In the constantly evolving world of refrigerant options, the HVACR industry is preparing for the inclusion of mildly flammable or flammable refrigerants in an increasing number of applications. But the expanded use of these refrigerants won’t happen overnight, as there is a multistep approval process they must undergo to be approved for new applications.

Refrigerants are classified by ASHRAE as A1 (nonflammable), A2L (mildly flammable), B2L (toxic, mildly flammable), and A3 (flammable). The main allure of using A2L, B2L, or A3 refrigerants in place of A1 refrigerants lies in their reduced global warming potential (GWP).

At a recent joint Air-Conditioning, Heating, and Refrigeration Institute (AHRI), ASHRAE, China Refrigeration and Air-conditioning Association (CRAA) technology forum that took place during the 2015 AHR Expo, Xudong Wang, director of research, AHRI, explained the increased use of flammable refrigerants in the U.S. would require four major steps:

• U.S. Environmental Protection Agency (EPA) Significant New Alternatives Policy (SNAP) approval;

• Changes to ASHRAE Standard 15-2013 (packaged w/ 34-2013), “Safety Standard for Refrigeration Systems and Designation and Classification of Refrigerants;”

• Adoption by model building codes and state and local codes;

• Compliance with safety standards for equipment that would use the refrigerants.

Last summer, the EPA, under its SNAP program, proposed to add ethane, isobutene, propane, R-441A, and R-32 to the approved refrigerants list subject to use conditions because of flammability.

According to Wang, the EPA SNAP proposal is one of the essential steps in the approval process for flammable refrigerants. Another essential step is changes to ASHRAE Standard 15.

“ASHRAE Standard 15 is based on three classifications: what refrigerant is being used, the occupancy type of the building involved, and the type of refrigerating or air conditioning system being used,” Wang explained. “Based on this information, the standard then goes on to establish appropriate restrictions and requirements to ensure safeguards for life, limb, health, and property for the duration of the life of the building.

“Requirements include how refrigerants are used, where the refrigerant can be located, what quantity of refrigerant is allowed, how the equipment is designed and built [whether in a factory or on the job site], to what standards for electrical safety and pressure safety the equipment was built, and how the equipment is operated and tested,” he added. “All these requirements must be defined in some shape or form for all the possible combinations of the three classifications.”

ASHRAE Standard 15 generally allows the use of refrigerants classified as A2 for human comfort in self-contained systems containing less than 3 kg (residential) or 10 kg (commercial), depending on location in the building, he added. Split systems are generally not allowed to contain flammable refrigerants because of their field-installed refrigerant tubing/piping.

Wang explained that Standard 15 is on continuous maintenance, which means a standing committee is established and charged with updating the document on a continuous basis. Change proposals can come to the standing standard project committee from anyone inside or outside the industry. The committee then reviews the proposed changes, decides whether the concept is valid or not, questions if the language needs any tweaking, and then votes to accept or reject. As part of the American National Standards Institute (ANSI) standards development process, the committee members represent a balance of viewpoints, and all proposed changes are then further vetted through a public-review process intended to reach consensus in the final language.

After public review, comments are addressed (sometimes after multiple public review periods) and an addendum to the standard is published. On a three-year cycle, ASHRAE then combines all published addenda since the last edition and publishes a new edition. The next such edition for Standard 15 is expected to be released in 2016.

In addition, to be in compliance with ASHRAE Standard 15, products using flammable refrigerants must also be certified and listed by relevant equipment safety standards, such as UL standards. These standards specify the requirements on how to construct the equipment to ensure it is safe to use. For example, the current edition of UL/CSA/ANCE 60335-2-40, “Safety of Household and Similar Electrical Appliances, Part 2-40: Particular Requirements for Electrical Heat Pumps, Air-Conditioners and Dehumidifiers,” does not address the use of flammable refrigerants. It essentially disallows the use of all flammable refrigerants in its covered products. New requirements will have to be established in its future edition to allow the certification and listing by UL of equipment using flammable refrigerants.

After model building codes’ adoption/harmonization of the new ASHRAE Standard 15, adoption by state and local codes would be the final step. “After that, the refrigerants could be used in the field,” Wang said.

He added, however, model building codes are published once every three years, following a fixed process during each code change cycle.

“As safety requirements for class 2L refrigerants were not added to the 2015 building codes, the next opportunity is the 2018 edition,” Wang said. “In addition, the adoption and effective dates of new model building codes by individual states or localities will all be different.”