Free Engineering Tool
Vibration Severity Chart — Legacy ISO 10816-1
Legacy ISO 10816-1 Class I–IV reference chart. Enter broadband RMS vibration velocity and the matching machine class to view zones A–D.
For current machine assessment, use the applicable machine-specific ISO 20816 part and manufacturer limits. This legacy chart alone does not establish acceptance criteria.
Evaluation
| Velocity (mm/s RMS) |
Class I ≤15 kW |
Class II 15–75 kW |
Class III >300 kW rigid |
Class IV >300 kW flex |
|---|
Legacy ISO 10816-1 Reference
This chart displays historical Class I–IV zones for broadband RMS vibration velocity measured on non-rotating machine parts. ISO 10816-1 was replaced by ISO 20816-1; the legacy values shown here are not universal ISO 20816 acceptance limits. The four zones describe:
- Zone A — Vibration of newly commissioned or reconditioned machines
- Zone B — Acceptable for unrestricted long-term operation
- Zone C — Not suitable for long-term continuous operation; remedial action required
- Zone D — Dangerous vibration levels; damage could occur; immediate action needed
Machine Classes
| Class | Description | Examples |
|---|---|---|
| I | Small machines ≤15 kW | Small pumps, fans, electric motors |
| II | Medium machines 15–75 kW (or ≤300 kW on special foundations) | Medium motors, pumps, generators |
| III | Large machines >300 kW on rigid/heavy foundations | Large motors, centrifugal compressors |
| IV | Large machines >300 kW on flexible/lightweight foundations | Turbogenerators, gas turbines, large fans |
Zone Boundary Values (mm/s RMS)
| Boundary | Class I | Class II | Class III | Class IV |
|---|---|---|---|---|
| A/B | 0.71 | 1.12 | 1.80 | 2.80 |
| B/C | 1.80 | 2.80 | 4.50 | 7.10 |
| C/D | 4.50 | 7.10 | 11.2 | 18.0 |
ℹ️ Note: These class-based values are a legacy ISO 10816-1 Annex B reference, formerly associated with ISO 2372. Machine-specific standards use their own groups, support conditions and limits. ISO 20816-1 provides the general framework; check the applicable part and manufacturer requirements before evaluating a machine.
⚠️ Important: Velocity is measured as broadband RMS in the 10–1000 Hz range. Peak velocity or narrowband readings should not be directly compared with these limits.
ISO 20816-1 replaced ISO 10816-1 as the general framework. Machine-specific parts define their own assessment criteria. Do not substitute this legacy Class I–IV chart for the current part and limits applicable to your equipment.
For this legacy chart, use broadband RMS velocity in the 10–1000 Hz range. Do not compare peak velocity directly with these limits. A peak-to-RMS conversion is only valid when the waveform is known; dividing by √2 applies to a single sinusoid.
Do not choose a higher class because a machine is critical. Confirm the machine type, power and support characteristics, then use the applicable machine-specific standard and manufacturer limits. If the class is uncertain, this legacy chart cannot establish an acceptance limit.
This generic legacy chart does not establish acceptance limits for those machines. Use the applicable pump or reciprocating-machine standard and manufacturer requirements.
Use the frequency bandwidth required by the applicable standard and machine type. This legacy chart assumes broadband RMS velocity over 10–1000 Hz; readings made with a different bandwidth may not be comparable.
The procedures described on this page were developed and field-tested by the Vibromera team using the Balanset-1A, a portable dual-channel balancer and vibration analyzer for on-site rotor balancing.
Portable vibration measurement and rotor balancing. Measure vibration and verify corrections against the limits applicable to your machine.
Nikolai Shelkovenko
Nikolai Shelkovenko is a vibration analysis engineer and the founder and CEO of Vibromera. For more than 15 years he has balanced rotating equipment in the field rather than on a test bench: mulchers, industrial fans, crushers, centrifuges, shafts and spindles. That work is what the Balanset instruments grew out of — they were designed as a tool a specialist can carry to the machine and use alone, on site, not as laboratory equipment. Vibromera was founded in 2017 and has been based in Porto, Portugal, since 2023. Development, assembly and support of the Balanset line all happen here. The flagship instrument is the Balanset-1A, a portable analyser for single- and two-plane balancing and for vibration diagnostics. Nikolai is personally involved in customer support, in working through difficult balancing cases and in the development of the software. He works with customers worldwide, in any language.
