Consider a vacuum system with a vacuum pump which, at first, according to the requirements of the system, followed by the performance characteristics of the pump to respond in detail to understand, compare the advantages and disadvantages of various pumps, and then decide it, so as to get the proper choice. To facilitate the selection of a vacuum pump to be used, now China’s production of various types of vacuum pumps at the overall situation summarized briefly compare their characteristics, advantages and disadvantages, it seems necessary.
First, the mechanical pump seals
Is the production of 2X type are two-stage rotary vane pump, pumping speed of 0.5 to 150 l / s, there is a full range of products.
Sub-single-stage rotary piston pump (H-type), two-stage (2H type). Pumping speed: H type 8 to 600 l / s; 2H type 8 to 70 liters / sec. There are a series of products.
Trochoidal pump pumping speed can be very large, small, and is currently trial production.
Such pumps are used for obtaining a low vacuum, or as a high vacuum pump before the pump and pre-pumped. With gas ballast device can be exhausting humid air. But the ultimate vacuum than pumping dry air (when no gas town) an order of magnitude lower. Pumping speed refers to the import of 760 Torr pressure when pumping speed, when the system pressure drop pumping speed also decreased, until close to the ultimate vacuum pump, pumping speed is also close to zero. Its pumping off coefficient certain requirements
Second, the mechanical booster pump (Roots pump)
Working pressure range 10 ~ 5×10-4 Torr, commonly range 2 ~ 5×10-3 Torr, pumping speed range from 150 to 2000 liters / sec, China has a series of products. This pump maximum pumping speed at 2 torr to 10-2 torr, before the pump needs, not directly to the exhaust air. Ultimate vacuum pump with pre-change. Compared with oil booster, working pressure range is wide, maximum discharge pressure is high (10 to 30 Torr mechanical booster, booster pump oil 1 to 2 torr), regurgitation of oil vapors rarely use it pumping In addition to containing water vapor and other condensable gases more appropriate.
Third, oil booster
Working pressure range 1 ~ 1×10-4 Torr, commonly in the range of 0.1 ~ 1×10-2 Torr, pumping speed range from 200 to 40,000 l / sec, to make up for mechanical pump, diffusion pump pumping speed small defect in this pressure range. Inert gas and other gases have the same pumping speed.
Fourth, the oil diffusion pump
Ordinary oil diffusion pump working pressure range 10-2 ~ 5×10-7 Torr, commonly range 10-8 ~ 5×10-6 Torr, pumping speed range of 20 to 100,000 liters / sec, metal, glass structures are diffusion pumps in series production. Ultra-high vacuum oil diffusion pump ultimate pressure of about 10-10 torr, in addition to the general structure and a little oil diffusion pump slight differences, the main difference is the working fluid, different structural materials, such as silicone oil that is used as a pump fluid 275, structural materials stainless steel. Ultrahigh vacuum on the large differences in the new design.