Several methods for choosing a vacuum pump were introduced before, and today I will continue to introduce other methods.
Select the vacuum unit:
(1) When one type of pump cannot meet the requirements of pumping and vacuum, it is necessary to combine several pumps to complement each other to meet the process requirements.
(2) Some vacuum pumps cannot work under atmospheric pressure and require pre-vacuum; some vacuum pumps have outlet pressure lower than atmospheric pressure and require backing pumps, so they all need to be used in combination. The vacuum pump used in combination is called a vacuum pump unit, which can make the vacuum system obtain better vacuum degree and exhaust volume. We should choose the combined vacuum pump correctly, because different vacuum pumps have different requirements for the gas to be pumped out. For example, in general, the Roots-rotary vane unit is not suitable for systems containing more condensable gases.
When you choose an oil-sealed pump, you should first understand whether your vacuum system has requirements for oil pollution. If the equipment is strictly required to be oil-free, various oil-free pumps should be selected, such as: water ring pumps, cryogenic pumps, etc. If the requirements are not strict, you can choose an oil pump, plus some anti-oil pollution measures, such as adding cold traps, oil traps, baffles, etc., can also meet the clean vacuum requirements.
