IMPROVED VAPOR PLUG FOR CRYOGENIC STORAGE VESSELS

摘要

A thermal barrier for a Dewar vessel (100) combines an insulate vapor plug (30) and a vapor barrier. The plug (30) is sized so as to define an open space (8) between it and the neck portion of the Dewar vessel (100) to allow venting of vaporous cryogen form the inner vessel (80) of the Dewar vessel (100) through a Dewar opening. The vapor barrier provides an interference between the plug (30) and the neck portion (20) that disrupts venting of vaporous cryogen but does not form an airtight seal that would block venting and cause unacceptable build-up of pressure within the inner vessel. Multiple vapor barriers, especially four or more, provide multiple interferences that create multiple chambers between the plug (30) and the neck portion (20).