IMI-CPP - page 5

BULLETIN IMI-CPP
JUNE 2011
PAGE5
fansandmotors are capableof across-the-line starts, however reduced voltage
startingmaybe required by local conditionsor limitations.
Actuator
Theactuators require eightyPSIG supply air. Thepilot positioners accept three-to
fifteenPSIG control air.
Calibrationof Pilot Positioner
A cable feedback isused from theactuators toposition them in accordancewith
control air signals. Before disconnecting the feedback cable, noteand record the
location of the cable clamp assemblyon thepilot positioner lever arm.Make sure
the clampassembly remains in that position during calibration.
NOTE:
Refer to thepilot positionermanufacturers installation instructions for
additional detail.
1. Remove thepilot positioner side cover. Align the scribemark on the cam plate
with the cam roller.
2. With theactuator atmid-stroke, the fanbladesat themid-point of theblade
setting range, and the scribemark aligned, pull the cable taut and tighten the
set screw in the cable clamp assembly. Check that the cablepasses through the
center of thehole in the fan casing.
3. Connect an air line from the rotating union to the 'SUPPLY' port in thepilot
positioner.
4. Block the "VALUE' port of thepositioner with a suitablepipeplug.
5. Connect a supply air line to theair filtermounted on thepositioner.
6. Connect a control air line to the "INSTR' port in thepilot positioner.
7. Apply ninePSIG to the 'INSTR' port. This should put the scribemark in line
with the cam roller. If it doesnot, turn the knurled spring adjustment nut
located to the left of the can roller.When the scribemark is in line, the
positioner is calibrated.
8. The instrument pressure range is from threePSIG to fifteenPSIG. Check that
theactuator and blade settingsare; at theirminimum positionat threePSIG; at
theirmid position at ninePSIG; and at theirmaximum positionat fifteen
PSIG. If they arenot, adjust the cable clamp on thepositioner lever arm.
9. Replace thepositioner side cover.
ElectricOption: Calibrationof Electric/PneumaticTransducer
1. Set pressure from source (i.e., CBC furnished compressor or user air) to
seventyPSIG. Adjustments can bemadeon filter regulator if orderedwith
fan. ChicagoBlower Corporation presets regulator at seventyPSIG.
2. In conjunctionwithpilot positioner calibration, removepipeplug from
transducer port and install a three-to-fifteenPSIG range, ¼NPT, pressure
gauge.
3. Apply a twelvemilliamp signal to transducer. This should correspond to a nine
PSIG air signal andmiddleblade setting. If it doesnot, change toa four
milliamp signal and zeroout transducer using adjustment screw located on side
of transducer, while reading pressure gaugeand blade setting (zero point is
threePSIG andminimum blade setting).
4. Apply a twentymilliamp signal and set span of operation using adjustment
screwnext to zero adjustment while readingpressure gaugeand blade setting
(a twentymilliamp signal will correspond to a fifteenPSIG air signal and
maximum blade setting).
5. Repeat steps threeand four asoften asnecessary.
6. If there isa largediscrepancy at the zero point then repeat calibration of pilot
positioner by applying a twelvemilliamp signal to transducer and adjust knurled
1,2,3,4 6,7,8,9,10,11
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