A2L Flammability Characteristics and Metrics 2

Question 1

What is the Lower Flammability Limit (LFL) of R-32, one of the primary A2L refrigerants?

Accepted Answer

14.4% by volume in air

Answer

R-32 has an LFL of approximately 14.4% by volume in air. This high LFL compared to A3 refrigerants means a larger concentration is needed to create a flammable mixture, which contributes to its classification as mildly flammable (A2L) rather than highly flammable.

Question 2

What does the 'L' suffix in the A2L flammability classification specifically denote?

Accepted Answer

Low burning velocity of 10 cm/s or less

Answer

The 'L' in A2L stands for 'lower flammability' specifically referring to a maximum burning velocity (flame propagation speed) of 10 cm/s or less at 60°C and 101.3 kPa. This distinguishes A2L refrigerants from standard A2 refrigerants which have higher burning velocities.

Question 3

Which of the following metrics is NOT used by ASHRAE 34 to define the flammability class of an A2L refrigerant?

Accepted Answer

Ozone depletion potential (ODP)

Answer

Ozone depletion potential (ODP) is an environmental metric and is not part of the ASHRAE 34 flammability classification system. ASHRAE 34 flammability classification uses burning velocity, heat of combustion, and flammability limits (LFL and UFL) to assign refrigerants to classes 1, 2L, 2, or 3.

Question 4

R-454B (Opteon XL41) has a GWP of approximately how much compared to R-410A's GWP of 2,088?

Accepted Answer

466 — roughly 78% lower GWP than R-410A

Answer

R-454B has a GWP of approximately 466, which is roughly 78% lower than R-410A's GWP of 2,088. This dramatic GWP reduction while maintaining similar thermodynamic performance to R-410A is why R-454B is a leading replacement refrigerant for residential and light commercial air conditioning systems.

Question 5

What is the Upper Flammability Limit (UFL) significance in A2L refrigerant safety assessments?

Accepted Answer

It defines the maximum concentration above which the mixture is too rich to ignite

Answer

The UFL (Upper Flammability Limit) is the highest concentration of refrigerant in air above which the mixture is too fuel-rich (oxygen-deficient) to sustain combustion. Together with the LFL, it defines the flammable range. Concentrations above the UFL are non-flammable because there is insufficient oxygen to support burning.

(A2L) A2L Low GWP Flammable Refrigerant Safety Certification Practice Test

(A2L) A2L Low GWP Flammable Refrigerant Safety Certification Practice Test

A2L Flammability Characteristics and Metrics 2