What F means on a P&ID.
Flow is the most common first letter in process drawings because almost every BPCS loop ties back to a flow measurement. FF, flow ratio is sometimes used to denote ratio control loops where two flows are constrained to a programmed ratio.
Also stands for.
- Flow rate
- Flow ratio, when prefixed FF
Common second letters.
| Tag | Meaning |
|---|---|
| FT | Transmitter, FT. Flow transmitter |
| FI | Indicator, FI. Flow indicator |
| FIC | Indicator plus controller, FIC. Flow indicating controller |
| FY | Computing relay or transducer, FY. Flow signal computing element |
| FE | Sensor or primary element, FE. Flow element, e.g. Orifice plate |
| FAL | Alarm low, FAL. Flow alarm low |
| FAH | Alarm high, FAH. Flow alarm high |
| FSH | Switch high, FSH. Flow switch high |
Example tags.
| Tag | Meaning |
|---|---|
| FT-101 | Flow transmitter on loop 101 |
| FIC-2103 | Flow indicating controller, train 21, loop 03 |
| FE-405 | Flow element, orifice plate, vortex meter, etc. On loop 405 |
| FY-101A | Flow computing relay, redundant A, loop 101 |
Typical placement.
Inline on a process line, drawn as a circle bisected by the pipe with the tag inside or adjacent. The first-letter F is paired with a second-letter that describes the function, transmitter, indicator, controller, switch, alarm, computing relay.
Common questions
What does the ISA 5.1 first letter F stand for?
In ISA 5.1, the first letter F stands for Flow. It can also stand for Flow rate, Flow ratio, when prefixed FF.
How is letter F typically used on a P&ID?
Inline on a process line, drawn as a circle bisected by the pipe with the tag inside or adjacent. The first-letter F is paired with a second-letter that describes the function, transmitter, indicator, controller, switch, alarm, computing relay.
What second letters commonly follow F in ISA 5.1 tags?
Common combinations include FT (Transmitter, FT. Flow transmitter), FI (Indicator, FI. Flow indicator), FIC (Indicator plus controller, FIC. Flow indicating controller), FY (Computing relay or transducer, FY. Flow signal computing element), FE (Sensor or primary element, FE. Flow element, e.g. Orifice plate), FAL (Alarm low, FAL. Flow alarm low).
What are example ISA 5.1 tags starting with F?
FT-101 (Flow transmitter on loop 101); FIC-2103 (Flow indicating controller, train 21, loop 03); FE-405 (Flow element, orifice plate, vortex meter, etc. On loop 405).
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