The working principle of the water ring vacuum pump is to take the air in the container away with the water as the working fluid, thus forming a certain vacuum. When the sealing performance of the container is not good and it is necessary to continue vacuuming, the small water injection valve can be used to reduce the vacuum or add the side of the road, so that the vacuum can be adjusted; if the sealing performance of the container is good, the required vacuum can be achieved. After the degree, drive again; When the water ring vacuum pump is working, the proper vacuum is required when the container is well sealed. The first method can be considered at this time. The degree of vacuum adjustment is usually designed by adding a return line between the intake line and the exhaust main line, and the controllability of the degree of vacuum is achieved by adding a regulating valve to the return line for flow adjustment. 1. Add a valve to the air inlet to adjust the switching amount of the valve, which can stabilize the equilibrium pressure of the system. 2. Add air bleed valve on the side of the intake pipe to adjust the air supply. 3. Control the water supply temperature of the water ring vacuum pump to adjust the ultimate pressure. 4. Control the water supply of the water ring vacuum pump to adjust the system balance pressure.