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 together with a sealant required in its procedure. This liquid could be water, essential oil or any additional solvent which is rotated by an Liquid-Ring Vacuum Pump 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 drive 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 into the liquid ring reduces and improves as the impeller rotates. This creates increasing cellular volume on the inlet interface side, creating vacuum.
On the discharge port side, the impeller cell volume decreases as the blades move further into the liquid band. This increases the pressure until discharge occurs 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 band pump, the discharge from the initial stage will not discharge to atmosphere. Instead, the initial 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.