146.What are the fail-safe conditions of control valves, give typical example?

Fail safe conditions of Control valves are Fail-Open and Fail-Close (Depending on the end position reached by control valve on loss of control signal/air supply).Normally Fail open valves are used in Emergency applications like recirculation line or Bypass lines (HP bypass, Heater bypass etc). Valves used for fuel flow are fail close type.