EngA AF Series

A
AF / DCU MANUAL
IOM-52 16 of 23 Apr 13 R2
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LEAKCHECKING
Afterinstallation,alljoints,bothfactoryandfieldinstalled,shallbepressurecheckedandleaktestedusing
approvedindustrymethods.
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WARNING:

Testpressuresmustnotexceedthemaximumpressureratingsspecifiedontheunit
ratingplate.
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WARNING:

OxygenmustNEVERbeusedtopressurizeasystem.
Ensureallservicevalvesandmanualvalvesareopen.Ifleaksarelocated,removepressureandrepair
leaks.Recheckasnecessary.
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Ifbrazingisnecessarytorepairleaks,adrynitrogenpurgethroughtubingwhilebrazingisrequiredto
preventtheformationofcopperoxides.
EVACUATIONANDDEHYDRATION
Thesystemmustbeevacuatedpriortocharging.Properevacuationwillremovenon‐condensablegasses
andwatervaporfromthesystem.Watervaporinthesystemwillcombinewiththeoilandrefrigerantto
formacidsandotherundesirableby‐products.Non‐condensablegassessuchasairornitrogenwill
increasetheheadpressureandoperatingtemperatureanddegradesystemperformance.
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Sketchapipingschematicshowingallvalvesandcomponents.Checkthediagramtoensurethatall
portionsofthesystemwillbeevacuated.Addadditionalhosesorservicefittingsasrequired.
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Note:

Ahighvacuumcannotbepulledthroughasolenoidvalvewhetherornotitisenergized.
Ahighvacuumcannotbepulledthroughacheckvalveregardlessofdirectionofflow.
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EvacuationProcedure:
1. Removeleak‐testinggassesfromthesystem.Ifrefrigerantwasusedtoleaktest,therefrigerant
shallberecovered.
2. Connectahighvacuumpumptothesystem.Usetheshortestandlargestdiameterhoseavailable.
3. Useasmanyconnectionsasthesystemwillallow.
4. Ifevacuatingthrough‘Schraedervalves’,removetheSchraedervalvecorebeforeevacuation.
5. Openallservicevalves.
6. Useamicrongaugetomeasurethevacuum.
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Note:

Astandardrefrigerationgaugewith“inchesofmercury”isnotsuitabletomeasurethehigh
vacuums.AhighvacuumgaugecapableofmeasuringMicronsisrequired.