The working pressure of the selected vacuum pump should meet the vacuum limit and the working pressure requirements of the vacuum equipment; each pump has a certain working pressure range, and the working point of the pump should be selected to work within this range; check and determine the type and volume of the pumping required by the process. The characteristics of gas should be analyzed, such as corrosiveness, cohesion and so on. Because if the type of pumped gas reacts with the liquid in the pump, the pump system will be polluted. At the same time, it must be considered to determine the appropriate exhaust time and the gas footprint generated during the exhaust process.
Under its working pressure, the vacuum pump should be able to remove all the gas produced in the process of vacuum equipment, and determine the vacuum volume of the system. Check to determine the time required to achieve the required vacuum, the flow resistance and leakage of the vacuum pipeline. Considering that the required vacuum degree can be achieved and the required pumping rate can be maintained under certain technological conditions, the proper stage ratio between the main pump and the front pump can be determined by combining the vacuum pumps correctly, and the shorter and thicker pipelines should be used as far as possible in the design of the vacuum pipeline, and the general diameter of the pipeline is not less than the inlet of the vacuum pump.
In the design of vacuum system, the sealing property of the system should be improved and the leakage rate of the system should be reduced. The suitable sealing material should be selected. The actual volume flow of the gas pumped by the liquid ring vacuum pump is related to the working liquid. The higher the working liquid is, the higher the vapor partial pressure is, and the working liquid is vacuum-to-vacuum.
The poorer the condensation effect of the inlet steam of the pump is, the smaller the volume flow of the pumped gas of the vacuum pump is. It is suggested that the working fluid with lower saturated vapor pressure should be selected and the temperature of the working fluid should be controlled at the same time. For the gases with high solidification point, such as glycerol, octamethylcyclotetrasiloxane and hexamethyltrisiloxane, the temperature of the Roots pump should be increased in order to avoid such gases from condensation and deposition in the Roots pump, such as through heating. Nitrogen is used to increase pump temperature, and new technology is used in vacuum system design to achieve automatic control and interlocking protection.
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