ASTM_D_6821_-_14.pdf

Designation:D682114Standard Test Method forLow Temperature Viscosity of Drive Line Lubricants in aConstant Shear Stress Viscometer1This standard is issued under the fixed designation D6821;the number immediately following the designation indicates the year oforiginal adoption or,in 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 the measurement of the viscos-ity of drive line lubricants(gear oils,automatic transmissionfluids,and so forth)with a constant shear stress viscometer attemperatures from 40 C to 10 C after a prescribed preheatand controlled cooling to the final test temperature.Theprecision is stated for test temperatures from 40 C to 26 C.1.2 The applicability of this particular test method to petro-leum products other than drive line lubricants has not beendetermined.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 This standard uses the SI based unit of milliPascalsecond(mPas)for viscosity which is equivalent to centiPoise(cP).1.4 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D2983 Test Method for Low-Temperature Viscosity of Lu-bricants Measured by Brookfield ViscometerD3829 Test Method for Predicting the Borderline PumpingTemperature of Engine OilD4684 Test Method for Determination of Yield Stress andApparent Viscosity of Engine Oils at Low TemperatureD6896 Test Method for Determination of Yield Stress andApparent Viscosity of Used Engine Oils at Low Tempera-tureE563 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 17025 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 the use of this test method.3.1.2 Digital Contact 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 temperature from the measured quantity,andprovides a digital output or display,or both,of the temperature.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 thermometers(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 agiven 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 approved July 1,2014.Published July 2014.Originally approvedin 2002.Last previous edition approved in 2012 as D6821 12.DOI:10.1520/D6821-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,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 Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.5 shear rate,nthe velocity gradient in fluid flow.3.1.5.1 DiscussionFor a Newtonian fluid in a concentriccylinder rotary viscometer in which the shear stress is mea-sured at the inner cylinder surface(such as the apparatusdescribed in 6.1),and ignoring any end effects,the shear rate isgiven 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 radius,mm,Rr=rotor radius,mm,andt=time for one revolution of the rotor,s.For the specific apparatus being described in 6.1.1,533t(3)3.1.6 shear stress,nthe