Sensor for sensing the presence of electrolyte solution

Abstract

A liquid sensor for detecting, in a non-contact manner, whether an electrolyte solution is flowing through a pipeline. A pair of electrodes, on which an AC voltage is impressed, are mounted on the outer surface of a pipeline formed of a material having a high dielectric constant, such as a ceramic, and a discrimination between the presence and the absence of the electrolyte solution in the pipeline is made based on variations in capacitance between the electrodes. In the presence of the electrolyte solution flowing through the pipeline, the capacitance between the electrodes is high because of the conductivity of the electrolyte solution. In the absence of the electrolyte solution flowing through the pipeline, the capacitance is determined by air and is, therefore, low. Since the electrodes are maintained in a non-contact relation with the electrolyte solution, degradation of characteristics due to corrosion is obviated. The absence of intermediates which, if present, would cause a lowering in detection sensitivity ensures an extremely high accuracy of detection.