EPA 608 Core Exam Study Guide [2025]

The EPA 608 Core exam is required for all certification types and covers fundamental refrigerant handling regulations, environmental science, and safety procedures. This comprehensive guide breaks down every Core section topic including the Clean Air Act, Montreal Protocol, ozone depletion science, refrigerant classifications, and recovery requirements. Master these fundamentals to pass your Core section and move forward with Type 1, 2, 3, or Universal certification.

What Is the EPA 608 Core Exam?

The Core section tests your knowledge of federal refrigerant regulations and environmental science that apply to all HVAC/R work. Unlike Type 1, 2, and 3 sections that focus on specific equipment categories, Core covers universal knowledge every certified technician must know regardless of what systems they work on.

You must pass the Core exam to earn any EPA 608 certification. If you're pursuing Universal certification, you'll take Core plus all three Type exams in one sitting. For individual Type certifications (Type 1, 2, or 3 only), you'll take Core plus your chosen Type section.

The Core exam emphasizes regulatory compliance and environmental protection. Expect questions about Clean Air Act requirements, Montreal Protocol dates, refrigerant characteristics, ODP and GWP values, recovery equipment standards, and technician responsibilities under federal law.

Clean Air Act Section 608

Overview of Section 608

Section 608 of the Clean Air Act, established in 1990, regulates refrigerant handling to protect stratospheric ozone and reduce greenhouse gas emissions. This section requires technician certification, mandates proper refrigerant recovery, prohibits intentional venting of most refrigerants, and sets equipment standards for recovery and recycling.

Key Section 608 requirements you must know:

• Certification Requirement: Anyone who maintains, services, repairs, or disposes of appliances containing refrigerant must be EPA 608 certified
• Venting Prohibition: Knowingly releasing CFC, HCFC, and HFC refrigerants during maintenance, service, repair, or disposal is illegal
• Recovery Mandate: Technicians must recover refrigerant to EPA-required levels before opening or disposing of appliances
• Leak Repair Requirements: Commercial and industrial equipment with leaks above threshold rates must be repaired within specified timeframes
• Record Keeping: Facilities must maintain service records showing refrigerant added, recovered, and leak rates

Why Section 608 Exists

Before 1990, refrigerant handling was largely unregulated. Technicians routinely vented refrigerants to the atmosphere when servicing equipment, contributing to ozone layer depletion and climate change. Section 608 established the regulatory framework to phase out ozone-depleting substances and minimize refrigerant emissions.

The law evolved from the Montreal Protocol, an international treaty signed in 1987 to protect the ozone layer. The United States implemented Montreal Protocol requirements through Clean Air Act amendments, creating the certification and recovery requirements technicians follow today.

Montreal Protocol & Key Dates

Understanding the Montreal Protocol

The Montreal Protocol on Substances that Deplete the Ozone Layer is the most successful international environmental treaty in history. Signed September 16, 1987, it established schedules to phase out production and consumption of ozone-depleting substances (ODS) including CFCs, HCFCs, and halons.

Every country in the world ratified the Montreal Protocol, making it the first universally ratified UN treaty. The protocol uses a phased approach, setting different deadlines for developed and developing nations to phase out various refrigerants based on their Ozone Depletion Potential (ODP).

Refrigerant Phase-Out Timeline

CFCs (Chlorofluorocarbons): Production banned January 1, 1996 for developed countries. These refrigerants (R-12, R-502, R-11, R-113, R-114, R-115) have the highest ozone depletion potential and were the first targeted for elimination.

HCFCs (Hydrochlorofluorocarbons): Being phased out gradually. R-22 production and import stopped January 1, 2020 in the United States. However, reclaimed and recycled R-22 can still be used for service. Complete HCFC phaseout scheduled for 2030.

HFCs (Hydrofluorocarbons): Do not deplete ozone (ODP = 0) but have high global warming potential. The 2016 Kigali Amendment to Montreal Protocol phases down HFC production and use, with developed countries reducing HFC consumption 85% by 2036.

Ozone Depletion Science

How Ozone Depletion Works

Stratospheric ozone (O₃) forms a protective layer 10-50 kilometers above Earth's surface, absorbing 97-99% of harmful ultraviolet (UV-B) radiation from the sun. Ozone molecules consist of three oxygen atoms bonded together, creating a shield that makes life on Earth possible.

When CFCs and HCFCs reach the stratosphere, ultraviolet radiation breaks apart these molecules, releasing chlorine atoms. One chlorine atom can destroy over 100,000 ozone molecules through a catalytic chain reaction before being removed from the stratosphere. Bromine from halons is even more destructive, with each bromine atom destroying 10 times more ozone than chlorine.

The ozone depletion cycle:

1. Refrigerant released at ground level rises slowly to stratosphere (takes 2-5 years)
2. UV radiation breaks chemical bonds, releasing chlorine or bromine atoms
3. Chlorine reacts with ozone (O₃), creating chlorine monoxide (ClO) and oxygen (O₂)
4. ClO releases chlorine atom, which remains free to destroy more ozone molecules
5. Cycle continues for 50-100 years until chlorine is removed from atmosphere

Ozone Depletion Potential (ODP)

ODP measures a refrigerant's ability to destroy stratospheric ozone compared to R-11 (CFC-11), which has an assigned ODP of 1.0. Higher ODP values indicate greater ozone destruction potential.

Refrigerant Type	Example	ODP Range	Status
CFCs	R-12, R-502	0.6 - 1.0	Production banned
HCFCs	R-22, R-123	0.02 - 0.11	Being phased out
HFCs	R-134a, R-410A	0	Replacing HCFCs
Natural	R-717 (ammonia)	0	Traditional alternative

Global Warming Potential (GWP)

GWP measures a refrigerant's heat-trapping ability compared to carbon dioxide (CO₂), which has a GWP of 1. GWP calculations typically use a 100-year time horizon to assess long-term climate impact.

While HFCs don't deplete ozone (ODP = 0), many have extremely high global warming potentials. For example, R-404A has a GWP of 3,922, meaning one pound of R-404A traps 3,922 times more heat than one pound of CO₂ over 100 years. This is why HFCs are now being phased down through the Kigali Amendment.

Refrigerant Classifications

Safety Group Classifications

ASHRAE Standard 34 classifies refrigerants by toxicity and flammability using a two-character code:

Toxicity (letters):

• Class A: Lower toxicity (safe exposure limit ≥ 400 ppm)
• Class B: Higher toxicity (safe exposure limit < 400 ppm)

Flammability (numbers):

• Class 1: No flame propagation
• Class 2: Lower flammability
• Class 2L: Mildly flammable (lower burning velocity)
• Class 3: Higher flammability

Common safety classifications: R-134a (A1), R-410A (A1), R-32 (A2L), R-290/Propane (A3), R-717/Ammonia (B2L)

High-Pressure vs Low-Pressure Refrigerants

High-pressure refrigerants have boiling points below 50°F at atmospheric pressure (14.7 psia). These refrigerants operate above atmospheric pressure during both evaporator and condenser operation at typical temperatures. Examples include R-22, R-410A, R-134a, R-404A, and R-407C.

Low-pressure refrigerants have boiling points above 50°F at atmospheric pressure. The evaporator operates below atmospheric pressure (vacuum), creating air leak risks. R-123 is the most common low-pressure refrigerant, used in centrifugal chillers (Type 3 equipment).

Recovery Requirements & Procedures

Required Recovery Levels

EPA mandates specific vacuum levels that must be achieved before opening or disposing of refrigerant-containing appliances. Required levels vary by equipment type and recovery method:

Equipment Type	Recovery Method	Required Vacuum
Small appliances (< 5 lbs)	Any method	0 psig or 80% recovery
High-pressure (HCFC, CFC)	Using recovery equipment	10 inches Hg vacuum
High-pressure (HFC, HFO)	Using recovery equipment	0 psig
Very high-pressure (R-410A, R-404A)	Using recovery equipment	0 psig
Low-pressure (R-123)	Using recovery equipment	25 mm Hg absolute

Recovery Equipment Certification

All recovery and recycling equipment must be tested and certified by an EPA-approved testing organization (currently AHRI). Certification ensures equipment meets SAE J2810 and similar industry standards for recovery efficiency and refrigerant purity.

Equipment categories:

• Recovery-only: Removes refrigerant but doesn't clean it for reuse
• Recovery/Recycling: Removes refrigerant and cleans it to reusable purity through oil separation and filtration
• Reclaim: Industrial-scale process returning refrigerant to AHRI 700 virgin specification

System-Dependent vs Self-Contained Recovery

System-dependent recovery uses the appliance's own compressor to push refrigerant into a recovery cylinder. This method is slower, less efficient, and cannot achieve required vacuum levels for most equipment. It's acceptable only for disposing of small appliances containing less than 15 pounds of refrigerant.

Self-contained recovery uses an external recovery machine with its own compressor to pull refrigerant from the appliance. This is the standard method for all professional service work, achieving required vacuum levels efficiently and safely.

Refrigerant Cylinder Colors & Safety

Cylinder Color Codes

While refrigerant cylinder colors are not federally mandated, industry standards help identify contents. However, never rely solely on color — always verify cylinder contents by reading the label.

Common cylinder colors: Gray top with white body (recovered refrigerant), yellow (for reclaimed/recycled refrigerant), manufacturer-specific colors for virgin refrigerants (R-22 green, R-410A rose/pink, R-134a light blue).

Recovery cylinders must be specifically designed and rated for refrigerant recovery. Never use disposable refrigerant cylinders for recovery — they're designed for one-way use only and cannot safely handle recovered refrigerant.

Cylinder Filling Limits

Recovery cylinders must never be filled above 80% of their gross weight rating to allow for liquid expansion. Overfilling creates dangerous pressure buildup if temperature rises, potentially causing cylinder rupture.

Safe filling procedure: Weigh empty cylinder (tare weight), calculate 80% fill capacity, weigh during filling, stop when reaching 80% capacity. Most recovery equipment includes automatic shutoff at safe fill levels.

Technician Responsibilities

What Certification Allows

EPA 608 certification authorizes you to purchase refrigerant and perform maintenance, service, and repair on refrigerant-containing appliances matching your certification type. Core certification alone doesn't authorize refrigerant purchase — you need Core plus at least one Type certification.

Type 1: Small appliances (5 lbs or less refrigerant)

Type 2: High-pressure appliances except small appliances and MVACs

Type 3: Low-pressure appliances (centrifugal chillers)

Universal: All types of equipment

Required Documentation

Facilities must maintain records of refrigerant purchases, quantities added during service, amounts recovered, and leak rates for applicable equipment. These records must be kept for at least 3 years and made available to EPA inspectors upon request.

Technicians must carry proof of EPA 608 certification when purchasing refrigerant or performing service work. Some jurisdictions require additional state or local HVAC licensing beyond federal EPA certification.

Penalties for Violations

Clean Air Act violations carry significant penalties. Individuals can be fined up to $44,539 per day per violation. Companies can face fines up to $88,957 per day per violation. Criminal penalties include fines up to $1 million and imprisonment up to 5 years for knowing violations.

Common violations include venting refrigerant, falsifying certification, using uncertified recovery equipment, failing to recover to required levels, and servicing equipment without proper certification.

Core Exam Study Tips

Focus on High-Frequency Topics

Core exam questions heavily emphasize Montreal Protocol dates, recovery requirements, ODP/GWP concepts, and Clean Air Act regulations. Memorize the 1987, 1990, 1995, 1996, and 2020 dates. Understand required vacuum levels for different equipment types. Know the difference between CFCs, HCFCs, and HFCs.

Use Mnemonics for Dates

"Montreal Protocol '87, Clean Act '90, CFC ban '95, Cert required '96" — Create memory aids for critical dates. Link dates to major events: Montreal Protocol 1987 (before Clean Air Act), CFC ban 1995 (after Montreal), mandatory certification 1996 (latest requirement).

Understand Concepts, Don't Just Memorize

Questions often test understanding rather than pure memorization. Know why CFCs deplete ozone (chlorine catalyst), how the Montreal Protocol phased out refrigerants (ODP-based timeline), and what drives recovery requirements (environmental protection + regulatory compliance).

Take Practice Tests Repeatedly

Practice tests reveal knowledge gaps and familiarize you with question formats. Take the Core practice test multiple times, reviewing explanations for missed questions. Focus extra study on consistently missed topics.

Next Steps After Core

Passing the Core exam is your foundation for EPA 608 certification, but Core alone doesn't authorize refrigerant purchase. You must pass at least one Type exam to earn a certification credential.

Choose your path:

• Universal Certification: Study Universal Guide and prepare for all Type sections
• Type 1 Only: Review Type 1 Guide for small appliances
• Type 2 Only: Study Type 2 Guide for high-pressure systems
• Type 3 Only: Learn Type 3 Guide for low-pressure chillers

Most HVAC professionals pursue Universal certification to work on all equipment types without restrictions. If you're certain you'll only work on one category, a single Type certification may suffice initially — you can always test for additional Types later.