Semi Cylindrical Non-Tactile Capacitive Sensor: Equipotential Contour and Electrical Field Analysis

The use of Non-Tactile Semi Cylindrical Capacitive Sensors is quite common in petroleum applications. While these devices are comparatively inexpensive and effective way of measurements in horizontal pipes, they lack the required accuracy in vertical pipes applications. The measurements have shown a drift of up to 35%, when 500 ml water is used as a test sample, due to spatial variation of the electric field inside the sensor. In order to analyse the situation, a two-dimensional mapping of the electric field and equipotential lines inside the sensor has been numerically calculated by employing finite difference method model using MATLAB programming environment. The electric field diversifies spatially across the cross-sectional area of the pipe and a non-homogeneous distribution has been shown by the results. This compromises the accuracy of semi cylindrical sensors in vertical pipes application.