NSN 4820-01-172-6981

A thin, circular, metallic or nonmetallic item with a flat or prebulged cross-sectional shape, designed to rupture at a predetermined pressure to prevent damage to hydraulic or pneumatic systems, or the like. It may include multiple pieces, such as a retainer ring, disk and vacuum support. It can be used independently or as a component part of a head, safety, pressure relief. For items furnished with a holder, see head and disk, safety, pressure relief. For items without a rupture pressure rating, see disk, solid, plain. Excludes diaphragm, valve, flat; diaphragm, valve, special shaped; disk, valve; and insulator, disk.