Which statement about HFO refrigerants such as R-1234yf is correct?
HFOs contain no chlorine and have a low global warming potential. EPA treats them as a subset of HFCs, made of hydrogen, fluorine and carbon. They are still non-exempt substitutes, so they must be recovered.
- They contain no chlorine and have a low GWPCorrect answer
- They contain less chlorine than HCFCs do
- They are exempt from the venting prohibition
- They have a higher GWP than R-410A does
Why “They contain no chlorine and have a low GWP” is correct
EPA describes HFOs as a subset of HFCs with short atmospheric lifetimes and lower global warming potentials. Like other HFCs they are made of hydrogen, fluorine and carbon, with no chlorine. EPA lists HFO-1234yf at a GWP of 1, against 2,088 for R-410A.
Source: EPA: Fluorinated Gas Emissions; EPA: Technology Transitions GWP Reference Table; EPA: Refrigerant Management Fact Sheet for Technicians
Why the other answers are wrong
- They contain less chlorine than HCFCs do — HFOs contain no chlorine at all, which is why they do not deplete ozone.
- They are exempt from the venting prohibition — EPA lists HFOs among the non-exempt substitute refrigerants, so they must be recovered.
- They have a higher GWP than R-410A does — EPA's reference table lists HFO-1234yf at 1 and R-410A at 2,088, so the HFO is far lower.
The source, word for word
Newly developed hydrofluoroolefins (HFOs) are a subset of HFCs and are characterized by short atmospheric lifetimes and lower GWPs.
non-exempt substitute refrigerants, e.g., hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs) and blends thereof.
A compound consisting of hydrogen, fluorine, and carbon.
HFO compared with an HFC
The big difference is GWP. On recovery, the two are treated alike.
| HFO-1234yf | R-410A (HFC blend) | |
|---|---|---|
| Contains chlorine | No | No |
| Depletes ozone | No | No |
| 100-year GWP | 1 | 2,088 |
| Must be recovered | Yes | Yes |
Low GWP is not an exemption
HFOs are not on the list of exempt substitutes in 40 CFR 82.154(a)(1). What may be released shows which substances are. HFOs are also one of the examples of a substitute in the definition at 40 CFR 82.152.
Keep practicing
- Refrigerant types: CFC, HCFC, HFC and HFO
- How the GWP of R-290 compares
- What CFCs, HCFCs and HFCs have in common
- EPA 608 Core practice test
Unofficial, not affiliated with the EPA or any EPA-approved certifying organization. Questions are original practice written from public EPA material, not real exam questions.