Industrial Pump Comparison: Cantilever Vs. Submersible Vs. Extended Shaft

There’s no one size fits all pump – no one solution for every scenario. If you have a sump and need to pump abrasive slurry – that sounds like a job for a GPM-Eliminator™ pump. In highly corrosive and high temperature environments, you’ll see better and more longstanding results from an extended shaft pump. Review our industrial pump comparison below and learn a little bit about each pump along with tips to best spec your next project.

Cantilever Pumps

First, there were cantilever pumps. 30-40 years ago, most industrial sump pump scenarios included a cantilever pump. These pumps were designed to handle hot, corrosive or otherwise volatile liquid materials, and they certainly worked – but not as efficiently or as powerfully as a submersible pump does today.

A traditional cantilever pump has bearings placed near the sole plate. This placement is not ideal as it does little to decrease shaft deflection generated by the hydraulic load of the impeller - and can often lead to failure in several critical parts, including shafts, bearings and seals. Today’s modern GPM-Eliminator extended shaft pumps have corrected this challenge by instead placing bearings near the pump’s impeller.

Although cantilever pumps are still in use today, there are several challenges that can arise when any older pump fails completing repairs and sourcing parts becomes more difficult. If replacement parts are available, which isn’t always the case, acquiring them may be a challenge: they may be out of stock, required to be recast or they may take months to arrive from overseas. In applications that rely on 24/7/365 operations, a few months of downtime is unacceptable. When selecting any pump, it is critical to understand the aftermarket support and availability of spare parts because it will come in to play at some point down the road. Selecting a pump that has a greater MTBF and a readily available supply of spare parts, will help ensure your operation for the long haul.

Submersible Pumps

Next came submersible pumps, a superior solution to many industrial sump pumping challenges. With an overall smaller footprint along with the ability to be placed directly IN to the sump, submersible pumps solved a lot of the challenges commonly associated with cantilever pumps.

The GPM-Eliminator is the world’s toughest and most reliable submersible slurry pump, and it was built to handle the most abusive applications. From dirty water to 70% solids, these pumps are engineered to provide years of trouble-free service. The GPM-Eliminator boasts decades of long, hardworking service.

For decades, our pumps have proven submersible pumps to be an excellent solution for most industrial sump applications – although there are a few exceptions, including applications that require specific hydraulic performance with explosion-proof motors or applications with unique chemical requirements that call for pumps made with exotic materials.

Extended Shaft Pumps

When it comes time to replace an aging cantilever pump, switching to a submersible solution can be a smart choice – but it isn’t the only option. Depending on your application needs, we recommend also looking to an extended shaft pump.

Extended shaft pumps are a natural fit for cantilever pump replacement. GPM custom-engineers extended shaft solutions with GPM-Eliminator pumps, fitting each pump to the specific size required for the job. One of the biggest advantages of an extended shaft pump over a cantilever pump is superior, modern engineering.

GPM engineers designed the extended shaft line of pumps with bearings near the impeller for additional protection. This design places extra support near the bottom of the pump which allows for a reduction in the shaft OD that can be longer than a traditional cantilever pump shaft which also takes less energy to drive the pump. We also include a double mechanical seal and operate in a sealed barrier fluid chamber to protect critical parts from contamination.

Lastly, GPM’s extended shaft pump design incorporates an explosion-proof motor, allowing the model to be used in tough applications that require explosion-proof ratings.

The Right Pump for Any Job

All pump models have their merits – and with a full pump line-up including both submersible and extended shaft pumps, GPM is ready to deliver the right pump for any job. If you’re in the market to replace a cantilever pump and are searching for a non-submersible solution, we invite you to learn more in our GPM extended shaft fact sheet.

Download the Fact Sheet