A Guide to Split Case Centrifugal Pumps
Split case pumps are a type of centrifugal pump where the casing is divided into two distinct chambers, either horizontally or vertically. The pump casings seal off the internal components from the outside while maintaining fluid pressure and preventing leakage. Unlike end suction pumps, where the suction, discharge nozzle and casing are in one chamber, split case pumps come apart easily to allow access to their internal parts, which makes maintenance a breeze.
What is a split case pump?
A split case pump is a type of split case centrifugal pump whose casing is divided into two removable sections — either horizontally or vertically — around a double-suction impeller supported by bearings on both sides. This design, sometimes called a split casing pump, allows the internal components to be accessed and serviced without disturbing the piping, motor alignment, or suction/discharge connections.
Split-case pumps have an impeller with bearings on both sides. This means the impeller is firmly planted during excessive movement or vibration, which makes them more efficient than frame-mounted pumps. Considered to be the workhorses of industrial and municipal applications, split-case pumps are more expensive than end-suction or vertical inline pumps, and are generally not as flexible as vertical turbines. However, when you professionally install and operate a split-case pump, they are one of the most durable, efficient, and dependable pumps, providing decades of service.
Demand for split case pumps has remained steady as municipal water infrastructure ages and industrial facilities look for equipment that balances long service life with manageable maintenance costs. Within the broader split casing pump market, horizontal designs remain the more widely adopted option due to their higher efficiency, while vertical designs continue to serve a smaller, more specialized set of high-pressure, high-temperature applications.
Types of Split Case Pumps
Split case pumps can be vertical or horizontal, depending on how the casing is split into the two chambers relative to the impeller. The suction and discharge nozzles are on either side of the bottom half of the casing, while the impeller is located on a shaft between two bearings, offering support on either side.
Vertical Split Case Pumps
Vertical split case pumps have a minimal footprint compared to other pumps with similar capacities. However, they are not so popular as they tend to have lower efficiency. Vertical split cases are suitable for transporting high-pressure, high-temperature fluids, which means they’re commonly found in industries such as oil and gas, HVAC systems and municipal water systems, among others.
Horizontal Split Case Pumps
Horizontal split case pumps are most common as they provide higher efficiencies (above 90%), making them ideal for pumping low viscosity fluids like water at low to medium pressure. They are stable at varied speed and suction orientations, which means they are well suited to municipal pumping stations and cooling towers, where water is required at constant pressure and the pump needs to work for long periods at a time.
For applications requiring higher total head than a single stage can provide, a horizontal split case multistage pump uses multiple impellers arranged in series within the same split casing design. This preserves the easy-access maintenance benefits of a standard horizontal split case pump while delivering the additional pressure needed for demanding water transport or high-rise building applications.
Vertical vs. Horizontal Split Case Pumps: At a Glance
| Factor | Vertical Split Case Pump | Horizontal Split Case Pump |
|---|---|---|
| Footprint | Minimal, space-saving | Larger footprint |
| Typical Efficiency | Lower | Higher (above 90%) |
| Best Suited For | High-pressure, high-temperature fluids | Low-viscosity fluids like water at low-to-medium pressure |
| Common Industries | Oil and gas, HVAC, municipal water systems | Municipal pumping stations, cooling towers |
| Popularity | Less common | Most common configuration |
Benefits of Split Case Pumps
Compared to end-suction or vertical inline pumps, split case pumps carry a higher upfront cost and offer less flexibility than vertical turbines — but their reliability and performance give them a clear long-term edge. Their in-between-bearings design also means they can work for extended periods without needing regular maintenance.
With a double suction impeller that can suck fluid in from both sides of the impeller instead of just one side (single-suction), it dramatically reduces loads on the bearings, offering excellent NPSH values.
In practical terms, a higher NPSH (Net Positive Suction Head) value means the pump is less prone to cavitation — a common cause of premature wear — which is one of the key reasons split case pumps are known for their longevity.
Split-case pumps are a more balanced, durable, and reliable machine than other pumps. With robust bearings and the maintenance friendly design of their casing, they’re the choice of many municipalities and industrial facilities.
In summary, the core benefits of a split case pump include:
- Double-suction impeller design that reduces bearing load and improves NPSH performance
- Easy-access, maintenance-friendly casing that doesn’t require disturbing piping or alignment
- Long service life and high reliability under continuous operation
- Strong efficiency, particularly in horizontal configurations (above 90%)
Choosing a split-case pump
However, deciding on a split-case pump can be difficult.
A few key questions can help narrow down the right fit:
- Pressure and temperature — does the application involve high-pressure or high-temperature fluid, or standard low-to-medium pressure water?
- Stages — will a single stage provide enough head, or does the application call for a multi-stage design, including a horizontal split case multistage pump for higher head requirements?
- Orientation — does the facility have the floor space for a horizontal split case pump, or does a vertical split case pump’s smaller footprint better suit the layout?
- Duty cycle — is the pump expected to run continuously for long periods, as in municipal or cooling tower applications?
Do check out our range of horizontal split-case pumps online.
If you have any questions about split-case pumps and which one you should be using, give Vissers Sales Corp., a call on 1-800-367-4180 (toll-free). Our experts are on hand to help you choose, install, maintain, and monitor a variety of equipment. And to answer questions about things you’ve previously tried gone wrong.
