A chopper pump is a centrifugal pump, which is equipped with a cutting system to facilitate chopping/maceration of solids that are present in the pumped liquid. The main advantage of this type of pump is that it prevents clogging of the pump itself and of the adjacent piping, as all the solids and stringy materials are macerated by the chopping system. Chopper pumps are available in various configurations, including submersible and dry-installed design and they are equipped with an electric motor to run the impeller and to provide torque for the chopping system. Due to its unique solids handling capabilities, the chopper pump is often used for pumping sewage, sludge, manure, and other liquids that contain large or tough solids.

Working Principle

The chopper pump is operated by an electric motor, which is close-coupled to the pump shaft and turns the impeller and the hardened steel knife system. An open impeller design is used to successfully pass the macerated solids or thick slurry. A set of hardened steel cutters is installed externally to the pump suction in order to macerate all solids prior to entering the hydraulic parts of the pump. A chopper pump should not be confused with a grinder pump, which uses its impeller as part of the cutting mechanism. Grinder pumps are typically used for light weight sewage applications, whereas chopper pumps are used for tough solids handling applications. The chopping system consists of a set of rotating cutters that are keyed to the shaft and work in conjunction with the stationary cutters, which are bolted to the suction plate. A system of mechanical seals is used to prevent the pumped liquid from entering the motor. The pump can either be connected to a pipe, flexible hose or lowered down a guide rail so that the pump sits on a coupling foot (aka base elbow), thereby connecting it to the discharge pipe.

Applications

Examples of applications where chopper pumps are commonly applied include:
• Scum pumping at wastewater treatment plants
• Sewage wet wells and lift stations
• Sludge pumping at biogas facilities
• Pumping agricultural manure (dairy, hog and poultry)
• Septage receiving stations
• Waste processing at slaughterhouses, poultry abattoirs, fish processing plants, etc.
• Paper mills / pumping of pulp