A liquid ring vacuum pump has an impeller with blades mounted on a center hub positioned in a cylindrical body but off-set from the center.

In Body 1 to the proper, you can view the blades near the top of the pump are closer to the outside wall than at the sides and bottom of the pump. You can observe this more clearly 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 called the sealant) to create vacuum as follows. Before you start the pump, it should be partially filled up with the liquid sealant. The liquid can be water (rendering it a water ring pump), oil or a solvent, Roots Vacuum Pump dependant on the application.