ASTM D7152-05e1
(Practice)Standard Practice for Calculating Viscosity of a Blend of Petroleum Products
Standard Practice for Calculating Viscosity of a Blend of Petroleum Products
SIGNIFICANCE AND USE
Predicting the viscosity of a blend of components is a common problem. Both the Wright Blending Method and the ASTM Blending Method, described in this practice, may be used to solve this problem.
The inverse problem, predicating the required blend fractions of components to meet a specified viscosity at a given temperature may also be solved using either the Inverse Wright Blending Method or the Inverse ASTM Blending Method.
The Wright Blending Methods are generally preferred since they have a firmer basis in theory, and are more accurate. The Wright Blending Methods require component viscosities to be known at two temperatures. The ASTM Blending Methods are mathematically simpler and may be used when viscosities are known at a single temperature.
Although this practice was developed using kinematic viscosity and volume fraction of each component, the dynamic viscosity or mass fraction, or both, may be used instead with minimal error if the densities of the components do not differ greatly. For fuel blends, it was found that viscosity blending using mass fractions gave more accurate results. For base stock blends, there was no significant difference between mass fraction and volume fraction calculations.
The calculations described in this practice have been computerized as a spreadsheet and are available as an adjunct.3
SCOPE
1.1 This practice covers the procedures for calculating the estimated kinematic viscosity of a blend of two or more petroleum products, such as lubricating oil base stocks, fuel components, residua with kerosine, crude oils, and related products, from their kinematic viscosities and blend fractions.
1.2 This practice allows for the estimation of the fraction of each of two petroleum products needed to prepare a blend meeting a specific viscosity.
1.3 This practice may not be applicable to other types of products, or to materials which exhibit strong non-Newtonian properties, such as viscosity index improvers, additive packages, and products containing particulates.
1.4 The values stated in SI units are to regarded as standard. No other units of measurement are included in this standard.
1.5 Logarithms may be either common logarithms or natural logarithms, as long as the same are used consistently. This practice uses common logarithms. If natural logarithms are used, the inverse function, exp(), must be used in place of the base 10 exponential function, 10, used herein.
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.
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Designation:D7152–05
Standard Practice for
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Calculating Viscosity of a Blend of Petroleum Products
This standard is issued under the fixed designation D7152; 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.
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´ NOTE—Adjunct reference was added editorially in October 2007.
1. Scope D7042 Test Method for Dynamic Viscosity and Density of
Liquids by Stabinger Viscometer (and the Calculation of
1.1 This practice covers the procedures for calculating the
Kinematic Viscosity)
estimated kinematic viscosity of a blend of two or more
2.2 ASTM Adjuncts:
petroleum products, such as lubricating oil base stocks, fuel
Calculating the Viscosity of a Blend of Petroleum Products
components, residua with kerosine, crude oils, and related
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Excel Worksheet
products, from their kinematic viscosities and blend fractions.
1.2 This practice allows for the estimation of the fraction of
3. Terminology
each of two petroleum products needed to prepare a blend
3.1 Definitions of Terms Specific to This Standard:
meeting a specific viscosity.
3.1.1 ASTM Blending Method, n—a blending method at
1.3 This practice may not be applicable to other types of
constant temperature, using components in volume percent.
products, or to materials which exhibit strong non-Newtonian
3.1.2 blend fraction, n—the ratio of the amount of a
properties, such as viscosity index improvers, additive pack-
componenttothetotalamountoftheblend.Blendfractionmay
ages, and products containing particulates.
be expressed as mass percent or volume percent.
1.4 The values stated in SI units are to be regarded as
3.1.3 blending method, n—an equation for calculating the
standard. No other units of measurement are included in this
viscosity of a blend of components from the known viscosities
standard.
of the components.
1.5 Logarithmsmaybeeithercommonlogarithmsornatural
3.1.4 dumbbell blend, n—ablendmadefromcomponentsof
logarithms, as long as the same are used consistently. This
widely differing viscosity.
practice uses common logarithms. If natural logarithms are
3.1.4.1 Example—a blend of S100N and Bright Stock.
used,theinversefunction,exp(3),mustbeusedinplaceofthe
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3.1.5 inverse blending method, n—an equation for calculat-
base 10 exponential function, 10 , used herein.
ing the predicted blending fractions of components to achieve
1.6 This standard does not purport to address all of the
a blend of given viscosity.
safety concerns, if any, associated with its use. It is the
3.1.6 mass blend fraction, n—The ratio of the mass of a
responsibility of the user of this standard to establish appro-
component to the total mass of the blend.
priate safety and health practices and to determine the
3.1.7 McCoull-Walther-Wright Function, n—a mathemati-
applicability of regulatory limitations prior to use.
caltransformationofviscosity,generallyequaltothelogarithm
2. Referenced Documents of the logarithm of kinematic viscosity plus a constant,
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log[log(v+0.7)]. For viscosities below 2 mm /s, additional
2.1 ASTM Standards:
terms are added to improve accuracy.
D341 Practice for Viscosity-Temperature Charts for Liquid
3.1.8 modified ASTM Blending Method, n—a blending
Petroleum Products
method at constant temperature, using components in mass
D445 Test Method for Kinematic Viscosity of Transparent
percent.
and Opaque Liquids (and Calculation of Dynamic Viscos-
3.1.9 modified Wright Blending Method, n—a blending
ity)
method at constant viscosity, using components in mass
percent.
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This practice is under the jurisdiction of ASTM Committee D02 on Petroleum
3.1.10 volume blend fraction, n—The ratio of the volume of
Products and Lubricants and is the direct responsibility of Subcommittee D02.07 on
a component to the total volume of the blend.
Flow Properties.
3.1.11 Wright Blending Method, n—a blending method at
Current edition approved May 1, 2005. Published June 2005. DOI: 10.1520/
D7152-05E01. constant viscosity, using components in volume percent.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
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Standards volume information, refer to the standard’s Document Summary page on Available from ASTM International Headquarters. Order Adjunct No.
the ASTM website. ADJD7152. Original adjunct produced in 2006.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D7152–05
3.2 Symbols: 4.3 TheASTM Blending Method calculates the viscosity of
a blend of components at a gi
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