need some Advice on an Overhung fan arrangement.
110kw Motor 1480rpm fixed speed, belt driven. The pulley arrangement is 1:1, making the fan speed at 1480rpm. It has a filter system before it, so it is essentially sucking out clean air which it then is exhausting to atmosphere. Historical data shows this fan has had high Horiz 1x going back to 2014. Cures to try and fix it back then included balancing the fan and putting anti-vibration mounts on the frame. This has taken the readings down from about 20mm/s to around 8-10mm/s.
so now I'm investigating this and want to know what could be possibly causing such a fault. My initially view is pulley eccentricity. I have used phase analysis, but this wasn't a conclusive find (i measured vertically underneath the bearing on the pedestal, and horiz and got 167 degrees) i then measured top of the bearing and horiz and got 45 degrees. I might be doing it totally wrong!
I Will dti gauge the pulleys in due time, but I haven't had a chance to switch off the fan due to production demands. i have ruled out it being balance issue due to the fairly low axial and vertical readings, am I wrong for doing that ?
The De fan vibration is reading as follow
H: 10.19mm/s at 1x
v: 5.7mm/s at 1x
A:3mm/s at 1x
NDE fan vibrations reading as follows:
H: 7.83mm/s at 1x
v: 3.3mm/s at 1x
A: 2.6mm/s at 1x
De Fan bearing Housing: 45.6C
NDE Fan bearing Housing 40C
Is there anything I am missing, any other suggestions for possible issues or ways to narrow down what it could be?