ASTM_D_7736_-_19a.pdf

Designation:D773619aStandard Test Method forDetermination of Acids and Glycol Esters in Glycols1,2This standard is issued under the fixed designation D7736;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 determination of free acidsand glycol esters in glycols by titration.1.2 This test method is typically used on glycols used for themanufacture of engine coolant.It cannot be used on formulatedengine coolant.The inhibitors will interfere with the determi-nation.1.3 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 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:3D1176 Practice for Sampling and Preparing Aqueous Solu-tions of Engine Coolants orAntirusts for Testing PurposesD1193 Specification for Reagent WaterD4725 Terminology for Engine Coolants and Related FluidsD7638 Test Method for Determination of Fatty Acids andEsters in GlycerinE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method,referto Terminology D4725.4.Summary of Test Method4.1 This test method is used to determine the acid and estercontent of glycols by titration.The sample is titrated to thephenolphthalein end point with 0.02 N NaOH to determine theacidity.Then a known amount of base is added and the sampleis heated at 100 C to hydrolyze the esters.It is then back-titrated with 0.02 N sulfuric acid to determine the ester content.5.Significance and Use5.1 The presence of acids or glycol esters in the glycol usedto produce engine coolant is undesirable.Under conditions inan engine cooling system,the esters can hydrolyze to formglycol and an acid.The acid will react with the corrosioninhibitors,thereby reducing the useful life of the coolant.Thismethod can determine the amount of acid and glycol esterpresent in the glycol.6.Interferences6.1 This test method is based on a color change titration.Glycol with a strong color could interfere with the results ofthis method.6.2 High pH recycled glycols streams will affect the resultsof this test method.7.Apparatus7.1 250 mL Borosilicate Glass Bottles,with screw caps.8.Reagents and Materials8.1 Phenolphthalein SolutionDissolve 0.5 g of phenol-phthalein in methanol or ethanol and dilute to 100 mL.8.2 Sodium Hydroxide(NaOH),0.02 N in water.8.3 Sulfuric Acid(H2SO4),0.02 N in water.1This test method is under the jurisdiction of ASTM Committee D15 on EngineCoolants and Related Fluids and is the direct responsibility of SubcommitteeD15.04 on Chemical Properties.Current edition approved Nov.1,2019.Published November 2019.Originallyapproved in 2011.Last previous edition approved in 2019 as D773619.DOI:10.1520/D773619A.2This method has been qualified for use with 1,2 Ethane diol(EG),1,2 Propanediol(PG),and 1,3 Propane diol(PDO).ASTM Test Method D7638 has beenapproved for use with 1,2,3 Propane triol(glycerin,glycerol).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.*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.1 8.4 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water as definedby Type II or III of Specification D1193.8.5 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytic