What are the requirements for emergency shutdown valves (ESD/ESV)?

ESD valve requirements: fast closing time (typically 2-10 seconds), reliable fail-safe action, high availability (SIL rated as needed), tight shutoff, and manual override capability. Components: quick-exhaust or dump valve (fast depressurization), lockup systems, limit switches (position indication), and partial stroke testing capability. Testing: regular partial stroke tests (quarterly typical), full stroke tests during shutdown. Documentation: SIS datasheet, proof test procedures, and failure rate data. Design to fail-safe on loss of power, air, or signal. May require redundant solenoids or voting schemes for high SIL levels.