ASTM_D_7990_-_21.pdf

Designation:D799021An American National StandardStandard Test Method forUsing Reflectance Spectra to Produce an Index ofTemperature Rise in Polymeric Siding1This standard is issued under the fixed designation D7990;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.Scope*1.1 This test method uses reflectance spectra from theultraviolet,visible,and near infrared region to produce anindex of the temperature rise of polymeric siding aboveambient temperature that occurs due to absorption of the sunsenergy.1.2 The test method determines the intensity factor of asample color.The intensity factor is a function of the samplesreflectance spectra and the energy output of the heat lamp usedin the test method Test Method D4803.1.3 Appendix X1 provides a method for using the intensityfactor to determine the maximum temperature rise of a sampleunder severe solar exposure.1.3.1 A correlation between intensity factor and heatbuildup(temperature rise)as predicted by Test Method D4803exists.1.3.2 The heat buildup(temperature rise)for a polymericbuilding product specimen is determined from its reflectancespectra and the correlations regression equation.1.4 UnitsThe values stated in SI units are to be regardedas standard.No other units of measurement are included in thisstandard.1.5 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:D2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesD4803 Test Method for Predicting Heat Buildup in PVCBuilding ProductsE903 Test Method for Solar Absorptance,Reflectance,andTransmittance of Materials Using Integrating SpheresE1331 Test Method for Reflectance Factor and Color bySpectrophotometry Using Hemispherical Geometry3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 fractionalabsorptanceoneminusFractionalReflectance,1 R.3.1.2 fractional reflectancethe percentage of energy re-flected by a sample at a given wavelength,divided by 100.3.1.3 intensity factoran indicator of a specimens heatbuildup based on its reflectance spectrum and the energy outputof the IR lamp used in Test Method D4803.3.1.3.1 DiscussionThe intensity factor is a summationproduct of the heat lamps relative intensity and the specimensfractional absorptance at 20 nm intervals between 200 and2,500 nm.3.1.4 heat buildupthe temperature rise above that ofambient air due to the amount of energy absorbed from the sunby a specimen.3.1.5 relative intensity(of heat lamp)the lamps spectraloutput across the range of 200 nm to 2500 nm,normalized toa value of 100 at the lamps maximum output.4.Summary of Test Method4.1 The specimens size must cover the spectrophotometersmeasurement port,typically 25.4 mm in diameter.Typicalsample dimensions are 102 by 102 by 1.3 mm.4.2 Ablack backer card or plaque is used directly behind thespecimen to absorb any radiant energy transmitted through thespecimen.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.24 on Plastic BuildingProducts.Current edition approved April 1,2021.Published April 2021.Originallyapproved in 2015.Last previous edition approved in 2015 as D7990 15.DOI:10.1520/D799021.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.14.3 The spectral reflectance curve of the test specimen ismeasured to determine the amount of energy the specimenabsorbs at each wavelength.4.4 The intensity factor of the test specimen is the result ofa series summation for the specimens spectral absorptance andthe relative intensity of the IR lamp used in Test MethodD4803.The product of the specimens spectral absorptance andrelative intensity is determined for the spectral region of 200 2,500 nm at