KutupASP DijitalISO 20816 vibration severity zones classify how acceptable a machine's broadband vibration is. Zone A is typical of newly commissioned machines, zone B is acceptable for unrestricted long-term operation, zone C is usually unsatisfactory for continuous operation, and zone D is severe enough to cause damage. The boundaries depend on the machine group.
The ISO 10816 series was revised into the ISO 20816 series. It evaluates a machine's broadband vibration severity. Measurements are usually taken on bearing housings under steady operating conditions, and the value is most often velocity RMS in mm/s.
The boundaries depend on machine group, size and power, and support stiffness. Check the relevant part of the standard for your machine class. This page gives no numeric limits; take them from the standard.
This example shows baseline reasoning without using a zone boundary. A hypothetical pump is measured at the same bearing housing point, at the same load and speed. The baseline recorded at commissioning is 2.0 mm/s RMS.
Some time later, the same measurement reads 3.2 mm/s RMS.
A 60 percent rise over baseline is a reason to investigate, whatever zone letter applies. Before looking at a zone boundary, find the cause: misalignment, unbalance, looseness or a change in load are all possible.
The zone letter is easy to misuse:
Zone D describes a level severe enough to cause damage. It is decision-support information, not an automatic shutdown rule. Ask whether the trend is rising quickly, what the spectrum shows, and what the production and safety risk is. Maintenance and production should decide together.
New machines are usually measured in zone A, but that is not a guarantee. Alignment, mounting, foundation or bearing issues can raise the first reading. Record the first measurement as the baseline and find out why it differs.
Example numbers are hypothetical, not measured field results.
After reading, you can track a machine's broadband vibration against its own baseline and read the ISO 20816 zones in the right context, without treating a zone as a fault diagnosis.
Data from a vibration sensor cannot be interpreted without knowing which quantity it measures, which frequency range it sees and how it was mounted.
