Automation Abbreviations: Introduction
Automation systems use hundreds of short codes and tags to represent instruments, signals, alarms, and control functions.
These short forms are known as Automation Abbreviations, and they appear everywhere on P&ID drawings, control logic diagrams, loop sheets, PLC programs, DCS screens, and SCADA systems.
For students and working engineers, understanding these abbreviations is essential to read drawings correctly, configure instruments, and communicate clearly with operations and maintenance teams.
In this article, we have compiled a complete and updated list of Automation Abbreviations used in industry. The list is organized category-wise to make learning easy and practical.
It covers flow, pressure, level, temperature, control valves, PLC/DCS/SCADA systems, safety and SIL terms, and digital and IIoT-related abbreviations commonly used in modern automation projects.
1) Flow Abbreviations
| Symbol | Description |
|---|---|
| F | Flow (Measured Variable) |
| FE | Flow Element |
| FT | Flow Transmitter |
| FI | Flow Indicator |
| FR | Flow Recorder |
| FC | Flow Controller |
| FIC | Flow Indicating Controller |
| FRC | Flow Recording Controller |
| FCV | Flow Control Valve |
| FV | Flow Valve (Final Control Element for Flow) |
| FS | Flow Switch |
| FSH | Flow Switch High |
| FSL | Flow Switch Low |
| FAH | Flow Alarm High |
| FAL | Flow Alarm Low |
| FAHH | Flow Alarm High-High |
| FALL | Flow Alarm Low-Low |
| FSD | Flow Shutdown |
| FSDH | Flow Shutdown High |
| FSDL | Flow Shutdown Low |
| FY | Flow Relay / I/P / Converter / Computation (Flow loop auxiliary) |
| FQI | Flow Totalizer/Integrator Indicator |
| FQ | Flow Totalizer |
| FYI | Flow Computing / Linearizer (commonly used on DCS) |
| DP (Flow) | Differential Pressure used for Flow (Orifice/Nozzle/Venturi) |
| WIF | Water Induced Flow (commonly used in utilities and site dependent) |
2) Pressure Abbreviations
| Symbol | Description |
|---|---|
| P | Pressure (Measured Variable) |
| PT | Pressure Transmitter |
| PI | Pressure Indicator |
| PR | Pressure Recorder |
| PC | Pressure Controller |
| PIC | Pressure Indicating Controller |
| PRC | Pressure Recording Controller |
| PCV | Pressure Control Valve |
| PV | Pressure Valve (Final Control Element for Pressure) |
| PG | Pressure Gauge |
| PS | Pressure Switch |
| PSH | Pressure Switch High |
| PSL | Pressure Switch Low |
| PSHH | Pressure Switch High-High |
| PSLL | Pressure Switch Low-Low |
| PAH | Pressure Alarm High |
| PAL | Pressure Alarm Low |
| PAHH | Pressure Alarm High-High |
| PALL | Pressure Alarm Low-Low |
| PSD | Pressure Shutdown |
| PSDH | Pressure Shutdown High |
| PSDL | Pressure Shutdown Low |
| PRV | Pressure Regulating Valve |
| PSV | Pressure Safety Valve |
| PSE / RD | Rupture Disc / Rupture Disk |
| PD | Pulsation Dampener |
| DP | Differential Pressure |
| DPT | Differential Pressure Transmitter |
| PDI | Differential Pressure Indicator |
| PDS | Differential Pressure Switch |
| PDSH | DP Switch High |
| PDSL | DP Switch Low |
3) Level Abbreviations
| Symbol | Description |
|---|---|
| L | Level (Measured Variable) |
| LT | Level Transmitter |
| LI | Level Indicator |
| LG | Level Gauge / Sight Glass |
| LR | Level Recorder |
| LC | Level Controller |
| LIC | Level Indicating Controller |
| LRC | Level Recording Controller |
| LCV | Level Control Valve |
| LV | Level Valve (Final Control Element for Level) |
| LS | Level Switch |
| LSH | Level Switch High |
| LSL | Level Switch Low |
| LSHH | Level Switch High-High |
| LSLL | Level Switch Low-Low |
| LAH | Level Alarm High |
| LAL | Level Alarm Low |
| LAHH | Level Alarm High-High |
| LALL | Level Alarm Low-Low |
| LSD | Level Shutdown |
| LSDH | Level Shutdown High |
| LSDL | Level Shutdown Low |
| LLG | Local Level Gauge (plant usage) |
| LL | Liquid Level (general) |
| LIT | Level Indicating Transmitter (common tag style) |
4) Temperature Abbreviations
| Symbol | Description |
|---|---|
| T | Temperature (Measured Variable) |
| TT | Temperature Transmitter |
| TI | Temperature Indicator |
| TR | Temperature Recorder |
| TC | Temperature Controller |
| TIC | Temperature Indicating Controller |
| TRC | Temperature Recording Controller |
| TCV | Temperature Control Valve |
| TV | Temperature Valve (Final Control Element for Temperature) |
| TE | Temperature Element |
| TW | Thermowell |
| TH | Thermostat |
| TAH | Temperature Alarm High |
| TAL | Temperature Alarm Low |
| TAHH | Temperature Alarm High-High |
| TALL | Temperature Alarm Low-Low |
| TSH | Temperature Switch High |
| TSL | Temperature Switch Low |
| TSD | Temperature Shutdown |
| TSDH | Temperature Shutdown High |
| TSDL | Temperature Shutdown Low |
| RTD | Resistance Temperature Detector |
| TC (sensor) | Thermocouple (context-based in plants) |
5) Control & Valves Abbreviations
| Symbol | Description |
|---|---|
| CV | Control Valve |
| XV | On/Off Valve (commonly used for shutdown/isolation) |
| MOV | Motor Operated Valve |
| AOV | Air Operated Valve |
| POV | Pneumatically Operated Valve |
| SOV | Solenoid Operated Valve |
| SDV | Shutdown Valve |
| ESDV | Emergency Shutdown Valve |
| BDV | Blowdown Valve |
| DV | Diverter Valve (site usage) |
| PVSV | Pilot Valve / Solenoid Valve (site usage) |
| POS | Positioner |
| I/P | Current to Pneumatic Converter |
| P/I | Pneumatic to Current Converter |
| FR (air) | Filter Regulator (instrument air set) |
| AFR | Air Filter Regulator |
| NRV / CHV | Non-Return Valve / Check Valve |
| BPR | Back Pressure Regulator |
| PRV | Pressure Reducing/Regulating Valve (context-based) |
| PSV | Pressure Safety Valve |
| DBB | Double Block and Bleed |
| FC / FO / FL | Fail Close / Fail Open / Fail Last |
| HS | Hand Switch |
| HOA | Hand-Off-Auto Switch |
| PB | Push Button |
6) PLC / DCS / SCADA Abbreviations
| Symbol | Description |
|---|---|
| PLC | Programmable Logic Controller |
| DCS | Distributed Control System |
| SCADA | Supervisory Control and Data Acquisition |
| HMI | Human Machine Interface |
| I/O | Input / Output |
| DI | Digital Input |
| DO | Digital Output |
| AI | Analog Input |
| AO | Analog Output |
| RTU | Remote Terminal Unit |
| CPU | Central Processing Unit |
| PSU | Power Supply Unit |
| MCC | Motor Control Center |
| VFD | Variable Frequency Drive |
| VSD | Variable Speed Drive |
| ESD | Emergency Shutdown System/Station (context-based) |
| SOE | Sequence of Events |
| PID | Proportional–Integral–Derivative control |
| SIS | Safety Instrumented System (often separate from BPCS) |
| BPCS | Basic Process Control System |
| JB | Junction Box |
| IS | Intrinsically Safe (context-based) |
7) Safety & SIL Abbreviations
| Symbol | Description |
|---|---|
| SIL | Safety Integrity Level |
| SIS | Safety Instrumented System |
| SIF | Safety Instrumented Function |
| ESD | Emergency Shutdown |
| ESDV | Emergency Shutdown Valve |
| SDV | Shutdown Valve |
| PSD | Process Shutdown (site usage) |
| F&G | Fire & Gas System |
| FSD | Fire Shutdown / Field Shutdown (site usage) |
| HH / LL | High-High / Low-Low Trip philosophy |
| LOPA | Layer of Protection Analysis |
| HAZOP | Hazard and Operability Study |
| PHA | Process Hazard Analysis |
| RRF | Risk Reduction Factor |
| PFDavg | Probability of Failure on Demand (average) |
| PFH | Probability of Failure per Hour |
| IEC 61511 | SIS lifecycle standard (process industry) |
| IEC 61508 | Functional safety standard |
| IS | Intrinsically Safe |
| Ex d / Ex e | Flameproof / Increased Safety (hazardous area) |
8) Digital & IIoT Abbreviations
| Symbol | Description |
|---|---|
| IIoT | Industrial Internet of Things |
| IoT | Internet of Things |
| HART | Highway Addressable Remote Transducer |
| WirelessHART | Wireless HART network |
| Modbus RTU/TCP | Industrial comms protocol |
| Profibus DP/PA | Fieldbus protocol (DP/Process Automation) |
| Profinet | Industrial Ethernet protocol |
| EtherNet/IP | Industrial Ethernet protocol |
| FOUNDATION Fieldbus | Digital fieldbus protocol |
| OPC UA | Secure data exchange standard |
| MQTT | Lightweight IIoT messaging |
| REST API | Web interface for data exchange |
| Edge | Edge Computing (near-field processing) |
| Gateway | Protocol / network gateway |
| Tag | Single data point name in SCADA/DCS |
| Historian | Time-series storage system |
| Asset Mgmt | Device/asset management system |
| Cyber OT | Operational Technology Cybersecurity |
Understanding Automation Abbreviations is not just about memorizing short forms but it is about correctly reading systems, avoiding mistakes, and working confidently with automation drawings and control systems.
Whether you are a student learning instrumentation, a technician working on-site, or an engineer designing control logic, these abbreviations form the common language of the automation industry.
This category-wise list brings together the most commonly used abbreviations across flow, pressure, level, temperature, control valves, PLC/DCS/SCADA systems, safety, SIL, and digital automation.
Keeping this reference handy will save time, improve communication, and help you work more accurately in real industrial environments as automation systems continue to evolve.
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