A brief overview of the measurement principle of external-mounted level gauges

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The external-mounted level gauge operates on the principle of capacitive sensing: as the height of the medium being measured changes and it comes into contact with the measuring electrodes, this causes a change in 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. 　　This instrument effectively eliminates the influence of factors such as temperature, humidity, pressure, and the electrical conductivity of materials on the measurement process, thereby offering high resistance to interference and reliability. It can measure highly corrosive liquids such as acids, bases, salts, and sewage. Capable of measuring high-temperature, high-pressure media ； Process temperature: -40~600℃ ； Process pressure: -0.1 to 4.0 MPa. It features a unique two-point on-site calibration technique, which facilitates easy use of the product by users. 　　A surface-mounted level gauge measures the height of the liquid level by detecting changes in capacitance. It consists of a metal rod inserted into the container holding the liquid, with the metal rod serving as one pole of the capacitor and the container wall serving as the other pole. The dielectric between the two electrodes is the liquid and the gas above it. This is because the dielectric constant ε1 of the liquid is different from the dielectric constant ε2 at the liquid surface. 　　For example, if ε1 > ε2, then as the liquid level rises, the overall dielectric constant between the two electrodes increases, thereby increasing the capacitance. Conversely, as the liquid level drops, the ε value decreases, and the capacitance also decreases. Therefore, the level of the liquid can be measured by the change in capacitance between the two electrodes, and its sensitivity depends primarily on the difference between the two dielectric constants. 　　Moreover, only the constancy of ε1 and ε2 can ensure accurate level measurement; since the medium being measured is conductive, the metal rod electrodes are all covered with insulating layers. Capacitive level gauges are compact, easy to enable remote transmission and adjustment, and suitable for measuring the level of corrosive and high-pressure media. 　　Its probe and transmitter are separated into two parts, and the length of the shielded cable connecting them can reach 1 kilometer; it can be installed in harsh environments and is particularly suitable for applications involving high temperatures, vibration, corrosion, hazardous conditions, or situations where remote setting is required. It transmits level changes to an on-site indicator to show the actual level height, and is equipped with a level alarm and a level remote transmission device. 　　I hope the above information will help everyone understand this instrument better.