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Maybe you don't understand the reason why a screw pump is added to the vacuum pump. Today, I will lead you to discuss this problem.

It is a positive displacement booster pump, in the higher vacuum area has a relatively large pumping speed. The compensation is due to the low vacuum degree of the front stage pump and the low pumping rate in the high vacuum area. Because of the characteristics of its use, the extracted gas can not be directly discharged into the atmosphere, so it needs to be matched with the corresponding front stage pump. As for the matching of what form of the front stage pump to see the specific use in what process. If it is used in vacuum distillation or dehydration and other condensable gas process, the best choice of water ring pump, such a configuration to avoid condensable gas is pumped into other mechanical pumps, resulting in emulsification of lubrication.

In general, the compression ratio should be less than 4. That is to say, if the main pump is a 600 L / L pump and its pumping rate is 600L / L, then the pumping speed of the corresponding front stage pump should not be lower than 150L / s. if the compression ratio is large, the pump will be overloaded. There is also a case of multi-stage vacuum pump matching the front stage pump, because there is one or more pumps between the vacuum pump and the front stage pump, so the front stage pump can be appropriately selected smaller.

In another case, the front stage pump should be larger. If it is intermittent production, because the working area of the vacuum pump needs a certain degree of vacuum to start. Generally, it is necessary to pump the system pressure to - 0.093 or more. Therefore, if the pumping rate of the front stage pump is small, the whole working time will be prolonged.

In short, a screw pump on the vacuum pump can reduce emulsification problems, reduce overload, and prolong working time.