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Instrumentation Symbol Standards
This document explains how to read instrumentation symbols that frequently appear in instrumentation drawings. For further details, please read the relevant standards documentations.
Instrumentation symbol standards are established by ISO 3511/1-1977*¹ and JIS8204-1983*². For instrumentation equipment (1-loop) that carries out a series of functions, ISO/JIS defines 1 character symbol (an alphanumeric using capital letters), or a graphic symbol that expresses the same concepts in a drawing.
*¹: ISO 3511/1-1977 Process measurement control functions and instrumentation – Symbolic representation –
Part1: Basic requirements
*²: JIS8204-1983 instrumentation symbols
The following shows examples of character and graphical symbols used for instrumentation.
Examples of Instrumentation Character Symbols
As shown in tables 1 and 2, character symbols consist of variable symbols, function symbols (and combinations thereof), and individual symbols (loop numbers), in that order.
| Variable Symbol | Function Symbol | Individual Symbol (Loop Number) | Description |
|---|---|---|---|
| T | I | 1012 | TIC stands for temperature indicating controller |
| F | R | 1013 | FRC stands for flow recording controller |
| P | T | 1014 | PT stands for pressure transmitter |
Examples of Instrumentation Graphical Symbols
Graphical symbols consist of the symbols in table 3 and combinations thereof.
Common Instrumentation Character and Graphical Symbols
Table 1: Variable symbols
| Symbol | Variable | Symbol | Variable |
|---|---|---|---|
| D | Density or specific gravity | P | Pressure or vacuum |
| E | Electrical quantity | S | Speed, revolutions, or frequency |
| F | Flow | T | Temperature |
| L | Level | V | Viscosity |
| M | Moisture or humidity | W | Weight or force |
Table 2: Function symbols
| Symbol | Measurement Equipment Format or Function |
Symbol | Measurement Equipment Format or Function |
|---|---|---|---|
| A | Alarm | R | Recording |
| C | Correction | S | Sequence control |
| E | Detection | T | Transfer or conversion |
| I | Indication | Y | Computation |
| Q | Integration | Z | Sagety or emergency |
Table 3: Common graphical instrumentation symbols
Further reading:
1. ISO 3511/1-1977 Process measurement control functions and instrumentation – Symbolic representation – Part1: Basic requirements
2. JIS8204-1983 instrumentation symbols
