IMI-CPP - page 2

BULLETIN IMI-CPP
JUNE 2011
PAGE2
VAWVARIABLEAIRVOLUMEFANSDesign 47
Bulletin IMI-CPP6/2011
A. DESCRIPTIONOFEQUIPMENT
General
ChicagoBlower CorporationControllablePitchPneumatic (CPP) fansare high
performance, variablepitch, vanaxial fans. They are quality productswhich, with proper
care, will providemany years of satisfactory operation.
CPP fanwheelshave cast aluminum hubsand cast aluminum airfoil blades. CPPwheels
aremounted on themotor shaftsby useof straight boreadaptor bushings.
Fan casingsare steel, formedwith integrally formed inlet and outlet flanges. Casingsare
completewithwelded steel guide vanes, andwelded steel inner fairing rings. Steelmotor
mounting bulkheadsarewelded to the inner fairing ringsand are recessed to accept
NEMA, "C" face flange, TEAO electricmotors.
ControllablePitchOperation
CAUTION:
Bladepitch changesaremadewhile the fan is running. To check blade
settings, stop fan, lock out switch. Bladepositionveneers are stamped at
each hub blade socket and each bladehasa cast-in position pointer to
indicate itspitch setting on thehub veneers.
CAUTION:
Blade settingsgreater than those stamped on fan nameplates (located
on fan casing)may overload themotors.
CPP centermounted pitch changingmechanismsaremated to fanwheels
through the same straight bore adaptor bushingsused tomount fanwheels to
motor shafts.
Thepitch changingmechanism consistsof an internallymounted pneumatic
actuator with spring return, connected to individual blade crankarms. Air is
supplied to theactuator through a rotating union from an externallymounted
pilot positioner, completewith a cable connected feedback.
ElectricOption
TheElectric option includesan electric/pneumatic transducer, for translation of
user electric signals to thepneumatic signals requiredby theexternal pilot
positioner.
Compressed air for theElectricoption is furnished either by theuser or by the
auxiliary pneumaticpower pressure system available fromChicagoBlower
Corporation. Theauxiliary system consisting of an air compressor, receiver,
gauges, filters drains, and air lines, ismounted to the fan casing or furnished loose
for usermounting.
In thisbulletin, information specific to theElectric optionwill generally appear
near theend of itsappropriate section, accentuated by thephrase "Electric
Option".
NOTE:
Please refer to the individual rotating union and pilot positioner safety,
installation, operating andmaintenance instructions, furnished by theirmanufacturers and
providedwith the fan, for detailson those items.
1 3,4,5,6,7,8,9,10,11
Powered by FlippingBook