Aerovent IM-391 - Manual (Page 6)

6 Aerovent IM-391
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.
Recheck 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 ini-
tial 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. Aerovent recommends
final balancing of the unit after the drive components
are installed. Failure to do so may void the warranty.
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.
2. Bearing failure. Check bearings (lubrication).
3. Supply voltage high or inconsistent supply frequency.
Adjustable frequency controllers can generate motor
noise.
4. Objects which are installed in a high velocity airstream
can generate noise. This includes flow sensors, turning
vanes, etc.
5. Poor fan inlet conditions.
6. Acoustics or sound measurement procedure incorrect.
Vibration Problems:
1. Misalignment of drive components.
2. Poor foundations or mounting structure (resonances).
3. Foreign material attached to rotating components.
4. Damaged rotating components (bearings, shaft, fan,
wheel, sheaves).
5. Broken, loose or missing setscrews.
6. Loose bolts.
7. Vibration transmitted by another source.
8. Water accumulating in airfoil blades.
9. Fan is operating in stall or unstable flow region.
NOTE: All fans manufactured by Aerovent are factory bal-
anced prior to shipment. Handling and movement of the
fan during shipment may cause the rotating assembly to
shift. Balance should be checked once the fan is installed.
If a final trim balance is required, it is the end user’s re-
sponsibility to bring the fan back to factory specifications.
Final trim balancing is not the responsibility of Aerovent.
Refer to Figure 8 for vibration guidelines.
Motor Problems:
1. Incorrect wiring.
2. Speed of fan too high.
3. Parts improperly installed - binding.
4. Bearings improperly lubricated.
5. WR2 capability of motor too low for application.
6. Protection devices may be improperly sized.
Drive Problems:
1. Belts improperly tensioned.
2. Drive alignment is poor.
Condition
Fan
Application
Category
Rigidly Mounted
mm/s (in./s)
Flexibly Mounted
mm/s (in./s)
Start-up
BV-3 6.4 (0.25) 8.8 (0.35)
BV-4 4.1 (0.16) 6.4 (0.25)
Alarm
BV-3 10.2 (0.40) 16.5 (0.65)
BV-4 6.4 (0.25) 10.2 (0.40)
Shutdown
BV-3 12.7 (0.50) 17.8 (0.70)
BV-4 10.2 (0.40) 15.2 (0.60)
Figure 8. Vibration Guidelines, unfiltered
Value shown are peak velocity, mm/s (inches/s), Filter out.
Table taken from ANSI/AMCA Standard 204-05, Table 6.3.
AMCA defines BV-3 for applications up to 400 HP; BV-4 for applications
over 400 HP.