ISA Certified Control Systems Technician(CCST)Program

摘要

A loss of power to FIC 900,which is a flow controlling mechanism and opens and closes the valve,causes the valve to automatically close-Fail-Closed(FC).Symbols for failure modes are on the line between the valve symbol and the actuator symbol.The arrow pointing down,as it does here,indicates FC.If the arrow had pointed up,that would indicate Fail-Open.