A2L Refrigerants - myths and realities. Part 2 - Flammability

In Part 1, we looked at A2L Refrigerants and why the air conditioning industry is faced with moving from R410a to R32. 

In part 2 we will continue the "idiots guide" theme where possible to make this subject easier to understand. This is possibility the lengthiest article in this series and certainly the most explosive subject matter :-) . 

Hopefully we now understand why the industry is moving to A2L refrigerants. This is to comply with EU requirements to phase down CO2 emissions. Put simply, we can produce three bottles of R32 for one bottle of R410a. This means three times as much product for roughly the same equivalent potential CO2 emissions. 

Now let's move on to the main issue with A2L Refrigerants. They are flammable. Or, to be exact, they are "mildly flammable". But what does this mean?

"Mildly Flammable"

I have heard some talk in the industry that "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. 

THEN: In the 1970's - 1990's we used CFC's and HCFC's mixed with mineral oil. This was a potentially combustible combination. Engineers agree that they vented refrigerants liberally and used them as cleaning agents. 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 totaled 651 (hse.gov.uk)

NOW: R32 is mildly flammable. It is illegal to vent refrigerant to atmosphere. A young engineer accepts they would be disciplined if they did not reclaim, recover and recycle refrigerants. The GWP of R32 is 675 and we are actively pursuing lower GWP alternatives. In 2014-2015 fatal injuries in the workplace totaled 92 (hse.gov.uk). 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 (examples shown below - over 80 at the last count) are A2L. Mild flammability is here to stay and our industry needs to adapt to working with these products. 

Remember: if you have a valid F-Gas certificate then you are qualified to use HFC Refrigerants. R32 is a HFC. Remember that safety bit at the beginning of your training? It is now relevant. 

Whilst you may assume that mildly flammable refrigerants are "not really flammable", your client may have a different perception and they will expect you to be professional in the handling of the product. 

Your client is 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 HVAC 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 10 cm per second. 

This reclassification is important to the future of the HVAC industry. Presently, A2 refrigerants are banned from public buildings in Spain, Italy and France. This reclassification to A2L will allow these refrigerants to be used widespread throughout Europe. However, for this to happen legislation needs to be rewritten and republished. The legislation that is affected is not just BS: EN378 but also EN60335-2

For those who have noticed the drip-feed of R32 product into the market you will note that the largest offering is a 5kW Domestic Wall Mount. 

It is no co-incidence that half of Western Europe will not allow R32 in public installations and commercial air conditioning product is not yet available in the UK. We all draw from similar stock and it is vitally important that legislation is rewritten and republished to allow the reclassification to A2L refrigerants. Once done we should see an influx of R32 product. 

EN60335-2?

Our industry is governed almost solely by BS: EN378. This governs the life cycle of an air conditioning system from initial design through to installation, servicing and end of life. 

EN60335 is a piece of legislation which covers the safety of "Household and Similar Electrical Appliances". Air Conditioning products are already covered by this legislation but it has never previously been as issue to the industry. However, now that we have a "flammable" refrigerant inside our pipes it becomes a significant issue which brings this legislation into play. 

I will cover the implications of this when we look at design and application considerations in a future post. 

Flammability

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) A concentration limit (or LFL) of between 13 - 30%, b) a MIE (Maximum Ignition Energy) of 30 to 100mJ c) a flame higher than 600°C, d) 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 it will R32 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. 

I keep hearing about "LFL". What is this?

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 (Minimum Ignition Energy) 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.

• If you are F-Gas trained, then you are qualified to handle R32. 
• 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.

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CPD Approved training on A2L refrigerants is available from Logicool. Call 01283 218277 or email [email protected] for more information.