Shut down valve

A shut down valve (also referred to as SDV or Emergency Shutdown Valve, ESV, ESD, or ESDV) is an actuated valve designed to stop the flow of a hazardous fluid upon the detection of a dangerous event. This provides protection against possible harm to people, equipment or the environment. Shutdown valves form part of a Safety Instrumented System. The process of providing automated safety protection upon the detection of a hazardous event is called Functional Safety