Abstract: A pump control system for adjusting the frequency of operation of a pump motor in accordance with the demand on the pump includes means for periodically actuating the pump motor to initiate operation of the pump at periodic intervals; sensor means for sensing the condition of the operating pump motor; and means responsive to the sensor means for adjusting the periodic interval to conform the operation of the pump motor to demand on the pump.

Abstract: A horn for connection to a pressurized fluid container for sounding multiple tones has a horn body defining a sound chamber and at least one tone altering aperture extending through the horn body into the sound chamber, a sound producing mechanism located within the horn body adjacent the sound chamber, and a trigger assembly for actuating the pressurized fluid container for release of pressurized fluid to flow through the sound producing mechanism into the sound chamber to produce a sound. The horn, when the trigger mechanism is actuated, produces sound having a first tone when the tone altering aperture is unobstructed and a second tone when the aperture is obstructed.