R-408A PT Chart and Refrigerant Profile

Where you will find R-408A

R-408A is an HCFC service blend for R-502 equipment, sold by Arkema as Forane FX10 and Forane 408A. It combines R-22 with the HFCs R-143a and R-125. A-Gas lists it for retrofitting R-502 systems in medium- and low-temperature refrigeration, and Copeland approves it for low- and medium-temperature compressors “for service applications only”.

EPA’s SNAP program listed it on Aug 26 1994 as acceptable for retrofit in commercial ice machines, cold storage, industrial process refrigeration, remote condensing units, supermarket and stand-alone equipment, food processing and dispensing equipment, and refrigerated transport.

Look for a retrofit tag reading R-408A or FX10 on a system whose nameplate says R-502. The legacy cylinder color assigned in AHRI Guideline N-2017 was medium purple, close to R-502’s lavender; containers made since 2020 are light green-gray, so read the label.

Charging R-408A

R-408A has a small glide: 0.6°F at 40°F evaporating on this site’s table. It is still a three-part blend. Arkema’s retrofit guide says to charge it in the liquid phase only. Meter the liquid in slowly so it flashes before the compressor.

For an R-502 conversion, Arkema’s starting point is 85-90% of the original R-502 charge by weight, then adjust to the system. Arkema also says not to mix R-408A with R-502 or top off an R-502 system with it.

Arkema expects these differences against R-502:

• Suction pressure 1-3 psi lower.
• Discharge pressure 0-5 psi higher.
• Discharge temperature 10-35°F higher.

This site’s tables agree on the pressures: R-408A reads 77.9 psig at a 40°F dew point against 77.5 psig for R-502, and 217.3 psig at a 100°F bubble point against 211.8 psig for R-502. Check discharge temperature against the compressor maker’s limit after a conversion.

For superheat, read suction pressure against the dew column with the superheat calculator. On TXV systems, charge by subcooling to the manufacturer’s target with the subcooling calculator, using the bubble column. With under 1°F of glide the two columns are close, but use the right one.

Oil and compatibility

R-408A can run on the oils already in an R-502 system. Arkema says no oil change is required when converting from R-502. Linde and A-Gas list mineral oil, alkylbenzene and POE.

Compressor makers are more specific:

• Copeland prefers AB mixed with mineral oil, at least 50% AB, for retrofits. Alternates are POE-32 mixed with mineral oil (at least 50% POE) or straight POE-32.
• BITZER lists AB, with POE “with limitations”.

Follow the compressor maker. The refrigerant oil types guide explains the oil families.

Safety, handling and recovery

R-408A is ASHRAE class A1: lower toxicity, no flame propagation. It is an ozone-depleting refrigerant, ODP 0.026 from its HCFC-22 share (40 CFR 82 Appendix B). Knowingly venting it is prohibited, recovery is required, and sales are restricted to certified technicians.

It is a high-pressure refrigerant under 40 CFR 82.152: this site’s table gives 230.1 psig (244.8 psia) at a 104°F bubble point, inside the 170-355 psia band, as for R-502 itself. Type II or Universal certification covers it.

Appliances with 50 lb or more fall under the ODS leak-repair rules in 40 CFR 82.157. Recovered R-408A cannot be sold to a new owner unless an EPA-certified reclaimer has reclaimed it.

Status and replacements

Since Jan 1 2010, HCFC-22 may be used as a refrigerant only in equipment made before that date, and US production and import of HCFC-22 ended Jan 1 2020 (40 CFR 82.15). R-408A is therefore a service-only refrigerant on recovered, reclaimed or remaining stock. It also contains HFC-125 and HFC-143a, and the AIM Act Technology Transitions rule names it among restricted refrigerants in several new-equipment sectors, though HCFC rules already bar it from new equipment.

No source found confirms that Arkema still makes FX10; its product page no longer loads and the 2025 Technical Digest has no R-408A entry. That digest lists Forane 404A as a replacement or retrofit for R-408A.

The main paths off R-408A or R-502 are R-404A and R-507A, both on POE. The R-502 replacement comparison lines up R-408A with the HFC options, and the R-404A replacement guide covers the next step down in GWP.

Common questions

R-408A vs R-404A?

R-408A is an R-22-based service blend that can stay on the R-502 system’s oil. R-404A is an all-HFC replacement that needs POE. Arkema now lists R-404A as a retrofit for R-408A systems.