As the name implies, oil-sealed liquid ring vacuum pumps require oil to create a seal inside the pump. The impeller is the only moving part. It rotates without contact within the pump casing. A rotating liquid ring seals the impeller on the front and seals its blades against one another. In order to keep the liquid ring stable, oil is also permanently sucked into the pump chamber and is discharged together with air.

The excentrical arrangement of the impeller in the casing creates variable compression chambers between the impeller blades during rotation, which causes the conveyed air to be compressed within a full revolution.

An oil ring is required to create a tight seal between the tip of the impeller blades and the pump housing.

A mixture of air and oil is discharged from the pump into the separator. There are four stages of oil and smoke removal to provide smoke-free exhaust.

The reclaimed oil is then cooled in an air-to-oil heat exchanger. The cooled oil is then used again to seal the pump.