ISA 5.5 : 1985

1 Purpose
2 Scope
  2.1 Application to work activities
  2.2 Relationship to other ISA Standards
  2.3 Relationship to other symbol standards
  2.4 Definitions
3 Symbols
  3.1 Symbol usage
  3.2 Grouping of symbols
  3.3 Structure of Symbols
Appendix A - Examples of use
Appendix B - Primary measurements recommended usage

ISA-5.5-1985, Graphic Symbols for Process Displays, is a comprehensive guide to establishing a uniform system of graphic symbols used in process monitoring and control across various industries, including chemical, petroleum and power generation. This standard aims to enhance operator comprehension and reduce errors by providing easily recognizable symbols that facilitate effective communication between operators and control systems. By integrating these symbols into visual display units (VDUs), users can quickly interpret critical information related to processes and equipment. This standard categorizes graphic symbols into 13 major groups, covering components such as connectors, containers, valves and actuators. Each symbol is designed with specific attributes, including color usage, orientation and blinking effects, to convey operational status clearly. This document emphasizes the importance of maintaining aspect ratios and spatial relationships among symbols to ensure clarity and consistency in representation. Additionally, ISA-5.5 encourages the use of color coding to improve information perception and provides guidance on compatible color combinations for optimal visibility.ISA-5.5 supplements existing ISA standards and aligns with other industry symbol standards, promoting compatibility and coherence in documentation and displays. It serves as a foundational reference for manufacturers and users, ensuring that graphic symbols are effectively utilized in modern control systems. By focusing on reducing operator training time and enhancing communication, ISA-5.5-1985 plays a crucial role in improving safety and efficiency in process operations.For professionals involved in instrumentation and control systems, adopting ISA-5.5-1985 means leveraging a well-defined set of symbols that streamline the design and interpretation of process displays. This ultimately leads to better decision-making and operational performance, making it an essential resource for anyone looking to optimize their process visualization strategies.

The standard is suitable for use in the chemical, petroleum, power generation, air conditioning, metal refining, and numerous other industries.