Technical knowledge of Shut down valve and Blow down valve

A S hut 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

Shutdown valves are primarily associated with the petroleum industry although other industries may also require this type of protection system.

A Blow down valve (also referred to as BDV or Blow down valve is an actuated valve designed to depressurized process pressure upon the detection of a dangerous event. This provides protection against possible harm to people, equipment or the environment. Blowdown 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

Shutdown / Blow down valves are primarily associated with the petroleum industry although other industries may also require this type of protection system.

SDV: ( closed valve)

It was used in plant inlet & outlet places.whenever plant was partially OR total shutdown condition, at that time plant was not disturbed from/to another process,closed the disturbed process through SDV".

BDV : (opened valve)
It was used in sudden flare OR depressurized condition,relief that pressure( to avoid dangerous condition) used this valve.