Refrigeration – Low pressure cold trap process and apparatus
Patent
1989-09-07
1990-12-11
Caposseio, Ronald C.
Refrigeration
Low pressure cold trap process and apparatus
55269, 62268, 417901, B01D 800
Patent
active
049761110
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to vacuum technology and more specifically to the designs of cryogenic condensation vacuum pumps. The best use of the invention may be made in vacuum technology widely employed in the electronic industry, radio engineering and other industries, as well as in those fields of research which need creating and maintaining, for a long time, an ultrahigh-purity, completely oil-free ultrahigh vacuum in the operating pressure range from 1.times.10.sup.-4 to 1.times.10.sup.-10 Pa.
DESCRIPTION OF THE PRIOR ART
At present, the improvement of cryogenic condensation pumps follows the path of optimization of their designs with the purpose to reduce their weight and metal consumption, simplify the processes of pump assembly and disassembly, and improve the pump efficiency.
Known in the art is a cryogenic condensation pump containing a housing, accommodating a radiation shield comprised of a vessel for a cryoagent, a shell heat line and a chevron baffle that are properly interconnected and a pump-out element in the form of a vessel. The vessel for the cryogent of the radiation shield and the pump-out element are provided with suspension pipes serving to fill said vessels with cryoagents, respectively, liquid nitrogen and liquid helium, as well as to secure the vessels in the housing (M. P. Larin, "Pribory i Tekhnika Eksperimenta", a journal of the Academy of Sciences of the USSR, Moscow, No. 2, 1982, pp. 130-133, cf. p. 132).
It is known that of primary importance in helium cryogenic condensation pumps is the problem of economically efficient consumption of liquid helium for reasons of its scarcity and high price. However, in the pump described, the pump-out element made of copper and filled with liquid helium experiences large heat inflows along a smooth-walled suspension pipe. Therefore, in the pump described, relatively high vaporability of the liquid helium exists, with the result that this pump design is not sufficiently economical.
Also known in the art is a cryogenic condensation pump containing a housing accommodating a radiation shield comprised of a vessel for a cryogent, a shell heat line and a chevron baffle that are properly interconnected, and a pump-out element in the form of a vessel (SU, A, 1017817). The pump-out element is in the form of a vessel and is located in the cavity formed by the bottom of the vessel for the cryoagent of the radiation shield, the surface of the shell heat line and the chevron baffle. The vessel for the cryoagent of the radiation shield and the pump-out element are provided with suspension pipes serving to fill said vessels with cryoagents, namely liquid nitrogen and liquid helium, respectively, as well as to secure these vessels in the housing. To reduce heat inflows to the pump-out element filled with liquid helium through a suspension pipe, the latter is made in the form of a corrugated metal tube with a helical corrugation profile. Suspension pipes are joined by welding to the vessel for the cryoagent of the radiation shield or to the pump-out element. To join the suspension pipes to the housing, their top ends are welded to the top ends of the housing branch pipes into which the suspension pipes are inserted. The pump housing and suspension pipes are made of stainless steel and the elements of the radiation shield, i.e., the cryoagent vessel, shell heat line and chevron baffle, as well as the pump-out element, of copper.
A disadvantage of this pump is that its assembly or disassembly presents difficulties, e.g., in repairs of the vessel for the cryoagent of the radiation shield or the pump-out element. In such cases, the top ends of suspension pipes and of housing branch pipes welded together must be cut and, upon completion of repair and subsequent reassembly of the pump, they must be rewelded so as to provide highquality welds of the pipe ends. These operations are labour- and time-consuming and require special conditions. Besides, pump elements of stainless steel and copper mean heavy weight and metal consumption, r
REFERENCES:
patent: 3144200 (1964-08-01), Taylor et al.
patent: 3256706 (1966-06-01), Hansen
patent: 3263434 (1966-08-01), Eder
patent: 3304731 (1967-02-01), Bills et al.
patent: 3485054 (1969-12-01), Hogan
patent: 3625018 (1971-12-01), Roberts
patent: 3712074 (1973-01-01), Boissin
patent: 4356701 (1982-11-01), Bartlett et al.
Obschaya Experimentalnaya Tekhnika
LandOfFree
Cryogenic condensation pump does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cryogenic condensation pump, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cryogenic condensation pump will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-382652