R-455A PT Chart and Refrigerant Profile

Where you will find R-455A

R-455A is Solstice L40X, an A2L blend of R-1234yf and R-32 with 3% CO2 (R-744). Solstice lists it for new low-, medium- and high-temperature commercial refrigeration: plug-in cases, condensing units, food service equipment and water-loop systems (Solstice L40X). It is a new-equipment replacement for R-404A, R-507A and R-448A, not a retrofit gas.

Identify it from the nameplate and cylinder label. It is easy to confuse with R-454C, which has the same 21.5% R-32 and the same AR4 GWP but no CO2. The two have different PT charts: at 40°F the computed bubble pressure is 101.9 psig for R-455A and 81.4 psig for R-454C.

Charging R-455A

R-455A has more glide than any other blend in this site’s commercial refrigeration group: about 23.0°F at 40°F evaporating and 19.0°F at 100°F condensing in the computed data. The 3% CO2, which boils far lower than the other two components, is what takes it well past the glide of R-454C. Charge it as liquid only; vapor drawn from the cylinder would be rich in the more volatile components and shift the blend.

At 40°F the computed bubble pressure is 101.9 psig and the dew pressure 64.7 psig, about 37 psi apart. Reading the right column is essential: dew with suction pressure for superheat, bubble with liquid-line pressure for subcooling. The glide calculator gives the spread at your actual pressure, and the PT chart guide explains why the columns differ.

The computed chart has a known offset. The bubble side agrees with Honeywell’s R-455A data within 0.25 psi, but the dew line reads 1 to 5 psi (2.3–3%) low, from the R-32/R-1234yf and CO2 interaction parameters in the CoolProp model. The validation section below lists the points. For close superheat readings, cross-check suction saturation against the Solstice L40X PT chart.

Charge new equipment to the manufacturer’s instructions. On TXV and EEV systems, check the subcooling target with the subcooling calculator; self-contained plug-in units are charged by weight to the nameplate. The target superheat calculator applies to fixed-metering comfort air conditioners only.

Oil and compatibility

Solstice lists POE oil for R-455A. Use the grade on the compressor label.

Because R-455A is A2L and listed for new equipment, converting an existing A1 system is not a simple oil decision; the equipment needs a flammable-refrigerant listing and has to meet EPA’s SNAP use conditions. See the oil types guide.

Safety, handling and recovery

R-455A is class A2L: lower toxicity and mildly flammable, with a burning velocity of 10 cm/s or less (flammability classes). EPA lists it as acceptable subject to use conditions in commercial and industrial refrigeration, including cold storage (89 FR 50410, June 13, 2024); the use conditions include red (PMS #185) flammable-refrigerant markings. It is not exempt from the venting prohibition, CO2 content notwithstanding.

Under Section 608 it is a high-pressure appliance refrigerant (40 CFR 82.152), so Type II or Universal certification is required. Recover to 0 in Hg on systems under 200 lb and 10 in Hg on 200 lb or more (40 CFR 82.156). Use a recovery machine certified under Appendix B4 of 40 CFR 82.158, which adds UL 1963 Supplement SB for flammable refrigerants; see recovery machine compatibility. Equipment makers require A2L-rated service equipment on A2L systems, so check the manual for gauges, vacuum pumps and leak detectors. The A2L refrigerants guide covers the field changes.

The 40 CFR 84.106 leak repair rules apply from January 1, 2026 to appliances with 15 lb or more of a substitute with GWP above 53, which includes R-455A.

The legacy label color for R-455A is sea-foam green. New containers since January 1, 2020 are light green-gray (RAL 7044) under AHRI Guideline N-2017, with a red band on the shoulder or top for flammable refrigerants. Many A2L cylinders use left-hand thread valves as an industry practice, so check the valve before connecting an adapter. See cylinder colors.

Status and replacements

R-455A’s GWP is 148 on the AR4 basis and 145.9 in EPA’s 40 CFR 84.64 calculation. That is below the interim limits set by the May 2026 final rule (91 FR 31284), 1,400 for new remote condensing units from July 27, 2026 and supermarket systems from January 1, 2027 and 700 for new cold storage from July 27, 2026, and below the lower limits that apply from January 1, 2032 under 40 CFR 84.54: 300 for systems under 200 lb and cascade high sides, 150 for systems of 200 lb or more.

Only the R-32 in R-455A is an HFC under the AIM Act allowance phasedown; R-1234yf is an HFO and CO2 is not a regulated substance under Part 84. From January 1, 2029, servicing supermarket systems, refrigerated transport and automatic commercial ice makers must use reclaimed refrigerant (40 CFR 84.112(e)).

There is no listed successor. The closest alternatives for new equipment are R-454C and CO2 (R-744) systems; for large systems over 200 lb, R-455A and R-454C both sit under the 150 limit, while R-454A does not. See the R-404A replacement comparison.

Common questions

What is the difference between R-455A and R-454C?

Both are A2L blends with 21.5% R-32 and an AR4 GWP of 148. R-455A swaps 3% of the R-1234yf for CO2, which adds about 8°F of glide (about 23.0°F against 14.9°F at 40°F evaporating, computed) and raises the bubble pressure. They are not interchangeable.

Can R-455A be used to retrofit an R-404A system?

Solstice lists R-455A for new equipment. As an A2L it needs equipment listed for a flammable refrigerant and the SNAP use conditions, so it is not a field retrofit for an A1 system.