prSRPS EN ISO 18335:2026

Petroleum products and related products — Determination of kinematic viscosity by calculation from the measured dynamic viscosity and density – Method by constant pressure viscometer

Scope

This document specifies a procedure for determining dynamic viscosity, η, and density, ρ, for the calculation of kinematic viscosity, ν, of middle distillate fuels, fatty acid methyl ester fuels (FAME) and mixtures thereof, up to 60 % with middle distillate fuels, and lubricating oils (e.g. base oils, formulated oils), and synthetics, using a constant pressure viscometer. The range of kinematic viscosities covered in this test method is from 0,5 mm2/s to 2 000 mm2/s, with precision at 40 °C from 1,0 mm2/s to 1 286 mm2/s, and precision at 100 °C from 3,0 mm2/s to 157 mm2/s.
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). However, if the viscosity changes significantly with the shear rate, comparison with other measuring methods is only permissible at similar shear rates.