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1746. A reliable automatic refilling device for liquid air or liquid nitrogen cooked traps
Classified abstracts 1742--1757 24 1742. Control valves for cryogenic fluids. (USA) The design of valves to overcome the problems of galling, seizing and stress accumulation caused by very low temperatures is discussed. C S Beard, Control Eng, 13 (3), 1966, 62-72. 24 1743. Vacuum valves. (USA) L D Berringer, Instrum and Control Systems, 38, 1965, 115.
25, Baffles, traps and refrigeration equipment 25:21:22 New Zeiss Jena products in the Spring Leipzig Fair 1966. See abstract number 1709. 25 1744. Fluorinated refrigerant fluids--attainment of low temperatures.
(France) The technology and characteristics as refrigerants are reviewed for CF3C1, CHF3, CBrF3, CHCIF2, C2C1F5, and CF4. M E M Elchardus and M Maestre, Genie Chim, 93 (1), 1965, 6-24
(USSR)
(in French). 25 1745. Vapour trap for arc-spark stands. (USA) A cold-finger trap (dry ice) is described for condensation of vapours. C L Chancy, Appl Spectry, 19 (5), 1965, 165-166. 25 1746. A reliable automatic refilling device for liquid air or liquid nitrogen cooked traps. (Germany) A device is described which can be used either as a fixed-time interval refilling device for several liquid air or liquid nitrogen cooled traps or as a continuously operating liquid level controller. A vapour pressure thermometer with Krypton is used as the liquid level sensing element. The refilling is effected by a control valve applying external pressure or by means of the self-evaporation of the liquid cooling medium. Special attention is paid to the reliability and maintenance-free operation of the device. G Schaal, Vakuum-Technik, 15, ~iay 1966, 111-114 (in German). 25 1747. Porous metal isolation traps and cryosorbents in vacuum technique. (USA) Applications of two general forms of porous metals are discussed: forms pierced through by optically dense pores permitting gas to flow through them and solid core forms with surface porosity only. A m o n g the v a c u u m uses of appropriate porous metals are: isolation trapping of oil during viscous and K n u d s e n gas flow, and cryosorbents. N Milleron, Lawrence Radiation Laboratory, Livermore, University
of California, 1965, 14 pages. 1748. Low-temperature adsorption method for production vacuum. (USSR) Adsorption isotherms obtained for Xe, Kr, Ar, CO adsorbed by activated charcoal at 80°K and 10 -8 -10 4 tort pressure are presented. Isotherms showed that at 10-5 tort pressure lg of activated charcoal adsorbs 100 cm 3 Ke and 100 cm 3 At. Extrapolation of the experimental data to low pressures indicated that this method may be used to obtain a high vacuum down to 10 -11 torr. A N Aliev, Izv Akad Nauk Azerb Ser fiz Tekhn i Mat Nauk, 1965,
80~83 (in Russian). 25 1749. A simple zeolite trap. (USSR) A zeolite trap that permits a v a c u u m of about 1 × 10 -7 tort to be produced in unheated systems without the use of liquid nitrogen is described. (Author) V A Gerasimov, Instrum Exp Tech, Apr 1966, 1280 (Transl from
Pribory i Tekh Eksp, No 5, Sept~Oct 1965). and leak detection
27 1750. Study and development of a new leak detector. (France) In the development of a new leak detector, special emphasis is given to the small size of the detector, various safety devices and automatic operation, its sensitivity of 10- n atm cc sec, and the ease of its maintenance due to the use of easily interchangeable parts. A Richardt, Le Vide, 122, 1966, 146-151 (in French).
512
A new type of mass spectrometer leak detector ( M K h 1102) is described; it has high sensitivity (5 ~ 10-8 l-mtorr/sec) and it has a number of operational advantages over similar instruments of domestic manufacture: linearity of the sensitivity characteristic; calibration by a standard helium leak; protection of the oil-vapour diffusion p u m p from atmospheric air; low background helium; high stability of the sensitivity with respect to time, etc. These merits of the instrument distinguish it favourably from the PTI-6 leak detector. (Authors) V A Pavlenku et al, lnstrum Exp Tech, Apr 1966, 1218 (Translfrom
Pribory i Tekh Eksp, No 5, Sept/Oct 1965).
28. Heating equipment and thermometers 28 1753. A simple temperature control system for use between 4.2°K and room temperature. (Great Britain) Design of a simple and inexpensive control system used to stabilize the temperature of adsorbers in Mossbauer effect experiments to within 0.2°K pver the temperature range 4.2°K to room temperature is described. F W D Woodhams et al, J Sci lnstrum, 43 (5), 1966, 333-334. 28 1754. Measurement of low temperatures by the volt-ampere and recombination characteristics of gallium arsenide diodes. (USSR) V I Osinskii and N N Sirota, Vestsi Akad Navuk Belarusk SSR, Ser
Fiz-Mat Navuk (3), 1965, 130-131 (in Russian). 25 of high
27. L e a k d e t e c t o r s
27 1751. The effect of helium memory on the performance of a mass spectrometer leak detector--and some of the causes. (France) With conventional vacuum techniques as generally used on leak detection mass spectrometers, the reliable detection of leaks smaller than about 10 -11 1 torr/sec, involving the measurement of helium partial pressures of the order of 10-1~ torr and less, can be severely limited by the helium memory of the vacuum system. In most cases, helium is sorbed at high partial pressures by organic materials within the vacuum system, and then desorbed at a much slower rate under low pressure conditions. Under certain conditions back diffusion through the diffusion p u m p can also occur, both from atmospheric helium in the packing line, and from helium adsorbed by the pumping fluids etc. Investigations have been made of all these effects, and as a result recommendations are made for the design of a vacuum system to be used with a high sensitivity mass spectrometer leak detector. Some experimental results of helium background effects are given. S Evans and P Granger, Le Vide, 122, 1966, 132-147. 27 1752. The highly sensitive MKh 1102 mass spectrometer leak detector.
28 1755. The question of temperature control and temperature distributions in furnaces for heat treating purposes. Part 4. Control problems in a laboratory vacuum furnace. (Germany) A series of problems c o m m o n in temperature control and the achievement and control of defined temperature distributions in heat treating furnaces is discussed for a laboratory furnace, which is rebuilt from manual to automatic control. To facilitate the control of temperature and vacuum conditions sensors are used to convert pressure into electrical signals. W Imelmann et al, Harterei Tech Mitt, 20, 1965, 187-192 (in German). 28 1756. Improved temperature control with galvanometer controllers.
(Great Britain) A simple modification of on-off galvanometer controllers by means of a transistorized Gouy modulator enables control to 4-0.1 ° at 600°C and to 4-0.2 ° at 1200°C to be achieved at m i n i m u m cost. Modulated on-off controllers can be used to control furnaces of low thermal capacity. C H L Goodman, J Sci lnstrum, 43 (6), 1966, 393-395. 28 1757. High-temperature glass vacuum cuvette for studying infrared spectra of molecules adsorbed on solids. (USSR) The principal failings of existing glass vacuum cuvettes used in studying the infrared spectra of adsorbed molecules are discussed. These include the presence of lubricant, which interferes with the adsorption measurements, the difficulty of examining spectra at high temperatures, and the siting of the heating element inside the evacuated
25, Baffles, traps and refrigeration equipment 25:21:22 New Zeiss Jena products in the Spring Leipzig Fair 1966. See abstract number 1709. 25 1744. Fluorinated refrigerant fluids--attainment of low temperatures.
(France) The technology and characteristics as refrigerants are reviewed for CF3C1, CHF3, CBrF3, CHCIF2, C2C1F5, and CF4. M E M Elchardus and M Maestre, Genie Chim, 93 (1), 1965, 6-24
(USSR)
(in French). 25 1745. Vapour trap for arc-spark stands. (USA) A cold-finger trap (dry ice) is described for condensation of vapours. C L Chancy, Appl Spectry, 19 (5), 1965, 165-166. 25 1746. A reliable automatic refilling device for liquid air or liquid nitrogen cooked traps. (Germany) A device is described which can be used either as a fixed-time interval refilling device for several liquid air or liquid nitrogen cooled traps or as a continuously operating liquid level controller. A vapour pressure thermometer with Krypton is used as the liquid level sensing element. The refilling is effected by a control valve applying external pressure or by means of the self-evaporation of the liquid cooling medium. Special attention is paid to the reliability and maintenance-free operation of the device. G Schaal, Vakuum-Technik, 15, ~iay 1966, 111-114 (in German). 25 1747. Porous metal isolation traps and cryosorbents in vacuum technique. (USA) Applications of two general forms of porous metals are discussed: forms pierced through by optically dense pores permitting gas to flow through them and solid core forms with surface porosity only. A m o n g the v a c u u m uses of appropriate porous metals are: isolation trapping of oil during viscous and K n u d s e n gas flow, and cryosorbents. N Milleron, Lawrence Radiation Laboratory, Livermore, University
of California, 1965, 14 pages. 1748. Low-temperature adsorption method for production vacuum. (USSR) Adsorption isotherms obtained for Xe, Kr, Ar, CO adsorbed by activated charcoal at 80°K and 10 -8 -10 4 tort pressure are presented. Isotherms showed that at 10-5 tort pressure lg of activated charcoal adsorbs 100 cm 3 Ke and 100 cm 3 At. Extrapolation of the experimental data to low pressures indicated that this method may be used to obtain a high vacuum down to 10 -11 torr. A N Aliev, Izv Akad Nauk Azerb Ser fiz Tekhn i Mat Nauk, 1965,
80~83 (in Russian). 25 1749. A simple zeolite trap. (USSR) A zeolite trap that permits a v a c u u m of about 1 × 10 -7 tort to be produced in unheated systems without the use of liquid nitrogen is described. (Author) V A Gerasimov, Instrum Exp Tech, Apr 1966, 1280 (Transl from
Pribory i Tekh Eksp, No 5, Sept~Oct 1965). and leak detection
27 1750. Study and development of a new leak detector. (France) In the development of a new leak detector, special emphasis is given to the small size of the detector, various safety devices and automatic operation, its sensitivity of 10- n atm cc sec, and the ease of its maintenance due to the use of easily interchangeable parts. A Richardt, Le Vide, 122, 1966, 146-151 (in French).
512
A new type of mass spectrometer leak detector ( M K h 1102) is described; it has high sensitivity (5 ~ 10-8 l-mtorr/sec) and it has a number of operational advantages over similar instruments of domestic manufacture: linearity of the sensitivity characteristic; calibration by a standard helium leak; protection of the oil-vapour diffusion p u m p from atmospheric air; low background helium; high stability of the sensitivity with respect to time, etc. These merits of the instrument distinguish it favourably from the PTI-6 leak detector. (Authors) V A Pavlenku et al, lnstrum Exp Tech, Apr 1966, 1218 (Translfrom
Pribory i Tekh Eksp, No 5, Sept/Oct 1965).
28. Heating equipment and thermometers 28 1753. A simple temperature control system for use between 4.2°K and room temperature. (Great Britain) Design of a simple and inexpensive control system used to stabilize the temperature of adsorbers in Mossbauer effect experiments to within 0.2°K pver the temperature range 4.2°K to room temperature is described. F W D Woodhams et al, J Sci lnstrum, 43 (5), 1966, 333-334. 28 1754. Measurement of low temperatures by the volt-ampere and recombination characteristics of gallium arsenide diodes. (USSR) V I Osinskii and N N Sirota, Vestsi Akad Navuk Belarusk SSR, Ser
Fiz-Mat Navuk (3), 1965, 130-131 (in Russian). 25 of high
27. L e a k d e t e c t o r s
27 1751. The effect of helium memory on the performance of a mass spectrometer leak detector--and some of the causes. (France) With conventional vacuum techniques as generally used on leak detection mass spectrometers, the reliable detection of leaks smaller than about 10 -11 1 torr/sec, involving the measurement of helium partial pressures of the order of 10-1~ torr and less, can be severely limited by the helium memory of the vacuum system. In most cases, helium is sorbed at high partial pressures by organic materials within the vacuum system, and then desorbed at a much slower rate under low pressure conditions. Under certain conditions back diffusion through the diffusion p u m p can also occur, both from atmospheric helium in the packing line, and from helium adsorbed by the pumping fluids etc. Investigations have been made of all these effects, and as a result recommendations are made for the design of a vacuum system to be used with a high sensitivity mass spectrometer leak detector. Some experimental results of helium background effects are given. S Evans and P Granger, Le Vide, 122, 1966, 132-147. 27 1752. The highly sensitive MKh 1102 mass spectrometer leak detector.
28 1755. The question of temperature control and temperature distributions in furnaces for heat treating purposes. Part 4. Control problems in a laboratory vacuum furnace. (Germany) A series of problems c o m m o n in temperature control and the achievement and control of defined temperature distributions in heat treating furnaces is discussed for a laboratory furnace, which is rebuilt from manual to automatic control. To facilitate the control of temperature and vacuum conditions sensors are used to convert pressure into electrical signals. W Imelmann et al, Harterei Tech Mitt, 20, 1965, 187-192 (in German). 28 1756. Improved temperature control with galvanometer controllers.
(Great Britain) A simple modification of on-off galvanometer controllers by means of a transistorized Gouy modulator enables control to 4-0.1 ° at 600°C and to 4-0.2 ° at 1200°C to be achieved at m i n i m u m cost. Modulated on-off controllers can be used to control furnaces of low thermal capacity. C H L Goodman, J Sci lnstrum, 43 (6), 1966, 393-395. 28 1757. High-temperature glass vacuum cuvette for studying infrared spectra of molecules adsorbed on solids. (USSR) The principal failings of existing glass vacuum cuvettes used in studying the infrared spectra of adsorbed molecules are discussed. These include the presence of lubricant, which interferes with the adsorption measurements, the difficulty of examining spectra at high temperatures, and the siting of the heating element inside the evacuated