Greenheck AX (464664) - Manual (Page 5)

5 Axial Fan
Performance Adjustments
Field Performance Adjustments
The performance of an AX fan can be adjusted through
the use of a variable speed drive (VFD) or adjusting
the fan pitch. Both can be effectively used for final air
balancing. Note that any change, increase or decrease
in fan speed (RPM) or blade pitch, can represent a
substantial increase in power required from the motor.
Check motor load amperage and compare to nameplate
rating when changing the fan speed or blade pitch.
Adjusting Performance with a Variable Frequency
Drive (VFD)
Before wiring a VFD, determine that the motor is
compatible with this type of equipment. Connecting a
VFD to a non-compatible motor may reduce the life of
the motor. Additionally, it is important to properly ground
fans being wired with a VFD. For more information
on these subjects, refer to Greenheck document “Are
Bearing Currents Causing Your Motor Failures?” located
at www.greenheck.com. Click on Library, Application
Articles, and use the keyword “VFD”. Greenheck is not
responsible for improper wiring of a VFD or for potential
motor damage as a result of operating a fan over its
maximum operating frequency.
Adjusting Performance through Blade Pitch
Adjustments
The blade pitch can be adjusted without removing the
propeller from the fan casing. Steps to adjust the blade
pitch are as follows:
1. Determine the new blade pitch required with your
local Greenheck representative. Verify that the
motor has sufficient capacity to handle the new
power requirements.
2. Disconnect and lock out all power to the fan to
prevent accidental start-up.
3. Gain access to the propeller side of the fan. This
may require removing the fan from the existing duct
system or dismantling ductwork to gain access.
4. Loosen the blades to the point where they can be
rotated in the hub. Hub and blade fastening vary by
fan size. Hub styles and bolt torque requirements
are provided. Do NOT pound on the blades to
adjust the pitch. They should be snug, but movable
by hand.
5. Use the blade pitch protractor found on
Greenheck’s website (www.greenheck.com) to
adjust the pitch. Follow the directions stated on the
guide for determining blade pitch.
6. Adjust one blade to the desired pitch angle and
remove the protractor sheet.
7. Use a marker to trace the profile of the blade on the
fan housing.
8. Adjust the remaining blades to the traced profile.
Torque Specifications for Bushings and Propeller
Bolts
HUB SIZE: 160 mm
Bushing bolts 9 ft-lb / 12.2 N-m
Propeller bolts 7 ft-lb / 9.5 N-m
HUB SIZE: 190 mm
Bushing bolts 16 ft-lb / 21.7 N-m
Propeller bolts 7 ft-lb / 9.5 N-m
HUB SIZE: 275 mm
Bushing bolts 16 ft-lb / 21.7 N-m
Propeller bolts 21 ft-lb / 28.5 N-m
HUB SIZE: 400 mm
Bushing bolts 27 ft-lb / 36.6 N-m
Propeller bolts 40 ft-lb / 54.2 N-m
HUB SIZE: 533 mm
Bushing bolts 40 ft-lb / 54.2 N-m
Blade Nuts 125 ft-lb / 169.5 N-m
9. Retighten the hub to the torque specs detailed
below per hub size.
10. Reinstall the fan or any duct pieces that were
removed.
11. Review the Operation and Start-Up procedures
listed earlier in this manual.
12. After start-up, make a final check of the fan amps
to ensure the motor is not overloaded.
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