Standard Test Method for Measuring Viscosity at …

1 Designation: D 4683 04An American National StandardStandard Test Method forMeasuring Viscosity at high Shear Rate and HighTemperature by Tapered Bearing Simulator1 This Standard is issued under the fixed designation D 4683; 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 (e) indicates an editorial change since the last revision or Standard has been approved for use by agencies of the Department of Scope* This test Method covers the laboratory determination ofthe Viscosity of engine oils at 150 C and 13106s 1shear rateusing a tapered bearing simulator-viscometer (TBS Viscom-eter)2equipped with a refined thermoregulator system.

2 OlderTBS units not so equipped must use Test Method D 4683 The Newtonian calibration oils used to establish this testmethod cover the range from approximately to cP(mPa s) at 150 The non-Newtonian reference oil used to establish thistest Method has a Viscosity of approximately cP (mPa s) at150 C and a shear rate of 13106s Applicability to petroleum products other than engineoils has not been determined in preparing this test This test Method uses the centipoise (cP) as the unit ofviscosity. For information on the equivalent SI unit, themillipascal second (mPa s) is shown in Standard does not purport to address all of thesafety concerns, if any, associated with its use.

3 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 Referenced Standards:3D 4741 Test Method for Measuring Viscosity at high Tem-perature and high Shear Rate by Tapered-Plug ViscometerD 5481 Test Method for Measuring Apparent Viscosity atHigh-Temperature and high -Shear Rate by Multicell Cap-illary Viscometer3. the mass per unit volume. In the SI, the unitof density is the kilogram per cubic metre, but for practical usea submultiple is more convenient.

4 The gram per cubic centi-metre is 103kg/m3and is customarily oil or fluid an oil or fluid that at a giventemperature exhibits a constant Viscosity at all shear rates orshear oil or fluid an oil or fluid that exhib-its a Viscosity that varies with changing shear stress or rate the velocity gradient in fluid flow. The SIunit for shear rate is the reciprocal second (s-1). stress the motivating force per unit area forfluid flow. Theareais the area under the ratio between the applied shear stressand rate of shear. It is sometimes called the coefficient ofdynamic Viscosity .

5 This coefficient is thus a measure of theresistance to flow of the liquid. In the SI the unit of viscosityis the pascal second; for practical use, a submultiple, millipas-cal second, is more convenient. The centipoise is 1 mPa s andis customarily Viscosity the determined Viscosity ob-tained by this test Viscosity the ratio of the Viscosity to thedensity of the liquid. It is a measure of the resistance to flow ofa liquid under gravity. In the SI the unit of kinematic viscosityis the metre squared per second; for practical use, a submultiple(millimetre squared per second) is more convenient.

6 Thecentistoke (cSt) is 1 mm2/s and is customarily of Terms Specific to This Standard :1 This test Method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of on Flow edition approved Feb. 1, 2004. Published March 2004. Originallyapproved in 1987. Last previous edition approved in 1996 as D 4683 sole source of supply of the apparatus known to the committee at this timeis Tannas Co., 4800 James Savage Rd., Midland, MI 48642. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters.

7 Your comments will receive careful consideration at a meeting of theresponsible technical committee1, which you may referenced ASTM standards, visit the ASTM website, , orcontact ASTM Customer Service at ForAnnual Book of ASTMS tandardsvolume information, refer to the Standard s Document Summary page onthe ASTM *A Summary of Changes section appears at the end of this ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United oils2 Newtonian oils used to establish thereference framework of Viscosity versus torque from which isdetermined the test oil position the rotor height when in rubbingcontact with the oil2 an oxidatively stable Newtonian oil usedto minimize deposits on the rotor/stator operating surfaceswhen the instrument is held for long periods of time atoperating temperatures of 150 C at which other oils may inreasonably short time decompose and leave reference oil2 a specially selectednon-Newtonian reference oil

8 Required to establish the propergap between the rotor and stator to produce an operating shearrate of 13106s torque intersection, Rti the rotor positionon the micrometer defined by the intersection of two straightlines. These are generated by the reciprocal indicated torqueversus rotor height for the non-Newtonian NNR-03 and theNewtonian R-400. The intersection indicates the rotor height atwhich the rotor/stator cell will generate 13106s 1shear height (rotor position) the vertical position ofthe rotor relative to the stator and measured by the For most instruments, a mechanicalmicrometer is used; the micrometer readingincreasesas therotor is lowered and approaches the stator.

9 However, if anelectronic micrometer is used, the micrometer readingde-creaseswhen the rotor is position the rotor position with the rotor above the contact oil any oil for which apparent Viscosity is to Summary of Test A motor drives a tapered rotor that is closely fitted insidea matched stator. The rotor exhibits a reactive torque responsewhen it encounters a viscous resistance from an oil that fills thegap between the rotor and stator. Two oils, a calibration oil anda non-Newtonian reference oil, are used to determine the gapdistance between the rotor and stator so that a shear rate of13106s 1is maintained.

10 Additional calibration oils are usedto establish the Viscosity /torque relationship which is requiredfor the determination of the apparent Viscosity of test oils at150 Significance and Viscosity at the shear rate and temperature of this testmethod is thought to be representative of the conditionencountered in the bearings of automotive engines in The importance of Viscosity at these conditions toengine lubrication has been addressed in many Bearing Simulator-Viscometer2(Fig. 1) aviscometer consisting of a synchronous two-speed motor thatdrives a slightly tapered bearing in a matched stator (Fig.)