Patent ID: 7553424

Claim:
A method for controlling a sterile water production device operable to cause at least injection of an aqueous hypochlorite solution into a raw water to thereby produce a sterile water of weak acidity which contains a hypochlorous acid as an active ingredient, said method being characterized by the steps of: detecting decrease of pH of said sterile water to a level smaller than a preset pH, and responsive thereto, increasing injection rate of said aqueous hypochlorite solution so as to inject an additional aqueous hypochlorite solution into said sterile water, so that the thus-decreased pH of the sterile water is increased back to said preset pH; then, determining a molar quantity of residual alkaline impurities present in the thus-injected additional aqueous hypochlorite solution; calculating and obtaining an additional amount of said aqueous hypochlorite solution for injection of a predetermined amount of further additional aqueous hypochlorite solution, wherein said predetermined amount of further additional aqueous hypochlorite solution is an amount required to yield additional content of hypochlorous acid in a resulting sterile water to be produced, to such a degree that a molar quantity of said particular hypochlorous acid is equal to the thus-determined molar quantity of residual alkaline impurities; then, increasing injection rate of said aqueous hypochlorite solution so as to inject said predetermined amount of further additional aqueous hypochlorite solution into the sterile water produced thus far, thereby yielding sterile water of increased pH in which said molar quantity of said hypochlorous acid is equal to said determined molar quantity of residual alkaline impurities; and injecting an acid aqueous solution so as to decrease said increased pH back to said preset pH.