| 摘要 |
PROBLEM TO BE SOLVED: To rapidly determine an epoxy additive at the field without requiring any experience by using the mixed liquid of thiosulfate and a pH indicator for determining the epoxy additive. SOLUTION: A fixed amount of sodium thiosulfate solution and a water-soluble solvent are mixed in advanced and a small amount of pH indicator is added, which is mixed with refrigerating machine oil containing epoxy. The epoxy reacts with the sodium thiosulfate to generate sodium hydroxide, and the mixed liquid becomes alkali. Therefore, coloration is made by the operation of the pH indicator. When the concentration of the sodium thiosulfate solution is set to approximately 0.07-4.5 M, a coloration reaction easily advances, thus rapidly determining epoxy. Also, sufficient coloration can be obtained by approximately 0.002 pts.wt pH indicator, The concentration of epoxy in the refrigerating machine oil can be easily determined by the intensity of the coloring.
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