ASTM D7042 Test Method for Dynamic Viscosity and Density of Liquids by Stabinger Viscometer (and the Calculation of Kinematic Viscosity)
1. Scope
1.1 This test method covers and specifies a procedure for the concurrent measurement of both the dynamic viscosity, η, and the density, ρ, of liquid petroleum products and crude oils, both transparent and opaque. The kinematic viscosity, ν, can be obtained by dividing the dynamic viscosity, η, by the density, ρ, obtained at the same test temperature.
1.2 The result obtained from this test method is dependent upon the behavior of the sample and is intended for application to liquids for which primarily the shear stress and shear rate are proportional (Newtonian flow behavior).
1.3 The precision has only been determined for those materials, viscosity ranges, density ranges, and temperatures as indicated in Section 15 on Precision and Bias. The test method can be applied to a wider range of materials, viscosity, density, and temperature. For materials not listed in Section 15 on Precision and Bias, the precision and bias may not be applicable.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D396 Specification for Fuel Oils
D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
D975 Specification for Diesel Fuel Oils
D2162 Practice for Basic Calibration of Master Viscometers and Viscosity Oil Standards
D2270 Practice for Calculating Viscosity Index from Kinematic Viscosity at 40 °C and 100 °C
D4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
D6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
D6617 Practice for Laboratory Bias Detection Using Single Test Result from Standard Material
D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
D6751 Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
D7467 Specification for Diesel Fuel Oil, Biodiesel Blend (B6 to B20)
2.2 ISO Standards:
ISO 5725 Accuracy (Trueness and Precision) of Measurement Methods and Results
ISO 8217 Specifications for Marine Fuels
ISO/IEC 17025 General Requirements for the Competence of Testing and Calibration Laboratories
2.3 Other Documents:
NIST Technical Note 1297 Guideline for Evaluating and Expressing the Uncertainty of NIST Measurement Results
3. Terminology
3.1 Definitions:
3.1.1 density (ρ), n - mass per unit volume.
3.1.2 dynamic viscosity (η), n - the ratio between the applied shear stress and rate of shear of a liquid.
3.1.2.1 Discussion - It is sometimes called the coefficient of dynamic viscosity or, simply, viscosity. Thus, dynamic viscosity is a measure of the resistance to flow or to deformation of a liquid under external shear forces.
3.1.2.2 Discussion - The term dynamic viscosity can also be used in a different context to denote a frequency-dependent quantity in which shear stress and shear rate have a sinusoidal time dependence.
3.1.3 kinematic viscosity (ν), n - the ratio of the dynamic viscosity (η) to the density (ρ) of a liquid.
3.1.3.1 Discussion - For gravity flow under a given hydrostatic head, the pressure head of a liquid is proportional to its density (ρ). Therefore the kinematic viscosity (ν) is a measure of the resistance to flow of a liquid under gravity.
3.1.4 relative density (also called specific gravity (SG)), n - the ratio of the density of a material at a stated temperature to the density of a reference material (usually water) at a stated temperature.
