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Designation:C518–10StandardTestMethodforSteady-StateThermalTransmissionPropertiesbyMeansoftheHeatFlowMeterApparatus1ThisstandardisissuedunderthefixeddesignationC518;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheDepartmentofDefense.1.Scope1.1Thistestmethodcoversthemeasurementofsteadystatethermaltransmissionthroughflatslabspecimensusingaheatflowmeterapparatus.1.2Theheatflowmeterapparatusisusedwidelybecauseitisrelativelysimpleinconcept,rapid,andapplicabletoawiderangeoftestspecimens.Theprecisionandbiasoftheheatflowmeterapparatuscanbeexcellentprovidedcalibrationiscarriedoutwithintherangeofheatflowsexpected.Thismeanscalibrationshallbecarriedoutwithsimilartypesofmaterials,ofsimilarthermalconductances,atsimilarthicknesses,meantemperatures,andtemperaturegradients,asexpectedforthetestspecimens.1.3Thisacomparative,orsecondary,methodofmeasure-mentsincespecimensofknownthermaltransmissionproper-tiesshallbeusedtocalibratetheapparatus.Propertiesofthecalibrationspecimensmustbetraceabletoanabsolutemea-surementmethod.Thecalibrationspecimensshouldbeob-tainedfromarecognizednationalstandardslaboratory.1.4Theheatflowmeterapparatusestablishessteadystateone-dimensionalheatfluxthroughatestspecimenbetweentwoparallelplatesatconstantbutdifferenttemperatures.Byappropriatecalibrationoftheheatfluxtransducer(s)withcalibrationstandardsandbymeasurementoftheplatetempera-turesandplateseparation.Fourier’slawofheatconductionisusedtocalculatethermalconductivity,andthermalresistivityorthermalresistanceandthermalconductance.1.5ThistestmethodshallbeusedinconjunctionwithPracticeC1045.Manyadvanceshavebeenmadeinthermaltechnology,bothinmeasurementtechniquesandinimprovedunderstandingoftheprinciplesofheatflowthroughmaterials.Theseadvanceshavepromptedrevisionsintheconceptualapproachestothemeasurementofthethermaltransmissionproperties(1-4).2Allusersofthistestmethodshouldbeawareoftheseconcepts.1.6Thistestmethodisapplicabletothemeasurementofthermaltransmissionthroughawiderangeofspecimenprop-ertiesandenvironmentalconditions.Themethodhasbeenusedatambientconditionsof10to40°Cwiththicknessesuptoapproximately250mm,andwithplatetemperaturesfrom–195°Cto540°Cat25-mmthickness(5,6).1.7Thistestmethodmaybeusedtocharacterizematerialproperties,whichmayormaynotberepresentativeofactualconditionsofuse.Othertestmethods,suchasTestMethodsC236orC976shouldbeusedifneeded.1.8Tomeettherequirementsofthistestmethodthethermalresistanceofthetestspecimenshallbegreaterthan0.10m2·K/Winthedirectionoftheheatflowandedgeheatlossesshallbecontrolled,usingedgeinsulation,oraguardheater,orboth.1.9Itisnotpracticalinatestmethodofthistypetotrytoestablishdetailsofconstructionandprocedurestocoverallcontingenciesthatmightofferdifficultiestoapersonwithoutpertinenttechnicalknowledge.Thususersofthistestmethodshallhavesufficientknowledgetosatisfactorilyfulfilltheirneeds.Forexample,knowledgeofheattransferprinciples,lowlevelelectricalmeasurements,andgeneraltestproceduresisrequired.1.10TheuserofthismethodmustbefamiliarwithandunderstandtheAnnex.TheAnnexiscriticallyimportantinaddressingequipmentdesignanderroranalysis.1.11Standardizationofthistestmethodisnotintendedtorestrictinanywaythefuturedevelopmentofimprovedornewmethodsorproceduresbyresearchworkers.1.12Sincethedesignofaheatflowmeterapparatusisnotasimplematter,aprocedureforprovingtheperformanceofanapparatusisgiveninAppendixX3.1ThistestmethodisunderthejurisdictionofASTMCommitteeC16onThermalInsulationandisthedirectresponsibilityofSubcommitteeC16.30onThermalMeasurement.CurrenteditionapprovedMay1,2010.PublishedJune2010.Originallyapprovedin1963.Lastpreviouseditionapprovedin2004asC518–04.DOI:10.1520/C0518-10.2Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendofthistestmethod.1Copyright.©ASTMInternational,100BarrHarbourDrive,P.O.BoxC-700WestConshohocken,Pennsylvania19428-2959,UnitedStates1.13ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.14Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoconsultandestablishappropriatesafetyandhealthpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:3C167TestMethodsforThicknessandDensityofBlanketorBattThermalInsulationsC168TerminologyRelatingtoThermalInsulationC177TestMethodforSteady-StateHeatFluxMeasure-mentsandThermalTransmissionPropertiesbyMeansoftheGuarded-Hot-PlateApparatusC236TestMethodforSteady-StateThermalPerformanceofBuildingAssembliesbyMeansofaGuardedHotBox4C687PracticeforDeterminationofThermalResistanceofLoose-FillBuildingInsulationC976TestMethodforThermalPerformanceofBuildingAssembliesbyMeansofaCalibratedHotBox4C1045PracticeforCalculatingThermalTransmissionProp-ertiesUnderStead