Patent ID: 6953321

Claim:
A centrifugal pump of the volute type comprising a pump casing with a suction side and a drive side, a circular portion extending between a cutwater region and a throat region, a discharge nozzle extending tangentially from the circular portion, and an impeller positioned within the pump casing and a drive shaft axially connected to the impeller for rotating the impeller within the pump casing about an axis, the pump casing having a contoured volute region formed along the outer periphery of the circular portion of the pump casing extending from the cutwater region to the throat region of the pump casing, the contour of the volute region, in axial cross section, being such that in a section of the circular portion extending from beyond said cutwater to said throat region the drive side of the casing is formed with two radii of curvature separated by a convex portion, the suction side of the casing is formed with a single radius of curvature and said outer periphery of said pump casing extending between said drive side and said suction side is curved relative to said axis and the curvature of said curved outer periphery changes about the arc of the circular portion extending from said cutwater region to said throat region.