Knowledge/Refrigerants/A1, A2L, A2 and A3: what the classes actually mean
A1, A2L, A2 and A3: what the classes actually mean
The letter is toxicity and the number is flammability. A means low toxicity, an exposure limit of 400 ppm or more. Class 1 won't spread a flame at 60°C. Class 2L burns slowly. It needs at least 3.5% of the air by volume to catch (its lower flammability limit, or LFL) and burns under 10 cm/s. Class 3 catches easily.
- A or B
- 400 ppmexposure limit: A at or above, B below
- Class 1
- No flame spreadat 60°C and 101.3 kPa
- Class 2L
- LFL 3.5% or moreand burns slower than 10 cm/s
- Class 3
- LFL under 3.5%catches easily
What's the test for each class?
| Class | The test | Examples |
|---|---|---|
| 1 | Does not exhibit flame propagation when tested in air at 60°C and 101.3 kPa | R22, R134a, R404A, R410A, R744 |
| 2L | Flame propagation at 60°C, LFL at or above 3.5% by volume, heat of combustion below 19,000 kJ/kg, and maximum burning velocity below 10 cm/s at 23°C | R32, R1234yf, R1234ze, R717 |
| 2 | As 2L but without the burning velocity cap | R152a, R439A |
| 3 | Flame propagation, LFL below 3.5% by volume, heat of combustion at or above 19,000 kJ/kg | R290, R600, R601, R1270 |
2L is really a slower-burning version of 2. The only extra requirement is the cap on burning velocity. That one line is the whole difference between the class most new air conditioners use and a class that would be far harder to work with.
What does each class mean on the job?
- A1 means it won't spread a flame, and your standard tools are fine
- A2L means it will burn, but slowly. It needs A2L-rated tools, leak detection, room area rules and a minimum floor area declared by the manufacturer
- A3 means readily flammable, like LPG (bottled gas). Charges sit roughly in the 150 g to 1 kg range, and it isn't covered by ARCtick licensing (the Australian Refrigeration Council licence) at all
That last point surprises people. A3 refrigerants aren't covered by ARCtick licensing. That doesn't make them any safer. It just means the licence doesn't reach them, and it matters if you work on propane hot water heat pumps.
What about blends with two classes?
Some blends carry two classes, like A1/A2. As a blend separates (fractionates), say through a leak, what's left can be more flammable or more toxic. The first class is the blend as made. The second is the worst case after it separates.
Why are propane charges so much smaller than R32?
| Refrigerant | LFL (kg/m³) | Burning velocity | Autoignition |
|---|---|---|---|
| R32 | 0.306 to 0.307 | 6.7 cm/s | 648°C |
| R454B | 0.297 | 5.2 cm/s | not determined |
| R454C | 0.293 | 1.6 cm/s | 444°C |
| R1234yf | 0.289 | 1.5 cm/s | 405°C |
| R1234ze(E) | 0.303 | 0 | 368°C |
| R290 | 0.038 | about 46 cm/s | about 470°C |
R290 catches fire at roughly an eighth of the concentration R32 needs. That one ratio explains why they're treated so differently. You only need an eighth as much propane in the air to get a flammable mix.
That's why A3 charges are capped in the hundreds of grams while A2L charges run to several kilos in the same room. On the job, the figure you're held to is the minimum floor area in the manufacturer's manual. The figures below are our own sums from the LFL values, marked computed, not a published Australian table.
With a charge under 6 times its LFL, an A2L system has no room-size rule at all. That's 1.836 kg for R32 and 1.782 kg for R454B. The R454B figure takes it as A2L, which is how it's commonly classed, but we couldn't confirm that class from an Australian primary source. For A2 and A3 the multiplier is 4 times LFL, which for R290 is 0.152 kg using the rounded 0.038 figure. That's where the well-known 150 gram figure comes from.
None of these is an Australian legal limit. The Australian standard is paywalled and we couldn't read its numbers, so treat them as a guide to what the manual is telling you.
Working out what the transition means for you?
There's a lot of noise about what's banned and when, and most of it is either early or wrong. What matters is what you buy and stock this year.
Kevin will give you the straight version.
Who this is for: small and medium HVAC contractors in Victoria. If you're a homeowner after a rebate or a repair, you need a licensed contractor, not us, and yours can point you the right way.
Related
- Why topping up a leaking system isn't legal hereFind a leak and all the refrigerant has to come out before the repair. That's the code for every refrigerant, blend or pure. No exceptions.
- Prohibited charging, and why you can't go up in GWPSince January 2020 you can't charge equipment with a gas of higher GWP than the one it was designed for. It applies whether or not you hold a permit.
- Refrigerant recovery, and the tools A2L won't shareEvery recovery rule in one place, the equipment standards behind them, and why your A1 recovery kit generally isn't fit for A2L gas.
- Identify refrigerant by the label, never by the colourAustralia doesn't use the American whole-body colour system. Cylinders are white or galvanised with a coloured band, and four common gases aren't charted.
Review date: 1 April 2027. Figures in this area change without much notice and this page carries some that will go stale. Every number above is dated and sourced so you can check it yourself. If you find something out of date here, tell us and we will fix it.