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MKB June 18, 2008 Page 4 of 12
ANOTEABOUTVOLTAGE
Inpreviousyears,peopledesiringtomeasureresistivityorresistancefollowedtheASTMD264,
ASTM991,NFPA56AorNFPA99teststandards.Theseproceduresrequiredpeopletotestat
either500or1000volts.Thiscausedconcernregardingsafetytothepersondoingthetests.The
ESDAstandardizedthetestproceduressothatlowervoltscouldbeusedatspecificranges.
TheACL800meterusesa9voltbattery.Somemeterswith9voltsbatteriesdonotgivethe
accuracythatyouneedtoperformthetestsespeciallyatvalueshigherthan107.TheACL800is
builtwithatransformerthatconvertsthe9voltchargefromthebatteryto10voltsor100volts
(whichevervalueisselected).Themeterappliesaconstantchargeoverthecompletevoltage
range.Accuracyisdependsonappliedvoltage,temperature,andhumidity.
TEMPERATUREANDHUMIDITY
Thehumidityandtemperatureaffecttheelectricalpropertiesofthematerialbeingtested.The
combinationoflowhumidityandlowtemperaturewillgivethehighestelectricalresistance
resultsorslowestdissipationtimes.Athighhumidityathinlayerofwateriscondensedor
absorbedonorinthematerialbeingtested.Thisistrueofhydroscopicadditivesthatareadded
toamaterialtoincreasetheelectricalconductivity.Theseadditiveswillallowmoisturetobe
absorbableinthematerialstheyareaddedto.
Atelevatedtemperaturesthemobilityoffreeelectronsisincreasedtherebyincreasingthe
materialsconductivity.Thisisespeciallytrueforcarbonblack,metallicoxides,metals,andother
materialsaddedtoamaterial.Whenthematerialisatalowertemperature,builtinstresses
occurwhichmightincreasetheresistanceduetoincreaseddistancebetweentheconductive
additives.Thus,humidityandtemperaturemustbeknown.
RECORDINGDATA
ANSI/ESDAssociationandEuropeanCECCrecognizetheenvironmentaleffectstotest
measurementsandspecifyintheirstandardsthattheymeasuredandrecorded.Itispossibleto
testormanufactureamaterialathighhumidityandpassallthetestspecifications,butwhen
thecustomerreceivesthematerialandusesitatalowerhumidityortemperaturethematerial
failstopassthespecifications.Thiscancauserejectsandlossofproduct.
BothESDS4.1ESDProtectiveWorksurface
section6.2.4andESDS7.1‐1994ResistiveCharacterizationofMaterialsFloorMaterialssections
5.2.4and5.3.3requirereportingoftemperatureandhumidityatthetimeoftesting.
ANSI/EOS/ESD‐S11.11‐1993SurfaceresistancemeasurementofStaticDissipativePlanar
Materialssection11.0Bstates,“reporttheconditioningperiod,relativehumidity,and
temperature.”
CALIBRATION
Calibrationisrecommendedannually.TheACL800metercomeswithaNISTcertificatewhen
ordered.AfteroneyearthemeterscanbesentbacktoACLInc.foranewNISTcertificatefora
labfeeoritcanbesenttoacertifiedcalibrationlab(Seepage11forinstructions).Themeters
alsocomewithaCEmarkapproval.