Grinder Pumps, Cutter Pumps, and Chopper Pumps

Romtec Utilities routinely designs package lift stations for wastewater, stormwater, industrial processes, and clean water. Each of our pumping systems include pumps specific to the needs of the site and the project. But when it comes to pumps that macerate, there can be preferences as to what type of pumps to use. Essentially, there are three basic types of macerating pumps. Those are grinder pumps, cutter pumps, and chopper pumps, but there are other names out there such as slicer pumps. Let’s look at these pump technologies to see how each can benefit common lift station pumping applications.

“Grinder” is a term that is easily recognized in the pumping world. Installing a grinder pump lift station is a common solution for the residential market capable of dozens of homes. Grinder pumps can either be centrifugal or positive displacement, but submersible centrifugal grinder pumps are the most common in modern lift station design. Depending on the location and flow requirements, a grinder pump station might be the best choice for a residential wastewater project like a new development.

The grinder pump lift station is best applied to low flow and high head pumping applications. A submersible grinder pump grinds all the wastewater as it enters the pump into a slurry. The opening for these pumps is less than ½” in diameter. Because the opening is so small, the grinder pump must grind all the material into fine slurry containing no solids. This action allows the force main size to remain small without worry of blockages.

The major concern with grinder pumps is that if a solid too large for the pump intake gets into the system then it can cause problems for the pump. Grinder pumps cannot pass solids; they have to grind solids up in order to pump. Situations where medium and large solids get flushed or drained may require more robust pumps such as cutter pumps or chopper pumps.

A lot of people believe that cutter pump and chopper pump lift stations are the same as grinder pump lift stations. The confusion lies in the fact that they are all macerating pumps. Chopper pumps and cutter pumps can actually pass solids up to 3” in diameter; whereas, grinder pumps can only pass fine slurry. Typically, cutters and choppers are both types of submersible pumps. Any medium to large solids or stringy materials that are present in the wet well are cut down to a size the pump can handle.

Chopper pumps and cutter pumps can pump much larger ranges of flow than grinder pumps, making these lift stations suitable to more applications. Larger flow ranges also make cutter and chopper pump lift stations more efficient when used in the correct flow and head range. Because chopper pumps and cutter pumps don’t have to thoroughly pulverize solids, they typically require less maintenance and clog less frequently.

The term “grinder pump station” is well liked by the pumping world because the word “grind” seems to imply the complete breakdown of solids, but the truth is that grinder pumps have strict size limitations for solids-handling. When considering lift station design for wastewater or industrial process water with solids-handling requirements, Romtec Utilities will often let the pumping goals, duty points, and water conditions determine which type of macerating pumps should be used. In many applications, a solids-handling pump that does not macerate solids can function better and cost less.

Romtec Utilities designs lift stations with grinder pumps, cutter pumps, or chopper pumps to meet each customer’s wastewater lift station requirements. If customers or engineers prefer to use grinder pumps, we have no problem designing systems with grinders, but often times, there are other pump-types available that might be better suited to your specific project. If you have any questions, call the Romtec Utilities Sales Staff today and see if the grinder pump lift station is the best solution for your pumping problem. Check out our Technical Information video to learn more about the pumps we use.