AMCOT ST SERIES FIBERGLASS COOLING TOWER
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GENERAL MAINTENANCE
Mechanical System – Fan Assembly
Fan Assembly & Balancing
For ST-60 to ST-1500 fan assemblies, since they are adjustable pitch type of fans, it is important that
they be properly set and balanced at the job site prior to operating to prevent damage to your
equipment.
To set the pitch of the fan blades, you will loosen
the U-bolt fastener(s) which secure the blade to
the hub. On each fan blade there is a single mark
or indicator line cast into the fan blade which
when attached to the hub, can be lined up with
the proper marking on the hub which indicates
proper pitch.
On the hub, you will identify a series of markings.
There should be seven (7) total markings. The
center marking is longer than the other six (6).
This center mark is position “0”.
If you rotate the fan blade mark to the right
when it is secured to the hub, this will represent
the “minus” direction for pitch which increases
the blade angle. Increasing blade angle will in
turn increase airflow through the tower. It is
important to note that increasing air flow will also
mean adding additional load to the motor which
will cause the amp draw to go up. Keep this in
mind, because it is important that the motor amp
draw during operation should not exceed the
amp draw specified on the motor nameplate.
If you rotate the fan blade mark to the left when it is secured to the hub, this will represent the “plus”
pitch which decreases blade angle and will in turn decrease air flow. This in turn lowers amp draw on
the motor.
Once the fan blades are installed onto the hub, align the blade mark with the center marking on the
hub. This represents a fan pitch of zero (0). A chart on page 32 provides the starting pitch for adjustable
pitch fans. Once the blade is in the proper position, tighten the U-bolts to secure the fan blade to the
hub. Do not overtighten the fasteners otherwise you will risk damaging the fan.
Proper Torque on fan blade fasteners is Critical. Refer to the Fan Assembly Chart on page 34.
DO NOT OVERTIGHTEN!
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