If you’re looking for a level sensor versatile enough to measure liquids, powders or other granular solids, slurries, and more, a capacitive level sensor might be just what you’re looking for.

Capacitive level sensors are operated by two electrodes forming a capacitor, often in the form of two parallel metal plates with insulating (non-conductive or “dielectric”) material separating them. In the most basic sense, capacitors store electrostatic energy in an electric field. The capacitor’s ability to store this energy (a measurement known as “capacitance”) increases as voltage is applied to the circuit, and as the volume of insulating material increases.

Airplane Tachometer

Airplanes often use capacitive sensors to gauge fuel and other engine needs due to their accuracy in spite of turbulence and agitation.

When functioning as level sensors, capacitors work by processing capacitance with reference to the dielectric constant of the material being measured and the voltage being used to complete the circuit. These measurements are used to determine vessel levels. Higher levels of dielectric material result in greater capacitance, meaning the former can be easily gauged with the latter.

This method of level measurement is sometimes called RF level sensing, after the radio frequencies applied to the capacitor circuit.

As an example, let’s say that we’re measuring a high-capacitance solution stored within a large metal tank. The two electrodes that form the capacitor will be in the form of a conductive probe like a metal plate, and the vessel wall itself. An RF signal is activated, causing a low current to flow through the solution. This current varies depending on the amount of solution in the tank – a difference which is detected by the capacitor switch and translated into an output suitable for the specific application.

In addition to the wide range of materials and applications capacitive level sensors are capable of performing with, they also have the advantage of being mechanically simple with no moving parts and minimal required maintenance. In addition, they’re well-suited for both point and continuous level measurements and are resistant to agitation.

To learn more about level sensors for your specialized industrial application, contact the experts at SMD Fluid Controls. They’ll work with you to come up with the best level sensor for your specific needs, whether it’s capacitive, ultrasonic, a simple float switch, or anything else.


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