A liquid ring Liquid-Ring Vacuum Pump china vacuum pump is simple to operate and is utilized in a number of applications across various industries. A liquid ring pump works together with a sealant necessary in its operation. This liquid can be water, essential oil or any other solvent which is usually rotated by an impeller within the casing of the pump.
As the shaft turns, a liquid band is established by the centrifugal force generated by the rotating impeller. This push holds the liquid ring against the inner wall of the pumping chamber. Because the impeller is situated eccentric to the pumping chamber, the depth of access of the blades into the liquid ring decreases and raises as the impeller rotates. This creates increasing cell volume on the inlet interface side, creating vacuum.
On the discharge port side, the impeller cell volume decreases as the blades move further into the liquid ring. This escalates the pressure until discharge occurs through the discharge port.
A continuing flow of fresh sealing liquid comes to the pump via the sealing-liquid inlet.
Regarding the two-stage liquid ring pump, the discharge from the first stage will not discharge to atmosphere. Instead, the initial stage 
discharges through the manifold resulting in the second stage and also through a discharge port positioned in the intermediate plate between your first- and second-stage impellers.