ASTM_D_7897_-_18.pdf

Designation:D789718Standard Practice forLaboratory Soiling and Weathering of Roofing Materials toSimulate Effects of Natural Exposure on Solar Reflectanceand Thermal Emittance1This standard is issued under the fixed designation D7897;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 Practice D7897 applies to simulation of the effects offield exposure on the solar reflectance and thermal emittance ofroof surface materials including but not limited to field-appliedcoatings,factory-applied coatings,single-ply membranes,modified bitumen products,shingles,tiles,and metal products.The solar reflectance and thermal emittance of roof surfacingmaterials can be changed by exposure to the outdoor environ-ment.These changes are caused by three factors:depositionand retention of airborne pollutants;microbiological growth;and changes in physical or chemical properties.This practiceapplies to simulation of changes in solar reflectance andthermal emittance induced by deposition and retention ofairborne pollutants and,to a limited extent,changes caused bymicrobiological growth.1.2 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.1.3 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:2C1371 Test Method for Determination of Emittance ofMaterials Near Room Temperature Using Portable Emis-sometersC1549 Test Method for Determination of Solar ReflectanceNearAmbient Temperature Using a Portable Solar Reflec-tometerE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG151 Practice for Exposing Nonmetallic Materials inAccel-erated Test Devices that Use Laboratory Light SourcesG154 Practice for Operating Fluorescent Ultraviolet(UV)Lamp Apparatus for Exposure of Nonmetallic Materials2.2 Other Standards:ANSI/CRRC S100 Standard Test Methods for DeterminingRadiative Properties of Materials33.Terminology3.1 Definitions:3.1.1 solar energythe radiant energy originating from thesun.3.1.1.1 DiscussionApproximately 99%of terrestrial solarradiation lies between the wavelengths of 0.3 and 2.5 m,withpeak radiation near 0.5 m.This spectrum includes ultraviolet,visible,and near-infrared radiation.3.1.2 solar reflectancethe fraction of incident solar fluxreflected by a surface.3.1.3 thermal emittanceefficiency with which a surfaceemits thermal radiation,measured on a scale from 0 to 1,wherea value of 1 indicates perfect emission(that is,equal to that ofa black body).3.1.4 thermal radiationthe radiant energy originatingfrom a 300 K(about 27C)black body.3.1.4.1 DiscussionApproximately 99%of thermal radia-tion lies between the wavelengths of 4 and 80 m,with peakradiation near 10 m.4.Summary of Practice4.1 This practice presents a rapid laboratory method forweathering and soiling,which simulates natural changes insolar reflectance and thermal emittance of materials in the field.1This practice is under the jurisdiction ofASTM Committee D08 on Roofing andWaterproofing and is the direct responsibility of Subcommittee D08.20 on RoofingMembrane Systems.Current edition approved March 15,2018.Published July 2018.Originallyapproved in 2015.Last previous edition approved in 2015 as D7897 15.DOI:10.1520/D7897-18.2For 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.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright 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.1 The practice describes a simulated field exposure protocol thatconsists of spraying an aqueous mixture of soot and othersoluble soiling constituents,including salts and organic matter,onto a specimen of roof surfacing material.The specimen isexposed in a weather