(ISO 5661 International Standard INTERNATIONALORGANIZATION FOR STANDARDIZATIONMEKAYHAPOAHAA OPTAHM3ALMA NO CTAHAAPTW3AUWMORGANISATION INTERNATIONALEDE NORMALISATION Petroleum products - Hydrocarbon liquids - Determination of refractive index Produits petroliers - Hydrocarbures liquides -- Détermination de I'indice de refraction First edition - 1983-10-15 UDC 665.7 : 535.324 Ref. No. ISO 5661-1983 (E) ISO 5661-1983 (E) Descriptors : petroleum products, hydrocarbons, liquid fuels, tests, determination, refractive index, optical tests, reference materials. Price based on 2 pages Not for Resale Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of developing International Standards is carried out through ISo technical committees. Every member body interested in a subject for which a technical committee has been authorized has the and non-governmental, in liaison with IsO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISO Council. International Standard ISO 5661 was developed by Technical Committee iSO/TC 28, Petroleum products and lubricants, and was circulated to the member bodies in December 1981. It has been approved by the member bodies of the following countries : Austria India South Africa, Rep. of Belgium Iraq Spain Brazil Israel Sri Lanka Canada Japan Sweden Czechoslovakia Korea, Rep of Switzerland Egypt, Arab Rep. of Netherlands Turkey France Peru United Kingdom Germany, F.R. Poland USA Hungary Romania USSR The member bodies of the following countries expressed disapproval of the document on technical grounds: Australia Ireland International Organization for Standardization, 1983 ? Printed in Switzerland Copyright International Organization for Standardization Not for Resale nse fromIHS ISO 5661-1983 (E) INTERNATIONAL STANDARD Petroleum products - Hydrocarbon liquids Determination of refractive index Scope and field of application NOTES Refractive index may also be defined as the sine of the angle of in- cidence divided by the sine of the angle of refraction, as light passes 1.1 This International Standard specifies a method for the from air into the substance. This is the relative index of refraction. If determination of the refractive index of transparent and light- the absolute refractive index (i.e., referred to a vacuum) is desired, this coloured hydrocarbon liquids such as are used in capacitors, value should be multiplied by the factor 1,000 27, the absolute refrac- transformers, circuit breakers and in cables of the oil-filled type. tive index of air. 2 The numerical value of the refractive index of liquids is an inverse 1.2 This method is applicable to liquids having refractive in- function of both the wavelength of the light and temperature. For dices in the range 1,33 to 1,7 and at temperatures of 20 to mineral oils, a test temperature of 20 oC and a wavelength of 30 oc. It is not applicable, within the accuracy stated to liquids 589,3 nm, equivalent to the mean wavelength of the doublet in the having colours darker than 4 colour to IS0 2049, or to liquids sodium spectrum, are commonly used. having bubble points so close to the test temperature that a reading cannot be obtained before substantial deterioration 4 Materials takes place. NOTES Solvent 4.1 1. Liquid certified reference materials are available for the range 1,33 to 1,50, but not above this range. The accuracy of the method is not Any suitable clean volatile solvent may be used. Acetone or readily checked in the range 1,5 to 1,7. aliphatic hydrocarbon solvents boiling below 80 °c have been 2 Although measurements may be made at temperatures up to found to be satisfactory. 70 C, the accuracy of the method under these conditions has not been evaluated. Apparatus 5 The refractive index of a liquid