Installation, Operation & Maintenance Manual
IM-995
17
Fan Bearing Maintenance (refer to safety section)
Proper lubrication of the fan drive bearings helps assure maximum bearing life. All fans are equipped with decals indicating the
recommended relubrication intervals for normal operating conditions. Refer to the Bearing Installation section for the lubrication
schedules for ball bearings, solid pillow block spherical roller bearings and split pillow block spherical roller bearings. Note that all
speeds shown do not apply to all shaft sizes in that group. Consult the factory if in doubt of maximum speed for a particular bearing.
Note that every installation is different and the frequency of relubrication should be adjusted accordingly.
Use 1/2 to 1/3 of the listed lubrication interval for high moisture applications. For vertical shaft mounts or dirty conditions use 1/2
the lubrication schedule.
Observation of the conditions of the grease expelled from unit ball or roller bearings at the time of relubrication is the best guide
as to whether regreasing intervals and amount of grease added should be altered. Spherical roller bearings with split pillow block
housings should not be lubricated until grease purges or overheating may result. Follow the lubrication interval and amount noted in
the Bearing Installation section. Spherical roller bearings with split pillow block housings should be serviced once per year. Remove
cap, clean out old grease and replace by filling the bottom half of the housing 1/3 full.
Greases are made with different bases. There are base greases, lithium base, sodium base, polyurea, etc. Avoid mixing greases with
different bases. They could be incompatible and result in rapid deterioration or breakdown of the grease. The lubrication sticker
identifies a list of acceptable lubricants. All bearings are filled with a lithium complex grease before leaving the factory. When the fans
discharge because leakage will cease when the excess grease has worked out. Sometimes the bearings have a tendency to run hotter
during this period. This is no reason for alarm unless it lasts over 48 hours or temperatures exceed 200°F. When relubricating, use a
sufficient amount of grease to purge the seals. Rotate bearings by hand during relubrication. If extended lubrication lines are fitted,
lubricate the bearings while the fan is operating if it is safe to do so.
Impeller and Shaft Maintenance (refer to safety section)
Periodically inspect the shaft and impeller for dirt buildup, corrosion and signs of excess stress or fatigue. Clean the components. If
the impeller is removed for any reason, make sure that it is securely attached to the shaft before restarting the fan.
Structural Maintenance (refer to safety section)
All structural components or devices used to support or attach the fan to a structure should be checked at regular intervals. Vibration
isolators, bolts, foundations, etc., are all subject to failure from corrosion, erosion and other causes. Improper mounting can lead to
poor operation characteristics or fan fatigue and failure. Check metallic components for corrosion, cracks or other signs of stress.
Concrete should be checked to insure the structural integrity of the foundation.
Duct Connections
(refer to safety section)
The fan support structure is normally not designed to carry
loads imposed by the weight of ducts, silencers, stacks, etc.
Supporting these loads on the fan can cause housing distortion
and may cause performance or vibration problems. Use of
flexible connections is recommended for all fans and imperative
when using vibration isolation or handling high temperature
gases.
Centrifugal Fan with
Vibration Isolation & Flexible
Duct Connectors
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