EPA 608 Core Study Guide
Every EPA Section 608 certification — Type I, Type II, Type III, and Universal — requires passing the Core section. Core is not tied to one kind of equipment. Instead, it tests the shared knowledge that every refrigerant technician needs: why refrigerants are regulated, how to handle them legally, and how to stay safe while doing it. If you only study one section thoroughly before exam day, make it this one, because Core mistakes cost you on every certification path.
This guide walks through the major Core topics in the order they tend to make sense, with the reasoning behind each rule. Memorizing answer letters works for a while, but Core questions often reword the same idea three different ways. Understanding the "why" is what gets you through the ones you have not seen before.
Why Refrigerants Are Regulated
The whole reason Section 608 exists is environmental. Older refrigerants — chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) — contain chlorine. When these refrigerants are released into the atmosphere, they eventually drift up to the stratosphere, where ultraviolet light breaks them apart and frees that chlorine. A single chlorine atom can destroy many ozone molecules in a chain reaction. The ozone layer matters because it absorbs harmful UV radiation, so thinning it has real consequences for health and the environment.
Two measurements come up constantly on the exam. Ozone Depletion Potential (ODP) compares how much a refrigerant damages the ozone layer relative to CFC-11. Global Warming Potential (GWP) compares how much it contributes to climate change relative to carbon dioxide. CFCs have the highest ODP, HCFCs are lower, and HFCs (hydrofluorocarbons) contain no chlorine and have an ODP of essentially zero — but many HFCs still have a high GWP, which is why they are now being phased down too. Knowing which family a refrigerant belongs to tells you most of what a Core question is testing.
The Venting Prohibition
The single most important Core rule: under Section 608, it is illegal to knowingly release (vent) regulated refrigerant into the atmosphere during the service, maintenance, repair, or disposal of appliances. This venting prohibition is the backbone of the whole program.
There are a few narrow exceptions you should recognize rather than memorize as loopholes. Small releases that happen during good-faith service practices — such as the tiny amount lost when properly connecting and disconnecting gauges or hoses — are not considered illegal venting. Releases of certain non-ozone-depleting, non-exempt substances may be treated differently, and nitrogen used for leak testing or purging is not a regulated refrigerant. But the safe default on the exam is simple: you do not vent refrigerant, you recover it.
Recovery, Recycling, and Reclaiming
These three terms get confused more than anything else on the Core exam, and questions deliberately use them as wrong answers for each other. Learn them as a sequence:
- Recovery means removing refrigerant from an appliance and storing it in an external container, without testing or processing it in any way. That is it — just getting it out and into a cylinder.
- Recycling means cleaning the refrigerant for reuse, typically by separating oil and passing it through filter-driers to reduce moisture and acidity. Recycling is usually done on site with the same equipment that recovered it. It does not certify the refrigerant to any purity standard.
- Reclaiming means reprocessing refrigerant to meet the strict ARI/AHRI 700 purity standard — the same specification as new refrigerant. Reclaiming requires laboratory-grade processing and chemical analysis, so it is done by certified reclaimers, not in the field. Only reclaimed refrigerant can generally be sold to a different owner.
A useful shortcut: recovery is removal, recycling is on-site cleanup for the same owner, and reclaiming is full reprocessing to like-new standard.
Recovery Equipment and Certification
Recovery and recycling equipment manufactured after a certain date must be certified by an EPA-approved testing organization to meet performance standards. The exam expects you to know that you cannot use just any pump — the equipment has to be certified for the job. Required recovery and evacuation levels depend on the appliance type and on whether the equipment was manufactured before or after a regulatory cutoff date, which is why those specific numbers are covered in the Type I, II, and III guides rather than here.
Refrigerant Cylinders and Handling
Recovered refrigerant goes into a recovery cylinder, not a disposable (one-time-use) cylinder. Recovery cylinders are reusable, DOT-approved pressure vessels, and they must be kept current on hydrostatic testing. Two safety rules show up again and again:
- Never fill a cylinder above 80 percent of capacity. Liquid refrigerant expands as it warms. A cylinder filled completely with liquid leaves no room for that expansion, and hydrostatic pressure can rupture it. The 80 percent rule leaves a vapor space for safety.
- Never mix refrigerants in the same recovery cylinder. A mixed cylinder of refrigerant cannot be reclaimed and usually has to be destroyed, which is expensive and wasteful. Use a separate, properly labeled cylinder for each refrigerant.
Disposable cylinders that once held new refrigerant should be fully emptied, their valves rendered useless, and then they may be recycled as scrap metal — you do not refill them.
Technician Safety
Core also tests personal safety, and these questions are easy points if you think them through. Refrigerant vapor is heavier than air and displaces oxygen, so a leak in an enclosed space can cause suffocation with no warning — this is why mechanical rooms need ventilation and oxygen sensors. Refrigerant should never be exposed to an open flame or very high heat, because it can decompose into toxic and corrosive products such as phosgene and hydrofluoric or hydrochloric acid.
When working with refrigerant, wear safety glasses and gloves. Liquid refrigerant contact with skin or eyes causes frostbite because it boils at very low temperatures. Self-contained breathing apparatus is the appropriate protection if you must enter an area with a large refrigerant concentration. Treat pressurized cylinders with respect: store them upright, secured, away from heat, and never apply a torch to a cylinder.
Sales, Recordkeeping, and Disposal
Regulated refrigerant may generally only be sold to certified technicians or to people buying it for a certified technician's use. Technicians and companies are expected to keep records of recovered, recycled, and reclaimed refrigerant, and certain appliances require documentation when refrigerant is added or removed. For appliance disposal, the final person in the disposal chain is responsible for making sure refrigerant has been recovered before the equipment is scrapped — which is why so many Type I questions involve recovering refrigerant from a unit headed for the landfill.
How to Study Core Effectively
Start with Core study mode in the app and read every explanation, not just the ones you miss. Once the vocabulary feels automatic, switch to smart practice so the app feeds you more of the questions you struggle with. Pay special attention to anything involving recovery versus recycling versus reclaiming, the venting rules, cylinder safety, and the ODP/GWP distinction — those four areas account for a large share of missed Core questions.
When a Core question feels tricky, slow down and ask: what is this really testing — a definition, a safety practice, or a legal requirement? Naming the category usually points you straight at the answer.
Keep Practicing
When you can move through Core study mode without second-guessing the terms, take a Core practice exam to confirm you can hold the information across a longer session. After Core, move on to the equipment type you need: the Type I guide, Type II guide, or Type III guide. For the big picture, see the EPA 608 exam overview.
Not affiliated with the EPA. For study practice only. EPA regulations change over time — always verify current rules with official EPA materials and your testing provider.