A liquid ring vacuum pump has an impeller with blades attached to a center hub located in a cylindrical body but off-set from the guts.

In Shape 1 to the proper, you can observe the blades close to the the surface of the pump are nearer to the outside wall than at the sides and bottom of the pump. You can view this more gear motor for greenhouse clearly in Figure 2.

The impeller sits among two end plates (port plates) that have shaped holes cut into them called ports.

The pump requires a liquid (also known as the sealant) to create vacuum the following. Prior to starting the pump, it must be partially filled up with the liquid sealant. The liquid can be water (making it a water band pump), oil or a solvent, dependant on the application.