A liquid band vacuum pump is simple to operate and is utilized in a number of applications across various industries. A liquid ring pump works with a sealant needed in its operation. This liquid can be water, essential oil or any other solvent which is definitely rotated by an Liquid-Ring Vacuum Pump impeller within the casing of the pump.
As the shaft turns, a liquid ring 
is created by the centrifugal force produced by the rotating impeller. This push holds the liquid band against the inner wall of the pumping chamber. Because the impeller is situated eccentric to the pumping chamber, the depth of entry of the blades in to the liquid ring decreases and increases as the impeller rotates. This creates increasing cell volume on the inlet slot side, creating vacuum.
On the discharge slot side, the impeller cell volume decreases as the blades move further into the liquid ring. This increases the pressure until discharge takes place through the discharge slot.
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 does not discharge to atmosphere. Rather, the initial stage discharges through the manifold resulting in the second stage in addition to through a discharge interface situated in the intermediate plate between the first- and second-stage impellers.