Difference between "CLASS" and "LBS" in "Valves"
Sharing philosophy of Automatic Block Valve and emergency block valve.
Many plants use gate valves for isolating units at the battery limits etc. Large gate valves require many turns of the handwheel to open. Automated valves may use electric actuators to permit remote operation. An operator may also push buttons to open or close such valves. Usually a manual hand wheel is also provided as an override when power is lost. Such a valve would fall into the automated isolation valve description. Some quarter turn pneumatic valves are also operated using a vane actuator (perhaps gas over oil with stored energy) or double acting pneumatic actuator (perhaps with an air storage cylinder and double check valves on the supply). Lacking a spring these automated valves would not be suitable as emergency shutdown valves.
A pneumatic actuator on a quarter turn ball or butterfly valve is more common for an emergency shutdown valve. The emergency shutdown valve should be able to close with no power or air supply.
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