How to choose the type of vacuum pump?
I. the type of vacuum pump is mainly determined by the air volume, vacuum degree or exhaust pressure required for operation.
When the vacuum pump works, the following two aspects should be paid attention to:
As far as possible, it is required to operate in the high efficiency area, that is, the area with critical vacuum degree or critical exhaust pressure.
Avoid operation near the maximum vacuum or exhaust pressure. In this area, not only the efficiency is very low, but also the work is very unstable, easy to produce vibration and noise. For vacuum pumps with high vacuum degree, cavitation often occurs when they operate in this area. The obvious sign of this phenomenon is that there is noise and vibration in the vacuum pump. Cavitation will cause damage to vacuum pump body, impeller and other parts, so that the vacuum pump can not work.
According to the above principles, when the vacuum degree or gas pressure required by the vacuum pump is not high, it can be selected preferentially in the single-stage vacuum pump. If the vacuum degree or exhaust pressure is high, the single-stage vacuum pump is often unable to meet the requirements, or the vacuum pump is required to have a large amount of gas under the condition of high vacuum degree, that is, the performance curve is required to be relatively flat under the condition of high vacuum degree, so the two-stage vacuum pump can be selected. If the vacuum degree is required to be more than - 710mmhg, water ring atmosphere vacuum pump or water ring roots vacuum unit can be selected as the vacuum pumping device.
If it is only used for vacuum pump, it is better to choose single acting vacuum pump. Because the single acting vacuum pump is simple in structure, easy to manufacture and maintain, and has good cavitation resistance under high vacuum.
If it is only used for compressor with larger air volume, it is suitable to select double acting vacuum pump. Because the double acting vacuum pump has large air volume, small volume and light weight, the radial force can be automatically balanced, the shaft is not easy to produce fatigue fracture, and the service life of the vacuum pump is long.
II. Select vacuum pump according to the air volume required by the system
After the type of vacuum pump is preliminarily selected, the model of vacuum pump shall be selected according to the air volume required by the system.