ASTM_C_1371_-_15.pdf

Designation:C137115Standard Test Method forDetermination of Emittance of Materials Near RoomTemperature Using Portable Emissometers1This standard is issued under the fixed designation C1371;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers a technique for determination ofthe emittance of opaque and highly thermally conductivematerials using a portable differential thermopile emissometer.The purpose of the test method is to provide a comparativemeans of quantifying the emittance of materials near roomtemperature.1.2 This test method does not supplant Test Method C835,which is an absolute method for determination of total hemi-spherical emittance,or Test Method E408,which includes twocomparative methods for determination of total normal emit-tance.Because of the unique construction of the portableemissometer,it can be calibrated to measure the total hemi-spherical emittance.This is supported by comparison ofemissometer measurements with those of Test Method C835(1).21.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:3C168 Terminology Relating to Thermal InsulationC680 Practice for Estimate of the Heat Gain or Loss and theSurface Temperatures of Insulated Flat,Cylindrical,andSpherical Systems by Use of Computer ProgramsC835 Test Method for Total Hemispherical Emittance ofSurfaces up to 1400CE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE408 Test Methods for Total Normal Emittance of SurfacesUsing Inspection-Meter TechniquesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 DefinitionsFor definitions of some terms used in thistest method,refer to Terminology C168.3.2 Definitions of Terms Specific to This Standard:3.2.1 diffuse surfacea surface that emits or reflects equalradiation intensity,or both,in all directions(2).3.2.2 emissive powerthe rate of radiative energy emissionper unit area from a surface(2).3.2.3 emissometeran instrument used for measurement ofemittance.3.2.4 Lamberts cosine lawthe mathematical relation de-scribing the variation of emissive power from a diffuse surfaceas varying with the cosine of the angle measured away from thenormal of the surface(2).3.2.5 normal emittancethe directional emittance perpen-dicular to the surface.3.2.6 radiative intensityradiative energy passing throughan area per unit solid angle,per unit of the area projectednormal to the direction of passage,and per unit time(2).3.2.7 spectralhaving a dependence on wavelength;radia-tion within a narrow region of wavelength(2).3.2.8 specular surfacemirrorlike in reflection behavior(2).3.3 Symbols:3.3.1 For standard symbols used in this test method,seeTerminology C168.Additional symbols are listed here:=total absorptance,dimensionless=spectral absorptance,dimensionlesshi=total emittance of the high-emittance calibrationstandard,dimensionless1This test method is under the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved March 1,2015.Published June 2015.Originallyapproved in 1997.Last previous edition approved in 2010 as C1371-04a(2010)1.DOI:10.1520/C1371-15.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 low=total emittance of the low-emittance calibrationstandard,dimensionlessspec=apparent total emittance of the test specimen,dimen-sionless=apparent total emittance of the surface,dimensionless1=apparent total emittance of the surface 1,dimensionless2=apparent total emittance of the surface 2,dimensionlessd=apparent total emittance of the surface of detector,dimensionlesss=apparent total emittance of the surface of specimen,dimensionless=spectral emittance,dimensionless=wavelength,m=total reflectance,dimensionless=Stefan-Boltzmann constant,5.6696 108W/m2 K4=total transmittance,dimensionlessA=area of surface,m2k=proportionality constant,Vm2/WQrad=radiation heat transfer,Wqrad=radiative heat