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15.1 ISO 10816 Standard Comparison
The ISO 10816 Standards provide guidance for evaluating vibration
severity in machines operating in the 10 to 200 Hz (600 to 12,000
RPM) frequency range. Examples of these types of machines are small,
direct‑coupled, electric motors and pumps, production motors, medium
motors, generators, steam and gas turbines, turbo‑compressors,
turbo-pumps and fans. Some of these machines can be coupled rigidly
or flexibly, or connected through gears. The axis of the rotating shaft
may be horizontal, vertical or inclined at any angle.
Machinery class designations are:
Class l:
Individual parts of engines and machines integrally connected
to the complete machine in its normal operating condition. (Production
electrical motors of up to 15 kW are typical examples of machines in
this category.)
Class ll:
Medium-sized machines (typically electrical motors with 15
kW to 75 kW output) without special foundations, rigidly mounted
engines or machines (up to 300 kW) on special foundations.
Class lll:
Large prime movers and other large machines with rotating
masses mounted on rigid and heavy foundations which are relatively
stiff in the direction of vibration measurement.
Class lV:
Large prime movers and other large machines with rotating
masses mounted on foundations which are relatively soft in the
direction of vibration measurement (for example, turbo‑generator
sets, especially those with lightweight substructures).
Note:
These ISO 10816 Standard classes do not apply to prime movers
or driven equipment in which the major working components have a
reciprocating motion.
15.2 Trend Comparison
The most efficient and reliable method of evaluating vibration severity
is to compare the most recent reading against previous readings for
