Types of Refrigerant: The Classes You Actually Need to Know

Refrigerants are classified three different ways at once. By chemistry — CFC, HCFC, HFC, HFO and natural. By the pressure of the appliance they run in — low, medium, high and very high, defined at 104 °F in 40 CFR 82.152. And by ASHRAE safety group — A1, A2L, B1 and the rest. All three are separate systems.

The reason this question is so muddled online is that a fourth numbering scheme sits on top of it. EPA 608 certification has a Type I, a Type II and a Type III, and people reasonably assume those describe kinds of refrigerant. They do not. There is no such thing as a "Type 3 refrigerant." Here is what each system actually sorts, and which one decides what you may legally touch.

What are the main types of refrigerant by chemistry?

This is the family tree, and it is organized around one atom: chlorine. Chlorine is what destroys stratospheric ozone, and the history of refrigerant regulation is the history of taking it out.

Family	Contains	Ozone depletion	Examples
CFC	Chlorine, fluorine, carbon	Highest — ODP around 1.0	R-11, R-12, R-502
HCFC	Adds hydrogen, so it breaks down lower in the atmosphere	Lower — R-22 is roughly 0.05	R-22, R-123
HFC	Hydrogen, fluorine, carbon — no chlorine	Zero, but high GWP	R-134a, R-410A, R-404A, R-32
HFO	Same atoms, with a carbon double bond	Zero ODP, very low GWP	R-1234yf, and the HFO content in R-454B
Natural	Not halocarbons at all	Zero ODP, negligible GWP	R-717 ammonia, R-744 CO₂, R-290 propane

Two ratios get confused constantly. ODP is measured against CFC-11, which is defined as 1.0. GWP is measured against carbon dioxide, defined as 1. They are unrelated scales. R-134a has an ODP of zero and a GWP in the region of 1,400 — harmless to ozone, and still tightly regulated, because of the second number.

That is why the phase-down of HFCs runs on a completely different legal track from the CFC and HCFC phase-outs. The old ones came out under Title VI of the Clean Air Act. HFCs are handled by the AIM Act of 2020, which cuts US production and consumption by 85% below baseline by 2036 (EPA).

What are "Type 1, Type 2 and Type 3 refrigerants"?

They do not exist. This is the single most common mix-up on the subject, and it is worth killing off cleanly.

Type I, Type II and Type III are certification sections for people. They describe which class of appliance a technician is certified to work on. They say nothing about the chemical in it. R-410A is not "a Type II refrigerant" — it is a refrigerant that happens to be used in high-pressure appliances, which are Type II work.

The sections and what they cover are set out in EPA 608 Type I, Type II and Type III explained. The short version: Type I is small appliances holding five pounds or less, Type II is high-pressure equipment, Type III is low-pressure equipment.

How does EPA actually classify refrigerants?

By the pressure the refrigerant sits at inside an appliance. Each class is stated as the saturation pressure of the liquid at 104 °F — roughly the condensing condition of an air-cooled machine on a hot day, which is when a system runs at its highest pressure.

Appliance class	Liquid saturation pressure at 104 °F	Examples	Certification
Low-pressure	Below 45 psia	R-11, R-113, R-123, R-245fa	Type III
Medium-pressure	45 to 170 psia	R-12, R-134a, R-500	Type II
High-pressure	170 to 355 psia	R-22, R-407C, R-410A	Type II
Very high-pressure	Above 355 psia	R-13, R-23, R-503, R-508B	Type II

Notice that Type II covers three of the four classes. Only low pressure is carved out, and it is carved out because low-pressure machines run in a vacuum at normal evaporator temperatures. Air and moisture leak in rather than refrigerant leaking out. That one fact generates nearly every Type III rule — purge units, non-condensable removal, and a recovery target stated in millimeters of mercury absolute instead of inches of vacuum.

What are the ASHRAE safety groups?

This is the third system, and it is the one that matters most in 2026 because of A2Ls. Toxicity and flammability are classified under ASHRAE Standard 34 as a letter plus a number.

	Lower toxicity (A)	Higher toxicity (B)
Class 3 — higher flammability	A3 — R-290 propane, R-600a isobutane	B3
Class 2 — lower flammability	A2	B2
Class 2L — mildly flammable, low burning velocity	A2L — R-32, R-454B, R-1234yf	B2L — R-717 ammonia
Class 1 — no flame propagation in air at test conditions	A1 — R-22, R-134a, R-410A, R-404A	B1 — R-123

The letter is toxicity: A is lower, B is higher. The number is flammability: 1 means no flame propagation under test conditions, 3 means highly flammable. 2L was added for refrigerants that will burn, but only sluggishly, needing a high concentration and a sustained ignition source.

Ammonia is the instructive case. It is B2L — higher toxicity and mildly flammable — which is why it is confined to industrial plants with trained operators rather than rooftop package units.

What is the difference between a single refrigerant and a blend?

The R-number tells you. Single compounds sit in the methane and ethane series — R-11, R-12, R-22, R-134a. Blends get the 400s and 500s, and the difference between those two ranges is the one with field consequences.

• R-400 series are zeotropic. The components have different boiling points, so the mixture's temperature rises across the evaporator at constant pressure. That spread is temperature glide.
• R-500 series are azeotropic. They behave as a single substance, boiling and condensing at one temperature for a given pressure.

Two rules follow, and both are tested. Charge a blend as a liquid — draw vapor off a zeotropic cylinder and you preferentially remove the lighter component, changing what is left behind and what goes in. And never top off a leaking blend system; after a leak the remaining charge is no longer the blend it started as, so you recover it all, repair, evacuate and weigh in a fresh charge. R-454B is a zeotropic blend, which is why it is fussier to charge than R-32 despite the lower GWP.

Which types of refrigerant can you buy with a 608 card?

All of them, for stationary work — that is what the card is for.

Under the refrigerant sales restriction, ozone-depleting substances and their substitutes may only be sold to a Section 608 certified technician or their employer, with written proof of employment. EPA states it directly: "Only Section 608 certified technicians can purchase refrigerants intended for use with stationary refrigeration and air-conditioning equipment" (EPA).

The practical point is that A2Ls carry no exemption. R-32 and R-454B are non-exempt substitutes, so the venting prohibition, technician certification, evacuation requirements and sales restriction apply to them exactly as they apply to R-410A. Nothing in Subpart F treats them differently. The one carve-out worth knowing is on the vehicle side: small cans of MVAC refrigerant holding two pounds or less, with self-sealing valves, may be sold to uncertified buyers.

What this means on the job

Sort out which system somebody is using before you act on what they tell you.

If a supplier or a spec sheet says "Type II," that is about your certification and the appliance, not the chemical. If it says "A2L," that is about flammability, and it changes your equipment: recovery machines manufactured or imported on or after January 1, 2017 are certified under Appendix B3 for non-flammable refrigerants or Appendix B4 for flammable refrigerants, and a unit rated only for A1 is not approved for A2L work. If it says "R-400 series," that is about glide, and it changes how you charge.

Where these genuinely intersect is the pressure class, because that is what decides your certification. And it is worth being precise about which rules bind you: charging a blend as a liquid is required practice with a regulatory consequence if you get it wrong and vent the difference, whereas pulling to 500 microns is good service discipline rather than a Section 608 evacuation requirement. Competitors blur that line constantly. Knowing which is which is what separates a technician who passes an inspection from one who merely passes the exam — and both are worth practicing against real questions before you sit down.

Frequently asked questions

What are the three types of refrigerants?

There is no authoritative three-way split, and the question usually comes from confusing refrigerants with EPA 608 Type I, II and III, which classify technicians and appliances rather than chemicals. If you want a three-way chemical split, the usual one is CFC, HCFC and HFC — with HFOs and natural refrigerants now added as a fourth and fifth family.

What are type 3 refrigerants?

Not a real category. Type III is an EPA 608 certification section covering low-pressure appliances — chillers using refrigerants such as R-11, R-123 and R-245fa, which sit below 45 psia at 104 °F. The refrigerants themselves are classified by chemistry and by ASHRAE safety group, never as "Type 3."

How do I know if my system is R-410A or R-22?

Read the nameplate on the outdoor unit, which states the factory charge and refrigerant. As a rough cross-check, R-22 systems are generally older and run much lower head pressure than R-410A. Do not guess from pressure alone, and never mix the two — they use different oils and operate at different pressures.

Can you still use R-22 refrigerant?

Yes. HCFC-22 production and import in the US ended on January 1, 2020, but that ended manufacture, not use. Existing R-22 equipment stays legal to operate and to service, using recovered, recycled, reclaimed or stockpiled material. The same logic applies to the R-410A phase-down, which restricts new equipment rather than servicing.

Does an A2L refrigerant need a different certification?

No. EPA has not created an A2L certification, and Section 608 covers A2Ls under the existing Type I, II and III sections. What does change is your equipment — recovery machines, cylinders, hoses and leak detectors must be rated for flammable refrigerants — and the ventilation and ignition-source rules that come from ASHRAE Standard 15 and the equipment listing rather than from Part 82.

Sources

• EPA, Refrigerant Sales Restriction
• EPA, Section 608 Technician Certification Requirements
• EPA, Frequent Questions on the Phasedown of Hydrofluorocarbons
• EPA, Technology Transitions GWP Reference Table
• 40 CFR Part 82, Subpart F