ASTM_D_91_-_02_2019.pdf

Designation:D9102(Reapproved 2019)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.Anumber 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-cipitation number of steam cylinder stocks and black oils,andcan be used for other lubricating oils.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:3D4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling 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 under the conditions of the test.4.Significance and Use4.1 Fully refined petroleum oils normally contain nonaphtha-insoluble material.Semirefined or black oils fre-quently contain some naphtha-insoluble material(sometimesreferred to as asphaltenes).This test measures the amount ofnaphtha-insoluble material in the oil.This quantity is reportedas the precipitation 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 constructed 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 20 C.5.2 Centrifuge,meeting all the safety requirements fornormal use and capable of whirling two or more filledcentrifuge tubes at a speed which can be controlled to give arelative centrifugal force(rcf)between 600 and 700 at the tipsof the tubes.The revolving head,trunnion rings,and trunnioncups,including the rubber cushion,shall be soundly con-structed to withstand the maximum centrifugal force capable 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 means of thefollowing equation:speed,r/min5 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.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.06 on Analysis of Liquid Fuels and Lubricants.Current edition approved May 1,2019.Published July 2019.Originally approvedin 1921.Last previous edition approved in 2017 as D91 02(2017).DOI:10.1520/D0091-02R19.2This test method has been adopted for use by government agencies to replaceMethod 3101 of Federal Test Method Standard No.791b.3For 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 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 6.Reagent6.1 Hexanes,Reagent Grade.(WarningExtremelyflammable,harmful if inhaled.)7.Sampling7.1 For sampling techniques,see Practice D4057 or PracticeD4177.8.Procedure8.1 Add 10 mL 6 1 mL of