Sliding-vane pump

A positive displacement pump in which an eccentric rotor revolves in an eccentric or circular case. See also external-vane pump. The pumping element consists of multiple blades which slide in slots in the rotor and divide the crescent-shaped fluid space into variable volumes. Some sources state that in the sliding-vane type, vanes do come into contact with the casing, whereas in "vane-type pumps" a clearance of about 0.004 inches is maintained between vanes and casing.