ASTM_D_7238_-_06_2012.pdf

Designation:D723806(Reapproved 2012)Standard Test Method forEffect of Exposure of Unreinforced PolyolefinGeomembrane Using Fluorescent UV CondensationApparatus1This standard is issued under the fixed designation D7238;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 standard covers the specific procedures and testconditions that are applicable for exposure of unreinforcedpolyolefin geomembranes to fluorescent UV radiation andcondensation.NOTE1Polyolefin geomembranes include high density polyethylene(HDPE),linear low density polyethylene(LLDPE),flexible polyproply-ene(fPP),etc.1.2 Test specimens are exposed to fluorescent UVA 340lamps under controlled environmental conditions.UVA 340lamps are standard for this method.NOTE2Other types of fluorescent UV lamps,such as UVB-313,canalso be used based upon discussion between involved parties.However,ifthe test is ran with another type of fluorescent UV lamps,such asUVB-313,this should be considered as a deviation from the standard andclearly stated in the test report.UVB-313 and UVA-340 fluorescent lampsgenerate different amount of radiant power in different wavelength ranges;thus,the photochemical effects caused by these different lamps may vary.1.3 This method covers the conditions under which theexposure is to be performed and the test methods for evaluatingthe effects of fluorescent UV,heat and moisture in the form ofcondensation on geomembranes.General guidance is given inPractices G151 and G154.1.4 The values listed in SI units are to be regarded as thestandard.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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1238 Test Method for Melt Flow Rates of Thermoplasticsby Extrusion PlastometerD5885 Test Method for Oxidative Induction Time of Poly-olefin Geosynthetics by High-Pressure Differential Scan-ning CalorimetryD6693 Test Method for Determining Tensile Properties ofNonreinforced Polyethylene and Nonreinforced FlexiblePolypropylene GeomembranesG113 Terminology Relating to Natural and Artificial Weath-ering Tests of Nonmetallic MaterialsG151 Practice for Exposing Nonmetallic Materials inAccel-erated Test Devices that Use Laboratory Light SourcesG154 Practice for Operating Fluorescent LightApparatus forUV Exposure of Nonmetallic MaterialsG156 Practice for Selecting and Characterizing WeatheringReference Materials3.Terminology3.1 Definitions:(According to Terminology G113).3.1.1 control,nAmaterial which is of similar compositionand construction to the test material used for comparison,exposed at the same time.3.1.2 irradiance,nthe radiant power per unit area incidenton a receiver,typically reported in units of W/(m2.nm)atspecified wavelength of measurement or in W/m2in a specifiedspectral range.3.1.3 reference material,nA material with known perfor-mance.3.1.4 ultraviolet regions,nThe UV region of the spectrumis divided into three regions:UVA,radiation in wavelengths1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.02 on Endur-ance Properties.Current edition approved July 1,2012.Published July 2012.DOI:10.1520/D7238-06R20122For 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 between 315 nm and 400 nm;UVB,radiation in wavelengthsbetween 280 nm and 315 nm;and UVC,radiation in wave-lengths shorter than 280 nm(Ref.CIE Publication No.20(1972).4.Summary of Test Method4.1 Geomembrane coupons are exposed to repetitive cyclesconsisting of ultraviolet radiation at a specified temperaturefollowed by moisture in the form of condensation at a specifiedtemperature in the absence of ultraviolet radiation.4.2 The UV source is provided by fluorescent UVA-340lamps,with lamp emissions peaking at 343 nm.4.3 Water vapor shall be generated by heating water andfilling the chamber with hot vapor,which then is made tocondense on the front of the test coupons.The reverse side ofthe coupons is exposed to the cooling influence of ambientroom air.4.4 While this standard prescribes a particular set of expo-sure conditions,such conditions may be varied by agreementbetween the parties involved in the agreement or contract.Suchvariation may include the irradiance,the selection of thefluorescent UV lamp