Flammable Refrigerant Update
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The AIM Act mandates the phasedown of high-GWP HFCs federally (state regulations may vary a little bit, but all of them will have an HFC phasedown); in the end, production will be decreased by 85%, meaning that there is not a total refrigerant phaseout. Recovery and reclamation will be crucial.
R-32, an A2L refrigerant, has been used in window and package units, and R-1234yf has also been used industrially and in automobiles. Most A2Ls going to market will include those refrigerants and refrigerant blends. Installation and design standards will be tailored to the A2L refrigerants. A2Ls are nowhere near flammable as A3s, including propane.
ASHRAE Standard 34 establishes a lettering and numbering system based on toxicity (A or B) and flammability (1, 2L, 2, and 3). Non-toxic refrigerants have the letter A, and toxic ones have the letter B. Non-flammable refrigerants under test conditions receive the number 1, mildly flammable receive 2L, moderately flammable receive 2, and highly flammable refrigerants receive 3.
We have largely been working with A1 refrigerants, like R-22 and R-410A. A2Ls are non-toxic but propagate a small flame under test conditions; A2Ls are significantly less flammable than A3s, like hydrocarbons, which is evident in Dr. Chuck’s flask test. Flammability also depends on properties like the minimum ignition energy, the heat of combustion, and the burning velocity. A2Ls take a lot more energy to ignite than A3s, and their heat of combustion and burning velocity values are quite low by comparison. The industry is moving to A2Ls to minimize risk (as opposed to A3s). Systems for A3 refrigerants typically have smaller charges than other systems with lower flammability to minimize risk.
We will start seeing new tanks with special safety features, including ones with spring-loaded pressure relief valves that can open and close automatically if the pressure gets too high. You’ll likely see left-handed threads on some tanks, and adapters may become available for them. Recovery tanks will also have a red stripe, and you can decommission tanks by puncturing them (not with a ruptured disc). Refrigerant tanks will come in neutral colors and have shrink wrap to prevent counterfeit refrigerant from entering circulation, and the refrigerant name will be labeled on the tank.
Some of the best (albeit not required) practices for A1s will be required for A2Ls. These include purging the system with nitrogen, evacuation, and leak/pressure testing. Otherwise, the refrigerants have very similar pressures to R-410A, and working on systems with A2L systems will be similar to working on R-410A systems.