Field case · Condition monitoring
Electrostatic precipitator fan at 113 mm/s RMS: a horizontal-to-vertical ratio that gave away the looseness
Quick answer
A fan with a long history of high vibration, after a new motor, bearings, housing, rotor and shop balance, read 113 mm/s RMS at one point. The reading was five times the vertical at the same bearing, and the log-scale spectrum showed a harmonic ladder: structural looseness.
What the case covers
- The history
- What the survey showed
- Why the log scale mattered
- What to take from it
Takeaway. When a machine has been repaired three ways without effect, look at the support. A 5:1 horizontal-to-vertical ratio and a log-scale harmonic ladder pointed there.
Read the full case, with the data and the numbers