By Glenn Dorsch, P.E., and Kent Keeran, Vaughan Company Inc.
The chopper pump is a centrifugal pump that utilizes a chopping action between the impeller and suction plate. These pumps were originally designed in the 1960s for use in the local dairy industry to transport manure to and from storage tanks.
Since then this design has been continually refined to earn wide acceptance for many applications which require solids handling. These pumps are used in various phases of municipal and industrial sewage treatment, food processing, and pulp and paper, where the pumped liquid contains solids that need to pass through the pump without clogging or plugging.
The benefit of a pump with chopping action between the impeller and suction plate over a typical non-clog or slurry pump is that it reduces the solids size of material passing through the pump. The unique chopping requirements and suction arrangement of these pumps make it difficult to apply standard impeller design practices to achieve the desired hydraulic performance.
Past practices have approximated head and flow at best efficiency for new designs, but it has been difficult to predict head for other flow points, and almost impossible to predict pump efficiency. And as energy costs continue to rise, developing more efficient pumps becomes increasingly critical for all pump manufacturers.