(1) Classification according to the working principle of vacuum pump
① pumping type: vacuum pump sucks the gas in the system and exhausts the gas molecules out of the system.
② capture type. The gas molecules in the vacuum pump capture system are directly adsorbed on the working wall of the pump without discharging the system.
(2) Classification by vacuum pump structure
① mechanical type. This kind of vacuum pump is similar to the compressor, which belongs to the volume type of reciprocating and rotary structure, and also belongs to the power type of turbine molecular pump, which are all pumping vacuum pumps.
② jet pump. There are two forms of jet pump and diffusion pump, as well as the booster pump which combines the two together, which are also pumping vacuum pumps.
③ suction type. The utility model relates to a trapping vacuum pump, in which the gas molecules are adsorbed on the surface of the pump wall by physical or chemical methods.
(3) According to the function of vacuum pump in the system
① main air extraction pump. The main working pump to achieve the required pressure.
② pre extraction pump. When the main air pump can not directly start pumping in the atmospheric state, it needs to pump to a certain pressure before the main air pump can work.
③ front stage pump. When the main air extraction pump can not directly discharge the extracted gas into the atmosphere, it is necessary to connect the front pump in series to discharge.
④ maintain the pump. When the main air extraction pump finishes the required pressure stop work, the pressure may rise due to system leakage or surface evaporation and other reasons, so use the maintenance pump to continue pumping.