BS EN ISO 6320 pdf free download

BS EN ISO 6320 pdf free download.Animal and vegetable fats and oils – Determination of refractive index.
6? Apparatus Usual laboratory equipment and, in particular, the following. 6.1? Refractometer, for example of the Abbé type, suitable for measurements of refractive index to within ? 0,000 1 over the range n D = 1 ,300 to n D = 1 ,700. 6.2? Light source: sodium vapour lamp White light can also be used if the refractometer is fitted with an achromatic compensation system. 6.3? Glass plate, of known refractive index. 6.4? Water bath, thermostatically controlled, with a circulation pump, and capable of being maintained to the nearest ? 0,1 °C. 6.5? Water bath, capable of being maintained at the temperature at which the measurements are to be made (in the case of solid samples).7? Sampling It is important that the laboratory receive a sample which is truly representative and has not been damaged or changed during transportation or storage. Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO 5555. 8? Preparation of test sample Prepare the test sample in accordance with ISO 661 . The refractive index shall be determined on dried and filtered fats and oils. In the case of a solid sample, transfer the sample prepared in accordance with ISO 661 to a suitable container and place it in the water bath (6.5), set at the temperature at which the measurements are to be made. Allow sufficient time for the temperature of the sample to stabilize. 9? Procedure NOTE? If it is required to check whether the repeatability requirement (1 1.2) is met, carry out two single determinations in accordance with 9.1 and 9.2. 9.1? Calibration of the instrument Verify the calibration of the refractometer (6.1 ) by measuring the refractive index of the glass plate (6.3) in accordance with the manufacturer’s instructions, or by measuring the refractive index of the ethyl laurate (5.1 ).9.2? Determination Measure the refractive index of the test sample at one of the following temperatures:a)? 20 °C for fats and oils that are completely liquid at this temperature; b)? 40 °C for fats and oils that are completely melted at this temperature but not at 20 °C; c)? 50 °C for fats and oils that are completely melted at this temperature but not at 40 °C; d)? 60 °C for fats and oils that are completely melted at this temperature but not at 50 °C; e)? 80 °C or above for other fats and oils, for example completely hardened fats or waxes. Maintain the temperature of the prism of the refractometer at the required constant value by circulating through the instrument water from the water bath (6.4). Monitor the temperature of the water issuing from the refractometer using a suitable precision thermometer. Immediately before the measurement, lower the movable part of the prism to a horizontal position. Wipe the surface of the prism with a soft cloth and then with a piece of cotton wool moistened with a few drops of the solvent (5.2). Allow to dry. Carry out the measurement acccording to the operating instructions for the instrument being used. Read the refractive index to the nearest 0,000 1 as an absolute value, and record the temperature of the prism of the instrument. Immediately after the measurement, wipe the surface of the prism with a soft cloth and then with a piece of cotton wool moistened with a few drops of the solvent (5.2). Allow to dry. Measure the refractive index twice more, calculate the arithmetic mean of the three measurements and take this as the test result. BS EN ISO 6320 pdf download.