24
Daikin
IM 777-7
Operation Guidelines
Fan Vibration Levels
Each unit as shipped is trim balanced to operate smoothly. To
provide satisfactory operation after shipping and installation,
use the accepted industry guidelines for field balancing fans.
See
Table 20
.
Note: Excessive vibration from any cause contributes to premature fan and
motor bearing failure. Monitor overall vibration levels every six
months of operation. An increase in levels is an indication of potential
trouble.
Vibration Causes
1
Wheel imbalance.
a
Dirt or debris on wheel blades.
b
Loose set screws in wheel hub or bearing-to-shaft.
c
Wheel distorted from overspeed.
2
Bent shaft.
3
Drive faulty.
a
Variable pitch sheaves—Axial and radial runout of
flanges; uneven groove spacing; out of balance. Also
similar faults in driven sheave.
b
Bad V-belts; lumpy, or mismatched; belt tension too
tight or too loose.
4
Bad bearings, loose bearing hold-down bolts
5
Motor imbalance
6
Fan section not supported evenly on foundation
Table 20: Vibration Levels
Fan speed (rpm)
Vibration
800 or less
5 mils maximum displacement
801 or greater
0.20 in/sec. maximum velocity
