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Free AutoCAD instrumentation symbols (DWG), ISA 5.1 style

Instrumentation symbols (ISA 5.1 style): 133 ready-made AutoCAD blocks (DWG), free to download and use in your own projects, as a ZIP or one symbol at a time.

133 symbols for P&ID and loop drawings as ready-to-use AutoCAD blocks, drawn after the symbol tables of ISA 5.1: instrument bubbles for discrete, shared display and control, safety instrumented and computer functions in five mounting locations; transmitters and secondary instruments; instrument connections and signal lines; valve bodies and actuators; and complete control valves. The tag letters, the loop number and the instrument data sit in attributes, so an instrument index can be read straight from the drawings.

Free library: version 1.2, updated November 9, 2026 · Pro library: version 1.0, updated November 9, 2026 · Check out what's changed

ISA 5.1 Pro: 152 more symbols

Beyond the 133 free symbols above, Pro adds five more sections of the standard as AutoCAD blocks: qualifying symbols, fundamental items, transmission path, terminals and connectors, and semiconductor devices. One licence covers every section, and the free library stays free.

Two ways to get Pro

Pro library

$49

  • DWG files with all 152 Pro symbols, one ZIP per section
  • Plain DWG files, no add-in needed
  • Includes the 133 symbols of the free library as a DWG

Pro palette for AutoCAD

$59

  • Everything in the library: the DWG files of every Pro section are included
  • A palette inside AutoCAD: search by name in 9 languages and place a symbol with one click
  • All 285 symbols; 12 of them work for free, so you can try before you buy
  • AutoCAD 2021 to 2027 on Windows
See the palette

What's inside this Pro library

SectionSymbolsWhat it coversFile in your download
ISA 5.1 instrumentation Pro symbols152Primary elements, Accessories, Regulators and safety devices, Functional diagramming symbols, Signal processing blocks, Electrical schematic symbolsISA51-Instrumentation-Pro-Symbols.zip
Total152
  • Every symbol is an AutoCAD block, drawn in millimetres at 1:1 and named IEEE_GROUP_NAME; insert it at scale 1.
  • Each block has two invisible attributes, DESC (the symbol name) and REMARKS (free text). All geometry is on layer SYMBOL.
  • Each DWG has a CATALOG layout with all its symbols on one sheet, ready to plot to PDF, and a README.txt lists every block.
  • Plain DWG files in AutoCAD 2018 format, plus a second ZIP per section in AutoCAD 2010 format. No add-in is needed.
  • The 133 symbols of the free library come in the same download as their own DWG, so you have the whole set in one place.

Pro library licence

$49

For one person

Education: $24.50

  • Pay once
  • Includes the free IEEE 315 library

Student or teacher?

Half price ($24.50) for one year with your school e-mail address. Buy again next year to renew.

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What you get

  • All 152 symbols of the sections on this page, as AutoCAD blocks in DWG files
  • The free IEEE 315 library with its 79 symbols, in the same download
  • Every section as a ZIP in AutoCAD 2018 format and in AutoCAD 2010 format
  • Sections added later come with the same purchase
  • The free IEEE 315 library stays free and unchanged.
  • A perpetual licence: pay once, keep the files.

Read the full licence

Refund policy

  • Free · 133 symbols

  • ISA 5.1 instrumentation Pro symbols · 152

ISA 5.1 instrumentation Pro symbols 152

152 further symbols of this library for Pro, in the same blocks, layers and attributes as the free ones.

152 of 152 symbols

Sample drawings made with this library

Related symbol libraries

Missing a symbol? Tell us which one.

Attributes for parts lists

An instrument bubble has two visible attributes inside it: TAG_FUNC for the function letters (for example FIC) and LOOP_NO for the loop number (for example 101). Everything else is an invisible attribute: SERVICE, AREA, RANGE, UNIT, SIGNAL_TYPE, IO_ADDRESS, CABINET, PID_NO, MANUFACTURER, MODEL and DATASHEET_NO.

Valves show VALVE_TAG and SIZE; control valves also carry FAIL_POSITION, CV and ACTUATOR. Actuators show a TAG.

How to use the library

  1. Unzip the file and open the DWG. Copy the symbols you need into your P&ID, or drag the blocks in from DesignCenter (ADCENTER).
  2. Bubbles are inserted by their centre. Valve bodies and control valves are inserted at the left pipe connection; both connections are on a 5 mm grid, so a valve drops onto a pipe line drawn on the grid. A separate actuator is inserted at the point on the valve stem.
  3. Pick the bubble that matches the function and the location. The line across the bubble shows where the instrument is: no line for the field, one line for the main panel, two lines for an auxiliary or local panel, and dashed lines for the rear of a panel or a field cabinet.
  4. Double-click the block (or run EATTEDIT) and fill in the function letters, the loop number and the instrument data.

About ISA 5.1

ISA 5.1 (ANSI/ISA-5.1-2009) is the standard for instrumentation symbols and identification on P&IDs and loop diagrams. In its bubble table a circle is a discrete instrument, a circle in a square is shared display and shared control (the primary choice, the basic process control system such as a DCS or a PLC), a diamond in a square is the alternate choice or a safety instrumented system, and a hexagon is a computer system or software function.

These symbols are our own drawings after the symbol tables of the standard. They are not copied from it, because it is a paid publication, and the library is not certified against it. Company and project standards often differ in details such as the bubble size and the number of location lines; change the blocks if yours do.

What changed in each version

Version 1.2 · November 9, 2026

Removed: 152

Version 1.1 · October 19, 2026

New symbols (89)

Solenoid valve, 4-way 5-port · Pilot light · 87 more

Frequently asked questions

Are these symbols ISA 5.1 compliant?
They are drawn after the common ISA 5.1 forms, not checked clause by clause and not certified. The standard is a paid publication that we have not copied. If a client requires strict conformance, compare the shapes with your copy of the standard.
How do I show that a function runs in the DCS or in the PLC?
Use the shared display and shared control bubble (a circle inside a square) for a function in the basic process control system, whether that is a DCS or a PLC, a hexagon for a function in computer software and a diamond inside a square for the safety instrumented system. The line across the bubble shows where it is mounted or displayed. PLC I/O modules have no standard drawing: every manufacturer has its own module pictures, so they are not part of this library.
Does the library contain every symbol of ISA 5.1?
No. It covers the main symbol tables: bubbles, transmitters, secondary instruments, connections, signal lines, valve bodies, actuators and control valves. Primary elements, regulators, accessories and safety devices, the electrical symbols and the binary logic and function symbols are not in the free library.
Can I use the symbols in commercial projects?
Yes. They are free to use and modify in your own projects, including commercial ones. They are provided as is, without warranty. Please do not redistribute or resell the library; see the library terms.
Can I change the bubble size or add attributes?
Yes. Open the DWG, edit a block with BEDIT to change it or add attributes, and save. To update drawings that already contain the block, run ATTSYNC or replace the block. Make a backup first: attribute values can be lost if ATTSYNC is used carelessly.
Where do I find a ready-made set of these symbols for AutoCAD?
AutoCAD itself ships only a small set of sample blocks, so a full symbol set has to come from a library. Download the ZIP on this page and open the DWG: every symbol is a block. Insert one with INSERT (Blocks palette, Libraries tab, then pick the DWG) or drag it from DesignCenter (ADCENTER). You can also download a single symbol on its own.