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668. Device for the stabilization of helium cryostat temperatures
Classified Abstracts
328
24.
26.
Valves 24
661. Metering valve for capillary chromatography samples. Great Britain. A capillary column for gas chromatography with a hydrogen flame and ionization current detector was built for estimating low concentrations of hydrocarbons. The gas mixtures to be analysed are obtained from a chemical shock tube and are usually at sub-atmospheric pressure. Difficulty has been encountered in obtaining reproducible results due to variation in the amount of sample introduced. A special valve is described which will transfer a fixed volume of gas at a known sub-atmospheric pressure into the carrier gas, which is introduced into the capillary column at 30 p.s.i.g. W. J. S. D. H. Napier and J. R. Simonson, Oct. 1962, 1831-1832.
661-675
Chem. & Zndustr., (42), 20 24
662. Sliding disc vacuum valves.
Anon., Engineer, 213 (5538), 16 March 1962, 501. 24 663. Device for stabilization of gas flow. Czechoslovakia. This note describes a three-stage device for damping out oscillations of the pressure in a continuous flow apparatus (such as a gas chromatograph). The device consists of three bulbs, each with a capillary leak, inserted in the flow line. Each of the first two bulbs opens into the next, larger, one, so that the system is analogous to a three-stage capacitance/ resistance network. The performance of the device is illustrated by pressure/time records comparing it with simple capillary damping and with simple capacity damping. M. D. A.
Automatic
Protective
and Control Equipment
26 669. Gas detection with the help of semiconductors. United States. Excitation of a semiconductor, such as n-type germanium or silicon, by an electrical impulse or light flash raises the electrical conductivity of the crystal. Removal of the stimulus causes an experimental drop to the original value. Both the original increase and subsequent decrease depend on the nature and motion of the gas in contact with the semiconductor. After previous calibration the records are sufficiently sensitive to detect and measure in a few seconds trace quantities of certain gases at pressures as low as 10 microns. w. 1. s. J. H. Claudet, Chem. & Engng News, 40 (38), 17 Sept. 1962, 62-63. 26 670. Device designed to maintain a constant gas pressure in kinetic systems. Great Britain. A vacuum-tight stainless steel piston pump containing mercury is described which can be attached to a glass high-vacuum line. The movement of the piston is controlled to raise or lower the level of mercury in a glass burette so as to keep the pressure in the system constant. The movement of the piston is recorded upon a chart driven by a synchronous motor to give a record of the volume change with time in the gas phase at constant pressure ; three chart speeds are provided. Pressure control is by matched Pirani gauges in a 50 c/s bridge circuit at low pressures, or by a mercury manometer with sealedin metal contacts at higher pressures. The bridge amplifier is briefly described. (Author, modified) E. R. S. Winter, J. Sci. Znstrum., 38 (9), Sept. 1961, 345-348.
J. Novak and J. Jan&k, J. Sci. Instrum., 38 (9), Sept. 1961, 374. 24 : 32 664. Magnetically operated shutters for use in vacuum systems. Great Britain. Two shutters, which can be operated by an external magnet, are described ; they have proved reliable in high-vacuum systems. One allows selection of any of four apertures, the other is a simple on-off device. (Author) F. S. Feates, .I. Sci. Znsrrum., 38 (12), Dec. 1961, 509. 24 665. Fast closing vacuum valve of large aperture. V, Round, Rev. Sci. Instrum., 33 (7), July 1962, 758-759.
26 671. Vacuum motor. United States. Many operations carried out under vacuum conditions, such as thin film deposition, require the control and movement of components. An electric motor has been specially designed for this purpose. It ccnsists of a solid rotor housed inside a casing which can be clamped to a port in the vacuum chamber. No electrical leads or connections intrude into the chamber. The rotor is actuated by an alternating magnetic field produced by outside coils. Motors of this type ranging from l/20 to 1 h.p. have operated satisfactorily in a vacuum of IO-” torr. w. J. s. Anon., New Scientist, 16 (310), 25 Oct. 1962, 208.
24 666. Bakeable high conductance vacuum valve. D. Mullaney, Rev. Sci. Instrum., 33 (9), Sept. 1962, 1003-1004.
25.
Baffles, Traps and Refrigeration
27.
Equipment 25
667. Solid-state in vacuum systems. Developing a thermoelectric baffle. Canada. The thermoelectric baffle is a new idea in cooling high-vacuum components-so important in new electronic, metallurgical and space techniques. The solid-state device needs almost no maintenance and eliminates compressors. (Author) R. P. Poslawski, Electron. Industr., 21 (5), May 1962, 106109. 25 668. Device for the stabilization of helium cryostat temperatures. Greaf Britain. A simple but sensitive method of detecting small changes in the level of an oil manometer is applied to the stabilization of helium cryostat temperatures. At 3°K a stability to better than 10m4deg K is easily obtained. (Author) C. J. Adkins, J. Sci. Znstrum., 38 (7), July 1961, 305.
Leak Detectors and Leak Detection
27 672. High vacuum pump. Announcement by Varian Associates of a 15 l./sec pump of the electronic type, suitable for the range 1O-2-1O-10torr. Anon., Electronic Equipm. News, 4, Aug. 1962, 15. 27 673. Leak tests on Calder-type reactors. J. K. Smith and J. Cheetham, J. Brit. Nucl. Energy Conf., 6 (l), Jan. 1961, 62-69. 27 674. Residual gas analyser. Announcement, by Consolidated Electrodynamics Corp., Pasadena, California, of an instrument for the continuous analysis of residual gases in vacuum systems. The mass range is 2-80, and the gas partial pressures may be in the range 10-*-10-10 torr. Anon., J. Sci. Instrum., 38 (7), July 1961, 311. 27 675. Diode leak-detector unit. Great Britain. This note describes a control unit for a thoriatedtungsten-filament diode, which can be used as a leak detector ;
328
24.
26.
Valves 24
661. Metering valve for capillary chromatography samples. Great Britain. A capillary column for gas chromatography with a hydrogen flame and ionization current detector was built for estimating low concentrations of hydrocarbons. The gas mixtures to be analysed are obtained from a chemical shock tube and are usually at sub-atmospheric pressure. Difficulty has been encountered in obtaining reproducible results due to variation in the amount of sample introduced. A special valve is described which will transfer a fixed volume of gas at a known sub-atmospheric pressure into the carrier gas, which is introduced into the capillary column at 30 p.s.i.g. W. J. S. D. H. Napier and J. R. Simonson, Oct. 1962, 1831-1832.
661-675
Chem. & Zndustr., (42), 20 24
662. Sliding disc vacuum valves.
Anon., Engineer, 213 (5538), 16 March 1962, 501. 24 663. Device for stabilization of gas flow. Czechoslovakia. This note describes a three-stage device for damping out oscillations of the pressure in a continuous flow apparatus (such as a gas chromatograph). The device consists of three bulbs, each with a capillary leak, inserted in the flow line. Each of the first two bulbs opens into the next, larger, one, so that the system is analogous to a three-stage capacitance/ resistance network. The performance of the device is illustrated by pressure/time records comparing it with simple capillary damping and with simple capacity damping. M. D. A.
Automatic
Protective
and Control Equipment
26 669. Gas detection with the help of semiconductors. United States. Excitation of a semiconductor, such as n-type germanium or silicon, by an electrical impulse or light flash raises the electrical conductivity of the crystal. Removal of the stimulus causes an experimental drop to the original value. Both the original increase and subsequent decrease depend on the nature and motion of the gas in contact with the semiconductor. After previous calibration the records are sufficiently sensitive to detect and measure in a few seconds trace quantities of certain gases at pressures as low as 10 microns. w. 1. s. J. H. Claudet, Chem. & Engng News, 40 (38), 17 Sept. 1962, 62-63. 26 670. Device designed to maintain a constant gas pressure in kinetic systems. Great Britain. A vacuum-tight stainless steel piston pump containing mercury is described which can be attached to a glass high-vacuum line. The movement of the piston is controlled to raise or lower the level of mercury in a glass burette so as to keep the pressure in the system constant. The movement of the piston is recorded upon a chart driven by a synchronous motor to give a record of the volume change with time in the gas phase at constant pressure ; three chart speeds are provided. Pressure control is by matched Pirani gauges in a 50 c/s bridge circuit at low pressures, or by a mercury manometer with sealedin metal contacts at higher pressures. The bridge amplifier is briefly described. (Author, modified) E. R. S. Winter, J. Sci. Znstrum., 38 (9), Sept. 1961, 345-348.
J. Novak and J. Jan&k, J. Sci. Instrum., 38 (9), Sept. 1961, 374. 24 : 32 664. Magnetically operated shutters for use in vacuum systems. Great Britain. Two shutters, which can be operated by an external magnet, are described ; they have proved reliable in high-vacuum systems. One allows selection of any of four apertures, the other is a simple on-off device. (Author) F. S. Feates, .I. Sci. Znsrrum., 38 (12), Dec. 1961, 509. 24 665. Fast closing vacuum valve of large aperture. V, Round, Rev. Sci. Instrum., 33 (7), July 1962, 758-759.
26 671. Vacuum motor. United States. Many operations carried out under vacuum conditions, such as thin film deposition, require the control and movement of components. An electric motor has been specially designed for this purpose. It ccnsists of a solid rotor housed inside a casing which can be clamped to a port in the vacuum chamber. No electrical leads or connections intrude into the chamber. The rotor is actuated by an alternating magnetic field produced by outside coils. Motors of this type ranging from l/20 to 1 h.p. have operated satisfactorily in a vacuum of IO-” torr. w. J. s. Anon., New Scientist, 16 (310), 25 Oct. 1962, 208.
24 666. Bakeable high conductance vacuum valve. D. Mullaney, Rev. Sci. Instrum., 33 (9), Sept. 1962, 1003-1004.
25.
Baffles, Traps and Refrigeration
27.
Equipment 25
667. Solid-state in vacuum systems. Developing a thermoelectric baffle. Canada. The thermoelectric baffle is a new idea in cooling high-vacuum components-so important in new electronic, metallurgical and space techniques. The solid-state device needs almost no maintenance and eliminates compressors. (Author) R. P. Poslawski, Electron. Industr., 21 (5), May 1962, 106109. 25 668. Device for the stabilization of helium cryostat temperatures. Greaf Britain. A simple but sensitive method of detecting small changes in the level of an oil manometer is applied to the stabilization of helium cryostat temperatures. At 3°K a stability to better than 10m4deg K is easily obtained. (Author) C. J. Adkins, J. Sci. Znstrum., 38 (7), July 1961, 305.
Leak Detectors and Leak Detection
27 672. High vacuum pump. Announcement by Varian Associates of a 15 l./sec pump of the electronic type, suitable for the range 1O-2-1O-10torr. Anon., Electronic Equipm. News, 4, Aug. 1962, 15. 27 673. Leak tests on Calder-type reactors. J. K. Smith and J. Cheetham, J. Brit. Nucl. Energy Conf., 6 (l), Jan. 1961, 62-69. 27 674. Residual gas analyser. Announcement, by Consolidated Electrodynamics Corp., Pasadena, California, of an instrument for the continuous analysis of residual gases in vacuum systems. The mass range is 2-80, and the gas partial pressures may be in the range 10-*-10-10 torr. Anon., J. Sci. Instrum., 38 (7), July 1961, 311. 27 675. Diode leak-detector unit. Great Britain. This note describes a control unit for a thoriatedtungsten-filament diode, which can be used as a leak detector ;