How to Choose Suitable Vacuum Pumps

Basis and Conditions


  • System requirements for vacuum degree 

According to the system's requirements for vacuum degree, select the corresponding vacuum pump. Generally, the ultimate vacuum of the pump is required to be higher than the ultimate vacuum required by the system.


  • Pressure range during normal operation of the system

The normal working pressure range of the pump must meet the working pressure required by the system.


  • The type, composition, impurity situation of the air and the pollution restriction requirements during system operation

The nature of the pumped gas and the requirements for pollution are an important condition for selecting vacuum pumps. It is not only related to the performance of the pump at work, but also directly related to the working life and maintenance of the pump. Especially in chemical production, it is often a key factor in the correct selection of the pump.


  • The suction capacity or volume flow

It is the main basis to choose a certain type of vacuum pump.


Selection of Vacuum Pump and Calculation of Pumping Speed


  • Calculate the effective pumping speed “S”(L/s) of the vacuum pump.

Calculate the effective pumping speed of the pump according to the working pressure “p”g required by the vacuum system and the total gas volume “Q” of the vacuum system. 


“Q” is the total gas volume of the vacuum system, including the volume of gas generated during the working process, the gas release volume of the vacuum system and vacuum components, and the total leak volume of the vacuum system.

Usually increase the effective pumping speed by 20%~30% or more as the nominal pumping speed of the main pump.


  • Determine the pumping speed of the vacuum pump

The pumping speed “Sp” of the main pump is determined according to the effective pumping speed “S” and the conductance “U” of the connecting pipe between the pump and the vacuum chamber.



  • Choose a vacuum pump according to the type, composition, temperature of the gas, and the dust and impurities condition in the gas.

  • According to the different requirements of the vacuum chamber for oil pollution, choose oil, oil-free, semi-oil-free, dry, and wet vacuum pumps.

Dry vacuum pumps are suitable for occasions that require absolutely no oil or working fluid, or where the storage and processing costs of working fluid are concerned.


  • Choose pump according to the economic indicators of investment and daily maintenance and operation.


If you want to learn more news about pumps and vacuum industry, please read these blog posts.


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