ISO 23581:2024

This document specifies a procedure for the determination of kinematic viscosity, ν, by calculation from dynamic viscosity, η, and density, ρ, of both transparent and opaque liquid petroleum products and crude oils using the Stabinger type viscometer. The result obtained using the procedure described in this document depends on the rheological behaviour of the sample. This document is predominantly applicable to liquids whose shear stress and shear rate are proportional (Newtonian flow behaviour). If the viscosity changes significantly with the shear rate, comparison with other measuring methods is not possible except at similar shear rates. The precision has been determined only for the materials, density ranges and temperatures described in Clause 13. The test method can be applied to a wider range of viscosity, density, temperature and materials. It is possible that the precision and bias are applicable for materials which are not listed in Clause 13.