TL;DR
Excessive vibration is most often loose foundation bolts or collapsed anti-vibration mounts. Torque the foundation bolts first, then check the mounts before suspecting the airend.
What you might see
- vibration felt through base or floor
- enclosure panels rattling
- vibration level above 5 mm/s RMS
- mounting bolts working loose repeatedly
Likely causes
Loose foundation or base mounting bolts allowing the frame to walk under torque reaction
Degraded or collapsed anti-vibration mounts no longer isolating the compressor from the structure
Airend rotor imbalance from contamination, rotor tip wear, or a prior impact event
VFD resonance speed causing structural amplification at a specific frequency
Required tools
- Torque wrench and socket set
- Vibration meter (mm/s RMS)
- Elektronikon controller (skip frequency programming)
- LOTO kit
- Replacement anti-vibration mounts (if degraded)
Safety first
- Lock out before working on mounts or foundation bolts.
- Do not operate the compressor with foundation bolts missing or loose.
Procedure
- 1
Lock out the compressor.
- 2
Torque all foundation bolts to the value specified on the Atlas Copco installation drawing.[1]
- 3
Inspect each anti-vibration mount. Look for cracking, oil saturation, or visible compression set. Replace mounts that are visibly degraded.[1]
- 4
Restart the compressor and measure vibration velocity (mm/s RMS) at the bearing housings with a vibration meter. Readings above 7 mm/s indicate an internal issue.
- 5
If vibration peaks at a specific VSD speed, program a skip frequency band in the Elektronikon to avoid that resonant speed range.
- 6
If vibration is high across all speeds, inspect the airend inlet filter for debris that may have been ingested and damaged the rotors.
- 7
Airend rotor imbalance requires a specialist airend overhaul. Contact Atlas Copco service if internal balance is suspected.
Sources
Atlas Copco GA VSD+ Air Compressor User Manual, Atlas Copco
Atlas Copco GA VSD+ IOM, installation torque specifications and vibration limits (general)
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