ISO 21493:2019 Petroleum products一Determination of turbidity point and aniline point equivalent

ISO 21493:2019 Petroleum products一Determination of turbidity point and aniline point equivalent. 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 https://www.iso.org/ohp — IEC Electropedia: available at http://www.electropedia.org/ 3.1 turbidity point minimum equilibrium solution temperature, in degrees Celsius, of a mixture of equal volumes of p-anisaldehyde and the product under test 3.2 aniline point equivalent Aeq calculated temperature based on the turbidity point (3.1) 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 (5.1) and 10 ml ± 0,02 ml of the sample into the test tube. If the material is too viscous for pipetting, weigh to the nearest 0,01 g, a quantity of the sample corresponding to 10 ml ± 0,02 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,...