R-502 PT Chart
A1 GWP 4657Azeotropic blend (R-22/R-115). CFC Blend.
⚠️ BANNED — CFC
Boiling Point
-48.6°F
-44.8°C
Critical Temp
180.1°F
82.3°C
Critical Pressure
587.9 psia
40.53 bar
About R-502
R-502 was the standard low-temperature commercial refrigerant before the CFC phase-out. It is an azeotrope of R-22 and R-115, so it contains ozone-depleting CFC, and production ended in the US in 1996. It now appears only in very old equipment, where it is usually replaced with R-404A, R-507A or an HFO blend.
Saturation pressures at typical operating points, taken from the table below:
- Freezer evaporator (−20°F): 14.5 PSIG
- Medium-temp evaporator (20°F): 50.6 PSIG
- Condensing (105°F): 227.2 PSIG
The table covers -80°F to 160°F in 5°F steps. Below about -49°F the saturation pressure is below atmospheric, so gauges read in vacuum (shown in blue in the table).
R-502 Pressure-Temperature Graph
R-502 Saturation Pressure Table
Blue values indicate vacuum (below atmospheric pressure).
| °F | °C | PSIG | PSIA | kPa | bar |
|---|---|---|---|---|---|
| -80 | -62.2 | -8.7 | 6.04 | 41.7 | 0.417 |
| -75 | -59.4 | -7.7 | 7.04 | 48.5 | 0.485 |
| -70 | -56.7 | -6.5 | 8.16 | 56.3 | 0.563 |
| -65 | -53.9 | -5.3 | 9.43 | 65.0 | 0.65 |
| -60 | -51.1 | -3.9 | 10.84 | 74.8 | 0.748 |
| -55 | -48.3 | -2.3 | 12.42 | 85.6 | 0.856 |
| -50 | -45.6 | -0.5 | 14.17 | 97.7 | 0.977 |
| -45 | -42.8 | 1.4 | 16.12 | 111.1 | 1.111 |
| -40 | -40.0 | 3.6 | 18.26 | 125.9 | 1.259 |
| -35 | -37.2 | 5.9 | 20.62 | 142.2 | 1.422 |
| -30 | -34.4 | 8.5 | 23.22 | 160.1 | 1.601 |
| -25 | -31.7 | 11.4 | 26.05 | 179.6 | 1.796 |
| -20 | -28.9 | 14.5 | 29.15 | 201.0 | 2.01 |
| -15 | -26.1 | 17.8 | 32.53 | 224.3 | 2.243 |
| -10 | -23.3 | 21.5 | 36.19 | 249.6 | 2.496 |
| -5 | -20.6 | 25.5 | 40.17 | 277.0 | 2.77 |
| 0 | -17.8 | 29.8 | 44.47 | 306.6 | 3.066 |
| 5 | -15.0 | 34.4 | 49.11 | 338.6 | 3.386 |
| 10 | -12.2 | 39.4 | 54.11 | 373.1 | 3.731 |
| 15 | -9.4 | 44.8 | 59.48 | 410.1 | 4.101 |
| 20 | -6.7 | 50.6 | 65.25 | 449.9 | 4.499 |
| 25 | -3.9 | 56.7 | 71.43 | 492.5 | 4.925 |
| 30 | -1.1 | 63.3 | 78.04 | 538.1 | 5.381 |
| 35 | 1.7 | 70.4 | 85.1 | 586.7 | 5.867 |
| 40 | 4.4 | 77.9 | 92.62 | 638.6 | 6.386 |
| 45 | 7.2 | 85.9 | 100.62 | 693.8 | 6.938 |
| 50 | 10.0 | 94.4 | 109.14 | 752.5 | 7.525 |
| 55 | 12.8 | 103.5 | 118.17 | 814.8 | 8.148 |
| 60 | 15.6 | 113.1 | 127.75 | 880.8 | 8.808 |
| 65 | 18.3 | 123.2 | 137.9 | 950.8 | 9.508 |
| 70 | 21.1 | 133.9 | 148.62 | 1024.7 | 10.247 |
| 75 | 23.9 | 145.3 | 159.96 | 1102.9 | 11.029 |
| 80 | 26.7 | 157.2 | 171.92 | 1185.4 | 11.854 |
| 85 | 29.4 | 169.8 | 184.53 | 1272.3 | 12.723 |
| 90 | 32.2 | 183.1 | 197.82 | 1363.9 | 13.639 |
| 95 | 35.0 | 197.1 | 211.8 | 1460.3 | 14.603 |
| 100 | 37.8 | 211.8 | 226.5 | 1561.6 | 15.616 |
| 105 | 40.6 | 227.2 | 241.94 | 1668.1 | 16.681 |
| 110 | 43.3 | 243.5 | 258.16 | 1779.9 | 17.799 |
| 115 | 46.1 | 260.5 | 275.17 | 1897.2 | 18.972 |
| 120 | 48.9 | 278.3 | 293.01 | 2020.2 | 20.202 |
| 125 | 51.7 | 297.0 | 311.71 | 2149.2 | 21.492 |
| 130 | 54.4 | 316.6 | 331.3 | 2284.2 | 22.842 |
| 135 | 57.2 | 337.1 | 351.82 | 2425.7 | 24.257 |
| 140 | 60.0 | 358.6 | 373.3 | 2573.8 | 25.738 |
| 145 | 62.8 | 381.1 | 395.79 | 2728.8 | 27.288 |
| 150 | 65.6 | 404.6 | 419.33 | 2891.2 | 28.912 |
| 155 | 68.3 | 429.3 | 443.99 | 3061.2 | 30.612 |
| 160 | 71.1 | 455.1 | 469.82 | 3239.3 | 32.393 |
Properties
| ASHRAE Designation | 502 |
| Safety Classification | A1 (non-flammable, low toxicity) |
| GWP (AR4, 100-yr) | 4657 |
| ODP | 0.33 |
| Molecular Weight | 111.63 g/mol |
| Boiling Point (1 atm) | -48.6°F / -44.8°C |
| Critical Temperature | 180.1°F / 82.3°C |
| Critical Pressure | 587.9 psia / 40.53 bar |
| Category | CFC Blend |
Common Applications
- Legacy low-temp refrigeration
- Legacy transport