Twin City Centrifugal Fans - ES-52 - Manual (Page 7)

Twin City Engineering Supplement ES-52 7
bearings.with.split.pillow.block.housings..Observation.of.
the. condition. of. the. grease. expelled. from. unit. ball. or.
roller. bearings. at. the. time. of. relubrication. is. the. best.
guide.as.to.whether.regreasing.intervals.and.the.amount.
of.grease.added.should.be.altered..This.observation.is.
particularly.important.when.bearings.operate.continuous-
ly.over.160°F..Spherical.roller.bearings.with.split.pillow.
block.housing.should.be.lubricated.until.grease.purges.
or.overheating.may.result..Follow.the.lubrication.interval.
and.amount.noted.in.Figure.11..Spherical.roller.bearings.
with.split.pillow.block.housings.should.be.serviced.once.
per.year..Remove.cap,.clean.out.old.grease.and.replace,.
filling.the.bottom.half.of.the.housing.1/3.full.
. Greases. are. made. with. different. bases.. There. are.
synthetic.base.greases,.lithium.base,.sodium.base,.etc..
Avoid.mixing.greases.with.different.bases..They.could.be.
incompatible.and.result.in.rapid.deterioration.or.break-
down.of.the.grease.
. All.bearings.are.filled.with.grease.before.leaving.the.
factory.. When. the. fans. are. started,. the. bearings. may.
discharge. excess. grease. through. the. seals. for. a. short.
period. of. time.. Do. not. replace. the. initial. discharge.
because.leakage.will.cease.when.the.excess.grease.has.
worked.out..Sometimes.the.bearing.has.a.tendency.to.
run. hotter. during. this. period. and. one. should. not. get.
alarmed. unless. it. lasts. over. 48. hours. or. gets. above.
220ºF.. When. relubricating,. use. a. sufficient. amount. of.
grease.to.purge.the.seals..Rotate.bearings.during.relu-
brication.where.good.safety.practice.permits.
. For.bearings.with.oil.lubrication,.sight.gauges.are.installed.
so. that. a. proper. level. can. be. reviewed. and. maintained..
Sight.gauges.should.be.read.with.bearings.not.rotating.
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,.sheaves).
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..Refer.
to.Figure.12.for.vibration.guidelines.
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.
Drive Problems:
1..Belts.improperly.tensioned.
2..Drive.alignment.is.poor.
Condition
Fan
Application
Category
Rigidly Mounted
mm/s (in./s)
Flexibly Mounted
mm/s (in./s)
Start-up
BV-3 6.4.(0.25) 8.8.(0.35)
BV-4 4.1.(0.16) 6.4.(0.25)
Alarm
BV-3 10.2.(0.40) 16.5.(0.65)
BV-4 6.4.(0.25) 10.2.(0.40)
Shutdown
BV-3 12.7.(0.50) 17.8.(0.70)
BV-4 10.2.(0.40) 15.2.(0.60)
Figure 12. Vibration Guidelines
Value.shown.are.peak.velocity,.mm/s.(inches/s),.Filter.out.
Table.taken.from.ANSI/AMCA.Standard.204-05,.Table.6.3..
AMCA.defines.BV-3.for.applications.up.to.400.HP;.BV-4.for.applica-
tions.over.400.HP.