Mixed Deck — All A2L Topics Flashcards

After brazing a repair on an A2L system, what tests must be performed before recharging?

Answer: Pressure test with nitrogen to verify the repair is leak-free, then evacuate to 500 microns to remove moisture, then leak test all connections before charging

Post-repair testing follows a sequence: verify the repair integrity (pressure test), prepare the system (evacuation), then verify all connections (leak test) before introducing flammable refrigerant.

What is the correct procedure for recovering A2L refrigerant before a major repair?

Answer: Recover into an approved DOT cylinder using A2L-rated recovery equipment, documenting the amount recovered

EPA regulations prohibit venting ALL refrigerants, including A2L. Proper recovery into approved cylinders using rated equipment is mandatory, with the amount documented.

When performing a standing pressure test on an A2L system, what gas must be used?

Answer: Dry nitrogen — never pressurize with oxygen, air, or refrigerant for testing

Nitrogen is inert (non-flammable, non-reactive) and safe for pressure testing. Compressed air contains moisture and oxygen; oxygen with A2L refrigerant residue could create a dangerous mixture.

According to ASHRAE 34, what does the '2L' in a refrigerant classification like R-32 (A2L) specifically indicate regarding flammability?

Answer: It has lower flammability, characterized by a low burning velocity.

The '2L' classification signifies 'lower flammability,' which is defined by a burning velocity of 10 cm/s or less. This distinguishes A2L refrigerants from A2 (flammable) and A3 (higher flammability) categories, which have higher burning velocities and pose a greater fire risk.

During brazing on a system that previously contained A2L refrigerant, what must be done BEFORE applying heat?

Answer: The system must be completely evacuated of refrigerant AND purged with nitrogen to eliminate any flammable residue

All refrigerant must be recovered first, then the system must be purged with dry nitrogen. Any residual A2L refrigerant exposed to brazing temperatures will decompose into toxic hydrogen fluoride.

Where should a fixed refrigerant leak detector sensor be mounted in a room with an A2L system?

Answer: Near floor level, as A2L refrigerants are denser than air

Most A2L refrigerants are heavier than air and settle at floor level when leaked. Sensors must be positioned where the gas accumulates first — typically within 12 inches of the floor.

What penalties can result from improper handling of A2L refrigerants under federal law?

Answer: Fines up to $44,539 per day per violation under the Clean Air Act, plus potential criminal penalties

EPA enforcement under the Clean Air Act carries significant civil penalties per violation per day. Criminal penalties including imprisonment are possible for knowing and willful violations.

What type of fire extinguisher is most appropriate for a fire involving the release of a flammable A2L refrigerant?

Answer: Class B or ABC (Dry Chemical)

A2L refrigerants are flammable gases, which fall under the category of Class B fires (flammable liquids and gases). A dry chemical extinguisher rated for Class B or, more commonly, Class ABC, is effective at interrupting the chemical reaction of the fire.

Why is it critical to know that A2L refrigerants are heavier than air when responding to a leak?

Answer: It means they will accumulate in low-lying areas like pits and basements.

Because they are denser than air, A2L refrigerant vapors will sink and accumulate in the lowest areas, such as basements, crawlspaces, or service pits. This creates a hidden and concentrated flammable hazard that must be specifically checked for.

How should A2L refrigerant cylinders be arranged in a storage area?

Answer: Upright, secured to prevent tipping, with valve protection caps installed, organized by refrigerant type, and with full/empty cylinders separated

Proper cylinder storage organization prevents accidents, enables inventory management, and ensures cylinders can be accessed safely.

What must a technician verify about a recovery cylinder before using it for A2L refrigerant?

Answer: The cylinder is DOT-approved, within its retest date, rated for the specific refrigerant's pressure, and properly labeled for A2L use

Recovery cylinders must be DOT-approved, currently certified (retest dates), pressure-rated for the specific refrigerant, and properly labeled. Using an expired or under-rated cylinder is both dangerous and illegal.

What additional tool is essential for verifying A2L system charge limits during installation?

Answer: A measuring tape and calculator — to measure room dimensions and calculate maximum allowable charge based on the RCL

Calculating the charge limit requires measuring the room where the indoor unit is installed (length × width × height) and multiplying by the RCL. A tape measure and basic math are essential tools.

What does 'GWP' stand for and how is it calculated for a refrigerant?

Answer: Global Warming Potential — the ratio of heat trapped by a gas relative to CO₂ over a specified time horizon (typically 100 years)

GWP (Global Warming Potential) measures how much heat a greenhouse gas traps relative to the same mass of CO₂ over a specified time period. A 100-year GWP of 675 for R-32 means 1 kg of R-32 traps 675 times as much heat as 1 kg of CO₂ over 100 years. CO₂ itself has a GWP of 1 by definition.

A technician is transporting several cylinders of an A2L refrigerant in a service van. According to DOT guidelines and best practices, what is a key requirement for transporting these cylinders safely?

Answer: Cylinders must be secured in an upright position.

A2L refrigerant cylinders are equipped with a pressure relief valve at the top. Transporting them in an upright position ensures that the valve is in the vapor space of the cylinder. If the cylinder is over-pressurized, this allows vapor to vent instead of liquid, which is a much safer release.

Why is it important for technicians to have formal training in handling A2L refrigerants?

Answer: To reduce the risk of accidents and ensure proper handling

Formal training in handling A2L refrigerants is essential for technicians to reduce the risk of accidents and ensure proper handling. Given the mild flammability of A2L refrigerants, specialized knowledge is required to prevent leaks, fires, and other hazards during installation, servicing, and decommissioning. This training protects technicians, occupants, and the environment from potential dangers.

What is the proper way to check if a recovery cylinder is empty before switching to a different refrigerant?

Answer: Weigh the cylinder and compare to its tare (empty) weight stamped on the cylinder

Weighing the cylinder against its tare weight is the only reliable way to confirm it's truly empty. Residual liquid refrigerant may not be detected by pressure alone.

What is the most effective way for an HVAC company to prepare its workforce for the A2L transition?

Answer: Develop a phased training plan: awareness training for all staff now, technical certification for technicians before A2L equipment arrives, and ongoing updates as codes evolve

A phased approach ensures the entire organization is prepared: awareness first, then deep technical training timed before equipment availability, with ongoing education as the field evolves.

What happens if the calculated maximum charge exceeds the system's design charge requirement?

Answer: Consider a different refrigerant, a different system design, or install mitigation measures like leak detection with ventilation

If the charge limit is too restrictive, options include selecting a refrigerant with a higher RCL, redesigning the system with less charge, or adding mitigation systems like leak detectors that trigger ventilation.

If a person is exposed to high concentrations of A2L refrigerant vapor, what first aid should be administered?

Answer: Move them to fresh air immediately, monitor breathing, and seek medical attention

Immediate removal to fresh air is critical. High-concentration exposure can cause dizziness, asphyxiation, or cardiac effects. Medical evaluation should follow any significant exposure.

Which ASHRAE standard specifically addresses safety requirements, including ventilation, for systems using lower flammability (A2L) refrigerants?

Answer: ASHRAE 15.2

ASHRAE 15.2 is the Safety Standard for Refrigeration Systems Using Lower Flammability (A2L) Refrigerants and provides ventilation and other safety requirements specific to these refrigerants.