R-454C
Zeotropic R-32/R-1234yf blend (21.5/78.5 mass) — A2L, GWP 148, ~14°F temperature glide. Low-GWP commercial refrigeration replacement for R-404A in new equipment under EPA AIM Act and EU F-Gas.
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::R32[0.37514]&R1234yf[0.62486]. Operating pressure on a running system differs — see what R-454C operating pressures should be.
R-454C PT chart PDF — printable saturation table
Looking for the R-454C 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-454C 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 | 4.3 | -1.5 | 5.8 |
| -39°F | 4.8 | -1.1 | 5.9 |
| -38°F | 5.2 | -0.8 | 6.0 |
| -37°F | 5.7 | -0.4 | 6.1 |
| -36°F | 6.2 | -0.0 | 6.3 |
| -35°F | 6.8 | 0.4 | 6.4 |
| -34°F | 7.3 | 0.8 | 6.5 |
| -33°F | 7.8 | 1.2 | 6.6 |
| -32°F | 8.3 | 1.6 | 6.8 |
| -31°F | 8.9 | 2.0 | 6.9 |
| -30°F | 9.5 | 2.4 | 7.0 |
| -29°F | 10.0 | 2.9 | 7.2 |
| -28°F | 10.6 | 3.3 | 7.3 |
| -27°F | 11.2 | 3.8 | 7.5 |
| -26°F | 11.8 | 4.2 | 7.6 |
| -25°F | 12.4 | 4.7 | 7.7 |
| -24°F | 13.1 | 5.2 | 7.9 |
| -23°F | 13.7 | 5.7 | 8.0 |
| -22°F | 14.4 | 6.2 | 8.2 |
| -21°F | 15.0 | 6.7 | 8.3 |
| -20°F | 15.7 | 7.2 | 8.5 |
| -19°F | 16.4 | 7.7 | 8.6 |
| -18°F | 17.1 | 8.3 | 8.8 |
| -17°F | 17.8 | 8.8 | 9.0 |
| -16°F | 18.5 | 9.4 | 9.1 |
| -15°F | 19.2 | 10.0 | 9.3 |
| -14°F | 20.0 | 10.5 | 9.4 |
| -13°F | 20.7 | 11.1 | 9.6 |
| -12°F | 21.5 | 11.7 | 9.8 |
| -11°F | 22.3 | 12.3 | 9.9 |
| -10°F | 23.1 | 13.0 | 10.1 |
| -9°F | 23.9 | 13.6 | 10.3 |
| -8°F | 24.7 | 14.3 | 10.5 |
| -7°F | 25.6 | 14.9 | 10.6 |
| -6°F | 26.4 | 15.6 | 10.8 |
| -5°F | 27.3 | 16.3 | 11.0 |
| -4°F | 28.1 | 17.0 | 11.2 |
| -3°F | 29.0 | 17.7 | 11.3 |
| -2°F | 29.9 | 18.4 | 11.5 |
| -1°F | 30.8 | 19.1 | 11.7 |
| 0°F | 31.8 | 19.9 | 11.9 |
| 1°F | 32.7 | 20.6 | 12.1 |
| 2°F | 33.7 | 21.4 | 12.3 |
| 3°F | 34.7 | 22.2 | 12.5 |
| 4°F | 35.6 | 23.0 | 12.7 |
| 5°F | 36.6 | 23.8 | 12.9 |
| 6°F | 37.7 | 24.6 | 13.1 |
| 7°F | 38.7 | 25.4 | 13.3 |
| 8°F | 39.8 | 26.3 | 13.5 |
| 9°F | 40.8 | 27.1 | 13.7 |
| 10°F | 41.9 | 28.0 | 13.9 |
| 11°F | 43.0 | 28.9 | 14.1 |
| 12°F | 44.1 | 29.8 | 14.3 |
| 13°F | 45.3 | 30.7 | 14.5 |
| 14°F | 46.4 | 31.6 | 14.7 |
| 15°F | 47.5 | 32.6 | 14.9 |
| 16°F | 48.7 | 33.6 | 15.2 |
| 17°F | 49.9 | 34.5 | 15.4 |
| 18°F | 51.1 | 35.5 | 15.6 |
| 19°F | 52.4 | 36.5 | 15.8 |
| 20°FMT evap target | 53.6 | 37.6 | 16.1 |
| 21°F | 54.9 | 38.6 | 16.3 |
| 22°F | 56.2 | 39.7 | 16.5 |
| 23°F | 57.5 | 40.7 | 16.7 |
| 24°F | 58.8 | 41.8 | 17.0 |
| 25°F | 60.1 | 42.9 | 17.2 |
| 26°F | 61.5 | 44.0 | 17.4 |
| 27°F | 62.8 | 45.2 | 17.7 |
| 28°F | 64.2 | 46.3 | 17.9 |
| 29°F | 65.6 | 47.5 | 18.1 |
| 30°F | 67.1 | 48.7 | 18.4 |
| 31°F | 68.5 | 49.9 | 18.6 |
| 32°FH₂O freeze | 70.0 | 51.1 | 18.9 |
| 33°F | 71.5 | 52.3 | 19.1 |
| 34°F | 73.0 | 53.6 | 19.4 |
| 35°FMT box temp | 74.5 | 54.9 | 19.6 |
| 36°F | 76.0 | 56.2 | 19.8 |
| 37°F | 77.6 | 57.5 | 20.1 |
| 38°F | 79.2 | 58.8 | 20.3 |
| 39°F | 80.8 | 60.2 | 20.6 |
| 40°F | 82.4 | 61.5 | 20.9 |
| 41°F | 84.0 | 62.9 | 21.1 |
| 42°F | 85.7 | 64.3 | 21.4 |
| 43°F | 87.4 | 65.7 | 21.6 |
| 44°F | 89.1 | 67.2 | 21.9 |
| 45°F | 90.8 | 68.6 | 22.2 |
| 46°F | 92.5 | 70.1 | 22.4 |
| 47°F | 94.3 | 71.6 | 22.7 |
| 48°F | 96.1 | 73.2 | 22.9 |
| 49°F | 97.9 | 74.7 | 23.2 |
| 50°F | 99.7 | 76.3 | 23.5 |
| 51°F | 101.6 | 77.8 | 23.7 |
| 52°F | 103.5 | 79.5 | 24.0 |
| 53°F | 105.4 | 81.1 | 24.3 |
| 54°F | 107.3 | 82.7 | 24.5 |
| 55°F | 109.2 | 84.4 | 24.8 |
| 56°F | 111.2 | 86.1 | 25.1 |
| 57°F | 113.2 | 87.8 | 25.4 |
| 58°F | 115.2 | 89.5 | 25.6 |
| 59°F | 117.2 | 91.3 | 25.9 |
| 60°F | 119.3 | 93.1 | 26.2 |
| 61°F | 121.4 | 94.9 | 26.5 |
| 62°F | 123.5 | 96.7 | 26.8 |
| 63°F | 125.6 | 98.6 | 27.0 |
| 64°F | 127.7 | 100.4 | 27.3 |
| 65°F | 129.9 | 102.3 | 27.6 |
| 66°F | 132.1 | 104.3 | 27.9 |
| 67°F | 134.3 | 106.2 | 28.2 |
| 68°F | 136.6 | 108.2 | 28.4 |
| 69°F | 138.9 | 110.2 | 28.7 |
| 70°F | 141.2 | 112.2 | 29.0 |
| 71°F | 143.5 | 114.2 | 29.3 |
| 72°F | 145.8 | 116.3 | 29.6 |
| 73°F | 148.2 | 118.4 | 29.9 |
| 74°F | 150.6 | 120.5 | 30.1 |
| 75°F | 153.0 | 122.6 | 30.4 |
| 76°F | 155.5 | 124.8 | 30.7 |
| 77°F | 158.0 | 127.0 | 31.0 |
| 78°F | 160.5 | 129.2 | 31.3 |
| 79°F | 163.0 | 131.4 | 31.6 |
| 80°F | 165.6 | 133.7 | 31.8 |
| 81°F | 168.2 | 136.0 | 32.1 |
| 82°F | 170.8 | 138.3 | 32.4 |
| 83°F | 173.4 | 140.7 | 32.7 |
| 84°F | 176.1 | 143.1 | 33.0 |
| 85°F | 178.8 | 145.5 | 33.3 |
| 86°F | 181.5 | 147.9 | 33.5 |
| 87°F | 184.2 | 150.4 | 33.8 |
| 88°F | 187.0 | 152.9 | 34.1 |
| 89°F | 189.8 | 155.4 | 34.4 |
| 90°F | 192.6 | 158.0 | 34.7 |
| 91°F | 195.5 | 160.6 | 34.9 |
| 92°F | 198.4 | 163.2 | 35.2 |
| 93°F | 201.3 | 165.8 | 35.5 |
| 94°F | 204.2 | 168.5 | 35.8 |
| 95°FAHRI design ambient | 207.2 | 171.2 | 36.0 |
| 96°F | 210.2 | 173.9 | 36.3 |
| 97°F | 213.3 | 176.7 | 36.6 |
| 98°F | 216.3 | 179.5 | 36.8 |
| 99°F | 219.4 | 182.3 | 37.1 |
| 100°F | 222.5 | 185.2 | 37.4 |
| 101°F | 225.7 | 188.0 | 37.7 |
| 102°F | 228.9 | 191.0 | 37.9 |
| 103°F | 232.1 | 193.9 | 38.2 |
| 104°F | 235.3 | 196.9 | 38.5 |
| 105°F | 238.6 | 199.9 | 38.7 |
| 106°F | 241.9 | 203.0 | 39.0 |
| 107°F | 245.3 | 206.1 | 39.2 |
| 108°F | 248.6 | 209.2 | 39.5 |
| 109°F | 252.0 | 212.3 | 39.7 |
| 110°FCond saturation | 255.5 | 215.5 | 40.0 |
| 111°F | 258.9 | 218.7 | 40.2 |
| 112°F | 262.4 | 222.0 | 40.4 |
| 113°F | 265.9 | 225.3 | 40.7 |
| 114°F | 269.5 | 228.6 | 40.9 |
| 115°F | 273.1 | 232.0 | 41.1 |
| 116°F | 276.7 | 235.4 | 41.4 |
| 117°F | 280.4 | 238.8 | 41.6 |
| 118°F | 284.1 | 242.3 | 41.8 |
| 119°F | 287.8 | 245.8 | 42.0 |
| 120°F | 291.6 | 249.3 | 42.2 |
| 121°F | 295.3 | 252.9 | 42.4 |
| 122°F | 299.2 | 256.6 | 42.6 |
| 123°F | 303.0 | 260.2 | 42.8 |
| 124°F | 306.9 | 263.9 | 43.0 |
| 125°F | 310.8 | 267.7 | 43.2 |
| 126°F | 314.8 | 271.4 | 43.4 |
| 127°F | 318.8 | 275.3 | 43.5 |
| 128°F | 322.8 | 279.1 | 43.7 |
| 129°F | 326.9 | 283.0 | 43.9 |
| 130°F | 331.0 | 287.0 | 44.0 |
| 131°F | 335.1 | 291.0 | 44.1 |
| 132°F | 339.3 | 295.0 | 44.3 |
| 133°F | 343.5 | 299.1 | 44.4 |
| 134°F | 347.7 | 303.2 | 44.6 |
| 135°F | 352.0 | 307.3 | 44.7 |
| 136°F | 356.3 | 311.6 | 44.8 |
| 137°F | 360.7 | 315.8 | 44.9 |
| 138°F | 365.1 | 320.1 | 45.0 |
| 139°F | 369.5 | 324.4 | 45.1 |
| 140°F | 373.9 | 328.8 | 45.1 |
| 141°F | 378.4 | 333.2 | 45.2 |
| 142°F | 383.0 | 337.7 | 45.2 |
| 143°F | 387.5 | 342.3 | 45.3 |
| 144°F | 392.1 | 346.8 | 45.3 |
| 145°F | 396.8 | 351.4 | 45.3 |
| 146°F | 401.5 | 356.1 | 45.3 |
| 147°F | 406.2 | 360.9 | 45.3 |
| 148°F | 410.9 | 365.6 | 45.3 |
| 149°F | 415.7 | 370.4 | 45.3 |
| 150°F | 420.6 | 375.3 | 45.2 |
| Temp (°C) | Bubble (kPa) | Dew (kPa) | Glide (kPa) |
|---|---|---|---|
| -40°C | 30 | -10 | 40 |
| -39°C | 35 | -6 | 41 |
| -38°C | 42 | -1 | 43 |
| -37°C | 48 | 4 | 44 |
| -36°C | 55 | 9 | 46 |
| -35°C | 61 | 14 | 48 |
| -34°C | 68 | 19 | 49 |
| -33°C | 76 | 25 | 51 |
| -32°C | 83 | 30 | 53 |
| -31°C | 91 | 36 | 55 |
| -30°C | 99 | 43 | 56 |
| -29°C | 107 | 49 | 58 |
| -28°C | 116 | 56 | 60 |
| -27°C | 125 | 62 | 62 |
| -26°C | 134 | 70 | 64 |
| -25°C | 143 | 77 | 66 |
| -24°C | 153 | 84 | 68 |
| -23°C | 163 | 92 | 70 |
| -22°C | 173 | 100 | 73 |
| -21°C | 183 | 108 | 75 |
| -20°C | 194 | 117 | 77 |
| -19°C | 205 | 126 | 79 |
| -18°C | 217 | 135 | 82 |
| -17°C | 228 | 144 | 84 |
| -16°C | 240 | 154 | 86 |
| -15°C | 253 | 164 | 89 |
| -14°C | 265 | 174 | 91 |
| -13°C | 279 | 185 | 94 |
| -12°C | 292 | 196 | 96 |
| -11°C | 306 | 207 | 99 |
| -10°C | 320 | 218 | 102 |
| -9°C | 334 | 230 | 104 |
| -8°C | 349 | 242 | 107 |
| -7°CMT evap target | 365 | 255 | 110 |
| -6°C | 380 | 268 | 113 |
| -5°C | 396 | 281 | 115 |
| -4°C | 413 | 294 | 118 |
| -3°C | 429 | 308 | 121 |
| -2°C | 447 | 323 | 124 |
| -1°C | 464 | 337 | 127 |
| 0°CH₂O freeze | 482 | 352 | 130 |
| 1°C | 501 | 368 | 133 |
| 2°CMT box temp | 520 | 384 | 136 |
| 3°C | 539 | 400 | 139 |
| 4°C | 559 | 417 | 142 |
| 5°C | 579 | 434 | 146 |
| 6°C | 600 | 451 | 149 |
| 7°C | 621 | 469 | 152 |
| 8°C | 643 | 488 | 155 |
| 9°C | 665 | 507 | 158 |
| 10°C | 688 | 526 | 162 |
| 11°C | 711 | 546 | 165 |
| 12°C | 734 | 566 | 169 |
| 13°C | 759 | 587 | 172 |
| 14°C | 783 | 608 | 175 |
| 15°C | 808 | 630 | 179 |
| 16°C | 834 | 652 | 182 |
| 17°C | 860 | 674 | 186 |
| 18°C | 887 | 698 | 189 |
| 19°C | 914 | 721 | 193 |
| 20°C | 942 | 746 | 196 |
| 21°C | 970 | 771 | 200 |
| 22°C | 999 | 796 | 203 |
| 23°C | 1,029 | 822 | 207 |
| 24°C | 1,059 | 848 | 210 |
| 25°C | 1,089 | 876 | 214 |
| 26°C | 1,120 | 903 | 217 |
| 27°C | 1,152 | 932 | 221 |
| 28°C | 1,185 | 960 | 224 |
| 29°C | 1,218 | 990 | 228 |
| 30°C | 1,251 | 1,020 | 231 |
| 31°C | 1,285 | 1,051 | 235 |
| 32°C | 1,320 | 1,082 | 238 |
| 33°C | 1,356 | 1,114 | 242 |
| 34°C | 1,392 | 1,147 | 245 |
| 35°CAHRI design ambient | 1,429 | 1,180 | 249 |
| 36°C | 1,466 | 1,214 | 252 |
| 37°C | 1,504 | 1,249 | 255 |
| 38°C | 1,543 | 1,285 | 259 |
| 39°C | 1,582 | 1,321 | 262 |
| 40°C | 1,623 | 1,358 | 265 |
| 41°C | 1,663 | 1,395 | 268 |
| 42°C | 1,705 | 1,434 | 271 |
| 43°CCond saturation | 1,747 | 1,473 | 274 |
| 44°C | 1,790 | 1,513 | 277 |
| 45°C | 1,834 | 1,553 | 280 |
| 46°C | 1,878 | 1,595 | 283 |
| 47°C | 1,923 | 1,637 | 286 |
| 48°C | 1,969 | 1,680 | 289 |
| 49°C | 2,015 | 1,724 | 291 |
| 50°C | 2,063 | 1,769 | 294 |
| 51°C | 2,111 | 1,815 | 296 |
| 52°C | 2,160 | 1,861 | 298 |
| 53°C | 2,209 | 1,909 | 301 |
| 54°C | 2,259 | 1,957 | 303 |
| 55°C | 2,311 | 2,006 | 305 |
| 56°C | 2,363 | 2,056 | 306 |
| 57°C | 2,415 | 2,108 | 308 |
| 58°C | 2,469 | 2,160 | 309 |
| 59°C | 2,523 | 2,213 | 310 |
| 60°C | 2,578 | 2,267 | 311 |
| 61°C | 2,634 | 2,322 | 312 |
| 62°C | 2,691 | 2,379 | 312 |
| 63°C | 2,749 | 2,436 | 313 |
| 64°C | 2,807 | 2,495 | 312 |
| 65°C | 2,866 | 2,554 | 312 |
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-454C 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 for stationary refrigeration. Targeted at low/medium-temp commercial refrigeration.
Blend composition
- R-3221.5%
- R-1234yf78.5%
Trade names
- Opteon XL20Chemours
Common applications
- Commercial refrigeration (low and medium temp)
- Supermarket cases
- R-404A retrofit
- Heat pumps
Properties
- Boiling point (1 atm)-45.6°C / -50.0°F
- Critical point186.2°F at 612 PSIG
- Molar mass90.78 g/mol
- Temperature glide13.9°F
- ODP0
- GWP (AR5, 100-yr)148
- GWP (AR6, 100-yr)167
What is R-454C?
R-454C is a zeotropic blend of 21.5% R-32 (HFC) and 78.5% R-1234yf (HFO) by mass [ashrae34]. The high R-1234yf content (GWP 4) pulls the blend's overall GWP down to 148 — below the EU F-Gas 150-GWP threshold for some commercial refrigeration categories and well below the EPA AIM Act 700-GWP threshold.
The defining trade-off vs R-404A is the safety class change from A1 to A2L (mildly flammable) and a significant temperature glide of approximately 14°F. The glide requires careful service measurement (dew curve for superheat, bubble for subcooling) and constrains the application to TXV systems rather than fixed-orifice metering devices.
Where R-454C 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 with managed A2L charge
- R-404A replacement in new equipment installations under EU F-Gas 150-GWP cap
Regulatory & phase-down status
R-454C is one of the dominant low-GWP A2L blends for new commercial refrigeration equipment under EPA AIM Act and EU F-Gas Regulation. GWP 148 sits below the EU F-Gas 150-GWP threshold for several commercial refrigeration categories and provides comfortable headroom under the EPA AIM Act 700-GWP threshold [eufgas][aimact].
Long-term regulatory positioning is strong. The 148 GWP figure was deliberately engineered to fit just under the EU 150-GWP cap — providing structural compliance for the foreseeable regulatory horizon.
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 14°F temperature glide significantly affects superheat and subcooling measurement. Use dew temperature for superheat math (suction line) and bubble temperature for subcooling (liquid line). Single-curve approximation introduces measurement error equal to the glide — for R-454C this is large enough to invalidate charging decisions on systems where superheat or subcooling targets are tight.
Temperature glide
R-454C 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-454C 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-454C replaces
Reading the R-454C PT chart — bubble and dew matter
R-454C is a zeotropic blend with significant temperature glide (~14°F at typical operating pressures), so the PT chart shows two distinct curves: bubble (saturated liquid line) and dew (saturated vapor line). Reading the chart requires selecting the correct curve for the measurement you're making.
For suction-line superheat measurement, use the dew curve. The dew temperature at the measured suction pressure is the saturation reference — superheat = suction line temperature − dew temperature. Using the bubble curve instead would understate superheat by approximately the glide (~14°F), leading to overcharging.
For liquid-line subcooling measurement, use the bubble curve. The bubble temperature at the measured discharge pressure is the saturation reference — subcooling = bubble temperature − liquid line temperature. Using the dew curve instead would overstate subcooling by the glide.
This is not a trivial correction. Typical commercial refrigeration superheat targets are 10-20°F. A 14°F glide-induced error would either show no superheat (when actual is 14°F target) or show 28°F superheat (when actual is 14°F target). Charging decisions made against the wrong curve produce substantially wrong charge amounts. Use the correct curve.
The 21.5/78.5 R-32/R-1234yf composition hits GWP 148
R-454C combines two refrigerants to engineer a specific GWP target. R-32 (HFC, GWP 675, A2L) provides capacity; R-1234yf (HFO, GWP 4, A2L) dilutes the GWP. The mass-weighted GWP arithmetic: 0.215 × 675 + 0.785 × 4 = 145 + 3 = 148 [ipccar5].
The 148 figure was engineered specifically to sit below the EU F-Gas 150-GWP threshold for several commercial refrigeration categories. R-455A (the alternative A2L low-GWP blend) hits 148 GWP through a different composition (R-744/R-32/R-1234yf 3/21.5/75.5). Both target the same regulatory threshold.
A common misconception: blending R-32 (A2L) with R-1234yf (A2L) might somehow yield A1. It doesn't — both components are mildly flammable individually, so the blend is A2L. This differs from R-410A (R-32/R-125 50/50) where R-125 (A1) was used specifically to suppress R-32's flammability and yield an A1 blend. R-454C and R-455A accept the A2L classification as the price of very-low GWP.
Pressure envelope similar to R-404A but with much wider bubble/dew spread
R-454C's bubble pressure envelope tracks R-404A within 5-10% across the operating range. At 70°F R-454C bubble is 141 PSIG vs R-404A's 148 PSIG (CoolProp 7.2.0). At 95°F, R-454C bubble is approximately 220 PSIG vs R-404A's 232 PSIG. Standard 500-800 PSI manifold gauges handle the envelope.
The operational difference is the wide bubble/dew spread. R-404A is near-azeotropic with ~1°F glide; R-454C has ~14°F glide. At 70°F R-454C bubble is 141 PSIG / dew is 112 PSIG — a 29 PSI spread. This affects equipment design (TXV systems required, fixed-orifice not well-suited) and service measurement (dew vs bubble curve selection matters).
For service technicians transitioning from R-404A practice to R-454C, the pressure-envelope adjustment is small but the glide-handling adjustment is significant. Equipment-OEM training programs for new R-454C commercial refrigeration cover the dew/bubble distinction explicitly.
GWP 148 — below EU F-Gas 150 threshold, well below EPA AIM Act 700
R-454C's GWP of 148 was engineered to fit just below the EU F-Gas Regulation 150-GWP threshold for several commercial refrigeration categories [eufgas]. The threshold targets new equipment in plug-in commercial refrigerators and freezers, multi-pack centralized refrigeration systems, and some other commercial refrigeration applications under the 2014 regulation and 2024 amendments.
Under the EPA AIM Act, R-454C clears the 700-GWP threshold for residential AC (R-454C isn't widely used in residential AC anyway) and is below the higher thresholds applied to most commercial refrigeration categories [aimact]. The 148 figure provides comfortable regulatory headroom for the foreseeable future.
The very-low GWP comes with the A2L flammability trade-off and the wide-glide zeotropic behavior. R-454C is not a drop-in for legacy A1 R-404A equipment — it requires new equipment specifically designed for A2L safety per UL 60335-2-89.
Reading R-454C at commercial refrigeration service temperatures
R-454C is most useful at sub-freezing evaporator temperatures typical of commercial refrigeration. Saturation values (bubble / dew where glide is meaningful):
- −40°F (deep freezer) — bubble approximately 5 inHg vac / dew approximately 9 inHg vac.
- −20°F (frozen food) — bubble approximately 11 PSIG / dew approximately 7 PSIG.
- 0°F (freezer) — bubble approximately 33 PSIG / dew approximately 27 PSIG.
- 30°F (refrigerated case) — bubble approximately 70 PSIG / dew approximately 60 PSIG.
- 70°F (bench reference) — bubble 141 PSIG / dew 112 PSIG.
- 95°F (summer condensing) — bubble approximately 220 PSIG / dew approximately 185 PSIG.
For service measurement: use dew for superheat (suction line); use bubble for subcooling (liquid line). The site's PT calculators and superheat/subcooling calculators handle this automatically when R-454C is selected.
A2L equipment requirements per UL 60335-2-89
R-454C commercial refrigeration equipment is designed under UL 60335-2-89 / IEC 60335-2-89 — the A2L-specific safety standard for commercial refrigerating appliances. The standard specifies sealed motor design, charge limits scaled to the enclosed space, refrigerant leak detection in some installations, and emergency ventilation interlocks [ul60335].
| Equipment / procedure | R-404A (A1) | R-454C (A2L) | | --- | --- | --- | | Manifold gauge rating | 500-800 PSI | 500-800 PSI | | Recovery cylinder | Standard 600 PSI | Yellow with red stripe (A2L marker) | | Compressor motor | Standard hermetic | Sealed motor in refrigerant circuit per UL 60335-2-89 | | Charge limits | None (A1) | Scaled to served space per UL 60335-2-89 | | Leak detection | Optional | Required in some installations | | Brazing during service | Nitrogen purge standard | Nitrogen purge mandatory; no open flames near system | | Lubricant | POE | POE (same family) | | Vacuum target | 500 microns held 30+ min | 500 microns held 30+ min | | Metering device | TXV or fixed-orifice | TXV strongly preferred (glide handling) |
The transition from R-404A service practice to R-454C is the equipment design generation gap — new R-454C equipment was designed from the start with A2L provisions; legacy R-404A equipment cannot be retrofitted to A2L safely without complete redesign.
R-454C in the commercial refrigeration phase-down trajectory
R-454C occupies a specific position in the commercial refrigeration GWP transition. The trajectory: R-502 (CFC azeotrope, banned 1996) → R-404A (HFC blend, dominant 1995-2020, A1, GWP 3922, AIM Act phase-down 2024-2025) → R-448A/R-449A (A1 HFC retrofit, GWP ~1390) → R-454C/R-455A (A2L, GWP 148) → R-744 (CO₂, GWP 1, supermarket-scale).
R-454C and R-455A serve the new-equipment niche between A1 HFC retrofits (R-448A/R-449A) and R-744 transcritical (supermarket scale). For small-to-medium commercial refrigeration installations where R-744's equipment cost is unjustified and A2L safety design is acceptable, R-454C and R-455A are the dominant choices.
Market adoption is faster in EU (where F-Gas 150-GWP thresholds drive aggressive new-equipment requirements) than US (where AIM Act provisions are more gradual). EU commercial refrigeration OEMs (Carrier Commercial Refrigeration, Hussmann, AHT Cooling Systems) ship R-454C and R-455A extensively; US adoption is growing through 2024-2027.
How to think about R-454C in 2026 and beyond
R-454C is the dominant low-GWP A2L choice for new commercial refrigeration equipment in the AIM Act and EU F-Gas regulatory environment. The 148 GWP provides structural regulatory compliance; the A2L safety class requires equipment-design accommodation but is widely supported by modern commercial refrigeration OEMs.
For new equipment specification, R-454C is a natural choice for medium-to-large self-contained commercial refrigeration (walk-in freezers, refrigerated cases, ice machines) where R-744 transcritical's equipment cost is unjustified. R-455A is the alternative A2L low-GWP blend with a slightly different glide profile and the R-744 small-fraction component for capacity tuning.
For technicians, R-454C work resembles R-404A work but with two adjustments: A2L procedures (sealed motors, leak detection, charge limits, no open flames) and zeotropic blend handling (dew vs bubble curve selection for superheat and subcooling). Equipment-OEM training programs through 2024-2027 cover both adjustments explicitly.
For R-404A retrofit decisions, R-454C is NOT the right answer — the A2L safety class change requires equipment-level redesign. Use R-448A or R-449A (A1, GWP ~1390) for R-404A retrofit; specify R-454C for new equipment.
Frequently asked
›What is the normal operating pressure of R-454C?
Lower than R-404A across the operating range. At 70°F R-454C saturation is approximately 141 PSIG bubble / 112 PSIG dew (CoolProp 7.2.0). Compare to R-404A at 70°F (148 PSIG, near-azeotropic) — R-454C bubble is slightly lower, but the wide bubble/dew spread is the operational distinction.
For low-temperature commercial refrigeration at −20°F evaporator, R-454C saturation is approximately 7 PSIG dew. For medium-temp at 30°F evaporator, approximately 50 PSIG dew. The dew curve is the correct reference for evaporator outlet conditions.
›Why does R-454C have such large glide?
Because R-32 (component, NBP −61°F) and R-1234yf (component, NBP −21°F) have very different boiling points — a 40°F spread between pure components. The 21.5/78.5 blend inherits a temperature glide of approximately 14°F at typical operating pressures, which is the difference between the temperature at which the first vapor bubble forms (bubble point) and the temperature at which the last liquid drop disappears (dew point) at the same pressure.
The glide is engineered as part of the GWP-vs-flammability balance. R-1234yf is needed in high mass fraction to keep GWP under 150; R-32 is needed in moderate mass fraction for capacity. The composition constraint produces the wide glide.
›What does R-454C's GWP of 148 mean?
A 1 kg release of R-454C traps approximately 148 times more heat than 1 kg of CO₂ over 100 years (IPCC AR5, mass-weighted from 21.5% R-32 × 675 + 78.5% R-1234yf × 4) [ipccar5]. The 148 figure sits below the EU F-Gas 150-GWP threshold for several commercial refrigeration categories and well below the EPA AIM Act 700-GWP threshold for residential AC.
For context: R-454C has 27× lower GWP per kg than R-404A (3922), the legacy refrigerant it replaces in low-temperature commercial refrigeration.
›Can I retrofit R-404A to R-454C?
Not safely without OEM evaluation. R-404A equipment is A1-rated (no flammability accommodations); R-454C is A2L and requires equipment-level safety design per UL 60335-2-89. 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) — preserves the safety class while reducing GWP. R-454C is for new equipment specifically designed for A2L operation.
›What lubricant does R-454C use?
Polyolester (POE) oil — same lubricant family as R-410A, R-32, and R-404A [ahri700]. Typical viscosity is ISO 32 for medium-temperature commercial refrigeration, ISO 22 or 46 for low-temperature applications. Verify against equipment OEM specification.
POE oil is hygroscopic — pull vacuum to 500 microns and hold ≥30 minutes before charging.
›How do I measure superheat on R-454C?
Use the dew temperature at suction pressure. R-454C's 14°F glide means using the bubble temperature would understate superheat by ~14°F — large enough to cause significant charging errors. The dew curve corresponds to the suction-line state where refrigerant has fully evaporated.
Most modern PT calculators and digital manifold gauges handle this automatically when R-454C is selected. Manual measurement requires reading the dew column on a published R-454C PT chart.
›Is R-454C safe to handle?
ASHRAE class A2L — mildly flammable with low burning velocity. A2L equipment design (sealed motors, leak detection in some installations, charge limits per UL 60335-2-89) mitigates the flammability risk to acceptable levels for commercial refrigeration [ul60335][ashrae15]. Service procedures include nitrogen-purged brazing and A2L-rated leak detection.
Treating R-454C as if it were A1 R-404A is a safety error — A2L equipment design and procedures are required.
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-454C 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]Chemours Opteon XL20 (R-454C) Product Data
- [11]Honeywell Solstice 454C Technical Information