Environmental Corrosiveness Classification

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1、CombinationCorrosionCouponTestingNeededforTodaysControlEquipmentAccuratereliabilityanalysesforelectronic/electricaldevicesinpulpandpapermillsrequiresilverandgoldcouponsinadditiontocopperC.O.MullerPurafil,Inc.2654WeaverWayDoraville,Georgia30340INTRODUCTIONCopper,silver,andgoldareimp

2、ortantfunctionalmaterialsfoundinmanyoftheelectrical/electronicdevicesinuseintoday'spulpandpapermillcontrolrooms.Thereliabilityofthesedevicesmaybegreatlyaffectedbythepresenceofcorrosivegasesinthelocalenvironment.Eventracelevelsofthesegasescancausefailuresduetotheformationofcorrosion

3、productsinandonthecircuitryandconnectorsofthesedevices.Andduetothenatureoftheprocessesinvolvedinpapermanufacturing,itisalmostacertaintythatthesedeviceswillatsometimebeexposedtocorrosivegases.Atmosphericcorrosionofcopperhasbeenstudiedextensivelyandtestshavebeendevisedtomeasuretherat

4、esofcoppercorrosion.Thesecorrosionratesarecurrentlybeingusedtogaugeelectrical/electronicequipmentreliability.Thehighertherateofcoppercorrosion,thehighertheprobabilityofequipmentdamageand/orfailure(duetocorrosion).StudiesofbothlaboratoryandfielddatacollectedbyPurafil,Inc.hasshowntha

5、tusingcoppercorrosionaloneasagaugeforequipmentreliabilitycanseriouslyunderstatethecorrosivepotentialofthelocalenvironment.Examinationofbothsilverandgoldcorrosiondatahaveshowninstancesofanenvironmentwhichisnoncorrosivetocopperbeingextremelycorrosivetosilverand/orgold.Itisbecauseofre

6、sultssuchasthesethatanytestingwhichattemptstopredictelectrical/electronicequipmentreliabilityshouldincorporatecopper,silver,andgoldcorrosionasdeterminants.CURRENTSTANDARDSANDMETHODOLOGIES1TheInstrumentSocietyofAmerica(ISA)publishedastandardwithwhichtoclassifyairbornecontaminantstha

7、tmayaffectprocessmeasurementandcontrolsystems.Thispresentedthemanufacturersandusersofelectrical/electronicdevicesawaytopredictthereliabilityofthosedevicesexposedtocorrosivegases.Onemethodinvolvestheuseofspeciallypreparedcoppercoupons.Thesecouponsareplacedinthelocaloperatingenvironm

8、entforaperiodoftime,usuall