Centrifugal Pump Hydraulics For Low Specific Speed Applications

Abstract

The hydraulic coverage in the low specific speed region has been ignored by most centrifugal pump manufacturers because of unfavorable hydraulic characteristics, and manufacturing obstacles such as small, difficult to cast hydraulic passages. A test program was developed to address the characteristics of curve shape, head coefficient, pump efficiency, and impeller axial thrust. A number of impeller and volute collector designs were tested in an attempt to optimize these performances characteristics. The combination of a high solidity, patent-pending impeller design and a constant velocity volute design provided low specific speed hydraulics with a constant rise-to-shutoff head characteristic, competitive pump efficiency, and low impeller axial thrust.