Common problems with split case pumps and how to maintain them

Split case pumps are a commonly used type of centrifugal pump. They consist of a casing that is divided into two horizontal sections, allowing for easy access to the enclosed impeller and bearings for maintenance. While split case pumps are reliable, over time they can develop problems that can lead to reduced performance or failure. In this article, we will discuss several of the most common split case pump problems and detail troubleshooting procedures for identifying and resolving these problems.

• Impeller Wear

One of the most common issues with split case pumps is impeller wear. The rotating impeller pushes water through the pump using centrifugal force, providing the pumping action. Over time, grit, sediment, or corrosion can wear away the impeller's blades, reducing performance. Signs of excessive impeller wear include:
Decrease in pump output/capacity
Increased vibration and noise during operation
Increased operating temperatures
To troubleshoot, first visually confirm impeller wear during inspection. Check for thinning or jagged edges on the blades. If wear is severe, replace the impeller per the manufacturer's instructions. Also, inspect and clean the air intake screen to prevent further grit from being ingested.

Finally, if wear is rapid in your application, consider upgrading to a more durable impeller material. Regular maintenance inspections are also recommended to detect wear early.

• Suction Line Blockage

Pumping capacity depends heavily on having an unobstructed inlet line for water to flow smoothly into the pump suction. Over time, lines can accumulate debris, solid buildup or biological growth that restricts flow. Signs of trouble include:
Air bubbles in the water coming out of the pump
Repeated losses on down payments
Increased vibration and noise
Overheating despite good lubrication
To troubleshoot, first check the suction screen. Remove any debris or solids that are blocking water flow through the screen. Then, confirm that the pipe size on the suction side is adequate-any undersized line will restrict water flow. If the line size is adequate, check for closed valves, kinks, or collapsed inlet hoses that are blocking water flow.

In some cases, the pump casing itself can develop internal corrosion buildup or pitting from long-term exposure to chemicals. Again, this can lead to restricted flow and loss of main power. In these cases, disassembling the pump casing and physically cleaning or grinding the corroded surface may solve the problem. Alternatively, replacing a severely damaged pump casing can provide a long-term solution to the suction blockage problem.

Finally, regular intake pipe pigging and cleaning can remove buildup before blockage occurs and affects operation. Monitoring filter pressure drop can also provide advance notice of impending suction restriction.

• How to maintain:

(1) Drain the residual water in the water pump and pipeline.
(2) If it is easy to disassemble, you can remove the water pump and pipeline for cleaning.
(3) Check the ball bearing. If the inner and outer rings are worn, loose, the ball is worn or there are spots on the surface, it should be replaced. If it can be used, clean the bearing with gasoline or kerosene and apply butter for storage.
(4) Check whether the impeller has cracks or small holes, and whether the impeller fastening nut is loose. If damaged, it should be repaired or replaced. Check the clearance of the impeller anti-friction ring. If it exceeds the specified value, it should be repaired or replaced.
(5) When the water pump and pipeline are not disassembled, the outlet should be sealed with a cover to prevent debris from entering.
(6) When the drive belt is not in use, it should be removed, washed with warm water, wiped dry, and stored in a place without direct sunlight, and not in a place with oil, corrosion and smoke. Under no circumstances should the tape come into contact with oil, diesel or gasoline, and rosin and other sticky substances should not be applied to the tape. Before using the tape, remove the white powder on the contact surface of the tape.

(7) All screws and bolts should be cleaned with a wire brush and coated with engine oil or immersed in diesel for preservation.