Question 1

Under ASHRAE Standard 34, what does the "2L" in an A2L refrigerant classification indicate?

Accepted Answer

In ASHRAE 34, the letter (A) is the toxicity class — A means lower toxicity — and the number/suffix is the flammability class. "2L" means lower flammability with a low burning velocity, i.e. mildly flammable.

Question 2

Which of the following refrigerants is classified as A2L?

Accepted Answer

R-454B is an A2L (mildly flammable, low-GWP) refrigerant. R-410A, R-22, and R-134a are all A1 (non-flammable) refrigerants.

Question 3

Compared with an A1 refrigerant such as R-410A, an A2L refrigerant is:

Accepted Answer

A1 refrigerants are non-flammable. A2L refrigerants are mildly (lower) flammable with a low burning velocity, which is why they require additional handling precautions.

Question 4

A2L refrigerants such as R-32 and R-454B are replacing R-410A primarily because they have a lower:

Accepted Answer

The main driver is Global Warming Potential. A2Ls like R-32 (GWP ~675) and R-454B (GWP ~466) have far lower GWP than R-410A (GWP ~2088), which is why they are being adopted under the HFC phasedown.

Question 5

The EPA's HFC phasedown under the AIM Act targets reducing U.S. HFC production and consumption by what amount by 2036?

Accepted Answer

The American Innovation and Manufacturing (AIM) Act directs the EPA to phase down HFC production and consumption by 85% (relative to baseline) by 2036, on a stepped schedule.

Question 6

Which refrigerant safety group is NON-flammable?

Accepted Answer

A1 is the non-flammable class. A2L is mildly flammable (low burning velocity), A2 is flammable, and A3 is higher flammability.

Question 7

Which of the following is an A3 (higher-flammability) refrigerant?

Accepted Answer

R-290 (propane) is an A3, higher-flammability refrigerant. R-32 and R-454B are A2L (mildly flammable), and R-410A is A1 (non-flammable).

Question 8

When working with A2L refrigerants, technicians must avoid:

Accepted Answer

Because A2Ls are mildly flammable, open flames and other ignition sources must be kept away from areas where refrigerant could leak and accumulate. Recovery, scales, and PPE are all still required.

Question 9

Equipment designed for A2L refrigerants often includes which safety feature not typically required on A1 systems?

Accepted Answer

A2L equipment commonly includes a built-in refrigerant leak-detection sensor (and mitigation, such as a fan) per safety standards like UL 60335-2-40, to manage the mild flammability risk.

Question 10

As of January 1, 2025, new residential air-conditioning and heat-pump systems made in the U.S. must generally use refrigerants below a 700 GWP limit, which has driven adoption of:

Accepted Answer

The sector-based GWP limit (under 700 GWP for new residential AC/heat pumps as of Jan 1, 2025) phases out R-410A in new equipment in favor of lower-GWP A2L refrigerants such as R-454B and R-32.

Question 11

Which low-GWP A2L refrigerant is widely used in modern automotive air-conditioning systems?

Accepted Answer

R-1234yf is a low-GWP A2L refrigerant that has largely replaced R-134a in new automotive air-conditioning systems.

Question 12

Because A2L refrigerants are mildly flammable, manufacturers and codes limit the maximum refrigerant ____ allowed for a given room or space.

Accepted Answer

A2L safety standards set a maximum refrigerant charge based on the size of the conditioned space, limiting how much refrigerant can be present so a leak cannot create a flammable concentration.

A2L Refrigerants (2026) Practice Questions

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