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MVA 02 rev 5 - December 2017
4.- On both hub types, turn the extractor handle to
detach the impeller (Photo 30
– for reasons of
simplicity only the impeller with an extraction groove
is shown).
Photo 30
5.- Lift and remove the impeller, after removing the
fixing bolts in the case of the hub with threaded
extraction holes.
10.2.3 Adjusting blade angle
Blade angle adjustments may alter impeller balance. It is therefore advisable to check impeller balance after
adjusting blade angles, to prevent any abnormal vibration due to blade angle adjustment. Note that an
increase in blade angle also produces higher power absorption by the fan.
CAUTION:
Check that the available installed power has not been exceeded by checking power
absorption while running, and consult the data on fan characteristics to assess the permitted
variation.
To facilitate this operation, the impeller must be removed from the shaft on which it is mounted (see previous
paragraphs 10.2.1 and 10.2.2).
Without removing them, slacken nuts 2 on the hub
assembly. Rotate the blades to adjust blade angle
as desired. Check that all blades are at the same
angle. Tighten fixing nuts 2 (Photo 31) on the hub
assembly until the tightening torque indicated in
Chart 10.1 for bolts with class 8.8 resistance is
reached, and then use a thread locking compound.
Photo 31
