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   Vacuum pump is a kind of device that produces, improves and maintains vacuum in a certain enclosed space by various methods. Vacuum pump can be defined as: using mechanical, physical, chemical or physicochemical methods to pump the container to obtain vacuum devices or equipment. With the development of vacuum application, there are many kinds of vacuum pumps, whose pumping speed is from 0.0 liters per second to hundreds of thousands or millions of liters per second.

   According to the working principle of vacuum pump, vacuum pump can be basically divided into two types, namely variable volume vacuum pump and momentum transfer pump.