NSN 4820-01-660-6663

A valve consisting of a single deadweight loaded disk, or two deadweight loaded disks each with a seperate seat. It is specifically designed for the relief of small pressure and vacuum conditions within a tank or other container to or from the atmosphere. The center of a single deadweight loaded disk may contain a spring loaded disk forming an additional seat or aperture. It may be spring loaded and/or equipped with a manual unloader on either the pressure or vacuum side. Exclude valve, vacuum breaking.