Overhung pumps are one of the most widely used centrifugal pump designs, valued for their simplicity, ease of maintenance, versatility, and compact footprint. Common in sectors such as water treatment, chemical processing, and HVAC, overhung pumps deliver reliable performance across a wide range of fluid-handling applications.
Understanding their function and applications can aid in selecting the right pump for specific operational needs.
What Are Overhung Pumps?
Overhung pumps feature a cantilevered shaft design in which the impeller is mounted on the end of a shaft supported by bearings located only on one side, outside the pump casing. This configuration allows the impeller to “overhang” beyond the bearing support, resulting in a streamlined and accessible structure. Most overhung pumps are single-stage, making them ideal for medium-flow, medium-head applications.
Overhung Pumps Types & Classification
Overhung pumps are typically classified by coupling or mechanical design, and by orientation. These distinctions help specify the right pump for your application based on installation space, required maintenance, horsepower, and process demands.
Coupling or Mechanical Design
- Close-coupled pumps feature the impeller mounted directly on the motor shaft, eliminating the need for a coupling. This compact, cost-effective setup is ideal for systems under 30 horsepower where installation simplicity and low maintenance are key, commonly used in HVAC systems, light-duty industrial processes, or food and beverage handling.
- Frame-mounted pumps separate the pump and motor shafts, connecting them with a flexible coupling. This configuration offers robust support for larger systems with heavier-duty demands, allowing for stronger shafts and larger bearings. These are commonly used in industrial facilities requiring continuous-duty operation over 30 horsepower.
- Rigidly coupled pumps also separate the pump and motor but use a rigid coupling that requires precise shaft alignment. The motor’s bearings absorb all pump thrust loads, making this design suitable for high-torque applications in compact or alignment-sensitive environments.
By Orientation
- Horizontal overhung pumps have a shaft that runs parallel to the ground, usually mounted on a baseplate. They’re easier to access for maintenance and are widely used across chemical processing, HVAC, and water treatment
- Vertical overhung pumps, on the other hand, have a shaft perpendicular to the floor and are often used in installations where floor space is limited. They are commonly found in offshore platforms, boiler feed systems, and other applications requiring compact footprints or sump pumping capabilities.
Classifying Overhung Pumps Performance Standards
For oil and gas or other high-performance settings, API 610 offers further subtypes (OH1 through OH6), which define standardized configurations for overhung pumps used in those industries. Overhung pumps commonly meet industry standards such as API 610 for petroleum and petrochemical applications or ANSI B73.1 for chemical process applications.
It is important to note that overhung pumps can be susceptible to shaft deflection and increased radial loads, which may reduce bearing and seal life in high-flow or high-head applications. Illinois Process Equipment offers pumps that meet industry standards, such as quality pumps from Flowserve.
Advantages of Overhung Pumps
Overhung pumps are popular in many industries due to their simple yet highly effective design. Their advantages extend across maintenance, installation, and operational performance, offering a solid return on investment for light-duty and continuous-duty applications.
- Compact Design: With a smaller footprint, overhung pumps are ideal for installations where space is limited, such as skids, equipment rooms, or offshore platforms.
- Fewer Components: With only one mechanical seal and fewer internal parts, they are easier to service, reducing the potential for failure and simplifying inventory management.
- Ease of Maintenance: The external bearing arrangement allows technicians quick access to seals and impellers without dismantling the entire pump system, which minimizes downtime.
- Versatility: Overhung pumps can handle a wide range of fluids, viscosities, and operating conditions, making them suitable for water treatment, chemical processing, HVAC, and more.
- Cost Efficiency: Fewer components and simplified servicing lower overall lifecycle costs compared to more complex pump types.
- Mounting Flexibility: Overhung pumps can be configured for horizontal or vertical installation, making them adaptable to a variety of plant layouts and equipment configurations.
This combination of operational reliability, design flexibility, and ease of service makes overhung pumps a dependable solution across fluid-handling applications.
Applications Across Industries
Thanks to their adaptable design and reliable performance, overhung pumps are widely used in many industrial sectors. Their ability to handle a variety of fluids, pressures, and environmental conditions makes them a go-to solution in both light-duty and demanding applications.
- Water and Wastewater Treatment: Overhung pumps are used to transfer clear water, manage sludge, and precisely dose treatment chemicals. Their efficiency and ease of maintenance are ideal for municipal and industrial treatment systems.
- Chemical Processing: Built to withstand aggressive chemicals across a broad pH range, many overhung pumps conform to ANSI B73.1 standards, ensuring safe, reliable operation in demanding chemical applications.
- Food and Beverage: Sanitary-grade stainless steel models with clean-in-place (CIP) compatibility are commonly used to handle syrups, dairy products, and other consumables in hygienic processing environments.
- HVAC Systems: Overhung pumps provide dependable circulation of water and heat transfer fluids in commercial and industrial HVAC systems, helping to maintain energy efficiency and thermal comfort.
- Oil and Gas: Designed to handle high-temperature, volatile hydrocarbons, overhung pumps are frequently used in refineries and petrochemical operations where performance and durability are critical.
Their broad utility and performance flexibility make overhung pumps preferred for plant engineers and maintenance teams across sectors.
Overhung pumps are a vital component in fluid management systems across industries, offering a blend of simplicity, reliability, and performance. Their compact design, ease of maintenance, and adaptability to various configurations, such as close-coupled, frame-mounted, horizontal, and vertical, make them suitable for a wide range of pumping needs.
Whether you’re operating a chemical plant, water treatment facility, food processing line, or an HVAC system, understanding the structure and capabilities of overhung pumps can help ensure optimal system performance and longevity. For support in selecting and specifying the right overhung pump for your application, reach out to our team of pump experts.
Illinois Process Equipment provides complete support in pump selection, system design, and maintenance planning. We help clients achieve reliable, cost-effective fluid handling with pump systems built to perform. Contact us today to explore the right overhung pump solution for your operation.
