1、Designation:D66411aBritish Standard 4457Designation 177/96Standard Test Method forAcid Number of Petroleum Products by PotentiometricTitration1This standard is issued under the fixed designation D664;the number immediately following the designation indicates the year oforiginal adoption or,in the ca
2、se 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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope*1.1 This test
3、method covers procedures for the determina-tion of acidic constituents in petroleum products,lubricants,biodiesel and blends of biodiesel.1.1.1 Test Method AFor petroleum products and lubricantssoluble or nearly soluble in mixtures of toluene and propan-2-ol.It is applicable for the determination of
4、 acids whosedissociation constants in water are larger than 10-9;extremelyweak acids whose dissociation constants are smaller than 10-9do not interfere.Salts react if their hydrolysis constants arelarger than 10-9.The range of acid numbers included in theprecision statement is 0.1 mg/g KOH to 150 mg
5、/g KOH.1.1.2 Test Method BDeveloped specifically for biodieseland biodiesel blends with low acidity and slightly differentsolubility.This test method requires the use of an automatictitrator with automatic endpoint seeking capability.NOTE1In new and used oils,the constituents that may be consideredt
6、o have acidic characteristics include organic and inorganic acids,esters,phenolic compounds,lactones,resins,salts of heavy metals,salts ofammonia and other weak bases,acid salts of polybasic acids,and additionagents such as inhibitors and detergents.1.2 The test method may be used to indicate relati
7、vechanges that occur in oil during use under oxidizing conditionsregardless of the color or other properties of the resulting oil.Although the titration is made under definite equilibriumconditions,the test method is not intended to measure anabsolute acidic property that can be used to predict perf
8、or-mance of oil under service conditions.No general relationshipbetween bearing corrosion and acid number is known.NOTE2The acid number obtained by this standard may or may not benumerically the same as that obtained in accordance with Test MethodsD974 and D3339.There has not been any attempt to cor
9、relate this methodwith other non-titration methods.NOTE3A few laboratories have made the observation that there is adifference in Test Method D664 results when aqueous versus nonaqueousbuffers are used.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are
10、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
11、to use.2.Referenced Documents2.1 ASTM Standards:2D974 Test Method for Acid and Base Number by Color-Indicator TitrationD1193 Specification for Reagent WaterD3339 Test Method forAcid Number of Petroleum Productsby Semi-Micro Color Indicator TitrationD4057 Practice for Manual Sampling of Petroleum and
12、Petroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsE177 Practice for Use of the Terms Precision and Bias inASTM Test Methods3.Terminology3.1 Definitions:3.1.1 acid number,nthe quantity of a specified base,expressed in milligrams of potassium hydroxide per gram
13、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 responsibility ofSubcommittee D02.06 on Analysis
14、 of Lubricants.Current edition approved July 15,2011.Published August 2011.Originallyapproved in 1942.Last previous edition approved in 2011 as D66411.DOI:10.1520/D0664-11A.This test method was adopted as a joint ASTM-IP standard in 1964.ASTM TestMethod D4739 has been developed as an alternative to
15、the base number portion ofD664.2For 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.*A Summary of Changes section appea
16、rs at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.1.1 DiscussionThis test method expresses the quantityof base as milligrams of potassium hydroxide per gram ofsample,that is required to titrate a sample in a mixture oftoluene and propan-2-ol to which a small amount of water hasbeen added from its initial meter reading in millivolts to ameter reading in millivolts corresponding to an aqueous basicbuffer
