EPA 608 Core Study Guide
The Core section is required no matter which type you take, and it's where most people lose points. It's 25 questions and you need 18 right (70%). Here's what it covers and what to memorize.
Ozone depletion and why the rules exist
- The ozone layer is in the stratosphere. It blocks ultraviolet (UV) radiation. Ozone at ground level is a pollutant; ozone up high is protective.
- Chlorine is the problem. CFCs (like R-12) and HCFCs (like R-22) contain chlorine. When they drift into the stratosphere, UV light breaks them apart and the chlorine destroys ozone. One chlorine atom can break down thousands of ozone molecules.
- CFCs are worst, HCFCs less, HFCs zero. HFCs (R-410A, R-134a) and HFOs (R-1234yf) contain no chlorine, so they don't deplete ozone. Many HFCs do have a high global warming potential (GWP), which is why the AIM Act is phasing them down.
- Health effects of ozone loss: more skin cancer and cataracts, weaker immune systems, crop damage.
The law: Montreal Protocol and the Clean Air Act
- Montreal Protocol (1987): the international treaty that phased out CFCs and HCFCs.
- Clean Air Act Section 608: the US law for stationary refrigeration and AC. It sets technician certification, the venting ban, recovery rules and leak repair.
- Section 609 covers motor vehicle AC, not stationary equipment.
- Penalties for violations run tens of thousands of dollars per day, per violation, and EPA pays rewards to people who report illegal venting.
The venting prohibition
It's illegal to knowingly vent CFC, HCFC, HFC or substitute refrigerants while servicing, maintaining, repairing or disposing of equipment.
- De minimis releases are not violations. That's the small amount released while you're doing the job right, such as when connecting and disconnecting hoses during proper recovery.
- Nitrogen can be vented. Pure nitrogen used for a holding charge or leak test is fine to release. Refrigerant left in a system, or refrigerant mixed with air or nitrogen, is not.
The 3 Rs: recover, recycle, reclaim
| Term | What it means |
|---|---|
| Recover | Remove refrigerant and store it in an external container. No testing or processing required. |
| Recycle | Clean it for reuse, usually on site, by separating oil and passing it through filter-driers. |
| Reclaim | Process it to new-product purity (the AHRI 700 standard) and verify with lab analysis. Done by EPA-certified reclaimers. |
- Recovered or recycled refrigerant can go back into the same system or another system owned by the same owner.
- To change hands (sell it to a different owner), it must be reclaimed first.
Recovery equipment and dehydration
- Recovery equipment must be certified by an EPA-approved testing organization (such as AHRI or UL).
- Dehydration: in a deep vacuum, water boils at room temperature, turns to vapor and gets pulled out by the pump. A micron gauge proves the system is dry. Connect it at the system, not at the pump.
- Speed up evacuation with core removal tools and short, large-diameter hoses. Heat the system if it's cold; cold slows moisture removal.
Cylinders
- Disposable cylinders are for virgin refrigerant and are never refilled. When empty, recover any vapor, render them useless and recycle the metal.
- Recovery cylinders are refillable, DOT-approved, with a gray body and yellow top.
- Fill to 80% or less of capacity by liquid volume, so liquid has room to expand. An overfilled cylinder can rupture.
- Never heat a cylinder with an open flame or above 125°F, and keep cylinders secured upright.
Safety
- Oxygen displacement: refrigerant vapor is heavier than air. In basements, crawl spaces and equipment rooms it can push out oxygen. High concentrations can also cause heart arrhythmias.
- Decomposition: heated refrigerant (from a torch or hot surface) can form phosgene gas and acids. Recover before brazing.
- Leak testing: use dry nitrogen with a regulator and relief valve. Never use oxygen or compressed air. Oxygen and oil can explode.
- Personal protection: safety glasses and gloves. Liquid refrigerant causes frostbite on contact.
Refrigerant safety classes
The classification comes from ASHRAE Standard 34. The letter is toxicity, the number is flammability.
| Class | Meaning | Examples |
|---|---|---|
| A1 | Lower toxicity, no flame propagation | R-410A, R-134a, R-22 |
| A2L | Lower toxicity, lower flammability | R-32, R-454B, R-1234yf |
| A3 | Lower toxicity, higher flammability | R-290 (propane), R-600a |
| B1 | Higher toxicity, no flame propagation | R-123 |
The 2026 question bank adds general A2L and A3 questions, so know these classes and the basics: use A2L-rated tools, control ignition sources, ventilate, and follow the manufacturer's procedures.
Leak repair: the numbers to memorize
| Appliance type | Leak rate that triggers repair |
|---|---|
| Comfort cooling | 10% per year |
| Commercial refrigeration | 20% per year |
| Industrial process refrigeration | 30% per year |
- The Section 608 rule applies to appliances with 50 lb or more of ozone-depleting refrigerant.
- Since January 1, 2026, the AIM Act rule applies the same thresholds to appliances with 15 lb or more of HFC (or substitute with GWP above 53).
- Once the threshold is exceeded, the leak generally must be repaired within 30 days, with verification tests.
Shipping and sales
- Only certified technicians can buy refrigerant for stationary equipment.
- Cylinders shipped for reclaim must be DOT-approved and labeled with the refrigerant type and amount.
- Your certification never expires. Keep your card.
Test yourself: Core practice questions
27 questions in this set. Passing on the real exam is 70% per section (18 of 25).