Abstract: A tank ventilation exhaust fan having the unique ability to provided positive exhaust on a continuous basis while diluting the contaminated air and vapors, being emitted by the tank, with fresh air at a ratio in excess of five to one. A mixing chamber within the fan housing allows the fan to mix fresh air with vapors from the tank and expel the mixture over several hours. An alternate embodiment allows for continuous dilution of the tank's vapors.

Abstract: The disclosed invention describes a vehicle waste tank ventilation exhaust fan, having the unique ability to provided positive exhaust on a continuous basis while diluting the contaminated air and odor being emitted by the waste tank with fresh air at a ratio in excess of five to one. A vacuum is drawn on the tank when the flush valve is closed by a small fan located over the tank vent pipe. A mixing chamber within the fan housing allows the fan to mix fresh air with odor from the tank and expel the odorous mixture over several hours.