The types of vacuum pumps purchased are mainly determined by the amount of air pumped, the vacuum degree or the exhaust pressure required by the customers when they work. When choosing vacuum pump, we need to pay attention to the following two aspects.
When choosing a vacuum pump, it is necessary to use it in the high efficiency area, that is, in the area of critical vacuum or critical exhaust pressure.
At the same time, it should avoid operating near the maximum vacuum or exhaust pressure. Operating in this area, not only the efficiency is very low, but also the work is very unstable, easy to produce vibration and noise. Therefore, when purchasing vacuum pumps and vacuum pumps, it is recommended that manufacturers or professionals select the type. The parameters of vacuum pump are only for reference.
At the same time, when the vacuum pump operates in high vacuum for a long time, cavitation often occurs in the high vacuum region. The obvious sign of this phenomenon is that there is noise and vibration in the pump. Cavitation will cause damage to pump body, impeller and other parts, so that the pump can not work.
According to the above principles, when the vacuum or gas pressure required by the vacuum pump is not high, it can be preferentially selected in the single-stage pump. If the vacuum or exhaust pressure is high, the single stage pump can not always meet, or the vacuum pump is still required to have a larger air volume at a higher vacuum, that is to say, the performance curve is flat at a higher vacuum, so the two stage pump can be chosen. If the vacuum requirement is above – 710mmHg, the vacuum pump and air ejector or Roots water ring vacuum unit can be selected as the vacuum pumping device.
If it is only used as a vacuum pump, it is better to choose a single-stage vacuum pump. Because the structure of single stage vacuum pump is simple, easy to manufacture and maintain, and it has good cavitation resistance in high vacuum. If it is used only for compressors with larger air volume, it is more appropriate to choose two-stage vacuum pump. Because of the large volume, small volume and light weight of the two-stage vacuum pump, the radial force can be automatically balanced, the shaft is not easy to produce fatigue fracture, making the service life of the vacuum pump longer.
Vacuum pumps are selected according to the volume of air required by the system. After preliminary selection of the type of vacuum pumps, the type of vacuum pumps should be selected according to the volume of air required by the system to purchase the vacuum pumps.