R404A / R507A / R448A / R449A: Composition, GWP and Retrofit Limits

Sun, 20 Sep 2026 · HARMONY TECHNOLOGY (ZHEJIANG) CO., LTD.

These four are not interchangeable. Composition determines glide, and glide determines whether a retrofit is a drop-in or a rebuild.

1. Composition first — everything else follows

Sources — every figure in the table above was checked against the source, not recalled. R448A composition and GWP 1386 (AR4): Arkema Forane® 448A TDS (CAS 75-10-5 / 354-33-6 / 754-12-1 / 811-97-2 / 29118-24-9) and the agas product page. R449A composition 24.3 / 24.7 / 25.7 / 25.3 and GWP 1397 (AR4): Arkema Lower-GWP Guide and public literature (PMC5528183). A GWP figure is only usable together with the assessment report it came from. The same refrigerant carries different values under different reports — R404A is about 3922 under AR4, while literature citing IPCC 2013 gives 3300 — so two correct numbers can still produce a wrong comparison.

Two immediate consequences:

1. R404A and R507A are both ~3900 GWP — swapping one for the other changes nothing about regulatory exposure. They are both high-GWP HFC blends.
2. R448A and R449A are ~1390 GWP and zeotropic — a 60%+ GWP reduction that comes with temperature glide, which is the operating difference that matters.

2. Azeotropic vs zeotropic — the practical difference

⇒ This is why “retrofit” is a system question, not a gas question. A zeotropic blend that leaks and is topped up in vapour phase no longer matches its nameplate composition.

3. What a retrofit actually requires (beyond changing the gas)

⇒ “Drop-in” is a marketing word, not a technical claim. The technical claim is “compatible after the following six checks” — if a supplier cannot name them, the gas is not the question. The mechanism by which an asserted drop-in fails on operating pressure, lubricant miscibility, molecular polarity and flammability class is set out in R22, R32, R410A and R407C: physical properties compared.

4. Regulatory driver (why this matters commercially)

Under the EU F-gas Regulation (EU) 2024/573, GWP thresholds determine which equipment may be placed on the market and which refrigerants may be used for service. A blend with GWP ~3900 and a blend with GWP ~1390 sit on different sides of those thresholds.

⇒ Consequence for procurement: specifying by “the refrigerant that works in our system” is insufficient if the system is placed on an EU market — the GWP of the charge is itself regulated.

5. How to compare offers correctly

Ask for, in writing:

1. Composition (component list with mass %), not just the number.
2. GWP and which assessment report it is quoted against (AR4 vs AR5 vs AR6 give different values for the same refrigerant — a number without the report is not comparable).
3. Glide at the intended evaporating/condensing temperatures.
4. The retrofit checklist for the specific system.
5. CAS numbers of each component, for customs and safety documentation.

⇒ Point 2 is the most common trap: AR4 and AR5 GWP values for these blends differ, and comparing an AR4 figure against an AR5 figure produces a false conclusion.

6. Summary table — what to use where

FAQ

Are R404A and R507A interchangeable? Functionally yes, commercially pointless: R404A is R125/R143a/R134a = 44/52/4 (near-azeotropic, GWP 3922 AR4) and R507A is R125/R143a = 50/50 (azeotropic, GWP 3985 AR4) — swapping one for the other leaves your regulatory exposure unchanged.

Which GWP figure should I quote for R404A? Always quote the number together with its assessment report. R404A is about 3922 on AR4, while sources citing the IPCC 2013 basis give about 3300 — two correct numbers that produce a wrong conclusion when compared without their basis.

What has to change when retrofitting an R404A system to R448A or R449A? Both are zeotropic blends (GWP 1386 and 1397 AR4), so the retrofit needs full-recharge discipline — charge as liquid and verify composition and glide — rather than a top-up.

Why is the blend choice a commercial question in the EU? Under Regulation (EU) 2024/573 the GWP of the charge determines whether equipment may be placed on the market and which refrigerants may be used for service; a ~3900 blend and a ~1390 blend sit on different sides of those thresholds.

Related reading

• How the blend is entered, and why the line item follows the composition — HS codes 2026 — classification of mixtures
• Charge limits when the replacement is A2L — where the flammable-refrigerant limit binds and why it is expressed per m³: A2L charge amount calculation
• Comparing two offers on the same basis — the batch certificate is where a claim becomes a number: Reading a COA

What we can provide

For any of these blends we can supply the component list with mass percentages, CAS numbers for each component, the GWP with its assessment-report basis, and relevant safety classification — so your engineering team can evaluate a retrofit against its own system rather than against a marketing claim.

Contact us with: the existing refrigerant, the system type, and the destination market.

Prepared by Harmony Technology (Zhejiang) Co., Ltd. — a trading company. Technical data above is referenced to public standards; system-specific retrofit decisions remain the responsibility of the qualifying engineer.