(1) Roots vacuum pump with pressure stabilizing box: the rotor profile of this kind of roots pump has arc type, involute type and combined type. It has been described in detail before, but it will not be described here. The difference between this pump and dry roots pump is that it can be directly discharged into the atmosphere without the front stage pump and cooled with water instead of air cooling. A pressure stabilizing box is installed at the mouth of the pump shell, It has the effect of noise elimination and voltage stabilization, and is very convenient to use.
(2) Roots vacuum pump with separators and silencers for direct discharge to the atmosphere: the structure, working principle and rotor profile of this roots vacuum pump are completely the same as those mentioned above. It is also a so-called wet roots vacuum pump with water cooling and direct discharge to the atmosphere with a front stage pump; The difference is that there is no pressure stabilizing box on the inlet of the pipeline, but a gas-water separator is installed on the pipeline of the inlet port, while a separation and muffler are installed on the pipeline of the entrance of * * to achieve the effect of gas water separation and noise elimination. Now, this kind of equipment is widely used in foreign countries.