REFCOM, the British F-gas certification body, has published a technical bulletin “WORKING WITH LOWER FLAMMABILITY REFRIGERANTS”, as a number of HFC alternatives chemicals of blends are “mildly flammable” (see Note) of an A2L flammability level (so-called).
The bulletin documents the changes to working practices required when working with A2L refrigerants, proposing best practice in installation, service, maintenance and repair work.
It also deals with the new version of the European Standard EN 378 “Refrigerating systems and heat pumps – Safety and environmental requirements” incorporating new requirements for A2L refrigerants, and introducing a new method for calculating the maximum permissible refrigerant charge in a system, based on both toxicity and flammability.
On this matter, AREA, the European contractors association, has developed a free smartphone application, designed to calculate concentration and flammability safety limits under EN378 and to advise if a design is compliant or requires further investigation.
Note : Mildly flammable (A2L) refrigerants tend to be less easy to ignite, and have a lower burning velocity of ≤ 10 cm/s. They are therefore considered to be safe for use in approved systems and can be considered safe for general handling, with certain provisos.