ISO 2049 Petroleum products - Determination of colour (ASTM scale)
7 Procedure
7.1 Fill two sample containers (5.2) if using a two-field comparator, or three sample containers if using a three-field comparator, with water (4.1) to a depth of at least 50 mm, and place one container in the sample compartment and the other(s) in the standard glasses compartment of the colorimeter. Switch on the artificial daylight source and confirm that the light intensity through all compartments is equal when the standard glasses are not in the path of the daylight source.
7.2 Place a sample container (5.2) or containers, filled to a depth of at least 50 mm with water (4.1) in that compartment or compartments of the colorimeter through which the standard glasses will be observed. Place the Sample in its container in the other compartment. Cover the containers with the sample cover (5.3) to exclude all exterior light.
7.3 Switch on the light source of the colorimeter and compare the colour of the sample with that of the standard glasses. If using a three-field comparator, bracket the sample by darker and lighter glass discs or by an exact match and a darker glass disc. Determine, for two-field comparators, which glass matches the colour of the Sample; or if an exact match is not possible, then use that glass which has the next darker colour.
