Safety vent valve

Abstract From the Canadian patent

A safety valve for pressure-venting sealed fluid-holding drums, or other containers to prevent, explosions, and providing for admission of ambient atmosphere to the container, to equalize internal and external pressures and thereby permit fluid to be withdrawn from the container. The valve shell comprises a capped tube, which has only a single thread formed thereon and a plurality of shelf-like abutments which extend peripherally of interior wall portions of the tube and are shaped and disposed to provide support for interior nested, valve parts, including a pair of flame-retardant screens, a pair of oppositely displaceable valving devices valve seat structure, and spring means to establish …