Unit Start-Up; Radial Gap And Alignment; Vibration - Greenheck DFD Series Installation, Operation And Maintenance Manual

Unit Start-Up

DANGER
High voltage electrical input is needed for this
equipment. This work should be performed by a
qualified electrician.
DANGER
Cet appareil nécessite une alimentation électrique
sous haute tension. Confier ce travail à un électricien
qualifié.
DANGER
Disconnect and secure to the "OFF" position all
electrical power to the fan prior to inspection or
servicing. Failure to comply with this safety precaution
could result in serious injury or death.
DANGER
Pour écarter les risques de blessure grave ou de mort,
débrancher et verrouiller l'alimentation électrique en
position « Arrêt » avant tout contrôle ou entretien.
1. Disconnect and lock-out all power switches to fan.
2. Check all fasteners, set screws and locking collars
on the fan, wheel, bearings, drive, motor base and
accessories for tightness.
3. Rotate the fan wheel by hand and assure no parts
are rubbing.
4. Check for bearing alignment and lubrication.
5. Check the V-belt drive for proper alignment and
tension.
6. Check all guarding (if supplied) to ensure that it is
securely attached and not interfering with rotating
parts.
7. Check all electrical connections for proper
attachment.
8. Check housing and ductwork, if accessible, for
obstructions and foreign material that may damage
the fan wheel.
9. Check for proper wheel rotation
by momentarily energizing the fan.
Rotation should correspond to the
rotation decal affixed to the unit
(counter clockwise rotation is correct
as viewed from the fan inlet).
One of the most frequently encountered problems
with fans are motors which are wired to run in the
wrong direction. This is especially true with 3-phase
installations where the motor will run in either direction,
depending on how it has been wired. To reverse rotation
of a 3-phase motor, interchange any two of the three
electrical leads. Single phase motors can be reversed
by changing internal connections as described on the
motor label or wiring diagram.
8 Mixed Flow
10. Fans with multi-speed motors should be checked
on low speed during initial start-up.
11. Ensure proper wheel location for radial gap, and
alignment. See Radial Gap and Alignment section
below.
12. Grease may be forced out of the bearing seals
during initial start-up. This is a normal self-purging
feature of the bearing.
13. Check for unusual noise, vibration or overheating
of bearings. Refer to the Troubleshooting section of
this manual if a problem develops.

Radial Gap and Alignment

Efficient fan performance can be maintained by having
the correct radial gap, overlap and alignment. These
items should be checked before start-up and after the
fan has been in operation for 24 hours.
Radial Gap - Adjust inlet cone position such that the
radial gap between the wheel cone and inlet cone is
evenly distributed around the wheel.
Alignment - If necessary,
adjust wheel position by
loosening the wheel hub from
the fan shaft so that a straight
edge held tight to the wheel
cone just touches the inlet
cone. Refer to drawing.

Vibration

Excessive vibration is the most frequent problem
experienced during initial start-up. Left unchecked,
excessive vibration can cause a multitude of problems,
including structural and/or component failure.
The most common sources of vibration are:
Wheel unbalance
Drive pulley misalignment
Incorrect belt tension
Bearing misalignment
Mechanical looseness
Faulty belts
Foundation stiffness
Drive component unbalance
Mixed Flow
Poor inlet/outlet conditions
Many of these conditions can be discovered by careful
observation. Refer to the Troubleshooting section of
this manual for corrective actions. If observation cannot
locate the source of vibration, a qualified technician
using vibration analysis equipment should be consulted.
If the problem is wheel unbalance, in-place balancing
can be done providing there is access to the fan wheel.
Any correction weights added to the wheel should be
welded to either the wheel back (single-plane balance)
or to the wheel back and wheel cone (two-plane
balance).
Straight Edge
Wheel
Cone
Radial
Gap
Inlet Cone