Abstract: A system for sensing the flow of an electrically conductive liquid through a nozzle. The nozzle represents one side of an electrical sensing circuit. A conductive probe is positioned near the nozzle, so that it extends into the spray. The probe represents the second side of the electrical sensing circuit. The probe is mounted on a clamp positioned on the inside of a protective enclosure. The probe is the bottom of the enclosure. When liquid sprays from the nozzle, the sensing circuit is closed. A switch responds to this by illuminating an indicator lamp. If the liquid flow ceases, the signal circuit is opened, and the switch signals this occurrence. The switch is a transistor that operates a light emitting diode.