Liquid Ring Vacuum Pump

one stage: They operate in the vacuum range of 0 - 29"Hg. Capacity range 6 - 39000 CFM.

Two stages: They are more efficient in a higher vacuum range, in between 25 - 29"Hg. Available in a capacity range between 15 and 2800 CFM.

Low maintenance, because there is no metal to metal contact, between rotor and body.
Without internal bearings.