D156_10 (15)

Flush the oil tube with a portion of the test specimen, taking care to allow the tube to drain thoroughly. Fill the oil tube with the test specimen. Compare with a whole color standard. Fill the oil tube with the test specimen. Compare with a whole color standard. When the test specimen is lighter than the color standard, remove the standard and replace it with a half standard. When the sample is darker than the single hole standard, at 6 and 1/4 inch or 150 millimeters add another hole standard. Warning. It is important that all samples in the color tubes be free from air bubbles. With the proper color standard or standards in place and the test specimen in the oil tube at a level where it's color is decidedly darker than that of the color standard, draw off the test specimen slowly by means of the petcock until the oil appears just slightly darker than the color standard. From this point, draw the test specimen level down to the nearest depth corresponding to color number, as shown in Table 1 of the written standard. When the color of the oil observed through the eyepiece is still darker than the color standard, draw the oil down to the next depth given in Table 1 of the written standard and compare. Continue this operation until a depth is reached where the test specimen and color standard match or show questionable differences. At this point, lower the oil column to the next specified depth, and when the oil is unmistakably lighter than the color standard, record the color corresponding to the next higher level as a Siebel color. Experience in the use of this instrument will obviate the necessity of following this step by step procedure outlined in section 10.2 of the written standard for choosing the proper color standards for each sample. Examples of the procedure are given in Table 2 of the written standard.