Liquid ring

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 Figure 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 of the pump. You can see this more clearly in Figure 2.

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

The pump requires a liquid (also called the sealant) to create vacuum the following. Prior to starting the pump, it must be partially filled up with the liquid sealant. The liquid could be water (making it a water band pump), essential oil or a solvent, dependant on the gear motor for greenhouse application.