Principle is the variation of the measured capacitance thermometer to measure the liquid surface height

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in the production of thermometer is mainly used for liquid level such as pot, kettle, tower or interface detection and control. Should first understand the working principle of the thermometer in the operation.

thermometer principle is used to measure the change of capacitance level to measure the liquid surface. It is a metal rod inserted into the liquid container, metal bar as a capacitor, the container wall as the capacitance of the other. The medium between the two electrodes is above the liquid and gas. As a result of the liquid permittivity & epsilon; 1 and on the surface of the liquid permittivity & epsilon; 2 different, such as: & epsilon; 1 > ε 2, when the liquid level increases, the overall dielectric constant value between the two electrodes mounted electric capacity increase consequently. Conversely when the liquid level drops, & epsilon; Value decreases, and also reduce the capacitance. So, through the change of capacitance between the two electrodes to measure the liquid level height. Capacitance the sensitivity of the thermometer mainly depends on the difference between two kinds of dielectric constant, and only & epsilon; 1 and & epsilon; 2 constant can guarantee the accuracy of the level measurement, due to the electrical conductivity measured medium, so a metal electrode insulation cover. Capacitance thermometer is small in size, easy to implement remote transmission and adjust, suitable for the corrosive and high pressure in the medium level measurement.

when the lowest level, blow out air bubbles without resistance, zero back pressure, pressure gauge refers to zero; When liquid level increased, bubble blown out to overcome the static pressure of liquid column, back pressure increases, the pressure indicator. Back pressure, therefore, the pressure gauge indicates the pressure size, height is reflected in the liquid surface. Bubble thermometer has simple structure, low price, suitable for measuring the corrosive, viscosity and exposure level of container containing suspended particles, but the precision is low.