Core: Required for every type

Study guide

License Method EPA 608 prep. This guide was checked against the eCFR (40 CFR Part 82 Subpart F, Part 84, and 40 CFR 19.4) as of October 2026. Rules that changed recently are marked NEW or CHANGED. Items labeled Field practice come from EPA's test topics or normal shop practice, not regulation text.

What Core covers

Every certification (Type I, II, III, or Universal) requires passing Core. It covers what applies to all equipment: ozone and climate science, the laws, the Subpart F rules, the three Rs, recovery and evacuation, leak detection, safety, cylinders, and shipping. (Appendix D, section d)

Ozone depletion and climate

• The stratospheric ozone layer absorbs UV-B radiation. Ground-level ozone (smog) is a separate problem.
• Chlorine is what destroys ozone. CFCs and HCFCs drift into the stratosphere, where UV light breaks them apart and frees chlorine atoms. Each chlorine atom acts as a catalyst: it destroys an ozone molecule and is freed to destroy more, so one atom can destroy thousands.
• More UV-B means more skin cancer and cataracts and damage to crops and aquatic life.
• Ozone depletion potential (ODP) is measured against CFC-11 = 1.0. Global warming potential (GWP) is measured against CO2 = 1.
• How the refrigerant families rank on ODP:
  • CFCs (chlorine, fluorine, carbon), e.g. R-11, R-12, R-502: highest ODP.
  • HCFCs (with hydrogen), e.g. R-22, R-123: lower ODP, because the hydrogen makes them break down sooner in the lower atmosphere.
  • HFCs (no chlorine), e.g. R-134a, R-410A, R-32: zero ODP, but many have high GWP. That is why they are regulated today.
  • HFOs, e.g. R-1234yf, R-1234ze: very low GWP.

The laws: Clean Air Act and Montreal Protocol

• Montreal Protocol (1987): the treaty phasing out production of ozone-depleting substances (ODS). The Kigali Amendment added an HFC phasedown.
• Clean Air Act (CAA) Title VI: Section 608 covers stationary refrigeration and AC (this certification). Section 609 covers motor vehicle AC. Section 612 is SNAP, which lists acceptable substitutes.
• AIM Act (2020): directs EPA to phase down U.S. HFC production and consumption by 85% by 2036. It is a separate program from Section 608 (40 CFR Part 84).

Existing R-22 systems can still use recovered or reclaimed R-22.

Section 608 rules

Venting prohibition (82.154(a))

• You may not knowingly vent refrigerant while maintaining, servicing, repairing, or disposing of an appliance. The ban covers CFCs, HCFCs, and non-exempt substitutes such as HFCs and HFOs.
• Releasing refrigerant after you recover it is also a violation. (82.154(a)(3))
• Exempt in any application: CO2, nitrogen, and water. Ammonia is exempt in commercial and industrial process refrigeration and in absorption units. Certain hydrocarbons are exempt in specific end uses, such as R-600a and R-290 in household refrigerators. (82.154(a)(1)) Everything else is non-exempt. R-32 and R-454B (A2Ls) are not exempt.
• Leaks during normal operation aren't venting violations, though leak repair may apply to large ODS systems. (EPA venting guidance)

De minimis releases (82.154(a)(2))

Small releases during a good-faith attempt to recover refrigerant are not violations. They qualify only when the required practices are followed, certified recovery equipment is used, technician certification rules are met, and reclamation rules are followed. The typical example is the small amount lost when connecting and disconnecting hoses. Skipping recovery is never de minimis.

Nitrogen holding charges and leak-test gas

• Nitrogen alone: nitrogen is exempt in any application. Releasing a dry-nitrogen holding charge after the refrigerant was properly recovered is legal. (82.154(a)(1)(ii); 2016 rule preamble)
• Nitrogen with a trace of refrigerant: EPA's archived fact sheet Complying with the Section 608 Refrigerant Recycling Rule says nitrogen mixed with a trace of HCFC-22, used as a holding charge or leak-test gas, may be released, because the HCFC-22 is not being used as a refrigerant. The system must first be evacuated to the required level. ⚠️ Flag: EPA's current venting page does not repeat this guidance. Confirm it with your certifying organization's materials. The safest field practice is to leak test with nitrogen alone.
• Not a loophole: adding nitrogen to charged R-410A and venting the mix is a violation.

Covered appliances and key definitions (82.152)

• Appliances are classed by liquid-phase saturation pressure at 104 °F:

• A small appliance is fully manufactured, charged, and hermetically sealed in a factory with 5 lb or less of refrigerant.
• Opening an appliance is any service that would release refrigerant. Connecting and disconnecting hoses and gauges is not "opening," but it is still technician work that requires certification.
• Self-contained recovery equipment has its own means (usually a compressor) to remove refrigerant. System-dependent equipment uses the appliance's compressor or pressure. System-dependent equipment can't be used on systems over 15 lb unless it is a permanently attached pump-out unit. (82.156(e))
• Recovery and recycling equipment made on or after Nov 15, 1993 must be certified by an EPA-approved testing organization (third-party certification). (82.158(a), (d))

Refrigerant management updates

• CHANGED (2016 rule): sales restriction, recovery, certification, and disposal rules extended to HFCs and other non-exempt substitutes, mostly from Jan 1, 2018. (Venting substitutes was already banned by the CAA since 1995.)
• CHANGED (2020 rule, effective Apr 10, 2020): 608 leak repair, inspection, and related records now apply only to appliances with 50 lb or more of ODS. Everything else still applies to HFCs. (82.157(a))

Section 608 leak repair (ODS appliances only)

These rules apply to appliances with 50 lb or more of a CFC or HCFC refrigerant. (82.157)

• Repair within 30 days (120 days if an industrial process shutdown is needed). (82.157(d))
• An appliance that leaks 125% or more of its full charge in a calendar year must be reported to EPA by March 1 of the next year. (82.157(j))
• A leak inspection has to find where a leak is. Methods include ultrasonic tests, bubble tests, gas-imaging cameras, or a properly maintained electronic detector. Pressure-decay tests, sight glasses, and receiver levels can show that a system is leaking, but not where, so they must be paired with a locating method. (82.152, "Leak inspection")

Substitutes, SNAP, oils, and blends

• SNAP (CAA 612; 40 CFR 82 Subpart G) lists acceptable substitutes and their use conditions.
• There are no true "drop-in" replacements. A conversion (retrofit) may need different oil, seals, filter-driers, or settings.
• Oils: HFCs such as R-134a and R-410A use POE (polyolester) oil. CFCs and HCFCs traditionally use mineral or alkylbenzene oil. Mixing incompatible refrigerants and oils causes problems.
• Blends:
  • Zeotropic blends (400 series, such as R-410A, R-407C, R-404A) have temperature glide and can fractionate, meaning their components leak at different rates and the mix changes. Field practice: charge zeotropes as liquid.
  • Azeotropic blends (500 series, such as R-500, R-502) behave like a single refrigerant.
• A2L refrigerants (ASHRAE 34: lower toxicity, mild flammability), such as R-32 and R-454B, are common in new AC. Recovery equipment for flammables is certified under Appendix B4. (82.158(d)(3))

NEW: AIM Act leak repair (separate from Section 608)

NEW (Jan 1, 2026): 40 CFR 84.106 adds HFC leak repair for appliances with 15 lb or more of an HFC, or a substitute with GWP above 53. It excludes residential and light-commercial AC and heat pumps, and uses the same 20/30/10% leak rates. This is a separate rule from Section 608. You need it on the job, but testing programs may not test it yet. EPA proposed changes to this rule in 2026 (exempting transport refrigeration units), so check its current status before relying on details.

The three Rs (82.152, 82.154(d), 82.164)

• Recovered refrigerant may go back into the same appliance or another one owned by the same person without reclaiming. MVAC and MVAC-like appliances are the exception. (82.156(h))
• Used refrigerant sold to a new owner must be reclaimed. (82.154(d); for HFCs also 84.104(a))

Recovery techniques

• Field practice: never mix refrigerants in one recovery cylinder. Mixtures often can't be separated and may have to be destroyed.
• Field practice: recovery is faster with short, large-diameter hoses, valve cores removed, liquid first, a cool recovery cylinder, and a larger machine.
• Before opening a system, evacuate it to the required level and verify that level has been reached. Type II and III cover the details. For leaky systems, isolate the leaking part and evacuate as low as you can without contaminating the refrigerant, never above 0 psig. Before an oil change, the system must be at 5 psig or lower. (82.156(a))

Dehydration and evacuation

• At the end of service, evacuate with a vacuum pump to remove air and moisture before charging. Moisture forms acids and sludge, and air (a non-condensable) raises head pressure.
• Field practice: use a micron gauge and the manufacturer's evacuation target; never run a hermetic compressor under deep vacuum.
• Refrigerant absorbs heat in the evaporator (liquid to vapor) and rejects it in the condenser. psia = psig + 14.7.
• Field practice: on a manifold gauge set, the blue hose is the low side (compound gauge), red is the high side, and yellow is the utility or charging hose.

Leak detection

• Field practice: pressurize with dry nitrogen alone, through a pressure regulator and relief valve. EPA's test topics rank nitrogen alone as the best leak-test gas. Nitrogen with a trace of HCFC-22 comes next, for when an electronic detector is needed.
• Never use oxygen or compressed air. Oxygen can explode with oil under pressure, and air adds moisture.
• Field practice: look for oily residue at joints, and leak test before charging.

Safety

• Oxygen deprivation: refrigerant vapor is heavier than air and displaces oxygen in enclosed spaces and low areas. Ventilate.
• Cardiac effects: high concentrations can cause irregular heartbeat. Frostbite: liquid refrigerant freezes skin and eyes.
• Decomposition: an open flame or hot surface breaks refrigerants down into toxic, corrosive gases, including phosgene (from chlorinated refrigerants) and acids.
• PPE: at minimum, safety glasses or goggles and gloves. Use SCBA in extreme cases, such as a large leak in an enclosed space.
• Field practice for flammables (A2L and A3): no ignition sources, rated tools, and ventilation.

Recovery cylinders and shipping

• Recovery (reusable) cylinders must be DOT-approved. They are identified by a gray body and yellow top. (EPA Core test topics)
• Field practice: fill a recovery cylinder to no more than 80% of capacity. Liquid expands as it warms, and an overfilled cylinder can rupture.
• Disposable cylinders (DOT-39) must never be refilled. Recover any leftover refrigerant before disposal.
• Field practice: before filling, confirm the cylinder is DOT-approved and within its stamped requalification date. DOT intervals vary by cylinder spec (49 CFR 180.209).
• Never heat a cylinder with an open flame.
• Shipping: label cylinders with the refrigerant's name and the DOT hazard classification. (EPA Core test topics; 49 CFR Part 172) Field practice: most fluorocarbon refrigerants ship as Division 2.2 (non-flammable gas). Flammables, including A2Ls, use 2.1. Confirm with your shipper.

Certification, sales, and records

• Who needs certification: anyone whose work could release refrigerant (attaching gauges, adding or removing refrigerant, cutting lines). Registered apprentices may work closely and continually supervised, for up to 2 years. (82.152; 82.161(a)(2))
• Certification does not expire. EPA can revoke or suspend it for violations. (82.161(a)(3))
• Keep a copy of your certificate at your place of business until 3 years after you stop working as a technician. (82.161(a)(4))
• Sales restriction: CFCs, HCFCs, and (since Jan 1, 2018) HFCs and other non-exempt substitutes may be sold only to certified technicians or employers who show proof of one, plus a few listed buyers. Exception: car AC cans of 2 lb or less with a self-sealing valve. Sellers keep invoices 3 years. (82.154(c))
• Disposal records: technicians disposing of appliances with more than 5 and less than 50 lb of refrigerant keep records for 3 years. Final processors of small appliances keep signed statements for 3 years. (82.156(a)(3); 82.155)

Penalties

The maximum CAA civil penalty is $124,426 per day per violation for penalties assessed on or after Jan 8, 2025 (CAA 113(b); 40 CFR 19.4, Table 1). The statute set $25,000; EPA adjusts it for inflation, so re-check 19.4 yearly.

The Core test

• 25 questions. You need 70%, or 18 of 25 correct. (Appendix D; 82.161(c))
• Core is closed-book and proctored when taken toward Type II, Type III, or Universal. An open-book Core taken with a mail-in Type I can't be used toward Universal. (Appendix D; EPA certification requirements page)
• Time limits vary by certifying organization. EPA doesn't set a national time limit.

Common traps

• "HFCs have zero ODP, so they can be vented." They can't. They are non-exempt substitutes.
• "608 leak repair covers my R-410A system." It doesn't. Section 608 leak repair is ODS-only (50 lb or more). The AIM Act 15-lb rule is separate from Section 608. You need it on the job, but testing programs may not test it yet.
• "Adding nitrogen makes it OK to vent." Only nitrogen alone, or a trace-gas mix after proper evacuation (flagged above), can be released.
• Mixing up recover, recycle, and reclaim. Only reclaim meets AHRI 700, and only reclaimed refrigerant goes to a new owner.
• Thinking R-22 is banned from use. Only new production ended in 2020.
• Using oxygen or shop air for a leak test.
• Mixing up the numbers: 5 lb small appliance, 15 lb system-dependent limit (and AIM leak repair), 50 lb 608 ODS leak repair.

Quick review

• Chlorine destroys ozone catalytically; ODP ranks CFC > HCFC > HFC (0)
• Montreal Protocol, CAA 608/609/612 (SNAP), AIM Act; CFCs ended 1996, R-22 2020, HCFCs 2030
• Venting ban covers CFCs, HCFCs, and HFCs. Exempt: CO2, N2, water, plus listed uses. Releasing recovered refrigerant is a violation
• De minimis requires good-faith recovery with certified equipment
• Nitrogen holding charge is legal; trace HCFC-22 only after evacuation (flagged)
• 608 leak repair: ODS, 50 lb or more; 20/30/10%; 30 days; 125% report by Mar 1
• Recover, recycle, reclaim (AHRI 700, certified reclaimer)
• Never mix refrigerants; evacuate to remove air and moisture; leak test with nitrogen, never oxygen or air
• Oxygen deprivation, cardiac effects, frostbite, phosgene; goggles and gloves; SCBA in extremes
• Gray/yellow recovery cylinders, 80% fill, never refill disposables, label with name and DOT class
• Sales restricted (HFCs since 2018); records kept 3 years; certification never expires
• $124,426 per day per violation (re-check yearly); 25 questions, 18 to pass; time limits vary

Rapid-fire numbers to memorize