A liquid band vacuum pump comes with an impeller with blades attached to a center hub situated in a cylindrical body but Water-lubricated Air Compressors off-set from the guts.
In Number 1 to the proper, you can observe the blades close to the the surface of the pump are closer to the outside wall than at the sides and bottom level of the pump. You can observe this more obviously in Figure 2.
The impeller sits among two end plates (port plates) that have shaped holes cut into them called ports.
The pump takes a liquid (also known as the sealant) to create vacuum the following. Before you start the pump, it should be partially filled with the liquid sealant. The liquid could be water (making it a water ring pump), essential oil or a solvent, depending upon the application.