What does A2L mean for R32 refrigerant?

Looking at the environmental impact & regulations it seems that most Japanese manufacturers have confirmed pre-2017 launches for RAC products using R32 refrigerant; which has a mildly flammable property.

The mild flammability is only an issue if you do not understand why and how. The products have a flammable logo on the nameplate so awareness and management are key to this.

R32 has a GWP of 675 compared to R410A which has a GWP of 2088. This means that our refrigerant suppliers can continue to supply our specific industry with refrigerant for the next few years.

What we as an industry need to do is focus more on containment and promote good practice. Keeping refrigerant where it should be is the ultimate goal.

What is here to stay is A2L, all of which are mildly-flammable refrigerants. This is a culture change that we need to get to grips with now.

What does it mean by  A2L Refrigerants. They are flammable. Or, to be exact, they are “mildly flammable”.

Some installer have mentioned “it is not really flammable and that this is much ado about nothing”. Let’s explore that and examine the facts and the reality.

In the last twenty years the world has changed. A naked flame applied to R22 with mineral oil would create a similar effect to R32 with synthetic oil. Mineral oil such as Suniso 3GS used with CFC or HCFC refrigerants is a “product not classified as flammable but is inherently combustible”

But that was then and this is now. We live in a world dominated by health and safety, legislation and regulation. Unless you are extremely fortunate you will have clients who will expect you to be aware that A2L refrigerants are flammable (albeit mildly) and that you have training, documentation and procedures to handle this fact.

During the 80’s & 90’s we have to  admit that  vented refrigerants liberally and used them as cleaning agents is a norm. Leak containment was not an issue and it would not be unusual to keep topping up leaking systems with new refrigerant. These refrigerants had high GWP’s (R502 = 4657). Health and Safety was not the issue that it is now. In 1974 fatal injuries in the workplace totalled 651.

Now it is illegal to vent refrigerant to atmosphere in most of the world. A young engineer accepts they would be disciplined if they did not reclaim, recover and recycle refrigerants. R32 is mildly flammable and has a GWP of 675, and we are actively pursuing lower GWP alternatives. Health and Safety is now a real issue and anything that is potentially combustible or flammable raises eyebrows.


All A2L alternatives are mildly flammable. All new refrigerants being tested are A2L. Mild flammability is here to stay and our industry needs to adapt to working with these products.

Whilst you may assume that mildly flammable refrigerants are “not really flammable”, your customer or owner might have a different perception and they will expect you to be professional in the handling of the product.

They are  likely to see a flammable label on the side of their unit. It will not say “mildly flammable”. All installers should be aware of this and be prepared to provide answers. “It’s not really flammable, trust me” may not placate a business owner or health and safety manager. People see what they see. A flammable label is a flammable label.

What does A2L mean?

Typical refrigerants that we use in the industry are split into three safety classifications.

A1: low toxicity, non-flammable
A2: low toxicity, lower flammability
A3: low toxicity, higher flammability

There is a proposal for a new classification to allow the industry to accommodate new lower GWP products, most of which are “A” Class refrigerants. The proposal is for “A2L” refrigerants which is lower flammability with lower flame propagation. By this we mean that any flame will have a burning velocity of less than 10cm/sec.

So just how flammable are A2L refrigerants? There is a lot of conjecture on this issue. Some are more flammable that others but they all have lower flammability, lower flame propagation levels.

Let’s look at R32 as our example. This is the proposed solution for commercial air conditioning.

Is it flammable? Yes

What do I need to ignite R32?
A concentration limit (or LFL) of between 13 – 30
An MIE (Minimum Ignition Energy) of 30 to 100mJ
A flame higher than 600°C
A constant supply of oxygen

Can I set fire to it? Yes

Will my engineers try to set light to it? I know of engineers who have applied a flame to leaking propane in fridge cabinets so who is to say?

Can a spark from a light switch ignite it? No

What is the most likely circumstance of a flame being produced? An engineer, most likely in error, or the product in the wrong hands.

Will this be a substantial flame requiring emergency services? Not unless you keep holding a flame to the exposed refrigerant or if it creates a fire by setting light to another material. The propagation is very low and the flame will normally self-extinguish.

Assuming all of the above, how likely is it that R32 will ignite on site? Very unlikely (and I write that so as not to implicate myself by saying “no”. But there is never a “never”)

But surely with all of the above it is possible? Yes.

What would the most likely scenario be? A system that is being installed may have a leak and an engineer from any trade may be using a constant flame in the vicinity of that leak. Poor practice may cause this but it is very unlikely. The chances of a similar set of scenarios occurring when the system is installed are equally unlikely.

So there is nothing to worry about then? If you take that approach, then you are more likely to have an incident.

What is LFL

As per the above, oxygen, MIE, a temperature of over 600°C and the concentration limit are the ingredients for combustion.

We are unlikely to exceed the MIE in an installed environment. As stated earlier, the energy from a switch should not exceed the MIE.

It is, of course, possible to apply a flame of over 600°C to a leaking system and this will create a flame. An example of this can be seen on our YouTube channel by clicking here.

The Lower Flammability Limit or LFL is essentially the minimum concentration limit that is required for the product to become potentially combustible. Anything less than the LFL means that combustion is not possible.

LFL can be presented as a number or in volume. Examples for R32 are 0.307 or 13.3%.

There is also an Upper Flammability Limit or UFL. Any concentration greater than this means that the product mix with oxygen is too rich and therefore the product cannot combust.

So how likely is it to exceed the LFL in day-to-day air conditioning applications?

For split system applications it is unlikely unless a product has been significantly oversized for the application. VRF may pose other questions due to total refrigerant charge but at present there are no VRF products on the horizon so we do not need to consider that scenario at the moment.

I will revisit this when we look at design and application. This is the one area that will need consideration as it will directly affect what products come to market and how we apply our products to comply with current and forthcoming legislation. Going forward, LFL will become an important buzzword in air conditioning design and application.


To summarise the important issue of flammability for now:

Ensure your health & safety procedures are up to date.
• Consider further training on hydrocarbons and adjust your policies and procedures to fit around the handling of those products
• Be aware that your customer may have questions that they will be seeking assurance on.
• Yes, your customer may have a gas supply but don’t use that as a lazy argument. Be knowledgeable and professional in your answers and advice.
Respect R32 and A2L.
Don’t cut corners. If R410A allows you to cut some corners, then stop now. R32 may not be so forgiving.

most of the statement are adopted from Cooling Post Newsletter http://www.coolingpost.com/