ANSI/IIAR 2-2021 American National Standard for Design of Safe Closed-Circuit Ammonia Refrigeration Systems

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 ANSI/IIAR 2-2021 is a standard for the design of safe closed-circuit ammonia refrigeration systems.  It incorporates topics traditionally addressed in other codes and standards making it the single most comprehensive standard covering the safe design of closed-circuit ammonia refrigeration systems published to date. 

This standard was first issued in March of 1974 by IIAR as IIAR 74-2. The standard was first approved as an American National Standard by the American National Standards Institute (ANSI) in March 1978 as ANSI/IIAR 74-2-1978. A revision of the standard, ANSI/IIAR 2-1984 was approved by ANSI in July 1985, as were subsequent revisions in December 1992, August 1999, June 2008, August 2010, and December 2012. ANSI/IIAR 2-2014 was approved by ANSI in September 2015 and was published in November 2015. ANSI IIAR 2-2014, Addendum A, was approved by ANSI in June 2019 and published in July 2019. This edition of ANSI/ IIAR 2 was approved by ANSI in July 2021 and published in August 2021.

IIAR Standards contain both normative and informative information, establishing both the minimum requirements for industry compliance and advisory information where applicable.  IIAR Standards are ANSI approved as they are subject to a rigorous public review and reaffirmation process every 5 years to ensure that they represent an industry consensus.

Some of the changes to this edition include: 

Clarification that existing facilities comply with IIAR 9; New definitions have been added; Requirements for eyewash/safety showers have been re-organized and clarified; Ammonia detection requirements have been changed; Changes to machinery room exhaust and ventilation have been updated based on new requirements; New requirements for Evaporators are included concerning design for freeze protection and design for frozen products; Inclusion of emergency pressure control systems where required by AHJs; New appendices include O. (Informative) Designing to Avoid Component Failure Caused by Abnormal Pressure or Shock, P.(Informative) Removal of Water from a Refrigeration System , and Q. (Informative) Guidelines for the Identification of Ammonia Refrigeration Piping and System Components.

Table of Contents:
Part 1 General
Chapter 1. Purpose Scope, and Applicability
Chapter 2. Definitions
Chapter 3. Reference Standards

Part 2 Design and Installation Considerations Affecting Construction
Chapter 4. Location of Ammonia Refrigeration Equipment
Chapter 5. General System Design Requirements
Chapter 6. Machinery Rooms
Chapter 7. Refrigeration Equipment Located in Areas Other than Machinery Rooms

Part 3 Equipment
Chapter 8. Compressors
Chapter 9. Refrigerant Pumps
Chapter 10. Condensers
Chapter 11. Evaporators
Chapter 12. Pressure Vessels
Chapter 13. Piping and Hoses
Chapter 14. Packaged Systems and Equipment
Chapter 15. Overpressure Protection
Chapter 16. Instrumentation and Controls
Chapter 17. Ammonia Detection and Alarms
Chapter 18. Absorption Systems

Part 4  Appendices
Appendix A. (Informative) Explanatory Material
Appendix B. (Informative) Ammonia Characteristics and Properties
Appendix C. (Informative) Methods for Calculating Relief Valve Capacity for Heat Exchanger Internal Loads
Appendix D. (Informative) Duplicate Nameplates on Pressure Vessels
Appendix E. (Informative) Method for Calculating Discharge Capacity of a Positive
Displacement Compressor Pressure Relief Device
Appendix F. (Informative) Pipe Hanger Spacing, Hanger Rod Sizing, and Loading
Appendix G. (Informative) Hydrostatic and Liquid Overpressure Relief
Appendix H. (Informative) Stress Corrosion Cracking
Appendix I. (Informative) Emergency Pressure Control Systems
Appendix J. (Informative) Machinery Room Signs
Appendix K. (Informative) Alternative Ventilation Calculation Methods
Appendix L. (Informative) Pipe, Fittings, Flanges, and Bolting
Appendix M. (Informative) Operational Containment
Appendix N. (Informative) Ammonia Absorption Refrigeration
Appendix O. (Informative) Designing to Avoid Component Failure Caused by Abnormal Pressure or Shock
Appendix P. (Informative) Removal of Water from a Refrigeration System
Appendix Q. (Informative) Guidelines for the Identification of Ammonia Refrigeration Piping and System Components
Appendix R. (Informative) References and Sources of References