1、Designation: D 4425 09An American National StandardStandard Test Method forOil Separation from Lubricating Grease by Centrifuging(Koppers Method)1This standard is issued under the fixed designation D 4425; the number immediately following the designation indicates the year oforiginal adoption or, in
2、 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 gre
3、ase 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 the
4、responsibility 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:2D 217 Test Methods for Cone Penetration of LubricatingGrease3. Terminology3.1 Definitio
5、ns:3.1.1 lubricating grease, na semi-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
6、 special properties. D 2173.1.2 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 thicken
7、ers), 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 fr
8、om 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 = rotationa
9、l 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).v = rotational speed (r
10、ad/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 1.02 3 10243 r 3v2(1)orG 5 1.12 3 10263 r 3 rpm2(2)4. Summary of Test Method4.
11、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 50C 6 1C, for specific periods of time. Theresistance of the grease to separate the oil is then defined as aratio o
12、f the percent of oil separated to the total number of hoursof testing.1This test method is under the jurisdiction of Committee D02 on PetroleumProducts and Lubricants and is the direct responsibility of Subcommittee D02.G0.03on Physical Tests.Current edition approved April 15, 2009. Published May 20
13、09. Originallyapproved in 1984. Last previous edition approved in 2002 as D 442597(2002).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 Summ
14、ary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Significance and Use5.1 This test method is useful in evaluating the degree towhich a gr
15、ease 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 tolarge and prolonged centrifugal forces. This test method hasbeen f
16、ound to give results that correlate well with results fromactual service. The test method may be run at other conditionswith agreement between parties but the precision noted in thistest method will no longer apply.36. Apparatus6.1 High-Speed Centrifuge, capable of developing a G valueof 36 000. Mou
17、nt 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 sustaina G value of 36 000.6.1.2 Thermometer, preferably of a dial type, installed sothat th
18、e temperature in the vicinity (5 to 15 mm) of the rotorcan be measured.6.1.3 Air Choke, installed at the air inlet of the centrifugechamber, and used to control the temperature if the unit lacksan automatic temperature control. Some designs require outletchoking as well.6.1.4 Centrifuge Tubes, made
19、of transparent material, ca-pable of withstanding a G value of 36 000 for 100 h minimum(Note 1).NOTE 1Polypropylene tubes were found to be the most durable.6.2 Balance, having a capacity of about 100 g with aminimum sensitivity of 0.1 g.7. Sampling7.1 The sample presented for analysis should be larg
20、eenough to make possible the selection of a representativeportion for testing. Each run will require approximately 0.5 gfor each cubic centimetre of tube capacity . Examine for anyindication of non-homogeneity such as oil separation, phasechanges, or gross contamination. If any abnormal conditionsar
21、e found, obtain a new sample.7.2 The sample temperature at time of loading is to bebetween 15C and 35C.8. Preparation of Apparatus8.1 Inspect the centrifuge unit paying particular attention tothe cleanliness of the rotor which will be unbalanced by anysurface deposits.8.2 Examine the required number
22、 of tubes to be used for thetest, rejecting any with surface scratches or imperfections.9. Procedure9.1 For each grease, two centrifuge tubes are required. Newtubes must be used for each test and they must be handled withcare to avoid scratches.9.1.1 Determine the total volume, V, in cubic centimetr
23、es, ofeach tube by filling with water and then pouring into agraduated cylinder and measuring.9.1.2 Measure the inside diameter, d, in millimetres with avernier caliper.9.2 Take grease samples from the container without includ-ing any free oil found on the grease surface.9.3 Charge each tube with ap
24、proximately 0.5 g of grease foreach cubic centimeter of tube capacity (example:7gofgreasein a tube of 14 cm3) taking care that the difference in mass ofeach does not exceed 0.3 g to minimize centrifuge imbalance.9.4 Place the tubes in diametrically opposite compartmentsif all rotor compartments are
25、not used. Always use evennumbers of tubes.9.5 The centrifuge lid must always be closed when the rotoris turning. The rotor should never be touched while rotating.9.6 Operate the centrifuge at a G value of 1000 for 3 min toeliminate any trapped air bubbles in the grease charge.9.7 Measure the distanc
26、e, a, in millimetres from the top ofthe test tube to the closest point on the grease surface as shownin Fig. 1, and calculate the grease volume as in 10.1.9.8 Replace the tubes in the rotor head, close the lid, andbring the speed up to a relative acceleration, G, of 36 000.Consult manufacturers inst
27、ructions for proper speed.9.9 At the end of the test interval, the rotor must come to acomplete stop before opening the lid.9.10 Measure the amount of oil separated as follows:9.10.1 Cover the mouth of the tube with a piece of hardrubber or plastic material and invert for 1 to 2 min or until allthe
28、oil flows to the top of the tube.9.10.2 Measure the height, b, of the separated oil in milli-metres, as shown in Fig. 2.9.11 Calculate the oil volume as indicated in 10.2.9.12 Calculate the percent of oil separated from the greaseas indicated in 10.3.9.13 If the test is to be continued, return the t
29、ubes to theirrespective compartments in the centrifuge rotor. When thecovering over the tube mouth is removed all adhering oil mustbe returned to the tubes.9.14 Measure the amount of oil separation after one or moreof the following time periods: 6, 12, 24, 48, or 96 cumulative3Detailed discussion is
30、 found in Calistrat, M. M., Grease Separation underCentrifugal Forces, ASME Paper 75-PTG-3. Presented at the Joint ASLE-ASMELubrication Conference, Oct. 2123, 1975. FIG. 1 Measuring Grease VolumeD4425092hours of testing at a G value of 36 000. No more than 72 h ofinterruption is acceptable between t
31、wo test periods.9.15 The normal duration of a test is 24 cumulative hours.9.15.1 The test can be extended to 48 or 96 h if desired, butspecial reporting conditions prevail (see 11.4.2).10. Calculation10.1 Calculate the grease volume to the nearest cm3asfollows:Vg5 Vt2FSa 1d2 tan AD0.785 d2! 3 103G(3
32、)where:Vg= grease volume, cm3,Vt= tube volume, cm3(see 9.1.1),a = distance to grease surface, mm (see 9.7),d = tube inside diameter, mm (see 9.1.2), andA = angle of the rotor, in degrees. This angle is specifiedby the rotor manufacturer.10.2 Calculate the oil volume to the nearest cm3as follows:Vo5
33、0.785 d2b 3 103(4)where:Vo= separated oil volume, cm3, andb = height of the separated oil, mm (see 9.10).10.3 Calculate the amount of oil separated from the greaseto the nearest percent as follows:V 5VoVg3 100 (5)where:V = oil separation, in volume percent.11. Report11.1 The amount of oil separated
34、from a lubricating greasesubjected to centrifugal forces is a function of the G level, theamount of time under test, and the test temperature. Thus, toevaluate the resistance of a grease to separate the oil, thefollowing data are required:11.1.1 The oil separation, in volume percent (see 10.3).11.1.
35、2 The level of centrifugal acceleration, in G (see 3.1).11.1.3 The duration of the test, in hours.11.1.4 The test temperature, in degrees Celsius.11.2 In order to simplify the testing and reporting of the oilseparation from lubricating greases by centrifuging, the levelof centrifugal acceleration an
36、d the test temperature are main-tained constant, at a G value of 36 000 and 50C. Hence, theresistance of a grease to separate the oil under centrifugalforces is reported as the fraction K36.K36 5 V/H (6)where:V = oil separation, in volume percent (see 10.3), andH = accumulated time of testing in hou
37、rs (see 9.13).The fraction K36 should not be reduced, and the values ofboth V and H should be reported.11.3 The results of two tubes filled with the same grease(see 9.3) are averaged for reporting purposes.11.4 The values for V and H in Eq 6 are those at the time theoil separation stabilizes. This i
38、s defined as the time at which theoil separation increases by less than 10 % between twoconsecutive readings.11.4.1 If the oil separation does not stabilize before the 24 htest, the 24 h test results are used for reporting.11.4.2 If the testing is extended beyond the 24 cumulativehours, the same con
39、ditions in 11.4 apply, except more than 24h can be used. Examples of calculations can be found inAppendix X1.12. Precision and Bias412.1 PrecisionWhen run under the conditions stated inthe test method, the precision, as determined by statisticalexamination of interlaboratory results is as follows:12
40、.1.1 RepeatabilityThe difference between successivetest results, obtained by the same operator with the sameapparatus under constant operating conditions on identical testmaterial, would in the long run, in the normal and correctoperation of the test method, exceed 4.8 percentage points (ofthe value
41、 of V, 10.3) only in one case in twenty.12.1.2 ReproducibilityThe difference between two singleand independent results, obtained by different laboratories onidentical test material, would in the long run, in the normal andcorrect operation of test method, exceed 18.7 percentage points(of the value V
42、, 10.3) only in one case in twenty.12.2 BiasThe procedure in this test method has no biasbecause the value of K36 can be defined only in terms of thetest method.13. Keywords13.1 centrifuge; grease; lubricating grease; oil separation4Supporting data have been filed at ASTM International Headquarters
43、and maybe obtained by requesting Research Report RR: D02-1185.FIG. 2 Measuring Separated OilD4425093APPENDIX(Nonmandatory Information)X1. EXAMPLES OF CALCULATIONSX1.1 Examples for 24 h TestsCumulative hours, H 61224Oil separation, V 30 32 32K36 = 30/6, because V increased by less than 10 % between t
44、he 6 and 12 htests.Cumulative hours, H 61224Oil separation, V 30 35 38K36 = 35/12, because V increased by 17 % between the 6 h and 12 h test, butonly 8.5 % between the 12 and 24 h tests.Cumulative hours, H 61224Oil separation, V 30 35 42K36 = 42/24, because the oil separation did not stabilize befor
45、e the 24 h test.X1.2 Examples for Tests Exceeding 24 hCumulative hours, H 6 12244896Oil separation, V 30 35 42 44 44K36 = 42/24, because V increased by less than 10% between the 24 h and 48h tests.Cumulative hours, H 6 12244896Oil separation, V 30 35 42 47 48K36 = 47/48, because V increased by less
46、than 10% between the 48 h and 96h tests.Cumulative hours, H 6 12244896Oil separation, V 30 35 42 47 53K36 = 53/96, because the oil separation did not stabilize before the 96 h test.SUMMARY OF CHANGESSubcommittee D02.G0.03 has identified the location of selected changes to this standard since the las
47、t issue(D 442597(2002) that may impact the use of this standard.(1) Removed figure references to obsolete equipment in 6.1.2and 6.1.3.(2) Deleted original Figs. 1 and 2.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin
48、this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must
49、 be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 10
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