Dry vacuum pump is a kind of mechanical vacuum pump which can start pumping under atmospheric pressure, and can directly discharge the pumped gas into the atmosphere. There is no oil or other working medium in the pump cavity, and the pump’s limit pressure is equal to or close to that of oil-sealed vacuum pump.
After years of industrial application of high vacuum system development, we often take oil diffusion pump as the main vacuum pump, oil seal mechanical pump as the front pump to form a universal high vacuum system, that is, the so-called wet vacuum system. For the vacuum pump of this system, it is clearly pointed out that it is not suitable for the extraction of gases containing excessive O2, explosive, corrosive, chemical reaction to pump oil and particles of dust. Why are there restrictions on gas extraction? It is because there is oil in the pump.
However, modern industrialization requires higher requirements. Under clean conditions, only air or a little water vapor is pumped. Under medium conditions, reactive gases are pumped out, but no solid particles are produced. Under adverse conditions, chemical reactants (toxic or even carcinogenic) and solid particles are pumped out.
In order to meet the requirements of different application fields and different working conditions, foreign countries have multi-stage Roots vacuum pump, multi-stage claw vacuum pump, screw vacuum pump, scroll vacuum pump, reciprocating piston vacuum pump and turbine oil-free vacuum pump. The limit pressure is 10-10-2 Pa and the pumping speed is 20-500 m3/h. However, the application of domestic dry pumps is less than 3% at present. All the domestic semi-conductor dry pumps are imported from abroad, and their prices are very expensive. Therefore, China should study and develop dry pumps vigorously to make dry pumps become a new economic growth point of vacuum industry in China.
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