The type of pump is mainly determined by the air volume, vacuum degree or exhaust pressure required for work.

When the pump is working, you need to pay attention to the following two aspects:
1. As far as possible, it is required to operate in the high-efficiency area, that is, in the area of ​​critical vacuum or critical exhaust pressure.
2. Avoid running near the vacuum or exhaust pressure. Running in this area is not only inefficient, but also very unstable, prone to vibration and noise. For vacuum pumps with a high degree of vacuum, cavitation often occurs when operating in this area. The obvious sign of this phenomenon is noise and vibration in the pump. Cavitation will cause damage to the pump body, impeller and other parts, making the pump unable to work.

According to the above principles, when the vacuum degree or gas pressure required by the pump is not high, the single-stage pump can be selected first. If the vacuum degree or exhaust pressure is high, the single-stage pump is often unable to meet the requirements, or the pump is required to still have a large gas volume under the condition of a higher vacuum degree, that is, the performance curve is required to be flat at a higher vacuum degree. Two options are available. Stage pump. If the vacuum is required to be above -710mmHg, a water ring-atmospheric pump or a water ring-Roots vacuum unit can be selected as the vacuum device.

If it is only used as a vacuum pump, it is better to use a single-acting pump. Because the single-acting pump has a simple structure, is easy to manufacture and maintain, and has good cavitation resistance under high vacuum conditions. If it is only used as a compressor with a larger capacity, a double-acting pump is more appropriate. Because the double-acting pump has large air volume, small size and light weight, the radial force can be automatically balanced, the shaft is not prone to fatigue fracture, and the pump has a long service life. The vacuum pump is selected according to the gas volume required by the system. After the pump type is initially selected, for the vacuum pump, the pump model should also be selected according to the gas volume required by the system.