ASTM D5481-13(2020)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D5481 − 13 (Reapproved 2020)
Standard Test Method for
Measuring Apparent Viscosity at High-Temperature and
High-Shear Rate by Multicell Capillary Viscometer
This standard is issued under the fixed designation D5481; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Severaldifferentconfigurationsofcapillaryviscometershavebeensuccessfullyusedformeasuring
the viscosity of engine oils at the high shear rates and high temperatures that occur in engines. This
test method covers the use of a single apparatus at a single temperature and single shear rate to
achieve greater uniformity and improved precision.
1. Scope 1.2.2 Pounds per square inch (psi) is a non-SI unit of
pressure that is approximately equal to 6.895 kPa. These units
1.1 This test method covers the laboratory determination of
areprovidedforinformationonlyin6.1.1,7.3,9.1.2.1,andthe
high-temperaturehigh-shear(HTHS)viscosityofengineoilsat
tables.
a temperature of 150°C using a multicell capillary viscometer
1.3 This standard does not purport to address all of the
containing pressure, temperature, and timing instrumentation.
safety concerns, if any, associated with its use. It is the
The shear rate for this test method corresponds to an apparent
responsibility of the user of this standard to establish appro-
shear rate at the wall of 1.4 million reciprocal seconds
−1 3
priate safety, health, and environmental practices and deter-
(1.4×10 s ). Thisshearratehasbeenfoundtodecreasethe
mine the applicability of regulatory limitations prior to use.
discrepancy between this test method and other high-
temperature high-shear test methods (Test Methods D4683
1.4 This international standard was developed in accor-
and D4741) used for engine oil specifications. Viscosities are dance with internationally recognized principles on standard-
determined directly from calibrations that have been estab-
ization established in the Decision on Principles for the
lished with Newtonian oils with nominal viscosities from Development of International Standards, Guides and Recom-
1.4mPa·s to 5.0 mPa·s at 150°C. The precision has only been mendations issued by the World Trade Organization Technical
determined for the viscosity range 1.45mPa·s and 5.05 mPa·s Barriers to Trade (TBT) Committee.
at 150 °C for the materials listed in the precision section.
2. Referenced Documents
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this 2.1 ASTM Standards:
standard.
D4683Test Method for Measuring Viscosity of New and
Used Engine Oils at High Shear Rate and High Tempera-
1.2.1 ThecentiPoise(cP)isanon-SImetricunitofviscosity
ture by Tapered Bearing Simulator Viscometer at 150°C
that is numerically equal to the milliPascal-second (mPa·s).
D4741Test Method for Measuring Viscosity at High Tem-
peratureandHighShearRatebyTapered-PlugViscometer
D6300Practice for Determination of Precision and Bias
This test method is under the jurisdiction of ASTM Committee D02 on
Data for Use in Test Methods for Petroleum Products,
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Liquid Fuels, and Lubricants
Subcommittee D02.07 on Flow Properties.
Current edition approved May 1, 2020. Published June 2020. Originally
D6708Practice for StatisticalAssessment and Improvement
approved in 1993. Last previous edition approved in 2013 as D5481–13. DOI:
of Expected Agreement Between Two Test Methods that
10.1520/D5481-13R20.
Purport to Measure the Same Property of a Material
Manning, R. E., and Lloyd, W. A., “Multicell High Temperature High-Shear
Capillary Viscometer,” SAE Paper 861562. Available from Society of Automotive
Engineers (SAE), 400 Commonwealth Dr., Warrendale, PA15096-0001, www.sae-
.org.
3 4
Girshick, F., “Non-Newtonian Fluid Dynamics in High Temperature High For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Shear Capillary Viscometers,” SAE Paper 922288. Available from Society of contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Automotive Engineers (SAE), 400 Commonwealth Dr., Warrendale, PA 15096- Standards volume information, refer to the standard’s Document Summary page on
0001, www.sae.org. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5481 − 13 (2020)
3. Terminology Newtonian). The shear stress at the capillary wall may be
calculated as follows:
3.1 Definitions:
Z 5PR/2L (2)
3.1.1 apparent viscosity, n—viscosity of a non-Newtonian
liquid determined by this test method at a particular shear rate
where:
and shear stress.
Z = shear stress (Pa),
3.1.2 density, n—massperunitvolumeofthetestliquidata P = pressure drop (in Pa),
R = capillary radius, and
given temperature.
L = capillary length (in units consistent with R).
3.1.2.1 Discussion—In SI notation, the unit of density is the
3.1.8 viscosity, n—ratio of applied shear stress and the
kilogrampercubicmetre.However,forpracticaluse,gramper
cubic centimetre is customarily used and is equivalent to resulting rate of shear.
3 3
3.1.8.1 Discussion—It is sometimes called dynamic or ab-
10 kg/m .
soluteviscosity.Viscosityisameasureoftheresistancetoflow
3.1.3 kinematic viscosity, n—the ratio of the viscosity to the
of the liquid at a given temperature. In SI the unit of viscosity
density of the fluid.
is the Pascal second (Pa·s), often conveniently expressed as
3.1.3.1 Discussion—Kinematic viscosity is a measure of a
milliPascal second (mPa·s), which has the English system
fluid’s resistance to flow under the force of gravity. In the SI,
equivalent of the centiPoise (cP).
the unit of kinematic viscosity is the metre squared per second
3.2 Definitions of Terms Specific to This Standard:
(m /s); for practical use, a submultiple (millimetre squared per
3.2.1 calibration oils—those oils used for establishing the
second, mm /s) is more convenient. The centistoke (cSt) is
instrument’s reference framework of apparent viscosity versus
1mm /s and is often used.
pressure drop from which the apparent viscosities of the test
3.1.4 Newtonian oil or liquid, n—an oil or liquid that at a
oils are determined.
giventemperatureexhibitsaconstantviscosityatallshearrates
3.2.1.1 Discussion—Calibration oils, which are Newtonian
or shear stresses. 5
fluids, are available commercially or can be blended by the
user.
3.1.5 non-Newtonian oil or fluid, n—an oil or liquid that
exhibits a viscosity that varies with changing shear rate or
3.2.2 test oil—any oil for which the apparent viscosity is to
shear stress.
be determined by the test method.
3.1.6 shear rate—velocity gradient in liquid flow in milli- 3.2.3 viscometric cell—that part of the viscometer compris-
ing all parts which may be wet by the test sample, including
metres per second per millimetre (mm/s per mm) resulting
fromappliedshearstress;theSystemInternational(SI)unitfor exit tube, working capillary, fill tube, pressure/exhaust
–1
connection, plug valve, and fill reservoir.
shear rate is reciprocal seconds, s .
3.1.6.1 Discussion—The velocity gradient in the Multi-Cell
4. Summary of Test Method
Capillary Viscometer varies across the capillary annulus from
a maximum at the wall of the capillary to zero at the center of
4.1 The viscosity of the test oil in any of the viscometric
thecapillaryannulus.Assumingaparabolicflowprofileacross
cells is obtained by determining the pressure required to
thecapillary,theapparentshearrateatthecapillarywallcanbe achieve a flow rate corresponding to an apparent shear rate at
6 −1
calculated as follows:
thewallof1.4×10 s .Thecalibrationofeachcellisusedto
3 determine the viscosity corresponding to the measured pres-
S 54V/πR t (1)
a
sure.
where:
4.2 Each viscometric cell is calibrated by establishing the
−1
S = apparent shear rate (at the wall, s ),
a
relationship between pressure and flow rate for a series of
V = volume of fluid (mm ) passed through the capillary in
Newtonian oils of known viscosity.
time t (s), and
R = capillary radius (mm).
5. Significance and Use
S is precise for Newtonian liquids which generate a
a
5.1 Viscosity is an important property of fluid lubricants.
parabolic flow profile but may be approximate for non-
The viscosity of all fluids varies with temperature. Many
Newtonian liquids that do not necessarily generate a para-
common petroleum lubricants are non-Newtonian: their vis-
bolic flow profile.
cosity also varies with shear rate. The usefulness of the
3.1.7 shear stress, n—forceperunitareacausingliquidflow
viscosity of lubricants is greatest when the viscosity is mea-
over the area where viscous shear is being caused; in SI, the
sured at or near the conditions of shear rate and temperature
unit of shear stress is the Pascal (Pa).
that the lubricants will experience in service.
3.1.7.1 Discussion—In a capillary viscometer, the signifi-
cant shear stress is at the wall of the capillary.That is, the total
The sole source of supply known to the committee at this time is Cannon
force acting on the area of the capillary annulus divided by the
Instrument Co., 2139 High Tech Rd., State College, PA16803. If you are aware of
insideareaofthecapillarythroughwhichtheliquidflows.The
alternative suppliers, please provide this information to ASTM International
shear stress at the wall does not depend on the nature of the
Headquarters.Your comments will receive careful consideration at a meeting of the
liquid (that is, whether the liquid is Newtonian or non- responsible technical committee, which you may attend.
D5481 − 13 (2020)
5.2 The conditions of shear rate and temperature of this test 7.3 Carbon Dioxide or Nitrogen Cylinder, with reducer
method are thought to be representative of those in the bearing valve having a maximum pressure of at least 3500kPa
of automotive engines in severe service. (~500psi).
5.3 Many equipment manufacturers and lubricant specifica-
8. Sampling
tionsrequireaminimumhigh-temperaturehigh-shearviscosity
6 −1
8.1 Arepresentative sample of test oil, free from suspended
at 150°C and 10 s . The shear rate in capillary viscometers
solid material and water, is necessary to obtain valid results.
variesacrosstheradiusofthecapillary.Theapparentshearrate
When the sample is suspected to contain suspended material,
at the wall for this test method is increased to compensate for
filter with about 10µm filter paper.
the variable shear rate.
5.4 This test was evaluated in an ASTM cooperative pro-
9. Calibration and Standardization
gram.
9.1 Calibration:
6. Apparatus 9.1.1 The volume and capillary diameter of each viscomet-
ric cell in the instrument is provided by the manufacturer, and
6.1 Multi-Cell Capillary High-Temperature High-Shear
5 the nominal flow time, t , corresponding to an apparent shear
o
(HTHS) Viscometer, consisting of several viscometer cells in a
6 −1
rate at the wall of 1.4×10 s is calculated by the manufac-
temperature-controlled block and including means for control-
turer using the following equation:
ling and measuring temperature and applied pressure and for
6 3
t 54V/1.4*10 πR (3)
timing the flow of a predetermined volume of test oil. Each
o
viscometric cell contains a precision glass capillary and means
where symbols are defined as in 3.1.6.
for adjusting the test oil volume to the predetermined value.
9.1.2 Using a minimum of four Newtonian calibration oils
6.1.1 The Multi-Cell Capillary HTHS viscometer has the
covering the viscosity range from 1.5mPa·s to 5 mPa·s at
following typical dimensions and specifications:
150°C, determine the relationship between pressure and flow
Diameter of capillary 0.15 mm
rate for each viscometric cell. The pressure should be adjusted
Length of capillary 15 mm to 18 mm
for each calibration oil such that the measured flow time is
Temperature control 150 °C ± 0.1 °C
Pressure range 350 kPa to 3500 kPa (~50 to within 62% of the nominal flow time, t . Make three
o
500 psi)
determinations for each oil in each cell. Follow the instrument
Pressure control ±1 %
supplier’s documentation for using the software “High Shear
Sample volume 7 mL ± 1 mL
Viscosity Calculator” to record these results.
6.1.2 Thethermometerformeasuringthetemperatureofthe
9.1.2.1 The following relationship can be used to express
block is a preset digital resistance thermometer. The accuracy
the data:
of this thermometer may be checked by means of a special
thermowell and calibrated thermometer whose accuracy is C t
η 5 C ·t·P 2 · 11C · 1 2 (4)
F G F S D G
i 1 3
t t
60.1°C or better. See manufacturer’s recommendations for
o
procedure.
where:
η = intermediate viscosity, mPa·s,
i
7. Reagents and Materials
t = flow time, s,
7.1 NewtonianOils, havingnominalcertifiedviscositiesof
P = pressure, kPa, and
1.5mPa·s to 7.0 mPa·s at 150°C. See Table 1.
C,C,C = coefficients specific to each viscometric cell.
1 2 3
7.2 Non-Newtonian Reference Sample, having a certified
9.1.2.2 Coefficient C is specific to the units in which
6 −1
viscosity at 150 °C and 10 s .
pressure is expressed, as well as to each cell. Coefficient C
will be essentially constant over the relatively narrow range of
shear rates and viscosities of interest in measurement of the
high-temperature viscosity of automotive engine oil. In more
Supporting data have been filed atASTM International Headquarters and may
general applications, C may not be constant for all values of
beobtainedbyrequestingResearchReportRR:D02-1767.ContactASTMCustomer
Reynolds Number.
Service at service@astm.org.
9.1.2.3 Intermediate viscosity equals viscosity for the cali-
bration oils.
TABLE 1 Calibration Oils
9.1.2.4 Use the suppliers “High ShearViscosity Calculator”
Approximate Approximate Pressure
A
software to determine the calibration coefficients for each
Viscosity at 150 °C for Test Method
Calibration Oil
(mPa·s) psi kPa viscometric cell.
9.1.2.5 Alternatively, AnnexA1 describes the procedure for
HT22 1.5 190 1310
HT39 2.0 225 1550
determining coefficients C , C , and C .
1 2 3
HT75 2.7 290 2000
HT150 3.7 375 2590
9.2 Stability of Viscosity Calibration—Checkthestabilityof
HT240 5.0 480 3310
the calibration by running a calibration oil in the same manner
B
HT390 7.0 645 4450
asatestoilwouldberun.Thisshallbedonenolessfrequently
A
Consult the supplier for specific values.
B than before each new series of runs and every twentieth run.
Consult the supplier for use in instruments with pressure limiters of 525 psi.
The non-Newtonian calibration oil should
...