1、Designation:D97421Designation:139/98(2017)Standard Test Method forAcid and Base Number by Color-Indicator Titration1This standard is issued under the fixed designation D974;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of
2、last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope*1.1 This test method covers the determina
3、tion of acidic orbasic constituents(Note 1)in petroleum products2and lubri-cants soluble or nearly soluble in mixtures of toluene andisopropyl alcohol.It is applicable for the determination of acidsor bases whose dissociation constants in water are larger than109;extremely weak acids or bases whose
4、dissociationconstants are smaller than 109do not interfere.Salts react iftheir hydrolysis constants are larger than 109.NOTE1In new and used oils,the constituents considered to haveacidic characteristics include organic and inorganic acids,esters,phenoliccompounds,lactones,resins,salts of heavy meta
5、ls,and addition agentssuch as inhibitors and detergents.Similarly,constituents considered tohave basic properties include organic and inorganic bases,aminocompounds,salts of weak acids(soaps),basic salts of polyacidic bases,salts of heavy metals,and addition agents such as inhibitors anddetergents.N
6、OTE2This test method is not suitable for measuring the basicconstituents of many basic additive-type lubricating oils.Test MethodD4739 can be used for this purpose.1.2 This test method can be used to indicate relative changesthat occur in an oil during use under oxidizing conditions.Although the tit
7、ration is made under definite equilibriumconditions,the method does not measure an absolute acidic orbasic property that can be used to predict performance of an oilunder service conditions.No general relationship betweenbearing corrosion and acid or base numbers is known.NOTE3Oils,such as many cutt
8、ing oils,rustproofing oils,and similarcompounded oils,or excessively dark-colored oils,that cannot be ana-lyzed for acid number by this test method due to obscurity of thecolor-indicator end point,can be analyzed by Test Method D664.The acidnumbers obtained by this color-indicator test method need n
9、ot benumerically the same as those obtained by Test Method D664,the basenumbers obtained by this color indicator test method need not benumerically the same as those obtained by Test Method D4739,but theyare generally of the same order of magnitude.1.3 The values stated in SI units are to be regarde
10、d 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
11、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-men
12、dations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:3D117 Guide for Sampling,Test Methods,and Specificationsfor Electrical Insulating LiquidsD664 Test Method for Acid Number of Petroleum Productsby Potentiometric TitrationD
13、1193 Specification for Reagent WaterD4175 Terminology Relating to Petroleum Products,LiquidFuels,and LubricantsD4739 Test Method for Base Number Determination byPotentiometric Hydrochloric Acid Titration3.Terminology3.1 Definitions:3.1.1 acid number,nthe quantity of a specified base,expressed in mil
14、ligrams of potassium hydroxide per gram ofsample,required to titrate a sample in a specified solvent to aspecified endpoint using a specified detection system.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsi
15、bility ofSubcommittee D02.06 on Analysis of Liquid Fuels and Lubricants.In the IP,this test method is under the jurisdiction of the StandardizationCommittee.This test method was adopted as a joint ASTM-IP standard in 1965.Current edition approved July 1,2021.Published July 2021.Originally approvedin
16、 1948.Last previous edition approved in 2014 as D974 142.DOI:10.1520/D0974-21.2Statements defining this test method,its modification,and its significance whenapplied to electrical insulating oils of mineral origin will be found in Guide D117.3For 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 se
