Pumps appear in a wide range of applications — sometimes for hobby-related uses like garden irrigation, and other times in industrial processes such as oil transfer. The types of pumps used to move a fluid from one place to another vary depending on their purpose, and accordingly, the causes of failures differ as well. Questions like *“Why do hydraulic pumps fail?”*, *“Why do centrifugal pumps make noise?”*, or *“What causes a centrifugal pump malfunction?”* are commonly encountered.
Before diving into the causes of pump failures, it’s important to talk about one critical factor that affects both the likelihood of breakdowns and the overall lifespan of your pump: maintenance.
It’s a well-known fact that many businesses don’t perform regular maintenance until a malfunction occurs. However, what is often seen as an “expense” — routine maintenance — actually prevents many future breakdowns.
- In short, pump maintenance:
- Helps prevent potential malfunctions.
- Ensures more efficient operation.
- Prevents possible downtime caused by failures.
- Provides long-term savings with short maintenance intervals.
- Extends the pump’s lifespan and improves performance quality.
If maintenance is performed regularly according to the manufacturer’s recommendations, the pump will likely operate smoothly and rarely break down. But if a malfunction occurs despite regular maintenance, the following points should be checked.
Centrifugal Pump Failures
Pump malfunctions can be categorized in different ways — mechanical, fluid-related, or electrical. Mechanical failures generally occur in the pump’s stationary or moving components. They can result from external factors, material fatigue, or unresolved earlier issues.
Centrifugal pump failures may also stem from fluid-related problems such as:
- Air not being properly removed from the pump.
- Operating speed being too low.
- Incorrect performance selection or operational errors.
- Suction depth exceeding the pump’s design specifications.
- Clogged fan due to dirt or debris — often seen in new installations where pipes were not properly cleaned before connection.
- Incorrect fan installation.
- Incorrect pump installation, such as wrong rotation direction.
- Leaks, cracks, or damage caused by poor maintenance.
- Misalignment of the coupling.
- Clogged suction filters due to debris or residue (dirt trap blockage).
- Air leaks in the suction pipe (system-related issues).
In addition to fluid problems, insufficient flow rate (capacity) in centrifugal pumps can also lead to failure. Common reasons include:
- Air trapped in the suction section — the pump must be filled with water to release trapped air.
- Excessive suction height — the pump may need to be placed lower.
- Leaks in the suction circuit or stuffing box.
- Air leakage through worn packing (gland).
- Partially closed or damaged suction/discharge valves (e.g., a damaged impeller).
- Clogged or incorrectly mounted impeller.
- Cavitation (excessive suction difficulty).
- Insufficient clearance for the suction strainer — dirt traps should not be too close to the pump flange.
Insufficient Pressure in Centrifugal Pumps
Pressure is the lifeline of a pump system. Inadequate pressure can cause several issues, such as:
- Low rotational speed (check RPM).
- Air or gas trapped in the liquid.
- Mechanical damage, such as a worn or reversed impeller.
- Incorrect rotation direction or cavitation.
- Faulty connections or fittings.
Noise and Vibration Issues
Just like in other machinery, excessive noise or vibration in pumps indicates possible failure. Common causes include:
- Unstable or misaligned base frame.
- Air trapped in the system or suction line.
- Insufficient or worn-out pump bearings.
- Impeller deformation, wear, or imbalance.
- Loose valves or protective components.
- Friction between rotating and stationary parts.
- Foreign objects causing imbalance — another reminder of the importance of regular cleaning and maintenance.
Electrical Failures in Centrifugal Pumps
Pump failures aren’t always mechanical or fluid-related — electrical issues are also common causes.
- The pump draws excessive power — rotational speed may be too high.
- Operating below rated pressure.
- Excessive discharge height or head pressure.
- Mechanical damage to the motor or pump (e.g., bent shaft, friction in rotating parts, or overtight packing).
- Incorrect or overly viscous lubricants.
- Low voltage or loose electrical connections.
If the Pump Stops After Running for a While
Sometimes, a pump may run normally but then stop unexpectedly or fail to deliver water. Possible reasons include:
- Air leakage in the suction section — inspect the packing and suction line.
- Insufficient water in the suction chamber — as the pump operates, the water level may drop, causing air intake. Always ensure there is enough water for continuous operation.