As the trend toward submersible pumps continues to grow, are you still holding on to the belief that having the pump at floor level makes maintenance and repairs easier? It’s a common thought that seems to makes sense on the surface (no pun intended.) But, in reality, submersible pumps that are matched to your specific needs are superior to most other types of pumps. And, the right submersible pump can reduce your operating and maintenance costs, and increase your operating uptime.
If you’ve avoided submersible pumps in the past, or simply haven’t been properly introduced, keep reading to learn why you may need to move your pumping power below the floor.
Types of Pumps
There are four common types of pumps we’ll examine:
Vertical Shaft Pumps
This design has a motor that is mounted on a bearing frame that is attached to a shaft that extends down to the pumping elements. Common designs include Vertical Column Pumps, Vertical Cantilever Pumps, and Vertical Turbine Pumps. Vertical pumps are generally used for pumping clean or lightly contaminated liquids. These are becoming less common and usually only found in older plants.
Self-priming pumps are designed to lift water by creating a vacuum at the pump suction. These large, bulky, floor mounted pumps utilize a recirculation casing to create the needed suction vacuum. These can handle solids up to three inches. The pump needs to be primed initially and then, possibly, re-primed. Pump solids, cleaning solutions, and high temperature liquids can often interfere with the priming capability of a self-priming pump design.
Air Operated Diaphragm Pumps
Air operated diaphragm (AOD) or air operated double diaphragm (AODD) pumps shift compressed air back and forth between chambers to force liquid into the discharge pipe. These semi-displacement pump designs can pump higher pressures with lower flows and are useful for moving viscous fluids. There are limitations in size, amount of flow or gallons per minute, and ability to handl<s>e</s> abstract solids and abrasives.
Submersible pumps are hermetically sealed and include the driving motor and the pumping wet end elements all in a compact design. These pumps are submerged in the pumping liquid below the floor. They are designed to push fluid to the surface rather than pull like other pumps. There are varieties that can be matched and customized to handle almost any application.
Maintenance and Repair
As we mentioned above, you may have the perception that pumps above the floor are easier to maintain and repair. The truth is that the right submersible pump will actually reduce maintenance needs. A properly selected submersible pump will be able to handle municipal, commercial and industrial wastewater solids without the worry of having priming issues or clogging. This limits downtime and maintenance significantly, saving time and money.
Air operated diaphragm pumps generally require a high number of replacement parts. In addition, the check valves get plugged often, solids can build up on the pumping chamber diaphragms, and seals get worn quickly.
Self-priming pumps also clog often. So much so that Condor Snack Company in Denver had to open up their self-priming pump twice per shift to manually unclog it. They switched to a BJM high temperature/high endurance submersible shredder pump which all but eliminated the clogging. With that switch and updated piping, they only need to maintain the pump once a month.
When considering the cost of pumps, it’s helpful to figure the Total Cost of Ownership. This tells a more complete story of costs than just looking at the purchase price. So, while a submersible pump may have a higher initial cost, the maintenance and operating costs are vastly lower than other types of pumps.
When used in the wrong applications, self-priming and AODD pumps will cause maintenance and repair costs to increase dramatically. Also, the compressed air that AODD pumps use is inherently expensive. This causes AODD pumps to cost up to five times more to operate than a submersible pump over its service life.
If you choose the correct submersible pump, it’s by far the most efficient way to handle the sump application. Water pressure forces the liquid into the pump suction, so it doesn’t require extra pumping energy like a self-priming pump would require. There are different types of submersible pumps (including shredder pumps, hard metal agitator pumps, stainless steel pumps, high temperature pumps, and more) that are not available in self-priming or AODD pumps. These features allow you to customize a submersible pump for specific applications you may have that other pumps are not able to address.
Some self-priming pumps have non-clog designs to handle solids and abrasives. But, they may not be able to shred the solids for easier passage. With the type of fluid it pumps and the suction lift required, it may not be able to develop a prime every time the pump needs to start. Part of its priming features includes recirculation within the chamber to drive the self-prime, making it 10%-12% less efficient than submersible pumps in the same application.
Beyond the factors above, there are some secondary considerations that may be important to you. Available working space may be at a premium in your factory or plant. Having a ground-level pump takes up an area that could be better utilized. Or, there simply may not be space available to put a ground-level pump.
Noise caused by vibrations within the pump can be an issue. Depending on the environment and physical location of the pump, the loudness can be a strong consideration. With submersible pumps being submerged, both the liquid and the walls of the sump tend to soften the noise produced.
The key is making sure that you have the right pump for your application. That means working with a supplier that is experienced and knowledgeable. BJM Pumps has 35 years of expertise and partners with highly trained, qualified distributors who can diagnose your issue and design the right solution. We’ve worked with a wide variety of industries and applications to create systems to save you time, money and hassles. You’ll receive unparalleled service from specification through installation and continued support throughout the life of the pump. Contact us at 860-399-5937 for more information.