Standard Practice for Calculating Viscosity of a Blend of Petroleum Products

Importancia y uso:

5.1 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.

5.2 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.

5.3 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.

5.4 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.

5.5 The calculations described in this practice have been computerized as a spreadsheet and are available as an adjunct.3

Subcomité:

D02.07

Volúmen:

05.03

Número ICS:

75.080 (Petroleum products in general)

Palabras clave:

blending; kinematic viscosity; MacCoull; viscosity; Wright;