Proper assembly of a centrifugal pump and motor ensures efficient operation, minimizes vibration, and extends equipment life. Below is a structured procedure for assembling and aligning a centrifugal pump with its motor.
Before assembly, verify:
✔ Pump & motor specifications match (power, speed, flange size).
✔ Shaft dimensions (diameter, keyway) are compatible.
✔ Foundation is level, rigid, and grouted (if required).
✔ Baseplate is clean and free of distortions.
Position the baseplate on a leveled foundation.
Place the pump on the baseplate and loosely bolt it.
Install the motor on the baseplate, ensuring proper spacing for the coupling.
Use shims under the motor feet for initial height adjustment.
Check coupling type (flexible, rigid, or spacer coupling).
Align shafts roughly using a straightedge and feeler gauge.
Install coupling halves on both pump and motor shafts.
Ensure proper keyway fit (no excessive play).
Tighten set screws or bolts evenly.
Use a dial indicator or laser alignment tool.
Check for:
Parallel (offset) misalignment (side-to-side, up-down).
Angular (gap) misalignment (face alignment).
Adjust motor position using shims and bolts.
Recheck alignment after tightening all bolts.
Connect suction & discharge piping (ensure no strain on pump casing).
Use expansion joints if thermal movement is expected.
Verify lubrication (bearings, coupling).
Check rotation direction (match arrow on pump casing).
| Parameter | Acceptable Tolerance |
|---|---|
| Parallel Offset | ≤ 0.05 mm (0.002 in) |
| Angular Gap | ≤ 0.02 mm/100 mm (0.001 in/ft) |
| Vibration | < 2.5 mm/s RMS |
| Issue | Possible Cause | Solution |
|---|---|---|
| High vibration | Misalignment, unbalance | Recheck alignment, balance impeller |
| Overheating motor | Overload, misalignment | Verify amps, realign |
| Coupling failure | Excessive misalignment | Replace coupling, realign |
| Bearing wear | Poor lubrication, misalignment | Relubricate, correct alignment |
✔ Run pump at no-load (check for unusual noise/vibration).
✔ Monitor motor amps (should be near FLA at BEP).
✔ Check for leaks (mechanical seal, gaskets).
✔ Re-tighten bolts after 24–48 hours (settling may occur).
Proper centrifugal pump and motor assembly requires:
✅ Precise alignment (dial indicator/laser preferred).
✅ Strain-free piping (avoid forced connections).
✅ Correct coupling installation (keyway fit, torque).
✅ Post-installation testing (vibration, amps, leaks).
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