Vacuum pump selection
1. The working pressure of the vacuum pump should meet the ultimate vacuum and pressure requirements of the vacuum equipment. For example, a vacuum drying process requires 10mmHg of working vacuum. The ultimate vacuum of the vacuum pump selected is at least 2mmHg, preferably 1mmHg. The ultimate vacuum degree of the pump is usually higher than that of vacuum equipment.
2. Select the working point of vacuum pump correctly. Each pump has a certain working pressure range, such as: 2 bv series water ring vacuum pump working pressure range 760 MMHG ~ 25 MMHG (pabs), in such a wide pressure range, the pumping speed of the pump vary with the pressure change (details refer to the changes of the pump performance curve), its stable working pressure range is 760 ~ 60 MMHG. Therefore, the working point of the pump should be more suitable in this range, but not for long-term work under 25~30mmHg.
3. The vacuum pump should be able to discharge all the gas produced during the process of vacuum equipment at the pressure of its work.
4. Correctly assemble the vacuum pump. Since the vacuum pump has selective pumping, it is sometimes necessary to select a pump that can not meet the pumping requirement. Several pumps need to be combined to meet the exhaust requirements. Such as titanium sublimation pump for hydrogen has a high pumping speed, but it can't take helium, sputtering ion pump and three pole type, type (or two extremely asymmetric cathode sputtering ion pump) to the argon pumping speed to a certain extent, the two together, will make the vacuum unit get good vacuum degree. In addition, some vacuum pumps can not work at atmospheric pressure, need a pre-vacuum; Some vacuum pump outlet pressure is lower than atmospheric pressure, need the former stage pump, therefore need to combine the pump to use.
5. Requirements for oil pollution by vacuum equipment. If the equipment strictly requires no oil, we should choose various oil pumps, such as water ring pump, molecular sieve adsorption pump, sputtering ion pump, cryogenic pump, etc. If the requirement is not strict, can choose to have the oil pump, add some oil-proof pollution measure, if add cold trap, baffle board, oil trap to wait, also can achieve clean vacuum requirement.
6. Understand the composition of the extracted gas. The gas contains no condensable steam, particle dust, corrosion, etc. When choosing a vacuum pump, you need to know the composition of the gas and select the corresponding pump for the pumped gas. If the gas contains vapor, particles, and corrosive gases, it should be considered to install auxiliary equipment on the inlet pipe of the pump, such as condenser, dust collector, etc.
7. The effect of oil vapor from vacuum pump on the environment. If the environment is not allowed to be contaminated, you can choose an oil-free vacuum pump, or steam the oil to the outside.
8. The vibration produced during vacuum pump work has no effect on the process and environment. If the process is not allowed, the pump with no vibration should be selected or anti-vibration measures should be taken.
9. Cost, operation and maintenance of vacuum pump.