Designation:D4230−02(Reapproved2012)StandardTestMethodofMeasuringHumiditywithCooled-SurfaceCondensation(Dew-Point)Hygrometer1ThisstandardisissuedunderthefixeddesignationD4230;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversthedeterminationofthether-modynamicdew-orfrost-pointtemperatureofambientairbythecondensationofwatervaporonacooledsurface.Forbrevitythisisreferredtointhismethodasthecondensationtemperature.1.2Thistestmethodisapplicablefortherangeofconden-sationtemperaturesfrom60°Cto−70°C.1.3Thistestmethodincludesageneraldescriptionoftheinstrumentationandoperationalprocedures,includingsiteselection,tobeusedforobtainingthemeasurementsandadescriptionoftheprocedurestobeusedforcalculatingtheresults.1.4Thistestmethodisapplicableforthecontinuousmea-surementofambienthumidityinthenaturalatmosphereonastationaryplatform.1.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.Forspecificprecautionarystatements,seeSection8.2.ReferencedDocuments2.1ASTMStandards:2D1356TerminologyRelatingtoSamplingandAnalysisofAtmospheresD3631TestMethodsforMeasuringSurfaceAtmosphericPressure3.Terminology3.1Definitions:3.1.1Fordefinitionsofothertermsinthismethod,refertoTerminologyD1356.3.2DefinitionsofTermsSpecifictoThisStandard:3.2.1nonhygroscopicmaterial—materialthatneitherab-sorbsnorretainswatervapor.3.2.2mirror(frontsurface)—apolishedsurface,usuallyametallicsurface,onwhichcondensatesaredeposited.3.3Symbols:e=vaporpressureofwatervaporinmoistair.ei=saturationpressureofwatervaporinequilibriumwiththeplanesurfaceofice.ew=saturationpressureofwatervaporinequilibriumwiththepla...
