A liquid ring vacuum pump is easy to operate and is utilized in several 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 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 structure of the pumping chamber. Since the impeller is situated eccentric to the pumping chamber, the depth of 
access of the blades into the liquid ring reduces and improves as the impeller rotates. This creates increasing cellular 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 increases 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 band pump, the discharge from the 1st stage does not discharge to atmosphere. Rather, the 1st stage discharges through the manifold leading to the second stage in addition to through a discharge Liquid-Ring Vacuum Pump interface located in the intermediate plate between the first- and second-stage impellers.