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11
Operation
Prior to Start-Up
1––Make sure all the pillow blocks are fixed to the hub boss—if any
movement of the blocks is detected, do not operate the fan and
check the torque of bolts 15.
2––Rotate fan to check tip clearance is in accordance with the speci-
fied value (tip clearance ratio x/D, where x = the distance from the
blade tip to the fan ring and D = the rotor diameter). The gap between
blade tip and fan ring must be measured along blade axis.
3––Check gear box oil level or belt tension to be as indicated by
the manufacturer.
4––Remove all tools from the area.
5––Connect motor to power supply.
6––Start fan for a few seconds, and then switch it off. While the fan
is still turning, check that the direction of the blade rotation is cor-
rect (see Rotation and Flow Direction).
Post Start-Up
1––Check power absorption: if excessive, reduce the blade pitch
angle until the desired power is achieved (set the new pitch on all
the fans of a same structure); if lower than predicted, increase the
blade pitch angle until the desired power is achieved (set the new
pitch angle on all the fans of a same structure).
Power absorption varies in inverse proportion to the air tem-
perature.
2––Check the vibrations level in the position shown in Figure 5.
Do not exceed the most restrictive amplitude values between the
limits imposed by the normative of the structure where the fan is
installed and the limits imposed by the VDI 2056 normative. In this
case, shut down the unit and trace the cause of such excessive
vibration by referring to section Possible Causes of Vibration in the
following section.
Note