A liquid ring vacuum pump comes with an impeller with blades mounted on a center hub situated in a Scroll Vacuum Pumps cylindrical body but off-set from the guts.
In Physique 1 to the right, you can observe the blades close to the top of the pump are closer to the exterior wall than at the sides and bottom level of the pump. You can observe this more clearly 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 as follows. Before you start the pump, it must be partially filled with the liquid sealant. The liquid could be water (rendering it a water ring pump), oil or a solvent, dependant on the application.