ISA 5.1 Table 2 - Typical Letter Combinations | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Controller | Readout Devices | Switches and Alarm Devices* | Transmitters | ||||||||||
| First Letter | Initial or Measured Variable | Recording | Indicating | Blind | Self Actuated Control Valve | Recording | Indicating | High | Low | Combo | Recording | Indicating | Blind |
| A | Analysis | ARC | AIC | AC | - | AR | AI | ASH | ASL | ASHL | ART | AIT | AT |
| B | Burner/ Combustion | BRC | BIC | BC | - | BR | BI | BSH | BSL | BSHL | BRT | BIT | BT |
| C | User's Choice | - | - | - | - | - | - | - | - | - | - | - | - |
| D | User's Choice | - | - | - | - | - | - | - | - | - | - | - | - |
| E | Voltage | ERC | EIC | EC | - | ER | EI | ESH | ESL | ESHL | ERT | EIT | ET |
| F | Flow Rate | FRC | FIC | FC | FCV | FR | FI | FSH | FSL | FSHL | FRT | FIT | FT |
| FQ | Flow Quality | FQRC | FQIC | - | - | FQR | FQI | FQSH | FQSL | - | - | FQIT | FQT |
| FF | Flow Ratio | FFRC | FFIC | FFC | - | FFR | FFI | FFSH | FFSL | - | - | - | - |
| G | User's Choice | - | - | - | - | - | - | - | - | - | - | - | - |
| H | Hand | - | HIC | HC | - | - | - | - | - | HS | - | - | - |
| I | Current | IRC | IIC | - | - | IR | II | ISH | ISL | ISHL | IRT | IIT | IT |
| J | Power | JRC | JIC | - | - | JR | JI | JSH | JSL | JSHL | JRT | JIT | JT |
| K | Time | KRC | KIC | KC | KCV | KR | KI | KSH | KSL | KSHL | KRT | KIT | KT |
| L | Level | LRC | LIC | LC | LCV | LR | LI | LSH | LSL | LSHI | LRT | LIT | LT |
| M | User's Choice | - | - | - | - | - | - | - | - | - | - | - | - |
| N | User's Choice | - | - | - | - | - | - | - | - | - | - | - | - |
| O | User's Choice | - | - | - | - | - | - | - | - | - | - | - | - |
| P | Pressure/ Vacuum | PRC | PIC | PC | PCV | PR | PI | PSH | PSL | PSHL | PRT | PIT | PT |
| PD | Pressure, Differential | PDRC | PDIC | PDC | PDCV | PDR | PDI | PDSH | PDSL | - | PDRT | PDIT | PDT |
| Q | Quality | QRC | QIC | - | - | QR | QI | QSH | QSL | QSHL | QRT | QIT | QT |
| R | Radiation | RRC | RIC | RC | - | RR | RI | RSH | RSL | RSHL | RRT | RIT | RT |
| S | Speed/ Frequency | SRC | SIC | SC | SCV | SR | SI | SSH | SSL | SSHL | SRT | SIT | ST |
| T | Temperature | TRC | TIC | TC | TCV | TR | TI | TSH | TSL | TSHL | TRT | TIT | TT |
| TD | Temperature, Differential | TDRC | TDIC | TDC | TDCV | TDR | TDI | TDSH | TDSL | - | TDRT | TDIT | TDT |
| U | Multivariable | - | - | - | - | UR | UI | - | - | - | - | - | - |
| V | Vibration | - | - | - | - | VR | VI | VSH | VSL | VSHL | VRT | VIT | VT |
| W | Weight/ Force | WRC | WIC | WC | WCV | WR | WI | WSH | WSL | WSHL | WRT | WIT | WT |
| WD | Weight/ Force Differential | WDRC | WDIC | WDC | WDCV | WDR | WDI | WDSH | WDSL | - | WDRT | WDIT | WDT |
| X | Unclassified | - | - | - | - | - | - | - | - | - | - | - | - |
| Y | Event/ State/ Presence | - | YIC | YC | - | YR | YI | YSH | YSL | - | - | - | YT |
| Z | Position/ Dimension | ZRC | ZIC | ZC | ZCV | ZR | ZI | ZSH | ZSL | ZSHL | ZRT | ZIT | ZT |
| ZD | Gauging/ Deviation | ZDRC | ZDIC | ZDC | ZDCV | ZDR | ZDI | ZDSH | ZDSL | - | ZDRT | ZDIT | ZDT |
ISA 5.1 Table 2 - Typical Letter Combinations | ||||||||
|---|---|---|---|---|---|---|---|---|
| First Letter | Initial or Measured Variable | Solenoid, Relay, Computing Device | Primary Element | Test Point | Well or Probe | Viewing Device, Glass | Safety Device | Final Element |
| A | Analysis | AY | AE | AP | AW | AV | ||
| B | Burner/ Combustion | BY | BE | - | BW | BG | - | BZ |
| C | User's Choice | - | - | - | - | - | - | - |
| D | User's Choice | - | - | - | - | - | - | - |
| E | Voltage | EY | EE | - | - | - | - | EZ |
| F | Flow Rate | FY | FE | FP | - | FG | - | FV |
| FQ | Flow Quality | FQY | FQE | - | - | - | - | FQV |
| FF | Flow Ratio | - | FE | - | - | - | - | FFV |
| G | User's Choice | - | - | - | - | - | - | - |
| H | Hand | - | - | - | - | - | - | HV |
| I | Current | IY | IE | - | - | - | - | IZ |
| J | Power | JY | JE | - | - | - | - | JV |
| K | Time | KY | KE | - | - | - | - | KV |
| L | Level | LY | LE | - | LW | LG | - | LV |
| M | User's Choice | - | - | - | - | - | - | - |
| N | User's Choice | - | - | - | - | - | - | - |
| O | User's Choice | - | - | - | - | - | - | - |
| P | Pressure/ Vacuum | PY | PE | PP | - | - | PSV | PV |
| PD | Pressure, Differential | PDY | PE | PP | - | - | - | PDV |
| Q | Quality | QY | QE | - | - | - | - | QZ |
| R | Radiation | RY | RE | - | RW | - | - | RZ |
| S | Speed/ Frequency | SY | SE | - | - | - | - | SV |
| T | Temperature | TY | TE | TP | TW | - | TSE | TV |
| TD | Temperature, Differential | TDY | TE | TP | TW | - | - | TDV |
| U | Multivariable | UY | - | - | - | - | - | UV |
| V | Vibration | VY | VE | - | - | - | - | VZ |
| W | Weight/ Force | WY | WE | - | - | - | - | WZ |
| WD | Weight/ Force Differential | WDY | WE | - | - | - | - | WDZ |
| X | Unclassified | - | - | - | - | - | - | - |
| Y | Event/ State/ Presence | YY | YE | - | - | - | - | YZ |
| Z | Position/ Dimension | ZY | ZE | - | - | - | - | ZV |
| ZD | Gauging/ Deviation | ZDY | ZDE | - | - | - | - | ZDV |
Other Possible Combinations:
- FQ (Restriction Orifice)
- FRQ, HIK (Control Stations)
- FX (Accessories)
- TJR (Scanning Recorder)
- LLH (Pilot Light)
- PFR (Ratio)
- KQI (Running Time Indicator)
- QQI (Indicating Counter)
- WKIC (Rate-of-Weight-Loss Controller)
- HMS (Hand Momentum Switch)
- A (Alarm), a announcing device, can be used in the same fashion as S (Switch), a actuating device.
