P&ID Symbols and Meanings

P&ID stands for "Piping and instrumentation diagram." It is a very important industrial diagram representing the exact working of the processes in an industrial plant. It uses specific P&ID symbols to visually show the processes, the equipment, and their connection and relationship with each other. The main components are P&ID symbols representing pumps, motors, pumps, compressors, and towers.

1. What Are P&ID Symbols

As we already discussed, P&ID diagrams are made with specific and standard shapes and symbols. As this diagram covers many diagrams as the variety in industries is very vast, many symbols are required. These diagrams provide a map for the engineering system's design which is later helpful in problem identification and solving. The most popular instruments are actuators, equipment, flow elements, instrumentation, piping fittings, valves, and more. P&ID symbols are industry-standard symbols, including instruments, equipment, heat exchangers, vessels, pipe, motors, and interconnecting lines.


2. P&ID Symbols Explained

P&ID symbols are categorized according to their functions and industrial uses. The major categories are Piping, instrumentation, pumps, valves, vessels, heat exchangers, compressors, and equipment.

2.1 Piping P&ID Symbols

Piping P&ID symbols represent the equipment that transports fluid substances. There are multiple types of pipes that make them eligible for a separate category. It can be simple, multi-line, separators, connectors, end caps, flanges, reducers, and coupling. The list of piping symbols is as follows.

Piping P&ID Symbols

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2.2 Pumps P&ID Symbols

Pumps are an essential part of the majority of industrial plants that need pumps. These pumps can be used for suction, compression, moving fluid, and also for pressure control. There are many p and id symbols for pumps. Here is a list.

Pumps P&ID Symbols

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2.3 Valves P&ID Symbols

Valves in the engineering design are for control flow. The two categories are Actuators and Self-Regulated Relief Valves. The specific symbols are:

Valves P&ID Symbols

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2.4 Vessels P&ID Symbols

A vessel is used to show containers to store fluids. The larger vessels P&ID symbol group includes tanks, cylinders, columns, bags, and others.

Vessels P&ID Symbols

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2.5 P&ID Instrumentation Symbols

Instrumentation symbols in a P&ID are standardized to ensure consistent control and automation. It helps in the identification of the part and broad base understanding of the process. Common instrumentation symbols are meters, transmitters, sensors, indicators, and other measurements and recordings.

P&ID Instrumentation Symbols

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2.6 Heat Exchangers P&ID Symbols

A heat exchanger transfers heat between different surfaces, fluids, mediums, or areas. These devices can be used in both cooling and heating processes. The symbols include boilers, condensers, and other heat exchanging devices.

Heat Exchangers P&ID Symbols
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2.7 Compressors P&ID Symbols

Compressors and blowers move air or gas through an operational process. Compressors operate at a high pressure-to-volume ratio, while blowers operate at a low-pressure ratio. The list of compressor p and id symbols is listed below.

Compressors P&ID Symbols
Click on the image to edit. Source: EdrawMax Online


2.8 Motors P&ID Symbols

Motors are so important that you will even find them in toy cars. So no industrial process model can be made without motors. Motors are available in many different variants. Generators are also included in this category. Common motor and generator P&ID symbols are:

Motors P&ID Symbols
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2.9 Instruments P&ID Symbols

An instrument is a device that measures and controls different parameters such as flow, temperature, angle, or pressure. This broad category includes indicators, transmitters, recordings, controllers, and elements.

Instruments P&ID Symbols
Click on the image to edit. Source: EdrawMax Online Instruments P&ID Symbols
Click on the image to edit. Source: EdrawMax Online Instruments P&ID Symbols
Click on the image to edit. Source: EdrawMax Online


There is a bubble mark on each instrument that represents the proper specification of the instrument. How to read these labels? These labels are divided into three parts.

1. A horizontal line. It can be found in three types.

  • A single horizontal line shows that the instrument is located on the main control panel and available to the panel operator.
  • No horizontal line represents it is installed in the field and access to field operators.
  • ●A dashed horizontal line is used when the instrument is inaccessible in the field. It can be hidden or password-protected on the control system.

2. The label is a combination of three letters that shows the parameter being measured, what the instrument does, and the instrument. So a label "FIC" shows;

  • F -> The parameter being measured is Flow here.
  • I -> What the instrument does, it is Indicator here.
  • C-> Instrument, it is Controller here.

3. The third figure that comes under the horizontal line is the Control loop.

Instruments P&ID Symbols


P&ID Symbols Abbreviations

Analyzer Element (Chemical Composition) AE
Air Operated Valves AOV
Burner Element (flame detector) BE
Conductivity Recorder CR
Differential Pressure DP
Density Transmitter DT
Flow Controller FC
Flow Control Valve FCV
Flow Element FE
Flow Sight Glass FG
Flow Hand Control (manual) FHC
Hand Switch in Flow Loop FHS
Flow Indicator FI
Flow Indicating Controller FIC
Flow Meter FM
Flow Quantity Recorder FQR
Flow Quantity Indicator FQI
Flow Recorder FR
Flow Recorder Controller FRC
Flow Switch FS
Flow Transmitter FT
Flow Transducer FTD
Hand Operated Control Valve HCV
Hand Switch HS
Level Controller LC
Level Control Valve LCV
Level Gage Glass LG
Level Hand Control (manual) LHC
Level Indicator LI
Level Indicating Controller LIC
Level Recorder LR
Level Switch LS
Level Transmitter LT
Level Transducer LTD
Motor Operated Valve MOV
Motion Transmitter MT
Pressure Alarm PA
Pressure Controller PC
Pressure Control Valve PCV
Differential Pressure Indicator PDI
Ph Transmitter PHT
Pressure Indicator PI
Press. Indicating Controller PIC
Press. Indicating Transmitter PIT
Pressure Recorder PR
Pressure Switch PS
Pressure Transmitter PT
Pressure Transducer PTD
Pressure Relief Valve PZV
Temp. Indicating Controller TIC
Temp. Recorder TR
Steam Trap or Airvent TRAP
Temp. Switch TS
Temp. Switch Alarm TSA
Temp. Transmitter TT
Temp. Transducer TTD
Thermowell TW
Weight Measuring Element WE
Annunciator XA
Vibration Detector XVE
Vibration Switch XVS


4. P&ID Symbols PDF

We have created a printable p&id symbols PDF file that you can download and print if you wish to have a quick reference to the p&id symbols list. You can download the file by clicking on the image below.

P&ID Symbols PDF
Click the image to download P&ID Symbols PDF.


5. Tips for Using P&ID Symbols

P&ID symbols have such a great variety that it is very difficult to manage them or even remember them. An easy-to-use software program that helps you create P&ID diagrams that allow you to draw, export, and format your drawings effectively and efficiently. EdrawMax Online is an excellent program to draw these diagrams as it has a complete range of symbols and notations under the process engineering category. You can simply drag and drop the symbols on the canvas according to your drawing needs. Here are some tips for using EdrawMax Online for drawing P&ID drawings.

1. In the new drawing window, click the symbols library button on the sidebar and navigate to process engineering items. Under this category, you will find all P&ID symbols. P&ID Symbols

2. If you want to import any specific symbol for your needs because it is not available in the library, use the import option. Click on the import icon in the sidebar. In the pop-up window, go to the tab according to the symbol file format that you want to import. Further details and the complete process is shown in this video. YouTube.


6. Conclusion

A piping and instrumentation diagram (P&ID) shows process equipment and instrumentation used to control the process. It is important to use the standard symbols based on International Society Automation (ISA) Standard S5.1. You can find all P&ID symbols in the EdrawMax symbols library as well. EdrawMax Online is an excellent tool because of its wide support and extensive features like comprehensive symbols library, P&ID examples, export in multiple formats, and import of symbols and libraries. It is available for free online and desktop with maximum feature support.

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