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Reply to "I.D Fan strange Balancing response"

@Registered Member posted:

Filtered vibrations levels at 1xSS were very low before balancing (highest was 4 mm/sec or 0.16 in/sec). The 1xSS was not the dominant frequency in velocity spectra, so it has minimal affect on the overall velocity levels. Why are you doing balancing? If you must do balancing, then why not do a single plane solution for only Plane 2 that had roughly 3x higher vibration level levels and similar phase to Plane 1? If amplitude and phase are changing a small amount, then averaging would help balance results. If there are large variations, then looseness in bearing or structure should be corrected first. Perhaps I am not understanding all of your numbers!

Walt

Walt, I'm seeing numbers in the tabulated data that are in excess of the "...very low before balancing (highest was 4 mm/sec or 0.16 in/sec)" that you mention.  In the initial run I'm seeing 7.93 mm/sec in the "FAN N.D.E HORIZONTAL".  In addition, based on the provided data, that likely is mm/sec RMS.  7.93 mm/sec = 0.31 in/sec and if we bump that up it is 0.44 in/sec peak.

The data seems very erratic as well.  I see by one of the provided spectrums the 1X (975 cpm) is about 2.45 mm/sec for the same measurement point.  The overall is 6.072 mm/sec and there is a substantial amount of higher frequency above 5 kHz.  All this makes me wonder if the transducer is a hand held device, something I personally would not use in balancing.

RM
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