Patent ID: 8608445

Claim:
An impeller for use in a centrifugal pump, the pump including a pump casing having a chamber therein, an inlet for delivering material to be pumped to the chamber and an outlet for discharging material from the chamber, the impeller being mounted for rotation within the chamber when in use about a rotation axis, the impeller including a front shroud, a back shroud and a plurality of pumping vanes therebetween, each pumping vane having a leading edge in the region of an impeller inlet and a trailing edge, wherein the front shroud has an arcuate inner face in the region of the impeller inlet, the arcuate inner face having a radius of curvature (R s ) in the range from 0.05 to 0.16 of the outer diameter of the impeller (D 2 ), said back shroud including an inner main face and a nose having a curved profile with a nose apex in the region of the central axis which extends towards the front shroud, there being a curved transition region between the inner main face and the nose, wherein F r is the radius of curvature of the transition region, the ratio F r /D 2 being from 0.32 to 0.65.