ISO 10816 Vibration Severity Zones (Superseded by ISO 20816-1:2016)
ISO 10816 — Mechanical vibration — Evaluation of machine vibration by measurements on non-rotating parts
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ISO 10816 is the international standard for evaluating the mechanical condition of rotating machinery from vibration measurements taken on the non-rotating parts — bearing housings, machine frames, and pedestals. Part 1 (ISO 10816-1:1995) establishes the general framework: broad-band RMS vibration velocity (mm/s) is measured and compared against class-specific zone boundaries (Zones A through D) to judge whether a machine is in new condition, acceptable for long-term operation, due for maintenance, or must be shut down immediately. Subsequent parts extend the classification to specific machine families (pumps, steam and gas turbines, wind turbines, and more); those machine-specific limits are not implemented in MechanixCalc.
The standard is the first check every condition-monitoring programme applies to rotating equipment. It does not itself set alarm or trip values: zone C means the machine is unsatisfactory for long-term continuous operation, and zone D that the severity is normally sufficient to cause damage — the actual alarm and trip settings are derived separately from a measured baseline for that machine. ISO 10816-1:1995 has been superseded by ISO 20816-1:2016. The MechanixCalc vibration tool uses the ISO 10816-1 Annex B (Table B.1) class ladder: enter the measured RMS velocity and select the machine class, and the calculator assigns the zone and converts velocity to peak displacement. Zone C and D are reported with the standard's own wording (unsatisfactory for long-term operation; severity normally sufficient to cause damage), not as alarm or trip settings. The same tool provides supporting vibration calculations — natural frequency, resonance, isolation design, DVA tuning, Campbell diagram, and shock response spectrum — all in a single PDF-reportable session.
Calculators that implement ISO 10816
What ISO 10816 covers
- ⚠️ SUPERSEDED: ISO 20816-1:2016 supersedes ISO 10816-1; machine-specific limits moved to ISO 20816 Parts 2–8, where values differ by part. The ISO 20816 series merges the non-rotating-part (10816) and rotating-shaft (7919) series. MechanixCalc uses the ISO 10816-1 Annex B (Table B.1) class ladder, which remains in wide industrial use — check which edition your specification calls up. Broad-band RMS vibration velocity (mm/s) is the primary measurement quantity on non-rotating parts
- Four machine classes by size and mounting — Class I (small, ≤15 kW), Class II (medium, 15–75 kW or up to 300 kW on rigid mounts), Class III (large, rigid foundations), Class IV (large, flexible or soft foundations)
- Four severity zones per class — Zone A (new-machine quality), Zone B (acceptable for unrestricted long-term operation), Zone C (unsatisfactory for long-term continuous operation — arrange correction), Zone D (severity normally sufficient to cause damage)
- Class-specific zone boundaries from 0.71 mm/s RMS (Class I, Zone A/B limit) up to 18.0 mm/s RMS (Class IV, Zone C/D limit)
- Conversion between broad-band RMS velocity and peak displacement at the rotational frequency for single-frequency estimates
- Parts 2 to 7 and 21 of ISO 10816, and now ISO 20816 Parts 2 to 8, extend the framework to specific machine families (steam turbines, industrial machines, hydraulic machines, reciprocating machines, pumps, wind turbines); MechanixCalc does not implement those part-specific limits
Parts of the standard
- ISO 10816-1General guidelines (non-rotating parts measurement framework, Classes I–IV, Zones A–D)
- ISO 10816-2Land-based steam turbines and generators over 50 MW
- ISO 10816-3Industrial machines with nominal power above 15 kW and nominal speeds 120–15 000 rpm
- ISO 10816-5Machine sets in hydraulic power generating and pumping plants
- ISO 10816-6Reciprocating machines with power ratings above 100 kW
- ISO 10816-7Rotodynamic pumps for industrial applications
- ISO 10816-21Horizontal axis wind turbines with gearbox
Governing formulas
v_RMS [mm/s] → Zone A / B / C / D (class-dependent boundaries)where v_RMS = broad-band RMS vibration velocity measured on a non-rotating part (mm/s). Zone boundaries by class — Class I: A/B = 0.71, B/C = 1.8, C/D = 4.5 mm/s; Class II: 1.12, 2.8, 7.1 mm/s; Class III: 1.8, 4.5, 11.2 mm/s; Class IV: 2.8, 7.1, 18.0 mm/s. Values from the ISO 10816-1:1995 Annex B (Table B.1) class ladder (the tool's basis; ISO 20816 Parts 2–8 use different values by machine type).
x_peak = v_RMS · √2 / (2π · f_rot) [mm]where x_peak = peak vibratory displacement at the rotational frequency (mm); v_RMS = measured RMS velocity (mm/s); f_rot = shaft rotational frequency (Hz). Note: this estimate assumes the vibration is dominated by the 1× component; multi-frequency broad-band measurements require spectrum analysis.
Frequently asked questions
What is ISO 10816 used for?
ISO 10816 is used to assess the mechanical condition of rotating machinery from vibration measurements taken on the non-rotating structure — bearing housings and machine frames. It compares the measured broad-band RMS velocity (mm/s) against class-specific thresholds to place the machine in one of four zones: Zone A (new-machine quality), Zone B (acceptable long-term), Zone C (unsatisfactory for long-term operation — arrange correction), or Zone D (severity normally sufficient to cause damage). The standard itself does not set alarm or trip values. It is the standard reference for condition monitoring and acceptance testing of rotating equipment worldwide.
What are the ISO 10816 machine classes and zone limits?
The ISO 10816-1 Annex B (Table B.1) ladder defines four classes by machine size and mounting: Class I covers small machines up to about 15 kW; Class II covers medium machines (typically 15–75 kW or up to 300 kW on rigid mounts); Class III covers large rigid-mounted machines; Class IV covers large flexibly mounted machines. The Zone A/B boundaries are 0.71, 1.12, 1.8, and 2.8 mm/s RMS for Classes I through IV respectively; Zone C/D danger limits are 4.5, 7.1, 11.2, and 18.0 mm/s RMS. Enter your measured velocity and class into the MechanixCalc vibration calculator to get the zone instantly.
Does ISO 10816 measure displacement, velocity, or acceleration?
ISO 10816-1 uses broad-band RMS vibration velocity (mm/s) as the primary measurement parameter, and the zone boundaries are defined in mm/s RMS. The MechanixCalc tool also converts velocity to a peak displacement estimate at the rotational frequency as a supporting figure.
How does ISO 10816 relate to ISO 20816?
ISO 20816 is the successor series to ISO 10816. ISO 20816-1 (2016) replaces ISO 10816-1 as the general framework document and introduces a consistent five-part structure across all machine families. ISO 20816-1:2016 supersedes ISO 10816-1 and the machine-specific limits moved to ISO 20816 Parts 2 to 8, where the values differ by part and machine type. ISO 20816 also merges non-rotating-part and shaft-relative vibration guidance. MechanixCalc uses the ISO 10816-1 Annex B (Table B.1) class ladder (Classes I–IV, Zones A–D), which remains a common reference in industry practice; it does not implement the ISO 20816 part-specific limits, so check which edition your specification calls up.
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