
Capacitance level probes consist of a long rod or cable that protrude into a vessel and its contents. The instrument sets up an electric field between the probe and the tank wall using the contents of the tank as a dielectric (a nonconductor that allows an electric field to exist within itself). If the tank is non-metal, such as plastic or brick lined, two parallel rods are mounted in the level probe or a metal strip can be run on the outside of the tank. The electric field is set-up between the two probes or the probe and the metal strip. Figure 1 shows a simplified layout for a capacitance level probe. [Read more…]