DETECTION OF END POINT OF ION EXCHANGE TYPE PURE WATER-PRODUCING APPARATUS

摘要

PURPOSE: To provide a method for effectively detecting the end point of an ion exchange device when the above apparatus is used for such applications where water flow and the stop of the water flow are repeated in a short period of time. CONSTITUTION: There is the period of time when the purity of pure water decreases regardless of the presence or absence of the degradation in the performance of ion exchange resins for about 15 to 30 seconds from the start of the first water flow after the stop of the long-time water flow. The time is kept measured from the moment of the first water flow after the stop of the water flow over the long time (T1) no matter the water flow for the short time thereafter is on or off. The period (T2) during this time measurement is set as an alarm mask period and an end point alarm is not outputted in this period (T2). An alarm monitor period (T3) is started when the measurement time exceeds the second prescribed period. The alarm is emitted by judging the end point of the ion exchange resins when the measured value of the electric conductivity of the water flow during the alarm monitor period (T3) exceeds the predetermined reference value of the electric conductivity. The end point of the ion exchange resins is stably and effectively detected.