ISO 21493 specifies a method to determine the turbidity point of petroleum products based on distillates from crude oil.
ISO 21493 also specifies how to convert the turbidity point to an aniline point equivalent.
ISO 21493 describes a procedure using automated or automatic apparatus suitable for transparent samples with an initial boiling point above ambient temperature.
Note: ISO 21493 is intended to be a complement, not a replacement, to ISO 2977 for the determination of aniline point and mixed aniline point.
The same apparatus is used for ISO 2977, wherein method 5 is used to determine the turbidity point. It is also possible to convert the turbidity point to the aniline point equivalent and vice versa. The aniline point equivalent is useful when comparing results from using the method described ISO 21493 to the aniline point according to ISO 2977 method 5.
ISO 21493 on the determination of turbidity point and aniline point equivalent is useful for:
The turbidity point and the aniline point equivalent are useful as an aid in the analysis of hydrocarbon mixtures. Aromatic hydrocarbons exhibit the lowest values and paraffins the highest, with cycloparaffins and olefins exhibiting intermediate values. In a homologous series, the turbidity point and the aniline point equivalent increase with increasing molecular mass.
Although the turbidity point and the aniline point equivalent can be used in combination with other physical properties in correlative methods for hydrocarbon analysis, the most frequent usage is to provide an estimate of the aromatic content (or "aromaticity") of hydrocarbon mixtures.
ISO 21493 guides you on determining turbidity and aniline point with accuracy, precision and allows you to convert turbidity point to aniline point equivalent.
ISO 21493