material tends to decompose or to be c o n t a m i n a t e d b y residual gases in the chamber. F i s c h b e i n developed a 3 - s t e p wet replication process for use w i t h biological specimens. The process described in the p r e s e n t article is a 1-step replication process based on Fischbein's technique. A sandwich is prepared consisting of 2 glass slides holding a drop of the m o t h e r liquid w i t h the precipitate in suspension between them. One of the glass slides is covered w i t h a film of parlodion. A parlodion film of suitable thickness is obtained b y dipping the glass slide into a 3% parlodion solution ill a m y l acetate and s u b s e q u e n t l y drying it. The 2 glass slides are clamped together and the sandwich is heated in the m o t h e r liquid at boiling p o i n t t e m p e r a t u r e for 10 minutes. The sandwich is t h e n t a k e n apart, the precipitate dissolved, the replica floated off the glass slide on w a t e r and picked u p b y screens in the conventional way. I n order to obtain good c o n t r a s t shadowing is essential. The m o s t suitable angle for shadowing was found to be 30 ° . Micrographs of directly viewed specimens and replicas of the same material, e.g. silver clfloride particles, are s h o w n in illustrations. Sommaire : Une nouvelle m6thode de r6plique bas6 sur la in6thode de r6plique h u m i d e de Fischbein des sp6cimens biologiques est d6crite.
Abstract No. and References
157/II
Article by R. B. Fischer & J. P. Ellinger J. AppL Phys. 24, Aug. 1953 1051-1053
O Microstructure of Capacitor Paper
158/1I
See A b s t r a c t No. : 209/I
An Electron-Micrograph Study of Oxide Films on Electropolished Surfaces of Iron
159/II
See A b s t r a c t No. : 250/I
26 - -
MATERIALS
--
26
The Use of Silicone Oil as an Operating Fuel for Diffusion Pumps
16o/II
See A b s t r a c t No. : 131/II
Electrically Heated Glass for Airplane Cabins United States. The t y p e of electrically conducting glass considered in this note consists of 2 glass layers
O
separated b y a vinyl plastic which carries a film of stannic oxide, some 20 millionths of 1 inch thick. I n order to avoid cracking of these glass panels w h e n exposed to n o r m a l w e a t h e r conditions, the conductivity of the stannic oxide fihn m u s t be even t h r o u g h o u t the panel. To test the performance of the film the panels are placed in a ' S t r a t o - C h a m b e r ' n o r m a l l y used for high altitude research, and operated in flight conditions encountered in practice. Tile average p o w e r consumed, the power at a control point and the power at the h o t t e s t point of the panel are t h e n determined and as a result the heating p a t t e r n of the panel is established mathematically. The ratio of power at t h e h o t t e s t point to t h a t at the control p o i n t should n o t exceed 1.3 and the t e m p e r a t u r e of the front surface facing the wind should not drop below 40°F, while the h o t t e s t point inside the windshield should n o t exceed 160°F. .%'ommaire : Des p r o b l e m s associ6s avec l'emploi du verre chauff6 61ectriquement dans la construction aerou a u t i q u e s o n t discut~s.
A Vacuum Microbalance for Measuring Sorption in Dielectrics
161/II
b~ote by R. Bloomberg Ceramic Age 59, May 1955 41
162/II
See A b s t r a c t No. : 153/II
z8
-
-
APPARATUS
COMPONENTS
-
-
28
Isolation Valves for Vacuum Systems United K i n g d o m . The chief t y p e s of v a c u u m valve used for isolating one p a r t of a v a c u u m s y s t e m from
163/II
a n o t h e r are classified and m a n y of the designs published in the last t w e n t y years are reviewed. The requiremerits of a v a c u u n l valve are considered and criticisms and c o m m e n t s m a d e regarding existing t y p e s of valve. V a c u u m valves developed f r o m existing valves as used in routine engineering practice as well as valves designed specifically for low p r e s s u r e w o r k are described. An account follows of recent w o r k on valves for ultra high
October, 1953
Vacuum Vol. I I I No. 4
460
II - -
Vacuum
Apparatus
and
Auxiliaries
--
II
Contd.
A Replica Technique in the Study of Chemical Precipitation Processes United States. Vehere precipitates formed b y mixing solutions of chemical reagents are to be studied in tile electron microscope the use of replica techniques is preferable to a direct e x a m i n a t i o n of the specimen. If exposed to the electron b e a m the genuine specimen material tends to decompose or to be c o n t a m i n a t e d b y residual gases in the chamber. F i s c h b e i n developed a 3 - s t e p wet replication process for use w i t h biological specimens. The process described in the p r e s e n t article is a 1-step replication process based on Fischbein's technique. A sandwich is prepared consisting of 2 glass slides holding a drop of the m o t h e r liquid w i t h the precipitate in suspension between them. One of the glass slides is covered w i t h a film of parlodion. A parlodion film of suitable thickness is obtained b y dipping the glass slide into a 3% parlodion solution ill a m y l acetate and s u b s e q u e n t l y drying it. The 2 glass slides are clamped together and the sandwich is heated in the m o t h e r liquid at boiling p o i n t t e m p e r a t u r e for 10 minutes. The sandwich is t h e n t a k e n apart, the precipitate dissolved, the replica floated off the glass slide on w a t e r and picked u p b y screens in the conventional way. I n order to obtain good c o n t r a s t shadowing is essential. The m o s t suitable angle for shadowing was found to be 30 ° . Micrographs of directly viewed specimens and replicas of the same material, e.g. silver clfloride particles, are s h o w n in illustrations. Sommaire : Une nouvelle m6thode de r6plique bas6 sur la in6thode de r6plique h u m i d e de Fischbein des sp6cimens biologiques est d6crite.
Abstract No. and References
157/II
Article by R. B. Fischer & J. P. Ellinger J. AppL Phys. 24, Aug. 1953 1051-1053
O Microstructure of Capacitor Paper
158/1I
See A b s t r a c t No. : 209/I
An Electron-Micrograph Study of Oxide Films on Electropolished Surfaces of Iron
159/II
See A b s t r a c t No. : 250/I
26 - -
MATERIALS
--
26
The Use of Silicone Oil as an Operating Fuel for Diffusion Pumps
16o/II
See A b s t r a c t No. : 131/II
Electrically Heated Glass for Airplane Cabins United States. The t y p e of electrically conducting glass considered in this note consists of 2 glass layers
O
separated b y a vinyl plastic which carries a film of stannic oxide, some 20 millionths of 1 inch thick. I n order to avoid cracking of these glass panels w h e n exposed to n o r m a l w e a t h e r conditions, the conductivity of the stannic oxide fihn m u s t be even t h r o u g h o u t the panel. To test the performance of the film the panels are placed in a ' S t r a t o - C h a m b e r ' n o r m a l l y used for high altitude research, and operated in flight conditions encountered in practice. Tile average p o w e r consumed, the power at a control point and the power at the h o t t e s t point of the panel are t h e n determined and as a result the heating p a t t e r n of the panel is established mathematically. The ratio of power at t h e h o t t e s t point to t h a t at the control p o i n t should n o t exceed 1.3 and the t e m p e r a t u r e of the front surface facing the wind should not drop below 40°F, while the h o t t e s t point inside the windshield should n o t exceed 160°F. .%'ommaire : Des p r o b l e m s associ6s avec l'emploi du verre chauff6 61ectriquement dans la construction aerou a u t i q u e s o n t discut~s.
A Vacuum Microbalance for Measuring Sorption in Dielectrics
161/II
b~ote by R. Bloomberg Ceramic Age 59, May 1955 41
162/II
See A b s t r a c t No. : 153/II
z8
-
-
APPARATUS
COMPONENTS
-
-
28
Isolation Valves for Vacuum Systems United K i n g d o m . The chief t y p e s of v a c u u m valve used for isolating one p a r t of a v a c u u m s y s t e m from
163/II
a n o t h e r are classified and m a n y of the designs published in the last t w e n t y years are reviewed. The requiremerits of a v a c u u n l valve are considered and criticisms and c o m m e n t s m a d e regarding existing t y p e s of valve. V a c u u m valves developed f r o m existing valves as used in routine engineering practice as well as valves designed specifically for low p r e s s u r e w o r k are described. An account follows of recent w o r k on valves for ultra high
October, 1953
Vacuum Vol. I I I No. 4
460