Molecular formula :
nature : pumping gas (or vapor) for the vacuum device. Can be divided into : (a) dry vacuum pumps, only from the suction container of gas, they can achieve 96% to 99.9% vacuum; (2) wet vacuum pumps, pumping gas at the same time, with more water vapor, it can only produce 80% ~ 85% vacuum. Under the structure can be divided into reciprocating vacuum pumps, rotary vane vacuum pump and water ring vacuum pump. For vacuum evaporation and vacuum distillation, vacuum filter operating.
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