Process Engineering Division – Instrumentation and Automation Section – Daily Question – Question from 2020-10-14

Based on the principle of capacitive induction, when the height of the medium under test immersed in the measuring electrodes changes, its capacitance changes as well. It can convert changes in the level of various substances and liquids into standard current signals, which are transmitted to the operation control room for centralized display, alarm generation, or automatic control by secondary instruments or computer systems

The liquid level is measured based on changes in capacitance (a change in the contact area leads to a change in capacitance). This method is suitable for high-temperature and viscous materials, but it can be prone to contamination, resulting in inaccurate readings. The current upgraded version is radio frequency admittance, which is said to prevent material from sticking.

Changes in the height of the electrode during measurement cause changes in its capacitance. The changes in the levels of various substances and liquids, as well as the heights of these media, are then converted into standard current signals. Suitable for high temperature, high pressure, highly corrosive environments, materials that tend to crystallize, applications requiring anti-clogging properties, resistance to freezing, as well as solid powdered and granular materials.

Based on the principle of capacitive induction, when the height of the medium under test immersed in the measuring electrodes changes, its capacitance changes as well. It can convert changes in the level of various substances and liquids into standard current signals, which are transmitted to the operation control room for centralized display, alarm generation, or automatic control by secondary instruments or computer systems

A capacitive level gauge measures the height of the liquid level by detecting changes in capacitance. It is a rod of the gold-zhi type inserted into a container filled with liquid; the metal rod serves as one pole of the capacitor, while the wall of the container acts as the other pole. The dielectric between the two electrodes is the liquid and the gas above it. Since the dielectric constant ε1 of the liquid is different from that ε2 at the liquid surface – for example, ε1 > ε2 – as the liquid level rises, the overall dielectric constant between the two electrodes of the capacitive level gauge increases, thereby increasing the capacitance. Conversely, as the liquid level drops, the ε value decreases, and the capacitance also decreases. Therefore, a capacitive level gauge can measure the liquid level by detecting changes in the capacitance between two electrodes. The sensitivity of a capacitive level gauge depends primarily on the difference between the two dielectric constants. Moreover, accurate level measurement is only possible if ε1 and ε2 remain constant. Since the medium being measured is conductive, the metal rod electrodes are covered with insulating layers. Capacitive level gauges are compact, easy to implement for remote transmission and adjustment, and suitable for measuring the level of corrosive and high-pressure media.

According to the principle of capacitive induction, changes in the height of the medium under test relative to the measuring electrodes cause changes in capacitance. Converts changes in the level of the substance or liquid into standard current signals, which are then transmitted to secondary instruments for display

Changes in the height of the electrode during measurement cause changes in its capacitance. The changes in the levels of various substances and liquids, as well as the heights of these media, are then converted into standard current signals. Suitable for high temperature, high pressure, highly corrosive environments, materials that tend to crystallize, applications requiring anti-clogging properties, resistance to freezing, as well as solid powdered and granular materials.

A capacitive level gauge measures the height of the liquid level by detecting changes in capacitance. Suitable for level measurement in media that are corrosive and high-pressure.

A capacitive level gauge is based on the principle that by changing the geometric dimensions of the capacitor or altering the properties and quantity of the medium, the capacitance can be altered. It is mainly used in applications involving static or differential pressure level measurement.

When the height of the measured medium immersed in the measuring electrode changes, it causes a change in its capacitance. It can convert changes in the level of various substances and liquids into standard current signals, which are transmitted to the operation control room for centralized display, alarm generation, or automatic control by secondary instruments or computer systems