ASTM D7945-14

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Designation: D7945 − 14
StandardTest Method for
Determination of Dynamic Viscosity and Derived Kinematic
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Viscosity of Liquids by Constant Pressure Viscometer
This standard is issued under the fixed designation D7945; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
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1.1 This test method covers the measurement of dynamic 2.1 ASTM Standards:
viscosityanddensityforthepurposeofderivationofkinematic D445 Test Method for Kinematic Viscosity of Transparent
viscosity of petroleum liquids, both transparent and opaque. and Opaque Liquids (and Calculation of Dynamic Viscos-
The kinematic viscosity, ν, in this test method is derived by ity)
dividing the dynamic viscosity, η, by the density, ρ, obtained at D2162 Practice for Basic Calibration of Master Viscometers
the same test temperature. and Viscosity Oil Standards
D6300 Practice for Determination of Precision and Bias
1.2 The result obtained from this test method is dependent
Data for Use in Test Methods for Petroleum Products and
uponthebehaviorofthesampleandisintendedforapplication
Lubricants
toliquidsforwhichprimarilytheshearstressandshearrateare
D6708 Practice for StatisticalAssessment and Improvement
proportional (Newtonian flow behavior).
of Expected Agreement Between Two Test Methods that
1.3 The range of kinematic viscosity covered by this test
Purport to Measure the Same Property of a Material
2 2
3
method is from 0.5 mm /s to 1000 mm /s in the temperature
2.2 ISO Standards:
range between –40 °C to 120 °C; however the precision has
ISO 5725 Accuracy (Trueness and Precision) of Measure-
been determined only for fuels and oils in the range of 2.06
ment Methods and Results
2 2 2
mm /sto476mm /sat40°Cand1.09 to107 mm /sat100°C
ISO/IEC 17025 General Requirements for the Competence
(as stated in Section 12 on Precision and Bias). The precision
of Testing and Calibration Laboratories
has only been determined for those materials, viscosity ranges,
3. Terminology
and temperatures as indicated in Section 12 on Precision and
Bias. The test method can be applied to a wider range of
3.1 Definitions:
materials,viscosity,andtemperature.Formaterialsnotlistedin
3.1.1 density (ρ), n—mass per unit volume.
Section 12 on Precision and Bias, the precision and bias may
3.1.2 dynamic viscosity (η), n—theratiobetweentheapplied
not be applicable.
shear stress and rate of shear of a liquid.
1.4 The values stated in SI units are to be regarded as
3.1.2.1 Discussion—It is sometimes called the coefficient of
standard. No other units of measurement are included in this
dynamic viscosity or, simply, viscosity. Thus, dynamic viscos-
standard.
ity is a measure of the resistance to flow or to deformation of
a liquid under external shear forces.
1.5 This standard does not purport to address all of the
3.1.2.2 Discussion—Thetermdynamicviscositycanalsobe
safety concerns, if any, associated with its use. It is the
used in a different context to denote a frequency-dependent
responsibility of the user of this standard to establish appro-
quantity in which shear stress and shear rate have a sinusoidal
priate safety and health practices and determine the applica-
time dependence.
bility of regulatory limitations prior to use.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
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This test method is under the jurisdiction of ASTM Committee D02 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Standards volume information, refer to the standard’s Document Summary page on
Subcommittee D02.07 on Flow Properties. the ASTM website.
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Current edition approved Dec. 15, 2014. Published March 2015. DOI: 10.1520/ Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
D7945-14. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D7945 − 14
3.1.3 kinematic viscosity (ν), n—the ratio of the dynamic 6. Apparatus
viscosity (η) to the density (ρ) of a liquid. 4,5
6.1 Constant Pressure Viscometer:
3.1.3.1 Discussion—For gravity flow under a given hydro-
6.1.1 Viscosity Measurement—The Constant Pressure vis-
static head, the pressure head of a liquid is proportional to its
cometer uses the Hagen-Poiseuille principle of capillary flow
density (ρ). Therefore the kinematic viscosity (ν) is a measure
to determine the viscosity. A length of capillary tube is
...