Liquid Ring Vacuum Pumps

Liquid Ring Vacuum Pumps

Liquid ring vacuum pumps are used for operating vacuum levels up to 33-44 mbara, depending on liquid ring temperature. Moreover, it is fairly cheap. They provide high reliability because of their simplicity.

These types of pumps are normally used to handle gas mixtures which contain condensable vapors.

When the vacuum pump impeller rotates, the centrifugal force creates a liquid ring concentric to the periphery of the protective cover which facilitates the compression.

The eccentric assembly of the impeller with respect to the cover leads to an increased gap between the blades of the impeller at the inlet of the system and a small space to the outlet. When the gas comes in, is enclosed between the impeller blades and the liquid ring. When the impeller rotates, the liquid ring within the vacuum pump compresses the gas and pumps it out of the ring.

The liquid ring not only acts as a seal, it also absorbs the heat of compression, friction and condensation. In principle, any liquid can be used but water, oil, glycol or other liquids that will not vaporize at process conditions are most commonly used.

The main advantages of liquid ring vacuum pumps are the following:

  • Simpler design than the most other vacuum pumps, only use a rotation system.
  • May be made of any casting metal.
  • Small noise and vibration.
  • Very little increase in the discharge gas temperature.
  • Can handle condensable.
  • Suction capacities from 20 to 54, 000 m3/hr
  • Operating pressure down to 33 mbara
  • Wet and dry gases
  • High tolerance to liquid carry over
  • Low water usage
  • Low noise levels


  • Condenser evacuation
  • Pulp and Paper
  • Filtration
  • Chemical and Petrochemical applications
  • Power
  • Vacuum forming
  • Pharmaceutical
  • Mining
  • Steel degassing
  • Bio fuels

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