A2L & A3 refrigerants: EPA 608 Practice Questions

What does the ASHRAE 34 safety class A2L mean?

A2L is a subclass of class 2 for refrigerants that are lower toxicity and mildly flammable, with a burning velocity of 10 cm/s or less.

Which safety class does R-32 have?

R-32 is A2L: lower toxicity and mildly flammable. It is used in many new split systems and is a component of R-410A and R-454B.

Which of these refrigerants is classified A2L?

R-454B is A2L. R-410A is A1, R-290 is A3 and R-123 is B1.

Which safety class does propane (R-290) have?

Hydrocarbons such as R-290 and R-600a are A3: lower toxicity but higher flammability. They are limited to small charges in self-contained equipment.

Which statement about R-1234yf is correct?

R-1234yf is an HFO classified A2L, with zero ODP and a GWP of about 1–4. It is common in vehicles and is a component of R-454B.

What kind of recovery machine may be used on a system charged with R-32?

Equipment for flammable refrigerants is tested to a separate standard (Appendix B4) and designed to avoid sparks. An older A1-only machine can be an ignition source.

How is a cylinder for a flammable refrigerant such as R-454B marked so it is not confused with an A1 cylinder?

Flammable refrigerant cylinders carry a red band or marking, and most have left-hand threaded valve outlets (an industry practice under AHRI guidance) so A1 hoses and adapters do not connect by mistake.

Before brazing on a system that contained R-32, what must be done?

Remove all refrigerant, evacuate, then purge with nitrogen so no flammable mixture remains before applying a flame.

Which practice reduces the fire risk when servicing an A2L system?

A2L refrigerants need both a flammable concentration and an ignition source to burn. Ventilation and keeping sparks and flames away prevent both.

Why are R-32 and R-454B replacing R-410A in new residential air conditioners?

All three have zero ODP. R-32 (GWP about 675) and R-454B (about 466) have roughly a quarter to a third of R-410A's GWP (about 2,088).

Compared with an A3 refrigerant such as propane, how does an A2L refrigerant behave?

A2L refrigerants need more energy to ignite and burn slowly (10 cm/s or less), but they can still burn and release toxic gases such as hydrogen fluoride.

Why is a halide torch leak detector not suitable for an R-454B system?

A halide torch reacts to chlorine, which HFC and HFO refrigerants do not contain, and its flame is an ignition source. Use an electronic detector rated for A2L.