ASTM_D_7736_-_12.pdf

Designation:D773612Standard Test Method forDetermination of Acids and Glycol Esters in EthyleneGlycol1This 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.Scope1.1 This test method covers the determination of free acidsand glycol esters in ethylene glycol by titration.1.2 This test method is for used on ethylene glycol used forthe manufacture of engine coolant.It can not be used onformulated engine coolant.The inhibitors will interfere withthe determination.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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1176 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 FluidsE177 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 ethylene glycol by titration.The sample is titrated tothe phenolphthalein end point with 0.02 N NaOH to determinethe acidity.Then a known amount of base is added and thesample is heated at 100C to hydrolyze the esters.It is thenback-titrated with 0.02 N sulfuric acid to determine the estercontent.5.Significance and Use5.1 The presence of acids or glycol esters in the ethyleneglycol used to produce engine coolant is undesirable.Underconditions in an engine cooling system,the esters can hydro-lyze to form glycol and an acid.The acid will react with thecorrosion inhibitors,thereby reducing the useful life of thecoolant.This method can determine the amount of acid andglycol ester present in the ethylene 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.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 Analytical Reagents of the American Chemical Society,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 April 1,2012.Published June 2012.Originallyapproved in 2011.Last previous edition approved in 2011 as D7736-11.DOI:10.1520/D773612.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 where such specifications are available.3Other grades may beused,provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.9.Sampling9.1 Sample the material in accordance with Practice D1176.10.Procedure10.1 Acid Content:10.1.1 Adjustment of pHPipet 25.00 mL of deionizedwater into each of three 250 mL bottles.Add 3 drops ofphenolphthalein solution to each.Titrate with 0.02 N sodiumhydroxide to the first pink end point permanent for at least 15seconds.Do not record this volume of titrant.Repeat for eachbottle.10.1.2 Determination of Sample Acidity:10.1.2.1 Add an amount of sample as indicated in Table 1 tothe nearest 0.1 g into the bottle of deionized water prepared in10.1.1.10.1.2.2 Titrate each sample with 0.02 N sodium hydroxideto the first pink end point permanent for at least 15 s.Thisvolume of titrant