Refrigeration consultants Star Technical Solutions advise on the implications that the new and improved version of the International Institute of Ammonia Refrigeration (IIAR) standard on the safe design of closed-circuit ammonia refrigeration systems will have on refrigeration dependent businesses.

The new American National Standard for the safe design of closed-circuit ammonia refrigeration systems, ANSI/IIAR 2-2014, sets the minimum requirements for industry compliance and adherence to American codes and regulations and is “significantly different to previous versions,” says Star Technical Solutions Director, David Blackhurst.

Also a voting member of the IIAR Board of Directors, Mr Blackhurst adds: “This is an essential guide for the safe design and operation of ammonia refrigeration systems. It is the regulatory document of ammonia refrigeration and collates best practice information in industrial ammonia refrigeration from practitioners across the world.”

“It is, at the very least, the most comprehensive publication on ammonia refrigeration design safety available today.”

The key changes to the new edition are the incorporation of topics traditionally addressed in other codes and standards, which makes it the first single comprehensive standard covering safe design of closed-circuit ammonia refrigeration systems. The IIAR2 includes ASHRAE Standard 15 – Safety Standard for Refrigeration Systems, the Uniform Mechanical Code, the NFPA 1 Fire Code, the International Mechanical Code and the International Fire Code.

The new standard covers a wider range of information on stationary closed-circuit ammonia refrigeration systems. The new additions include design and installation considerations affecting construction; standalone sections for each type of component such as compressors, refrigerant pumps, condensers, evaporators, pressure vessels and piping; instrumentation and controls for automated systems; and ammonia detection and alarm systems.

A few of the changes that have been added to the new document are:

– A whole new chapter on the use of Ammonia Refrigeration Machinery. This comprises restrictions on the use of ammonia refrigeration systems based on the occupancy classification of the area where the system or equipment will be located. 

– The System Design chapter specifies the requirements that apply to selecting system design pressures. For example, the minimum low-side pressure is 250 psig; the minimum high-side design pressure for water-cooled and evaporatively-cooled systems is 250 psig; the minimum high-side design pressure for air-cooled systems is 300 psig. However, individual pieces of equipment might require higher design pressures. Requirements for the removal of oil from oil pots have been changed such that there is no longer a requirement to temporarily install a rigid-piped connection. Direction for the provision of maintenance and functional testing was added, as well as minimum valve tagging standards for system emergency shut-down procedures.

– ‘Refrigeration Equipment Located in Areas Other than Machinery Rooms’ is also new material. Previously, regulations concerning certain types of refrigeration equipment located in areas other than machinery rooms have not been provided. For example, in industrial occupancies, it is often necessary to have evaporators located outside of a machinery room in storage and production areas. This chapter provides minimum safety requirements for locating refrigeration equipment in areas other than machinery rooms.

– The section on Compressors includes a notable change specifying a 3/4-inch minimum size for relief connections.

– The chapter on Refrigerant Pumps provides requirements for refrigerant pumps, which are different from those that are specified for compressors.

– The Condensers section continues to provide requirements for air-cooled condensers and air-cooled de-superheaters, and evaporative, shell-and-tube, plate heat exchanger and double-pipe condensers.

– New sections on scraped (swept) surface heat exchangers and jacketed tanks have been added to the Evaporators chapter.

– ‘Pressure Vessels’ provides minimum design pressure requirements that are consistent with those described above. In addition, like Chapter 8, the chapter establishes that the minimum size for a relief connection is 3/4-inch for vessels that are over 6 inches in diameter and 1 inch for vessels that are 10 cubic feet or larger.

– ‘Ammonia Detection and Alarms’ establishes the requirements for detection and system response functions. This chapter standardizes requirements that have historically varied depending on jurisdiction, designer, contractor, supplier and end-user interpretations.

In addition, the standard also contains advisory and practical information from international accepted industry practices.

The American National Standards Institute (ANSI) oversaw the development of the IIAR 2 standard following a series of public reviews and stringent controls set up to ensure the representation of the refrigeration industry consensus.

Blackhurst said, “We are very pleased with the amount of support shown during the public reviews conducted in the drafting of the IIAR 2 standard revision. Although the process has been lengthy and exhaustive due to the amount of comments from respondents, it clearly demonstrates the industry’s commitment to ensuring the safety and reliability of the industrial refrigeration operation environment.”

The IIAR is the world’s leading advocate for the safe, reliable and efficient use of ammonia and other natural refrigerants and has broad industry experience representation including manufacturers, design engineers, contractors, end users, academics, scientists and trainers.

The IIAR Standards set the standard for the refrigeration industry and are a must-have technical resource to ensure a safe and efficient industrial refrigeration operating environment. To receive a copy of the ANSI/IIAR 2 Standard, go to  

Free copies of the standard will be provided to those attending the in depth training session on the standard at the IIAR conference, which will take place on Sunday 20th March in Orlando, FL. For more information, visit

Star Technical Solutions advises ammonia refrigeration end-users to keep the new IIAR 2 Standard handy