Length Effects on Capacitance Measurements of a Cylindrical Cell Probe

Using two different capacitive cell probes; and monitoring capacitance and resistance values of the air and water liquids, the cell length and conductance effects of the water liquids are studied. Variations of the dielectric air capacitance and reactance capacitance parameter of liquids with cylinder length are investigated. In another study the probe length affects on the capacitance and resistance measurements for the liquid filling process are investigated. Different theories are also developed to calculate the capacitance values for the constructed probes. Capacitance per unit length from the Coulomb theory is different from the Gauss law that is a constant value. Measured air capacitance of 24.7 pF (15.3 pF) and calculated ones Gauss, 19.39 pF (9.66 pF), and Coulomb 24.7 pF (15.3 pF) for the long (short) probe are obtained. A comparison of the experimental air capacitance results with the Coulomb theory shows a relative error percentage of 10.58% for the long probe and an error of 27.32% for the short probe. For liquid samples, there is a good agreement between the measured conductivity results by the EC and the two cylindrical cell probes using LRC module. In particular for the distilled, mineral, tap and boiled water samples the relative errors for the short and long cylindrical probes are lower than 2%, which is a good agreement for such measurements. Obtained results verifies that the reported cylindrical sensor could be effectively implemented for the study of low conducting liquids such as regular water and dilute water solutions