Dear Experts ,

did you ever balance oval or bend fans successfully on site with in the tolerance . i have faced difficulty to balance so many times after repairs done onsite due to bending of fans Base plate and shroud .

Yesterday i tried to balance a fan onsite and it did not respond well after i removes the fan pulley  belts and balanced statically .After the Vibration reduced from 55 mm/sec to 17 mm/sec .After the fan not respond for balance if additional weight added and vibration increasing .Actually it is a old fan and it has repaired onsite after hub cracks developed .

Need your feed back .

Original Post

Hi Kishore

No matter how much old or repaired the equipment is. If it has unbalance it can be cured.

What is an oval or bend fan? You said about bend in the base plate. surely it will contribute in vibrations. I would rather go for such corrections first & lastly balance it.



First off, always perform a running speed phase analysis plot. I prefer using a tach for absolute phase with a roving sensor but cross channel works as well. A balance issue needs to be confirmed first always. It will also let you know if you have a bent or cracked shaft, alignment issues etc... Also check all bolts for tightness, looseness of components, check for soft foot (and/or confirm base flatness) and do a proper alignment on components before you start balancing. If you are balancing a fan with springs/isolators on the base, sometimes it helps to drive wooden wedges between the base and the floor in order to take out the isolation. I have chased a few around in circles which were not effectively stiffened first. First and foremost ensure your issue is in fact balance by utilizing phase analysis.

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