• ISA5.1, Instrumentation Symbols and Identification

    ISA5.1 Scope

    The standard is suitable for use whenever any reference to an instrument is required in the chemical, petroleum, power generation, air conditioning, metal refining, and numerous other industries.

    The standard is intended to provide sufficient information to enable anyone reading a flow diagram and having a reasonable amount of plant knowledge to understand the means of measurement and control of the process without having to go into the details of the instrumentation that require the knowledge of an instrument specialist.

    ISA5.1 Purpose

    The purpose of this standard is to establish a uniform means of designating instruments and instrumentation systems used for measurement and control. To this end, a designation system is presented that includes symbols and an identification code.

    The differing established procedural needs of various organizations are recognized, where not inconsistent with the objectives of the standard, by providing alternative symbolism methods. A number of options are provided for adding information or simplifying the symbolism, if desired.


    The ISA5.1 subcommittee recently revised and published the updated ANSI/ISA-5.1-2009Instrumentation Symbols and Identification.

    For more information about ISA5.1, contact Charley Robinson, ISA Standards.


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    Grover Allen

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