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Automatic liquid nitrogen refiler
Vacuum
news
Brew tungsten mesh Richard D Brew and Co, USA, have announced the availability of tungsten wire mesh from their refractory metala production facility. Originally developed to provide heating elements in their high temperature vacuum furnaces. the tungsten mesh has proved its ability to withstand temperatures up to 3000 C while retaining mechanical strength. A 20-page brochure is available containing I6 pages of specification data covering single- and 3-phase elements, dimensions, type of weave and resistance values with tolerances of ! 5 per cent. A price list is also included.
R D Brew & Co. USA Cit~k WI/F//W).50 017 Rcurkr
Ettytriry
Service
(.NIYI
Motor for use in high vacuum Dividean Inc. Maryland, USA, have introduced the Vid.E.Motor, considered to be a new approach to high vacuum tooling and claimed to eliminate entirely problems of contamination from motor windings and lubricants. The design concept is that of an electric motor encapsulated in a vacuum tight housing. Motion is transmitted by means of a magnetic coupling and, to allow maximum flexibility in selection of motor types, one housing is made universal for all Vid.E.Motor power modules: ovel 1000 power modules arc easily interchangeable using only ordinary tools. Construction is in 2024-T4 aluminium. with stainless steel shaft and bearing, using a special lubricant, and static Viton seals. The motor operates, either entirely within the vacuum chamber or through the chamber wall. It is bakeable to I25 C and usable at pressures down to IO ’ torr. Speeds from 0.03 to 3000 rpm are possible under torques up to 12 inch/ounce. Recommended applications include mask and substrate manipulation, shutter actuation, in-situ crystal cleavage, electron beam target manipulation, beam chopping and materials transport.
Dividean Inc, USA C‘;t& /77777//~ 5 I 077 Rwth
O7yr/iry Scrviw
ctrrtl
gun systems but may now be supplied to match customer specified cables and connections. An unusual feature of this model is that the 20 kV dual high voltage lines are led into the vacuum th;ough &ly a oneinch hole. The unit is rated at 24 kV. between high voltage and ground (base: plate), and 30 amps. The dual feedthroughs may carry filament power between the two lines at the same time as supplying high voltage. Use of a special ceramic avoids breakage problems which frequently occur with comparable high voltage feedthroughs. A transformer/power supply, I I-1 5 20KV. recommended for electron beam ~LIII operation, is also available.
Veeco Instruments Inc, USA Circle curd
Vicl. E.Mofor
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high
IYICIIIIII~ opc~ration
High voltage high vacuum feedthrough Veeco Instruments Inc, USA, have announced the availability of their DFT high voltage, high vacuum feedthrough as a separate item. The feedthrough is usually incorporated in model VeB6 electron beam 662
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52 on Rcurkw
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knife-edge bearing at the top of the frame and linked to the moving contact htcms of lhc switches, and to the tight auxiliary contacts mounted on the front of the frame. Universal joints locate the VKLILII~ hwitchch in position so that the contacts move linearly despite the slight rotary movement of the armature. Careful design ensures that the relative movements of the vacuum switches, magnetic cores and auxiliary COW tacts are provided by the single lever armature. A dc magnetic system is used to reduce noise and wear. Power interruptions are almost inaudible, the only significant sound being the opening and closing of the armature. For three phase direct-on motel starting duties the vacuum switches are designed to complete at least two million operations on full load before replacement, and the contactors will complete at least ten million mechanical operations. In contrast, it is usual to check and maintain conventional oil or air-break contactors every 100.000 operations and rcolacement of the main contacts is often’ required uftel 250,000 operations. Performance has been tested satisfactorily at operating rates LIP to 7200 an hour. A major feature of the vacuum contaclor is the absence of current chopping-the vacuum switch breaks the circuit when the first zero in the current waveform is reached, so high voltage transients are not created. This facilitv is important in modern electronically-&ntrolled industrial plants. The elimination of arc chutes enables the size of the new vacuum contactors to be reduced to two-fifths of the volume of an equivalent air-break contactor. Each unit measures 8: inches high by 91 wide and 9.1 deep and weighs 25 lb. This compact size is advantage& in the design of flameproof enclosures. The Cact that- the arcs ‘are contined within the vacuum switch envelopes is an advantage for hazardous areas. An important pal-t of the development programme has been the assignment of ratings in accordance with the International Electrotechnical C‘ommission IECl58 Part I and VDE0660 soecifications. as well as BS775 : 1956.
AEI, Control ‘Equipment Division, UK Circlr trvttrhrr 53 ott Rccttkr Ettqrriry~ .Sc,t,viw (Wtl
Advanced vacuum contactors
Automatic liquid nitrogen refiller
Since the introduction of vacuum contactors in 1965, AEI have opened successful application fields throughout the process industries and in steel works, mines, cement plants, quarries and other exacting environments. AEI Control Equipment have recently announced the development of new types of vacuum contactors: rated at 220 A, 660 V for medium-size motor starting duty (up to I75 hp at 440 V); and I50 A. II00 V for mining applications. This is the first time that the advantages of vacuum contactor control devices (reliability, minimum maintenance and compactness) have been extended to these widespread and important uses. Each unit has a durable and rigid polyester resin-bonded, glass-filled moulded plastic frame carrying three AEI vacuum switches. An armature operated by two magnet coils is hinged on a
Leybold-Heraeus have developed an automatic refiller, working either mechanically or electrically, for maintaining the level of the liquid in a dewar vessel, cryostat or cold trap. This device extends the working periods of vacuum systems, particularly mercury diffusion pumped systems. A tenlitre storage tank for liquid nitrogen is also available for the refiller. Ten litres of nitrogen will allow unattended operation ol the Quick 100 pump (mercury diffusion) for 40 hours, the Quick 500 for 20 hours and the Quick 2000 for IO hours. The cold traps of the 100 and 500 Quick pumps may have either mechanical or electrical rcfilling but those of the 2000 and 8000 pumps can only be electrically refilled. In the mechanical unit, operation is by a methane-filled bellows and sensing probe which dips into the trap. While the probe
Vacuum news
good corrosion resistance. Nickel is superior to stainless steel in solderability and weldability and should find many applications in research laboratories. Specifications and prices are the same as for stainless steel Flexpand. The company is also offering ceramic insulator blocks (2 x 2 x 1 inch) in high grade steatite. Female threads are situated at each end of the blocks facilitating mounting and connections. These insulator blocks are unusually low-priced and may be used in the construction of substrate heaters, electron beam guns, thin film sources, nude Bayard-Alpert gauges etc. Mason-Renshaw, USA Circle number 56 on Reader Enquiry Service card Automatic liquid nitrogen refilfer
is submerged, methane is condensed in the bellows and an air vent valve is kept open. When the coolant level drops to uncover the probe, the rise in temperature evaporates some methane, expanding the bellows to close the air-vent valve. Excess pressure then forces the liquid nitrogen through a vacuum-jacketed feed tube into the trap. In the electrical unit, a semiconductor diode replaces the mechanical probe and temperature change causes a change in resistance. The diode is part of a bridge circuit controlling a magnetic valve which effects the refilling in a manner similar to the mechanical unit. For both systems, an adaptor is available which takes the excess nitrogen on overfilling, thus keeping coolant losses down to a minimum. Leyhold-Heraeus Ltd, UK Circle number 54 on Reader Enquiry Service card 2000 Gallon liquid helium dewar
Gardner Cryogenics Corp, USA, have introduced a 2000 gallon liquid helium dewar designed for over-the-road shipment of bulk quantities of liquid helium. The dewar is constructed of a stainless steel inner helium vessel which is thermally insulated from the carbon steel outer shell by a combination of high vacuum and liquid nitrogen. The inner vessel is specially shock mounted to protect it from the stresses and strains normally encountered during handling and hauling. The dewar is 18 ft 10 inches long, has a diameter of 6 ft 8 inches and a height of 6 ft 10 inches. The dewar weighs 8700 pounds empty and when fully loaded weighs 11,015 pounds. Maximum allowable working pressure for helium is 40 psig and for LN2, 10 psig. Boil off rate is 1 per cent per day. Gardner Cryogenics Corporation, USA Circle number 55 on Reader Enquiry Service card
Flexible nickel tubing Mason-Renshaw of California, USA, have announced the availability of their Flexpand metal tubing in pure nickel. The tubing was previously only available in type 321 stainless steel. The nickel tubing is easily degassed, spot-welded or joined to other parts by hard or soft solder, and has
Pumping of food products The transfer of difficult-to-handle liquids and semi-solids such as fruit pulps, soups and delicate liquids, which may be damaged by conventional pumping,is effectively Gardner’s 2000 gallon liquid helium dewar
performed indirectly using a Megator air displacement unit so that the products do not pass through the pump. A standard Megator sliding-shoe pump operates as an oil-free exhauster/compressor unit connected to a pressure/vacuum vessel with appropriate valving. During the suction cycle, air is drawn from the product vessel and discharged to exhaust, filling the vessel with the product. During discharge, air is drawn through a suction filter and compressed in the vessel to displace the product. A high level cut-out to stop the exhauster/ compressor unit automatically when the vessel is full is available as an ontional extra. The Megator air displacement units provide a simple, effective solution to this transfer problem and are available in a range of capacities to suit many applications. Megator Pumps and Compressors Ltd, UK Circle number 57 on Reader Enquiry Service card
Solution of an internal glazing problem The problem of passing a 10 ft 8 inch x 12 ft sheet of b inch plate glass (weighing 640 lb) through a shallow window opening, in a new office block in South East London. was solved by using a lorry-mounted crane fitted with vacuum equipment. Aygee (Glass) Ltd.. glazing contractors for the building,. were-able io tilt the glass at an angle which allowed it to pass between the transomes of the window opening. The glass sheet was required as an internal screen and once inside the building the beam was turned through 90 degrees to bring the plate into correct alignment for fixing. Aygee (Glass) Ltd, UK Circle number 58 on Reader Enquiry Service card
Solution of Aygee’s glazing problem by means of a suction device
news
Brew tungsten mesh Richard D Brew and Co, USA, have announced the availability of tungsten wire mesh from their refractory metala production facility. Originally developed to provide heating elements in their high temperature vacuum furnaces. the tungsten mesh has proved its ability to withstand temperatures up to 3000 C while retaining mechanical strength. A 20-page brochure is available containing I6 pages of specification data covering single- and 3-phase elements, dimensions, type of weave and resistance values with tolerances of ! 5 per cent. A price list is also included.
R D Brew & Co. USA Cit~k WI/F//W).50 017 Rcurkr
Ettytriry
Service
(.NIYI
Motor for use in high vacuum Dividean Inc. Maryland, USA, have introduced the Vid.E.Motor, considered to be a new approach to high vacuum tooling and claimed to eliminate entirely problems of contamination from motor windings and lubricants. The design concept is that of an electric motor encapsulated in a vacuum tight housing. Motion is transmitted by means of a magnetic coupling and, to allow maximum flexibility in selection of motor types, one housing is made universal for all Vid.E.Motor power modules: ovel 1000 power modules arc easily interchangeable using only ordinary tools. Construction is in 2024-T4 aluminium. with stainless steel shaft and bearing, using a special lubricant, and static Viton seals. The motor operates, either entirely within the vacuum chamber or through the chamber wall. It is bakeable to I25 C and usable at pressures down to IO ’ torr. Speeds from 0.03 to 3000 rpm are possible under torques up to 12 inch/ounce. Recommended applications include mask and substrate manipulation, shutter actuation, in-situ crystal cleavage, electron beam target manipulation, beam chopping and materials transport.
Dividean Inc, USA C‘;t& /77777//~ 5 I 077 Rwth
O7yr/iry Scrviw
ctrrtl
gun systems but may now be supplied to match customer specified cables and connections. An unusual feature of this model is that the 20 kV dual high voltage lines are led into the vacuum th;ough &ly a oneinch hole. The unit is rated at 24 kV. between high voltage and ground (base: plate), and 30 amps. The dual feedthroughs may carry filament power between the two lines at the same time as supplying high voltage. Use of a special ceramic avoids breakage problems which frequently occur with comparable high voltage feedthroughs. A transformer/power supply, I I-1 5 20KV. recommended for electron beam ~LIII operation, is also available.
Veeco Instruments Inc, USA Circle curd
Vicl. E.Mofor
fbr
high
IYICIIIIII~ opc~ration
High voltage high vacuum feedthrough Veeco Instruments Inc, USA, have announced the availability of their DFT high voltage, high vacuum feedthrough as a separate item. The feedthrough is usually incorporated in model VeB6 electron beam 662
ntcttthcr
52 on Rcurkw
Et‘nqrriry
Scrr~iw
knife-edge bearing at the top of the frame and linked to the moving contact htcms of lhc switches, and to the tight auxiliary contacts mounted on the front of the frame. Universal joints locate the VKLILII~ hwitchch in position so that the contacts move linearly despite the slight rotary movement of the armature. Careful design ensures that the relative movements of the vacuum switches, magnetic cores and auxiliary COW tacts are provided by the single lever armature. A dc magnetic system is used to reduce noise and wear. Power interruptions are almost inaudible, the only significant sound being the opening and closing of the armature. For three phase direct-on motel starting duties the vacuum switches are designed to complete at least two million operations on full load before replacement, and the contactors will complete at least ten million mechanical operations. In contrast, it is usual to check and maintain conventional oil or air-break contactors every 100.000 operations and rcolacement of the main contacts is often’ required uftel 250,000 operations. Performance has been tested satisfactorily at operating rates LIP to 7200 an hour. A major feature of the vacuum contaclor is the absence of current chopping-the vacuum switch breaks the circuit when the first zero in the current waveform is reached, so high voltage transients are not created. This facilitv is important in modern electronically-&ntrolled industrial plants. The elimination of arc chutes enables the size of the new vacuum contactors to be reduced to two-fifths of the volume of an equivalent air-break contactor. Each unit measures 8: inches high by 91 wide and 9.1 deep and weighs 25 lb. This compact size is advantage& in the design of flameproof enclosures. The Cact that- the arcs ‘are contined within the vacuum switch envelopes is an advantage for hazardous areas. An important pal-t of the development programme has been the assignment of ratings in accordance with the International Electrotechnical C‘ommission IECl58 Part I and VDE0660 soecifications. as well as BS775 : 1956.
AEI, Control ‘Equipment Division, UK Circlr trvttrhrr 53 ott Rccttkr Ettqrriry~ .Sc,t,viw (Wtl
Advanced vacuum contactors
Automatic liquid nitrogen refiller
Since the introduction of vacuum contactors in 1965, AEI have opened successful application fields throughout the process industries and in steel works, mines, cement plants, quarries and other exacting environments. AEI Control Equipment have recently announced the development of new types of vacuum contactors: rated at 220 A, 660 V for medium-size motor starting duty (up to I75 hp at 440 V); and I50 A. II00 V for mining applications. This is the first time that the advantages of vacuum contactor control devices (reliability, minimum maintenance and compactness) have been extended to these widespread and important uses. Each unit has a durable and rigid polyester resin-bonded, glass-filled moulded plastic frame carrying three AEI vacuum switches. An armature operated by two magnet coils is hinged on a
Leybold-Heraeus have developed an automatic refiller, working either mechanically or electrically, for maintaining the level of the liquid in a dewar vessel, cryostat or cold trap. This device extends the working periods of vacuum systems, particularly mercury diffusion pumped systems. A tenlitre storage tank for liquid nitrogen is also available for the refiller. Ten litres of nitrogen will allow unattended operation ol the Quick 100 pump (mercury diffusion) for 40 hours, the Quick 500 for 20 hours and the Quick 2000 for IO hours. The cold traps of the 100 and 500 Quick pumps may have either mechanical or electrical rcfilling but those of the 2000 and 8000 pumps can only be electrically refilled. In the mechanical unit, operation is by a methane-filled bellows and sensing probe which dips into the trap. While the probe
Vacuum news
good corrosion resistance. Nickel is superior to stainless steel in solderability and weldability and should find many applications in research laboratories. Specifications and prices are the same as for stainless steel Flexpand. The company is also offering ceramic insulator blocks (2 x 2 x 1 inch) in high grade steatite. Female threads are situated at each end of the blocks facilitating mounting and connections. These insulator blocks are unusually low-priced and may be used in the construction of substrate heaters, electron beam guns, thin film sources, nude Bayard-Alpert gauges etc. Mason-Renshaw, USA Circle number 56 on Reader Enquiry Service card Automatic liquid nitrogen refilfer
is submerged, methane is condensed in the bellows and an air vent valve is kept open. When the coolant level drops to uncover the probe, the rise in temperature evaporates some methane, expanding the bellows to close the air-vent valve. Excess pressure then forces the liquid nitrogen through a vacuum-jacketed feed tube into the trap. In the electrical unit, a semiconductor diode replaces the mechanical probe and temperature change causes a change in resistance. The diode is part of a bridge circuit controlling a magnetic valve which effects the refilling in a manner similar to the mechanical unit. For both systems, an adaptor is available which takes the excess nitrogen on overfilling, thus keeping coolant losses down to a minimum. Leyhold-Heraeus Ltd, UK Circle number 54 on Reader Enquiry Service card 2000 Gallon liquid helium dewar
Gardner Cryogenics Corp, USA, have introduced a 2000 gallon liquid helium dewar designed for over-the-road shipment of bulk quantities of liquid helium. The dewar is constructed of a stainless steel inner helium vessel which is thermally insulated from the carbon steel outer shell by a combination of high vacuum and liquid nitrogen. The inner vessel is specially shock mounted to protect it from the stresses and strains normally encountered during handling and hauling. The dewar is 18 ft 10 inches long, has a diameter of 6 ft 8 inches and a height of 6 ft 10 inches. The dewar weighs 8700 pounds empty and when fully loaded weighs 11,015 pounds. Maximum allowable working pressure for helium is 40 psig and for LN2, 10 psig. Boil off rate is 1 per cent per day. Gardner Cryogenics Corporation, USA Circle number 55 on Reader Enquiry Service card
Flexible nickel tubing Mason-Renshaw of California, USA, have announced the availability of their Flexpand metal tubing in pure nickel. The tubing was previously only available in type 321 stainless steel. The nickel tubing is easily degassed, spot-welded or joined to other parts by hard or soft solder, and has
Pumping of food products The transfer of difficult-to-handle liquids and semi-solids such as fruit pulps, soups and delicate liquids, which may be damaged by conventional pumping,is effectively Gardner’s 2000 gallon liquid helium dewar
performed indirectly using a Megator air displacement unit so that the products do not pass through the pump. A standard Megator sliding-shoe pump operates as an oil-free exhauster/compressor unit connected to a pressure/vacuum vessel with appropriate valving. During the suction cycle, air is drawn from the product vessel and discharged to exhaust, filling the vessel with the product. During discharge, air is drawn through a suction filter and compressed in the vessel to displace the product. A high level cut-out to stop the exhauster/ compressor unit automatically when the vessel is full is available as an ontional extra. The Megator air displacement units provide a simple, effective solution to this transfer problem and are available in a range of capacities to suit many applications. Megator Pumps and Compressors Ltd, UK Circle number 57 on Reader Enquiry Service card
Solution of an internal glazing problem The problem of passing a 10 ft 8 inch x 12 ft sheet of b inch plate glass (weighing 640 lb) through a shallow window opening, in a new office block in South East London. was solved by using a lorry-mounted crane fitted with vacuum equipment. Aygee (Glass) Ltd.. glazing contractors for the building,. were-able io tilt the glass at an angle which allowed it to pass between the transomes of the window opening. The glass sheet was required as an internal screen and once inside the building the beam was turned through 90 degrees to bring the plate into correct alignment for fixing. Aygee (Glass) Ltd, UK Circle number 58 on Reader Enquiry Service card
Solution of Aygee’s glazing problem by means of a suction device