Why choosing a split-case pump shouldn’t ever be a split decision

Love them or hate them, you can’t deny that horizontal split case (HSC) pumps are a wise choice for industries that need to move large quantities of fluid at different pressures. As we spoke about in previous article, the design of HSC pumps is what gives these unique pumps several advantages.

However, purchasing an HSC pump should never be a split decision. Weigh up the advantages and disadvantages beforehand with this handy guide.

Advantages of HSC pumps:

1. You’ll love HSC pumps because they’re so easy to inspect and maintain. Due to their split-casing, you can easily remove the upper half of the pump to inspect the rotor or other components. Because it’s so easy to access, you can diagnose any problem or issue with ease.
2. HSC pumps are smaller in size and allow greater efficiencies than similar frame-mounted pumps with the same rating. This means that HSC pumps can be installed in smaller areas, allowing you to maximize space and efficiencies.
3. The double-section impeller design of HSC pumps allows a lower net positive suction rate (HPSHR) and lower axial thrusts.
4. The between-the-bearings design of HSC pumps ensures bearings and components last longer under high-stress conditions and enable low deflection due to its short shaft. With separate chambers for fluids on each side of the impeller, heat can be more efficiently distributed as well.
5. The dual volute construction of most HSC pumps reduces radial thrust. This, combined with the dependability of HSC pumps means increased productivity and efficiencies.

Disadvantages of HSC pumps:

1. Horizontal Split case pumps typically require short shafts, which means that you need to connect them as close to the water source as possible. Moreover, by installing horizontal elbows on the suction side, this can create asymmetrical pressures that reduce bearing and seal life and make it harder for the pump to operate at its maximum efficiency.
2. The casing of HSC pumps do not allow confined gaskets, so this limits horsepower and pressure. As casing halves aren’t really separate, both the top and bottom halves will expand and contract differently, which can result in issues such as misalignment and/or wear on bearings and seals. This makes it crucial to find out the temperature, pressure, and other limitations from the manufacturer or by reading the OEM instructions, before making your decision.
3. HSC pumps have two stuffing boxes, which can raise costs as two seals or packings are required for each pump used. In addition, many HSC pump designs have stuffing box size restrictions that don’t allow for generic or less costly seals.
4. Pipe strain can be an issue for HSC pumps, but this varies according to the model and manufacturer.
5. While the double-suction impeller is an NPSHR advantage, the shaft running through the impeller decreases the eye. This can create issues with suction speed and even cause a departure from the best efficiency point (BEP). When operating away from the BEF, thrust issues can become a problem as well as damage on the impeller.

Any piece of equipment has its pros and cons. You need to decide if the advantages outweigh the disadvantages for your intended application before making a purchase.

Need any help making the decision on whether to use horizontal split-case centrifugal pumps? Make a considered decision by giving us 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.