Centrifugal Impeller Abnormal Vibration — Mass Imbalance or Bearing Damage

Question

Accepted Answer

Impeller vane corrosion or erosion causes mass imbalance — vibration >4 mm/s is dangerous. Check: Measure vibration (vertical, horizontal, axial) at bearing housing on-site — stop operation immediately if >4 mm/s. Check impeller for dirt/sludge deposits: normal at low speed but spikes at high speed (3,000~10,000 rpm) suspects deposits. Frequency analysis (FFT): large 1× = imbalance, large 2× = misalignment, high-frequency = bearing damage What to do: Visually inspect impeller for vane corrosion and erosion — if abnormal, remove impeller and perform dynamic balancing. If dirty, clean impeller then dynamic balance. If vibration doubles within one month, schedule immediate detailed inspection — impeller failure always occurs suddenly Coupling misalignment or rolling bearing wear. Check: Coupling alignment: measure both radial and axial with dial gauge — misalignment if >0.05 mm. Check bearing replacement interval — rolling bearing normal service life 20,000~30,000 hours What to do: Coupling misalignment: correct to radial ≤0.05 mm and axial ≤0.05 mm using shims or jack bolts. Bearing replacement: replace immediately when preventive replacement interval arrives or specific frequency vibration is confirmed. Run crankcase heater for 2+ hours before startup to prevent refrigerant liquid slug

Centrifugal Impeller Abnormal Vibration — Mass Imbalance or Bearing Damage

Likely causes

Impeller vane corrosion or erosion causes mass imbalance — vibration >4 mm/s is dangerous

Coupling misalignment or rolling bearing wear

Related cases