Abstract: A moisture sensor detects the presence of foreign matter in a fluid conducting conduit and produces an electrical signal which activates a pump to purge the conduit of the foreign matter. The moisture sensor includes a pair of conduits that may be formed of an electrically conductive material and a coupling for placing the pair of conduits in fluid communication. A pair of electrodes are mounted in the coupling and are insulated from one another until electrically conductive foreign matter bridges a gap between the electrodes. Bridging the gap between the electrodes causes a signal to be sent to a source of gas that injects gas in the conduits to remove the foreign material therefrom.