Design, Development and Testing of a Semi Cylindrical Capacitive Array Type Liquid Interface Level Sensor

Abstract

In this study, a semi cylindrical capacitive array type liquid interface level measuring sensor is described. The sensor consists of a continuous large semi cylindrical thin metallic plate acting as a common plate of the capacitor and an array of small semi cylindrical thin metallic plates, separated by very small gap distance. All plates are mounted along the outer wall of a cylindrical non conducting vertical storage tank. The detection of liquid interface is based on the measurement of capacitance of the array of plates which varies with the dielectric constant of the liquid within the tank. The measured capacitance has been obtained in nano farad range. Since the sensor is non contact type, it can be used for both conducting and non conducting type of liquid contained within a non conducting tank. Experimental results confirm the satisfactory performance of the sensor for liquid interface level measurement.

A simple impedance tester for determining the water content in organic solvents

“…A similar detection cell arrangement with semi-tubular electrodes was used, e.g., for determining the water content in crude oil [23], soil water content [24] or the water level of a liquid in a tank [25]. In these works a change in the capacitance of the detection cell was converted to a change in the phase angle [23] or to a voltage [24,25].…”

“…In these works a change in the capacitance of the detection cell was converted to a change in the phase angle [23] or to a voltage [24,25]. In all these cases, the analytical signal was obtained from the changes of the alternating current passing through the detection cell from an external source.…”

Contactless liquid-level measurement through opaque container using millimeter-wave sensor

“…General capacitive liquid-level sensors measure the electrical capacitance between two electrodes immersed in a liquid and calculate the liquid level from the capacitance [1]. A capacitive semi-cylindrical sensor mounted around a liquid container can measure liquid level without contacting the liquid [2], but its measurement accuracy is not high because the capacitance is strongly dependent on the distance between a container and a sensor. Consequently, optical sensors [3,4] are not suitable for measuring the level of liquid in opaque containers or containers with labels.…”

“…There is a large variety of methods for liquid-level measurement, ranging from electrical sensors, mechanical floats, and fiber optics to ultrasonic methods [1][2][3][4][5][6]. Most of these methods, however, are not suitable for measuring liquid level through an opaque container without contacting the liquid.…”

Build-up detection and level monitoring by using capacitive glocal technique

“…Float type mechanical device is the most common approach used to detect the level by switching between the upper and lower limits. Pressure sensing technique works on the basis of detecting change of pressure increasing or decreasing the liquid level from a container [4][5].…”