A liquid ring vacuum pump has an impeller with blades mounted on a center hub situated in a greenhouse gearbox cylindrical body but off-set from the guts.
In Body 1 to the right, you can 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 see 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 takes a liquid (also called the sealant) to create vacuum the following. Prior to starting the pump, it should be partially filled up with the liquid sealant. The liquid can be water (rendering it a water band pump), essential oil or a solvent, dependant on the application.