1、Designation:D442509(Reapproved 2014)Standard 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 revis
2、ion,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.Scope1.1 This test method covers a procedure for determining thetendency of lubricating grease to separate oil when
3、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
4、 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:2D217 Test Methods for Cone Penetration of LubricatingGrease3.Terminology3.1 Definitions:3.1.1 lubricating grease,na s
5、emi-fluid to solid product ofa 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 thic
6、kener,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
7、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=heigh
8、t 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 theori
9、ginal 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 forc
10、es,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 3rpmacb2(2)4.Summary of Test Method4.1 Pairs of centrifuge tubes are charged with greasesamples and are placed in the centrifuge.The g
11、rease samplesare subjected to a centrifugal force equivalent to a G value of36 000,at 50C 6 1C,for specific periods of time.Theresistance 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
12、test method is useful in evaluating the degree towhich a grease would separate into fluid and solid componentswhen subjected to high centrifugal forces.Flexible shaft1This test method is under the jurisdiction of Committee D02 on PetroleumProducts,Liquid Fuels,and Lubricants and is the direct respon
13、sibility of Subcom-mittee D02.G0.03 on Physical Tests.Current edition approved Oct.1,2014.Published November 2014.Originallyapproved in 1984.Last previous edition approved in 2009 as D4425 09.DOI:10.1520/D4425-09R14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Cu
14、stomer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 couplings,universal joints,and rolling e
15、lement thrust bearingsare examples of machinery which subject lubricating greases tolarge and prolonged centrifugal forces.This test method hasbeen found to give results that correlate well with results fromactual service.The test method may be run at other conditionswith agreement between parties b
16、ut the precision noted in thistest method will no longer apply.36.Apparatus6.1 High-Speed Centrifuge,capable of developing a G valueof 36 000.Mount the unit on a flat level surface to allowunrestricted air flow to the motor.This is essential for longmotor life.The centrifuge should be equipped with:6.1.1 Fixed Angle Rotor,multiple place,which can sustain aG value of 36 000.6.1.2 Thermometer,preferably of a dial type,installed sothat the temperature in the vicinity(5 to 15 mm)of the rotorcan be m