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Vibration severity zones per ISO 20816-3 and ISO 10816

Place an RMS vibration velocity reading in zone A, B, C or D for the machine group, and get alarm and trip limits from its baseline. Free, no sign-up.

  • Instant result
  • Formula and standards shown
  • On desktop and phone

Pre-filled example

A 75 kW motor on a rigid support, at 1,500 rpm, measured at 2 mm/s, with a baseline of 1.8 mm/s recorded in good condition.

kW
rpm
mm/s
mm/s

Result

BZone

Vibration alarm at 2.5 mm/s, trip at 5.6 mm/s

Machine group
Group 2, 15 to 300 kW
A/B boundary
1.40mm/s
B/C boundary
2.80 mm/s
C/D boundary
4.50 mm/s
Alarm threshold
2.5 mm/s
Alarm ceiling
3.5 mm/s
Trip
5.6 mm/s
  • Caution : Manufacturer or contract values prevail; these zones are not acceptance values.
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Vibration alarm limits set on the measurement point

Here, the calculator is free and the result is gone when you close the page. In Reglova, it is attached to the work order on the right machine: you find it again at the next breakdown, and on audit day.

The CMMS software comparison, our gaps included
  • Attached to the work order with its inputs: the server recalculates it, it stays verifiable.
  • On the technician's phone, even without a network.
  • In the machine's history, for the next breakdown.
  • The alarm limit is set on the machine's measurement point.
  • The result becomes a checklist step of the work order.
  • The asset's nameplate data pre-fills the calculation.
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Reglova · Calculations · Work order WO-AT01-04219
Silent video, 33 s: from the work order for an oil leak on a shear cylinder, the tightening torque of an M12 bolt, then "Attach to the work order". A step to tighten it to 93.1 N·m lands in the checklist (step text from the French demo data). Watch the video

When to check a reading against ISO 20816-3

  1. 01

    Interpret a reading taken with a vibration pen during a round.

  2. 02

    Set the limits of a measurement point followed over time, from the machine's baseline.

  3. 03

    Decide whether a machine in zone C can wait for the next planned stop.

Good to know

Manufacturer or contract values prevail: these zones are not acceptance criteria. At 15 kW or below, the machine falls outside ISO 20816-3 and the calculator uses the ISO 10816-1 class I zones.

Machine groups, zone limits and alarm formula

ISO 20816-3 classifies the RMS vibration velocity measured on the bearings of an industrial machine into four zones: A (newly commissioned), B (unrestricted long-term operation), C (limited operation) and D (risk of damage). The calculator picks the machine group from its power and support, places the reading, and suggests an alarm limit and a trip limit.

Formula · Reference documents

Alarm = min(baseline + 0.25·B/C ; 1.25·B/C) ; trip = 1.25·C/D

ISO 20816-3:2022, annex A ; ISO 10816-1, annex B (class I)

Inputs and accepted ranges
InputUnitAccepted rangeExample
Machine powerkW0.1 to 50,00075 kW
Support2 optionsRigid
Speedrpm120 to 30,0001,500 rpm
Vibration velocity, RMSmm/s0 to 1002 mm/s
Baselinemm/s0 to 501.8 mm/s
Calculated results
  • Zone
  • Machine group
  • A/B boundarymm/s
  • B/C boundarymm/s
  • C/D boundarymm/s
  • Alarm thresholdmm/s
  • Alarm ceilingmm/s
  • Tripmm/s
What the calculator flags
  • Manufacturer or contract values prevail; these zones are not acceptance values.
  • 15 kW or less: outside ISO 20816-3, ISO 10816-1 class I zones.
  • Between 120 and 600 rpm: measure over 2 to 1,000 Hz.

Vibration readings and the work orders they trigger

  • Breakdowns reported by QR code
  • Work orders on the phone, even without a network
  • Mandatory inspections reminded by email
  • Audit file as a PDF, in one click
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