ASTM_D_6971_-_22.pdf

Designation:D697122Standard Test Method forMeasurement of Hindered Phenolic and Aromatic AmineAntioxidant Content in Non-zinc Turbine Oils by LinearSweep Voltammetry1This standard is issued under the fixed designation D6971;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 covers the voltammetric determinationof hindered phenol and aromatic amine antioxidants in new orin-service type non-zinc turbine oils in concentrations from0.0075%by mass up to concentrations found in new oils bymeasuring the amount of current flow at a specified voltage inthe produced voltammogram.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:2D1193 Specification for Reagent WaterD2272 Test Method for Oxidation Stability of Steam Tur-bine Oils by Rotating Pressure VesselD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4175 Terminology Relating to Petroleum Products,LiquidFuels,and LubricantsD4378 Practice for In-Service Monitoring of Mineral Tur-bine Oils for Steam,Gas,and Combined Cycle TurbinesD6224 Practice for In-Service Monitoring of Lubricating Oilfor Auxiliary Power Plant EquipmentD6810 Test Method for Measurement of Hindered PhenolicAntioxidant Content in Non-Zinc Turbine Oils by LinearSweep Voltammetry2.2 ISO Standards:3ISO 6743 Part 4,Lubricants,Industrial Oils,and RelatedProducts3.Terminology3.1 Definitions:3.1.1 See Terminology D4175 for a more extensive list ofterms used in this test method.3.1.2 electrolytic cell,nan electrochemical cell in whichchemical reactions are caused by applying an external potentialdifference greater than,and opposite to,the galvanic electro-motive force of the cell.IUPAC43.1.3 linear sweep voltammetry,na technique applied tothe monitoring of antioxidant additive content in lubricants,where the current is detected as an applied potential isincreased linearly over a period of time.3.1.4 voltammogram,nthe plot of current versus voltage.4.Summary of Test Method4.1 A measured quantity of sample is dispensed into a vialcontaining a measured quantity of acetone based electrolytetest solution and a layer of sand.When the vial is shaken,thehindered phenol and aromatic amine antioxidants and other testsolution soluble oil components present in the sample areextracted into the test solution and the remaining dropletssuspended in the test solution are agglomerated by the sand.The sand/droplet suspension is allowed to settle out and thehindered phenol and aromatic amine antioxidants dissolved inthe test solution are quantified by voltammetric analysis.Theresults are calculated and reported as mass%of antioxidant or1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.09.0C on Oxidation of Turbine Oils.Current edition approved Nov.1,2022.Published November 2022.Originallyapproved in 2004.Last previous edition approved in 2014 as D6971 09(2014).DOI:10.1520/D6971-22.2For 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.4Inczedy,J.,Lengyel,T.,and Ure,A.M.,Orange Book:IUPAC Compendium onAnalytical Nomenclature,Definitive Rules 1997,3rd Edition,Blackwell Science,1998.*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.1as millimoles(mmol)of antioxidant per litre of sample forprepared and fresh oils and as a percent remaining antioxidantfor in-service oils.4.2 Voltammetric analysis is a technique