Non-Clog vs Cutter. What’s The Difference?

Non-clog, semi-vortex impellers are a very good design choice for submersible sewage pumps. And for good reason: sewage contains solids, stringy material, and disposable waste that can clog submersible pumps. The semi-vortex design provides space between the pump inlet and the impeller for solids to pass through the volute and out the discharge without getting stuck in the impeller vanes.

If submersible sewage pumps with non-clog, semi-vortex impellers work so well, what do we need “cutter” pumps for? So happy you asked.


Non-Clog Is Not Truly Non-Clog

Non-clog submersible pumps are not truly capable of avoiding clogging. Every submersible pump has a throughlet or inlet, which is where liquid and solids enter the pump. If any solids larger than the diameter of the throughlet get sucked into the opening they will clog the pump. Stringy material is also famous for wrapping around semi-vortex impellers and jamming them. High quality pumps with thermal and/or amperage sensing protectors will automatically shut their motors off so they do not overheat. But nevertheless, this shuts the pump down which otherwise should be operating normally. Those of you who work in municipalities and hotel basements know what happens next…


Alarms, Shut Downs, and Maintenance

A clogged submersible sewage pump is a nightmare, to be kind. These pumps need to be raised out of their sump pits, unclogged, and then lowered back down to return to operation. As you may imagine, handling heavy submersible pumps caked with sewage is not enjoyable. Some sewage systems have control panels with reverse relays. These allow the operator to bump the pumps in reverse to try and dislodge any clogged or jammed debris. However, if the large debris is not removed from the sump pit it will eventually get sucked into the pump throughlet again. Either way, unclogging submersible sewage pumps and cleaning out sump pits is a messy, smelly, unpleasant operation that no one wants to deal with.


If It Doesn’t Fit…Cut It.

So what is the answer to this conundrum? Well, if it doesn’t fit in the throughlet, why not cut it so that it does? Enter the Cutter pump.

The Cutter pump is fitted with two unique parts:

  1. a cutter plate with serrated edges at the throughlet.
  2. a semi-open impeller with a tungsten carbide cutter tip braised onto the leading edge of the impeller vane.

As the impeller spins, the cutter tip slices large debris against the cutter plate like a pair of scissors. These smaller pieces can easily pass through the inlet and impeller and out of the discharge.


What Are The Advantages Of The Cutter?

Firstly, according to many sources in the wastewater management industry, there is a gigantic increase in “flushable” wipes and cleaning rags being flushed down the toilet. The COVID cleaning frenzy has certainly added to this phenomenon. The irony of flushable wipes and cleaning rags is that they are indeed flushable, but they are not necessarily “pumpable”. In other words, these wipes and rags have been causing a major catastrophe for non-clog, semi-vortex submersible sewage pump systems. Pumps operating in heavily used commercial environments are most susceptible to this problem.

The cutting mechanism on the Cutter pump slices flushable wipes and rags into smaller pieces, allowing them to pass through the pump and out of the sump pit into the main waste stream without clogging the system.

Another significant advantage to the Cutter pump is that it uses a semi-open impeller. Semi-open impellers move more liquid at the same head pressure than an equivalently sized pump with a semi-vortex impeller. Additionally, they consume less power. This means that the combination of a semi-open impeller and a cutting mechanism make the Cutter pump more efficient by reducing amp draw and decreasing operating costs.


So, Which Pump Is Best?

At the risk of sounding like everyone should get a trophy just for participating, the truth is that they both have their place. The real question is, which pump is best for your application? Cutter pumps are manufactured to target heavily-used commercial, industrial, and municipal sewage and wastewater applications where there is little control over what ends up in the system. The volume of solids and debris in these environments can be overwhelming for standard, non-clog semi-vortex submersible sewage pumps. For this reason, most Cutter pumps are designed with motors requiring three-phase power and a minimum of 230 volts or more to provide maximum efficiency and reduced electrical operating costs.

On the flip-side, for smaller operations with lighter incoming volume and better controls, non-clog semi-vortex submersible sewage pumps can be the perfect choice. In the event they do get clogged every now and then, these types of pumps can be easily removed from their sumps, cleaned, and returned to operation.

At the end of the day, sewage and wastewater management is a marathon, not a sprint. Therefore, you need to install pumps with decades of proven performance that will provide years of worry-free operation. And most importantly, you need to install pumps that meet your required specifications most accurately.

For more information on the Cutter pump, visit the CUTTER PUMP page.