Patent ID: 7708894

Claim:
A method of supply amount management of a water treating agent, comprising the steps of: supplying a water treating agent containing a scale inhibitor selected from chelating agents to a water-supply system of thermal equipment; collecting a water sample from the thermal equipment; quantitatively determining the scale inhibitor in the collected water sample by adding metal salt containing a specific metal ion to the sample, and adding a metal indicator or a colorimetric reagent to the sample, wherein the metal salt is added as a solution, wherein an effective amount of the metal salt is added to the sample so that the specific metal ion forms a complex with the scale inhibitor in the sample, and with the metal indicator or the colorimetric reagent added to the sample, and wherein the metal indicator is added to the sample, and a quantitative value of the scale inhibitor is determined based on the amount of the added metal salt causing the specific metal ion to start forming a complex with the metal indicator, or the colorimetric reagent is added to the sample, and the quantitative value of the scale inhibitor is determined based on a detected hue of the sample with the added metal salt and colorimetric reagent; determining a concentration of the water treating agent in the thermal equipment on the basis of the quantitative value of the scale inhibitor; and adjusting a supply amount of the water treating agent based on the determined concentration.