Centrifugal Pump Troubleshooting Checklist

Troubleshooting Checklist for Centrifugal Pumps Trouble Failure to deliver liquid

Pump does not deliver rated capacity

Pump does not develop rated discharge pressure

Pump loses liquid after starting

Trouble Pump over-loads driver

Trouble Excessive Vibration

Stuffing boxes overheat

Bearings Overheat

Bearings wear rapidly

Trouble Reference: GPSA Engineering Databook, 13th Edition, SI units and various web sources Prepared by: Email:

Centrifugal Pumps Check Points 1. Wrong direction of rotation. 2. Pump not primed. 3. Suction line not filled with liquid. 4. Air or vapor pocket in suction line. 5. Inlet to suction pipe not sufficiently submerged. 6. Available NPSH not sufficient. 7. Pump not up to rated speed. 8. Total head required greater than head which pump is capable of delivering. 1. Wrong direction of rotation. 2. Suction line not filled with liquid. 3. Air or vapor pocket in suction line. 4. Air leaks in suction line or stuffing boxes. 5. Inlet to suction pipe not sufficiently submerged. 6. Available NPSH not sufficient. 7. Pump not up to rated speed. 8. Total head greater than head for which pump designed. 9. Foot valve too small. 10. Foot valve clogged with trash. 11. Viscosity of liquid greater than that for which pump designed. 12. Mechanical Problems: - wearing rings worn - Impeller damaged or worn out - Internal leakage resulting from defective or damaged gaskets 13. Discharge valve not fully opened. 1. Gas or vapor in liquid. 2. Pump not up to rated speed. 3. Viscosity of liquid greater than that for which pump designed. 4. Wrong direction of rotation. 5. Mechanical Problems: - wearing rings worn - Impeller damaged or worn out - Internal leakage resulting from defective or damaged gaskets 1. 2. 3. 4. 5. 6. 7. 8.

Suction line not filled with liquid. Air leaks in suction line or stuffing boxes. Gas or vapor in liquid. Air or vapor pocket in suction line. Inlet to suction pipe not sufficiently submerged. Available NPSH not sufficient. Liquid seal piping to lantern ring plugged. Lantern ring not properly located in stuffing box.

Check Points 1. Speed too high. 2. Developed head greater than rated head. 3. Excessive recirculation. 4. Either or both the specific gravity and viscosity of liquid different from that for which pump is rated. 5. Mechanical Problems: - Misalignment - Shaft bent - Rotating element dragging - Packing too tight

Check Points 1. Starved suction - Gas or vapor in liquid - Available NPSH not sufficient. - Inlet to suction pipe not sufficiently submerged. - Gas or vapor pockets in suction line 2. Misalignment 3. Worn or loose bearings 4. Rotor out of balance - Impeller plugged - Impeller damaged 5. Shaft bent. 6. Improper location of control valve in discharge line. 7. Foundation not rigid 1. 2. 3. 4. 5. 6. 7.

Packing too tight Packing not lubricated. Wrong grade of packing. Insufficient cooling water to jackets. Packing provided improperly Mechanical seal hydraulic balance improper Uneven torquing of gland nuts

1. Oil level too low. 2. Improper or poor grade of oil. 3. Dirt in bearings. 4. Dirt in oil. 5. Moisture contamination in oil. 6. Oil cooler clogged or scaled. 7. Failure of oiling system 8. Insufficient cooling water circulation. 9. Insufficient cooling air. 10. Bearings too tight. 11. Bearing over-lubrication (when grease lubricants are used) 12. Misalignment 1. 2. 3. 4. 5. 6. 7. 8. 9.

Misalignment Shaft bent. Vibration. Lack of lubrication. Bearings improperly installed. Dirt in bearings. Moisture contamination in oil. Excessive or insufficient cooling of bearings. Oil / lubricant viscosity not maintained as recommended.

Check Points

Ankur Srivastava Chemical Engineer [email protected]