Contributor: Carver Pump
Sump systems, used in industrial, residential, and commercial applications, have different pumping requirements based on several variables. There are many styles of pumps that can be used in sump applications, but for this article, we will focus on vertical cantilever pumps.
What are vertical cantilever pumps?
Vertical cantilever pumps are centrifugal pumps designed in a way where the impeller is “cantilevered” from the motor and baseplate (a cantilevered structure is one that is anchored at only one end – think of a diving board at the edge of a swimming pool). In a cantilevered pump, only the impellers, bushings, and casing are submerged in the sump liquid; they have no submerged seals, bearings, or suction check valves. The overhung shaft is supported by heavy-duty bearings (located above the pumped liquid).
Questions to ask yourself before selecting a vertical cantilever pump for a sump application:
- What is the required flow rate?
- What is the required pump head (the height at which the pump needs to lift the fluid)?
- How much power is required to operate the pump?
- What are the temperature ranges of the media being handled by the pump?
- What is the size and depth of the sump?
- Will there be solids in the fluid?
- Will the pump be running in continuous operation or dry run events?
Materials of construction are another important aspect to consider when choosing a sump pump. Most vertical cantilever pumps are composed of cast iron, which dissipates heat to the surrounding fluid; but in cases where fluid is corrosive, a different material may need to be used to ensure reliable operation and longevity. One such case is when a vertical cantilever pump needed to be manufactured in Alloy 20 for a power generation application involving sulfuric acid (read that story here: https://www.carverpump.com/story/alloy-20-in-sulfuric-acid-applications/)
Maintenance is another factor to consider. While some argue that pulling a submersible pump for repair is easier than removing a vertical pump, there are some vertical cantilever designs that are engineered to make service more convenient for maintenance teams. For example, the Carver Pump G2C models have a heavy duty cast iron bearing frame / motor mounting brackets that support the bearings above the tank surface and machine fit between the pump and motor shaft to maintain bearing life. The grease-lubricated ball bearings are located above the tank top for easy maintenance, and there is an external adjusting wheel that allows precise in-place adjustment of the impeller-to-casing clearance, which optimizes hydraulic performance over the life of the pump. A generalized approach is if the pit depth less than 3ft, a cantilever design is more cost effective. However, once the pit depth reaches lengths greater than 3 feet), most true cantilever pumps may become uneconomical for general water applications due to the increases in shaft diameters required (bearing housings, shaft seals, etc). At this point, typically a vertical sump pump is chosen which allows for smaller diameter shafts due to the increased number of line shaft bearing supports such as the Carver G2S.
If you have any questions about how to select a sump pump, or if you need a pump made with an uncommon material, submit your questions using the comments section below.
About Carver Pump
Since we built our first pumps in 1938, Carver Pump has become recognized as one of the leading centrifugal pump companies, building pumps to the most demanding engineering specifications and military standards in the world. We were one of the first American pump companies to attain ISO 9001 certification – the most recognized standard for quality in the world. This certification is your assurance that our commitment to quality includes not only our hardware, but also superior customer service, leading-edge R&D, and continuous improvement in everything we do. So whether the job is refueling fighter jets on the deck of an aircraft carrier, supplying paint to an auto assembly line, or bringing water to the fountain in a city park, we put our reputation on the line everyday with every pump we build. Learn more at www.carverpump.com.