Blade passing frequency
Blade passing frequency includes similar components such as vanes, lobes, and pistons.
The forcing frequencies are: Number of blades / Vanes / Lobes / Pistons x turning speed.
It is normal to see (Blade Pass Frequency) peak in the vibration spectrum of pumps, fans and compressors.
However, When the peak amplitude exceed the acceptable levels, this is due to a Blade Pass Frequency related fault.
Causes of high blade passing frequency are:
Rotor or housing eccentricityNon-uniform variable pitch bladesLoose, bent, or misaligned housing diffuser vanesBlade or vane wear (abrasion or cavitation)Operation (improper performance parameters - flow rate / pressures)Dirty, damaged or missing filtersInlet or discharge line restrictionsCavitation or any other operation related issue
By checking all the mentioned above, You can eleminate the root cause of the fault to increase equipment reliability.