Capacitive liquid level meter working principle and application range

Capacitive liquid level gauges are widely used in petroleum, chemical, metallurgy, electric power, paper, pharmaceutical and other fields. The product is based on the principle of capacitive sensing, which causes a change in capacitance when the measured medium immerses the height of the measuring electrode. It can convert the change of various level and liquid level to standard current signal, and transfer it to the operation control room for secondary display or computer device for centralized display, alarm or automatic control.

Capacitance liquid level measurement principle is that the probe line and the conductive liquid form a capacitor, wherein the metal core of the probe line is a pole of the capacitor, the conductive liquid is the other pole of the capacitor, and the middle is a high stability PPR or polyvinyl fluoride. The outer layer of the insulating layer acts as a medium between the two stages. As the liquid level changes, the area of the liquid surrounding the probe line changes, causing the relative area of the two poles of the capacitor to change, resulting in a change in capacitance. The formula of the concentric cylindrical capacitor can write the relationship between the liquid height and the capacitance. The capacitance of the capacitor is affected by three factors:

1 distance between the electrode faces

2 the size of each electrode surface

3 dielectric constant of the dielectric between the electrode faces

Since Co, ε, and D/d are fixed, so: C = KH, that is, the capacitance is only proportional to the height of the liquid immersion probe (the relative area of the capacitor plates).

Capacitive level gauge application range:

Chemical plant: testing the liquid level of chemical raw materials such as polyester, spandex, acid and alkali;

Environmental protection: testing the sewage level;

Boiler factory: detecting the liquid level of the medium in the pressure vessel;

Hydraulic machinery: detecting the lubricating oil level;

Food sector: testing the level of edible oil;

Oil field: Check the product oil level.