1、Designation:D9102(Reapproved 2012)Standard Test Method forPrecipitation Number of Lubricating Oils1,2This standard is issued under the fixed designation D91;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.An
2、umber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method covers the determination of the pre-cip
3、itation number of steam cylinder stocks and black oils,andcan be used for other lubricating oils.1.2 The values stated in acceptable SI units are to beregarded as the standard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibili
4、ty 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:3D4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sa
5、mpling of Petroleum andPetroleum Products3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 ASTM precipitation number,of lubricating oils,nthenumber of millilitres of precipitate formed when 10 mL oflubricating oil are mixed with 90 mL of ASTM precipitationnaphtha,and centrifuged
6、under the conditions of the test.4.Significance and Use4.1 Fully refined petroleum oils normally contain no naph-tha insoluble material.Semirefined or black oils frequentlycontain some naphtha insoluble material(sometimes referredto as asphaltenes).This test measures the amount of naphthainsoluble m
7、aterial in the oil.This quantity is reported as theprecipitation number.5.Apparatus5.1 Centrifuge Tube,cone-shaped,conforming to the di-mensions given in Fig.1,and made of thoroughly annealedglass.The graduations,numbered as shown in Fig.1,shall beclear and distinct,and the mouth shall be constructe
8、d in a shapesuitable for closure with a cork.Scale-error tolerances andsmallest graduations between various calibration marks aregiven in Table 1 and apply to calibrations made with air-freewater at 20C.5.2 Centrifuge,meeting all the safety requirements fornormal use and capable of whirling two or m
9、ore filledcentrifuge tubes at a speed which can be controlled to give arelative centrifugal force(rcf)between 600 and 700 at the tipof the tubes.The revolving head,trunnion rings,and trunnioncups,including the rubber cushion,shall be soundly con-structed to withstand the maximum centrifugal force ca
10、pable ofbeing delivered by the power source.The trunnion cups andcushions shall firmly support the tubes when the centrifuge isin motion.The centrifuge shall be enclosed by a metal shield orcase strong enough to eliminate danger if any breakage occurs.Calculate the speed of the rotating head by mean
11、s of thefollowing equation:rpm5 1337=rcf/d(1)where:rcf=relative centrifugal force,andd=diameter of swing,in mm,measured between tips ofopposite tubes when in rotating position.Table 2 shows the relationship between diameter swing,rcf,and revolutions per minute.6.Reagent6.1 Hexanes,Reagent Grade.(War
12、ningExtremelyflammable,harmful if inhaled.)7.Sampling7.1 For sampling techniques,see Practices D4057 or Prac-tice D4177.1This 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 Lubrican
13、ts.Current edition approved Nov.1,2012.Published November 2012.Originallyapproved in 1921.Last previous edition approved in 2007 as D91 02(2007).DOI:10.1520/D0091-02R12.2This test method has been adopted for use by government agencies to replaceMethod 3101 of Federal Test Method Standard No.791b.3Fo
14、r 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West C
15、onshohocken,PA 19428-2959.United States1 8.Procedure8.1 Add 10 6 1 mL of the oil to be tested in each of twoclean,dry centrifuge tubes at room temperature.Fill each tubeto the 100-mL mark with hexanes and close tightly with asoftened cork(not a rubber stopper).Then invert each tube atleast 20 times,
16、allowing the liquid to drain thoroughly from thetapered tip of the tube each time.Place the tubes in a water bathat 32 to 35C for 5 6 1 min.Momentarily remove the corks torelieve any pressure,and invert each tube again at least 20times exactly as before.The success of this method depends toa large degree upon having a thoroughly homogeneous mixturewhich will drain quickly and completely from the tapered tipwhen the tube is inverted.8.2 Balance the two centrifuge tubes or pairs of tubes withtheir
