Appendix: Machinery Classification
When evaluating machinery and equipment it is useful to know their classification range
and group type. There are four machine groups and classification ranges recognized
internationally. The limits for vibration severity (mm/s) are shown in the Tables below:
GROUP K – Small Machinery up to 15KW (for example, production motors)
Testing Status
Good
Acceptable
Permissible
Dangerous
Vibration Severity (mm/s)
0 to 0.71
0.72 to 1.80
1.81 to 4.5
Greater than 4.5
GROUP M – Medium-sized Machinery up to 75KW (for example, motors without
special foundations)
Testing Status
Good
Acceptable
Permissible
Dangerous
Vibration Severity (mm/s)
0.00 to 1.12
1.13 to 2.80
2.81 to 7.10
Greater than 7.10
GROUP G – Large Machinery on Heavy Foundations
Testing Status
Good
Acceptable
Permissible
Dangerous
Vibration Severity (mm/s)
0.00 to 1.80
1.81 to 4.50
4.51 to 11.20
Greater than 11.20
GROUP T – Large Turbo Machinery on Special Foundations
Testing Status
Good
Acceptable
Permissible
Dangerous
Vibration Severity (mm/s)
0 to 2.80
2.81 to 7.10
7.11 to 18.00
Greater than 18.00
6
Model 407850 Version 1.2 December 2005
EXTECH [ EXTECH INSTRUMENTS CORPORATION. ]
