Fan Issues: Balance of fan wheel. Above .2 in/sec velocity
pk. should be balanced to less than .1 in/sec velocity pk. Belt related vibration with
several harmonics. Again levels above .2 in/sec velocity pk should be attended to by replacement of worn sheaves, new belts
and laser alignment. Belt alignment. Drive sheave
unbalance and worn sheave likely to cause belt related vibration. Check for rust on
all joints on higher vibration units. These usually mean cracks that need attention.Exhaust
fan style units Watch for belt related issues. Refer to the belt calculator frequency
when analyzing the spectral plot. Balance is usually more difficult on these type fans.
If you can use two plane I prefer having outboard and near side wheel as same plane and drive bearing and outside wheel refered
to as the same plane. Try not to have adjustable pitch sheaves on motor drive. Motors usually vibrate more than fan bearings. Normally unit has a weak motor base. Vibration Faults: Balance on wheel Belt
pass faults and harmonics Balance of motor Alignment
between drive sheaves.