Aerovent IM-201 - Manual (Page 5)

Aerovent IM-201 5
4. Install push rod and tighten ball joint.
5. Adjust limit switches per Section 3.2.1.3.
3.2.1.5 Actuator Pitch Adjustment
The maximum and minimum blade pitch is mechanically
set in the rotor. The limit switches in the actuator can be reset
to reduce the range between these limits to provide different
maximum and minimum airflows. This may be done as follows:
1. Remove terminal box and/or end covers from actuator as
required.
2. Energize terminals, according to the owner's manual, with
120 VAC to drive the blades to minimum pitch.
3. Start the fan and energize the proper terminals, accord-
ing to the owner's manual, to increase the pitch until the
desired maximum airflow is obtained.
4. Adjust limit switch (LS1), according to the owner's man-
ual, to open at this position. This will stop the motor at
the new maximum pitch position.
5. Energize terminals, according to the owner's manual, to
decrease the pitch until the desired minimum airflow is
obtained.
6. Adjust limit switch (LS2), according to the owner's man-
ual, to open at this position. The motor will stop at the
new minimum pitch position.
7. Check limit switch adjustment by driving motor through
range.
8. Replace terminal box and/or end covers as required.
3.2.2 FPMC Fan, Handwheel Version
An external handwheel on the vane section is con-
nected to a miniature wormgear jack inside the core of the
vane section. This in turn is connected to the hub cover of
the rotor. If the handwheel is installed on the right side of
the fan, looking in the direction of airflow, counterclockwise
rotation of the wheel will increase blade pitch. If installed on
the left side, clockwise rotation will increase pitch. With this
arrangement the blade pitch can be changed while the fan is
running.
3.2.3 FPMC Fan, Quadrant
With this version of the FPMC, the external linkage to
the rotor is clamped in one position by a handwheel on a fixed
bolt. The blade forces are such that the fan must be turned off
to adjust the blade pitch. Move the lever upstream to decrease
pitch, downstream to increase it.
3.3 AXICO FPDA FAN
The FPDA fan is an adjustable pitch fan. The blade
pitch has been factory set to meet the airflow requirement of
the job specification. The blade pitch may be changed to meet
other airflow requirements. The hub fairing is marked with
degree marks at the leading edge of the fan blade The first
mark near the inlet side of the fairing is 60°. The last mark
near the center of the fairing is 25°. The intermediate marks
are in 5° increments. The marks are referenced to the center
of the leading edge of the fan blade.
3.3.1 Blade Pitch Adjustment
To set the blade pitch proceed as follows:
NOTE: An 8 mm key with a square drive adaptor fitted
to a torque wrench is required.
1. Remove the stator section access panel per steps 1 through
5 of Section 5.7 to gain access to the fan blades on
Arrangement 4 Type 2 fans. Access on other fans may be
gained by removal of the protective inlet screen if desired.
2. Loosen the four M12 blade bolts until the blade is free to
rotate.
3. Rotate the blade to align the center of the leading edge with
the desired pitch mark.
CAUTION: Do not exceed 55° blade pitch without consult-
ing factory.
4. Alternately tighten opposite blade bolts to 40 ft-lb.
CAUTION: It is important that the bolts are torqued to the
specified value. Do not hand-tighten the bolts.
5. Repeat Steps 2 through 4 for all blades.
6. Replace stator section access panel or inlet screen.
CAUTION: The motor current should be checked not to
exceed the nameplate rating when blade pitch has been
increased.
4.0 INSTRUMENTATION (PITCH
CONTROL) AXICO FANS
4.1 GENERAL
Various parameters such as pressure, temperature, gas
concentration, relative humidity, or velocity can be measured
to provide the required system airflow. The sensor is connect-
ed to a controller which provides an electrical or pneumatic
control signal to the fan. The fan pitch is modulated to meet
the system airflow set point requirement.
4.2 FPAC FAN
The FPAC AXICO fan is factory adjusted to go from
minimum to maximum pitch with a 3 to 15 psig pneumatic
control signal. Two-position or multi-position pitch settings
may be obtained with intermediate control pressures. The
blade pitch may also be manually controlled by supplying the
control pressure from a pressure regulator.
4.3 FPMC FAN
The FPMC fan actuator is adjusted at the factory to go
from minimum and maximum pitch with limit switches at the
ends of the stroke. The limit switch settings may be changed
to reduce the range of blade pitch for two-position step
control from contact closure. See Figure 3 for typical wiring
diagram.
4.4 PARALLEL FAN OPERATION
When two or more fans are installed to operate in par-
allel, two problems are commonly experienced.
1. When less than all the fans are in operation, air circulates
backwards through the fan that is shut down, causing it to
freewheel backwards. This can be very damaging to the
motor when the fan is restarted.
2. When all fans are running together, they may not be com-
pletely stable.
SOLUTION: The signal to all fans must be a common
signal, and it should be a heavily damped signal so the changes
of blade angle occur very slowly. Also the fans must have their
positioners calibrated so that all positioner arms are at the
same angle for a given control pressure. A second check can
be made to insure that motor amps match within 5% at a given
signal pressure.
NOTE: STARTING A FAN WHILE THE ROTOR
ASSEMBLY IS WINDMILLING BACKWARDS VOIDS
ALL MOTOR AND FAN WARRANTIES.