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Pump Troubleshooting Guide: Typical Faults, Causes, and Remedies
D Series Horizontal Multistage Centrifugal Pump, Clean Water Type
This guide summarizes common pump faults, their likely causes, and practical corrective actions. It is intended to help operators and maintenance personnel quickly diagnose issues on site and restore stable pump operation.
1. Pump Does Not Prime; Pressure and Vacuum Gauge Needles Fluctuate
Possible causes:
- Insufficient priming water in the pump
- Air leakage in the pipeline or at gauge connections
Recommended solutions:
- Refill the pump with sufficient liquid until it is fully primed
- Tighten and seal all leaking joints or interfaces
2. Pump Does Not Prime but the Vacuum Gauge Shows High Vacuum
Possible causes:
- Foot valve not opened or already blocked
- Excessive resistance in the suction pipeline
- Suction lift too high
Recommended solutions:
- Inspect, correct or replace the foot valve
- Optimize or replace the suction pipeline to reduce resistance
- Lower the suction lift to within the pump’s allowable range
3. Pressure Gauge Shows Pressure but the Pump Still Delivers No Water
Possible causes:
- Discharge pipeline resistance too high
- Incorrect motor rotation direction
- Impeller passages blocked
- Insufficient pump speed
Recommended solutions:
- Inspect or shorten the discharge pipeline and remove restrictions
- Check and correct the motor rotation direction
- Remove the piping connections if necessary and clean the impeller
- Increase pump speed to the rated value
4. Pump Flow Rate Is Lower Than Design Value
Possible causes:
- Pump passages or pipelines blocked
- Excessive wear of wear rings or other hydraulic components
- Insufficient rotational speed
Recommended solutions:
- Clean the pump casing, impeller passages, and pipelines
- Replace worn wear rings or other damaged parts
- Increase pump shaft speed to the specified value
5. Pump Power Consumption Is Excessive
Possible causes:
- Packing gland tightened too much, causing packing overheating
- Impeller wear leading to hydraulic inefficiency
- Operating at excessive flow rate
Recommended solutions:
- Loosen the packing gland to an appropriate level
- Replace the worn impeller
- Increase discharge pipeline resistance or partially close the valve to reduce flow
6. Abnormal Internal Noise and Pump Fails to Deliver Water
Possible causes:
- Flow rate too high, causing excessive losses in the suction pipeline
- Air ingress at the suction side
- Pumped liquid temperature too high, reducing available NPSH
Recommended solutions:
- Increase resistance on the discharge side to reduce flow rate
- Inspect the suction pipeline for leaks and structural issues
- Check the foot valve, reduce suction lift, seal all air leakage points, and lower suction conditions if necessary
7. Pump Vibration
Possible causes:
- Misalignment between pump shaft and motor shaft
- Pump shaft bent or not installed in a straight line
Recommended solutions:
- Realign the pump and motor so that their shaft centerlines coincide
8. Bearing Overheating
Possible causes:
- Insufficient or missing lubrication oil
- Misalignment between pump and motor shafts
Recommended solutions:
- Add appropriate lubrication oil
- Align the shaft centerlines and inspect or clean the bearing housing
Conclusion
Understanding typical pump fault symptoms and their root causes allows operators to take timely corrective actions and prevent serious failures. Regular inspection, proper alignment, correct priming, and adequate lubrication are essential to maintaining reliable pump performance. For persistent issues, consult the pump manufacturer or a qualified service provider.