Measuring flowing liq. pH value - detecting variation in time of signal voltages in similar measurement circuits

摘要

The measurement method for the pH value of a flowing liq. compares variations of signals in measurement circuits. Smallest variations are made ineffective. One measurement circuit has at least one measurement electrode and a reference electrode, in which a signal voltage corresponding to the pH value is generated. At least two similar measurement circuits are used. Variation in time of signal voltages in individual measurement circuits is detected. When absolute values of these changes in the circuits differ from each other during a specified time interval, the circuit with the smallest variations is made ineffective.