Rotor Dynamics and Vibration Analysis

Beeause the study of rotor dynamies and vibration analysis is eontained in numerous texts only some basie troubleshooting tables and guidelines are presented. They deseribe the most eommon peaks in a typieal vibration analysis speetrum and how these symptoms might be mitigated. 

Of all vibration frequeneies, the most dangerous are the synehronous vibrations, where an externally foreed vibration exeites one of the natural (resonant) frequeneies in the maehine. Campbell diagrams eonstrueted by the manufaeturers will help the operator avoid these frequeneies during run-up or eoimuissioning of tlie maehine in question. 

The limits expressed in Table 7-3 (x-axis = operating speed in rpm, y-axis = overall vibration level in mils [peak to peak]) are based on experienee in refineries. The guide refleets the typieal proximity probe installation elose to and supported by the bearing housing and assumes the main vibration eomponent to be of [lx rpm] frequeney. The 

Readings must be taken on maehined surfaees with runout below. 5 mil up to 20,000 rpm, and below. 25 mil above 12,000 rpm. 

Maximum allowable vibration limits on bearing housings in ips (peak) for operation up to earliest possible corrective shutdown 

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