1、Designation: D5481 10Standard Test Method forMeasuring Apparent Viscosity at High-Temperature andHigh-Shear Rate by Multicell Capillary Viscometer1This standard is issued under the fixed designation D5481; the number immediately following the designation indicates the year oforiginal adoption or, in
2、 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.INTRODUCTIONSeveral different configurations of capillary viscometers have been successfully us
3、ed 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. Scope*1.1 This test method cover
4、s 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 an apparentshear rate at the wall
5、 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-tions that have been established
6、with Newtonian oils withviscosities from 2 to 5 mPa-s at 150C.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.2.1 The centiPoise (cP) is a non-SI metric unit of viscositythat is numerically equal to the milliPascal-second
7、(mPa-s).1.2.2 Pounds per square inch (psi) is a non-SI unit ofpressure that is approximately equal to 6.895 kPa. These unitsare provided for information only in 6.1.1, 7.3, 9.1.2.1, and thetables.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use
8、. 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:4D4683 Test Method for Measuring Viscosity of New andUsed Engine Oils at High
9、 Shear Rate and High Tempera-ture by Tapered Bearing Simulator Viscometer at 150 CD4741 Test Method for Measuring Viscosity at High Tem-perature and High Shear Rate by Tapered-Plug Viscometer3. Terminology3.1 Definitions:3.1.1 apparent shear rate at the wallshear rate at the wallof the capillary cal
10、culated 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 = 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 determine
11、d viscosity obtainedby this test method.3.1.3 densitymass per unit volume.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 Aug. 1, 2010. Published S
12、eptember 2010. Originallyapproved in 1993. Last previous edition approved in 2004 as D548104. DOI:10.1520/D5481-10.2Manning, R. E., and Lloyd, W. A., “Multicell High Temperature High-ShearCapillary Viscometer,” SAE Paper 861562. Available from Society of AutomotiveEngineers (SAE), 400 Commonwealth D
13、r., Warrendale, PA 15096-0001, www.sae-.org.3Girshick, F., “Non-Newtonian Fluid Dynamics in High Temperature HighShear Capillary Viscometers,” SAE Paper 922288. Available from Society ofAutomotive Engineers (SAE), 400 Commonwealth Dr., Warrendale, PA 15096-0001, www.sae.org.4For referenced ASTM stan
14、dards, 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.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM Inte
15、rnational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.3.1 DiscussionIn the SI, the unit of density is thekilogram per metre cubed (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
16、 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 kinematic viscosity is the metre squared per second(m2/s); for practical use, a submultiple (millimetre squared persecond, mm2/s) i
17、s 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 shear stresses.3.1.6 non-Newtonian oil or fluidan oil or fluid that exhib-its a viscosity that varies with changing shear rate or sh
18、earstress.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 DiscussionThe derived unit of shear rate is veloc-ity divided by length. With the time in seconds and withconsis
19、tent 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 shear stress is the shear stress at the wall, that is, the totalforce acting on the cross section of the c
20、apillary 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 stress is the pascal(Pa). Mathematically, the shear stress at the wall of a capillaryviscometer is as fol
21、lows: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 the same location.3.1.9.1 DiscussionViscosity is sometimes called the coef-ficient of viscosity, or the
22、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, mPa-s) is more convenient.3.2 Definitions of Terms Specific to This Standard:3.2.1 calibration oilsthose oils used for est
23、ablishing theinstruments reference framework of apparent viscosity versuspressure drop from which the apparent viscosities of the testoils are determined.3.2.1.1 DiscussionCalibration oils, which are Newtonianfluids, are available commercially5or can be blended by theuser.3.2.2 test oilany oil for w
24、hich 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 wet by the test sample, includingexit tube, working capillary, fill tube, pressure/exhaust connec-tion, plug valve, and fill reservoir.4. Summary of
25、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 corresponding 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 me
26、asuredpressure.4.2 Each viscometric cell is calibrated by establishing therelationship between pressure and flow rate for a series ofNewtonian oils of known viscosity.5. Significance and Use5.1 Viscosity is an important property of fluid lubricants.The viscosity of all fluids varies with temperature
27、. Manycommon petroleum lubricants are non-Newtonian: their vis-cosity also varies with shear rate. The usefulness of theviscosity of lubricants is greatest 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 co
28、nditions of shear rate and temperature of this testmethod are thought to be representative of those in the bearingof automotive engines in severe service.5.3 Many equipment manufacturers and lubricant specifica-tions require a minimum high-temperature high-shear viscosityat 150C and 106s1. The shear
29、 rate in capillary viscometersvaries across the radius of the capillary. The apparent shear rateat the wall for this test method is increased to compensate forthe variable shear rate.35.4 This test was evaluated in an ASTM cooperative pro-gram.66. Apparatus6.1 High-Temperature High-Shear (HTHS)Visco
30、meter,5consisting of several viscometer cells in atemperature-controlled block and including means for control-ling and measuring temperature and applied pressure and fortiming the flow of a predetermined volume of test oil. Each5The sole source of supply known to the committee at this time is Canno
31、nInstrument Co., P.O. Box 16, State College, PA 16804. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.6Supporting da
32、ta have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1378.D5481 102viscometric 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
33、di-mensions and specifications:Diameter of capillary 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 resistan
34、ce thermometer. The accuracyof this thermometer may be checked by means of a specialthermowell and calibrated thermometer5whose accuracy is60.1C or better. See manufacturers recommendations forprocedure.7. Reagents and Materials7.1 Newtonian Oils,5having certified viscosities of 2 to 7mPa-s at 150C.
35、 See Table 1.7.2 Non-Newtonian Reference Sample,57having a certifiedviscosity at 150C and 106s1.7.3 Carbon Dioxide or Nitrogen Cylinder, with reducervalve having a maximum pressure of at least 3500 kPa (500psi).8. Sampling8.1 A representative sample of test oil, free from suspendedsolid material and
36、 water, is necessary to obtain valid results.When the sample is suspected to contain suspended material,filter with about 10-m filter paper.9. Calibration and Standardization9.1 Calibration:9.1.1 The volume and capillary diameter of each viscomet-ric cell is provided by the manufacturer, and the flo
37、w 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*106pR3(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 mPa-s
38、at 150C,determine the relationship between pressure and flow rate. Thepressure should be adjusted for each calibration oil such thatthe flow time is 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 express
39、the data:hi5FC1tP 2C2tGF1 1 C3S1 2ttoD G(4)where:hi= intermediate viscosity, mPa-s,t = flow time, s,P = pressure, kPa, andC1,C2,C3= coefficients specific to 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
40、be essentially constant over the relatively narrow range ofshear rates and viscosities of interest in measurement of thehigh-temperature viscosity of automotive engine oil. In moregeneral applications, C2may not be constant for all values ofReynolds Number.9.1.2.3 Intermediate viscosity equals visco
41、sity for the cali-bration oils.9.1.2.4 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 same manneras a test oil would be run. This shall be done no less frequen
42、tlythan 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 than therepeatability of the test (see 12.1). If it is out of limits, an
43、d 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 thoroughly for faults, includingforeign material in the capillary, veri
44、fy 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 thermometer inserted in the thermowell in thealuminum block.10. Procedure10.1 B
45、ring 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 temperature unlessuse is not anticipated for an extended period of time.10.2
46、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 open.) Inserta4to6-mL test sample, and close the plugvalve. Turn on the p
47、ressure (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 made. Turn off the pressure.TABLE 1 Calibration OilsCalibration OilAppro
48、ximateViscosityAApproximate Pressurefor Test Method(mPa-s) 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.D5481 10310.3 Chargea9to11-mL test sample into the viscometriccell by opening the plug valve, inserting
49、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 temperature 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 the nominal flow time, to(see9.1.1). Table 2 provides a gui
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