Task $2-($A$)-$ Vibration Case Study

Excessive vibration in a fan

Centrifugal fan on foundation used to force heated air over drying malt Specification:

$2\mathrm{.}5$ m dia impeller.

Spherical roller bearings.

Multiple v$-$belt drive.

Operation problems:

Pulsations, on closure of inlet vanes $($flow control device$).$

Excessive vibration levels in spite of careful impeller balancing.

Prominent second and third harmonics in the frequency spectrum.

When run down, irregular knocking noises produced.

Also damage to machine identified on inspection:

Failure of two $24$ mm bolts holding steel pedestal to concrete foundation block.

Partial disintegration of grouting between pedestal & foundation.

Some damage to shaft surfaces where bearings attached.