The function of vacuum pump is to remove gas molecules from the vacuum chamber, reduce the gas pressure in the vacuum chamber, and make it reach the required vacuum degree. Generally speaking, there is a large range from atmosphere to extremely high vacuum. So far, no vacuum system can cover this range.
Therefore, in order to meet the requirements of process index, working efficiency and equipment working life of different products, different vacuum system configuration needs to be selected for different vacuum sections.
For a reliable vacuum system, the main pump of the vacuum unit is a key problem, which should not only pursue a certain index, but also be considered comprehensively according to the service conditions
1、 The type of main vacuum pump is determined according to the limit pressure that the vacuum chamber needs to establish.
In general, the selection of the limit pressure of the main vacuum pump is half to an order of magnitude lower than that of the vacuum chamber.
2、 The main pump shall be selected according to the working pressure required by the vacuum chamber for process production.
When selecting the main pump in the selection of vacuum pump, the working process environment of the main vacuum pump should be selected correctly. Within its working pressure range, all gas produced in the process of vacuum chamber should be eliminated. Therefore, the working pressure in the vacuum chamber must be within the optimum pumping speed range of the main vacuum pump.
3、 The main pump is selected according to the volume of the vacuum chamber and the required pumping time.
In the selection of vacuum pump, the volume of vacuum chamber has an effect on the time when the system reaches the limit vacuum. When the pumping time is fixed, the larger the volume of the vacuum chamber is, the larger the pumping speed of the main pump is.
4、 Combine the vacuum pump correctly.
Because of the different performance of various vacuum pumps, sometimes choosing one pump can not meet the requirements of pumping. Several pumps need to be combined to supplement each other to meet the requirements of pumping.
5、 If no oil is strictly required for vacuum system, all kinds of oil pumps shall be selected as main pumps. If the requirements are not strict, oil pump can be selected, and then some anti oil pollution measures, such as adding cold trap, baffle plate, oil trap, etc., can also meet the requirements of clean vacuum.
6、 When selecting a vacuum pump, you should know the composition of the gas to be pumped, and select the corresponding vacuum pump for the composition of the gas to be pumped. If the gas contains corrosive gas, particle dust, etc., dry vacuum pump, corrosion-resistant vacuum pump, etc., or auxiliary equipment shall be installed on the air inlet pipe of the pump.
7、 The main pump shall be selected according to the economic indicators such as the initial investment and daily maintenance cost of the complete vacuum system.