The sizing problem of vacuum pumps?
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Dear experts, given that I already know the required gas flow rate and the main pump, how do I select the gas flow rate for the secondary pump and the foreline pump?
I believe this issue can be left to the vacuum pump supplier.
Let me give an example: for Roots screw vacuum units, once we know the Roots pumping speed, we can select the appropriate foreline screw pump. The working pressure is 500 Pa. The Roots pump has a pumping speed of 300 L/S. For the screw pumps, models with pumping speeds of 50 L/S, 70 L/S, 110 L/S, and 150 L/S are all suitable. The minimum pumping speed configured for the screw pump is 30 L/S; therefore, these configurations are related to the operating pressure, the maximum pressure difference of the Roots pump, and the compression ratio between the two pumps.
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Depending on the compression ratio, we have many options regarding the pressure difference. If, in the end, a 150-sized screw pump is chosen, what is the basis for selecting a 150-sized screw pump? ? ?