Abstract: A breather bag for an atmospheric storage tank vent seal includes a bag made with an impermeable and flexible membrane, to be used in storage and/or transportation of liquid product in atmospheric tank, by working as a breather to air vent either in a closed type or an open type tank. Because the stored liquid product in the atmospheric storage tank is kept physically separated from atmospheric air by using the breather bag, the following advantages are obtained. Evaporative losses of liquid products stored in atmospheric tanks are averted. Thus, environmental pollution by product gases that would be expelled out of the tanks is avoided. The entry of flames due to fire in atmospheric storage tanks that contain flammable or combustible liquids is avoided, so that the chances of an accident are reduced. Hydrocontamination of stored liquid product by water present in atmospheric air in atmospheric storage tanks is also avoided.

Abstract: A method for adding or removing a liquid product to or from a tank using a breather bag attached to an upper air vent of the tank. Prior to adding a liquid product, the bag is filled with external air either by force or atmospheric pressure, and a liquid product is added to the tank between the bag and tank while simultaneously forcing the external air out of the bag by force on the bag caused by addition of a liquid product into the tank. As liquid product is removed from the tank through an outlet valve, the breather bag is sucked downward by the vacuum created between the bag and tank as the liquid product is removed. In both processes, the liquid product is separated from the external air by the breather bag, yielding the following advantages. Evaporative losses of liquid products stored in atmospheric tanks are averted. Thus, environmental pollution by product gases that would be expelled out of the tanks is avoided.