Liq. level control device for pipe systems - generates signal to shut corresponding valves or pumps in case of leakage

摘要

In the case of a fault, i.e. a contact between detector and an unwanted liquid, conductance or capacitance between two electrodes is changed, so that acoustic, electric or optical signals are generated. They are received by a respective receiver and shut or disconnect the valves or pumps through corresponding control circuits. The detector electrode lies at the input of an MOS inverter which is connected through a resistor to the supply voltage. The capacitor component of an RC circuit is dependent on the moisture content and this affects the resonance characteristics of a piezo-electric oscillator.