The International Society of Automation (ISA) is the home of many standards related to process safety, instrumentation, control, networking and security, automation and business systems — including ISA-5, a series of standards that includes aspects foundational to the automation profession.
What Is ISA-5?
The ISA-5 standards establish the means for documenting and illustrating the uses and functions of measurement and control instruments and systems. When integrated into a system, the designations and symbols presented in the ISA-5 series offer a simplified way to convey complex information among trained and knowledgeable automation professionals. These standards are widely adopted around the world in a variety of industries.
Uniform and clear documentation is crucial in the design, implementation and maintenance of instrumentation and control systems. The ISA-5 standards set guidelines for such documentation.
Comprehensive List of ISA-5 Standards and Technical Reports
ANSI/ISA-5.1-2024, Instrumentation and Control Symbols and Identification
ANSI/ISA-5.1, also known as ISA-5.1, is the oldest and most widely used standard published by ISA. ANSI/ISA-5.1-2024, Instrumentation and Control Symbols and Identification, provides a standardized system for depicting and identifying instruments, devices and their functions within instrumentation and control systems. The goal is to ensure these elements are represented uniformly and clearly. This standard establishes consistent symbols and identification methods — facilitating better communication and understanding among professionals involved in the design, installation, operations and maintenance of instrumentation and control systems.
Originally published in 1949, ISA-5.1 continues to play an essential role for automation professionals in the global process industries. It helps improve the accuracy and efficiency of documentation and communication across a wide range of industries that rely on instrumentation and control systems. The most recent version, ANSI/ISA-5.1-2024, includes an update to the title to emphasize that symbols for control are included as well as improvements to readability. The ISA5 standards committee — the body that updated the standard — also added new symbols, recognized new automation technology, added new reference sections and added a loop instrument diagrams symbol table.
Add PDF to Cart Add Print to CartISA-TR5.1.02-2024, Instrumentation and Control Identification System Guidelines
This technical report was created as a supplement to ISA-5.1. It offers additional guidance, rationale and examples in general terms for those identifying and implementing instrumentation and control equipment and its functions.
Add PDF to Cart Add Print to CartISA-TR5.1.03-2024, Instrumentation and Control Graphic Symbol Guidelines
This technical report provides more guidance in general terms on how to apply the symbols for instrumentation and control equipment drawings and systems found in ISA-5.1.
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ISA-5.4-1991, Instrument Loop Diagrams
ISA-5.4-1991, Instrument Loop Diagrams, establishes guidelines for creating and using instrument loop diagrams through the various stages of instrumentation systems, from design and construction to start-up, operation, maintenance and modification.
Instrument loop diagrams serve multiple purposes, including the depiction of control philosophy, instrument hardware specification, aid in construction and installation and the facilitation of troubleshooting and maintenance. This standard outlines the minimum content requirements for loop diagrams, including identification of loop components, interconnections, energy sources and control actions. ISA-5.4 emphasizes consistency in format and the use of standardized symbols as found in ISA-5.1.
ISA-5.4 aims to help users in the process industries — including chemical, petroleum and power generation — understand and improve communication through instrument loop diagrams. These diagrams consolidate information that would otherwise be spread across multiple documents, helping to reduce engineering costs, improve loop integrity and facilitate maintenance troubleshooting.
Add PDF to Cart Add Print to CartISA-5.5-1985, Graphic Symbols for Process Displays
The purpose of the ISA-5.5 standard is to establish a system of graphic symbols for process displays that plant operators, engineers and other professionals use for process monitoring and control. The system established in this standard facilitates quick understanding of the information conveyed through displays and helps to create uniformity of practice throughout the process industries.
For guidance related to human-machine interfaces (HMIs) of process automation systems, refer to ANSI/ISA-101.01 and its technical reports.
Add PDF to Cart Add Print to CartISA-5.06.01-2007, Functional Requirements Documentation for Control Software Applications
This standard defines functional requirements specifications for control software documentation in real-time batch, discrete and continuous process automation systems. It covers the classes of industrial automation equipment and systems consisting of distributed control systems, programmable controllers and industrial personal computers — encompassing both digital and analog control devices in addition to non-control actions (for example, operator messages and batch end reports).
ISA-5.06.01-2007, Functional Requirements Documentation for Control Software Applications, is intended to provide techniques for documenting control system software, using a set of terms that relate directly to the languages commonly used by plant operators. This standard also offers a basis for validation of run-time application software after it is developed and tested to ensure that the initial requirement specification has been met.
Add PDF to Cart Add Print to CartISA-TR5.1.01/ISA-TR77.40.01-2012 (R2016), Functional Diagram Usage
This technical report expands upon — and illustrates — usage of function block symbols and functions and prepares examples in development of complex function block symbols and functions. The goal is to provide advice and guidance in documenting application software through functional diagrams.
Add PDF to Cart Add Print to CartISA-TR5.9-2023, Proportional-Integral-Derivative (PID) Algorithms and Performance
This technical report documents common proportional-integral-derivative (PID) algorithms used in industrial control systems, including the various algorithms’ implementation methods, options and performance measurements.
Even though PID controllers have been used for more than a century, a standard describing fundamentals, terminology, best practices and special functions does not exist. This document is intended to lay the foundation for such a standard.
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Add PDF to Cart Add Print to CartBeyond ISA-5: A Note on the ISA-20 Standard
Parallel to the ISA-5 standard series, automation professionals looking for guidance around instrumentation symbols and documentation may also choose to seek out the ISA-20 standard. ISA-20 provides standardized specification forms for instruments, primary elements and control valves. ISA-TR20.00.01-2007 includes the original forms developed in 1981 in addition to dozens of other specification forms developed over the years. These forms are intended to aid in the design, purchase and manufacture of process measurement and control instrumentation.
Specific Questions on ISA-5?
We welcome dialog on the ISA-5 series of standards. For more information, please contact us at standards@isa.org. If you are an ISA member, you can also view a list of standards committee members.