A liquid ring vacuum pump is easy to operate and is utilized in a number of applications Liquid-Ring Vacuum Pump across various industries. A liquid ring pump works with a sealant necessary in its operation. This liquid can be water, oil or any additional solvent which is definitely rotated by an impeller within the casing of the pump.
As the shaft turns, a liquid ring is established by the centrifugal force generated by the rotating impeller. This drive holds the liquid band against the inner wall of the pumping chamber. Since the impeller is situated eccentric to the pumping chamber, the depth of entry of the blades into the liquid ring reduces and boosts as the impeller rotates. This creates increasing cell quantity on the inlet port side, creating vacuum.
On the discharge port side, the impeller cell volume decreases as the blades move further in to the liquid band. This escalates the pressure until discharge takes place through the discharge interface.
A continuous flow of clean sealing liquid is supplied to the pump via the sealing-liquid inlet.
Regarding the two-stage liquid ring pump, the discharge from the 1st stage does not discharge to atmosphere. Rather, the 
1st stage discharges through the manifold resulting in the second stage along with through a discharge interface positioned in the intermediate plate between your first- and second-stage impellers.