CENTRIFUGAL FANMAINTENANCE HANDBOOK1. GENERAL INSTRUCTION FOR FANS STARTING AND RUNNING1.1. CHECK BEFORE STARTINGThat all bolts have been normally tightenedAnchorage boltingBearing stands on baseMotor/baseBearing/standsBearing covers/housingsHub/shaft assemblyInlet cones/casingCasing/baseInlet boxes/casingCasing/casingDampers/casing inletsActuator/damperMiscellaneous boltingBearing lubrication controlOpen bearing housing and check quantity, quality and distribution of lubricant Running parameters of lubrication system (see specific instruction)Alignment controlRadial run outAxial run outFree rotation of impellerRadial clearance between impeller inlet and coneSealing device runs properlyHand rotation of complete rotor with driverConnectionsAxial deflection of flexibleRadial deflection of flexibleNo load on fan connexion flangesPage 1CENTRIFUGAL FANMAINTENANCE HANDBOOKGuards controlOn couplingsOn cooling diskOn shaft between bearingInlet protective screenOutlet protective screenFittingDamper or guide vane blades fitted for pre rotation of gas flow at impeller inletForeign objectsFan inner inspectionDucting inner inspectionProtection of plant before startingControl of conformity of electric connectionAuthorisation of field responsible for starting-upDamper or inlet guides vane closed for starting1.2. CHECK DURING STARTING PERIODRotation direction (see table 1)Table. 1Backward curvedBackwardForward backwardRadial vanesOpen radialbladeinclinedcurvedPage 2CENTRIFUGAL FANMAINTENANCE HANDBOOKVibrations and soundsFan bearing-coupling sideAxialVerticalHorizontalSoundFan bearing-opposite couplingAxialVerticalHorizontalSoundMotor bearing-coupling sideAxialVerticalHorizontalSoundMotor bearing-opposite couplingAxialVerticalHorizontalSoundBearing temperatureFan bearing-coupling side 15 mn after startingFan bearing-opposite coupling 15 mn after startingOil lubrication systemLevel checkingTemperature checkingFlow rate checkingShaft sealTemperaturePage 3CENTRIFUGAL FANMAINTENANCE HANDBOOKGas flow controlActuator power supplyVoltage/pressureActuator control supplyVoltage/pressureActuator control operation1.3. CHECK AFTER STARTINGRunning throughout the working rangeVibrationsSoundAmp.et max.flow (as per contract)Bearing temperature progressEvery quarter of one hour during one hourEvery hour during 6 hoursStuffing box temperaturePage 4CENTRIFUGAL FANMAINTENANCE HANDBOOK2. LIST OF COMMON TROUBLESTROUBLEPOSSIBLE ORIGINREMEDY2.1BearingA. LubricantexcessinA. Restore correctamountof lubricantoverheatingbearingscheck grease valve working (if any)B. ImproperqualityofB. Remove bearings and clean them uplubricantlubricate again with proper lubricantC. Lack oflubricantinC. Restore correct amount of lubricantbearingD. ToosmallradialD. Reset radial clearanceclearance in bearingsE. LoosenbeltdriveE. Tightenthebelts according to(slipping)manufacturer instructionsF. CoolingdisknotF. Fit cooling disk on shaftmountedG. Excessive temperature ofG. Check therunningconditionsrestoregascorrect gas temperatureH. AmbienttemperatureH. For every 150C increase in temperatureover 400Cof bearing, the lubrication intervalshould be reduced to half of specifiedvalue2.2AbnormalA. InsufficientorA. Checklubricationdevicesnoisesininadequate lubricationworking-restore correct amount ofbearingslubricantwhistlingB. Wearing of bearingsB. Replace the bearingssoundsC. ForeignobjectsinC. Remove,cleanupandcheckhammeringbearing housingbearings-change the bearings iforrumblingnecessary and lubricatesoundsinD. BearingdamagedatD. Change the bearingsbearinghousingmounting,printing,pickingorwearingofrolling elementsPage 5CENTRIFUGAL FANMAINTENANCE HANDBOOKTROUBLEPOSSIBLE ORIGINREMEDY2.3 Fan vibrationA. Dust deposite on bladeA. Clean up the impellerB. WearingstripsnatchingB. Checkwearing-stripandreplaceifoffnecessaryC. IrregularerosionofC. Rebalance or change the rotorcorrosion of impellerD. DeflexionofwheelorD. Eliminatecausesofshaftcausedbyoverheating-change the rotoroverheatingE. PoorbalancingofE. Make impeller balancingimpellerF. WrongalignmentofF. Reset alignments according to specialcoupling or belt drivesinstructionG. ImpropertighteningofG. Tightenthebeltsaccordingtobeltsmanufacturerinstruction-checkalignmentH. PoorbalancingorH.Check balancing and working conditionincorrectworkingofof driving machines-repair or changedriving machinesthem if necessaryI. PoorshimmingorI. Reset the shim-packing and anchoringanchoring of motor-fanaccording to instructionsJ.Looseboltingof bearingJ.Tighten assembly bolting at requiredassemblytorqueK.Improperanti-vibratingK.Replace improper pads with correctlypad mounting (resonance)selected onesLExcessive rotation speedL.Checkmotorspeedorbelt driveratio-make the necessary correctionM.SurgingM.Change gas flow setting until anacceptable vibration level is reachedPage 6CENTRIFUGAL FANMAINTENANCE HANDBOOKTROUBLEPOSSIBLE ORIGINREMEDY2.4AbnormalA. Foreign object in fanA. Inspect the fan-rotate the fan by handnoises in fanB. Internal frictionsB. Check clearance between wheel andinlet cone and between shaft andsealing device-rotate the fan by handC. External frictionsC. Checklocationandfixingofguards-rotate the fan by hand2.5PrematureA. Excessive vibrationsA. Check and correct the various causeswearingofof vibrationbearingsB. Improper lubricationB. Check and correct lubricationC. Fan excited by externalC. Machines or isolate the fan itselfvibration when stoppedD. ConservationoffanD. Take precautionnary measures requiredwhenstoppedwithoutby surrounding and working conditionsprecautionagainst(intermittent running, conservationorcorrosive agentsreheating when stopped, etc)2.6ImpossibleA. Locking of rotorA. Checkand rotationofthe fan andstartingorinvestigate for the locking causesexcessive starting(frictions, obstacles etc)timeB. LowvoltageatmotorB. Check the line voltage-Reinforce theconnexionsline if excessive lossesC. Motor releaseC. Check setting of security devicesD. Too low power rating ofD. Change the motormotorE. ImproperstartingE. Correct the starting equipmentprocessF. ExcessivepowerF. Make sure that flow control device areconsumptionwhenin close position when startingstartingPage 7CENTRIFUGAL FANMAINTENANCE HANDBOOKTROUBLEPOSSIBLE ORIGINREMEDY2.7 Deficiency inA. Excessive speedA. Checkmotorspeedorbeltdriveperformancesratio-make the necessary correctionB. Pressure drop lower thanB. Set the control devices so as to getexpected in duct workdesign gas flowC. Too low rotation speedC. Checkmotorspeedorbeltdrivesration-make the necessary correction.Tighten belts as requiredD. Poor duct work design atD. Correct the design and dimensionningfan inlet and outletof duct workE. Wrong rotation directionE. Reverse motor rotation directionF. WrongmountingofF. Reverse the direction of impeller onimpeller (double inlet)shaftG. ExcessiveclearanceG. Set clearances according to instructionsbetweenimpellerandinlet cone3.1 CLEANING AND BALANCINGDust deposites may occur in certain installations and these may cause unbalance of the fan impeller due to erosion or corrosion, thus gradually causing damage to the bearings.Under such conditions, periodic vibration checks are recommended to determine any changes in the condition of the fan.If necessary, the fan must be cleaned or rebalanced.Large quantities of dust deposits may also reduce the fan performance.Page 8CENTRIFUGAL FANMAINTENANCE HANDBOOK3.2VIBRATION SEVERITY RANGEFig 2RMS VELOCITYACTIONMm/s effective00.0004.40Good04.4007.10Check at regular intervals07.1011.20Check at regular intervals and balance at convenient ime11.2018.00Clean and rebalance18.00Shut down immediately11.20Alarm18.00Shut downPage 9