Refrigerant safety class (A1, A2L, A3, B2L)
Also known as: ASHRAE 34 safety class, flammability class, safety group
Short definitionA short code that says how toxic and how flammable a refrigerant is. The letter is for toxicity (A, B), the number for flammability (1, 2L, 2, 3).
The A1, A2L or A3 code next to the refrigerant in a quotation sums up where that gas can be used and with how much charge. A means lower toxicity, B means toxic. 1 does not burn at all, 2L burns with a slow flame, 2 is flammable, 3 ignites easily. The classification rests on ASHRAE 34 and ISO 817. R404A, R449A, R134a and CO₂ are A1; R32, R454C and R1234yf are A2L; propane is A3; ammonia is B2L.
In cold room work the class changes the questions asked at the site survey. With an A1 gas there is rarely an obstacle at the installation site. When an A2L is chosen, the charge is checked against the volume of the smallest room under EN 378, a detector is fitted if needed and trained staff do the work. With propane the charge per circuit cannot exceed a few hundred grams; anything more needs a machine room built to ATEX rules. Ammonia gets a separate machine room; emergency ventilation and a gas detector are mandatory.