Low-GWP Refrigerant (LGWP)
What this domain tests
The LGWP domain checks whether you can identify low-GWP refrigerants, explain the regulatory and safety drivers, and apply A2L handling rules without treating them as drop-ins for R-410A or R-22.
Core rules
- GWP is a 100-year CO2-equivalent multiplier. R-410A is about 2,088; R-32 about 675; R-454B about 466; R-1234yf is near 4. Lower GWP reduces direct emissions but does not by itself change charge, pressure, or service risk.
- Key low-GWP alternatives, including R-32, R-454B, and R-1234yf, are ASHRAE A2L: lower flammability, lower burning velocity (≤10 cm/s), not A3. A2L systems need ignition-source control, leak detection or mitigation where required, and components listed for the refrigerant.
- The AIM Act phases down HFC production and consumption; EPA Section 608 refrigerant management rules still apply. Never vent refrigerant. Recover, recycle, or reclaim per equipment and cylinder rules.
- Zeotropic blends such as R-454B have glide and fractionate. Charge as liquid from the cylinder unless the manufacturer says otherwise; use pressure-temperature data with bubble and dew points, not a single saturation temperature.
- A2L leak detectors and flammable-gas sensors are refrigerant-specific. Do not substitute an A1 detector or a generic combustible-gas sensor without manufacturer approval.
Worked example
A site leaks 1 kg of R-410A. Using AR4 GWPs: 1 kg × 2,088 = 2,088 kg CO2e. Replacing that charge with R-454B at GWP 466 gives 1 kg × 466 = 466 kg CO2e, a 78% reduction: (2,088 − 466) ÷ 2,088. That is the direct-emission benefit. It does not prove the system can use R-454B: you still verify A2L listing, charge limit, ventilation, detector, and components.
Traps
Assuming A2L is a drop-in; treating A2L as A3; ignoring glide; using R-410A PT charts; charging vapor into a zeotropic blend; bypassing a refrigerant sensor; and failing to check the nameplate or manual for charge and mitigation requirements.