ASTM_D_5770_-_11.pdf

Designation:D577011Standard Test Method forSemiquantitative Micro Determination of Acid Number ofLubricating Oils During Oxidation Testing1This standard is issued under the fixed designation D5770;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.Scope*1.1 This test method is a semiquantitative micro methodintended for monitoring the changes in acidic constituentsoccurring in lubricating oils during oxidation testing,when theacid number of such oils falls within the range from 0.02 to 1.0mg of potassium hydroxide per gram of sample.It is applicableto such oils as turbine oils,hydraulic oils,and other circulatingoils.NOTE1This test method is a micro version of Test Method D974 andit produces results similar to that method.1.2 This test method is designed for use where sample sizeis limited.It shall not be used as a replacement for higherprecision methods such as Test Methods D974 or D664.It shallnot be used to monitor oils in-service.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.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:2D664 Test Method for Acid Number of Petroleum Productsby Potentiometric TitrationD943 Test Method for Oxidation Characteristics of InhibitedMineral OilsD974 Test Method for Acid and Base Number by Color-Indicator TitrationD3339 Test Method forAcid Number of Petroleum Productsby Semi-Micro Color Indicator TitrationD4871 Guide for Universal Oxidation/Thermal StabilityTest Apparatus3.Terminology3.1 Definitions:3.1.1 acid number,nthe quantity of a specified base,expressed in milligrams of potassium hydroxide per gram ofsample,required to titrate a sample in a specified solvent to aspecified endpoint using a specified detection system.3.1.1.1 DiscussionIn this test method,the acid number iscalculated from the number of drops required to produce achange in solution color from blue-green to orange,comparedto the number of drops required to produce an identical colorchange using a reference standard.Because this is a directcomparison method,the acid number value can be reported inmilligrams of potassium hydroxide per gram of sample.4.Summary of Test Method4.1 A2.0-mL portion of the titration solution is titrated witha sample using a dropping pipet.The number of drops ofsample required to turn the blue-green titration solution to apersistent orange color is noted.4.2 A second 2.0-mL portion of the titration solution istitrated with an acid number reference solution of known acidnumber.The number of drops of the reference solutionrequired to turn the blue-green titration solution to a persistentorange color is noted.4.3 The estimated acid number of the sample is calculatedusing the acid number of the reference solution and the ratio ofthe number of drops of the reference solution required to effectthe color change to the number of drops of the sample requiredfor the same change.5.Significance and Use5.1 This test method provides a semiquantitative estimate ofthe acid number of lubricating oils obtained from laboratoryoxidation tests using smaller amounts of sample than TestMethods D974,D664,or D3339.It has specific application inTest Method D943 and in Test Method D4871.This testmethod,therefore,provides a means of monitoring the relative1This 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 1995.Last previous edition approved in 2007 as D577002(2007).DOI:10.1520/D5770-11.2For 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 oxidation of lubricating oils by measuring changes in acidnumber,at different time intervals and under various oxidizingtest conditions.5.2 Since this test method is semiquantitative,each labora-tory shall develop its own criteria for each oxidation testmethod for determining when to switch from this semiquanti-tative test method to a more precise test method for acidnumber.6.Apparatus6.1 Glass Beakers,10-mL capacity,or glass vials,4 or