R-455A
Zeotropic ternary blend with CO₂ component (3% R-744 / 21.5% R-32 / 75.5% R-1234yf mass) — A2L, GWP 148, ~22°F temperature glide. Honeywell Solstice L40X / N40 family. Low-GWP commercial refrigeration alternative to R-454C.
Lower toxicity. Flame propagates in air at 60°C, but with a low burning velocity (≤ 10 cm/s) and a heat of combustion < 19,000 kJ/kg. Requires A2L-rated equipment, leak detection, and charge limits per UL 60335-2-40 and ASHRAE 15. R-32, R-454B, R-1234yf, R-1234ze(E), R-452B, R-454C, R-455A, R-516A are A2L.
- Flammability
- Low (burning velocity ≤ 10 cm/s)
- Toxicity
- Lower (OEL ≥ 400 ppm)
Classification per ANSI/ASHRAE Standard 34-2022. See full reference.
Saturation pressure-temperature curve
Saturation values from CoolProp 7.2.0 HEOS::CarbonDioxide[0.05962]&R32[0.36141]&R1234yf[0.57897]. Operating pressure on a running system differs — see the operating-pressure references for in-use values.
R-455A PT chart PDF — printable saturation table
Looking for the R-455A PT chart PDF for shop reference? The complete pressure-temperature saturation table is below — every 1° increment from −40°F to 150°F (or to the refrigerant's critical temperature). Use the Print / Save as PDF button in the table header to download a clean, table-only PDF (the rest of the page is hidden from the print output). Important service temperatures (normal boiling point, freezing point of water, residential AC evap and condenser targets) are tinted and tagged in the table for at-a-glance shop reference.
R-455A PT Chart — Pressure-Temperature Saturation Table
1° increments · Source: CoolProp 7.2.0 / manufacturer datasheet · hvacptcharts.com
| Temp (°F) | Bubble (PSIG) | Dew (PSIG) | Glide (PSI) |
|---|---|---|---|
| -40°F | 10.7 | -0.6 | 11.2 |
| -39°F | 11.3 | -0.2 | 11.4 |
| -38°F | 11.9 | 0.2 | 11.6 |
| -37°F | 12.5 | 0.6 | 11.9 |
| -36°F | 13.1 | 1.0 | 12.1 |
| -35°F | 13.8 | 1.4 | 12.3 |
| -34°F | 14.4 | 1.9 | 12.5 |
| -33°F | 15.1 | 2.3 | 12.8 |
| -32°F | 15.7 | 2.7 | 13.0 |
| -31°F | 16.4 | 3.2 | 13.2 |
| -30°F | 17.1 | 3.6 | 13.5 |
| -29°F | 17.8 | 4.1 | 13.7 |
| -28°F | 18.5 | 4.6 | 14.0 |
| -27°F | 19.3 | 5.1 | 14.2 |
| -26°F | 20.0 | 5.6 | 14.5 |
| -25°F | 20.8 | 6.1 | 14.7 |
| -24°F | 21.5 | 6.6 | 15.0 |
| -23°F | 22.3 | 7.1 | 15.2 |
| -22°F | 23.1 | 7.6 | 15.5 |
| -21°F | 23.9 | 8.2 | 15.7 |
| -20°F | 24.8 | 8.8 | 16.0 |
| -19°F | 25.6 | 9.3 | 16.3 |
| -18°F | 26.4 | 9.9 | 16.5 |
| -17°F | 27.3 | 10.5 | 16.8 |
| -16°F | 28.2 | 11.1 | 17.1 |
| -15°F | 29.1 | 11.7 | 17.4 |
| -14°F | 30.0 | 12.3 | 17.6 |
| -13°F | 30.9 | 12.9 | 17.9 |
| -12°F | 31.8 | 13.6 | 18.2 |
| -11°F | 32.8 | 14.3 | 18.5 |
| -10°F | 33.7 | 14.9 | 18.8 |
| -9°F | 34.7 | 15.6 | 19.1 |
| -8°F | 35.7 | 16.3 | 19.4 |
| -7°F | 36.7 | 17.0 | 19.7 |
| -6°F | 37.7 | 17.7 | 20.0 |
| -5°F | 38.7 | 18.4 | 20.3 |
| -4°F | 39.8 | 19.2 | 20.6 |
| -3°F | 40.9 | 19.9 | 20.9 |
| -2°F | 41.9 | 20.7 | 21.2 |
| -1°F | 43.0 | 21.5 | 21.5 |
| 0°F | 44.1 | 22.3 | 21.9 |
| 1°F | 45.3 | 23.1 | 22.2 |
| 2°F | 46.4 | 23.9 | 22.5 |
| 3°F | 47.6 | 24.7 | 22.8 |
| 4°F | 48.7 | 25.6 | 23.2 |
| 5°F | 49.9 | 26.5 | 23.5 |
| 6°F | 51.1 | 27.3 | 23.8 |
| 7°F | 52.4 | 28.2 | 24.1 |
| 8°F | 53.6 | 29.1 | 24.5 |
| 9°F | 54.9 | 30.1 | 24.8 |
| 10°F | 56.1 | 31.0 | 25.2 |
| 11°F | 57.5 | 31.9 | 25.5 |
| 12°F | 58.8 | 32.9 | 25.9 |
| 13°F | 60.1 | 33.9 | 26.2 |
| 14°F | 61.4 | 34.9 | 26.5 |
| 15°F | 62.8 | 35.9 | 26.9 |
| 16°F | 64.2 | 36.9 | 27.3 |
| 17°F | 65.6 | 38.0 | 27.6 |
| 18°F | 67.0 | 39.0 | 28.0 |
| 19°F | 68.5 | 40.1 | 28.3 |
| 20°FMT evap target | 69.9 | 41.2 | 28.7 |
| 21°F | 71.4 | 42.3 | 29.1 |
| 22°F | 72.9 | 43.5 | 29.5 |
| 23°F | 74.4 | 44.6 | 29.8 |
| 24°F | 76.0 | 45.8 | 30.2 |
| 25°F | 77.5 | 46.9 | 30.6 |
| 26°F | 79.1 | 48.1 | 30.9 |
| 27°F | 80.7 | 49.4 | 31.3 |
| 28°F | 82.3 | 50.6 | 31.7 |
| 29°F | 83.9 | 51.8 | 32.1 |
| 30°F | 85.6 | 53.1 | 32.5 |
| 31°F | 87.3 | 54.4 | 32.9 |
| 32°FH₂O freeze | 89.0 | 55.7 | 33.3 |
| 33°F | 90.7 | 57.0 | 33.6 |
| 34°F | 92.4 | 58.4 | 34.0 |
| 35°FMT box temp | 94.2 | 59.7 | 34.4 |
| 36°F | 95.9 | 61.1 | 34.8 |
| 37°F | 97.7 | 62.5 | 35.2 |
| 38°F | 99.6 | 64.0 | 35.6 |
| 39°F | 101.4 | 65.4 | 36.0 |
| 40°F | 103.3 | 66.9 | 36.4 |
| 41°F | 105.2 | 68.3 | 36.8 |
| 42°F | 107.1 | 69.8 | 37.2 |
| 43°F | 109.0 | 71.4 | 37.6 |
| 44°F | 111.0 | 72.9 | 38.0 |
| 45°F | 112.9 | 74.5 | 38.5 |
| 46°F | 114.9 | 76.1 | 38.9 |
| 47°F | 117.0 | 77.7 | 39.3 |
| 48°F | 119.0 | 79.3 | 39.7 |
| 49°F | 121.1 | 81.0 | 40.1 |
| 50°F | 123.2 | 82.6 | 40.5 |
| 51°F | 125.3 | 84.3 | 40.9 |
| 52°F | 127.4 | 86.1 | 41.3 |
| 53°F | 129.6 | 87.8 | 41.8 |
| 54°F | 131.8 | 89.6 | 42.2 |
| 55°F | 134.0 | 91.4 | 42.6 |
| 56°F | 136.2 | 93.2 | 43.0 |
| 57°F | 138.4 | 95.0 | 43.4 |
| 58°F | 140.7 | 96.9 | 43.9 |
| 59°F | 143.0 | 98.8 | 44.3 |
| 60°F | 145.4 | 100.7 | 44.7 |
| 61°F | 147.7 | 102.6 | 45.1 |
| 62°F | 150.1 | 104.6 | 45.6 |
| 63°F | 152.5 | 106.5 | 46.0 |
| 64°F | 154.9 | 108.5 | 46.4 |
| 65°F | 157.4 | 110.6 | 46.8 |
| 66°F | 159.9 | 112.6 | 47.2 |
| 67°F | 162.4 | 114.7 | 47.7 |
| 68°F | 164.9 | 116.8 | 48.1 |
| 69°F | 167.5 | 119.0 | 48.5 |
| 70°F | 170.1 | 121.1 | 49.0 |
| 71°F | 172.7 | 123.3 | 49.4 |
| 72°F | 175.3 | 125.5 | 49.8 |
| 73°F | 178.0 | 127.8 | 50.2 |
| 74°F | 180.7 | 130.1 | 50.6 |
| 75°F | 183.4 | 132.4 | 51.1 |
| 76°F | 186.2 | 134.7 | 51.5 |
| 77°F | 188.9 | 137.0 | 51.9 |
| 78°F | 191.8 | 139.4 | 52.3 |
| 79°F | 194.6 | 141.8 | 52.7 |
| 80°F | 197.4 | 144.3 | 53.2 |
| 81°F | 200.3 | 146.8 | 53.6 |
| 82°F | 203.2 | 149.3 | 54.0 |
| 83°F | 206.2 | 151.8 | 54.4 |
| 84°F | 209.2 | 154.3 | 54.8 |
| 85°F | 212.2 | 156.9 | 55.2 |
| 86°F | 215.2 | 159.6 | 55.6 |
| 87°F | 218.2 | 162.2 | 56.0 |
| 88°F | 221.3 | 164.9 | 56.5 |
| 89°F | 224.4 | 167.6 | 56.8 |
| 90°F | 227.6 | 170.3 | 57.3 |
| 91°F | 230.8 | 173.1 | 57.6 |
| 92°F | 234.0 | 175.9 | 58.0 |
| 93°F | 237.2 | 178.8 | 58.4 |
| 94°F | 240.5 | 181.6 | 58.8 |
| 95°FAHRI design ambient | 243.8 | 184.6 | 59.2 |
| 96°F | 247.1 | 187.5 | 59.6 |
| 97°F | 250.4 | 190.5 | 60.0 |
| 98°F | 253.8 | 193.5 | 60.4 |
| 99°F | 257.2 | 196.5 | 60.7 |
| 100°F | 260.7 | 199.6 | 61.1 |
| 101°F | 264.2 | 202.7 | 61.5 |
| 102°F | 267.7 | 205.8 | 61.8 |
| 103°F | 271.2 | 209.0 | 62.2 |
| 104°F | 274.8 | 212.3 | 62.5 |
| 105°F | 278.4 | 215.5 | 62.9 |
| 106°F | 282.0 | 218.8 | 63.2 |
| 107°F | 285.7 | 222.1 | 63.6 |
| 108°F | 289.4 | 225.5 | 63.9 |
| 109°F | 293.1 | 228.9 | 64.2 |
| 110°FCond saturation | 296.9 | 232.3 | 64.6 |
| 111°F | 300.7 | 235.8 | 64.9 |
| 112°F | 304.5 | 239.3 | 65.2 |
| 113°F | 308.4 | 242.9 | 65.5 |
| 114°F | 312.3 | 246.5 | 65.8 |
| 115°F | 316.2 | 250.1 | 66.1 |
| 116°F | 320.1 | 253.8 | 66.4 |
| 117°F | 324.1 | 257.5 | 66.6 |
| 118°F | 328.2 | 261.3 | 66.9 |
| 119°F | 332.2 | 265.1 | 67.2 |
| 120°F | 336.3 | 268.9 | 67.4 |
| 121°F | 340.4 | 272.8 | 67.7 |
| 122°F | 344.6 | 276.7 | 67.9 |
| 123°F | 348.8 | 280.7 | 68.1 |
| 124°F | 353.0 | 284.7 | 68.4 |
| 125°F | 357.3 | 288.7 | 68.6 |
| 126°F | 361.6 | 292.8 | 68.8 |
| 127°F | 365.9 | 297.0 | 69.0 |
| 128°F | 370.3 | 301.2 | 69.1 |
| 129°F | 374.7 | 305.4 | 69.3 |
| 130°F | 379.1 | 309.7 | 69.5 |
| 131°F | 383.6 | 314.0 | 69.6 |
| 132°F | 388.1 | 318.4 | 69.7 |
| 133°F | 392.6 | 322.8 | 69.8 |
| 134°F | 397.2 | 327.3 | 70.0 |
| 135°F | 401.8 | 331.8 | 70.0 |
| 136°F | 406.5 | 336.4 | 70.1 |
| 137°F | 411.2 | 341.0 | 70.2 |
| 138°F | 415.9 | 345.7 | 70.2 |
| 139°F | 420.6 | 350.4 | 70.3 |
| 140°F | 425.4 | 355.2 | 70.3 |
| 141°F | 430.3 | 360.0 | 70.3 |
| 142°F | 435.1 | 364.9 | 70.2 |
| 143°F | 440.0 | 369.8 | 70.2 |
| 144°F | 444.9 | 374.8 | 70.1 |
| 145°F | 449.9 | 379.9 | 70.0 |
| 146°F | 454.9 | 385.0 | 69.9 |
| 147°F | 459.9 | 390.2 | 69.8 |
| 148°F | 465.0 | 395.4 | 69.6 |
| 149°F | 470.1 | 400.7 | 69.4 |
| 150°F | 475.3 | 406.0 | 69.2 |
| Temp (°C) | Bubble (kPa) | Dew (kPa) | Glide (kPa) |
|---|---|---|---|
| -40°C | 74 | -4 | 77 |
| -39°C | 81 | 1 | 80 |
| -38°C | 89 | 6 | 83 |
| -37°C | 97 | 11 | 86 |
| -36°C | 105 | 16 | 88 |
| -35°C | 113 | 22 | 91 |
| -34°C | 122 | 28 | 94 |
| -33°C | 131 | 34 | 97 |
| -32°C | 140 | 40 | 100 |
| -31°C | 150 | 46 | 103 |
| -30°C | 159 | 53 | 107 |
| -29°C | 170 | 60 | 110 |
| -28°C | 180 | 67 | 113 |
| -27°C | 191 | 74 | 117 |
| -26°C | 202 | 81 | 120 |
| -25°C | 213 | 89 | 124 |
| -24°C | 225 | 97 | 127 |
| -23°C | 236 | 106 | 131 |
| -22°C | 249 | 114 | 135 |
| -21°C | 261 | 123 | 138 |
| -20°C | 274 | 132 | 142 |
| -19°C | 288 | 142 | 146 |
| -18°C | 301 | 151 | 150 |
| -17°C | 315 | 161 | 154 |
| -16°C | 330 | 172 | 158 |
| -15°C | 344 | 182 | 162 |
| -14°C | 359 | 193 | 166 |
| -13°C | 375 | 205 | 170 |
| -12°C | 391 | 216 | 174 |
| -11°C | 407 | 228 | 179 |
| -10°C | 424 | 241 | 183 |
| -9°C | 441 | 253 | 188 |
| -8°C | 458 | 266 | 192 |
| -7°CMT evap target | 476 | 280 | 196 |
| -6°C | 494 | 293 | 201 |
| -5°C | 513 | 308 | 206 |
| -4°C | 532 | 322 | 210 |
| -3°C | 552 | 337 | 215 |
| -2°C | 572 | 352 | 220 |
| -1°C | 592 | 368 | 224 |
| 0°CH₂O freeze | 613 | 384 | 229 |
| 1°C | 635 | 401 | 234 |
| 2°CMT box temp | 657 | 418 | 239 |
| 3°C | 679 | 435 | 244 |
| 4°C | 702 | 453 | 249 |
| 5°C | 725 | 471 | 254 |
| 6°C | 749 | 490 | 259 |
| 7°C | 773 | 509 | 264 |
| 8°C | 798 | 529 | 269 |
| 9°C | 823 | 549 | 274 |
| 10°C | 849 | 570 | 279 |
| 11°C | 875 | 591 | 284 |
| 12°C | 902 | 613 | 290 |
| 13°C | 930 | 635 | 295 |
| 14°C | 958 | 658 | 300 |
| 15°C | 986 | 681 | 305 |
| 16°C | 1,015 | 705 | 311 |
| 17°C | 1,045 | 729 | 316 |
| 18°C | 1,075 | 754 | 321 |
| 19°C | 1,106 | 779 | 326 |
| 20°C | 1,137 | 806 | 332 |
| 21°C | 1,169 | 832 | 337 |
| 22°C | 1,202 | 859 | 342 |
| 23°C | 1,235 | 887 | 347 |
| 24°C | 1,268 | 916 | 353 |
| 25°C | 1,303 | 945 | 358 |
| 26°C | 1,338 | 975 | 363 |
| 27°C | 1,373 | 1,005 | 368 |
| 28°C | 1,409 | 1,036 | 373 |
| 29°C | 1,446 | 1,068 | 379 |
| 30°C | 1,484 | 1,100 | 384 |
| 31°C | 1,522 | 1,133 | 389 |
| 32°C | 1,561 | 1,167 | 394 |
| 33°C | 1,600 | 1,201 | 399 |
| 34°C | 1,640 | 1,237 | 403 |
| 35°CAHRI design ambient | 1,681 | 1,272 | 408 |
| 36°C | 1,722 | 1,309 | 413 |
| 37°C | 1,764 | 1,347 | 418 |
| 38°C | 1,807 | 1,385 | 422 |
| 39°C | 1,850 | 1,424 | 427 |
| 40°C | 1,895 | 1,463 | 431 |
| 41°C | 1,939 | 1,504 | 436 |
| 42°C | 1,985 | 1,545 | 440 |
| 43°CCond saturation | 2,031 | 1,588 | 444 |
| 44°C | 2,078 | 1,631 | 448 |
| 45°C | 2,126 | 1,675 | 452 |
| 46°C | 2,175 | 1,719 | 455 |
| 47°C | 2,224 | 1,765 | 459 |
| 48°C | 2,274 | 1,812 | 462 |
| 49°C | 2,325 | 1,859 | 465 |
| 50°C | 2,376 | 1,908 | 468 |
| 51°C | 2,428 | 1,957 | 471 |
| 52°C | 2,481 | 2,008 | 474 |
| 53°C | 2,535 | 2,059 | 476 |
| 54°C | 2,590 | 2,111 | 478 |
| 55°C | 2,645 | 2,165 | 480 |
| 56°C | 2,701 | 2,220 | 481 |
| 57°C | 2,758 | 2,275 | 483 |
| 58°C | 2,816 | 2,332 | 484 |
| 59°C | 2,874 | 2,390 | 484 |
| 60°C | 2,933 | 2,449 | 484 |
| 61°C | 2,993 | 2,509 | 484 |
| 62°C | 3,054 | 2,571 | 484 |
| 63°C | 3,116 | 2,633 | 482 |
| 64°C | 3,178 | 2,697 | 481 |
| 65°C | 3,241 | 2,763 | 479 |
Full saturation values at 1° increments — toggle between °F / PSIG and °C / kPa. Use Print / Save as PDF for laminated shop reference, or download the CSV / JSON below for use in other tools. R-455A PT chart data: CoolProp 7.2.0 (REFPROP-compatible Helmholtz EOS) or manufacturer datasheet, validated against AHRI Standard 700-2019.
At a glance
Chemistry
Lubricant compatibility
POE required. A2L. Very low GWP — meets EU F-Gas <150 threshold. CO2 component contributes a significant temperature glide (~7-9 K).
Blend composition
- CO23.0%
- R-3221.5%
- R-1234yf75.5%
Trade names
- Solstice L40XHoneywell
Common applications
- Commercial refrigeration (low and medium temp)
- Supermarket cases
- R-404A retrofit (Honeywell L40X product line)
Properties
- Boiling point (1 atm)-52.3°C / -62.1°F
- Critical pointNo single point — blend critical locus
- Molar mass87.45 g/mol
- Temperature glide21.6°F
- ODP0
- GWP (AR5, 100-yr)148
- GWP (AR6, 100-yr)167
What is R-455A?
R-455A is a ternary zeotropic blend combining R-744 (CO₂), R-32, and R-1234yf in 3/21.5/75.5 mass proportions [ashrae34]. The R-744 component is unusual — only 3% by mass — but contributes significant volumetric capacity and slightly raises the operating pressure envelope. The R-1234yf component (75.5%, GWP 4) is the GWP-diluting majority component; the R-32 component (21.5%, GWP 675) provides primary capacity.
The defining trade-off is a very large temperature glide of approximately 22°F — among the largest of any commercial refrigerant. The glide is the price of the very-low GWP (148, identical to R-454C) and the wide range of pure-component boiling points (R-744 at −109°F, R-32 at −61°F, R-1234yf at −21°F).
Where R-455A is used
- Low-temperature commercial refrigeration — walk-in freezers, frozen food cases (new equipment)
- Medium-temperature commercial refrigeration — refrigerated cases (new equipment)
- Self-contained commercial refrigeration equipment
- Honeywell Solstice L40X / N40 trade names — major OEM adoption in EU
Regulatory & phase-down status
R-455A is one of the dominant low-GWP A2L blends for new commercial refrigeration equipment under EPA AIM Act and EU F-Gas Regulation [aimact][eufgas]. GWP 148 sits below the EU F-Gas 150-GWP threshold and provides comfortable headroom under EPA AIM Act commercial refrigeration thresholds.
R-454C and R-455A serve as competing low-GWP A2L choices with identical GWP. The differences are composition-specific: R-455A includes the 3% R-744 component for capacity and slightly different pressure characteristics; R-454C is a binary R-32/R-1234yf blend with simpler chemistry. OEM preference and equipment optimization typically drive the choice between them.
Service notes
POE oil required — same lubricant family as R-410A and R-32 [ahri700]. A2L safety class requires sealed motors, charge limits per UL 60335-2-89 and ASHRAE 15, A2L-rated leak detection in some installations, and nitrogen-purged brazing [ul60335][ashrae15].
The 22°F temperature glide is the largest among mainstream commercial refrigerants and significantly affects service measurement. Use dew temperature for superheat math (suction line) and bubble temperature for subcooling (liquid line). The R-744 component requires attention to fractionation behavior during partial charging — full recovery and recharge is the correct service approach.
Temperature glide
R-455A is a zeotropic blend: at constant pressure it boils across a temperature range rather than at a single point. This affects EXV sizing, charge measurement, and superheat measurement. Use the dew curve for superheat, bubble curve for subcooling.
Operating cycle
Phase-down timeline
R-455A is not currently regulated by AIM Act or EU F-Gas phase-down. Its very low GWP (148) places it below regulatory thresholds. No published phase-down milestones exist for this refrigerant — it is a forward-compatible option for the current low-GWP transition rather than a refrigerant being phased out.
Global warming potential, in context
Commercial refrigeration — medium temperature
Retrofit and replacement paths
R-455A replaces
Reading the R-455A PT chart — very large glide demands careful curve selection
R-455A is a ternary zeotropic blend with approximately 22°F glide — among the largest of any commercial refrigerant. The PT chart shows two distinct curves (bubble and dew) with substantial vertical separation. Reading the chart requires deliberate attention to which curve applies for each measurement.
For suction-line superheat measurement, use the dew curve. The dew temperature at the measured suction pressure is the saturation reference. For liquid-line subcooling measurement, use the bubble curve. Using the wrong curve introduces measurement error equal to the glide — for R-455A this is up to 22°F, large enough to make charging decisions catastrophically wrong.
R-455A's glide is unusually large because of the three-component composition with widely-different pure-component boiling points. Even compared to other zeotropic blends (R-454C at 14°F, R-407C at 11°F, R-448A at 10°F), R-455A's glide is substantially larger. Service measurement on R-455A demands the most careful curve selection of any common commercial refrigerant.
The 3/21.5/75.5 R-744/R-32/R-1234yf ternary composition is unique
R-455A is one of very few mainstream refrigerants that combines a fluorocarbon HFC/HFO portion with a natural-refrigerant component (R-744 CO₂). The 3% R-744 fraction is small in mass but disproportionate in effect — CO₂'s very high vapor pressure raises the blend's overall operating pressure envelope and improves volumetric refrigerating capacity compared to a binary R-32/R-1234yf blend at the same GWP.
The mass-weighted GWP arithmetic: 0.03 × 1 + 0.215 × 675 + 0.755 × 4 = 0.03 + 145 + 3 = 148 [ipccar5]. The R-744 component contributes negligibly to GWP (CO₂ is the GWP=1 reference) and slightly raises the blend's pressure envelope. The R-32 and R-1234yf components dominate the GWP arithmetic and the thermodynamic behavior.
R-455A illustrates an interesting refrigerant chemistry direction — blending natural refrigerant components (R-744) with synthetic HFC/HFO components to optimize the trade-off between GWP, flammability, capacity, and operating pressure. Other examples include R-466A (R-32/R-125/R-13I1 with iodotrifluoromethane). These hybrid approaches let designers tune specific properties beyond what pure HFC blends can achieve.
Pressure envelope raised by R-744 component
R-455A's saturation pressures run approximately 20% higher than R-454C across the operating range, with the difference driven by the R-744 component. At 70°F R-455A bubble is 170 PSIG vs R-454C's 141 PSIG (CoolProp 7.2.0). At 95°F, R-455A bubble is approximately 260 PSIG vs R-454C's 220 PSIG.
The dew pressure delta is smaller — at 70°F R-455A dew is 121 PSIG vs R-454C's 112 PSIG. The wider bubble/dew spread on R-455A (49 PSI at 70°F) compared to R-454C (29 PSI at 70°F) reflects the larger glide.
Standard 500-800 PSI manifold gauges handle the R-455A envelope. Equipment design for R-455A may use slightly more robust pressure-rating components than R-454C equipment but the difference is typically within OEM standard inventory. The pressure delta is small enough that R-454C-rated service equipment generally handles R-455A.
GWP 148 — same regulatory positioning as R-454C
R-455A's GWP 148 matches R-454C's exactly — both blends are engineered to the same EU F-Gas 150-GWP threshold for several commercial refrigeration categories [eufgas]. The regulatory advantage is identical between the two blends.
The composition strategies differ: R-454C uses high R-1234yf content (78.5%) with R-32 (21.5%) only. R-455A uses similar R-32 content (21.5%) with high R-1234yf (75.5%) and the small R-744 addition (3%). Both arrive at GWP 148 through different mass-weighted arithmetic paths.
For practical regulatory compliance, R-454C and R-455A are interchangeable — both clear EU F-Gas thresholds and EPA AIM Act provisions for new commercial refrigeration equipment. The differentiation between them is operational (binary simplicity vs ternary capacity boost; 14°F vs 22°F glide; OEM patent and supply preferences) rather than regulatory.
Reading R-455A at commercial refrigeration service temperatures
R-455A is used in commercial refrigeration at sub-freezing evaporator temperatures. Saturation values (bubble / dew showing the 22°F glide):
- −40°F (deep freezer) — bubble approximately 11 PSIG / dew approximately 1 inHg vac.
- −20°F (frozen food) — bubble approximately 27 PSIG / dew approximately 11 PSIG.
- 0°F (freezer) — bubble approximately 53 PSIG / dew approximately 34 PSIG.
- 30°F (refrigerated case) — bubble approximately 95 PSIG / dew approximately 70 PSIG.
- 70°F (bench reference) — bubble 170 PSIG / dew 121 PSIG.
- 95°F (summer condensing) — bubble approximately 260 PSIG / dew approximately 200 PSIG.
The 49 PSI bubble/dew spread at 70°F is the largest among common refrigerants. For service measurement: use dew for superheat (suction line) and bubble for subcooling (liquid line). The site's calculators handle the curve selection automatically when R-455A is selected.
Service procedures — A2L with very-large glide considerations
R-455A service uses standard A2L procedures with additional attention to the very-large glide and the fractionation behavior of the three-component blend during partial charging.
| Equipment / procedure | R-454C (A2L, 14°F glide) | R-455A (A2L, 22°F glide) | | --- | --- | --- | | Manifold gauge rating | 500-800 PSI | 500-800 PSI | | Recovery cylinder | Yellow with red stripe (A2L) | Yellow with red stripe (A2L) | | Lubricant | POE | POE (same family) | | Curve selection for superheat | Dew curve at suction pressure | Dew curve at suction pressure | | Curve selection for subcooling | Bubble curve at discharge pressure | Bubble curve at discharge pressure | | Charge by weight | Required | Required (fractionation concern with 3-component blend) | | Top-off charging | Not recommended | Strongly not recommended (fractionation risk) | | Compressor motor | Sealed per UL 60335-2-89 | Sealed per UL 60335-2-89 | | Vacuum target | 500 microns held 30+ min | 500 microns held 30+ min |
The fractionation concern is real for R-455A. Charging the system with vapor from a partially-emptied cylinder draws preferentially from the higher-pressure components (R-744, R-32), shifting the remaining cylinder composition toward R-1234yf-rich. Subsequent charging draws progressively shifted composition. Always charge as liquid from a full cylinder, or recover and recharge by weight from a fresh container.
R-454C vs R-455A — competing A2L low-GWP choices
R-454C and R-455A occupy the same regulatory niche (A2L, GWP 148, commercial refrigeration) with different chemistry trade-offs. The choice between them is typically driven by OEM equipment optimization and supply-chain preferences rather than refrigerant-level differentiation.
| Property | R-454C | R-455A | | --- | --- | --- | | Composition | R-32/R-1234yf 21.5/78.5 | R-744/R-32/R-1234yf 3/21.5/75.5 | | GWP (AR5) | 148 | 148 | | Glide @ 70°F | ≈14°F | ≈22°F | | Bubble pressure @ 70°F | 141 PSIG | 170 PSIG (~20% higher) | | Volumetric capacity | Baseline | ~5-10% higher than R-454C | | Trade names | Chemours Opteon XL20 | Honeywell Solstice L40X / N40 | | Service complexity | Moderate (14°F glide) | Higher (22°F glide, fractionation) | | Equipment OEM preference | Common in EU commercial refrigeration | Adopted by Honeywell-aligned OEMs |
R-454C is operationally simpler; R-455A offers slightly more capacity per equipment displacement. Both are valid A2L low-GWP commercial refrigeration refrigerants; equipment OEM specification determines which one is in any given installation.
How to think about R-455A in 2026 and beyond
R-455A is one of the two dominant A2L low-GWP commercial refrigeration refrigerants in 2026, alongside R-454C. The 148 GWP provides structural regulatory compliance under EU F-Gas 150-GWP threshold and EPA AIM Act commercial refrigeration provisions [eufgas][aimact].
For new commercial refrigeration equipment, R-455A is a natural choice when slightly higher capacity per compressor displacement justifies the more difficult service handling. Walk-in freezers, refrigerated cases, and ice machines all see R-455A deployment, particularly in Honeywell-aligned OEM equipment lines.
For technicians, R-455A work requires the most careful glide handling of any commercial refrigerant. The 22°F bubble/dew spread is large enough that wrong-curve measurement produces meaningful charging errors. Equipment-OEM training programs cover the curve-selection discipline explicitly, and modern digital manifold gauges and PT calculators handle the selection automatically when R-455A is specified.
For R-404A retrofit decisions, R-455A is NOT the answer — A2L safety class change requires equipment-level redesign. Use R-448A or R-449A for retrofit; specify R-455A for new equipment.
Frequently asked
›What is the normal operating pressure of R-455A?
Slightly higher than R-454C due to the R-744 component. At 70°F R-455A saturation is approximately 170 PSIG bubble / 121 PSIG dew (CoolProp 7.2.0). Compare to R-454C at 70°F (141 PSIG bubble / 112 PSIG dew) — R-455A bubble is ~20% higher.
For low-temperature commercial refrigeration at −20°F evaporator, R-455A saturation is approximately 11 PSIG dew. For medium-temp at 30°F evaporator, approximately 67 PSIG dew. The wider glide produces a larger spread between bubble and dew at any given temperature.
›Why does R-455A have such large glide (22°F)?
Because the three components have widely different boiling points: R-744 (CO₂) at −109°F, R-32 at −61°F, R-1234yf at −21°F — an 88°F range across pure components. The 3/21.5/75.5 mass blend inherits a temperature glide of approximately 22°F at typical operating pressures.
The glide is the trade-off for the unique capacity benefit of the R-744 component combined with very-low GWP. R-455A delivers slightly higher volumetric capacity than R-454C (the binary alternative) because of the high-pressure CO₂ contribution, at the cost of more difficult service measurement due to the wider glide.
›What's the difference between R-455A and R-454C?
Both are A2L low-GWP commercial refrigeration blends with GWP 148. R-454C is binary (R-32/R-1234yf 21.5/78.5) with ~14°F glide. R-455A is ternary (R-744/R-32/R-1234yf 3/21.5/75.5) with ~22°F glide.
R-455A's R-744 component raises the operating pressure envelope by approximately 20% and delivers slightly higher volumetric capacity. The cost is the larger glide and the fractionation concern during partial charging. R-454C is operationally simpler; R-455A delivers more capacity per compressor displacement. OEM optimization typically drives the choice.
›What lubricant does R-455A use?
Polyolester (POE) oil — same lubricant family as R-410A, R-32, and R-454C [ahri700]. Typical viscosity is ISO 32 for medium-temperature commercial refrigeration, ISO 22 or 46 for low-temperature applications.
POE is hygroscopic — pull vacuum to 500 microns and hold ≥30 minutes before charging. The R-744 component doesn't change the lubricant choice; the blend's overall behavior is determined by the 97% HFC/HFO content.
›How do I measure superheat on R-455A?
Use the dew temperature at suction pressure. R-455A's 22°F glide means using the bubble temperature would understate superheat by ~22°F — large enough to cause major charging errors. The dew curve corresponds to the suction-line state where refrigerant has fully evaporated.
Modern PT calculators handle the dew/bubble selection automatically when R-455A is selected. Manual measurement requires reading the dew column on the published R-455A PT chart with deliberate attention to the curve choice.
›Why does R-455A include the 3% R-744 component?
Volumetric capacity. R-744 (CO₂) has very high vapor pressure — at 70°F, R-744 saturation is 838 PSIG compared to R-1234yf at 73 PSIG and R-32 at 206 PSIG. Adding a small mass fraction of R-744 to the blend raises the overall vapor density at any operating condition, increasing refrigerant mass flow per unit compressor displacement and thus increasing refrigeration capacity.
The 3% R-744 fraction is a deliberate compromise — enough to meaningfully boost capacity (~5-10% above pure R-32/R-1234yf alternatives) without making the blend behave like R-744 in terms of pressure envelope or service requirements.
›Is R-455A safe to handle?
ASHRAE class A2L — mildly flammable with low burning velocity. Equipment design accommodates per UL 60335-2-89 (sealed motors, charge limits, A2L-rated leak detection in some installations) [ul60335]. Service procedures include nitrogen-purged brazing and A2L-rated leak detection.
The 3% R-744 component doesn't change the overall safety class — the blend is A2L. Treating R-455A as if it were A1 R-404A is a safety error.
›Can I retrofit R-404A to R-455A?
Not safely without OEM evaluation. R-404A equipment is A1-rated and not designed for A2L flammability. Most R-404A equipment is not authorized for A2L refrigerant retrofit. The standard R-404A retrofit path is R-448A or R-449A (both A1, GWP ~1390).
R-455A is for new equipment specifically designed for A2L operation and the very-large glide handling.
Sources & citations
- [1]ASHRAE Standard 34-2022 — Designation and Safety Classification of Refrigerants
- [2]IPCC AR5 (2014) Working Group I, Chapter 8, Table 8.A.1
- [3]EPA AIM Act — 40 CFR Part 84 Subpart B + Technology Transitions RuleFinal Rule Oct 2021, Technology Transitions Rule Oct 2023https://www.epa.gov/climate-hfcs-reduction
- [4]EU F-Gas Regulation 517/2014 (revised 2024) — Commercial refrigeration thresholds
- [5]EPA Significant New Alternatives Policy (SNAP) — R-455A acceptable for commercial refrigeration
- [6]UL 60335-2-89 / IEC 60335-2-89 — Safety standard for commercial refrigerating appliances using A2L refrigerants
- [7]ASHRAE Standard 15-2022 — A2L charge limits
- [8]CoolProp 7.2.0 (Bell, Wronski, Quoilin, Lemort 2014)
- [9]AHRI Standard 700-2019 — Specifications for Refrigerants
- [10]Honeywell Solstice L40X / N40 (R-455A) Technical Information