R-422A
Ternary HFC blend with hydrocarbon (85.1% R-125 / 11.5% R-134a / 3.4% R-600a). Branded as ISCEON MO79 (Chemours). ASHRAE A1, GWP 3143. Designed as a mineral-oil-compatible R-502 retrofit for low-temperature commercial refrigeration.
Lower toxicity (Occupational Exposure Limit ≥ 400 ppm). No flame propagation in air at standard atmospheric pressure and 60°C. R-134a, R-22, R-410A, R-404A, R-744 (CO2) are A1.
- Flammability
- None (no flame propagation)
- 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 R422A.mix. Operating pressure on a running system differs — see the operating-pressure references for in-use values.
R-422A PT chart PDF — printable saturation table
Looking for the R-422A 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-422A 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 | 5.4 | 3.2 | 2.2 |
| -39°F | 5.9 | 3.7 | 2.2 |
| -38°F | 6.4 | 4.2 | 2.3 |
| -37°F | 7.0 | 4.7 | 2.3 |
| -36°F | 7.5 | 5.2 | 2.3 |
| -35°F | 8.1 | 5.7 | 2.4 |
| -34°F | 8.6 | 6.2 | 2.4 |
| -33°F | 9.2 | 6.8 | 2.4 |
| -32°F | 9.8 | 7.3 | 2.5 |
| -31°F | 10.4 | 7.9 | 2.5 |
| -30°F | 11.0 | 8.4 | 2.5 |
| -29°F | 11.6 | 9.0 | 2.6 |
| -28°F | 12.2 | 9.6 | 2.6 |
| -27°F | 12.8 | 10.2 | 2.7 |
| -26°F | 13.5 | 10.8 | 2.7 |
| -25°F | 14.1 | 11.4 | 2.7 |
| -24°F | 14.8 | 12.1 | 2.8 |
| -23°F | 15.5 | 12.7 | 2.8 |
| -22°F | 16.2 | 13.4 | 2.8 |
| -21°F | 16.9 | 14.0 | 2.9 |
| -20°F | 17.6 | 14.7 | 2.9 |
| -19°F | 18.4 | 15.4 | 2.9 |
| -18°F | 19.1 | 16.1 | 3.0 |
| -17°F | 19.9 | 16.8 | 3.0 |
| -16°F | 20.6 | 17.6 | 3.1 |
| -15°F | 21.4 | 18.3 | 3.1 |
| -14°F | 22.2 | 19.1 | 3.1 |
| -13°F | 23.0 | 19.9 | 3.2 |
| -12°F | 23.9 | 20.6 | 3.2 |
| -11°F | 24.7 | 21.4 | 3.3 |
| -10°F | 25.6 | 22.3 | 3.3 |
| -9°F | 26.4 | 23.1 | 3.3 |
| -8°F | 27.3 | 23.9 | 3.4 |
| -7°F | 28.2 | 24.8 | 3.4 |
| -6°F | 29.1 | 25.6 | 3.5 |
| -5°F | 30.0 | 26.5 | 3.5 |
| -4°F | 31.0 | 27.4 | 3.5 |
| -3°F | 31.9 | 28.4 | 3.6 |
| -2°F | 32.9 | 29.3 | 3.6 |
| -1°F | 33.9 | 30.2 | 3.6 |
| 0°F | 34.9 | 31.2 | 3.7 |
| 1°F | 35.9 | 32.2 | 3.7 |
| 2°F | 36.9 | 33.1 | 3.8 |
| 3°F | 38.0 | 34.1 | 3.8 |
| 4°F | 39.0 | 35.2 | 3.9 |
| 5°F | 40.1 | 36.2 | 3.9 |
| 6°F | 41.2 | 37.3 | 3.9 |
| 7°F | 42.3 | 38.3 | 4.0 |
| 8°F | 43.5 | 39.4 | 4.0 |
| 9°F | 44.6 | 40.5 | 4.1 |
| 10°F | 45.8 | 41.6 | 4.1 |
| 11°F | 46.9 | 42.8 | 4.1 |
| 12°F | 48.1 | 44.0 | 4.2 |
| 13°F | 49.4 | 45.1 | 4.2 |
| 14°F | 50.6 | 46.3 | 4.3 |
| 15°F | 51.8 | 47.5 | 4.3 |
| 16°F | 53.1 | 48.8 | 4.4 |
| 17°F | 54.4 | 50.0 | 4.4 |
| 18°F | 55.7 | 51.3 | 4.4 |
| 19°F | 57.0 | 52.5 | 4.5 |
| 20°F | 58.4 | 53.8 | 4.5 |
| 21°F | 59.7 | 55.2 | 4.6 |
| 22°F | 61.1 | 56.5 | 4.6 |
| 23°F | 62.5 | 57.9 | 4.6 |
| 24°F | 63.9 | 59.2 | 4.7 |
| 25°F | 65.4 | 60.6 | 4.7 |
| 26°F | 66.8 | 62.0 | 4.8 |
| 27°F | 68.3 | 63.5 | 4.8 |
| 28°F | 69.8 | 64.9 | 4.9 |
| 29°F | 71.3 | 66.4 | 4.9 |
| 30°F | 72.8 | 67.9 | 4.9 |
| 31°F | 74.4 | 69.4 | 5.0 |
| 32°FH₂O freeze | 76.0 | 71.0 | 5.0 |
| 33°F | 77.6 | 72.5 | 5.1 |
| 34°F | 79.2 | 74.1 | 5.1 |
| 35°F | 80.9 | 75.7 | 5.2 |
| 36°F | 82.5 | 77.3 | 5.2 |
| 37°F | 84.2 | 79.0 | 5.2 |
| 38°F | 85.9 | 80.7 | 5.3 |
| 39°F | 87.7 | 82.3 | 5.3 |
| 40°FAC evap target | 89.4 | 84.0 | 5.4 |
| 41°F | 91.2 | 85.8 | 5.4 |
| 42°F | 93.0 | 87.5 | 5.4 |
| 43°F | 94.8 | 89.3 | 5.5 |
| 44°F | 96.6 | 91.1 | 5.5 |
| 45°F | 98.5 | 92.9 | 5.6 |
| 46°F | 100.4 | 94.8 | 5.6 |
| 47°F | 102.3 | 96.7 | 5.6 |
| 48°F | 104.2 | 98.6 | 5.7 |
| 49°F | 106.2 | 100.5 | 5.7 |
| 50°F | 108.2 | 102.4 | 5.8 |
| 51°F | 110.2 | 104.4 | 5.8 |
| 52°F | 112.2 | 106.4 | 5.8 |
| 53°F | 114.3 | 108.4 | 5.9 |
| 54°F | 116.4 | 110.5 | 5.9 |
| 55°F | 118.5 | 112.5 | 6.0 |
| 56°F | 120.6 | 114.6 | 6.0 |
| 57°F | 122.8 | 116.7 | 6.0 |
| 58°F | 124.9 | 118.9 | 6.1 |
| 59°F | 127.2 | 121.0 | 6.1 |
| 60°F | 129.4 | 123.3 | 6.1 |
| 61°F | 131.7 | 125.5 | 6.2 |
| 62°F | 133.9 | 127.7 | 6.2 |
| 63°F | 136.3 | 130.0 | 6.3 |
| 64°F | 138.6 | 132.3 | 6.3 |
| 65°F | 141.0 | 134.6 | 6.3 |
| 66°F | 143.3 | 137.0 | 6.4 |
| 67°F | 145.8 | 139.4 | 6.4 |
| 68°F | 148.2 | 141.8 | 6.4 |
| 69°F | 150.7 | 144.2 | 6.5 |
| 70°FRoom T | 153.2 | 146.7 | 6.5 |
| 71°F | 155.7 | 149.2 | 6.5 |
| 72°F | 158.3 | 151.7 | 6.6 |
| 73°F | 160.9 | 154.3 | 6.6 |
| 74°F | 163.5 | 156.9 | 6.6 |
| 75°F | 166.2 | 159.5 | 6.7 |
| 76°F | 168.8 | 162.1 | 6.7 |
| 77°F | 171.6 | 164.8 | 6.7 |
| 78°F | 174.3 | 167.5 | 6.8 |
| 79°F | 177.1 | 170.3 | 6.8 |
| 80°F | 179.8 | 173.0 | 6.8 |
| 81°F | 182.7 | 175.8 | 6.8 |
| 82°F | 185.5 | 178.7 | 6.9 |
| 83°F | 188.4 | 181.5 | 6.9 |
| 84°F | 191.3 | 184.4 | 6.9 |
| 85°F | 194.3 | 187.3 | 7.0 |
| 86°F | 197.3 | 190.3 | 7.0 |
| 87°F | 200.3 | 193.3 | 7.0 |
| 88°F | 203.3 | 196.3 | 7.0 |
| 89°F | 206.4 | 199.3 | 7.1 |
| 90°F | 209.5 | 202.4 | 7.1 |
| 91°F | 212.7 | 205.6 | 7.1 |
| 92°F | 215.8 | 208.7 | 7.1 |
| 93°F | 219.0 | 211.9 | 7.2 |
| 94°F | 222.3 | 215.1 | 7.2 |
| 95°FAHRI design ambient | 225.6 | 218.4 | 7.2 |
| 96°F | 228.9 | 221.7 | 7.2 |
| 97°F | 232.2 | 225.0 | 7.2 |
| 98°F | 235.6 | 228.3 | 7.2 |
| 99°F | 239.0 | 231.7 | 7.3 |
| 100°F | 242.4 | 235.2 | 7.3 |
| 101°F | 245.9 | 238.6 | 7.3 |
| 102°F | 249.4 | 242.1 | 7.3 |
| 103°F | 253.0 | 245.7 | 7.3 |
| 104°F | 256.6 | 249.3 | 7.3 |
| 105°F | 260.2 | 252.9 | 7.3 |
| 106°F | 263.9 | 256.5 | 7.3 |
| 107°F | 267.6 | 260.2 | 7.4 |
| 108°F | 271.3 | 263.9 | 7.4 |
| 109°F | 275.1 | 267.7 | 7.4 |
| 110°FTypical cond saturation | 278.9 | 271.5 | 7.4 |
| 111°F | 282.7 | 275.3 | 7.4 |
| 112°F | 286.6 | 279.2 | 7.4 |
| 113°F | 290.5 | 283.1 | 7.4 |
| 114°F | 294.5 | 287.1 | 7.4 |
| 115°F | 298.5 | 291.1 | 7.4 |
| 116°F | 302.5 | 295.2 | 7.4 |
| 117°F | 306.6 | 299.2 | 7.4 |
| 118°F | 310.7 | 303.4 | 7.4 |
| 119°F | 314.9 | 307.5 | 7.3 |
| 120°F | 319.1 | 311.8 | 7.3 |
| 121°F | 323.3 | 316.0 | 7.3 |
| 122°F | 327.6 | 320.3 | 7.3 |
| 123°F | 331.9 | 324.6 | 7.3 |
| 124°F | 336.3 | 329.0 | 7.3 |
| 125°F | 340.7 | 333.4 | 7.3 |
| 126°F | 345.1 | 337.9 | 7.2 |
| 127°F | 349.6 | 342.4 | 7.2 |
| 128°F | 354.2 | 347.0 | 7.2 |
| 129°F | 358.8 | 351.6 | 7.1 |
| 130°F | 363.4 | 356.3 | 7.1 |
| 131°F | 368.1 | 361.0 | 7.1 |
| 132°F | 372.8 | 365.7 | 7.0 |
| 133°F | 377.5 | 370.6 | 7.0 |
| 134°F | 382.3 | 375.4 | 6.9 |
| 135°F | 387.2 | 380.3 | 6.9 |
| 136°F | 392.1 | 385.3 | 6.8 |
| 137°F | 397.0 | 390.3 | 6.8 |
| 138°F | 402.0 | 395.3 | 6.7 |
| 139°F | 407.1 | 400.4 | 6.6 |
| 140°F | 412.2 | 405.6 | 6.6 |
| 141°F | 417.3 | 410.8 | 6.5 |
| 142°F | 422.5 | 416.1 | 6.4 |
| 150°F | 466.0 | 460.6 | 5.4 |
| Temp (°C) | Bubble (kPa) | Dew (kPa) | Glide (kPa) |
|---|---|---|---|
| -40°C | 37 | 22 | 15 |
| -39°C | 44 | 28 | 15 |
| -38°C | 50 | 34 | 16 |
| -37°C | 57 | 41 | 16 |
| -36°C | 64 | 47 | 17 |
| -35°C | 71 | 54 | 17 |
| -34°C | 79 | 61 | 18 |
| -33°C | 87 | 69 | 18 |
| -32°C | 95 | 76 | 19 |
| -31°C | 103 | 84 | 19 |
| -30°C | 112 | 92 | 20 |
| -29°C | 120 | 101 | 20 |
| -28°C | 130 | 109 | 20 |
| -27°C | 139 | 118 | 21 |
| -26°C | 149 | 127 | 21 |
| -25°C | 159 | 137 | 22 |
| -24°C | 169 | 147 | 22 |
| -23°C | 180 | 157 | 23 |
| -22°C | 191 | 167 | 23 |
| -21°C | 202 | 178 | 24 |
| -20°C | 214 | 189 | 24 |
| -19°C | 225 | 201 | 25 |
| -18°C | 238 | 212 | 25 |
| -17°C | 250 | 224 | 26 |
| -16°C | 263 | 237 | 26 |
| -15°C | 277 | 250 | 27 |
| -14°C | 290 | 263 | 27 |
| -13°C | 304 | 276 | 28 |
| -12°C | 319 | 290 | 28 |
| -11°C | 334 | 305 | 29 |
| -10°C | 349 | 319 | 30 |
| -9°C | 364 | 334 | 30 |
| -8°C | 380 | 350 | 30 |
| -7°C | 397 | 366 | 31 |
| -6°C | 414 | 382 | 32 |
| -5°C | 431 | 399 | 32 |
| -4°C | 449 | 416 | 33 |
| -3°C | 467 | 434 | 33 |
| -2°C | 485 | 452 | 34 |
| -1°C | 504 | 470 | 34 |
| 0°CH₂O freeze | 524 | 489 | 35 |
| 1°C | 544 | 509 | 35 |
| 2°C | 564 | 529 | 36 |
| 3°C | 585 | 549 | 36 |
| 4°CAC evap target | 607 | 570 | 37 |
| 5°C | 629 | 591 | 37 |
| 6°C | 651 | 613 | 38 |
| 7°C | 674 | 636 | 38 |
| 8°C | 697 | 659 | 39 |
| 9°C | 721 | 682 | 39 |
| 10°C | 746 | 706 | 40 |
| 11°C | 771 | 731 | 40 |
| 12°C | 797 | 756 | 41 |
| 13°C | 823 | 782 | 41 |
| 14°C | 849 | 808 | 42 |
| 15°C | 877 | 835 | 42 |
| 16°C | 905 | 862 | 43 |
| 17°C | 933 | 890 | 43 |
| 18°C | 962 | 919 | 43 |
| 19°C | 992 | 948 | 44 |
| 20°C | 1,022 | 978 | 44 |
| 21°CRoom T | 1,053 | 1,008 | 45 |
| 22°C | 1,084 | 1,039 | 45 |
| 23°C | 1,117 | 1,071 | 46 |
| 24°C | 1,149 | 1,103 | 46 |
| 25°C | 1,183 | 1,136 | 46 |
| 26°C | 1,217 | 1,170 | 47 |
| 27°C | 1,252 | 1,205 | 47 |
| 28°C | 1,287 | 1,240 | 47 |
| 29°C | 1,323 | 1,275 | 48 |
| 30°C | 1,360 | 1,312 | 48 |
| 31°C | 1,398 | 1,349 | 48 |
| 32°C | 1,436 | 1,387 | 49 |
| 33°C | 1,475 | 1,426 | 49 |
| 34°C | 1,515 | 1,465 | 49 |
| 35°CAHRI design ambient | 1,555 | 1,506 | 50 |
| 36°C | 1,596 | 1,547 | 50 |
| 37°C | 1,638 | 1,588 | 50 |
| 38°C | 1,681 | 1,631 | 50 |
| 39°C | 1,725 | 1,674 | 50 |
| 40°C | 1,769 | 1,719 | 51 |
| 41°C | 1,814 | 1,764 | 51 |
| 42°C | 1,860 | 1,809 | 51 |
| 43°CTypical cond saturation | 1,907 | 1,856 | 51 |
| 44°C | 1,955 | 1,904 | 51 |
| 45°C | 2,003 | 1,952 | 51 |
| 46°C | 2,052 | 2,002 | 51 |
| 47°C | 2,103 | 2,052 | 51 |
| 48°C | 2,154 | 2,103 | 51 |
| 49°C | 2,206 | 2,155 | 51 |
| 50°C | 2,259 | 2,208 | 50 |
| 51°C | 2,313 | 2,262 | 50 |
| 52°C | 2,367 | 2,318 | 50 |
| 53°C | 2,423 | 2,374 | 50 |
| 54°C | 2,480 | 2,431 | 49 |
| 55°C | 2,538 | 2,489 | 49 |
| 56°C | 2,596 | 2,548 | 48 |
| 57°C | 2,656 | 2,609 | 48 |
| 58°C | 2,717 | 2,670 | 47 |
| 59°C | 2,779 | 2,733 | 46 |
| 60°C | 2,842 | 2,797 | 45 |
| 61°C | 2,906 | 2,862 | 44 |
| 62°C | 2,973 | 2,930 | 43 |
| 63°C | 3,040 | 2,999 | 41 |
| 64°C | 3,108 | 3,068 | 40 |
| 65°C | 3,175 | 3,137 | 38 |
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-422A 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
Mineral-oil-compatible retrofit for R-502 and R-22 low-temperature systems.
Blend composition
- R-12585.1%
- R-134a11.5%
- R-600a3.4%
Trade names
- ISCEON MO79Chemours
Common applications
- R-502 retrofit (low-temperature commercial refrigeration)
- R-22 retrofit (low-temp)
Properties
- Boiling point (1 atm)-46.7°C / -52.1°F
- Critical pointNo single point — blend critical locus
- Molar mass113.60 g/mol
- Temperature glide3.2°F
- ODP0
- GWP (AR5, 100-yr)3143
- GWP (AR6, 100-yr)3370
What is R-422A?
R-422A is a ternary blend specifically targeting R-502 retrofit. R-502 was the dominant low-temperature commercial refrigeration refrigerant from the 1960s through the 1990s — an azeotropic R-22/R-115 blend that was banned for production in 1996 (the R-115 component is a CFC). R-422A's high R-125 content (85.1%) provides the low-temperature capacity and pressure characteristics needed to match R-502 in existing equipment.
The 3.4% R-600a (isobutane) hydrocarbon component aids miscibility with the mineral oil typical of R-502 systems, allowing R-422A retrofit without the POE oil change that R-404A retrofit requires.
Where R-422A is used
- R-502 retrofit (low-temperature commercial refrigeration — the primary application)
- R-22 retrofit (low-temperature only; the R-125-dominant composition is sized for low-evap operation)
- Walk-in freezers, frozen food cases, ice machines (legacy equipment)
Regulatory & phase-down status
R-422A's GWP of 3143 is far above the EPA AIM Act 700 threshold. For new equipment R-422A is not the choice; for retrofit of legacy R-502 or R-22 low-temperature equipment it remains commercially available.
Most R-502 equipment has now been replaced through equipment-replacement cycles since the 1996 ban. The remaining R-502 retrofit market is small. For modern low-temperature commercial refrigeration, the path is R-448A, R-449A (medium-GWP retrofit), R-454C, R-455A (low-GWP A2L), R-744 (CO2 transcritical), or R-290 (propane, charge-limited).
Service notes
Compatible with mineral oil (MO), alkylbenzene (AB), and POE oils. For R-502 retrofits the existing mineral oil typically stays in the system. R-422A has small to moderate temperature glide (~3-4°F at typical low-temperature operating pressures).
Temperature glide
R-422A 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
No phase-down milestones documented for R-422A in this build. This may mean: (a) no regulatory phase-down currently published; (b) the refrigerant has local regulatory schedules not yet transcribed into the site dataset; or (c) it is a specialty refrigerant outside the main regulatory frameworks. For authoritative current status, consult the EPA AIM Act allocations (40 CFR Part 84), EU F-Gas Regulation 517/2014 + 2024/573, and the relevant national implementations of the Kigali Amendment.
Global warming potential, in context
R-22 retrofit blends
Retrofit and replacement paths
R-422A replaces
Replacements for R-422A
Frequently asked
›Why was R-502 originally banned?
R-502 is a 48.8/51.2 R-22/R-115 azeotropic blend. R-115 is a chlorofluorocarbon (CFC) with ODP 0.6 and GWP 7370 — production was banned in the US in 1996 under the Montreal Protocol CFC phase-out. R-22 alone has lower capacity at low-temperature setpoints than R-502 had, which is why R-502 was developed in the first place — and which made R-502 retrofit a service-engineering challenge when the ban took effect.
›How does R-422A compare to R-404A for low-temp commercial refrigeration?
R-404A was the new-equipment replacement for R-502 starting in the late 1990s; R-422A is the retrofit replacement for existing R-502 equipment. R-404A requires POE oil change; R-422A works with the original mineral oil. Both have similar GWP envelope (R-422A 3143, R-404A 3922). Both are now AIM-Act-restricted for new equipment. For new installations the path is R-448A, R-449A (lower-GWP A1) or R-454C, R-455A (A2L).
›What is the normal operating pressure of R-422A?
Close to R-502 across the low-temperature envelope. At a 0°F evaporator setpoint with 95°F ambient, expect roughly 22-30 PSIG suction and 250-300 PSIG discharge — within 10% of R-502's operating envelope. The match is intentional: R-422A's high R-125 content was chosen specifically to replicate R-502's low-temperature capacity in legacy equipment.
›What lubricant does R-422A use?
Compatible with mineral oil (MO), alkylbenzene (AB), and POE. For R-502 retrofits the existing mineral oil stays in the system. The 3.4% R-600a hydrocarbon component aids HFC-mineral-oil miscibility.
›Does R-422A have temperature glide?
Yes — about 3-4°F at typical low-temperature operating pressures. This is smaller than R-407C's 7°F glide or R-448A's 5°F glide, reflecting the R-125-dominant composition. Use the dew curve for superheat measurement on zeotropic blends.
›Should I use R-422A or replace the equipment?
For most remaining R-502 equipment by this point in the phase-out timeline, full equipment replacement is the better choice. The equipment is 25+ years old; expected service life is approaching end; capacity is reduced from original specification. New low-temperature commercial refrigeration equipment uses R-448A / R-449A / R-454C / R-455A / R-744 with substantially better efficiency. R-422A retrofit remains an option for specific situations where equipment replacement is impractical.
›What is the GWP of R-422A?
3143 (IPCC AR5, mass-weighted from R-125, R-134a, and R-600a components). This is comparable to R-404A's 3922 — both are high-GWP HFC blends. The R-125 component (GWP 3500) drives most of R-422A's GWP.