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Question:

Calculation of Shutdown Valve Instrument Air Supply?

Calculation of Shutdown Valve Instrument Air Supply?

Answer:

Shut down valves I've worked with haven't had an 'Air Flow' for their operation. For the smaller valves, they consist of diaphragm operated valves either held open or closed by pneumatic pressure. The air supply at 25psi to give a diaphragm holding pressure of 15 psi, is via a solenoid valve which dumps the air pressure to either open or close the valve depending upon its function. (That of isolating a system or relieving pressure). The solenoid is actuated by a signal from the shut-down system, and the valve is a 3-way unit which isolates the supply air and vents the pressure off the diaphragm. Other SDV's in my experience, are operated in a similar way but are much larger and are operated by a pneumatic air cylinder and piston with air supplied at 100 psi. Others encountered are ... MOV's...Motor Operated Valves that can be automatically operated from the shutdown system, or Operated Remotely from a safe distance (ROV's).

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