5 Procedure
5.1 Determine the density at 15 °C of the sample, to the nearest 0.1 kg/m3, by the procedure described in ISO 3675 or ISO 12185, using the corrections given in ISO 91 if appropriate.
5.2 Determine the temperatures, to the nearest 1 °C, at which 10 % (V/V), 50 % (V/V) and 90 % (V/V) of the sample is recovered during distillation, corrected to standard barometric pressure, by the procedure described in ISO 3405.
5.3 Test method ISO 3924 may be used as an alternative to test method ISO 3405 to determine the 10 %, 50 % and 90 % recovery temperatures of the fuel.
5.4 If test method ISO 3924 is used, convert the ISO 3924 data to estimated ISO 3405 data, following instructions of the former document on the calculation of equivalent data, and use the estimated ISO 3405 data in place of actual ISO 3405 data in the calculations.
6 Calculation
6.1 Calculate the cetane index using the following procedure:
Insert the measured values (see 5.1 and 5.2) in Formula (1) below and calculate the cetane index, CI:
6.2 The cetane index may also be derived by using nomography (see Annex A). However, in case of dispute, the procedure as given in 6.1 is to be applied.