EPA 608 Refrigerant Pressure Classes Explained
Updated October 27, 2026
Many EPA 608 questions depend on knowing whether a refrigerant is low-, medium-, high- or very high-pressure. The class decides which certification type covers the equipment and how deeply it must be evacuated. Here’s how EPA defines each class in the regulation (40 CFR 82.152), followed by free practice questions.
The four pressure classes
EPA classes an appliance by its refrigerant’s liquid-phase saturation pressure at 104°F.
| Class | Saturation pressure at 104°F | Examples named in the regulation |
|---|---|---|
| Low-pressure | Below 45 psia | R-11, R-123, R-113, R-245fa |
| Medium-pressure | 45 to 170 psia | R-114, R-124, R-12, R-134a, R-500 |
| High-pressure | 170 to 355 psia | R-22, R-407A, R-407C, R-410A, R-502 |
| Very high-pressure | Above 355 psia, or a critical temperature below 104°F | R-13, R-23, R-503, R-508A, R-508B |
Which certification covers each
| Certification | Covers |
|---|---|
| Type I | Small appliances (factory-sealed, 5 pounds of refrigerant or less) |
| Type II | Medium-, high- and very high-pressure appliances (except small appliances and motor vehicle air conditioning) |
| Type III | Low-pressure appliances, such as centrifugal chillers |
A common trap: R-134a is medium-pressure, not high-pressure. Equipment using it is still covered by Type II, which includes medium-pressure appliances.
Free practice questions
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Under EPA's definitions, R-134a is a:Answer: BEPA's regulation lists R-134a as an example of a medium-pressure refrigerant, with a saturation pressure between 45 and 170 psia at 104°F.
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Which refrigerant is an example of a low-pressure refrigerant?Answer: DR-123 has a saturation pressure below 45 psia at 104°F, making it low-pressure. It's used in centrifugal chillers covered by Type III.
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R-410A and R-22 are both:Answer: AEPA lists R-22 and R-410A as high-pressure refrigerants, with saturation pressures between 170 and 355 psia at 104°F.
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Which certification type covers medium-pressure appliances?Answer: CType II covers medium-, high- and very high-pressure appliances, other than small appliances and motor vehicle air conditioning.
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At what temperature does EPA compare saturation pressures to classify refrigerants?Answer: CEPA's definitions use each refrigerant's liquid-phase saturation pressure at 104°F.
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Which is a very high-pressure refrigerant?Answer: AR-23 is listed as very high-pressure. R-11 and R-123 are low-pressure, and R-134a is medium-pressure.
Related: required evacuation levels and the Type II practice test.
Pass the EPA 608 exam on your first try
- All 168 questions across Core, Type I, Type II and Type III
- An explanation for every answer, with the rule or principle behind it
- Unlimited practice exams per section, scored like the real test (18 of 25 to pass)