Centrifugal fans are used in various ventilation units and air conditioners. Depending on the installation situation, previously unforeseeable speed ranges may result in increased vibration levels in the resonant range.
There are many reasons for this: a high residual imbalance (e.g. caused by transport and handling), changes in vibration behavior after installation in the customer’s unit, and dirt adhering to the impeller. If the fan is operated frequently at excessive vibration levels, the bearings can be damaged and premature failures occur.