A safety shut down valve (also known as an emergency shutdown valve, or ESD) is an actuated valve designed to stop the flow of a hazardous fluid or external hydrocarbons upon the detection of a dangerous event. This provides protection against possible harm to people, equipment or the environment, or the loss of fluid. 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 (such as the mines on their high pressure water) may also require this type of protection system. Safety shut down valves are required by international law on any equipment placed on an offshore drilling rig to prevent catastrophic events.
For fluids, metal seated ball valves are often used as safety shut down valves. The use of metal seated ball valves leads to overall lower costs when taking into account the loss on production, inventory and valve repair costs resulting from the use of soft seated ball valves (which have a lower initial cost).
Straight-through flow valves, such as rotary-shaft ball valves, are typically high-recovery valves. High recovery valves are valves that lose little energy due to low flow turbulence. Flow paths are straight through. Rotary control valves, butterfly valves and ball valves are good examples.
In the Water industry, Safety Shutdown valves are often used and referred to as Excess Flow Shutdown valves. These valves are installed in strategic places on pipelines where a pipe break could result in extensive loss of water (outlets of Reservoirs) and even flooding of Residential or other properties. The most common valve used for these applications are Pilot operated valves such as the Ultra ACV.
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