A liquid band vacuum pump comes with an impeller with blades mounted on a center hub positioned in a cylindrical body but off-set from the center.
In Determine 1 to the proper, you can timing pulley observe the blades close to the the surface of the pump are closer to the exterior wall than at the sides and bottom of the pump. You can observe this more obviously in Figure 2.
The impeller sits among two end plates (port plates) which have shaped holes cut into them called ports.
The pump requires a liquid (also known as the sealant) to create vacuum the following. Before you start the pump, it should be partially filled up with the liquid sealant. The liquid can be water (making it a water band pump), essential oil or a solvent, depending upon the application.