The best working range of vacuum pump (PA): 105 ～ 10 105 ～ 102 102 ～ 11 ～ 10-1 5 × 10-2 ～ 10-4
1. The limiting pressure of vacuum pump should meet the working pressure of the process. Generally, the limit pressure of vacuum pump is about one order of magnitude lower than the process requirements.
2. Each kind of vacuum pump has a certain working pressure range, so the working point of the vacuum pump should be selected within this range, rather than allowing it to work under the allowable working pressure for a long time.
3. Under its working pressure, the vacuum pump shall be able to discharge all gas produced in the process of vacuum equipment.
4. Select vacuum unit:
① When a vacuum pump can not meet the requirements of pumping and vacuum, several vacuum pumps need to be combined to complement each other to meet the process requirements.
② Some vacuum pumps can’t work under atmospheric pressure and need pre vacuum; some vacuum pumps need pre pump because the outlet pressure is lower than atmospheric pressure. The combined vacuum pump, we call it vacuum pump unit, it can make the vacuum system get better vacuum degree and exhaust volume. We should choose the combined vacuum pump correctly, because different vacuum pumps have different requirements for the extracted gas. For example, in general, roots vacuum pump – rotary vane unit is not suitable for systems with more condensable gas.
5. When you choose oil seal pump, you should first understand whether your vacuum system has requirements for oil pollution. If the equipment is strictly oil-free, various oil-free vacuum pumps should be selected, such as: water ring vacuum pump, etc. If the requirements are not strict, oil pump can be selected, and some anti oil pollution measures, such as adding cold well, oil trap, baffle, etc., can also meet the requirements of clean vacuum.
6. Know the composition of the extracted gas, including no condensable steam, particle dust, corrosiveness, etc. When selecting 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 gas, auxiliary equipment, such as condenser, dust remover, etc., shall be installed on the air inlet pipeline of vacuum pump.
7. When choosing the oil seal vacuum pump, we should consider how the oil vapor (oil fume) discharged from the vacuum pump affects the environment. If the environment is not allowed to be polluted, the oil-free vacuum pump should be selected or the oil vapor should be discharged to the outdoor.
8. Whether the vibration produced during the operation of vacuum pump has any impact on the process and environment. If the process is not allowed, the pump without vibration shall be selected or anti vibration measures shall be taken.
9. Maintenance cost, price and operation of vacuum pump.
After we have considered all kinds of situations, we can finally determine a solution suitable for you:
(1) Minimum investment cost.
(2) Minimum production and operation cost.
(3) The first two cases can be reasonably and evenly distributed.