How to Select Vacuum Pump
1. The working pressure of the vacuum pump should meet the requirement of the limit vacuum and working pressure of the vacuum equipment. For example, the vacuum coating needs a vacuum of 1 x 10-5 mm Hg, and the vacuum of the selected vacuum pump must be at least 5 x 10-6 mm Hg. The vacuum of the pump is usually chosen to be half the order of magnitude higher than that of the vacuum equipment.
2. Choose the working point of vacuum pump correctly. Each pump has a certain working pressure range, such as: diffusion pump is 10-3-10-7 mmHg. Within such a wide pressure range, the pump speed varies with the pressure, and its stable working pressure range is 5 x 10. - 4 5 x 10-6 mmHg. Therefore, the working point of the pump should be selected within this range, and should not work for a long time at 10-8 mmHg. Another example is that the titanium sublimation pump can work under 10-2 mmHg, but its working pressure should be less than 1 *10-5 mmHg.
3. Vacuum pumps should be able to remove all gases produced in the process of vacuum equipment under their working pressure.
4. Correct combination of vacuum pumps. Because of the selective pumping of vacuum pumps, sometimes the pumps can not meet the pumping requirements, and need to combine multiple pumps to complement each other to meet the pumping requirements. For example, the titanium sublimation pump has a high pumping speed for hydrogen, but can not pump, and the triode sputtering ion pump (or bipolar asymmetric cathode sputtering ion pump) has a certain pumping speed for argon. When combined, the vacuum device will have better vacuum. In addition, some vacuum pumps can not work at atmospheric pressure, need pre-vacuum; some vacuum pumps outlet pressure is lower than atmospheric pressure, need the front pump, so need to pump together.
5. Oil contamination requirements of vacuum equipment. If oil-free equipment is strictly required, various oil-free pumps should be selected, such as water ring pump, molecular sieve adsorption pump, sputtering ion pump, cryopump, etc. If the requirements are not strict, you can choose to have an oil pump, plus some oil pollution measures, such as adding cold traps, baffles, oil traps, etc., can also meet the requirements of clean vacuum.
6. Understand the composition of the gas to be pumped. The gas contains no condensable vapor, no particulate dust and no corrosiveness. When choosing a vacuum pump, you need to know the gas composition and choose the right pump for pumping the gas. If the gas contains steam, particulate matter and corrosive gas, consider installing condensator, dust collector and other auxiliary equipment on the inlet pipe of the pump.
7. How does the oil vapor of vacuum pump affect the environment? If pollution is not allowed in the environment, you can choose an oil-free vacuum pump or discharge oil vapor outside.
8. The vibration vacuum pump produced at that time has no effect on the process and environment. If the process is not allowed, please choose non-vibration pump or take anti-vibration measures.
9. Price, operation and maintenance cost of imported vacuum pumps.