The shift to A2L refrigerants created confusion about more than just new equipment specs. Cylinder standards changed, too, and not everyone got the memo. During ACCA Strategic Partner Arkema’s recent webinar, “Where Did All the Colors Go? Setting the Record Straight on A2L Cylinders,” Kris Crosby and John Maiorana explained what’s changed, why it matters, and what to watch for when buying refrigerant.
ACCA members can watch the full webinar recording here.
Key Highlights
- A2L cylinders legally require pressure relief valves that can reset, not the cheaper rupture discs that vent entire contents. Non-compliant cylinders with rupture discs are appearing in the U.S. market from overseas manufacturers.
- The industry switched to gray cylinders with red bands because we literally ran out of colors as refrigerant options expanded beyond the original three (R-12, R-502, R-22).
- Cylinder fill weights dropped from 30 pounds to 20 pounds because DOT regulations tie fill capacity to refrigerant density, and A2Ls have different densities than older refrigerants.
What changed with A2L cylinders
Krosby outlined three critical differences between A1 cylinders (used for R-410A) and A2L cylinders (used for R-32 and R-454B):
- Pressure relief device: A2L cylinders use resettable valves instead of rupture discs. When pressure builds, the valve opens to release refrigerant until pressure drops to safe levels, then closes. This keeps the remaining refrigerant in the cylinder instead of venting everything into your service van.
- Red band: A2L cylinders must have a red band around the top to denote mild flammability. This is a legal requirement.
- Left-hand threads: Most manufacturers switched to left-hand threads (CGA 164 fitting) to give technicians a tactile reminder they’re working with something different. This is an AHRI guideline, not legally required, but widely adopted. Adapters are available at most HVACR wholesalers.
The non-compliant cylinder problem
Krosby addressed a concerning trend: A2L cylinders appearing in the field with rupture discs instead of the required pressure relief valves. These cylinders, primarily manufactured in China, India, or the UAE, use cheaper rupture discs to cut costs but create serious safety issues.
If a cylinder with a rupture disc over-pressurizes, the entire contents vent into whatever space the cylinder occupies. With mildly flammable refrigerants, that’s dangerous.
How to avoid buying the wrong cylinders
Look for three things:
- Pressure relief valve (not a rupture disc)
- Red band around the top
- Flammable placard on the box
Stick with reputable suppliers and avoid online marketplaces or social media sales, especially during product shortages. If you see non-compliant cylinders, contact your dealer or the manufacturer. Crosby emphasized that if a company cuts corners on cylinder safety, question the quality of their refrigerant, too.
Why cylinder weights keep dropping
DOT regulations calculate maximum fill weight based on refrigerant liquid density multiplied by internal cylinder volume. As refrigerant density changes, allowable fill weight changes. Manufacturers want to put the maximum legal amount in every cylinder, but if R32’s density only allows 24 pounds in a cylinder that held 30 pounds of R-22, they often choose a round number like 20 pounds to maintain manufacturing tolerances.
Maiorana added that A2L cylinders also need adequate vapor space around the pressure relief valve to prevent liquid contact, which can cause valve leakage.
Storage and what’s coming in 2028
Store A2L cylinders with the pressure relief valve in the vapor space (pointing up), whether vertical or horizontal. The maximum temperature remains 125°F for all refrigerant cylinders. Placard requirements for service vans haven’t changed with A2Ls.
Starting in 2028, the refrigerant heel (remaining material) in disposable HFC cylinders must be recovered before disposal. Technicians can either recover the heel in the field and maintain certification records or send cylinders with heels to certified manufacturers or reclaimers.
Why gray cylinders
The industry ran out of colors as refrigerant options multiplied beyond the original three. Gray with the actual ASHRAE R-number provides clarity without needing dozens of distinct colors. For A2Ls, add the required red band. Larger returnable cylinders are following the same path as they come back for their required five-year hydrostatic testing.
As A2L adoption continues, contractors who know what to look for in compliant cylinders will avoid the safety risks and quality questions that come with cutting corners on equipment.
ACCA members can access the full webinar recording here.
Arkema is an ACCA Strategic Partner. To learn more about our Strategic Partner Program, contact partners@acca.org or visit acca.org/partners.
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