Mechanical selection of vacuum pumps

(1) Whether the vibration generated during the operation of the vacuum pump has any impact on the process and environment. If the process does not allow, choose a non-vibration pump or take anti-vibration measures.
(2) Understand the composition of the pumped gas, whether the gas contains condensable vapor, whether there is particulate dust, whether it is corrosive, etc. When selecting a vacuum pump, it is necessary to know the gas composition and select the corresponding pump for the pumped gas. If the gas contains vapors, particles, and corrosive gases, you should consider installing auxiliary equipment on the inlet pipeline of the pump, such as condensers, dust collectors, etc.
(3) Under its working pressure, the vacuum pump should be able to discharge all the gas generated in the process of vacuum equipment.
(4) Correctly combine vacuum pumps. Because the vacuum pump selectively pumps, sometimes the selection of a pump can not meet the pumping requirements, and several pumps need to be combined and complement each other to meet the pumping requirements. For example, the titanium sublimation pump has a high pumping speed for hydrogen, but can not pump helium, and the three-pole sputtering ion pump, (or two-pole asymmetric cathode sputtering ion pump) has a certain pumping speed for argon, and the combination of the two will make the vacuum device get a better vacuum. In addition, some vacuum pumps cannot work at atmospheric pressure and need to be pre-vacuumed; Some vacuum pump outlet pressure is lower than atmospheric pressure, and a backing pump is required, so the pump needs to be combined for use.
(5) Requirements for oil pollution in vacuum equipment. If the equipment strictly requires oil-free, various oil-free pumps should be selected, such as: water ring pump, molecular sieve adsorption pump, sputtering ion pump, cryogenic pump, etc. If the requirements are not strict, you can choose to have an oil pump, plus some anti-oil pollution measures, such as adding cold traps, baffles, oil traps, etc., which can also meet the requirements of clean vacuum.
(6) Correctly select the working point of the vacuum pump. Each pump has a certain working pressure range, such as: 2BV series water ring vacuum pump working pressure range 760mmHg ~ 25mmHg (absolute pressure), in such a wide pressure range, the pumping speed of the pump changes with the pressure (the detailed change refers to the performance curve of the pump), and its stable working pressure range is 760~60mmHg. Therefore, the working point of the pump should be selected within this range, and it should not be allowed to work for a long time under 25~30mmHg.