ANSI/ISA 5.1-2022: Instrumentation Symbols and Identification

Instrumentation Symbols in a Diagram Adhering to ANSI/ISA 5.1-2022: Instrumentation Symbols and Identification

In many industries, like oil and gas, engineers create a blueprint for equipment and control layout, which is called a Piping and Instrumentation Diagram (P&ID), and ANSI/ISA 5.1-2022: Instrumentation Symbols and Identification specifies the procedure to do so.

ANSI/ISA 5.1-2022 Standard for Instrumentation Symbols and Identification

ANSI/ISA 5.1-2022 establishes uniform means of depicting and identifying instruments or devices. The standard species the inherent functions, systems, and applications of instruments used for measurement, monitoring, and control. The goal of ANSI/ISA 5.1-2022 is to meet the procedures of various users who need to identify and graphically depict measurement and control equipment and systems.

The symbols and identification methods set forth in this standard are intended to serve as conceptualizing aids, design tools, teaching devices, and concise and specific means of communication in all types of technical, engineering, procurement, construction, and maintenance documents. This largely includes piping and instrumentation diagrams (P&IDs),

Piping and Instrumentation Diagrams

Piping and Instrumentation Diagrams (P&IDs) use specific instrumentation symbols to show the connectivity of equipment, piping, sensors, and valves within a control system, and they are most commonly used in engineering. These instrumentation symbols can represent actuators, sensors, and controllers. Not all P&ID elements are standardized, but the instrumentation symbols follow a standard set by ANSI/ISA 5.1-2022.

What are Tag Numbers?

A tag number with a circle around it indicates stand alone, physical instruments. When a first letter is used in instrumentation symbols, e.g., Pressure Indicator Controller (PIC), it defines the measured or initiating variables. Examples include Analysis (A), Flow (F), Temperature (T), and Pressure (P). The second letter tells the type of device being used, such as Indicator (I), Record (R), and Transmit (T). The third, fourth, or fifth letter tells the function of the component.

Examples of Instrumentation Symbols

To read and understand engineering fluid diagrams and prints, usually referred to as piping and instrumentation diagrams (P&IDs), a user must be familiar with basic symbols. Here are some examples of instrumentation symbols and their use:

  • Centrifugal pumps are used to transport fluids to the hydrodynamic energy of the fluid flow. Centrifugal pump converts the input power to kinetic energy in the liquid by accelerating the liquid by an impeller.
  • Vacuum pump is a device that removes gas molecules from a sealed volume in order to leave behind a partial vacuum.
  • Gear pump uses the meshing of gears to pump fluid by displacement.
  • Controller has an output that varies to regulate a controlled variable in a specific way.
  • Control valve directly manipulates the flow of one or more fluid process streams.
  • Pressure indicator control regulates positive or negative vacuum pressure.
  • Flow control valve regulates the speed of motors or cylinders within in a system.
  • Converter receives information as one form of an instrument signal and transmits an output signal as another form, such as a current-to-pneumatic signal converter.
  • Condenser is a device for reducing a gas or vapor to a liquid.
  • Furnace is a device used for heating.
  • Boiler is a closed vessel in which water or other fluid is heated. The fluid does not necessarily boil.
  • Motor is a device that creates motion. It usually refers to an engine of some kind.
  • Reducer is the component in a pipeline that reduces the pipe size from a larger to a smaller bore (inner diameter).
  • Separator refers to a mechanical device to separate fluids and solids.

Who Uses ANSI/ISA 5.1-2022?

Primary users of this standard are in the chemical, petroleum, power generation, metal refining, pulp and paper, batch, discrete-part processing, and material handling industries. These industries (and others) require the use of control system schematics, functional diagrams, and electrical schematics to describe the relationship to processing equipment and the functionality of measurement and control equipment. Moreover, the application of ANSI/ISA 5.1-2022 can be used in the following work activities that require identification and symbolization:

  • Design Sketches
  • Teaching examples
  • Technical papers, literature and discussions
  • Instrumentation, loop logic, and functional diagrams
  • Function descriptions
  • Conceptual drawings (e.g., Process Flow Diagrams and Utility Flow Diagrams)
  • Construction drawings (e.g., Engineering Flow Diagrams, Mechanical Flow Diagrams, Piping and Instrumentation Diagrams, and Systems Flow Diagrams)
  • Specifications, purchase orders, manifests, and other lists
  • Identification and tag numbering of instruments and control functions
  • Installation, operating and maintenance instructions, drawings, and records

This standard provides information to enable anyone who has a reasonable amount of process and instrumentation knowledge and is reviewing documents depicting measurement and control to understand the means and purpose of the instrumentation shown.

ANSI/ISA 5.1-2022: Instrumentation Symbols and Identification is available on the ANSI Webstore.

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