| 摘要 |
PURPOSE:To achieve the span calibration automatically and to given an alarm at the abnormal time of a DO meter, by comparing actually measured saturation value with logical saturation value of a thermometer in the waste water treatment facilities by the activated sludge method. CONSTITUTION:The value of T deg.C temperature of water adjacent to an electrode 8 is decided by an operator 10 by a signal sent from a themometer 7 while DO saturated water is blown to the electrode 8 together with air and the value of DO logical saturation at a temperature of T deg.C is found and this result is outputted to a comparator 11. At the same time, actually measured value of DO outputted from a DO indicator 9 is sent to the comparator 11 by an actually measured signal of DO outputted from the electrode 8. The value of logical saturation of DO is compared with actually measured value of DO by the comparator 11. When a deflection having prescribed value or more is found, the deflection value is regulated to the prescribed value or less by calibrating a span of the indicator 9 by a servomechanism of a span regulator 12 and an alarm device 28 is operated when the calibration of span is impossible by the remarkable deflection of data. |
