The rotor of the fan has been corrected for static and dynamic balancing at the manufacturing plant, and should not be unbalanced under normal circumstances. However, one of the following factors can cause rotor imbalance:

1. Due to the manufacture of the balance process omission inspection, calibration is not accurate, balance in the de-weighting (or weighting) part of the inappropriate, the permissible value of the dynamic imbalance exceeds the prescribed value, the counterweight fast loose and so on. At this time, should check the balance block position or recalibration.
2. The rotor surface adheres to the spoils more (such as dust, grease, rust, etc.), which destroys the balance quality of the rotor. At this time, the rotor surface should be cleaned of spoils.
3. Due to manufacturing, transportation and storage of improper, caused by the shaft parts loose, impeller rivets loose, shaft disk and the shaft of the combined surface loose, spindle deformation, impeller deformation or loss. At this time, should identify the cause, tighten the loose outside, straighten the spindle, or trimming impeller.
4. The axial seal is not installed correctly, so that the shaft and sealing ring produce local friction, causing local overheating of the shaft, and the shaft is bent. At this time, the sealing ring should be checked in time, the gap between the upper and lower, straighten the shaft has been bent.
5. Sharp changes in the load of the gas transportation pipeline. At this time, the inlet and outlet valves of the fan and its piping should be checked for blockage of spoils and eliminated. If the eccentricity of the rotor is greater than the specified value, the centrifugal force generated when the rotor rotates will cause large vibrations. Vibration caused by rotor imbalance is manifested in the number of vibrations per unit of time is equal to the rotational speed, and the amplitude at different rotational speeds is proportional to the square of the rotational speed.

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