Improvements relating to rotary pumps

970,820. Separating liquids from gases ; centrifugal separators. ROPER HYDRAULICS Inc. Dec. 7, 1962, No. 46365/62. Headings B1T and B2P. [Also in Division F1] A rotary pump for centrifugally separating two fluids of different densities comprises means defining a number of expansible and contractible pumping compartments, means for rotating the compartments, means for effecting relative movement of the inner and outer walls of the compartments away from each other adjacent the inlet 75 and towards each other as they move through a discharge zone, a first outlet port 81 communicating with the parts adjacent the inner wall of the compartments and a second outlet port 82<SP>1</SP> communicating with the outer parts of the compartments. As shown, the pump body 51 contains an eccentric ring 65 and a rotor 68 eccentrically disposed with respect to the inner periphery of the ring 65. Vanes 71 extend into a running seal with the inner surface of ring 65 forming between them pumping compartments. Fluid 79 from reservoir 78 consisting e.g. of air vapour and liquid is supplied to the compartments through inlet 75 and is rotated, the heavier liquid moving to a zone adjacent the outer periphery of the compartments. Separate outlet ports 81 and 82<SP>1</SP> are provided in the discharge zone of the pump, outlet 81 extracting the lighter air and vapour and outlet 82<SP>1</SP> removing the heavier liquid. Fluid leaving through outlet 81 is piped back to reservoir 78.