A.Priming faulty
B.Suction head too high
C.Air in water
D.Discharge head too high
E.Mechanical defect
Mechanical sources of noise
Common mechanical sources of noise include vibrating pump components or surfaces because of pressure variations that are generated in the liquid or air. Impeller or seal rubs, defective or worn bearings, vibrating pipe walls, and unbalanced rotors are the examples of mechanical sources of noise in pumping systems.
Improper installation of couplings in centrifugal pumps often causes noise at twice pumping speed (Misalignment). If the pump speed is near or passes through lateral critical speed, noise can be generated by high vibrations resulting from imbalance or by rubbing of bearings, seals, or impellers. If rubbing occurs, it is characterized by a high-pitched squeal.
