Patent ID: 7556178

Claim:
In combination, an enclosed, liquid containing reservoir and a vacuum relief mechanism comprising a vacuum relief device and a one-way valve; the reservoir having a reservoir outlet from which liquid is to be dispensed and within which reservoir a vacuum below atmospheric pressure is developed on dispensing liquid from the reservoir outlet, the vacuum relief device is adapted to permit atmospheric air to enter the reservoir to reduce any vacuum developed in the reservoir, the vacuum relief device comprising an enclosed chamber having an air inlet and a liquid inlet, the liquid inlet open to the chamber at a height which is below a height at which the air inlet is open to the chamber, the air inlet in communication with atmospheric air at atmospheric pressure such that the chamber is at atmospheric pressure, the liquid inlet connected by via a liquid passageway with liquid in the reservoir, the liquid inlet at a height below a height of liquid in the reservoir such that when pressure in the reservoir is atmospheric pressure, due to gravity the liquid from the reservoir fills the liquid passageway and, via the liquid passageway, fills the chamber to a height above the height of the liquid inlet and below the height of the air inlet, and wherein on dispensing liquid from the reservoir outlet increasing vacuum below atmospheric in the reservoir, the height of liquid in the chamber decreases until the height of liquid is below the height of the liquid inlet and the liquid inlet is open to air in the chamber such that air in the chamber attempts to flow under gravity upward through the liquid passageway to the reservoir to decrease vacuum in the reservoir, the one-way valve disposed across the liquid passageway between the liquid inlet and the reservoir movable between a closed position preventing flow between the reservoir and the liquid inlet and an open position permitting flow between the reservoir and the liquid inlet.