Greenheck Housed Plenum Array , Plug and Plenum Fans (475405) - Manual (Page 11)

11 Housed Plenum Array, Plug and Plenum
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.
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 attached securely.
Greenheck performs a vibration test on all centrifugal
fans before shipping. Three vibration readings are taken
on each bearing in the horizontal, vertical, and axial
directions.
The maximum allowable vibration for models PLG
and APM (belt and direct drive) and APH (belt drive)
is 0.15 in/sec. peak velocity filter-in at the fan rpm per
AMCA Standard 204.
The maximum allowable vibration for model HPA (direct
drive) is 0.10 in/sec. and for model APH (direct drive)
is 0.08 in.sec. peak velocity filter-in at the fan rpm per
AMCA Standard 204.
These vibration signatures are a permanent record
of how the fan left the factory and are available upon
request.
Generally, fan vibration and noise is transmitted to other
parts of the building by the ductwork. To eliminate this
undesirable effect, the use of heavy canvas connectors
is recommended. If fireproof material is required,
Flexweave
TM 1000, Type FN-30 can be used.
Common Sources of Vibration
1. Wheel Unbalance
2. Drive Pulley Misalignment
3. Incorrect Belt Tension
4. Bearing
5. Mechanical Looseness
6. Faulty Belts
7. Drive Component Unbalance
8. Poor Inlet/Outlet Conditions
9. Foundation Stiffness
Routine Maintenance
Once the unit has been put into operation, a routine
maintenance schedule should be set up to accomplish
the following:
1. Lubrication of bearings and motor (see below).
2. Wheel, housing, bolts and set screws on the entire
fan should be checked for tightness.
3. Any dirt accumulation on the wheel or in the housing
should be removed to prevent unbalance and
possible damage.
4. Isolation bases should be checked for freedom
of movement and the bolts for tightness. Springs
should be checked for breaks and fatigue. Rubber
isolators should be checked for deterioration.
5. Inspect fan impeller and housing looking for fatigue,
corrosion, or wear.
When performing any service to the fan, disconnect the
electrical supply and secure fan impeller.
Fan Operation
All fans should be run every thirty (30) days, or at least
“bumped” every thirty days. It is preferred that each
fan is run as this causes all electrical and mechanical
components to get up to temperature, displacing any
formed condensation, redistributes load on bearings,
and redistributes grease in the bearings (motor and
shaft bearings).
Motors
Motor maintenance is generally limited to cleaning
and lubrication. Cleaning should be limited to exterior
surfaces only. Removing dust and grease build up on
the motor housing assists proper motor cooling. Never
wash-down motor with high pressure spray. Many
fractional motors are permanently lubricated for life
and require no further lubrication. Motors supplied with
grease fittings should be greased in accordance with
the manufacturer’s recommendations.
CAUTION
• Always check the fan RPM when adjusting the
operating frequency. Do not exceed maximum
class fan RPM of the wheel.
• When operating conditions of the fan are to be
changed (speed, pressure, temperature, etc.),
consult Greenheck to determine if the unit can
operate safely at the new conditions.
CAUTION
When performing any service to the fan, disconnect
the electrical supply and secure fan impeller.