ASTM_D_2896_-_11.pdf

Designation:D289611Standard Test Method forBase Number of Petroleum Products by PotentiometricPerchloric Acid Titration1This standard is issued under the fixed designation D2896;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.This standard has been approved for use by agencies of the Department of Defense.1.Scope*1.1 This test method covers the determination of basicconstituents in petroleum products by titration with perchloricacid in glacial acetic acid.1.2 Procedures A and B use different titration solventvolumes and sample weights.NOTE1A round robin on a series of new and used oils and additiveconcentrates has shown that the two procedures give statistically equiva-lent results.1.3 Appendix X2 provides the use of an alternative solventsystem which eliminates the use of chlorobenzene in this testmethod.The use of the alternative solvent gives statisticallyequivalent results;however,the precision is worse.ParagraphX2.5.5 provides guidance when comparing results using thetwo different solvents.1.4 The constituents that may be considered to have basiccharacteristics include organic and inorganic bases,aminocompounds,salts of weak acids(soaps),basic salts of poly-acidic bases,and salts of heavy metals.NOTE2This test method is applicable to both fresh oils and used oilsas described in Sections 16,17,and 19 and Appendix X1.1.5 This test method can be used to determine base number300 mg KOH/g.However,the precision statement in Section19 has been obtained only on base number 300 mg KOH/g.1.6 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.7 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.For specificwarning statements,see Section 7,Section 10,and X2.2.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent Water3.Terminology3.1 Definitions:3.1.1 base numberthe quantity of a specified acid,ex-pressed in terms of the equivalent number of milligrams ofpotassium hydroxide per gram of sample,required to titrate asample in a specified solvent to a specified endpoint using aspecified detection system.4.Summary of Test Method4.1 The sample is dissolved in an essentially anhydrousmixture of chlorobenzene and glacial acetic acid and titratedwith a solution of perchloric acid in glacial acetic acid usingpotentiometric titrimeter.A glass indicating electrode and areference electrode are used,the latter being connected withthe sample solution by means of a salt bridge.The meterreadings are plotted against the respective volumes of titratingsolution,and the end point is taken at the inflection in theresulting curve.4.2 Procedure A uses 120 mL of titration solvent.ProcedureB uses 60 mL of titration solvent.In addition,the twoprocedures use different equations for the calculation of appro-priate sample weights.Since many portions of the test methodare identical for Procedures A and B,only the unique sectionswill be described separately for the two versions of the testmethod.4.3 Occasionally certain used oils give no inflection in theforward titration mode,in which case a back titration modifi-cation with sodium acetate titrant is employed.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.06 on Analysis of Lubricants.Current edition approved May 15,2011.Published July 2011.Originallyapproved in 1970.Last previous edition approved in 2007 as D289607a.DOI:10.1520/D2896-11.This test method has been approved by the sponsoring committees and acceptedby the cooperating societies in accordance with established procedures.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 appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Significance and Use5.1 New and used petroleum products can contain basicconstituents that are present as additives.The relative amountsof these materials can be determined by titration with acids.The base number is a measure of the amount of basic substancein the oil,always under the conditions of the test.It issometimes used as a measure of lubricant degradation inservice;however,any condemning limits must be empiricallyestablished.6.Apparatus6.1 Potentiome