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362. The use of vacuum in the insulation of vessels and equipment for handling liquefied gases
Classified
abstracts
362-372
20:31 :48 362. The use of vacuum in the insulation of vessels and equipment for handling liquefied gases. (Greut Britain) Description of problems which arise and techniques which have been developed for the high-quality insulation of vessels and equipmenr used in handling the so-called “cryogenic liquids” boiling at or below 90 ‘K. G V Blomfield, In.\r Mech Eng Conf’ Vacuum Technology, London, March 1965. II pages. 20 : 30 : 41 363. Highvacuum apparatus for studying sublimation by the continuous-weighing method. (’USSR) A highvacuum apparatus for studying the sublimation of materials by the continuous-weighing method from room temperature to 600°C is described; it consists of a preliminary pumping system comprising backing and oil-diffusion pumps, a high vacuum slide valve, a working chamber, and a gettering system. The high vacuum valve constitutes a modernized version of a well-known type; its improved characteristics enable the walls of the working chamber to be rapidly degassed. The final rarefactlon reaches 5 x lo-” torr; metal and glass manometers are provided for measuring the residual pressure. (USSR) M B Bronfin and V A Marichev, Zn?otl Labor, (12)) 1965, 1522, (in Russian). 20 : 57 364. Reconstruction of MP-JG machines for making mechanical tests (on metals) in vacua or in a gas medium. (USSR) A revised form of machine for testing the creep and durability of metals in vacua is described. The original form of vacuum chamber associated with this was only suitable for comparatively lowtemperature work; a new vacuum chamber with molybdenum or tungsten heaters was developed, and in addition to providing good vacuum conditions at much higher temperatures this was furnished with windows so as to enable the samples under test to be photographed and the kinetics of crack development traced. The pumping arrangements and electrical control system of the machine are described in full. (USSR) V V Popovich et al, Fiz-khim Mekh Mater, (S) , 1965. 596-597, (in Russian). 20 : 21 365. Relationships between pumping speed, capture probability and chamber geometry in a spherical cryopumped vacuum chamber.(USA) A spherical cryopumped chamber with a test object is analysed to determine the pumping speeds that will be observed with gauges located in various positions Equations are developed to relate these speeds to chamber geometry and cryopump efficiency. It is shown that with a certain geometry and gauge location, speeds as high as four times the orifice speed, V/4, per unit area can be observed with omni-dIrecttonal gauges, and even higher speeds can be obtained with directional gauges. (/ISA) C B Hood and C B Barnes Jr, J Vat Sri Technol, 2 (6), Not*/Dec 1965.302~306. 20 : 21 : 34 366. A large ultrahigh-vacuum environmental chamber with liquid helium cooled walls. (USA) A vacuum chamber is described which can operate with cryowall removed or with both cryowall and inner chamber wall removed. With both these removed, the chamber is capable to pressures of about 2 x IO-@ torr and the test volume is 7.5 ft in diameter and 12 ft long. With only the cryowall removed the pressure can be about 5 z IO *IItorr and the dimensions are 6.5 by 8.5 ft, and the inner chamber wall can dissipate a 10 kW heat load at temperatures below -300°F. When both walls remain. the test volume is 5.5 by The 7 ft and pressures of about 5 ‘i IO I’ torr can be obtained. cryowall can dissipate a 5 kW heat load at less than 300”F, 2 kW at less than 20°K or 1.4 kW at liquid helium temperatures. Design details are given for the vacuum vessel, cryowall, inner chamber wall, bakeout and pumping system, feed-throughs, etc. The system can be returned to atmospheric pressure with dry nitrogen. (Authors) C D Elderkin and J M Bradford, Rep NASA-CR-63623, RCA Service Co, Inc, Camden, NJ, Apri1.1965. 20 : 57 367. Apparatus for testing friction materials in vacuum. (USSR) A newly-developed apparatus for testing the frictional properties of metals and other materials in vacua and in gaseous media is de-
scribed; the system is suitable for a wide range of velocities (I-15 m,%ec) and operating temperatures (150-5OO’C). The coefficient of friction and the sample temperature can be measured continuously, together with the residual pressure in the system and rate of slip. The vacuum in the system is created by an oil-vapour pump with liquid-nitrogen trap. The construction and operation of the apparatus is described in full detail. V L Mamelov et al, ZavodLabor, 31 (12)) 1965, 1528, (in Russian). 20 368. Calculation of multistage low-vacuum systems. (USSR) A method of calculating the geometrical characteristics of various stages in a multistage low-vacuum system is presented. The calculation is made in terms of dimensionless quantities and the results presented in an easily-interpreted form. Specific requirements include the provision of an assigned pumping speed for a limited maximum power, minimum over-all weight, of the pumping system, and maximum reliability in operation; particular solutions for the satisfaction of these requirements are given. The computing method also makes it possible to estimate the possible advantages of adding further stages to the system. V D Dubenets. Irvest Vvssh Ucheb Zaved. Mashinostroenie. -. (10).. 1965,99-100, iin Russian). 20 369. Fabrication of vacuum enclosures. (France) The process is described for the fabrication of vacuum enclosures whereby the enclosure walls are successively machined, cleaned, polished, rinsed, heated under pressure of air, O,, or a suitable gas mixture to produce a superficial oxidation of the wall surfaces. L Peterman, Commissariat of Atomic Energy, France, French Patent I .405,264 (C/B 2ld B246) I Jlrly 1965. Appl12 May 1964.10 pages, (in French).
21. Pumps
and
pump fluids 21
Diffusion-sorption
pumping. See abstract
number
: 16
342.
21 : I8 : 25 An electric discharge as a trap for diffusion pump vacuum systems. See abstract number 351. 21 : 20 Ultrahigh vacuum with extremely high pumping speed. See abstract number 358. 21 :20 Relationships between pumping speed, capture probability and chamber geometry in a spherical cryopumped vacuum chamber. See abstract number 365. 21 : 40 : 47 370. Vapour pressures of vacuum pump oils. (Japan) The vapour pressure date of the following fluids used in vacuum pumps are presented: DC 704, DC 705, Apiezon B, Apiezon C, Lion A, di-2-ethylhexyl phthalate (DEHP), di-2-ethylhexyl sebacate (DEHS), Cellulube 220, Cellulube 300, Convalex 10, and OS 124. Measurements have been made in the pressure range 0.5 to 20 torr with the oil manometer in which the samples themselves are used. I Japan) K Nakayama, J Vat Sot Japan, 8 (IO), Ott 1965, 333-337, (in Japanese). 21 : 34 : 47 371. The influence of the residual gas atmosphere in space chambers on the neutral efflux and critical temperature of tungsten ionizers. (US.41 The changes in work function and the critical temperature for caesium ionization caused by hydrocarbons and oxygen were investigated. The data obtained are compared with results obtained under clean surface conditions in an ultrahigh-vacuum system. The measurements indicate that small amounts of hydrocarbons as well as carbon monoxide and carbon dioxide reduce the work function and increase the critical temperature for surface ionization. It was established that a cryopumped space chamber with one of the liners at 22’K combined with an ion pump, can be equivalent to an ultrahigh-vacuum system. (Author) 0 K Husmann et al, AIAA Paper- 64-693, Hughes Research Labs, Malibu, Calif. 21 372. Theory of a pulsation free piston pump. (Germany) In many instances of industrial practice the pulsating flow in the 151
abstracts
362-372
20:31 :48 362. The use of vacuum in the insulation of vessels and equipment for handling liquefied gases. (Greut Britain) Description of problems which arise and techniques which have been developed for the high-quality insulation of vessels and equipmenr used in handling the so-called “cryogenic liquids” boiling at or below 90 ‘K. G V Blomfield, In.\r Mech Eng Conf’ Vacuum Technology, London, March 1965. II pages. 20 : 30 : 41 363. Highvacuum apparatus for studying sublimation by the continuous-weighing method. (’USSR) A highvacuum apparatus for studying the sublimation of materials by the continuous-weighing method from room temperature to 600°C is described; it consists of a preliminary pumping system comprising backing and oil-diffusion pumps, a high vacuum slide valve, a working chamber, and a gettering system. The high vacuum valve constitutes a modernized version of a well-known type; its improved characteristics enable the walls of the working chamber to be rapidly degassed. The final rarefactlon reaches 5 x lo-” torr; metal and glass manometers are provided for measuring the residual pressure. (USSR) M B Bronfin and V A Marichev, Zn?otl Labor, (12)) 1965, 1522, (in Russian). 20 : 57 364. Reconstruction of MP-JG machines for making mechanical tests (on metals) in vacua or in a gas medium. (USSR) A revised form of machine for testing the creep and durability of metals in vacua is described. The original form of vacuum chamber associated with this was only suitable for comparatively lowtemperature work; a new vacuum chamber with molybdenum or tungsten heaters was developed, and in addition to providing good vacuum conditions at much higher temperatures this was furnished with windows so as to enable the samples under test to be photographed and the kinetics of crack development traced. The pumping arrangements and electrical control system of the machine are described in full. (USSR) V V Popovich et al, Fiz-khim Mekh Mater, (S) , 1965. 596-597, (in Russian). 20 : 21 365. Relationships between pumping speed, capture probability and chamber geometry in a spherical cryopumped vacuum chamber.(USA) A spherical cryopumped chamber with a test object is analysed to determine the pumping speeds that will be observed with gauges located in various positions Equations are developed to relate these speeds to chamber geometry and cryopump efficiency. It is shown that with a certain geometry and gauge location, speeds as high as four times the orifice speed, V/4, per unit area can be observed with omni-dIrecttonal gauges, and even higher speeds can be obtained with directional gauges. (/ISA) C B Hood and C B Barnes Jr, J Vat Sri Technol, 2 (6), Not*/Dec 1965.302~306. 20 : 21 : 34 366. A large ultrahigh-vacuum environmental chamber with liquid helium cooled walls. (USA) A vacuum chamber is described which can operate with cryowall removed or with both cryowall and inner chamber wall removed. With both these removed, the chamber is capable to pressures of about 2 x IO-@ torr and the test volume is 7.5 ft in diameter and 12 ft long. With only the cryowall removed the pressure can be about 5 z IO *IItorr and the dimensions are 6.5 by 8.5 ft, and the inner chamber wall can dissipate a 10 kW heat load at temperatures below -300°F. When both walls remain. the test volume is 5.5 by The 7 ft and pressures of about 5 ‘i IO I’ torr can be obtained. cryowall can dissipate a 5 kW heat load at less than 300”F, 2 kW at less than 20°K or 1.4 kW at liquid helium temperatures. Design details are given for the vacuum vessel, cryowall, inner chamber wall, bakeout and pumping system, feed-throughs, etc. The system can be returned to atmospheric pressure with dry nitrogen. (Authors) C D Elderkin and J M Bradford, Rep NASA-CR-63623, RCA Service Co, Inc, Camden, NJ, Apri1.1965. 20 : 57 367. Apparatus for testing friction materials in vacuum. (USSR) A newly-developed apparatus for testing the frictional properties of metals and other materials in vacua and in gaseous media is de-
scribed; the system is suitable for a wide range of velocities (I-15 m,%ec) and operating temperatures (150-5OO’C). The coefficient of friction and the sample temperature can be measured continuously, together with the residual pressure in the system and rate of slip. The vacuum in the system is created by an oil-vapour pump with liquid-nitrogen trap. The construction and operation of the apparatus is described in full detail. V L Mamelov et al, ZavodLabor, 31 (12)) 1965, 1528, (in Russian). 20 368. Calculation of multistage low-vacuum systems. (USSR) A method of calculating the geometrical characteristics of various stages in a multistage low-vacuum system is presented. The calculation is made in terms of dimensionless quantities and the results presented in an easily-interpreted form. Specific requirements include the provision of an assigned pumping speed for a limited maximum power, minimum over-all weight, of the pumping system, and maximum reliability in operation; particular solutions for the satisfaction of these requirements are given. The computing method also makes it possible to estimate the possible advantages of adding further stages to the system. V D Dubenets. Irvest Vvssh Ucheb Zaved. Mashinostroenie. -. (10).. 1965,99-100, iin Russian). 20 369. Fabrication of vacuum enclosures. (France) The process is described for the fabrication of vacuum enclosures whereby the enclosure walls are successively machined, cleaned, polished, rinsed, heated under pressure of air, O,, or a suitable gas mixture to produce a superficial oxidation of the wall surfaces. L Peterman, Commissariat of Atomic Energy, France, French Patent I .405,264 (C/B 2ld B246) I Jlrly 1965. Appl12 May 1964.10 pages, (in French).
21. Pumps
and
pump fluids 21
Diffusion-sorption
pumping. See abstract
number
: 16
342.
21 : I8 : 25 An electric discharge as a trap for diffusion pump vacuum systems. See abstract number 351. 21 : 20 Ultrahigh vacuum with extremely high pumping speed. See abstract number 358. 21 :20 Relationships between pumping speed, capture probability and chamber geometry in a spherical cryopumped vacuum chamber. See abstract number 365. 21 : 40 : 47 370. Vapour pressures of vacuum pump oils. (Japan) The vapour pressure date of the following fluids used in vacuum pumps are presented: DC 704, DC 705, Apiezon B, Apiezon C, Lion A, di-2-ethylhexyl phthalate (DEHP), di-2-ethylhexyl sebacate (DEHS), Cellulube 220, Cellulube 300, Convalex 10, and OS 124. Measurements have been made in the pressure range 0.5 to 20 torr with the oil manometer in which the samples themselves are used. I Japan) K Nakayama, J Vat Sot Japan, 8 (IO), Ott 1965, 333-337, (in Japanese). 21 : 34 : 47 371. The influence of the residual gas atmosphere in space chambers on the neutral efflux and critical temperature of tungsten ionizers. (US.41 The changes in work function and the critical temperature for caesium ionization caused by hydrocarbons and oxygen were investigated. The data obtained are compared with results obtained under clean surface conditions in an ultrahigh-vacuum system. The measurements indicate that small amounts of hydrocarbons as well as carbon monoxide and carbon dioxide reduce the work function and increase the critical temperature for surface ionization. It was established that a cryopumped space chamber with one of the liners at 22’K combined with an ion pump, can be equivalent to an ultrahigh-vacuum system. (Author) 0 K Husmann et al, AIAA Paper- 64-693, Hughes Research Labs, Malibu, Calif. 21 372. Theory of a pulsation free piston pump. (Germany) In many instances of industrial practice the pulsating flow in the 151