ISO 2049:1996 pdf download – Petroleum products – Determination of colour (ASTM scale)

03-01-2022 comment

ISO 2049:1996 pdf download – Petroleum products – Determination of colour (ASTM scale)
se an instrument that will illuminate and permit Observation of the Sample and any one of the colour Standards (or in the case of a three-field instrument, any two of the colour Standards) simultaneously, either by direct viewing or with an Optical eye-piece. A two-field instrument shall show two illuminated areas of equal size and shape, one filled with light transmitted by a colour Standard, the other with light transmitted by the Sample. These illuminated areas shall be disposed symmetrically about a vertical median line and shall be separated in a horizontal direction so that the horizontal Separation of the closest portions subtends the eye of the observer not less than 2” nor more than 3,6O. A three-field instrument shall show three illuminated areas in the field of view. Two areas shall be filled with light transmitted by two different colour stan- dards, and these shall be disposed symmetrically about the third area which shall be filled with light transmitted by the Sample. The rectangular dimen- sions of each of the three areas shall be the Same, and the left- and right-hand corners of the full field of view shall be rounded with a radius not exceeding half the vertical dimension. The illuminated areas shall be separated in a horizontal direction by vertical lines so that the closest Portion of the Sample area and any one of the colour Standards’ illuminated areas sub- tends the eye of the observer not less than 0,3O nor more than 0,6.
Esch illuminated area in the two-field instrument shall cover a circle of diameter subtending at least 2,2O, and may be enlarged to any size provided that no two illuminated Points in the field of view are separated by a distance subtending more than IO’. In the case of the three-field direct viewing instrument, the subtend- ing angles become 2,6O and 6,4O respectively. NOTE 2 The angle subtended by a line of length d, in a plane perpendicular to the line of sight, and separated from the eye of the observer by a distance D, is given in degrees by 57,3 d/D. The angle subtended by the image of this line, seen by viewing it through an eye-piece of magnification M, is given in degrees by 57,3 Md/Di, where Di is the distance between the eye of the observer and the plane of the image.
temperature 2750 K (or if a quartz halogen lamp is used, 3300 K), a daylight filter glass (A.2.2) and a flashed opal glass. The combined elements possess spectral characteristics similar to northern daylight. The Source shall provide a transluscent or opaque diffuse background of 900 IX + 100 IX brightness, against which the colour Standards and Sample shall be viewed. The background of illuminated opal glass shall be free from glare or shadows. The light Source shall be designed so that there is no extraneous light interfering with the Observation. NOTE 3 When electric current is not available, the color- imeter may be designed to use diffused daylight provided that direct sunlight is avoided. Coloured objects should be excluded from the immediate foreground when using diffused daylight.

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