BAC 3872C - Extended Shutdown

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6
After 24 hours of operation
under thermal load, perform the
following services:
9
Check the tower for any
unusual noise or vibrations.
9
Check the operating water
level in the hot and cold water
basins.
9
Adjust the make-up valve if
necessary.
9
Check the belt tension and
readjust if necessary.
9
Inspect the spray nozzles and
heat transfer section.
• Adjustthevalve(suppliedbyothers)inthetowerbleedlinetoachievethedesired
bleedratebyclosingoropeningthevalve.
• Inspectthenozzlesandheattransfersectionasdescribedin“WaterDistribution
System”onpage 19 (Figure 6).
• Executeoneofthefollowingbiocidetreatmentprogramswhileoperatingthe
circulatingpumpandpriortooperatingtheunitfans:
– Resumetreatmentwiththebiocidethatwasusedpriortoshutdown.Operatethe
pumponlywhilemaintainingthemaximumrecommendedbiocideresidualfora
sufcientduration(residualandtimewillvarywiththebiocide)asrecommended
bythewatertreatmentsupplier.Startthefanonlyafterthistreatmentperiodis
completed.
– CheckthepHofthecirculatingwaterand,ifnecessary,adjustitto7.0-7.6pH.
Then,runningthepumponly,treatthesystemwithsodiumhypochloritetomaintain
alevelof4to5mg/l(ppm)freechlorine(asCl
2
)overasixhourperiod.Testkitsfor
measuringthefreeresidualofchlorinearecommerciallyavailable.Startthefanonly
afterthistreatmentperiodiscompleted.
• Forunitswiththeoptionalgeardrivesystem,seepage 13forinitialstart-up.
• Forinitialstart-up,brieyenergizethefanmotor(s)andnotethedirectionofrotation.
Thefanshouldrotateinthedirectionindicatedbythearrowonthefancowl.
• Runthefaninmanualmodeforseveralminutestocheckforanyunusualnoiseor
vibrations.
• FortheBALTIGUARD™FanSystem,BALTIGUARDPLUS™FanSystemor2-speed
motors:checkthatthestarterincorporatesa15secondtimedelaywhenswitching
fromhightolowspeed.
• Checktheoperationofthevibrationcutoutswitch(seepage 32).
• Oncethecoolingtowerisoperating,checkthecurrentandvoltageofallthreephases
(legs)ofthefanmotorwithaheatloadonthetowerunderwarmambientconditions.
Thecurrentmustnotexceedthemotornameplaterating.
• ForunitswithVFDs,seepage 35.
• ForunitswiththeoptionalElectricWaterLevelControl,seepage 20.
Extended Shutdown
Perform the following services whenever the unit is shutdown in excess of three days:
• Iftheunitismountedonvibrationisolatorsorisolationrails(byothers),refertothe
manufacturer’sguidelinesbeforeloading/unloadingweightfromtheunit.
• Disconnect,lock-out,andtag-outallfansandpumps.
• Closetheshut-offvalveinthemake-upwaterline(suppliedbyothers)anddraincold
waterbasinandallexposedwaterpiping.Heattraceandinsulateallexposedpiping.
• Tominimizetheriskofbiologicalcontaminationduringshutdown,itisrecommended
theentiresystembedrained.
• Cleanalldebris,suchasleavesanddirt,fromtheinteriorandexterioroftheunit,
includingthelouversortheoptionalcombinedinletshields.
• Cleanandushthecoldwaterbasinwiththebasinstrainerinplace.
• Leavethecoldwaterbasindrainopensorainandmeltingsnowwilldrainfromthe
unit.
ATTENTION: Check to ensure the
controls for the fan motor are set
to allow a maximum of six on-off
cycles per hour to prevent motor
overload.
DANGER: Do not perform any service
on or near the fans, motors, and
drives, or inside the unit without
first ensuring that the fans and
pumps are disconnected, locked
out, and tagged out.