1, vacuum pump working pressure vacuum equipment should meet the limits of vacuum and pressure of work demands. Such as: vacuum coating required 1 × 10-5mmHg vacuum, the vacuum pump of choice for at least 5 × 10-6mmHg. Is usually higher than the vacuum pump vacuum equipment vacuum half to one order of magnitude.
2, the correct choice of pump operating point. Each pump has a certain amount of working pressure range, such as: diffusion pump of 10-3 ~ 10-7mmHg, in such a wide range of pressure, the pump's pumping speed with the pressure change, its stable working pressure range of 5 × 10 -4 ~ 5 × 10-6mmHg. Thus, the pump operating point should be chosen within this range, but not under it in the 10-8mmHg long-term work. Another example is titanium sublimation pumps can work under 10-2mmHg, but the working pressure should be less than 1 × 10-5mmHg to be good.
3, vacuum pump, under pressure in their work should be able to discharge process vacuum equipment in all the gases produced.
4, correct combination of vacuum pumps. As the vacuum of selective extraction, thus, sometimes use a pump can not meet the exhaust requirements, the need of several pumps combined to complement each other in order to meet the exhaust requirements. Such as titanium sublimation pumps have a high hydrogen pumping speed, but can not pump helium, and the three pole-type sputter ion pump, (or two pole-type non-symmetric cathode sputtering ion pump) on the argon have a certain pumping speed, both of together will reduce the vacuum device to be a better vacuum. In addition, some pumps can not work under atmospheric pressure, to be pre-vacuum; some export pump pressure below atmospheric pressure, need to pre-stage pump, ancient capital of the need to combine the use of pumps.
5, vacuum equipment to oil pollution requirements. If the equipment demanding oil-free, they should select a variety of non-oil pump, such as: water ring pumps, molecular sieve adsorption pump, sputter ion pumps, cryogenic pumps. If the requirement is not strict, you can choose a pump, coupled with a number of oil pollution prevention measures, such as the Canadian cold trap, barrier boards, blocked oil wells, will also be able to achieve clean vacuum requirements.
6, understanding has been pumping gas composition, gas condensate vapor containing non-can, with or without particles of dust, with or without corrosive and so on. Select vacuum pump, you need to know the gas composition, select the appropriate response has been pumping gas pump. If the gas contains steam, particles and corrosive gases should be considered in the pump inlet pipe on the road to install auxiliary equipment, such as condensers, filter and so on.
7, vacuum pump oil vapor discharged from the environmental impact of how the. If the environment does not allow any contamination can choose oil-free vacuum pump, or the oil vapor outside.
8, vacuum pump vibration generated when the work process, and whether the impact of the environment. If the process does not permit the pump should be selected without vibration or take anti-vibration measures.
9, vacuum pump prices, operation and maintenance costs.