Passive ventilation system and method

A method for passively venting a low density gas from a chamber having a vertical extent, comprising the steps of:

• providing an exhaust opening proximate the upper end of the chamber to allow gaseous venting from the chamber;
• providing an inlet opening proximate the upper end of the chamber and a gas impervious, heat conductive, open ended conduit from the inlet opening to a position proximate the lower end of the chamber, the conduit including a first generally horizontal portion and a second generally vertical portion;
• allowing air to enter the inlet opening;
• transferring heat through the walls of the horizontal portion of the conduit to equalize the temperatures of the interior and exteriors of the chamber to minimize the flow of air through the conduit in the absence of a low density gas inside the chamber;
• and
• allowing the air within the conduit to flow through the vertical portion of the conduit and enter the interior of the chamber at said position proximate the lower end of the chamber and the low density gas inside the chamber to exit through the exhaust opening.

A container for the storage of devices which produce a low density, hazardous gas comprising:

• a chamber having sidewalls, a bottom and a top:
• an exhaust opening proximate the top of the chamber to allow a low density gas to escape the chamber;
• an inlet opening proximate the top of the chamber to allow gas at ambient density to enter the chamber;
• a first, conduit within the chamber and extending from the inlet opening to a position proximate the bottom of the chamber so that gas at ambient density can flow into the interior of the chamber through said inlet opening to said position;
• a second generally horizontal conduit extending from the exhaust opening to a position within the chamber, a substantial portion of the second conduit contacting the first portion of the first conduit so that the first and second conduits are in heat exchange relationship with each other;
• and
• wherein said first conduit comprises a first portion proximate the top of the chamber to allow heat transfer between the interiors of the first and second conduits through the walls of the conduits to equalize the temperature of the gas in the first conduit and the temperature of the gas inside the second conduit to minimize flow through the first conduit in the absence of a low density gas inside the chamber, and a second portion extending from the first portion to said position proximate the bottom of the chamber.

A container for the storage of batteries, comprising:

• a chamber having sidewalls, a bottom and a top;
• an exhaust opening in one of said sidewalls proximate the top of the chamber to allow the low density gas to escape the chamber;
• an inlet opening having an area larger than the area of the exhaust opening in one of said sidewalls proximate the top of the chamber to allow air at ambient density to enter the chamber;
• and
• a heat conductive, open ended, gas impervious tube within the chamber and extending from the inlet opening to a position proximate the bottom of the chamber so that gas at ambient density can flow into the interior of the chamber through said inlet opening to said position, said tube including a first substantially horizontal portion proximate the top of the chamber to allow heat transfer between the interior and the exterior of the tube through the walls of the conduit to equalize the temperature of the gas in the tube and the temperature of the gas inside the chamber to minimize flow through the tube in the absence of a low density gas inside the chamber, and a second substantially vertical portion extending from the first portion to said position proximate the bottom of the chamber.