Continuous liquid level measurement using a linear electrode array

This paper describes a novel continuous liquid level measurement technique based on a linear electrode array, which is vertically immersed in the liquid to inject an electric current into it and measure the voltage profile at different depths. We develop models that describe the relationship between voltage and liquid level for several vessel geometries of practical interest. Then, an inverse problem iterative algorithm is used to calculate the liquid level from the set of voltage measurements. The level accuracy values are far smaller than the interelectrode spacing and no calibration procedure is required. We describe a prototype measurement system to measure the water level in a 100 cm deep rectangular tank with a level accuracy of 3 mm when the electrodes are 5 cm apart.