The capacitance level gauge is a device that converts the change in the position of the measured object into capacitance. It has the advantages of simple structure, high resolution, reliable operation and fast dynamic response. In addition, it provides non-contact measurements, and can work under harsh conditions such as high temperature, radiation and strong vibration. It has been used in various fields of industrial and agricultural production.
The capacitance level gauge uses to measure the change of capacitance to measure the height of the liquid level. There is a metal rod inserted into the liquid container, which serves as one pole of the capacitor, and the container wall serves as the other pole of the capacitor. The medium between the two electrodes is the liquid and the gas above it.
The dielectric constant ε1 of the liquid is different from the dielectric constant ε2 on the liquid surface, such as ε1>ε2. When the liquid level rises, the total dielectric constant value between the two electrodes of the capacitance level gauge will increase accordingly, and the capacitance will also increase. On the contrary, when the liquid level drops, the ε value decreases, and the capacitance will also decrease.
Therefore, the capacitance level gauge can measure the level of the liquid through the change of the capacitance between the two electrodes.
The sensitivity of the capacitance level gauge mainly depends on the difference between the two dielectric constants. Moreover, only when ε1 and ε2 are constant can ensure the accuracy of liquid level measurement. Since the measured medium is conductive, the metal rod electrodes are covered with an insulating layer. The capacitance level gauge is small in size and easy to achieve remote transmission and adjustment. So, it is suitable for level measurement of corrosive and high-pressure media.