(under subclass 456) Apparatus in which the valve is biased toward the closed or cut-off condition but is restrained from closing by a latch or similar means, which latch will release the valve for closing in response to a change in fluid condition within the apparatus.
SEE OR SEARCH CLASS
251, Valves and Valve Actuation,
73, for fluid pressure trip actuation wherein the source of fluid for actuating the trip is not necessarily the line which is controlled, and see the search notes thereto.
