A liquid band vacuum pump is simple to operate and can be used in a number of applications across various industries. A liquid ring pump works with a sealant necessary in its procedure. This liquid can be water, oil or any additional solvent which is rotated by an impeller within the casing of the pump.
As the shaft turns, a liquid ring is established by the centrifugal force produced by the rotating impeller. This power 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 access of the blades in to the liquid 
ring reduces and raises as the impeller rotates. This creates increasing cellular volume on the inlet slot side, creating vacuum.
On the discharge interface side, the impeller cell volume decreases as the blades move further in to the liquid ring. This increases the pressure until discharge takes place through the discharge port.
A continuous flow of new sealing liquid is supplied to the pump via the Liquid-Ring Vacuum Pump sealing-liquid inlet.
Regarding the two-stage liquid ring pump, the discharge from the 1st stage will not discharge to atmosphere. Rather, the first stage discharges through the manifold leading to the second stage and also through a discharge port situated in the intermediate plate between your first- and second-stage impellers.