A liquid ring vacuum pump is simple to operate and is used in several applications across various industries. A liquid band pump works with a sealant necessary in its procedure. This liquid could be water, essential oil or any other solvent which can be rotated by an impeller within the casing of the pump.
As the shaft turns, a liquid band is created by the centrifugal force produced by the rotating impeller. This pressure holds the liquid band against the inner wall structure 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 reduces and increases as the impeller rotates. This creates increasing cell quantity on the inlet interface side, creating vacuum.
On the Liquid-Ring Vacuum Pump 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 interface.
A continuing flow of clean sealing liquid comes to the pump via the sealing-liquid inlet.
Regarding the two-stage liquid band pump, the discharge from the first stage will not discharge to atmosphere. Rather, the initial stage discharges through the manifold resulting in the second stage in addition to through a discharge slot located in the intermediate plate between your first- and second-stage impellers.