Precautions for selecting vacuum pump

1. The working pressure of vacuum pump shall meet the requirements of extreme vacuum and working pressure of vacuum equipment. For example, a vacuum drying process requires a working vacuum of 10mmhg, and the limit vacuum of the selected vacuum pump should be at least 2mmhg, preferably 1mmhg. Generally, the extreme vacuum degree of the pump is half to one order of magnitude higher than the working vacuum degree of the vacuum equipment.

2. Correctly select the working point of the vacuum pump. Each pump has a certain working pressure range. For example, the working pressure range of 2BV series water ring vacuum pump is 760mmhg ~ 25mmhg (absolute pressure). Within such a wide pressure range, the pumping speed of the pump changes with the pressure (refer to the pump performance curve for details), and its stable working pressure range is 760 ~ 60mmhg. Therefore, the working point of the pump should be selected within this range, rather than working for a long time under 25 ~ 30mmhg.

3. Under its working pressure, the vacuum pump shall be able to discharge all the gas generated in the process of vacuum equipment.

4. Combine the vacuum pump correctly. Because the vacuum pump has selective pumping, sometimes one pump can not meet the pumping requirements. Several pumps need to be combined and supplemented to meet the pumping requirements. For example, the titanium sublimation pump has a high pumping speed for hydrogen, but can not pump helium, while the three pole sputtering ion pump (or the two pole asymmetric cathode sputtering ion pump) has a certain pumping speed for argon. If the two are combined, the vacuum device will obtain a better vacuum degree. In addition, some vacuum pumps can not work under atmospheric pressure and need pre vacuum; The outlet pressure of some vacuum pumps is lower than atmospheric pressure, and the front stage pump is required, so the pumps need to be combined for use.

5. Requirements for oil pollution of vacuum equipment. If the equipment is strictly required to be free of oil, various non oil pumps should be selected, such as water ring pump, molecular sieve adsorption pump, sputtering ion pump, cryogenic pump, etc. If the requirements are not strict, an oil pump can be selected, and some oil pollution prevention measures, such as adding cold trap, baffle, oil trap, etc., can also meet the requirements of clean vacuum.

6. Understand the composition of the extracted gas, whether the gas contains condensable steam, whether there is particulate dust, whether it is corrosive, etc. When selecting a vacuum pump, you need to know the gas composition and select the corresponding pump for the pumped gas. If the gas contains steam, particles and corrosive gas, it should be considered to install auxiliary equipment on the air inlet pipeline of the pump, such as condenser, dust collector, etc.

7. How does the oil vapor discharged by the vacuum pump affect the environment. If the environment is not allowed to be polluted, oil-free vacuum pump can be selected, or the oil vapor can be discharged outdoors.

8. Whether the vibration generated during the operation of the vacuum pump has an impact on the process and environment. If the process is not allowed, the pump without vibration shall be selected or anti vibration measures shall be taken.

9. Price, operation and maintenance cost of vacuum pump.