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ISO 2372
Vibration severity measurement according to ISO 2372 is a broad band measurement over the frequency
range 10 to 1000 Hz. It returns the RMS value of vibration velocity in mm/s (or inch/s). This value is
representative of the energy contents of machine vibration, and thus of the destructive forces acting on
the machine. It is widely regarded as a good and easy to obtain indicator of general machine condition.
Evaluation of machine condition
The evaluation consists of a comparison of the measured value with the ISO limit values recommended
for 6 different classes (see definition on the next page).
The majority of industrial machinery belongs to the vibration classes 2, 3, and 4:
Class II: Medium size machines without special supports
Class III: Large size machines on rigid supports
Class IV: Turbomachines and large machines on flexible supports
For example, most smaller process pumps in a chemical plant would be Class 2. A 100 kW fan on a
concrete foundation would be Class 3. However, the same fan fastened to the less rigid metal deck of
a ship could be considered as Class 4.
Class 1 refers to independent parts of machines, for example electric motors up to 15 kW. Classes 5
and 6 are used for heavy reciprocating prime movers and machines which are intended to vibrate, such
as vibrating screens.
VibChecker is programmed with the ISO limit values and will evaluate the measuring result, provided
the ISO machine class number is input in the
ISO setup
display. On the instrument, a green condition
indicator will be shown for good and acceptable ISO values, a yellow indicator for just tolerable, and a
red one in cases of unacceptable values.
Summary of Contents for VibChecker
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