Frames from R-406A Safety Testing video

This page is a supplement to the paper Some Safety Studies of a Ternary Refrigerant. R-406A has been safety classified by ASHRAE as "A1/A2". This means (as formulated / worst case), and for R-406A, is "lower toxicity group, non flammable" as formulated / "lower toxicity group, lower flammability group" after worst case leakage.

You will see HCFC refrigerants being "vented" here for R&D purposes. Craig Haas of the US EPA Enforcement Division has clarified that R&D purposes (such as safety testing) do not fall under the venting prohibitions of the Clean Air Act, Sections 608 & 609.

The 2nd character of the classification is the flammability classification (1 = non flammable, 2 = lower flammability group, 3 = higher flammability group). As formulated, R-406A is totally non flammable, neither vapor nor liquid will burn. If leakage occurs (from a vapor region), the composition will change. At somewhere between 40-50% and 90-100% of total leakage (mass loss), the remaining charge may become WEAKLY FLAMMABLE.

The point at which the weak flammability zone is entered depends primarily on the temperature during the leaking process. Cooler temperatures will cause the zone to be entered earlier, and warmer temperatures will cause the zone to occur later or not at all. Cooler leakout (fractionation) temperatures only cause the zone to be entered earlier, they do not appear to increase the severity of the flammability (it always stays "weak"). In anycase, the end product of a worst case leakdown is R-142b. The R-600a (isobutane) is gone before the end is reached, and is inhibited by remaining R-22. This chart is vapor composition by volume (headspace above the liquid), not liquid composition by weight. That is why the R-22 starts out at 70% instead of 55% as given in the formulation. (leakout at 68F)


Click on each of the images to see a larger, more detailed version. These images all came from video. The first example (left) is virgin (as formulated) R-406A, vapor, blowing through a propane torch flame. Nothing happens. On the right, is R-406A "liquid" venting from a cylinder into a propane torch flame. Nothing happens. Now and then a small "sparkle" occurs from decomposition of the refrigrant in the flame.


Left, R-406A liquid spill on the ground, boiling vigorously. As the torch flame is brought into the area above the spill, some decomposition (small yellow flame area) occurs (does not spread or continue without the torch being present), and the torch is extinguished. Right, a special (weakly flammable) cylinder is made up of what R-406A turns into after it has vapor leaked out about 95% (at 70F), to simulate worst possible conditions. This composition is (% wt) 3/84/13 R-600a/R-142b/R-22. Vapor, liquid, and liquid spill tests are done on this "worst case mixture".


Left, a propane torch is placed in a stream of worst case composition R-406A vapor venting. A small amount of flame is seen near the torch only. It does not propagate nor burn on its own with the torch removed. Right, a propane torch is placed in a stream of worst case composition R-406A liquid venting. A small amount of flame is seen near the torch only. It does not propagate or burn on its own with the torch removed. Now and then a small "puff" of flame will form, and extinguish itself. Neither venting jets of R-406A worst case composition vapor nor liquid will ignite and stay lit. Pure R-142b (at 100% leakout) exhibits similar behavior. There is no "flash point".


Left, liquid Spill of R-406A after (worst case) leakdown (8 fluid oz in a beaker), can be ignited with a propane torch, and will stay lit for about 2 seconds, and self extinguish. Flame stays in the beaker for the most part. Pure R-142b exhibits similar behavior. Right, liquid spill of R-406A after (worst case) leakdown (8 fluid oz in a beaker dumped onto the ground - boiling vigorously), can be ignited with a propane torch, and will stay lit for about 2 seconds, and self extinguish. Pure R-142b exhibits similar behavior.



R-290 (propane) vapor and liquid spill tests
FOR COMPARISON ONLY. To demonstrate class 3 flammability


Left, pure propane (R-406A never does anything like this) vapor being vented, ignites and easily sustains with ignition source removed (same propane torch). Right, propane, 8 fluid oz, liquid spill on ground. Easily ignited and sustains with ignition source removed. Fire totally engulfs the area. If spilled first, and later ignited, an explosion is likely. Many competitors describe R-406A as this case, which simply is not true. The difference between weak "class 2" flammability and "class 3" is easily seen. The small "dark" area, near the center at the "bottom" of the fire is the beaker. This pix was taken about 50 feet away for obvious reasons.