General Resonance Advice

[flacrkr]

I have a request for VERY basic advice/ideas about a possible resonance situation. I was asked to take initial vib. data on a calcining oven we are purchasing. While taking data I noticed fluctuating amplitudes (.2 to .65 IPS PK) on 2 of the 8 zones. The 8 fans are plug fans mounted on the side of the oven horizontally. They all rotate CW, zones 1,2,4 &5 at same rpm. 3,6,7 &8 within 75 rpm of others. I have not been allowed to perform more than cursory data collection since technically the oven does'nt belong to us yet. Does anyone have experience with this config. or any GENERAL assumptions? Is it "likely" to have potential for resonance problems?

 

[TPL]

EVERYTHING has the potential for resonance - unless you carry out a proper investigation you simply won't know.

One possibility that you need to consider with several machines that are located close to each other (or mounted on a common structure) and running at the 'same' speed is that you get a beating effect: each individual fan running alone might have acceptable levels of vibration, but when several are operated together the combined vibration shows much higher levels that come and go in a periodic manner.