ASTM_D_4425_-_19.pdf

Designation:D442519Standard Test Method forOil Separation from Lubricating Grease by Centrifuging(Koppers Method)1This standard is issued under the fixed designation D4425;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 covers a procedure for determining thetendency of lubricating grease to separate oil when subjected tohigh centrifugal forces.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 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.1.4 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.2.Referenced Documents2.1 ASTM Standards:2D217 Test Methods for Cone Penetration of LubricatingGrease3.Terminology3.1 Definitions:3.1.1 lubricating grease,na semi-fluid to solid product ofa dispersion of a thickener in a liquid lubricant.3.1.1.1 DiscussionThe dispersion of the thickener forms atwo-phase system and immobilizes the liquid lubricant bysurface tension and other physical forces.Other ingredients arecommonly included to impart special properties.D2173.1.2 thickener,nin lubricating grease,a substance com-posed of finely-divided particles dispersed in a liquid to formthe productss structure.3.1.2.1 DiscussionThickeners can be fibers(such as vari-ous metallic soaps)or plates or spheres(such as certainnon-soap thickeners),which are insoluble or,at most,only veryslightly soluble in the liquid lubricant.The general require-ments are that the solid particles be extremely small,uniformlydispersed,and capable of forming a relatively stable,gel-likestructure with the liquid lubricant.3.2 Symbols:a=distance from top of grease surface to tube mouth(mm).b=height of liquid column in an inverted test tube(mm).d=test tube inside diameter(mm).H=accumulated test time at a given reading(h).K36=resistance to centrifugal separation(V/H).r=measured at the maximum radius of rotation(mm).rpm=rotational speed(r/min).V=volume of separated oil,as a percentage of theoriginal grease volume(%).Vg=grease volume in a test tube(cm3).Vo=volume of separated oil(cm3).Vt=test tube total volume(cm3).A=angle of rotor,between the test tube axis and axis ofrotation(degrees).=rotational speed(rad/s).G=relative centrifugal acceleration.3.3 The relative effect of centrifugal forces,when related tothe gravitational standard acceleration(9.81 m s2),is notedwith the symbol G.It can be calculated as follows:G 5 1.02310243r 32(1)orG 5 1.12310263r 3rpm2(2)4.Summary of Test Method4.1 Pairs of centrifuge tubes are charged with greasesamples and are placed in the centrifuge.The grease samplesare subjected to a centrifugal force equivalent to a G value of36 000,at 50 C 6 1 C,for specific periods of time.The1This test method is under the jurisdiction of Committee D02 on PetroleumProducts,Liquid Fuels,and Lubricants and is the direct responsibility of Subcom-mittee D02.G0.03 on Physical Tests.Current edition approved June 1,2019.Published July 2019.Originally approvedin 1984.Last previous edition approved in 2014 as D4425 09(2014).DOI:10.1520/D4425-19.2For 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 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 Barriers to Trade(TBT)Committee.1 resistance of the grease to separate the oil is then defined as aratio of the percent of oil separated to the total number of hoursof testing.5.Significance and Use5.1 This test method is useful in evaluating the degree towhich a grease would separate into fluid and solid componentswhen subjected to high centrifugal forces.Flexible shaftcouplings,universal joints,and rolling element thrust bearingsare examples of machinery which subject lubricating greases tolarg