Abstract:
A system to sense changes in the state of an ion exchange resin bed which includes first and second current electrodes spaced from each other, a first electrical circuit electrically connecting the current electrodes and designed to be connected to a source of alternating current, and also including first and second voltage probes spaced from each other and located approximately between said first and second current electrodes with a wire connecting voltage probes. A second electrical circuit consists of the first and second voltage probes, the wire and the portion of the resin bed lying between said voltage probes so that when the first electrical circuit is energized by the source of alternating current a voltage is induced in the second electrical circuit which corresponds to the state of the resin bed located between the first and second voltage probes.