Hi all.
Lately, I have been taking vibration data from a proximity probe. But however, i can't seem to get an accurate reading as what is depicted on the online vibration monitoring panel even though the sensitivity of the sensor is correct. On certain probes the difference would be approx 3 microns while at some other points are more than 5 microns. Anyone encountered this problem before?

Any comments? The normal sensitivity for a displacement probe is 0.007874V/m and 0.003937 rite?

a) How do you know that the vibration monitors are giving 'accurate' readings? Can you calibrate a set of monitors so that they all give exactly the same reading?

b) 3 microns and 5 microns don't represent a big variation. Most machines rarely display vibration amplitudes that are absolutely rock solid and steady, so the differences you are seeing might represent the difference in time between when you took the measurment and when you looked at the monitor.

c) Prox probes are 200mV/mil or 7.874 mV/micron (or 100mV/mil ~ 3.937 mV/micron)

This isn't a big deal if you are trending readings and looking for changes

Is your gear set to RMS? If so it will read less than the monitor. Also what is your Fmax? The monitor may be seeing higher frequency than your collector.