The role of the vacuum pump is to extract gas molecules from the vacuum chamber, reducing the gas pressure in the vacuum chamber, to achieve the required degree of vacuum. Broadly speaking, there is a wide range of atmospheres to very high vacuum, and so far no vacuum system has been able to cover this range. Therefore, in order to meet the technical requirements of different products, work efficiency and equipment working life requirements, different vacuum sections need to choose different vacuum system configurations. For optimum configuration, the following points should be considered when choosing a vacuum system: Determining the working vacuum range: First, you must check to determine the degree of vacuum required for each process. Because each process has its own range of vacuum degree of adaptation, we must carefully study to determine. Use of the vacuum pump Determine the ultimate vacuum Check the ultimate vacuum of the vacuum pump system based on the vacuum required for the process because the system ultimate vacuum determines the optimum working vacuum of the system. In general, the ultimate vacuum of the system is 20% lower than the working vacuum of the system and 50% lower than the ultimate vacuum of the foreline pump. The type of gas to be drawn and the amount of gas to be extracted Check the type of gas to be extracted and the amount of gas to be extracted as required by the process. This is because if the type of gas being pumped reacts with the liquid in the pump, the pump system will be contaminated. At the same time must consider determining the appropriate exhaust time and exhaust gas generated during the process. The vacuum volume check determines the time required to reach the required vacuum, the flow resistance and leakage of the vacuum tubing. Consider to achieve the requirements of the vacuum degree of vacuum in a certain process conditions required to maintain the vacuum pumping rate. S = 2.303V / tLog (P1 / P2) where: S is the pump suction rate (L / s) V is the volume of the vacuum chamber (L) t is the time required to reach the required degree of vacuum For the initial Torr P2 is the required Torr For example: V = 500L t = 30s P1 = 760Torr P2 = 50Torr Then: S = 2.303V / t Log P1 / P2 = 2.303x500 / 30xLog 760 / 50) = 35.4L / s Of course, the above formula is only theoretical results, there are a number of variables are not taken into account, such as pipeline flow resistance, leakage, flow resistance of the filter, was pumping gas temperature. In fact, the safety factor should also be taken into account.