2. Choose the working point of vacuum pump correctly. Each pump has a certain range of working pressure, such as: diffusion pump is 10-3-10-7 mmHg, in such a wide range of pressure, pump speed varies with pressure, its stable working pressure range is 510-4-510-6 mmHg. Therefore, the working point of the pump should be selected in this range, and it can not be allowed to work for a long time under 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 110-5 mmHg.
3. Vacuum pump should be able to discharge all the gas produced in the process of vacuum equipment under its working pressure.
4. Correct combination of vacuum pumps. Because vacuum pumps have selective pumping, sometimes one pump can not meet the requirements of pumping. It needs several pumps to be combined to complement each other in order to meet the requirements of pumping. For example, the titanium sublimation pump has a high pumping speed for hydrogen, but it can not pump helium, while the tripolar sputtering ion pump (or the bipolar asymmetric cathode sputtering ion pump) has a certain pumping speed for argon. If the two pumps are combined, the vacuum device will get a better vacuum degree. 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 they need to be combined to use.
5. Requirements of vacuum equipment for oil pollution. If the equipment is strictly oil-free, all kinds of oil-free pumps should be selected, such as water ring pump, molecular sieve adsorption pump, sputtering ion pump, cryopump and so on. If the requirements are not strict, you can choose to have oil pumps, plus some anti-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 extracted gas. The gas contains no condensable vapor, particulate dust and corrosiveness. When choosing a vacuum pump, it is necessary to know the gas composition and select the appropriate pump for the pumped gas. If the gas contains vapor, particles, and corrosive gases, it should be considered to install auxiliary equipment such as condenser, dust collector in the intake pipeline of the pump.
7. How does the oil vapor discharged from the vacuum pump affect the environment? If the environment is not allowed to be polluted, oil-free vacuum pumps can be selected or oil vapor can be discharged outdoors.
8. Whether the vibration produced by the vacuum pump has an effect on the process and environment. If the process is not allowed, vibration-free pumps should be selected or anti-vibration measures should be taken.
9. Vacuum pump price, operation and maintenance costs.
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