Centrifugal Inline Fans
7
®
IMPORTANT
The fan has been checked for mechanical noises at
the factory prior to shipment. If mechanical noise
should develop, suggested corrective actions are
offered in the Troubleshooting section.
IMPORTANT
Over-tightening will cause excessive bearing wear and
noise. Too little tension will cause slippage at start-up
and uneven wear.
IMPORTANT
Adjust (tighten) belt tension after the first 24-48 hours
of operation.
6. The adjustable motor pulley is factory set for the
RPM specified. Speed can be increased by closing
or decreased by opening the adjustable motor
sheave. Two groove variable pitch pulleys must be
adjusted an equal number of turns open or closed.
Any increase in speed represents a substantial
increase in the horsepower required by a unit. Motor
amperage should always be checked to avoid
serious damage to the motor when speed is varied.
Belt Span
Deflection =
Belt Span
64
Figure 11
Figure 10
NOTE: Identical fasteners on opposing side must
also be loosened.
R
Operation: SQ-M / BSQ-M
1. Before starting up or operating fan, check all
fasteners for tightness. In particular, check the
setscrews in wheel hub (and pulleys, if applicable).
2. While in the OFF position or before connecting the
fan to power, turn the fan wheel by hand to be sure
it is not striking the venturi or any obstacle.
3. Start the fan and shut it off immediately to check
rotation of the wheel with directional arrow in the
motor compartment, see Figure 8.
4. When the fan is started, observe the operation and
check for any unusual noises.
5. With the system in full operation and all ductwork
attached, measure current input to the motor and
compare with the nameplate rating to determine if
the motor is operating under safe load conditions.
6. Keep inlets and approaches to fan clean and free
from obstruction.
Inspection: SQ-M / BSQ-M
Inspection of the fan should be conducted at the
first 30 minute and 24 hour intervals of satisfactory
operation.
30 Minute Interval
Inspect bolts, setscrews and motor mounting bolts.
Adjust and tighten as necessary.
24 Hour Interval
Check all internal components. On BSQ-M unit only,
inspect belt alignment and tension. Adjust and tighten
as necessary.
Figure 9
CORRECT
WRONG
WRONG
WRONG
5.
For BSQ-M Fans:
Belt tension can be adjusted by
loosening four fasteners marked “R” on the drive
frame (see Figure 10). The motor plate slides on
the slotted adjusting arms. Belt tension should
be adjusted to allow 1/64 inch of deflection per
inch of belt span. For example, a 15 inch belt
span should have 15/64 inch (or about 1/4 inch)
of deflection with moderate thumb pressure at
mid-point between pulleys (see Figure 11). Over-
tightening will cause excessive bearing wear and
noise. Too little tension will cause slippage at
start-up and uneven wear.
