1、Designation: D 5481 04An American National StandardStandard Test Method forMeasuring Apparent Viscosity at High-Temperature andHigh-Shear Rate by Multicell Capillary Viscometer1This standard is issued under the fixed designation D 5481; the number immediately following the designation indicates the
2、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 reapproval.INTRODUCTIONSeveral different configurations of capillary visco
3、meters have been successfully used for measuringthe viscosity of engine oils at the high shear rates and high temperatures that occur in engines. Thistest method covers the use of a single apparatus2at a single temperature and single shear rate toachieve greater uniformity and improved precision.1.
4、Scope*1.1 This test method covers the laboratory determination ofhigh-temperature high-shear (HTHS) viscosity of engine oils ata temperature of 150C using a multicell capillary viscometercontaining pressure, temperature, and timing instrumentation.The shear rate for this test method corresponds to a
5、n apparentshear rate at the wall of 1.4 million reciprocal seconds(1.4 3 106s1).3This shear rate has been found to decrease thediscrepancy between this test method and other high-temperature high-shear test methods3used for engine oilspecifications. Viscosities are determined directly from calibra-t
6、ions that have been established with Newtonian oils withviscosities from 2 to 5 mPas at 150C.1.2 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 prac
7、tices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:4D 4683 Test Method for Measuring Viscosity at High ShearRate and High Temperature by Tapered Bearing SimulatorD 4741 Test Method for Measuring Viscosity at High Tem-perature and H
8、igh Shear Rate by Tapered Plug Viscometer3. Terminology3.1 Definitions:3.1.1 apparent shear rate at the wallshear rate at the wallof the capillary calculated for a Newtonian fluid, as follows:Sa5 4V/pR3t (1)where:Sa= apparent shear rate at the wall, s1,V = volume, mm3,R = capillary radius, mm, andt
9、= measured flow time, s.3.1.1.1 DiscussionThe actual shear rate at the wall willdiffer for a non-Newtonian fluid.3.1.2 apparent viscositythe determined viscosity obtainedby this test method.3.1.3 densitymass per unit volume.3.1.3.1 DiscussionIn the SI, the unit of density is thekilogram per metre cu
10、bed (kg/m3); the gram per cubic centi-metre (g/cm3) is often used. One kg/m3is 103g/cm3.3.1.4 kinematic viscositythe ratio of the viscosity to thedensity of the fluid.3.1.4.1 DiscussionKinematic viscosity is a measure of afluids resistance to flow under the force of gravity. In the SI,the unit of ki
11、nematic viscosity is the metre squared per second(m2/s); for practical use, a submultiple (millimetre squared persecond, mm2/s) is more convenient. The centistoke (cSt) is 1mm2/s and is often used.3.1.5 Newtonian oil or fluidan oil or fluid that exhibits aconstant viscosity at all shear rates or she
12、ar stresses.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.07 on Flow Properties.Current edition approved May 1, 2004. Published June 2004. Originallyapproved in 1993. Last previous edition app
13、roved in 2001 as D 548196 (2001).2Manning, R. E., and Lloyd, W. A., “Multicell High Temperature High-ShearCapillary Viscometer,” SAE Paper 861562. Available from Society of AutomotiveEngineers (SAE), 400 Commonwealth Dr., Warrendale, PA 15096-0001.3Girshick, F., “Non-Newtonian Fluid Dynamics in High
14、 Temperature HighShear Capillary Viscometers,” SAE Paper 922288. Available from Society ofAutomotive Engineers (SAE), 400 Commonwealth Dr., Warrendale, PA 15096-0001.4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual B
15、ook of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.6 non-Newt
16、onian oil or fluidan oil or fluid that exhib-its a viscosity that varies with changing shear rate or shearstress.3.1.7 shear ratethe spatial gradient of velocity in laminarflow; the derivative of velocity with respect to distance in adirection perpendicular to the direction of flow.3.1.7.1 Discussio
17、nThe derived unit of shear rate is veloc-ity divided by length. With the time in seconds and withconsistent units of length, shear rate becomes reciprocalseconds, or s1.3.1.8 shear stressforce per area of fluid in the direction offlow.3.1.8.1 DiscussionIn a capillary viscometer, the signifi-cant she
18、ar stress is the shear stress at the wall, that is, the totalforce acting on the cross section of the capillary divided by thearea of the inside surface of the capillary.The shear stress at thewall does not depend on the fluid properties (that is, Newtonianor non-Newtonian). The SI unit for shear st
19、ress is the pascal(Pa). Mathematically, the shear stress at the wall of a capillaryviscometer is as follows:Z 5 PR/2L (2)where:Z = shear stress, Pa,P = pressure drop, Pa,R = capillary radius, andL = capillary length in consistent units.3.1.9 viscositythe ratio between shear stress and shear rateat t
20、he same location.3.1.9.1 DiscussionViscosity is sometimes called the coef-ficient of viscosity, or the dynamic viscosity. It is a measure ofa fluids resistance to flow. In the SI, the unit of viscosity is apascal second (Pas); for practical use a submultiple (millipas-cal second, mPas) is more conve
21、nient. The centipoise (cP) is1 mPas and is often used.3.2 Definitions of Terms Specific to This Standard:3.2.1 calibration oilsthose oils used for establishing theinstruments reference framework of apparent viscosity versuspressure drop from which the apparent viscosities of the testoils are determi
22、ned.3.2.1.1 DiscussionCalibration oils, which are Newtonianfluids, are available commercially5or can be blended by theuser.3.2.2 test oilany oil for which the apparent viscosity is tobe determined by the test method.3.2.3 viscometric cellthat part of the viscometer compris-ing all parts which may be
23、 wet by the test sample, includingexit tube, working capillary, fill tube, pressure/exhaust connec-tion, plug valve, and fill reservoir.4. Summary of Test Method4.1 The viscosity of the test oil in any of the viscometriccells is obtained by determining the pressure required toachieve a flow rate cor
24、responding to an apparent shear rate atthe wall of 1.4 3 106s1. The calibration of each cell is usedto determine the viscosity corresponding to the measuredpressure.4.2 Each viscometric cell is calibrated by establishing therelationship between pressure and flow rate for a series ofNewtonian oils of
25、 known viscosity.5. Significance and Use5.1 Viscosity is an important property of fluid lubricants.The viscosity of all fluids varies with temperature. Manycommon petroleum lubricants are non-Newtonian: their vis-cosity also varies with shear rate. The usefulness of theviscosity of lubricants is gre
26、atest when the viscosity is mea-sured at or near the conditions of shear rate and temperaturethat the lubricants will experience in service.5.2 The conditions of shear rate and temperature of this testmethod are thought to be representative of those in the bearingof automotive engines in severe serv
27、ice.5.3 Many equipment manufacturers and lubricant specifica-tions require a minimum high-temperature high-shear viscosityat 150C and 106s1. The shear rate in capillary viscometersvaries across the radius of the capillary. The apparent shear rateat the wall for this test method is increased to compe
28、nsate forthe variable shear rate.35.4 This test was evaluated in an ASTM cooperative pro-gram.66. Apparatus6.1 High-Temperature High-Shear (HTHS)Viscometer,5consisting of several viscometer cells in atemperature-controlled block and including means for control-ling and measuring temperature and appl
29、ied pressure and fortiming the flow of a predetermined volume of test oil. Eachviscometric cell contains a precision glass capillary and meansfor adjusting the test oil volume to the predetermined value.6.1.1 The HTHS viscometer has the following typical di-mensions and specifications:Diameter of ca
30、pillary 0.15 mmLength of capillary 15 to 18 mmTemperature control 150 6 0.1CPressure range 350 to 3500 KPa (50 to 500 psi)Pressure control 61%Sample volume 7 6 1mL6.1.2 The thermometer for measuring the temperature of theblock is a preset digital resistance thermometer. The accuracyof this thermomet
31、er may be checked by means of a specialthermowell and calibrated thermometer7whose accuracy is60.1C or better. See manufacturers recommendations forprocedure.7. Reagents and Materials7.1 Newtonian Oils,7having certified viscosities of 2 to 7mPas at 150C. See Table 1.7.2 Non-Newtonian Reference Sampl
32、e,7having a certifiedviscosity at 150C and 106s1.5The sole source of supply known to the committee at this time is CannonInstrument Co., P.O. Box 16, State College, PA 16804. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments wi
33、ll receive careful consideration at a meeting of theresponsible technical committee1, which you may attend.6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D02-1378.D54810427.3 Carbon Dioxide or Nitrogen Cylinder, with reducerva
34、lve having a maximum pressure of at least 500 psi (3500 Pa).8. Sampling8.1 A representative sample of test oil, free from suspendedsolid material and water, is necessary to obtain valid results.When the sample is suspected to contain suspended material,filter with about 10-m filter paper.9. Calibrat
35、ion and Standardization9.1 Calibration:9.1.1 The volume and capillary diameter of each viscomet-ric cell is provided by the manufacturer, and the flow time, to,corresponding to an apparent shear rate at the wall of 1.4 3 106s1is calculated by the manufacturer using the followingequation:to5 4V/1.4*1
36、06pR3(3)where symbols are defined as in 3.1.1.9.1.2 Using a minimum of four Newtonian calibration oilscovering the viscosity range from 2 to 5 mPas (cP) at 150C,determine the relationship between pressure and flow rate. Thepressure should be adjusted for each calibration oil such thatthe flow time i
37、s within 620 % of the nominal flow time, to.Make three determinations for each oil in each cell.9.1.2.1 The following relationship can be used to expressthe data:h5FC1tP 2C2tGF1 1 C3S1 2ttoD G(4)where:h = viscosity, mPas,t = flow time, s,P = pressure, kPa or psi, andC1,C2,C3= coefficients specific t
38、o each viscometer cell.9.1.2.2 Coefficient C1is specific to the units in whichpressure is expressed, as well as to each cell. Coefficient C2will be essentially constant over the relatively narrow range ofshear rates and viscosities of interest in measurement of thehigh-temperature viscosity of autom
39、otive engine oil. In moregeneral applications, C2may not be constant for all values ofReynolds Number.9.1.2.3 Annex A1 describes the procedure for determiningcoefficients C1, C2, and C3.9.2 Stability of Viscosity CalibrationCheck the stability ofthe calibration by running a calibration oil in the sa
40、me manneras a test oil would be run. This shall be done no less frequentlythan before each new series of runs and every twentieth run.The non-Newtonian calibration oil should be run at leastmonthly. The calibration oil viscosity determined in this waymust not differ from the standard value by more t
41、han therepeatability of the test (see 12.1). If it is out of limits, and ifthe result is confirmed by a repeat run, look for the source ofthe trouble, rectify it, and repeat the entire calibration proce-dure, if necessary. Some possible steps to find the source of thetrouble are to check the system
42、thoroughly for faults, includingforeign material in the capillary, verify the fidelity of theoperating procedure, and accuracy of temperature control, andreadout.9.3 Stability of Temperature CalibrationCheck the cali-bration of the temperature sensor at least once a year using astandardized thermome
43、ter inserted in the thermowell in thealuminum block.10. Procedure10.1 Bring the viscometer to the test temperature and allowtest temperature to stabilize for at least 30 min. Because theviscometer uses only a small amount of electrical power, it maybe desirable to leave the viscometer at test temper
44、ature unlessuse is not anticipated for an extended period of time.10.2 Flush the previous sample with 4 to 6 mL of the newtest sample. Open the plug valve. (WarningAlways keep theplug valve closed except when charging or adjusting thevolume of sample; NEVER turn on the pressure with the plugvalve op
45、en.) Inserta4to6-mL test sample, and close the plugvalve. Turn on the pressure (it is not necessary to adjust thepressure from the previous run) until the flush sample haspassed through the capillary to waste. It is not necessary toachieve temperature equilibrium since no time measurement isbeing ma
46、de. Turn off the pressure.10.3 Chargea9to11-mL test sample into the viscometriccell by opening the plug valve, inserting the test sample, andthen closing the plug valve.10.4 Repeat 10.2 and 10.3 for each of the viscometric cells.10.5 Allow 15 min for the test sample to attain 150 6 0.1C.10.6 After t
47、emperature equilibrium has been established,ensure that the plug valve is closed on each cell and makemeasurement of efflux time and pressure as follows:10.6.1 From the calibration of the viscometric cell and theexpected viscosity of the sample (if known), estimate therequired pressure to achieve th
48、e nominal flow time, to(see9.1.1). Table 2 provides a guide for setting pressure if the SAEviscosity grade is known.Adjust the pressure in the ballast tankto this value within 61 %; allow approximately 10 s for thispressure to stabilize.10.6.2 Reset the timer to zero.10.6.3 Open the plug valve and w
49、ithdraw excess sample byvacuum through the filling tube until no more liquid is beingwithdrawn. Immediately close plug valve and immediatelyproceed to 10.6.4.TABLE 1 Calibration OilsCalibration OilApproximateViscosityAApproximate Pressure for Test Method(mPas) psi kPaHT39 2.0 225 1500HT75 2.7 290 2000HT150 3.7 375 2500HT240 5.0 480 3300HT390 7.0 645 4500AConsult the supplier for specific values.TABLE 2 Approximate Pressure for Test MethodSAE GradePressurepsi kPa20 225 150030 250 175040 300 210050 350 2450D548104310.6.4 Turn on th
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