Twin City Centrifugal Fume Exhaust Fans - IM-390 - Manual (Page 6)

6 Twin City Fan IM-390
Greases are made with different bases. There are syn-
thetic base greases, lithium base, sodium base, etc.
Avoid mixing greases with different bases. They could be
incompatible and result in rapid deterioration or break-
down of the grease. The lubrication sticker identifies a
list of acceptable lubricants. All bearings are filled with
a lithium-based grease before leaving the factory. When
the fans are started, the bearings may discharge excess
grease through the seals for a short period of time. Do
not replace the initial discharge because leakage will
cease when the excess grease has worked out. Some-
times the bearings have a tendency to run hotter during
this period. There is no reason for alarm unless it lasts
over 48 hours or gets very hot (over 200°F). When re-
lubricating, use a sufficient amount of grease to purge
the seals. Rotate bearings by hand during relubrication.
DRIVE MAINTENANCE AND INSTALLATION
V-belt drives need periodic inspection, retensioning, and
occasional belt replacement. When inspecting drives, look
for dirt buildup, burrs or obstructions that can cause pre-
mature belt or drive replacement. If burrs are found, use
fine emery cloth or a stone to remove them. Be careful
that dust does not enter the bearings. Check sheaves for
wear. Excessive slippage of belts on sheaves can cause
wear and vibration. Replace worn sheaves with new
ones. Carefully align sheaves to avoid premature sheave
failure. Inspect the belts for wear. If fraying or other wear
is observed to be mostly on one side of the belts, the
drives may be misaligned. Reinstall the drives according
to the following instructions:
1. Slip (do not pound) proper sheave onto correspond-
ing shaft. CAUTION: Placing fan sheave on motor can
overspeed wheel and cause structural failure.
2. Align sheaves with straightedge extended along
sheaves, just making contact in two places on outside
perimeters of both sheaves.
3. Tighten sheave bolts (or setscrews if appropriate).
Table 1 can be used to determine the amount of
torque required.
4. Install a matched set of belts. Adjust the motor posi-
tion to obtain slack, install, and tighten belts. Using a
pry bar will damage belts.
5. Tighten belts to proper belt tension. Ideal tension is just
enough so that the belts do not slip under peak load.
When using drive tensioning data supplied by V-belt
drive manufacturers, new belts can be tensioned to a
value 50% greater than for normal operation. This will
reduce retensioning requirements after break-in. Re-
check sheave alignment after tensioning.
6. After initial installation of belts, recheck belt tension
again after a few days. (New belts require a break-in
period of operation.)
7. When replacing belts, replace the entire set. After initial
replacement and tensioning, recheck belt tension after
a few days. (New belts require a break-in period of
operation.) Never use belt dressing on any belts.
8. Fans that have motors and drives mounted at the fac-
tory are trim balanced prior to shipment. This is not
possible on units that are shipped without motors and
drives. The addition of drive components in the field
can create unbalance forces. Twin City Fan & Blower
recommends final balancing of the unit after the drive
components are installed. Failure to do so may void
the warranty.
WHEEL AND SHAFT MAINTENANCE
Periodically inspect the shaft and wheel for dirt buildup,
corrosion, and signs of excess stress or fatigue. Clean
the components. If the wheel is removed for any reason,
make sure that it is securely attached to the shaft before
restarting the fan.
STRUCTURAL MAINTENANCE
All structural components or devices used to support or
attach the fan to a structure should be checked at
regular intervals. Vibration isolators, bolts, foundations,
etc., are all subject to failure from corrosion, erosion,
and other causes. Improper mounting can lead to poor
operation characteristics or fan fatigue and failure. Check
metallic components for corrosion, cracks, or other signs
of stress. Concrete should be checked to insure the
structural integrity of the foundation.
FAN OPERATION—SAFETY
For general safety practices for air moving equipment,
see AMCA Bulletin 410. AMCA Bulletin 410 and other
AMCA publications can be purchased from AMCA’s
website at http://www.amca.org/store. Twin City Fan &
Blower offers many safety accessories. These safety
devices include (but are not limited to) belt guards,
shaft guards, inlet and discharge screens. The use and
suitability of safety devices is the responsibility of the
purchaser.
Facility related safety conditions include fans’ acces-
sibility and location. How easily can nonservice person-
nel access the unit? Is the fan in a hazardous duty
environment? Was the unit ordered for this duty? Other
concerns must also be addressed. All fans should be
powered through switches which are easily accessible to
service personnel from the fan. Every switch should have
the ability to be “locked out” by the service person and
the key to be retained by this person to prevent acci-
dental powering of the fan while service is in process.
TROUBLESHOOTING GUIDELINES
Use current safety practices when investigating fan or
system performance problems. General safe practices and
performance troubleshooting guidelines can be found in
AMCA Publications 410 and 202, respectively. Fan appli-
cation and field measurement procedures can be found in
AMCA Publications 201 and 203.
TROUBLESHOOTING PERFORMANCE
PROBLEMS
The lists below indicate possible areas to check when
air or sound values do not match expectations. Most fan
problems can be pinpointed to one of these common
causes.
Air Capacity Problems:
1. Resistance of system not at design rating. If resistance
is lower than expected, both airflow and horsepower
may be up. If resistance is higher than anticipated, air
volume will be down.
2. Fan speed is not at design speed.
3. Air density not at design values. Also check air perfor-
mance measurement techniques/procedures.
4. Devices for air modulation are closed or plugged. Also
check filters.
5. Wheel mounted improperly or is rotating in reverse.
6. Parts of system or fan have been damaged or need
cleaning.
Noise Problems:
1. Air performance is incorrect and fan is not at design
point of operation. Fan forced to operate in an unstable
flow region.