Importance

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Abstract

A passive vacuum relief valve for an ultra-low temperature freezer. A thermally conductive tube extends through a freezer cabinet wall and opens into the interior cabinet space. The tube also extends outwardly from the cabinet wall in thermal exposure to ambient air so that it can receive heat from the ambient air. A valve enclosure has a chamber opening into the tube and is also positioned in the ambient air. A check valve, preferably a ball type, is formed in the valve enclosure and is polarized in a direction permitting ambient air to flow through the chamber and the tube into the freezer cabinet. The exposed tube is passively heated by the ambient air and provides a thermal conduction path to the valve and to the portion of the tube extending through the freezer cabinet wall to prevent moisture from freezing and locking the valve and/or obstructing the tube.

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First Claim