| 摘要 |
PURPOSE:To easily check hardness of feed water for a boiler and simultaneously corrosion prevention of the boiler by coating a hardness indicator of feed water for the boiler on the surfaces of the tables of sodium phosphate used as the antiscaling agent of the small-sized one-through boiler. CONSTITUTION:Powder of sodium phosphate such as Na2HPO4.12H2O used as an anticorrosive agent of a small-sized one-through boiler is molded into the tablets having suitable size by a briquetting machine. A soln. wherein EBT (Eriochrome Black T) is dissolved in isopropylene alcohol in 1% concn. is coated on the surface of the tablets for corrosion prevention as a hardness indicator for feed water of the boiler and dried. On this occasion, the prescribed amount of a chelating agent for a hardness component is coated together with the hardness indicator and thereby the hardness components are masked and the deciding reference of hardness can be optionally preset in accordance with an allowable value for hardness in the inside of a treating system.
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