ASTM_D_4739_-_17.pdf

Designation:D473917Standard Test Method forBase Number Determination by Potentiometric HydrochloricAcid Titration1This standard is issued under the fixed designation D4739;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.INTRODUCTIONCurrently,there are two ASTM test methods under the jurisdiction of Committee D02 used fordetermining base number by potentiometric titration:Test Method D2896 and Test Method D4739.They are both used throughout the petroleum industry.Test Method D2896 is for new oils and is usedin setting specifications since it is more accurate than Test Method D4739.Test Method D4739 shallbe used exclusively for the purpose of tracking base number loss as an oil proceeds in service.In manycases,the test methods will provide different results.Some comparisons are given in the Scope andthe Significance and Use sections of this test method to distinguish between the two standards and toprovide guidance to users.1.Scope*1.1 This test method covers a procedure for the determina-tion of basic constituents in petroleum products and new andused lubricants.This test method resolves these constituentsinto groups having weak-base and strong-base ionizationproperties,provided the dissociation constants of the morestrongly basic compounds are at least 1000 times than that ofthe next weaker groups.This test method covers base numbersup to 250.1.2 In new and used lubricants,the constituents that can beconsidered to have basic properties are primarily organic andinorganic bases,including amino compounds.This test methoduses hydrochloric acid as the titrant,whereas Test MethodD2896 uses perchloric acid as the titrant.This test method mayor may not titrate these weak bases and,if so,it will titratethem to a lesser degree of completion;some additives such asinhibitors or detergents may show basic characteristics.1.3 When testing used engine lubricants,it should berecognized that certain weak bases are the result of the servicerather than having been built into the oil.This test method canbe used to indicate relative changes that occur in oil during useunder oxidizing or other service conditions regardless of thecolor or other properties of the resulting oil.The valuesobtained,however,are intended to be compared with the othervalues obtained by this test method only;base numbersobtained by this test method are not intended to be equal tovalues by other test methods.Although the analysis is madeunder closely specified conditions,this test method is notintended to,and does not,result in reported basic propertiesthat can be used under all service conditions to predictperformance of an oil;for example,no overall relationship isknown between bearing corrosion or the control of corrosivewear in the engine and base number.1.4 This test method was developed as an alternative for theformer base number portion of Test Method D664(lastpublished in Test Method D664 81).1.4.1 Colorimetric test methods for base number are TestMethod D974,IP 139,and 5102.1 on acid and base number byextraction(color-indicator titration)of Federal Test MethodStandard No.791b.Test results by these methods may or maynot be numerically equivalent to this test method.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6 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.1.7 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.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.06 on Analysis of Liquid Fuels and Lubricants.Current edition approved Dec.1,2017.Published February 2018.Originallyapproved in 1987.Last previous edition approved in 2017 as D4739 11(2017).DOI:10.1520/D4739-17.*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 B