Twin City Modular Plenum Fans - MPLFN / MPLFS / MPLQN / MPLQS - IM-495 - Manual (Page 5)

Twin City IM-495 5
Wheel and Shaft Maintenance
Periodically.inspect.the.shaft.and.wheel.for.dirt.buildup,.
corrosion,.and.signs.of.excess.stress.or.fatigue..Clean.
the.components.and,.when.appropriate,.apply.new.coat-
ings.. (Any. addition. of. coatings. or. weld. can. create. an.
imbalance.).Check.the.balance.of.the.assembly.
Structural Maintenance
All.structural.components.or.devices.used.to.support.or.
attach.the.fan.to.a.structure.should.be.checked.at.regu-
lar.intervals..Vibration.isolators,.bolts,.foundations,.etc.,.
are.subject.to.failure.from.corrosion,.erosion,.and.other.
causes..Improper.mounting.can.lead.to.poor.operation.
characteristics.or.fan.fatigue.and.failure.
Check. metallic. components. for. corrosion,. cracks,. or.
other. signs. of. stress.. Concrete. should. be. checked. to.
ensure.the.structural.integrity.of.the.foundation.
Troubleshooting Guidelines
Use. current. safety. practices. when. investigating. fan. or.
system. performance. problems.. General. safe. practices.
and. performance. troubleshooting. guidelines. can. be.
found.in.AMCA.Publications.410.and.202,.respectively..
Fan. application.and. field.measurement.procedures.can.
be.found.in.AMCA.Publications.201.and.203.
Troubleshooting Performance Problems
The.lists.below.indicate.possible.areas.to.check.when.air.
or.sound.values.do.not.match.expectations..Most.fan.prob-
lems.can.be.pinpointed.to.one.of.these.common.causes.
Air Capacity Problems:
1..Resistance. of. system. not. at. design. rating.. If. resis-
tance. is. lower. than. expected,. both. airflow. and.
horsepower. may. be. up.. If. resistance. is. higher. than.
anticipated,.air.volume.will.be.down.
2..Fan.speed.is.not.at.design.speed.
3..Air.density.not.at.design.values..Also.check.air.per-
formance.measurement.techniques/procedures.
4..Devices. for. air. modulation. are. closed. or. plugged..
Also.check.filters.
5..Wheel.mounted.improperly.or.is.rotating.in.reverse..
6..Parts.of.system.or.fan.have.been.damaged.or.need.
cleaning.
Noise Problems:
1..Air.performance.is.incorrect.and.fan.is.not.at.design.
point. of. operation.. Fan. forced. to. operate. in. an.
unstable.flow.region.
2..Bearing.failure..Check.bearings.(lubrication).
3..Supply.voltage.high.or.inconsistent.supply.frequency..
Adjustable. frequency. controllers. can. generate. motor.
noise.
4..Objects. which. are. installed. in. a. high. velocity. air-
stream. can. generate. noise.. This. includes. flow. sen-
sors,.turning.vanes,.etc.
5..Poor.fan.inlet.conditions.
6..Acoustics.or.sound.measurement.procedure.incorrect.
Vibration Problems:
1..Misalignment.of.drive.components.
2..Poor.foundations.or.mounting.structure.(resonances).
3..Foreign.material.attached.to.rotating.components.
4..Damaged. rotating. components. (bearings,. shaft,. fan,.
wheel).
5..Broken,.loose.or.missing.setscrews.
6..Loose.bolts..
7..Vibration.transmitted.by.another.source.
8..Water.accumulating.in.airfoil.blades.
9..Fan.is.operating.in.stall.or.unstable.flow.region.
NOTE:. All. fans. manufactured. by. Twin. City. Fan. &.
Blower.are.factory.balanced.prior.to.shipment..Handling.
and. movement. of. the. fan. during. shipment. may. cause.
the. rotating. assembly. to. shift.. Balance. should. be.
checked.once.the.fan.is.installed..If.a.final.trim.balance.
is.required,.it.is.the.end.user's.responsibility.to.bring.the.
fan.back.to.factory.specifications..Final.trim.balancing.is.
not.the.responsibility.of.Twin.City.Fan.&.Blower.
Motor Problems:
1..Incorrect.wiring.
2..Speed.of.fan.too.high.
3..Parts.improperly.installed.-.binding.
4..Bearings.improperly.lubricated.
5..WR
2 .capability.of.motor.too.low.for.application.
6..Protection.devices.may.be.improperly.sized.
Motor Lubrication.–.The.major.cause.of.motor.bearing.
failure.is.contamination.of.grease,.insufficient.grease,.or.
incompatibility. of. grease.. If. a. fan. is. to. be. stored. for.
any.length.of.time.at.the.job.site.and.the.bearings.are.
regreasable,. the. motor. bearings. should. immediately. be.
filled. with. grease. while. rotating. the. fan. and. then. the.
bearings.should.be.regreased.and.rotated.monthly..This.
will.prevent.moisture,.which.condenses.within.the.bear-
ing,.from.corroding.the.raceways..Most.greases.used.on.
motor.bearings.are.lithium.base..Use.the.greases.shown.
in.the.motor.information..Do.not.mix.the.bases.without.
completely.purging.out.the.initial.grease.
Initially,. follow. the. lubrication. instruction. in. the. motor.
information.. The. frequency. of. lubrication. should. be.
adjusted.depending.on.the.condition.of.the.old.grease.
being. purged.. This. is. the. responsibility. of. the. user.. If.
the.grease.is.dirty,.the.lubrication.frequency.should.be.
more.often.
a..Noise. –. If. a. bearing. is. increasing. in. noise. intensity.
and/or.vibration,.it.will.probably.result.in.failure.
b..Temperature. –. If. a. bearing. temperature. begins. to.
gradually. rise,. it. will. generally. result. in. failure.. A.
bearing.can.operate.up.to.200.degrees.and.operate.
satisfactorily.if.the.temperature.remains.constant.and.
the.bearing.receives.adequate.lubrication..Remember.
that.a.roller.bearing.under.the.same.load.and.speed.
will.be.somewhat.more.noisy.and.run.warmer.than.a.
ball.bearing..This.is.normal.
Rough.handling.and/or.dropping.a.fan.can.result.in.bri-
nelling.the.bearing..This.appears.as.a.clicking.noise.at.
first,.then.gradually.worsens.until.failure.