What do A1, A2L and A3 mean? Understanding refrigerant safety classes
The ASHRAE 34 safety code shows both the toxicity and flammability of a refrigerant, helping you choose and install it safely.
Every refrigerant grade has a safety classification under ASHRAE 34, made of one letter and one number.
The letter: toxicity
- A — lower toxicity
- B — higher toxicity; requires ventilation and leak detection
The number: flammability
- 1 — no flame propagation
- 2L — lower flammability; hard to ignite with a slow burning velocity
- 2 — flammable
- 3 — higher flammability
Common examples
| Class | Examples |
|---|---|
| A1 | R-22, R-134a, R-410A, R-404A, R-448A |
| A2L | R-32, R-454B, R-1234yf |
| A2 | R-152a, R-141b |
| A3 | R-290 (Propane), R-600a (Isobutane) |
| B1 | R-245fa |
What technicians should know
- A2L and A3 refrigerants may only be used in equipment designed for them — never as a replacement in systems designed for A1 refrigerants.
- A3 refrigerants have maximum charge and installation-space limits; they should be handled by trained technicians.
- Always check storage and handling details in the product SDS.
SDS documents for ORAFON and Solstice® products are available under TDS/SDS documents.