Overall vibration severity limits are defined in ISO 10816-3 (for industrial machines above 15 kW) and the successor standard ISO 20816. For general industrial machines in the 600 to 3600 RPM range on rigid mountings, the zone boundaries from ISO 10816-3 are:
|
Zone |
Velocity RMS |
Assessment |
|---|---|---|
|
Zone A |
Up to 0.09 in/s (2.3 mm/s) RMS |
New machine; acceptable |
|
Zone B |
0.09 to 0.18 in/s (2.3 to 4.5 mm/s) RMS |
Acceptable for long-term operation |
|
Zone C |
0.18 to 0.28 in/s (4.5 to 7.1 mm/s) RMS |
Alarm — not suitable for long-term continuous operation |
|
Zone D |
Above 0.28 in/s (7.1 mm/s) RMS |
Danger — risk of damage |
Note
For machines on flexible mountings, zone boundaries are approximately double the rigid-mounting values. For acceleration measurements, a common starting point for general industrial machines is an alert at 0.5 to 1.0 g RMS and a danger alarm at 1.0 to 2.0 g RMS for the 10 to 1000 Hz range. These values should be tuned to the specific asset.
Spectral band alarms and feature-based alarms complement overall level alarms by detecting developing faults at specific frequencies before the overall level is significantly affected.
A baseline/deviation approach is strongly recommended as a complement to fixed absolute thresholds and in many cases provides earlier, more asset-specific warning of developing faults.
To establish a baseline:
-
After commissioning and verifying the machine is in a known healthy condition, collect representative data across at least several weeks of normal operation covering the full range of typical load and temperature conditions.
-
Configure baseline-referenced alarms in InsightCM on the alarm rule for any calculated feature or spectral band, triggering when the current value deviates from the stored baseline by a defined amount (for example, a 30% rise in a spectral band, or a 20% increase in overall velocity).
-
Review and update baselines after any maintenance event that changes the machine’s vibration characteristics (bearing replacement, realignment, balance correction, overhaul).
Note
A practical approach is to use fixed ISO-based absolute thresholds as the safety net and baseline-relative alarms as the early-warning layer.