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ISO 10816 Vibration Severity Chart and Zone Limits

ISO 10816 classifies overall vibration velocity into four evaluation zones so a technician with a handheld meter can say whether a machine is healthy. This lookup puts the zone boundaries for the common machine classes in one searchable table.

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Standard part	Class or group	Typical machines	Support	A/B limit (mm/s RMS)	B/C limit (mm/s RMS)	C/D limit (mm/s RMS)
10816-1	Class I	Small machines up to about 15 kW	Any	0.71	1.8	4.5
10816-1	Class II	Medium machines 15 to 75 kW, or up to 300 kW on special foundations	Any	1.12	2.8	7.1
10816-1	Class III	Large machines on rigid, heavy foundations	Rigid	1.8	4.5	11.2
10816-1	Class IV	Large machines on relatively soft foundations, turbo sets	Flexible	2.8	7.1	18
10816-3	Group 1	Large machines, rated above 300 kW up to 50 MW	Rigid	2.3	4.5	7.1
10816-3	Group 1	Large machines, rated above 300 kW up to 50 MW	Flexible	3.5	7.1	11
10816-3	Group 2	Medium machines, 15 kW up to 300 kW	Rigid	1.4	2.8	4.5
10816-3	Group 2	Medium machines, 15 kW up to 300 kW	Flexible	2.3	4.5	7.1
Zone A	Zone A	Newly commissioned machines normally fall here	n/a	0	0	0
Zone B	Zone B	Acceptable for unrestricted long-term operation	n/a	0	0	0
Zone C	Zone C	Generally unsatisfactory for long-term operation, plan a repair	n/a	0	0	0
Zone D	Zone D	Severe enough to cause damage, act now	n/a	0	0	0

Values are overall broadband velocity in mm/s RMS, measured typically from 10 Hz to 1 kHz on bearing housings. Zone rows carry 0 in the limit columns because they only describe meaning. ISO 20816 has replaced ISO 10816 in newer editions, so confirm which edition your contract or procedure cites. Treat these as guidance, not a substitute for the machine builder limits.

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How to use the table

Find your machine by power rating and by how it is mounted, then compare your measured overall velocity in mm/s RMS to the A/B, B/C and C/D boundaries. Below A/B you are in zone A or B and can keep running. Between B/C and C/D you are in zone C and should plan a repair at the next convenient stop. Above C/D you are in zone D and the machine is at risk of damage. Use the search box to filter by class, group or support type, then export the filtered rows to Excel to paste into a route sheet or alarm configuration.

Measure on the bearing housing in the radial directions
Use RMS velocity, not peak or peak to peak
Decide rigid or flexible support before reading the row
Record the measurement point so trends stay comparable

What the standard actually measures

ISO 10816 evaluates broadband vibration velocity on non-rotating parts such as bearing housings. Part 1 gives the general class scheme, and part 3 covers industrial machines above 15 kW with a nominal speed between 120 and 15,000 rpm. The zones are a screening tool. They say how severe the overall level is, not what is wrong. A machine in zone B can still carry an early bearing defect that only shows up in the high frequency spectrum, which is why many programs add envelope analysis on top of overall levels.

Setting alarms in your CMMS or monitoring system

Most teams set alert at the B/C boundary and danger at the C/D boundary, then tighten them after a few months of baseline data. A rising trend matters more than any single number, so also alarm on rate of change, for example a doubling over a few weeks. If you run SAP PM, Maximo or an ERP maintenance module, store the limits as measurement document thresholds on the measuring point so an out of range reading raises a notification automatically.

Common mistakes

The most frequent error is applying a limit meant for a rigid foundation to a machine on springs or a lightweight frame. Others are mixing RMS and peak readings, measuring on a cover or guard instead of the bearing housing, and using limits for machines under 15 kW as if they came from part 3. Also remember that the table does not cover gas turbines, reciprocating machines or machines with rotating shaft measurements, which fall under other parts of the ISO 20816 family.

Frequently Asked Questions

What are the ISO 10816 vibration zones?

There are four zones. A is newly commissioned machines, B is acceptable for long-term operation, C is unsatisfactory for long-term operation and needs planned repair, and D is severe enough to cause damage. The boundaries are expressed in mm/s RMS and depend on machine class and foundation.

Is ISO 10816 obsolete?

ISO 20816 has been published to replace the ISO 10816 series in stages, but ISO 10816 values are still widely quoted in procedures, contracts and instrument defaults. Check which edition your documents cite and use that one consistently for trending.

Should I use RMS or peak velocity?

ISO 10816 limits are in RMS velocity. If your meter reports peak, convert it before comparing: for a pure sine wave RMS is about 0.707 times peak. For real machine signals the ratio varies, so set the meter to RMS directly where possible.

Does a zone B reading mean the bearing is healthy?

Not necessarily. Overall velocity is dominated by low frequency content such as unbalance and misalignment, while early bearing wear shows at high frequency with small amplitude. Combine overall levels with spectrum or envelope analysis for early bearing defects.

If you want vibration readings from your monitoring system compared with these limits and pushed into your ERP maintenance records automatically, Netray can scope that integration with you.

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