The type of pump is mainly determined by the amount of gas required for the job, the degree of vacuum, the pressure of the exhaust gas. Pump work, you need to pay attention to the following two aspects:

1.as far as possible in the high efficiency area, that is, in the critical vacuum degree or the critical exhaust pressure of the region within the operation.

2.should be avoided in the vicinity of the maximum vacuum degree or maximum exhaust pressure operation. In this area, not only the efficiency is very low, but the work is not stable, it is easy to produce vibration and noise. For the vacuum pump with a high degree of vacuum, the operation of the area will often occur, the phenomenon of cavitation, the obvious signs of this phenomenon is that there is noise and vibration in the pump. Cavitation will cause the pump body, impeller and other parts of the damage, so that the pump can not work.

According to the above principle, when the vacuum degree or gas pressure required by the pump is not high, it can be a priority in the single stage pump. If the vacuum degree or exhaust pressure is higher, the single stage pump can not meet the requirements, or, in the case of high vacuum pump, there is still a large amount of gas, that is, the performance curve in the higher vacuum degree is relatively flat, can choose two pumps. If the vacuum degree in 710mmHg above, choose water ring air pump or water ring - roots vacuum units for for vacuum pumping device. If only for the use of a vacuum pump, it is better to use a single acting pump. Because of the simple structure of the single acting pump, easy to manufacture and maintenance, and in high vacuum conditions of good anti cavitation. If only for the use of the air compressor, it is appropriate to use the dual role of the pump.

Because of the dual role of large volume, small volume, light weight, radial force can be automatically balanced, shaft is not easy to produce fatigue fracture, the use of long life pump.