ESCO Low GWP A2L Refrigerant Safety & HVACR Concepts – with Questions with
Answers and rationales
Section 1: Refrigerant Safety Classification & ASHRAE Standards (Questions 1-20)
Q1. What do the "A" and "2L" designate in the A2L safety classification?
A. Low toxicity and non-flammable
B. Lower toxicity and mild flammability with low burning velocity
C. High toxicity and flammable
D. Lower toxicity and highly flammable
Answer: B. Lower toxicity and mild flammability with low burning velocity
Rationale: This classification system from ASHRAE Standard 34 defines
refrigerants by toxicity and flammability. "A" denotes lower toxicity (vs. "B" for
higher toxicity). "2L" is a subclass of "2" for flammable refrigerants with a
,maximum burning velocity of less than 10 cm/s, making them safer than higher-
flammability A2 or A3 refrigerants.
Q2. What is the maximum burning velocity required for a refrigerant to be
classified as A2L?
A. Less than 5 cm/s
B. Less than 10 cm/s
C. Less than 15 cm/s
D. Less than 20 cm/s
Answer: B. Less than 10 centimeters per second
Rationale: The "L" in A2L stands for "low burning velocity." This property means
that even if an A2L refrigerant ignites, the flame spreads very slowly (0.1-0.3 m/s)
and is more likely to self-extinguish, which is a key safety characteristic
distinguishing A2L from higher-flammability A2 or A3 refrigerants.
Q3. According to ASHRAE Standard 34, which safety classification represents non-
flammable, lower-toxicity refrigerants like R-410A?
,A. A2L
B. A1
C. B1
D. A3
Answer: B. A1
Rationale: A1 refrigerants are lower toxicity ("A") and non-flammable ("1"). This
classification includes traditional refrigerants such as R-410A, R-134a, and R-22.
A2L signifies mild flammability, while A3 (e.g., propane/R-290) indicates highly
flammable.
Q4. Which of the following statements about A2L refrigerants is TRUE?
A. They are completely non-flammable like A1 refrigerants
B. They have a burning velocity higher than A3 refrigerants
C. They are harder to ignite than A3 refrigerants but require safety precautions
D. They have no global warming potential
, Answer: C. They are harder to ignite than A3 refrigerants but require safety
precautions
Rationale: A2L refrigerants are mildly flammable with a higher minimum ignition
energy (MIE) than A3 refrigerants. This means they require a significant ignition
source—such as an open flame—and cannot be ignited by static discharge alone.
However, they still require safety precautions during handling and servicing.
Q5. What is the approximate Global Warming Potential (GWP) of R-454B?
A. 2,088
B. 1,760
C. 675
D. 466
Answer: D. 466
Rationale: R-454B is a common replacement for R-410A. Its GWP of 466
represents about a 78% reduction compared to R-410A's GWP of 2,088, making it
compliant with regulations like the AIM Act that mandate lower-GWP
refrigerants.
Answers and rationales
Section 1: Refrigerant Safety Classification & ASHRAE Standards (Questions 1-20)
Q1. What do the "A" and "2L" designate in the A2L safety classification?
A. Low toxicity and non-flammable
B. Lower toxicity and mild flammability with low burning velocity
C. High toxicity and flammable
D. Lower toxicity and highly flammable
Answer: B. Lower toxicity and mild flammability with low burning velocity
Rationale: This classification system from ASHRAE Standard 34 defines
refrigerants by toxicity and flammability. "A" denotes lower toxicity (vs. "B" for
higher toxicity). "2L" is a subclass of "2" for flammable refrigerants with a
,maximum burning velocity of less than 10 cm/s, making them safer than higher-
flammability A2 or A3 refrigerants.
Q2. What is the maximum burning velocity required for a refrigerant to be
classified as A2L?
A. Less than 5 cm/s
B. Less than 10 cm/s
C. Less than 15 cm/s
D. Less than 20 cm/s
Answer: B. Less than 10 centimeters per second
Rationale: The "L" in A2L stands for "low burning velocity." This property means
that even if an A2L refrigerant ignites, the flame spreads very slowly (0.1-0.3 m/s)
and is more likely to self-extinguish, which is a key safety characteristic
distinguishing A2L from higher-flammability A2 or A3 refrigerants.
Q3. According to ASHRAE Standard 34, which safety classification represents non-
flammable, lower-toxicity refrigerants like R-410A?
,A. A2L
B. A1
C. B1
D. A3
Answer: B. A1
Rationale: A1 refrigerants are lower toxicity ("A") and non-flammable ("1"). This
classification includes traditional refrigerants such as R-410A, R-134a, and R-22.
A2L signifies mild flammability, while A3 (e.g., propane/R-290) indicates highly
flammable.
Q4. Which of the following statements about A2L refrigerants is TRUE?
A. They are completely non-flammable like A1 refrigerants
B. They have a burning velocity higher than A3 refrigerants
C. They are harder to ignite than A3 refrigerants but require safety precautions
D. They have no global warming potential
, Answer: C. They are harder to ignite than A3 refrigerants but require safety
precautions
Rationale: A2L refrigerants are mildly flammable with a higher minimum ignition
energy (MIE) than A3 refrigerants. This means they require a significant ignition
source—such as an open flame—and cannot be ignited by static discharge alone.
However, they still require safety precautions during handling and servicing.
Q5. What is the approximate Global Warming Potential (GWP) of R-454B?
A. 2,088
B. 1,760
C. 675
D. 466
Answer: D. 466
Rationale: R-454B is a common replacement for R-410A. Its GWP of 466
represents about a 78% reduction compared to R-410A's GWP of 2,088, making it
compliant with regulations like the AIM Act that mandate lower-GWP
refrigerants.
