alarm level / limits standard ?

[analyst34]

Can anyone tell me if there is a beginning standard of alarm limits or level criteria on bearings up to 75.5xrpm prior to making my own limits after further trending.What is a good starting point.
Will peakvue be the same or slightly different?

 

[sms]

The Vibration Institute uses the following velocity limits
in in/sec
rms peak
Acceptance of new equip <0.8 <0.16
unrestricted operation <0.12 <0.24
surveillance 0.12-0.28 0.24-0.7
Shutdown immediately >0.28 >0.7

 

[MachineryWatch]

Are you asking for general machine condition alarms based on measurements made on the bearings, or alarms that apply specifically to the condition of the bearings? They really are 2 different things. The Vibration Institute guidelines are certainly valid for the general machine condition assessment (as are standards from other sources such as ISO and even standards established by and recommended by some private firms). The condition of rolling element bearings is quite another thing. The bearing condition determination is made not so much on overall amplitudes, but rather on the development of specific "bearing-related" frequencies in the spectrum. Generally speaking we see more and more of these frequencies in the spectrum and more indications of modulation (sidebands) as the bearing wear continues to worsen. The amplitudes may remain quite small in spite of severe bearing condition deterioration. This is especially true with relatively slow speed (<600 RPM) shafts. The total energy from these low amplitude bearing frequencies may have little actual impact on the overall vibration level.

PeakVUE is an excellent tool, when properly configured, but it's value is in it's ability to make the bearing-related frequencies more visible in the spectrum while diminishing the high-amplitude frequencies that normally dominate the velocity spectrum. PeakVUE amplitudes have no discernable relationship to the velocity amplitudes measured because it is such a heavily "massaged" or processed signal.

The PeakVUE amplitudes are very dependent on things like the transmission path to the sensor from the source of the energy and the filters and other parameters chosen by the analyst for the measurement.

This is not the definitive answer you may have been looking for, but I hope it is helpful, none-the-less.

Skip Hartman

http://www.machinerywatch.com