ISO 21493:2019 pdf download

ISO 21493:2019 pdf download

ISO 21493:2019 pdf download.Petroleum products – Determination of turbidity point and aniline point equivalent
1 Scope
This document specifies a method to determine the turbidity point of petroleum products based on distillates from crude oil.
This document also specifies how to convert the turbidity point to an aniline point equivalent.
This document describes a procedure using automated or automatic apparatus suitable for transparent samples with an initial boiling point above ambient temperature.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 648, Laboratory glassware – Single-volume pipettes
ISO 3170, Petroleum liquids – Manual sampling
ISO 3171, Petroleum liquids – Automatic pipeline sampling
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
– ISO Online browsing platform: available at
– IEC Electropedia: available at
Reduce the viscosity of viscous or waxy samples by warming to a temperature below that which would cause the loss of light ends or the dehydration of the drying agent. If suspended water is visibly present, centrifuge the sample to remove the water before carrying out the final drying with drying agent. Remove any suspended drying agent by centrifuge or filtration. Heat samples containing separated wax until they are homogenous and keep heated during the centrifuging or filtration operations.
9 Procedure
9.1 Clean and dry the apparatus.
9.2 Pipette 10 ml± 0,02 ml of p-anisaldehyde and 10 ml± 0,02 ml of the sample into the test tube.
lf the material is too viscous for pipetting, weigh to the nearest 0,01 g, a quantity of the sample corresponding to 10 ml at room temperature.
9.3 Prepare the apparatus in accordance with the manufacturer ’ s instructions.
Use the expected temperature for the sample as guidance for setting up the apparatus. If the sample is unknown, perform an exploratory scan on the sample to determine the approximate turbidity point,and use that temperature for the immediate repeat analysis of the same material.
‘9.4 Stir the p-anisaldehyde-sample mixture the inclusion of air bubbles and, if necessary, heating at a rate of to until complete obtained by applying heat directly to the jacket tube.
lf the p-anisaldehyde-sample mixture is completely miscible at room temperature, substitute a non-aqueous cooling bath for the heat source.