Regarding on-off control valves and fail-open/fail-close functions
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I would like to know the difference between \"air-open\" and \"air-close\", as well as between \"fault-open\" and \"fault-close\"; what do the letters O and C mean (does O indicate air-open or fault-open, and does C indicate air-close or fault-close)? Also, where are the control valves that enable air-open/fault-open or air-close/fault-close functions installed? Are there any relevant standards governing this, or if anyone has relevant information, please send it to me
FC: Fault off (corresponds to air open) FO: Fault on (corresponds to air close)
Does F mean failure?
Yes, the installation location is designed by the process engineering team based on the process requirements.
Okay, thank you. I suddenly understood it – once I figured out the meaning of those letters, everything became clear, and there was no need to memorize them deliberately
Generally, FC stands for Fault Close (corresponding to air open), while FO stands for Fault Open (corresponding to air close)
Well, it’s originally an abbreviation of an English word; there’s no need to memorize it by force. . . FO: Failure Open, in the open state due to a fault ； FC: Failure Closed, fault resolved ； There’s also an FL: Failure Locked, meaning the valve position remains unchanged in case of a fault.
FC: Fault close, which means normally closed; air-operated open. FO: Fault open, which means normally open; air-operated closed