12.1 High-Yield Core Section Review
Key Takeaways
The Core section is mandatory for every EPA 608 certification type and carries 25 of the 100 Universal questions; you must pass it (18 of 25, 70%) regardless of which type you pursue.
Chlorine in the stratosphere is the ozone destroyer: one chlorine atom can destroy roughly 100,000 ozone molecules, and CFCs have the highest ODP while HFCs have zero ODP but high GWP.
The Three Rs differ by destination: Recover = remove and store, Recycle = clean for the same owner's reuse, Reclaim = process to AHRI 700 purity (by an EPA-certified reclaimer) for resale.
Knowingly venting CFCs and HCFCs (since 1992) and HFCs (since November 15, 1995) is illegal; EPA permits only de minimis releases during good-faith recovery, emissions during normal operation (such as purging and leaks), and releases of exempted substitutes.
Never fill a cylinder above 80% of liquid capacity, keep refrigerant sales records 3 years, and remember the certification never expires.
Why the Core Section Decides Your Whole Exam
The Core section is the part of the EPA Section 608 exam that you cannot avoid. Whether you sit for Type I, Type II, Type III, or the full Universal certification, you must pass Core. In the 100-question Universal format, Core supplies 25 of those questions, and you need 18 of 25 correct (70%) to clear it. Fail Core and your certification is incomplete no matter how well you do on the type sections. This is why a focused, high-density Core review is the single highest-value thing you can do in the final days before the test.
Core questions cluster into six predictable buckets: environmental science (ozone and climate), regulations (Clean Air Act, Montreal Protocol, AIM Act), refrigerant classification, the Three Rs of refrigerant management, safety, and recordkeeping/sales rules. Almost every Core item is a recall question built on a specific number, date, percentage, or definition. The exam rewards memorization here far more than reasoning, so this review is organized around the facts that appear most often.
Environmental Science You Must Know Cold
The ozone layer sits in the stratosphere, roughly 10-30 miles up, where it absorbs harmful ultraviolet radiation. Chlorine is the element that destroys ozone: a single chlorine atom released from a chlorofluorocarbon can destroy on the order of 100,000 ozone molecules before it is deactivated.
Two yardsticks measure refrigerant harm. Ozone Depletion Potential (ODP) rates damage to the ozone layer; Global Warming Potential (GWP) rates contribution to climate change. CFCs (chlorofluorocarbons) carry the highest ODP, HCFCs (hydrochlorofluorocarbons) carry lower ODP, and HFCs (hydrofluorocarbons) have zero ODP because they contain no chlorine - but they still carry high GWP, which is why the AIM Act now phases them down.
Regulations and the Three Rs
Under the Clean Air Act (CAA), knowingly venting refrigerant during service, maintenance, repair, or disposal is illegal. The venting prohibition covers CFCs and HCFCs since 1992 and was extended to HFCs and their substitutes on November 15, 1995. EPA permits three kinds of release: tiny de minimis releases during good-faith recovery (for example, the small amount lost when connecting or disconnecting hoses), emissions during normal operation of equipment (such as purge-unit releases and leaks), and releases of substitutes EPA has exempted. The AIM Act (American Innovation and Manufacturing Act) mandates an 85% phasedown of HFC production and consumption by 2036 - a reduction, not a complete phaseout, so 15% of baseline remains.
The Three Rs are tested constantly and are easy to confuse:
| Term | What happens | Who can reuse it |
|---|---|---|
| Recover | Remove refrigerant and store it in an external container; no cleaning | Held for processing or disposal |
| Recycle | Clean refrigerant on site (oil separation, single-pass filtration) | Same owner's equipment only |
| Reclaim | Reprocess to AHRI Standard 700 purity by an EPA-certified reclaimer | Anyone - it may be resold |
Safety, Leaks, and Recordkeeping
Refrigerant vapor is heavier than air, so it displaces oxygen and collects in low or confined spaces, creating an asphyxiation hazard. Liquid refrigerant contact causes instant frostbite, and refrigerant decomposing near an open flame or hot surface can form toxic phosgene gas. For cylinders, the rule is absolute: never fill above 80% of liquid capacity, leaving 20% headspace for thermal expansion so the cylinder does not become hydrostatically overpressured.
Mandatory leak repair applies to comfort-cooling, commercial-refrigeration, and industrial-process systems containing 50 or more pounds of ozone-depleting refrigerant — and, since January 1, 2026, 15 or more pounds of HFC refrigerant under 40 CFR 84.106 (residential and light commercial AC excluded). When the leak rate exceeds the annual threshold for its system class, the leak must be repaired within 30 days of the refrigerant addition that revealed it. Finally, only certified technicians (or their employers) may purchase regulated refrigerant, and distributors must keep sales records for 3 years. The certification itself never expires.
Refrigerant Classification at a Glance
Core questions love to ask which class a refrigerant belongs to and when it was or will be phased out. Class I ozone-depleting substances are the CFCs (R-11, R-12, R-502), whose U.S. production ended on January 1, 1996. Class II ozone-depleting substances are the HCFCs (R-22, R-123), being phased out on a schedule that ends in 2030; new R-22 production already stopped in 2020.
HFCs (R-410A, R-134a, R-404A) are not ozone-depleting substances at all - they contain no chlorine - but their high GWP places them under the AIM Act phasedown. HFOs such as R-1234yf and R-1233zd are the newest family, with both near-zero ODP and very low GWP.
The Numbers and Dates Worth a Last-Minute Drill
A handful of figures show up again and again. Lock these in: 80% maximum cylinder liquid fill, 3 years for sales records, 30 days to repair a threshold-exceeding leak, 50 lbs (ozone-depleting) or 15 lbs (HFC, Part 84) as the leak-repair size triggers, 100,000 ozone molecules destroyed per chlorine atom, and 85% HFC reduction by 2036. On the date side, remember 1992 (CFC/HCFC venting ban), 1995 (HFC venting ban), 1996 (CFC production end), 2020 (R-22 production end), 2030 (HCFC phaseout complete), and 2036 (AIM Act 85% target). Treating these as flashcards in the final 48 hours is the highest-yield Core review you can do.
Worked example: A technician recovers R-134a from a walk-in cooler into a recovery cylinder, then on site runs it through a recycling machine that separates oil and filters moisture before charging it back into the same store's equipment. A coworker labels the cylinder "reclaimed." Is that correct? No. Because the refrigerant was only cleaned on site and returned to the same owner's system, this is recycling. "Reclaimed" would require reprocessing to AHRI 700 purity by an EPA-certified reclaimer, after which it could legally be resold to anyone. Choosing the right R-word is exactly the kind of distinction Core questions hinge on.
Match each Core term to the rule or value the exam expects you to recall.
Match each item on the left with the correct item on the right
Maximum cylinder liquid fill
Refrigerant sales record retention
HFC phasedown target by 2036 (AIM Act)
Element that destroys stratospheric ozone
Leak-repair deadline once the trigger rate is exceeded
Which statement about refrigerant families is correct for the Core exam?
HFCs have high ODP and zero GWP
HFCs have zero ODP but high GWP
CFCs have zero ODP and zero GWP
HCFCs contain no chlorine and have zero ODP
A technician removes refrigerant from a system, stores it in a cylinder, and does no cleaning or processing. This is best described as:
Reclamation
Recycling
Recovery
Retrofitting
Refrigerant sales records must be retained by the distributor for ___ years.
Type your answer below
Sections you finish are checked off in the contents.