Primary Air Fan get Vibration

Primary Air Fan is centrifugal type as usually get vibration at axial side. If vibration happen on radial side perhaps got misalignment between fan as driven and motor as drive.

But if vibration happen on axial side, perhaps misalignment or something else.



Misalignment coupling under torque can transmits axial force and vibration to the fan and motor due to frictional resistance and axial motion.


Rigid Coupling.
It used for shafts having good collinear alignment and must be installed with care and forethought. Connecting misaligned shaft with a rigid coupling can lead to bearing failure, fatigue shaft wore flange or broken flange bolt.

When used on line shafting, support bearing should be locate near the coupling and checked for both static and dynamic balance. although simple design, rigid coupling are generally restricted to relatively low speed application where good shaft aliment or shaft flexibility can be expected.


Vibration & Balancing
Heavy rotors high peripheral speeds require static and dynamic balancing. The level of balance should be so that the fan will run the "good" to "satisfactory" range at operating speed in accordance with the vibration chart.

Causes of vibration and suggested remedies are given below.



If excessive vibration occur, open the outlet damper then open and close the inlet damper. When fully closed, the fan is unable to discharge air and turbulence (vibration) can occur. Adjust the control as necessary.

If vibration continue, shutdown the fan, turn off the power supply and open the housing and inlet box access doors and inspect the rotor. Many causes of vibration as follow
1. Dirty on rotor make rotor damage.
2. Rubbing parts between rotor and housing.
3. Loosened parts.
4. Foundation support structure.

If vibration still continue
1. Check the coupling gap/spacer.
2. Check the bearing.



Believe it or not with add the fix coupling spacer/gap can reduce axial vibration.