A liquid band vacuum pump is easy to operate and is utilized in a number of applications across various industries. A liquid band pump works together with a sealant required in its procedure. This liquid can be water, essential oil or any various other 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 generated by the rotating impeller. This drive holds the liquid ring against the inner wall structure of the pumping chamber. Since the impeller is located 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 interface side, creating vacuum.
On the Liquid-Ring Vacuum Pump discharge interface 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 slot.
A continuing flow of new sealing liquid comes to the pump via the sealing-liquid inlet.
Regarding the two-stage liquid band pump, the discharge from the initial stage will not discharge to atmosphere. Rather, the first stage discharges through the manifold resulting in the second stage and also through a discharge port positioned in the intermediate plate between your first- and second-stage impellers.