The Capacitive Level Transmitter measures the changing capacitance between the sensing probe and the reference ground to determine the level of material in the tank.
When the sensing probe is in the air only (no material around the sensing probe, the container is empty), the amount of capacitance is measured.
As the target material begins to increase and surrounds the sensing probe, the capacity varies proportionally until the maximum level of material is reached.
The difference in capacitance between the value with the material present at a given point of the probe and the value in the air only is proportional to the level of target material on the detection probe.