How to cleverly choose a vacuum pump?

1. The working pressure of the vacuum pump should meet the vacuum limit and working pressure requirements of the vacuum equipment. For example, vacuum coating requires a vacuum degree of 110-5mmHg, and the selected vacuum pump should have a vacuum degree of at least 510-6mmHg. The vacuum degree of the pump is usually chosen to be half to one order of magnitude higher than the vacuum degree of the vacuum equipment.

2. Choose the working point of the vacuum pump correctly. Each type of pump has a certain working pressure range, such as a diffusion pump with a pressure range of 10-3~10-7mmHg. Within this wide pressure range, the pump's pumping speed varies with pressure, and its stable working pressure range is 510-4~510-6mmHg. Therefore, the working point of the pump should be selected within this range, and it cannot be operated for a long time at 10-8mm Hg. For example, a titanium sublimation pump can operate at 10-2mmHg, but its working pressure should be less than 110-5mmHg.

3. The vacuum pump should be able to discharge all the gas generated during the vacuum equipment process at its working pressure. 4. Correctly combine the vacuum pump. Due to the selective pumping of vacuum pumps, sometimes selecting one type of pump cannot meet the pumping requirements. Several pumps need to be combined and complemented to meet the pumping requirements. A titanium sublimation pump has a high pumping speed for hydrogen, but cannot pump helium, while a type III sputtering ion pump (or a type II asymmetric cathode sputtering ion pump) has a certain pumping speed for argon. When combined, the vacuum device can achieve a better vacuum degree. In addition, some vacuum pumps cannot operate at atmospheric pressure and require pre vacuum; Some vacuum pumps have an outlet pressure lower than atmospheric pressure and require a front stage pump, so they need to be combined for use.

5. Requirements for oil pollution in vacuum equipment. If the equipment strictly requires oil-free operation, various oil-free pumps should be selected, such as water ring pumps, molecular sieve adsorption pumps, sputtering ion pumps, low-temperature pumps, etc. If the requirements are not strict, you can choose to have an oil pump and add some oil pollution prevention measures, such as adding a cold trap, baffle, oil blocking trap, etc., which can also meet the requirements of clean vacuum.

6. Understand the composition of the extracted gas, whether the gas contains condensable vapor, whether there is particulate dust, and whether it is corrosive. When choosing a vacuum pump, it is necessary to know the gas composition and select the corresponding pump for the extracted gas. If the gas contains steam, particles, and corrosive gases, it should be considered to install auxiliary equipment such as condensers, dust collectors, etc. on the inlet pipeline of the pump.

7. How does the oil vapor discharged from the vacuum pump affect the environment. If pollution is not allowed in the environment, you can choose an oil-free vacuum pump or discharge the oil vapor outdoors.

8. Does the vibration generated during the operation of the vacuum pump have any impact on the process and environment. If the process does not allow it, a vibration free pump should be selected or anti vibration measures should be taken.

9. The price, operation, and maintenance costs of vacuum pumps.