Chapter Twelve - Liquid ring vacuum pumps and compressors with magnetic drive

Abstract

This chapter describes the liquid ring pumps belonging to the group of positive displacement pumps. The characteristic feature of this pump type is the energy transmission from the impeller to the fluid pumped by means of a liquid ring. In a liquid ring pump, the rotating impeller, which has straight or curved blades, rotates eccentrically in the pump casing, and transmits the energy to a liquid ring rotating concentrically in the casing. This arrangement causes a crescent-shaped space to form in the area bordering on the hub, with individual cells between the blades which are sealed by the liquid ring on the outside, and on the lateral cell walls (port plates) by narrow clearances sealed by a liquid film. The safety regulations that need to be followed include: avoidance of sources of ignition; limitation of the effects of an explosion on the casings; use of materials which do not react with the product pumped and prevent corrosion of pump components; leak tightness of casing partition lines and shaft seals of vacuum pumps, in particular, also in the reverse direction (from the outside to the inside).