The water ring vacuum pump uses water as the medium to complete the energy conversion. Water is both the working fluid and the sealing fluid. During the working process of the water ring pump, the heat generated by the work will increase the working water temperature, and at the same time a part of the water and gas will be discharged together.

Therefore, it is necessary to continuously supply water to the pump to cool and replenish the water consumed in the pump, maintain the formation of a normal working water ring, and meet the working requirements of the pump. Since it is necessary to continuously replenish water, it should also be allowed to bring some water from the pumped gas. In fact, water ring vacuum pumps are also widely used to pump water containing gas.

Therefore, when the water ring vacuum pump is working, in addition to the water supply from the pump water supply pipeline, it is also possible to enter some water from the suction port. If the vacuum pump uses a separate water supply line outside the shaft seal, it is also possible that a small amount of water flows from the shaft seal. This is generally the case for water ring vacuum pumps used in paper mills. Water enters the pump from the pump water supply pipeline, air inlet and shaft seal. The water entering the pump from different ways can not be well used as supplementary water to meet the pump's working needs, and the water entering the pump due to abnormal working needs will have a negative impact on the performance of the pump.