R-457A
Ternary HFC/HFO blend (18% R-32 / 70% R-1234yf / 12% R-152a). A2L mildly flammable; very low GWP (139). Designed as a low-GWP replacement for R-404A and R-22 in commercial refrigeration. Significant temperature glide (~12°F).
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[0.30312]&R152a[0.15916]&R1234yf[0.53772]. Operating pressure on a running system differs — see the operating-pressure references for in-use values.
R-457A PT chart PDF — printable saturation table
Looking for the R-457A 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-457A 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 | 1.9 | -2.8 | 4.7 |
| -39°F | 2.3 | -2.5 | 4.8 |
| -38°F | 2.7 | -2.1 | 4.9 |
| -37°F | 3.2 | -1.8 | 5.0 |
| -36°F | 3.6 | -1.5 | 5.1 |
| -35°F | 4.1 | -1.1 | 5.2 |
| -34°F | 4.5 | -0.8 | 5.3 |
| -33°F | 5.0 | -0.4 | 5.4 |
| -32°F | 5.5 | -0.0 | 5.5 |
| -31°F | 6.0 | 0.4 | 5.6 |
| -30°F | 6.5 | 0.8 | 5.7 |
| -29°F | 7.0 | 1.1 | 5.8 |
| -28°F | 7.5 | 1.6 | 6.0 |
| -27°F | 8.1 | 2.0 | 6.1 |
| -26°F | 8.6 | 2.4 | 6.2 |
| -25°F | 9.1 | 2.8 | 6.3 |
| -24°F | 9.7 | 3.3 | 6.4 |
| -23°F | 10.3 | 3.7 | 6.6 |
| -22°F | 10.8 | 4.2 | 6.7 |
| -21°F | 11.4 | 4.6 | 6.8 |
| -20°F | 12.0 | 5.1 | 6.9 |
| -19°F | 12.7 | 5.6 | 7.1 |
| -18°F | 13.3 | 6.1 | 7.2 |
| -17°F | 13.9 | 6.6 | 7.3 |
| -16°F | 14.6 | 7.1 | 7.5 |
| -15°F | 15.2 | 7.6 | 7.6 |
| -14°F | 15.9 | 8.2 | 7.7 |
| -13°F | 16.5 | 8.7 | 7.8 |
| -12°F | 17.2 | 9.3 | 8.0 |
| -11°F | 17.9 | 9.8 | 8.1 |
| -10°F | 18.6 | 10.4 | 8.3 |
| -9°F | 19.4 | 11.0 | 8.4 |
| -8°F | 20.1 | 11.6 | 8.6 |
| -7°F | 20.9 | 12.2 | 8.7 |
| -6°F | 21.6 | 12.8 | 8.8 |
| -5°F | 22.4 | 13.4 | 9.0 |
| -4°F | 23.2 | 14.0 | 9.1 |
| -3°F | 24.0 | 14.7 | 9.3 |
| -2°F | 24.8 | 15.3 | 9.4 |
| -1°F | 25.6 | 16.0 | 9.6 |
| 0°F | 26.4 | 16.7 | 9.8 |
| 1°F | 27.3 | 17.4 | 9.9 |
| 2°F | 28.1 | 18.1 | 10.1 |
| 3°F | 29.0 | 18.8 | 10.2 |
| 4°F | 29.9 | 19.5 | 10.4 |
| 5°F | 30.8 | 20.3 | 10.5 |
| 6°F | 31.7 | 21.0 | 10.7 |
| 7°F | 32.7 | 21.8 | 10.9 |
| 8°F | 33.6 | 22.6 | 11.1 |
| 9°F | 34.6 | 23.3 | 11.2 |
| 10°F | 35.5 | 24.1 | 11.4 |
| 11°F | 36.5 | 25.0 | 11.6 |
| 12°F | 37.5 | 25.8 | 11.7 |
| 13°F | 38.5 | 26.6 | 11.9 |
| 14°F | 39.6 | 27.5 | 12.1 |
| 15°F | 40.6 | 28.4 | 12.3 |
| 16°F | 41.7 | 29.2 | 12.4 |
| 17°F | 42.8 | 30.1 | 12.6 |
| 18°F | 43.9 | 31.1 | 12.8 |
| 19°F | 45.0 | 32.0 | 13.0 |
| 20°FMT evap target | 46.1 | 32.9 | 13.2 |
| 21°F | 47.2 | 33.9 | 13.4 |
| 22°F | 48.4 | 34.8 | 13.5 |
| 23°F | 49.6 | 35.8 | 13.7 |
| 24°F | 50.8 | 36.8 | 13.9 |
| 25°F | 52.0 | 37.8 | 14.1 |
| 26°F | 53.2 | 38.9 | 14.3 |
| 27°F | 54.4 | 39.9 | 14.5 |
| 28°F | 55.7 | 41.0 | 14.7 |
| 29°F | 56.9 | 42.0 | 14.9 |
| 30°F | 58.2 | 43.1 | 15.1 |
| 31°F | 59.5 | 44.2 | 15.3 |
| 32°FH₂O freeze | 60.9 | 45.4 | 15.5 |
| 33°F | 62.2 | 46.5 | 15.7 |
| 34°F | 63.6 | 47.7 | 15.9 |
| 35°FMT box temp | 64.9 | 48.8 | 16.1 |
| 36°F | 66.3 | 50.0 | 16.3 |
| 37°F | 67.8 | 51.2 | 16.5 |
| 38°F | 69.2 | 52.5 | 16.7 |
| 39°F | 70.6 | 53.7 | 16.9 |
| 40°F | 72.1 | 55.0 | 17.1 |
| 41°F | 73.6 | 56.2 | 17.4 |
| 42°F | 75.1 | 57.5 | 17.6 |
| 43°F | 76.6 | 58.8 | 17.8 |
| 44°F | 78.2 | 60.2 | 18.0 |
| 45°F | 79.7 | 61.5 | 18.2 |
| 46°F | 81.3 | 62.9 | 18.4 |
| 47°F | 82.9 | 64.3 | 18.7 |
| 48°F | 84.6 | 65.7 | 18.9 |
| 49°F | 86.2 | 67.1 | 19.1 |
| 50°F | 87.9 | 68.5 | 19.3 |
| 51°F | 89.5 | 70.0 | 19.5 |
| 52°F | 91.3 | 71.5 | 19.8 |
| 53°F | 93.0 | 73.0 | 20.0 |
| 54°F | 94.7 | 74.5 | 20.2 |
| 55°F | 96.5 | 76.0 | 20.5 |
| 56°F | 98.3 | 77.6 | 20.7 |
| 57°F | 100.1 | 79.2 | 20.9 |
| 58°F | 101.9 | 80.8 | 21.1 |
| 59°F | 103.8 | 82.4 | 21.4 |
| 60°F | 105.7 | 84.0 | 21.6 |
| 61°F | 107.5 | 85.7 | 21.8 |
| 62°F | 109.5 | 87.4 | 22.1 |
| 63°F | 111.4 | 89.1 | 22.3 |
| 64°F | 113.4 | 90.8 | 22.5 |
| 65°F | 115.3 | 92.6 | 22.8 |
| 66°F | 117.4 | 94.3 | 23.0 |
| 67°F | 119.4 | 96.1 | 23.3 |
| 68°F | 121.4 | 98.0 | 23.5 |
| 69°F | 123.5 | 99.8 | 23.7 |
| 70°F | 125.6 | 101.7 | 24.0 |
| 71°F | 127.7 | 103.5 | 24.2 |
| 72°F | 129.9 | 105.5 | 24.4 |
| 73°F | 132.1 | 107.4 | 24.7 |
| 74°F | 134.3 | 109.3 | 24.9 |
| 75°F | 136.5 | 111.3 | 25.2 |
| 76°F | 138.7 | 113.3 | 25.4 |
| 77°F | 141.0 | 115.3 | 25.6 |
| 78°F | 143.3 | 117.4 | 25.9 |
| 79°F | 145.6 | 119.5 | 26.1 |
| 80°F | 147.9 | 121.6 | 26.4 |
| 81°F | 150.3 | 123.7 | 26.6 |
| 82°F | 152.7 | 125.8 | 26.8 |
| 83°F | 155.1 | 128.0 | 27.1 |
| 84°F | 157.5 | 130.2 | 27.3 |
| 85°F | 160.0 | 132.4 | 27.6 |
| 86°F | 162.5 | 134.7 | 27.8 |
| 87°F | 165.0 | 137.0 | 28.0 |
| 88°F | 167.6 | 139.3 | 28.3 |
| 89°F | 170.1 | 141.6 | 28.5 |
| 90°F | 172.7 | 143.9 | 28.8 |
| 91°F | 175.3 | 146.3 | 29.0 |
| 92°F | 178.0 | 148.7 | 29.3 |
| 93°F | 180.7 | 151.2 | 29.5 |
| 94°F | 183.4 | 153.6 | 29.7 |
| 95°FAHRI design ambient | 186.1 | 156.1 | 30.0 |
| 96°F | 188.9 | 158.7 | 30.2 |
| 97°F | 191.6 | 161.2 | 30.4 |
| 98°F | 194.5 | 163.8 | 30.7 |
| 99°F | 197.3 | 166.4 | 30.9 |
| 100°F | 200.2 | 169.0 | 31.1 |
| 101°F | 203.1 | 171.7 | 31.4 |
| 102°F | 206.0 | 174.4 | 31.6 |
| 103°F | 208.9 | 177.1 | 31.8 |
| 104°F | 211.9 | 179.9 | 32.1 |
| 105°F | 214.9 | 182.7 | 32.3 |
| 106°F | 218.0 | 185.5 | 32.5 |
| 107°F | 221.1 | 188.3 | 32.7 |
| 108°F | 224.2 | 191.2 | 33.0 |
| 109°F | 227.3 | 194.1 | 33.2 |
| 110°FCond saturation | 230.4 | 197.0 | 33.4 |
| 111°F | 233.6 | 200.0 | 33.6 |
| 112°F | 236.8 | 203.0 | 33.8 |
| 113°F | 240.1 | 206.0 | 34.1 |
| 114°F | 243.4 | 209.1 | 34.3 |
| 115°F | 246.7 | 212.2 | 34.5 |
| 116°F | 250.0 | 215.3 | 34.7 |
| 117°F | 253.4 | 218.5 | 34.9 |
| 118°F | 256.8 | 221.7 | 35.1 |
| 119°F | 260.2 | 224.9 | 35.3 |
| 120°F | 263.7 | 228.2 | 35.5 |
| 121°F | 267.2 | 231.5 | 35.7 |
| 122°F | 270.7 | 234.8 | 35.9 |
| 123°F | 274.3 | 238.2 | 36.1 |
| 124°F | 277.9 | 241.6 | 36.3 |
| 125°F | 281.5 | 245.1 | 36.4 |
| 126°F | 285.2 | 248.6 | 36.6 |
| 127°F | 288.9 | 252.1 | 36.8 |
| 128°F | 292.6 | 255.6 | 37.0 |
| 129°F | 296.4 | 259.2 | 37.1 |
| 130°F | 300.1 | 262.8 | 37.3 |
| 131°F | 304.0 | 266.5 | 37.4 |
| 132°F | 307.8 | 270.2 | 37.6 |
| 133°F | 311.7 | 273.9 | 37.8 |
| 134°F | 315.6 | 277.7 | 37.9 |
| 135°F | 319.6 | 281.6 | 38.0 |
| 136°F | 323.6 | 285.4 | 38.2 |
| 137°F | 327.6 | 289.3 | 38.3 |
| 138°F | 331.7 | 293.2 | 38.4 |
| 139°F | 335.8 | 297.2 | 38.5 |
| 140°F | 339.9 | 301.2 | 38.7 |
| 141°F | 344.1 | 305.3 | 38.8 |
| 142°F | 348.3 | 309.4 | 38.9 |
| 143°F | 352.5 | 313.6 | 39.0 |
| 144°F | 356.8 | 317.7 | 39.0 |
| 145°F | 361.1 | 322.0 | 39.1 |
| 146°F | 365.4 | 326.2 | 39.2 |
| 147°F | 369.8 | 330.6 | 39.3 |
| 148°F | 374.2 | 334.9 | 39.3 |
| 149°F | 378.7 | 339.3 | 39.4 |
| 150°F | 383.2 | 343.8 | 39.4 |
| Temp (°C) | Bubble (kPa) | Dew (kPa) | Glide (kPa) |
|---|---|---|---|
| -40°C | 13 | -19 | 32 |
| -39°C | 18 | -15 | 34 |
| -38°C | 24 | -11 | 35 |
| -37°C | 29 | -7 | 36 |
| -36°C | 35 | -2 | 37 |
| -35°C | 41 | 3 | 39 |
| -34°C | 48 | 7 | 40 |
| -33°C | 54 | 12 | 42 |
| -32°C | 61 | 18 | 43 |
| -31°C | 68 | 23 | 45 |
| -30°C | 75 | 29 | 46 |
| -29°C | 82 | 35 | 48 |
| -28°C | 90 | 41 | 49 |
| -27°C | 98 | 47 | 51 |
| -26°C | 106 | 53 | 52 |
| -25°C | 114 | 60 | 54 |
| -24°C | 123 | 67 | 56 |
| -23°C | 132 | 74 | 58 |
| -22°C | 141 | 81 | 59 |
| -21°C | 150 | 89 | 61 |
| -20°C | 160 | 97 | 63 |
| -19°C | 170 | 105 | 65 |
| -18°C | 180 | 113 | 67 |
| -17°C | 190 | 122 | 69 |
| -16°C | 201 | 131 | 71 |
| -15°C | 212 | 140 | 73 |
| -14°C | 224 | 149 | 75 |
| -13°C | 236 | 159 | 77 |
| -12°C | 248 | 169 | 79 |
| -11°C | 260 | 179 | 81 |
| -10°C | 273 | 190 | 83 |
| -9°C | 286 | 200 | 86 |
| -8°C | 299 | 212 | 88 |
| -7°CMT evap target | 313 | 223 | 90 |
| -6°C | 327 | 235 | 92 |
| -5°C | 342 | 247 | 95 |
| -4°C | 357 | 260 | 97 |
| -3°C | 372 | 272 | 99 |
| -2°C | 387 | 285 | 102 |
| -1°C | 403 | 299 | 104 |
| 0°CH₂O freeze | 420 | 313 | 107 |
| 1°C | 436 | 327 | 109 |
| 2°CMT box temp | 454 | 342 | 112 |
| 3°C | 471 | 357 | 115 |
| 4°C | 489 | 372 | 117 |
| 5°C | 507 | 388 | 120 |
| 6°C | 526 | 404 | 122 |
| 7°C | 545 | 420 | 125 |
| 8°C | 565 | 437 | 128 |
| 9°C | 585 | 455 | 130 |
| 10°C | 606 | 473 | 133 |
| 11°C | 627 | 491 | 136 |
| 12°C | 648 | 510 | 139 |
| 13°C | 670 | 529 | 142 |
| 14°C | 693 | 548 | 145 |
| 15°C | 716 | 568 | 147 |
| 16°C | 739 | 589 | 150 |
| 17°C | 763 | 610 | 153 |
| 18°C | 787 | 631 | 156 |
| 19°C | 812 | 653 | 159 |
| 20°C | 837 | 675 | 162 |
| 21°C | 863 | 698 | 165 |
| 22°C | 890 | 722 | 168 |
| 23°C | 917 | 746 | 171 |
| 24°C | 944 | 770 | 174 |
| 25°C | 972 | 795 | 177 |
| 26°C | 1,001 | 821 | 180 |
| 27°C | 1,030 | 847 | 183 |
| 28°C | 1,059 | 874 | 186 |
| 29°C | 1,090 | 901 | 189 |
| 30°C | 1,120 | 929 | 192 |
| 31°C | 1,152 | 957 | 195 |
| 32°C | 1,184 | 986 | 198 |
| 33°C | 1,216 | 1,016 | 201 |
| 34°C | 1,249 | 1,046 | 204 |
| 35°CAHRI design ambient | 1,283 | 1,077 | 207 |
| 36°C | 1,317 | 1,108 | 209 |
| 37°C | 1,352 | 1,140 | 212 |
| 38°C | 1,388 | 1,173 | 215 |
| 39°C | 1,424 | 1,206 | 218 |
| 40°C | 1,461 | 1,240 | 221 |
| 41°C | 1,499 | 1,275 | 224 |
| 42°C | 1,537 | 1,310 | 227 |
| 43°CCond saturation | 1,576 | 1,346 | 230 |
| 44°C | 1,615 | 1,383 | 232 |
| 45°C | 1,655 | 1,421 | 235 |
| 46°C | 1,696 | 1,459 | 238 |
| 47°C | 1,738 | 1,498 | 240 |
| 48°C | 1,780 | 1,538 | 243 |
| 49°C | 1,823 | 1,578 | 245 |
| 50°C | 1,867 | 1,619 | 247 |
| 51°C | 1,911 | 1,661 | 250 |
| 52°C | 1,956 | 1,704 | 252 |
| 53°C | 2,002 | 1,748 | 254 |
| 54°C | 2,049 | 1,792 | 256 |
| 55°C | 2,096 | 1,838 | 258 |
| 56°C | 2,144 | 1,884 | 260 |
| 57°C | 2,193 | 1,931 | 262 |
| 58°C | 2,242 | 1,979 | 264 |
| 59°C | 2,292 | 2,027 | 265 |
| 60°C | 2,344 | 2,077 | 267 |
| 61°C | 2,396 | 2,128 | 268 |
| 62°C | 2,448 | 2,179 | 269 |
| 63°C | 2,502 | 2,232 | 270 |
| 64°C | 2,556 | 2,285 | 271 |
| 65°C | 2,611 | 2,340 | 271 |
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-457A 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. Less commonly deployed than R-454C or R-455A but offers similar performance envelope.
Blend composition
- R-3218.0%
- R-152a12.0%
- R-1234yf70.0%
Common applications
- Commercial refrigeration (medium temp)
- R-404A retrofit option
Properties
- Boiling point (1 atm)-42.6°C / -44.7°F
- Critical pointNo single point — blend critical locus
- Molar mass87.61 g/mol
- Temperature glide12.5°F
- ODP0
- GWP (AR5, 100-yr)139
- GWP (AR6, 100-yr)156
What is R-457A?
R-457A is a ternary blend combining R-32 (HFC), R-1234yf (HFO), and R-152a (HFC). Mass composition: 18% R-32, 70% R-1234yf, 12% R-152a. All three components are mildly to moderately flammable; the blend is classified A2L (mildly flammable, low burning velocity). The very low GWP of 139 places it well below the EPA AIM Act 700-GWP threshold and meets EU F-Gas 150-GWP cutoff for commercial refrigeration.
R-457A targets the same application space as R-454C (R-32/R-1234yf 21.5/78.5, GWP 148) and R-455A (R-744/R-32/R-1234yf 3/21.5/75.5, GWP 148): low-GWP commercial refrigeration replacing R-404A. The presence of R-152a in R-457A distinguishes it — the 12% R-152a contributes capacity and reduces the GWP slightly, but also widens the temperature glide. R-457A has been less commonly deployed than R-454C in practice; manufacturers have generally standardized on R-454C and R-455A for new equipment.
Where R-457A is used
- Medium-temperature commercial refrigeration (replacing R-404A in new equipment)
- R-404A retrofit option for existing equipment with POE oil
- Some R-22 retrofit applications where low-GWP and A2L acceptability align
Regulatory & phase-down status
R-457A's GWP of 139 makes it well-positioned for the long term. It is below the EPA AIM Act 150-GWP cutoff for low-temperature commercial refrigeration (the most aggressive threshold), meaning it remains permitted for new equipment installations in that segment. The A2L classification is the limiting factor for application breadth — A2L acceptable-use designations require equipment with sealed motors, ventilation interlocks where appropriate, and explicit A2L charge limits.
Industry direction in 2025-2030: R-454C and R-455A dominate commercial refrigeration A2L; R-457A remains commercially available as an alternative but with less momentum. For very-low-GWP applications R-744 (CO₂ transcritical) competes where the equipment investment is justified.
Service notes
POE oil is required; mineral oil is incompatible. The A2L classification requires service practices appropriate for mildly flammable refrigerants: brazing requires nitrogen purge (standard practice for any HFC service anyway, but enforced strictly for A2L); leak detection requires A2L-compatible electronic detectors; recovery cylinders must be rated for the refrigerant.
R-457A has substantial temperature glide (~12.5°F per CoolProp). Superheat measurement uses the dew curve; subcooling uses the bubble curve. TXV systems generally accommodate moderate glide; very-large-glide blends (>15°F) may require adjustment. EPA Section 608 Universal or appropriate class certification covers R-457A handling.
Temperature glide
R-457A 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-457A is not currently regulated by AIM Act or EU F-Gas phase-down. Its very low GWP (139) 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-457A replaces
Frequently asked
›Why isn't R-457A as common as R-454C for R-404A replacement?
Three reasons: (1) manufacturer alignment — Honeywell and Chemours have promoted R-454C and R-455A more heavily; R-457A doesn't have the same commercial push; (2) glide differential — R-457A has slightly more glide (12.5°F) than R-454C (~10°F), which complicates TXV behavior on some equipment; (3) field availability — supply chain for R-454C is more developed. R-457A remains a valid technical choice but captures less market share.
›What's the temperature glide of R-457A?
Approximately 12.5°F (CoolProp at 0°C). This is substantial — at low evaporator setpoints (e.g., -20°F for low-temperature commercial), the bubble-to-dew temperature difference at the evaporator inlet is ~12°F, meaning the suction-line saturation temperature differs noticeably from the evaporator-inlet saturation. Use the dew curve for superheat measurement; the dew temperature at the suction pressure is the proper boundary.
›What is the GWP of R-457A?
139 per IPCC AR5, mass-weighted from R-32 (675) at 18%, R-1234yf (4) at 70%, R-152a (124) at 12%. This is below EU F-Gas 150 cutoff and EPA AIM Act 150-GWP threshold for low-temperature commercial refrigeration. It compares favorably to R-454C (148) and R-455A (148).
›Is R-457A approved for commercial refrigeration?
Yes for new equipment installations meeting A2L charge limits and equipment design requirements. EPA SNAP rules treat R-457A as acceptable for retail food refrigeration (medium-temp), commercial ice machines, and some industrial process refrigeration. R-22 and R-404A retrofit applications require the equipment to be evaluated for A2L compatibility — older A1-rated equipment is generally NOT permitted to be retrofitted to A2L without OEM approval.
›Why does R-457A include R-152a instead of going pure HFC-32/HFO-1234yf like R-454C?
R-152a addition serves two purposes: (1) capacity tuning — R-152a's vapor pressure profile is slightly different from R-1234yf's, allowing fine-tuning of the blend's capacity at specific evaporator setpoints; (2) GWP fine-tuning — R-152a (GWP 124) is lower than R-32 (GWP 675), so adding R-152a in place of some R-32 modestly reduces overall blend GWP. The tradeoff is added complexity in the blend and the slightly different flammability characteristics of R-152a (A2) vs R-32 (A2L) — in the blend the overall classification stays A2L.