R-502 PT Chart and Refrigerant Profile
R-502 is an A1 CFC azeotropic blend of R-22 and R-115 (48.8/51.2 % by mass). At 40°F its vapor (dew) pressure is 77.5 psig; at 100°F its liquid (bubble) pressure is 211.8 psig.
Reviewed · PT values computed with CoolProp 8.0.0 and checked against a published chart (largest difference 4.9 psi)
Accuracy note. The open mixture model used for R-502 gives vapor (dew) pressures up to 4.9 psi below the manufacturer's published chart (at 100°F). The difference is listed in How this chart was computed. When you set a charge on R-502, use the manufacturer's chart or the equipment charging chart.
R-502 at a glance
| Safety class (ASHRAE 34) | A1: lower toxicity, no flame propagation |
|---|---|
| Type | CFC, azeotropic blend |
| Composition | R-22 48.8% · R-115 51.2% by mass |
| GWP (100-year, AR4) | 4,657 · AR5: 4,786Contains no AIM Act regulated HFC; regulated as an ozone-depleting substance (CFC-115 is Class I). |
| Ozone depletion potential | 0.334 |
| Lubricant | Mineral oil or alkylbenzene (AB) |
| Boiling point at 14.7 psia | -48.6°F bubble · -47.8°F dew |
| Critical point | 180.1°F, 588 psia |
| 40°F evaporating | 77.5 psig (dew), glide 0.3°F |
| 100°F condensing | 211.8 psig (bubble), glide 0.1°F |
| Charge as | Liquid, as suppliers recommend for blends (an azeotrope barely fractionates) |
| Typical use | Legacy low- and medium-temperature commercial refrigeration (display cases, ice machines, freezers) |
| Trade names | Freon 502 (legacy DuPont, now Chemours) |
| US status | Contains Class I CFC-115, banned from US production and import since Jan 1 1996, and HCFC-22, whose production ended in 2020; service only from recovered or stockpiled supply. |
| Replaced by | R-404A, R-507A, R-402A, R-402B, R-408A |
R-502 PT chart (°F and psig)
R-502 is a blend, so it has two saturation pressures at each temperature. Read the vapor (dew) column against suction pressure for superheat and the liquid (bubble) column against liquid-line pressure for subcooling. Tap a row to load it into the lookup.
-40°F to 150°F · psig at sea level · °C and kPa in the CSV · italic = inches Hg vacuum
| °F | Liquidbubble psig | Vapordew psig |
|---|---|---|
| -40 | 3.6 | 3.2 |
| -39 | 4.0 | 3.7 |
| -38 | 4.5 | 4.1 |
| -37 | 5.0 | 4.6 |
| -36 | 5.4 | 5.1 |
| -35 | 5.9 | 5.6 |
| -34 | 6.4 | 6.1 |
| -33 | 6.9 | 6.6 |
| -32 | 7.5 | 7.1 |
| -31 | 8.0 | 7.6 |
| -30 | 8.5 | 8.2 |
| -29 | 9.1 | 8.7 |
| -28 | 9.6 | 9.3 |
| -27 | 10.2 | 9.8 |
| -26 | 10.8 | 10.4 |
| -25 | 11.4 | 11.0 |
| -24 | 12.0 | 11.6 |
| -23 | 12.6 | 12.2 |
| -22 | 13.2 | 12.8 |
| -21 | 13.8 | 13.4 |
| -20 | 14.5 | 14.1 |
| -19 | 15.1 | 14.7 |
| -18 | 15.8 | 15.4 |
| -17 | 16.5 | 16.1 |
| -16 | 17.1 | 16.7 |
| -15 | 17.8 | 17.4 |
| -14 | 18.5 | 18.1 |
| -13 | 19.3 | 18.9 |
| -12 | 20.0 | 19.6 |
| -11 | 20.7 | 20.3 |
| -10 | 21.5 | 21.1 |
| -9 | 22.3 | 21.9 |
| -8 | 23.1 | 22.6 |
| -7 | 23.9 | 23.4 |
| -6 | 24.7 | 24.2 |
| -5 | 25.5 | 25.1 |
| -4 | 26.3 | 25.9 |
| -3 | 27.2 | 26.7 |
| -2 | 28.0 | 27.6 |
| -1 | 28.9 | 28.5 |
| 0 | 29.8 | 29.4 |
| 1 | 30.7 | 30.3 |
| 2 | 31.6 | 31.2 |
| 3 | 32.5 | 32.1 |
| 4 | 33.5 | 33.0 |
| 5 | 34.4 | 34.0 |
| 6 | 35.4 | 35.0 |
| 7 | 36.4 | 36.0 |
| 8 | 37.4 | 36.9 |
| 9 | 38.4 | 38.0 |
| 10 | 39.4 | 39.0 |
| 11 | 40.5 | 40.0 |
| 12 | 41.5 | 41.1 |
| 13 | 42.6 | 42.2 |
| 14 | 43.7 | 43.3 |
| 15 | 44.8 | 44.4 |
| 16 | 45.9 | 45.5 |
| 17 | 47.1 | 46.6 |
| 18 | 48.2 | 47.8 |
| 19 | 49.4 | 49.0 |
| 20 | 50.6 | 50.1 |
| 21 | 51.8 | 51.3 |
| 22 | 53.0 | 52.6 |
| 23 | 54.2 | 53.8 |
| 24 | 55.5 | 55.1 |
| 25 | 56.7 | 56.3 |
| 26 | 58.0 | 57.6 |
| 27 | 59.3 | 58.9 |
| 28 | 60.7 | 60.2 |
| 29 | 62.0 | 61.6 |
| 30 | 63.3 | 62.9 |
| 31 | 64.7 | 64.3 |
| 32 | 66.1 | 65.7 |
| 33 | 67.5 | 67.1 |
| 34 | 69.0 | 68.5 |
| 35 | 70.4 | 70.0 |
| 36 | 71.9 | 71.5 |
| 37 | 73.4 | 73.0 |
| 38 | 74.9 | 74.5 |
| 39 | 76.4 | 76.0 |
| 40 | 77.9 | 77.5 |
| 41 | 79.5 | 79.1 |
| 42 | 81.1 | 80.7 |
| 43 | 82.7 | 82.3 |
| 44 | 84.3 | 83.9 |
| 45 | 85.9 | 85.5 |
| 46 | 87.6 | 87.2 |
| 47 | 89.3 | 88.9 |
| 48 | 91.0 | 90.6 |
| 49 | 92.7 | 92.3 |
| 50 | 94.4 | 94.1 |
| 51 | 96.2 | 95.8 |
| 52 | 98.0 | 97.6 |
| 53 | 99.8 | 99.4 |
| 54 | 101.6 | 101.3 |
| 55 | 103.5 | 103.1 |
| 56 | 105.4 | 105.0 |
| 57 | 107.2 | 106.9 |
| 58 | 109.2 | 108.8 |
| 59 | 111.1 | 110.7 |
| 60 | 113.1 | 112.7 |
| 61 | 115.0 | 114.7 |
| 62 | 117.0 | 116.7 |
| 63 | 119.1 | 118.7 |
| 64 | 121.1 | 120.8 |
| 65 | 123.2 | 122.9 |
| 66 | 125.3 | 125.0 |
| 67 | 127.4 | 127.1 |
| 68 | 129.6 | 129.2 |
| 69 | 131.7 | 131.4 |
| 70 | 133.9 | 133.6 |
| 71 | 136.2 | 135.8 |
| 72 | 138.4 | 138.1 |
| 73 | 140.7 | 140.3 |
| 74 | 143.0 | 142.6 |
| 75 | 145.3 | 145.0 |
| 76 | 147.6 | 147.3 |
| 77 | 150.0 | 149.7 |
| 78 | 152.4 | 152.1 |
| 79 | 154.8 | 154.5 |
| 80 | 157.2 | 156.9 |
| 81 | 159.7 | 159.4 |
| 82 | 162.2 | 161.9 |
| 83 | 164.7 | 164.4 |
| 84 | 167.3 | 167.0 |
| 85 | 169.8 | 169.6 |
| 86 | 172.4 | 172.2 |
| 87 | 175.1 | 174.8 |
| 88 | 177.7 | 177.5 |
| 89 | 180.4 | 180.1 |
| 90 | 183.1 | 182.9 |
| 91 | 185.9 | 185.6 |
| 92 | 188.6 | 188.4 |
| 93 | 191.4 | 191.2 |
| 94 | 194.3 | 194.0 |
| 95 | 197.1 | 196.9 |
| 96 | 200.0 | 199.7 |
| 97 | 202.9 | 202.7 |
| 98 | 205.8 | 205.6 |
| 99 | 208.8 | 208.6 |
| 100 | 211.8 | 211.6 |
| 101 | 214.8 | 214.6 |
| 102 | 217.9 | 217.7 |
| 103 | 221.0 | 220.8 |
| 104 | 224.1 | 223.9 |
| 105 | 227.2 | 227.0 |
| 106 | 230.4 | 230.2 |
| 107 | 233.6 | 233.4 |
| 108 | 236.9 | 236.7 |
| 109 | 240.2 | 239.9 |
| 110 | 243.5 | 243.3 |
| 111 | 246.8 | 246.6 |
| 112 | 250.2 | 250.0 |
| 113 | 253.6 | 253.4 |
| 114 | 257.0 | 256.8 |
| 115 | 260.5 | 260.3 |
| 116 | 264.0 | 263.8 |
| 117 | 267.5 | 267.3 |
| 118 | 271.1 | 270.9 |
| 119 | 274.7 | 274.5 |
| 120 | 278.3 | 278.1 |
| 121 | 282.0 | 281.8 |
| 122 | 285.7 | 285.5 |
| 123 | 289.4 | 289.3 |
| 124 | 293.2 | 293.0 |
| 125 | 297.0 | 296.8 |
| 126 | 300.9 | 300.7 |
| 127 | 304.7 | 304.6 |
| 128 | 308.7 | 308.5 |
| 129 | 312.6 | 312.5 |
| 130 | 316.6 | 316.5 |
| 131 | 320.6 | 320.5 |
| 132 | 324.7 | 324.5 |
| 133 | 328.8 | 328.7 |
| 134 | 332.9 | 332.8 |
| 135 | 337.1 | 337.0 |
| 136 | 341.3 | 341.2 |
| 137 | 345.6 | 345.5 |
| 138 | 349.9 | 349.8 |
| 139 | 354.2 | 354.1 |
| 140 | 358.6 | 358.5 |
| 141 | 363.0 | 362.9 |
| 142 | 367.5 | 367.3 |
| 143 | 372.0 | 371.8 |
| 144 | 376.5 | 376.4 |
| 145 | 381.1 | 381.0 |
| 146 | 385.7 | 385.6 |
| 147 | 390.4 | 390.3 |
| 148 | 395.1 | 395.0 |
| 149 | 399.8 | 399.7 |
| 150 | 404.6 | 404.5 |
Where you will find R-502
R-502 is a legacy CFC refrigerant from low- and medium-temperature commercial refrigeration. It is an azeotrope of 48.8% R-22 and 51.2% R-115 (CFC-115). Expect it in older freezers, frozen-food and ice cream display cases, ice machines and other low- and medium-temperature commercial systems.
Check the compressor tag and system nameplate, then look for a retrofit tag. Many R-502 systems were converted to service blends (R-402A, R-402B, R-408A) or to R-404A or R-507A. The legacy R-502 cylinder color was light purple (lavender). Cylinders packaged since 2020 are light green-gray, so read the label.
Charging R-502
As an azeotrope, R-502 behaves almost like a single refrigerant: the bubble and dew columns sit nearly on top of each other, so one reading serves both sides in practice. No manufacturer charging statement for R-502 was found for this page. Follow the equipment maker’s method and charge amount; for TXV systems charge by subcooling to the manufacturer’s target with the subcooling calculator. The superheat calculator does the PT lookup for the evaporator side.
A note on this chart. No pure-fluid equation exists for R-502, so this site computes it as an R-22/R-115 mixture in CoolProp. That model reads below the National Refrigerants (NRI) reference table by about 2%. The gap is about 1 psi at low temperatures and grows to about 5 psi at condensing temperatures. Both pure-component equations match NIST, so the error comes from the estimated interaction between R-22 and R-115.
The difference is smallest on the low side. For subcooling, or any reading where a few psi matter, use the NRI R-502 reference guide or the equipment maker’s table and treat this chart as approximate. The validation table further down this page lists every compared point. For reading technique, see how to read a PT chart.
Oil and compatibility
R-502 systems ran mineral oil or alkylbenzene; BITZER lists alkylbenzene for R-502. Use the lubricant on the compressor tag.
Conversions change the oil picture. BITZER notes that the HFC replacements R-404A and R-507A require POE, so a move to either one is an oil change, not a top-off. The refrigerant oil types guide covers POE, AB and mineral oil.
Never add R-22, R-404A or a service blend to an R-502 system to make up a charge. A mixture matches no PT chart and has to be recovered as mixed refrigerant.
Safety, handling and recovery
R-502 is ASHRAE class A1: lower toxicity, no flame propagation. It is an ozone-depleting refrigerant with an ODP of 0.334, computed from the 40 CFR 82 values for its two components. CFC-115 is Class I and HCFC-22 is Class II. Knowingly venting it is prohibited, recovery is required, and sales are restricted to certified technicians.
40 CFR 82.152 names R-502 as an example of a high-pressure refrigerant, so Type II certification (or Universal) applies.
| Appliance (made on or after Nov 15 1993) | Required recovery |
|---|---|
| High-pressure, under 200 lb | 0 in Hg |
| High-pressure, 200 lb or more | 10 in Hg |
Appliances with 50 lb or more are subject to the ODS leak-repair rules in 40 CFR 82.157. Recovered R-502 cannot be sold to a new owner unless an EPA-certified reclaimer has reclaimed it (40 CFR 82.154(d)).
Status and replacements
US production and import of Class I CFCs, including CFC-115, have been banned since Jan 1 1996 (40 CFR 82.4), apart from narrow essential and critical uses. HCFC-22 production and import ended on Jan 1 2020. Servicing an existing R-502 system is still legal, but only with recovered, recycled, reclaimed or pre-1996 stockpiled refrigerant. R-502 contains no HFC, so the AIM Act phasedown does not apply to it.
The replacement paths, per BITZER:
- R-404A or R-507A, the HFC replacements, both on POE. Both are HFCs, so their supply falls under the AIM Act phasedown.
- Service blends R-402A, R-402B, R-403A/B and R-408A. Several are no longer produced, so check availability before planning around one.
Common questions
What oil does R-502 use?
Mineral oil or alkylbenzene; BITZER lists AB. Converting to R-404A or R-507A means changing to POE.
What replaced R-502?
R-404A and R-507A, per BITZER, with service blends such as R-402A, R-402B and R-408A for retrofits. Many of those service blends are no longer made.
How this chart was computed
Every pressure on this page is calculated, not copied: CoolProp 8.0.0 (HEOS backend), the open-source implementation of the reference equations of state, using the model mix:R502 at the nominal ASHRAE 34 composition. Gauge values assume sea-level air pressure (14.696 psia); kPa values in the CSV are absolute.
Spot check against National Refrigerants Refrigerant Reference Guide, 7th Edition 2020: R-502:
| °F | Column | Published | This chart | Difference |
|---|---|---|---|---|
| 0 | bubble | 45.4 psia | 44.5 psia | -0.9 psi |
| 0 | dew | 45.2 psia | 44.1 psia | -1.1 psi |
| 40 | bubble | 94.5 psia | 92.6 psia | -1.9 psi |
| 40 | dew | 94.4 psia | 92.2 psia | -2.2 psi |
| 100 | bubble | 231.3 psia | 226.5 psia | -4.8 psi |
| 100 | dew | 231.2 psia | 226.3 psia | -4.9 psi |
Mix model R-22/R-115 (Bell 2016 interaction parameters) reads 1-5 psi (about 2%) below the NRI reference, increasingly with temperature. The pure R-22 and R-115 equations match NIST exactly, so the deviation comes from the estimated R-22/R-115 interaction parameters. No better CoolProp model exists (no pseudo-pure R-502). Kept with disclosure.
Charts from different publishers can differ by a few tenths of a psi because of the equation of state and blend tolerances. Always charge to the equipment manufacturer's data. Full method and every spot check
Comparisons with R-502
Calculators for R-502
Sources
- BITZER Refrigerant Report: R-502 data bitzer.de
- BITZER Refrigerant Report: R-502 alternatives (R-404A, R-507A, POE) bitzer.de
- BITZER Refrigerant Report: R-502 service blends bitzer.de
- National Refrigerants Refrigerant Reference Guide, 7th Edition 2020: R-502 refrigerants.com
- eCFR 40 CFR 82.4: Class I production and import prohibitions ecfr.gov
- eCFR 40 CFR 82 Subpart A Appendix A: Class I controlled substances (ODP) ecfr.gov
- eCFR 40 CFR 82.152: Section 608 definitions (pressure classes) ecfr.gov
- eCFR 40 CFR 82.154: Venting prohibition and sales restriction ecfr.gov
Reviewed . Found an error? Tell us and we will correct it.
More in Legacy CFCs and R-502