A2L and A3: the better you know them, the better you use them

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Credits: IOR

A2L and A3 refrigerants increasingly belong to refrigeration daily practices. A good professional training and the compliance with standards are a fundamental prerogative for their safe use.

Among the refrigerants that are increasingly establishing themselves on the market because they comply with the F-gas regulation, many are flammable (Class A3 and A2L). However, three elements simultaneously are necessary to give birth to a combustion process: 1) the leak of a flammable refrigerant that mixes with air to give 2) the right mixture that must get in touch with 3) an ignition source (flame or spark).
The “right mixture” – affirm Jane Gartshore, Cool Concerns and Chris Playford, Foster & Gamko in a webinar organized by IOR British refrigeration Institute- varies according to the refrigerant class. Concerning A2L refrigerants, we need a bigger quantity of refrigerant compared to those in A3 class, to be able to give birth to a flammable mixture. A mixture of refrigerant/air with 14% of R32 (A2L), for instance, is necessary to start a combustion process but with 2% only for an A3. This is the substantial difference between a refrigerant in class A3 and a refrigerant in class A2L: the sufficient refrigerant quantity in air to generate a combustion is ≤ a 3% in case of an A3 and higher than this value in case of A2L. in addition to that, the combustion heat originated in case of an A3 is bigger than the one of an A2. Finally, the flame propagation is much faster in the case of an A3 than in an A2L. in brief, A2L are more difficult to ignite than an A3 and, when this happens, effects are minor.
Among the possible ignition sources, the sparks from electric appliances can hardly give birth to a combustion of an A2L whereas they might succeed in it with an A3. Anyway, components in compliance with ATEX Directive are not ignition source for any refrigerant. If, during a maintenance intervention, some ATEX components were replaced, also the new components must be substituted, to avoid modifying the safety characteristics of the plant or of the machine.

Working safely with flammable refrigerants
We cannot summarize in few words what working safely with flammable refrigerants means, Gartshore affirms, but we can underline some fundamental concepts that are always valid in all situations. With A3 and A2L refrigerants, it is always valid: • Using ATEX components wherever they are provided for; • Never executing the retrofit of HFC systems with flammable refrigerants, never putting some flammable refrigerant in a circuit that has not been designed for such refrigerant; • Keeping the refrigeration charge as low as possible, by using evaporators and condensers that allow doing it; • Using secondary detection systems, additional ventilation and detection systems; • The work area where you operate with the flammable refrigerant must have a radius of at least 3 m; it must be equipped with systems of ventilation, refrigerant leak detection and extinguishers at disposal; • Detection systems must be reliable, safe and sensitive; • Plants must be correctly emptied and vacuum, with nitrogen injection and use of ATEX pumps; • Before any operation of plant brazing or opening, it is necessary to empty it completely and to fill it with nitrogen;

This text results from a webinar organized by IOR. For further information, please go to www.ior.org.uk