A2L refrigerant regulation updates: what you need to know today

Preparing for the approval and safe use of A2Ls in commercial refrigeration applications

The move from hydrofluorocarbon (HFC) refrigerants to lower-global warming potential (GWP) alternatives is picking up speed in U.S. HVACR sectors. Many of the new options are classified as “lower flammability” A2L refrigerants.

These refrigerants offer the potential for lower GWP and wide applicability across a spectrum of self-contained and remote commercial refrigeration applications. In addition, recent updates to refrigerant regulations, safety standards and building codes are paving the way for their adoption. But these developments leave many unanswered questions for stakeholders.

I’ve recapped the most important takeaways from my recent blog article on this topic.

What does the A2L refrigerant classification mean?

A2L is a class of refrigerants defined by ASHRAE 34 as having lower toxicity and lower flammability (often referred to as mildly flammable). The ASHRAE 34 standard represents refrigerant safety classifications with an alpha-numeric character shorthand. The first letter is a refrigerant’s toxicity rating, followed by a number to indicate its flammability rating. The third letter in the sequence delineates a subclass of flammable refrigerants that burn very slowly. So A2L is:

A = lower toxicity

2 = lower flammability

L = low burning velocity

How safe are A2L refrigerants?

Industry organizations and regulating bodies have conducted extensive research on the safety of A2L refrigerants in commercial refrigeration systems. To cause a flammable event, three conditions must exist:

1. Equipment must develop a leak.
2. The concentration of leaked refrigerant must exceed the lower flammability limit (LFL) threshold.
3. A flammable source of ignition must be present (e.g., a flame or high-ignition energy source).

LFL is the lower bounds of the concentration level at which a flammable refrigerant could ignite. For a flammable event to occur, the concentration of flammable refrigerant must fall between the LFL and the limit of the higher bounds, or UFL. Risk mitigations are designed to stay below the LFL threshold if a leak happens, so the chance of a flammable event is significantly reduced.

Are A2Ls approved for use in commercial refrigeration?

In 2024, the EPA approved new A2L refrigerant options under its Significant New Alternatives Policy (SNAP) program, SNAP Rule 26. This allows A2Ls to be used in much higher charges than R-290 (i.e., pounds compared to grams), which would make them likely substitutes for legacy HFCs such as R-404A and HFC-134a. Mildly flammable A2L refrigerants are also approved for use in commercial refrigeration in many countries and/or regions around the world.

Which states have updated their building codes to support the safe use of A2Ls?

For the most up-to-date information, please refer to the Air-Conditioning, Heating, and Refrigeration Institute’s (AHRI) A2L refrigerant building code map for your state and local building codes.

How do product safety standards define charge limits and safe use guidelines of A2L refrigerants?

One of the benefits of using A2L refrigerants is the potential for increasing equipment capacities via the use of higher charge limits in self-contained equipment. Per the UL 60335-2-89, 2^nd edition product safety standard, A2L charge limits for self-contained equipment are determined by multiple factors, which include refrigerated unit design and the LFL rating of the selected A2L refrigerant.

Annex CC testing protocols require original equipment manufacturers (OEMs) to design equipment to prevent flammable refrigerant concentrations in the event of a leak and verify that their equipment with more than 150 grams of refrigerant does not exceed 50 percent of the refrigerant’s LFL for an extended period.

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Read the full article for a better understanding of A2L refrigeration, including:

• What an HFO is
• Why A2L refrigerants are gaining in popularity
• How recent updates to safety standards set the stage for wider A2L adoption
• Which refrigerants are non-flammable
• When mildly flammable refrigerants will be used in commercial refrigeration and air conditioning

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Additional resources

• Copeland recently produced an A2L Experts video series, in which Joe Summers, senior product manager for Copeland, and I cover A2L refrigerants, the regulatory landscape and safety standards at length.
• Our E360 content hub features more information about the safe application of A2L refrigerants.
• Learn more about the regulations driving A2L adoption on the Copeland website.