1、Designation:D689614Standard Test Method forDetermination of Yield Stress and Apparent Viscosity ofUsed Engine Oils at Low Temperature1This standard is issued under the fixed designation D6896;the number immediately following the designation indicates the year oforiginal adoption or,in the case of re
2、vision,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 the measurement of the yieldstress and viscosity of engine oils after cooling a
3、t controlledrates over a period of 43 h or 45 h to a final test temperature of20 C or 25 C.The precision is stated for test temperatures20 C and 25 C.The viscosity measurements are made at ashear stress of 525 Pa over a shear rate of 0.4 s-1to 15 s-1.Thistest method is suitable for measurement of vi
4、scosities rangingfrom 4000 mPas to 400 000 mPas,and is suitable for yieldstress measurements of 7 Pa to 350 Pa.1.2 This test method is applicable for used diesel oils.Theapplicability and precision to other used or unused engine oilsor to petroleum products other than engine oils has not beendetermi
5、ned.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3.1 ExceptionThis test method uses the SI based unit ofmilliPascal second(mPas)for viscosity which is equivalent tocentiPoise(cP).1.4 This standard does not purport to add
6、ress all of thesafety concerns,if any,associated with its use.It is theresponsibility 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:2D3829 Test Method
7、 for Predicting the Borderline PumpingTemperature of Engine OilD4684 Test Method for Determination of Yield Stress andApparent Viscosity of Engine Oils at Low TemperatureD5133 Test Method for Low Temperature,Low Shear Rate,Viscosity/Temperature Dependence of Lubricating OilsUsing a Temperature-Scann
8、ing TechniqueE563 Practice for Preparation and Use of an Ice-Point Bathas a Reference TemperatureE644 Test Methods for Testing Industrial Resistance Ther-mometersE1137 Specification for Industrial Platinum Resistance Ther-mometersE2877 Guide for Digital Contact Thermometers2.2 ISO Standards:3ISO 170
9、25 General Requirements for the Competence ofTesting and Calibration LaboratoriesISO Guide 34 General Requirements for the Competence ofReference Material Producers3.Terminology3.1 Definitions:3.1.1 apparent viscosity,nthe determined viscosity ob-tained by use of this test method.3.1.2 Digital Conta
10、ct Thermometer(DCT),nan electronicdevice consisting of a digital display and associated tempera-ture sensing probe.3.1.2.1 DiscussionThis device consists of a temperaturesensor connected to a measuring instrument;this instrumentmeasures the temperature-dependent quantity of the sensor,computes the t
11、emperature from the measured quantity,andprovides a digital output or display of the temperature,or both.The temperature sensing probe is in contact with the materialwhose temperature is being measured.This device is some-times referred to as a digital thermometer.NOTE1Portable electronic thermomete
12、rs(PET)is an acronym some-times used to refer to a subset of the devices covered by this definition.3.1.3 Newtonian oil or fluid,nan oil or fluid that at a giventemperature exhibits a constant viscosity at all shear rates orshear stresses.3.1.4 non-Newtonian oil or fluid,nan oil or fluid that at agi
13、ven temperature exhibits a viscosity that varies with chang-ing shear stress or shear rate.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.07 on Flow Properties.Current edition appr
14、oved July 1,2014.Published August 2014.Originallyapproved in 2003.Last previous edition approved in 2012 as D6896 12.DOI:10.1520/D6896-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume info
15、rmation,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harb
16、or Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.5 shear rate,nthe velocity gradient in fluid flow.Fora Newtonian fluid in a concentric cylinder rotary viscometer inwhich the shear stress is measured at the inner cylinder surface(such as the apparatus described in 6.1),and ignoring any endeffects,the shear rate is given as follows:52!Rs2Rs22 Rr2(1)54!Rs2tRs22 Rr2!(2)where:=shear rate at the surface of the rotor in reciprocalseconds,s-1,=angular velocity,rad/s,Rs=stator rad
