A liquid ring vacuum pump comes with an impeller with blades mounted on a center hub located in a cylindrical body but off-set from the guts.
In Body 1 to the proper, you can see the blades near the the surface 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 known as the sealant) to create vacuum the following. Prior to starting the pump, it should be partially filled with the liquid Torque Arm sealant. The liquid could be water (rendering it a water ring pump), essential oil or a solvent, depending upon the application.