Fail closed (FC), letter form
ISA 5.1 / PIP PIC001
Drawn as
The letters "FC" written just below (sometimes beside) a valve body.
Meaning
On loss of air, power or signal the valve goes fully closed. Typical for ESD valves, feed and fuel valves. Set the valve's fail action to FC.
Variants
- Some legends write "AO/AC" (air to open / air to close) instead. Air-to-open means fail closed
- The fail position is the shelf (no-air) position, not the normal operating position
Tags
FC
Not physical hardware. Read it, then skip it in the 3D model.