| 摘要 |
Simple and economical methods for accurately determining low concentrations of particulate oil in water. In one method a sample of water is first filtered at a controlled rate. A dye-impregnated pad is pressed against the upstream surface of the filter element and then removed. The upstream surface of the filter element may now be observed with the eye against colorations of known concentrations for variations in color intensity clearly discernible within the range of 0 to 30 ppm (parts per million) by volume of oil-in-water. The dye-impregnated pad is prepared by submerging a white absorbent material in a saturated solution of an oil-soluble, water-insoluble dye, and drying them in a rack under vacuum. In another method, where the sample also contains discoloring pigmented contaminants, an intermediate pad is pressed between the filter element and the dye-impregnated pad, and its coloration compared to known standards. In lieu of the intermediate pad method, a thin prefilter is placed on the upstream surface of the filter element during filtering, then discarded, and the filter element is processed as described in the first method above.
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