The function of vacuum pump is to remove gas molecules from the vacuum chamber, reduce the gas pressure in the vacuum chamber, and make it reach the required vacuum degree.

Generally speaking, there is a large range from the atmosphere to the extremely high vacuum, which has not been covered by a vacuum system so far.

Therefore, in order to meet the requirements of process index, work efficiency and equipment service life of different products, different vacuum section needs to choose different vacuum system configuration.

In order to achieve the best configuration, the following points should be considered when selecting the vacuum system:

1. Determine the working vacuum range

First, the vacuum degree required by each process must be checked and determined. Because each process has its own suitable vacuum range, it must be carefully studied and determined.

2. Determination of limiting vacuum

On the basis of determining the vacuum degree required by the process, the limit vacuum degree of the vacuum pump system is checked, because the limit vacuum degree of the system determines the best working vacuum degree of the system.

Generally speaking, the limit vacuum degree of the system is 20% lower than the working vacuum degree of the system and 50% lower than that of the previous stage pump.

3. Selection and calculation of main vacuum pump

s=2.303v/tlog(p1/p2)

Where: s is the pumping rate of vacuum pump, V is the volume of vacuum chamber, t is the time required to reach the required vacuum degree, P1 is the initial vacuum degree, P2 is the required vacuum degree.

4. Vacuum volume

Check to determine the time required to achieve the required vacuum degree, flow resistance and leakage of the vacuum pipe.

The pumping rate required to maintain vacuum under certain process conditions after reaching the required vacuum degree is considered.

5. Type and volume of gas to be pumped

Check and determine the type and amount of air extraction required by the process. Because if the type of gas to be pumped reacts with the liquid in the vacuum pump, the pump system will be contaminated. At the same time, it is necessary to determine the appropriate exhaust time and the amount of gas produced during the extraction process.