This specification covers self-contained automatic shut-off valves (also known as Excess Flow Valves) for air or nitrogen service. They are intended to be installed as safety devices to quickly and automatically shut-off flow under certain excess flow conditions caused by a downstream failure or casualty such as a hose rupture. The valves stated in this specification in inch-pounds units are to be regarded as the standard. The SI equivalent shown in parentheses are provided for information only.