Refrigerant Cheat Sheet: ODP, GWP & Safety Group (2026)
Complete refrigerant ODP GWP chart for EPA 608: 13 refrigerants, ASHRAE safety groups, chemical types. Plus 8 exam questions that always appear.
This refrigerant ODP GWP chart covers every refrigerant you need to know for the EPA 608 exam — organized by chemical type, ASHRAE safety group, ozone depletion potential, and global warming potential. Bookmark this refrigerant ODP GWP chart as your study reference: 13 refrigerants, their properties, which exam section tests them, and the 8 exam questions that always appear.
TL;DR — Refrigerant ODP GWP Chart
ODP = ozone damage (only CFC/HCFC have it — chlorine is the cause). GWP = global warming impact (CO₂ = 1, R-410A = 2,088). ASHRAE safety: A = lower toxicity, B = higher; 1 = non-flammable, 2L = mildly, 3 = highly. New A2L refrigerants (R-454B, R-32) have zero ODP and low GWP. This refrigerant ODP GWP chart has everything for the exam.
MASTER TABLE
13 Refrigerants You Must Know for EPA 608
| Refrigerant | Type | ASHRAE | GWP | ODP | Application | Section |
|---|---|---|---|---|---|---|
| R-11 | CFC | A1 | 4,750 | 1.00 | Centrifugal chillers (phased out) | III |
| R-12 | CFC | A1 | 10,900 | 1.00 | Old automotive AC (phased out) | — |
| R-22 | HCFC | A1 | 1,810 | 0.055 | Residential/commercial AC (phased out) | II |
| R-123 | HCFC | B1 | 77 | 0.02 | Centrifugal chillers | III |
| R-134a | HFC | A1 | 1,430 | 0 | Medium temp refrigeration / auto AC | II |
| R-404A | HFC blend | A1 | 3,922 | 0 | Commercial refrigeration | II |
| R-410A | HFC blend | A1 | 2,088 | 0 | Residential AC (phasing down) | II |
| R-454B | HFO/HFC | A2L | 466 | 0 | R-410A residential replacement | II |
| R-32 | HFC | A2L | 675 | 0 | Residential AC (global) | II |
| R-600a | HC | A3 | 3 | 0 | Household refrigerators | I |
| R-290 | HC | A3 | 3 | 0 | Small commercial refrigeration | I |
| R-717 | Natural | B2L | 0 | 0 | Industrial refrigeration (ammonia) | — |
| R-744 | Natural | A1 | 1 | 0 | CO₂ — transcritical / cascade | — |
* Section = which EPA 608 exam section covers this refrigerant. A2L highlighted = new for 2026.
ODP vs GWP: What Is the Difference?
The two most important columns in any refrigerant ODP GWP chart measure completely different environmental impacts. Understanding the difference is critical for the EPA 608 Core section — and it is one of the most frequently missed exam topics.
KEY CONCEPTS
ODP vs GWP: What's the Difference?
Ozone Depletion Potential
- • Measures ozone layer damage
- • Reference: R-11 = 1.0 (worst)
- • Only CFC and HCFC have ODP
- • HFC, HFO, HC = ODP 0 (no chlorine)
- • Regulated by: Montreal Protocol
Global Warming Potential
- • Measures how much heat the gas traps
- • Reference: CO₂ = 1
- • R-410A = 2,088× worse than CO₂
- • New A2L have much lower GWP
- • Regulated by: AIM Act (2020)
The key exam fact from this refrigerant ODP GWP chart: R-22 has both ODP and high GWP. R-410A has zero ODP but even higher GWP than R-22. The new A2L refrigerants solve both problems — zero ODP and dramatically lower GWP. This progression (CFC → HCFC → HFC → A2L) is the story of refrigerant evolution.
ASHRAE Safety Group Classification
Beyond ODP and GWP, the refrigerant ODP GWP chart includes ASHRAE Standard 34 safety classifications. The EPA 608 exam tests whether you can read this classification system — specifically the difference between A1 (safe, non-flammable), A2L (mildly flammable), and A3 (highly flammable).
ASHRAE 34 CLASSIFICATION
Refrigerant Safety Groups Explained
Toxicity: Lower
Flammability: Non-flammable
R-22, R-134a, R-410A, R-744
Toxicity: Lower
Flammability: Mildly flammable
R-32, R-454B, R-1234yf
Toxicity: Lower
Flammability: Flammable
R-152a, R-143a
Toxicity: Lower
Flammability: Highly flammable
R-290, R-600a, R-1270
Toxicity: Higher
Flammability: Non-flammable
R-123
Toxicity: Higher
Flammability: Mildly flammable
R-717 (ammonia)
How to read: Letter = toxicity (A=lower, B=higher). Number = flammability (1=none, 2L=mild, 2=yes, 3=high).
Refrigerant Types: CFC, HCFC, HFC, HFO, HC
The "Type" column in our refrigerant ODP GWP chart groups refrigerants by chemical family. This is fundamental EPA 608 exam knowledge:
- CFC (Chlorofluorocarbon) — Contains chlorine, fluorine, carbon. Highest ODP. Fully phased out. Examples: R-11, R-12.
- HCFC (Hydrochlorofluorocarbon) — Contains hydrogen, chlorine, fluorine, carbon. Lower ODP than CFC but still damages ozone. Phased out (R-22 banned 2020). Examples: R-22, R-123.
- HFC (Hydrofluorocarbon) — No chlorine = zero ODP. But high GWP. Being phased down under AIM Act. Examples: R-134a, R-410A.
- HFO (Hydrofluoroolefin) — Zero ODP, ultra-low GWP. The newest generation. Examples: R-1234yf (GWP under 1).
- HC (Hydrocarbon) — Natural refrigerants. Zero ODP, near-zero GWP. Highly flammable (A3). Examples: R-290 (propane), R-600a (isobutane).
The exam trick: if a refrigerant contains chlorine, it has ODP. If it does not contain chlorine (HFC, HFO, HC), ODP is zero. This rule applies to every entry in the refrigerant ODP GWP chart.
8 Refrigerant Questions That Always Appear on EPA 608
Every value in this refrigerant ODP GWP chart is a potential exam question. But these 8 appear on virtually every EPA 608 exam:
EXAM QUESTIONS
8 Refrigerant Questions That Always Appear on EPA 608
Which CFC has the highest ODP?
→ R-11 (ODP = 1.00)
Which refrigerant has the highest GWP?
→ R-12 (GWP = 10,900)
What element destroys the ozone?
→ Chlorine (in CFC and HCFC)
Does R-410A damage the ozone?
→ No — ODP 0, it's an HFC (no chlorine)
What appliance uses R-600a?
→ Household refrigerators (isobutane)
What is R-123's safety group?
→ B1 — higher toxicity, non-flammable
Does R-717 need a machinery room detector?
→ No if ventilation runs continuously
What is R-454B's GWP?
→ 466 (A2L — R-410A replacement)
Print our free refrigerant cheat sheet for a one-page version of this refrigerant ODP GWP chart. Then test yourself with our flashcards and practice test.
How to Use This Chart for Exam Prep
Do not try to memorize every number in this refrigerant ODP GWP chart. Instead, focus on patterns:
- Chlorine = ODP — If the name has "chloro" (CFC, HCFC), it depletes ozone
- CFC worst, then HCFC, then zero — ODP decreases as chlorine content decreases
- GWP has no simple pattern — Memorize the key values: R-410A = 2,088, R-454B = 466, R-32 = 675
- Safety group letter = toxicity, number = flammability — A is safe, B is toxic; 1 is no flame, 3 is high
- All A2L are new — If you see A2L on the exam, think R-454B, R-32, or R-1234yf
Frequently Asked Questions
What is ODP in refrigerants?
ODP (Ozone Depletion Potential) measures how much a refrigerant damages the stratospheric ozone layer. The reference is R-11 with ODP = 1.0. Only CFC and HCFC refrigerants have ODP because they contain chlorine. All HFC, HFO, and HC refrigerants in this refrigerant ODP GWP chart have ODP of zero.
What is GWP in refrigerants?
GWP (Global Warming Potential) measures how much heat a refrigerant traps in the atmosphere compared to CO₂ (GWP = 1). R-410A has a GWP of 2,088, meaning it traps 2,088 times more heat than the same amount of CO₂. The AIM Act targets refrigerants with GWP above 700 for phasedown.
Which refrigerant has the highest ODP?
R-11 (CFC) has the highest ODP at 1.00 — it is the reference standard. R-12 also has ODP of 1.00. Among refrigerants still in use for servicing, R-22 (HCFC) has an ODP of 0.055. Check the refrigerant ODP GWP chart above for all values.
What does A2L mean for refrigerants?
A2L is an ASHRAE Standard 34 safety classification meaning lower toxicity (A) and mildly flammable (2L). The "2L" indicates a burning velocity under 10 cm/s. A2L refrigerants like R-454B and R-32 are replacing R-410A in new HVAC systems. Your EPA 608 certification covers A2L.
What is the difference between ODP and GWP?
ODP measures ozone layer damage (caused by chlorine). GWP measures global warming contribution (caused by heat trapping). A refrigerant can have high GWP but zero ODP (like R-410A — no ozone damage but significant warming). This refrigerant ODP GWP chart shows both values side by side for easy comparison.
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Download the One-Page Cheat Sheet
This refrigerant ODP GWP chart condensed into one printable page — plus leak rates, recovery rules, and key numbers. Study it the night before your exam.