Liquid Ring Operating Principle


As the name implies, water-sealed liquid ring vacuum pumps require water 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, water 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.

A water ring is required to create a tight seal between the tip of the impeller blades and the pump housing. There are (3) different ways a liquid ring pump utilizes the sealing water.

  • “Once thru re-circulating” system: sealing water is introduced into the pump, discharged, and sent directly down the drain. This type of system is very simple in design but  does require large amounts of water to operate.
  • “Partial re-circulating” system: sealing water is introduced into the pump and discharged. Some of the discharged water is re-circulated and used again to seal the pump. This type of system is relatively simple in design and, since some of the water is re-used, it does not require as much water as the “once thru” to operate.
  • “Total re-circulating” system: The discharged water is cooled in a water-to-water heat exchanger utilizing chilled water as a cooling media. The cooled water is then used again to seal the pump. Only a small amount of fresh purge water is needed to prevent bacterial growth.

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