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670. A multistage vacuum pump
Classified
abstracts
670-679 ‘1
670. A multistage vacuum pump. (USSR) An improved form of multistage vacuum pump is described. Whereas many existing multistage vacuum pumps with a vapour-jet ejector in each stage have the condensers of the individual stages established all at one level, in the proposed pump the condensers of contiguous stages are established at different levels and joined by a hydraulic valve. This makes it possible to economize in the cooling water by using it successively in several stages. S I Vil’der, USSR Patent 189,509, Appl9th Ott 1965, Pub1 10th Jan 1967. 22. GAUGES
22 671. Investigation of the application of a vacuum microbalance to the measurement absolute pressure in high vacuum. (Germany) The possibility of employing a vacuum microbalance as a Knudsen gauge was investigated. Sources of error and their bearing upon absolute pressure determinations are discussed. Absolute pressure is measured as a function of the torsion developed between two differentially heated plates which are separated by a short distance. Preliminary results indicate that pressures down to the 10-j torr range may be determined with accuracy of a few per cent. This gauge has the advantage of direct pressure measurement and freedom from zero drift and alterations in sensitivity. The interchangeable heated plates make the gauge useful for determination of accommodation coefficients. H L Eschbach and H Moret, Vakuum-Technik, 17 (2), Feb 1968, 29-33 (in German). 22 672. Pressure measurements based on “longitudinal” Knudsen forces.
(Germany) Longitudinal Knudsen forces were recently introduced to explain a fundamental error in microbalances at high and low temperature operation. These forces originate from temperature gradients and act in directions parallel to the sample surface. At low pressures these forces are proportional to gas pressure and independent of the nature of the gas. The possibility of using these forces as a basis for pressure measurement was investigated by means of a microbalance having a sensitivity of 5 x 10m4 dyne. Preliminary results gave a pressure sensitivity of about 20 per cent in the range 1O-6to lO-2 torr. C H Massen et al, Vakuum-Technik, 17 (2), Feb 1968, 34-36 (in German). 22 673. Capillary depression in McLeod gauges.
(Great Britain) A source of the irreproducibility in measuring low pressure with a McLeod gauge is described. Particular attention has been paid to the capillary phenomena in narrow tubes. The form of a meridional section of a mercury meniscus in cylindrical tube has been calculated with a high-speed digital computer from the Laplace differential equation which has an entirely theoretical basis. Experimental data for capillary tubes differing in material, bore, and condition of inner surface have been compared with the computed values. It is observed that the capillary depression extensively varies, depending presumably on the surface condition of glass. Cancellation of the capillary depression, therefore, can be hardly expected even in the conventional McLeod gauges having twin capillaries. Tapping is found to be effective in reducing the irregular variation of the capillary depression. K Nakayama et al, Vacuum, 18 (2), Feb 1968, 65-71. 22 674. A comparative study of modulated Bayard-Alpert gauges and an extractor gauge. (Great Britain) The experimental results obtained from two different modulated Bayard-Alpert gauges and one extractor gauge are described. The ion-current pressure characteristics show that the two modulator gauges have a most probable error of &I50 per cent at a pressure of approximately 5 x lo- l1 torr. The extractor gauge showed a slow departure from linearity below 5 x lo-l0 torr, but the lower limit of pressure measurement could not be established as the system ultimate pressure was only 1 x 10-l’ torr. The upper working pressure limits vary between 2 x 10-O and I x lO-3 torr depending on the gauge. The sensitivity of the extractor gauge increased very considerably when the electron emission current rose above 10m3A. A similar effect was observed, but to a much smaller extent, on the modulator gauges. The reverse x-ray current effect was shown to account for the premature fall off in linearity at low pressures of one of the modulated gauges
when its bulb potential was the same as that of the ion collector. J S Cleaver and W H Zakrzewski, Vacuum, 18 (2), Feb 1968, 73-78. 22 675. Study of low pressure application of the Orbitron. (USA) Orbitron vacuum gauge performance is reported with emphasis on low pressure response characteristics. A linear ion current to pressure response was found for the range lo-* to IO-‘” torr. A sensitivity of 0.02 A/torr (dry air equivalent) was measured for a 1.0 micro-amp emission. High sensitivity in relation to emission current results from the long orbiting path length which ionizing electrons travel. Still higher sensitivities and lower residual pressure equivalents can be obtained by employing longer path length. The moderate operation reported here gave very stable response. Residual readings were dependent upon gauge outgassing history indicating a contribution from electronic d&or&on as well as x-ray photocurient. P J Bryant and C M Gosselin, Rep NASA-CR-886, Sept 1967, 24 pages (Sci Tech Aerospace
Reps, 5 (21), 3847, N67-35672).
22 676. A portable calibrator for intermediate range vacuum gauges.
(USA) A portable calibrator to facilitate “in-place” calibration of intermediate range pressure transducers has been developed. The operating principle of the calibrator is to transfer gas, in controllable mass increments, into an initially evacuated vessel of known volume by use of a transfer volume. By adjusting the mass increments to specific predetermined levels, the pressure in the initially evacuated vessel can be increased in steps of 0.001, 0.01, 0.1 or 1 torr. the pressure ranges covered being from 0.001 to 1 torr, and from 1 to 30 torr. The indicated corresponding limits of error applicable to each range are plus or minus 1.3 and plus or minus 0.76 per cent of desired pressure level, respectively. G D Arney and W R Henderson, Rep AEDC-TR-67-83; A D-654279, May 1967, llpages
(Sci Tech Aerospace
Reps, 5 (21), 851, N67-36167).
^_ LL
677. On the pumping effect of type MM-14 inverted magnetron gauges. (USSR) A thoroughly baked system was pumped by the MM-14 inverted magnetron gauge head and from the pressure changes the pumping effect of the gauge was determined. The degassing of the system and of the gauge head was not taken into account. Pumping speeds of 0.24 to 0.3 litres/sec at 10d8 torr and of 0.3 to 0.38 litres/sec at 10mla torr were determined and the lower values were obtained for gauge heads with lower sensitivity. The conductance of the nude gauge head (MM-14) was I8 litresisec, of the metal tubulated gauge head (MM-IIM) was 4 litreslsec and of the glass tubulated gauge head (MM-14s) was 2 litreslsec. V T Grinchenko and G A Nichiporovich, Pribory Tekh Eksper, 12 (6). Nov-Dee 1967. 125-127 (in Russian). 22 678. Compression manometer of the McLeod type.
(USSR) A new compression manometer of the McLeod type is described; this contains a compression cylinder with measuring and comparison capillaries, and is distinguished from analogous existing instruments by the fact that, in order to simplify the construction and facilitate measurements by the repeated-compression method, a constriction is placed between the compression cylinder and the measuring capillary, the diam:ter of this constriction being such as to retard the outflow of the manometric liquid for a tim: sufficient to allow the next portion of gas under test to be taken in. A I lvanov. USSR Patent 190.629. Anpl25th Feb 1965. Pub1 10th Feb ._ 1967. ’ 23. PLUMBING
23 : 33 Heat-resistant (bakeable) constructions for high-vacuum electrophysical apparatus. See abstract number 734. 23 : 27 679. Zero leakage effort for Saturn vehicles. (USA) In application to launchings of missiles, rockets, and space vehicles. statistical data are presented on monitoring zero-leakage test prcgrammes for Saturn I, IB, and V. A compilation of all seals and connections in the vehicle systems for monitoring the zero-leakage programme is presented and include measuring leakage on flange 297
abstracts
670-679 ‘1
670. A multistage vacuum pump. (USSR) An improved form of multistage vacuum pump is described. Whereas many existing multistage vacuum pumps with a vapour-jet ejector in each stage have the condensers of the individual stages established all at one level, in the proposed pump the condensers of contiguous stages are established at different levels and joined by a hydraulic valve. This makes it possible to economize in the cooling water by using it successively in several stages. S I Vil’der, USSR Patent 189,509, Appl9th Ott 1965, Pub1 10th Jan 1967. 22. GAUGES
22 671. Investigation of the application of a vacuum microbalance to the measurement absolute pressure in high vacuum. (Germany) The possibility of employing a vacuum microbalance as a Knudsen gauge was investigated. Sources of error and their bearing upon absolute pressure determinations are discussed. Absolute pressure is measured as a function of the torsion developed between two differentially heated plates which are separated by a short distance. Preliminary results indicate that pressures down to the 10-j torr range may be determined with accuracy of a few per cent. This gauge has the advantage of direct pressure measurement and freedom from zero drift and alterations in sensitivity. The interchangeable heated plates make the gauge useful for determination of accommodation coefficients. H L Eschbach and H Moret, Vakuum-Technik, 17 (2), Feb 1968, 29-33 (in German). 22 672. Pressure measurements based on “longitudinal” Knudsen forces.
(Germany) Longitudinal Knudsen forces were recently introduced to explain a fundamental error in microbalances at high and low temperature operation. These forces originate from temperature gradients and act in directions parallel to the sample surface. At low pressures these forces are proportional to gas pressure and independent of the nature of the gas. The possibility of using these forces as a basis for pressure measurement was investigated by means of a microbalance having a sensitivity of 5 x 10m4 dyne. Preliminary results gave a pressure sensitivity of about 20 per cent in the range 1O-6to lO-2 torr. C H Massen et al, Vakuum-Technik, 17 (2), Feb 1968, 34-36 (in German). 22 673. Capillary depression in McLeod gauges.
(Great Britain) A source of the irreproducibility in measuring low pressure with a McLeod gauge is described. Particular attention has been paid to the capillary phenomena in narrow tubes. The form of a meridional section of a mercury meniscus in cylindrical tube has been calculated with a high-speed digital computer from the Laplace differential equation which has an entirely theoretical basis. Experimental data for capillary tubes differing in material, bore, and condition of inner surface have been compared with the computed values. It is observed that the capillary depression extensively varies, depending presumably on the surface condition of glass. Cancellation of the capillary depression, therefore, can be hardly expected even in the conventional McLeod gauges having twin capillaries. Tapping is found to be effective in reducing the irregular variation of the capillary depression. K Nakayama et al, Vacuum, 18 (2), Feb 1968, 65-71. 22 674. A comparative study of modulated Bayard-Alpert gauges and an extractor gauge. (Great Britain) The experimental results obtained from two different modulated Bayard-Alpert gauges and one extractor gauge are described. The ion-current pressure characteristics show that the two modulator gauges have a most probable error of &I50 per cent at a pressure of approximately 5 x lo- l1 torr. The extractor gauge showed a slow departure from linearity below 5 x lo-l0 torr, but the lower limit of pressure measurement could not be established as the system ultimate pressure was only 1 x 10-l’ torr. The upper working pressure limits vary between 2 x 10-O and I x lO-3 torr depending on the gauge. The sensitivity of the extractor gauge increased very considerably when the electron emission current rose above 10m3A. A similar effect was observed, but to a much smaller extent, on the modulator gauges. The reverse x-ray current effect was shown to account for the premature fall off in linearity at low pressures of one of the modulated gauges
when its bulb potential was the same as that of the ion collector. J S Cleaver and W H Zakrzewski, Vacuum, 18 (2), Feb 1968, 73-78. 22 675. Study of low pressure application of the Orbitron. (USA) Orbitron vacuum gauge performance is reported with emphasis on low pressure response characteristics. A linear ion current to pressure response was found for the range lo-* to IO-‘” torr. A sensitivity of 0.02 A/torr (dry air equivalent) was measured for a 1.0 micro-amp emission. High sensitivity in relation to emission current results from the long orbiting path length which ionizing electrons travel. Still higher sensitivities and lower residual pressure equivalents can be obtained by employing longer path length. The moderate operation reported here gave very stable response. Residual readings were dependent upon gauge outgassing history indicating a contribution from electronic d&or&on as well as x-ray photocurient. P J Bryant and C M Gosselin, Rep NASA-CR-886, Sept 1967, 24 pages (Sci Tech Aerospace
Reps, 5 (21), 3847, N67-35672).
22 676. A portable calibrator for intermediate range vacuum gauges.
(USA) A portable calibrator to facilitate “in-place” calibration of intermediate range pressure transducers has been developed. The operating principle of the calibrator is to transfer gas, in controllable mass increments, into an initially evacuated vessel of known volume by use of a transfer volume. By adjusting the mass increments to specific predetermined levels, the pressure in the initially evacuated vessel can be increased in steps of 0.001, 0.01, 0.1 or 1 torr. the pressure ranges covered being from 0.001 to 1 torr, and from 1 to 30 torr. The indicated corresponding limits of error applicable to each range are plus or minus 1.3 and plus or minus 0.76 per cent of desired pressure level, respectively. G D Arney and W R Henderson, Rep AEDC-TR-67-83; A D-654279, May 1967, llpages
(Sci Tech Aerospace
Reps, 5 (21), 851, N67-36167).
^_ LL
677. On the pumping effect of type MM-14 inverted magnetron gauges. (USSR) A thoroughly baked system was pumped by the MM-14 inverted magnetron gauge head and from the pressure changes the pumping effect of the gauge was determined. The degassing of the system and of the gauge head was not taken into account. Pumping speeds of 0.24 to 0.3 litres/sec at 10d8 torr and of 0.3 to 0.38 litres/sec at 10mla torr were determined and the lower values were obtained for gauge heads with lower sensitivity. The conductance of the nude gauge head (MM-14) was I8 litresisec, of the metal tubulated gauge head (MM-IIM) was 4 litreslsec and of the glass tubulated gauge head (MM-14s) was 2 litreslsec. V T Grinchenko and G A Nichiporovich, Pribory Tekh Eksper, 12 (6). Nov-Dee 1967. 125-127 (in Russian). 22 678. Compression manometer of the McLeod type.
(USSR) A new compression manometer of the McLeod type is described; this contains a compression cylinder with measuring and comparison capillaries, and is distinguished from analogous existing instruments by the fact that, in order to simplify the construction and facilitate measurements by the repeated-compression method, a constriction is placed between the compression cylinder and the measuring capillary, the diam:ter of this constriction being such as to retard the outflow of the manometric liquid for a tim: sufficient to allow the next portion of gas under test to be taken in. A I lvanov. USSR Patent 190.629. Anpl25th Feb 1965. Pub1 10th Feb ._ 1967. ’ 23. PLUMBING
23 : 33 Heat-resistant (bakeable) constructions for high-vacuum electrophysical apparatus. See abstract number 734. 23 : 27 679. Zero leakage effort for Saturn vehicles. (USA) In application to launchings of missiles, rockets, and space vehicles. statistical data are presented on monitoring zero-leakage test prcgrammes for Saturn I, IB, and V. A compilation of all seals and connections in the vehicle systems for monitoring the zero-leakage programme is presented and include measuring leakage on flange 297