HVAC PT ChartsVerified saturation data · 61 refrigerants
RefrigerantASHRAE R-502

R-502

A1Non-flammableHCFC Production banned · 1996
R-22/R-115 (48.8/51.2)

Historical azeotropic blend of R-22 (HCFC) and R-115 (CFC), 48.8/51.2 by mass. ASHRAE A1, ODP 0.221, GWP 4657. Production banned in 1996 under the Montreal Protocol because the R-115 component is a CFC. Was the dominant low-temperature commercial refrigerant for three decades.

Saturation @ 70°F
133.9PSIG
GWP (IPCC AR5)
4657100-yr
Temperature glide
≈0°F
Boiling point
-48.6°F
R-502 PT calculator Superheat
A1
Non-flammable

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.

01

Saturation pressure-temperature curve

Pressure
Temperature
°F
70°F: 133.9 PSIG
Quick lookup — R-502
133.9PSIG(923 kPa)
Range: -40 to 150°FOpen full PT calculator →
Common service temperatures
32°F
66PSIG
Freezing
45°F
86PSIG
Heat-pump heat
70°F
134PSIG
Standard
75°F
145PSIG
Test ref
80°F
157PSIG
Warm
95°F
197PSIG
Summer peak

Saturation values from CoolProp 7.2.0 R502.mix. Operating pressure on a running system differs — see the operating-pressure references for in-use values.

02

R-502 PT chart PDF — printable saturation table

Looking for the R-502 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-502 PT Chart — Pressure-Temperature Saturation Table

1° increments · Source: CoolProp 7.2.0 / manufacturer datasheet · hvacptcharts.com

R-502 · 1° increments · °F / PSIG
Tinted rows: 32°F H₂O freeze
R-502 pressure-temperature saturation table in Fahrenheit and PSIG
Temp (°F)Pressure (PSIG)
-40°F3.6
-39°F4.0
-38°F4.5
-37°F5.0
-36°F5.4
-35°F5.9
-34°F6.4
-33°F6.9
-32°F7.5
-31°F8.0
-30°F8.5
-29°F9.1
-28°F9.6
-27°F10.2
-26°F10.8
-25°F11.4
-24°F12.0
-23°F12.6
-22°F13.2
-21°F13.8
-20°F14.5
-19°F15.1
-18°F15.8
-17°F16.4
-16°F17.1
-15°F17.8
-14°F18.5
-13°F19.3
-12°F20.0
-11°F20.7
-10°F21.5
-9°F22.3
-8°F23.1
-7°F23.9
-6°F24.6
-5°F25.5
-4°F26.3
-3°F27.1
-2°F28.0
-1°F28.9
0°F29.8
1°F30.7
2°F31.6
3°F32.5
4°F33.5
5°F34.4
6°F35.4
7°F36.4
8°F37.4
9°F38.4
10°F39.4
11°F40.5
12°F41.5
13°F42.6
14°F43.7
15°F44.8
16°F45.9
17°F47.0
18°F48.2
19°F49.4
20°F50.6
21°F51.8
22°F53.0
23°F54.2
24°F55.5
25°F56.7
26°F58.0
27°F59.3
28°F60.6
29°F62.0
30°F63.3
31°F64.7
32°FH₂O freeze66.1
33°F67.5
34°F69.0
35°F70.4
36°F71.9
37°F73.3
38°F74.9
39°F76.4
40°F77.9
41°F79.5
42°F81.1
43°F82.7
44°F84.3
45°F85.9
46°F87.6
47°F89.3
48°F91.0
49°F92.7
50°F94.4
51°F96.2
52°F98.0
53°F99.8
54°F101.6
55°F103.5
56°F105.3
57°F107.2
58°F109.2
59°F111.1
60°F113.1
61°F115.0
62°F117.0
63°F119.1
64°F121.1
65°F123.2
66°F125.3
67°F127.4
68°F129.6
69°F131.7
70°F133.9
71°F136.2
72°F138.4
73°F140.7
74°F142.9
75°F145.3
76°F147.6
77°F150.0
78°F152.4
79°F154.8
80°F157.2
81°F159.7
82°F162.2
83°F164.7
84°F167.3
85°F169.8
86°F172.4
87°F175.1
88°F177.7
89°F180.4
90°F183.1
91°F185.9
92°F188.6
93°F191.4
94°F194.3
95°F197.1
96°F200.0
97°F202.9
98°F205.8
99°F208.8
100°F211.8
101°F214.8
102°F217.9
103°F221.0
104°F224.1
105°F227.2
106°F230.4
107°F233.6
108°F236.9
109°F240.2
110°F243.5
111°F246.8
112°F250.2
113°F253.6
114°F257.0
115°F260.5
116°F264.0
117°F267.5
118°F271.1
119°F274.7
120°F278.3
121°F282.0
122°F285.7
123°F289.4
124°F293.2
125°F297.0
126°F300.9
127°F304.7
128°F308.7
129°F312.6
130°F316.6
131°F320.6
132°F324.7
133°F328.8
134°F332.9
135°F337.1
136°F341.3
137°F345.6
138°F349.9
139°F354.2
140°F358.6
141°F363.0
142°F367.5
143°F372.0
144°F376.5
145°F381.1
146°F385.7
147°F390.4
148°F395.1
149°F399.8
150°F404.6
CoolProp 7.2.0 · PSIG/kPa = gauge · PSIA = PSIG + 14.696 · kPa(abs) = kPa(gauge) + 101.325

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-502 PT chart data: CoolProp 7.2.0 (REFPROP-compatible Helmholtz EOS) or manufacturer datasheet, validated against AHRI Standard 700-2019.

03

At a glance

Chemistry

R-22/R-115 (48.8/51.2)
Azeotropic HCFC/CFC blend

Lubricant compatibility

MOABPOE

Azeotrope with no glide. Historically the dominant low-temperature commercial refrigerant for supermarkets. Banned because R-115 is a CFC.

Blend composition

  • R-2248.8%
  • R-11551.2%

Common applications

  • Low-temperature commercial refrigeration (legacy)
  • Supermarket frozen food cases (legacy)
04

Properties

  • Boiling point (1 atm)
    -44.8°C / -48.6°F
  • Critical point
    No single point — blend critical locus
  • Molar mass
    111.63 g/mol
  • Temperature glide
    Negligible (-0.29°F)
  • ODP
    0.221
  • GWP (AR5, 100-yr)
    4657
05

What is R-502?

R-502 is an azeotropic blend of R-22 (chlorodifluoromethane, HCFC) and R-115 (chloropentafluoroethane, CFC) in 48.8/51.2 mass ratio. The R-115 component carries the chlorofluorocarbon liability — its production was banned in the United States on January 1, 1996 under the Montreal Protocol CFC phase-out. As a CFC-containing blend, R-502 was banned alongside pure CFCs even though its bulk is the HCFC R-22.

From the 1960s through the mid-1990s, R-502 was the dominant refrigerant in low-temperature commercial refrigeration — supermarket frozen food cases, walk-in freezers, ice machines, and industrial process cooling. R-22 alone has inadequate capacity at low evaporator setpoints (below -10°F) for the compressor displacement available in that era's equipment; R-502's azeotropic blend provided both the capacity and the discharge-temperature suppression needed for reliable low-temperature operation. The discharge-temperature reduction was important — R-22 alone produces very high compressor discharge temperatures at low-temp setpoints, reducing compressor life.

Where R-502 is used

  • Supermarket low-temperature commercial refrigeration (legacy, pre-1996)
  • Walk-in freezers and frozen food cases (legacy)
  • Commercial ice machines (legacy)
  • Industrial process cooling at low-temperature setpoints (legacy)
  • No new equipment since 1996; reclaimed supply for diminishing legacy equipment

Regulatory & phase-down status

R-502 production has been banned in the United States for almost three decades. The vast majority of R-502 equipment has aged out through normal replacement cycles — typical commercial refrigeration equipment life is 15-20 years, so equipment installed before 1996 is now mostly retired. The remaining R-502 equipment in service is at the long-tail end of legacy installations.

For any remaining R-502 equipment, the retrofit refrigerants are R-422A (HFC, mineral-oil-compatible, A1, GWP 3143), R-404A (HFC, POE-oil, A1, GWP 3922) historically, and more recently R-448A, R-449A, R-454C, R-455A as low-GWP options. R-422A retrofit is the easiest because mineral oil stays in the system; for low-GWP modern equipment, full replacement is typical.

Service notes

Mineral oil (MO) and alkylbenzene (AB) are compatible. POE is NOT used with R-502 in original equipment. EPA Section 608 Type II certification covers R-502 handling; recovery is required.

R-502 is azeotropic (glide ~0.3°F per CoolProp at 0°C) — effectively a single-fluid refrigerant with no bubble/dew distinction needed for superheat or subcooling measurement. This was the original design intent — R-502 was developed to give the capacity of a blend with the service simplicity of a pure refrigerant.

07

Operating cycle

CompressorRaises pressureCondenserRejects heat to outdoorsExpansion deviceDrops pressureEvaporatorAbsorbs heat from indoorsDischarge: 243 PSIG, 180°FLiquid: 243 PSIG, 100°FEvap inlet: 78 PSIG, 40°F (two-phase)Suction: 78 PSIG, 50°FTypical residential cooling cycle for R-502 (40°F evap, 110°F condenser, 10°F superheat, 10°F subcooling)
08

Phase-down timeline

19962000200520102015202020252028today (2026-06-05)
1996-01-01
US production banned (Montreal Protocol)
Regulatory timeline for R-502
09

Global warming potential, in context

No peer-comparison group is defined for R-502. Its 100-year GWP per IPCC AR5 is 4657 — above the EPA AIM Act 700 GWP cap and well above the EU F-Gas 150 cap.

Peer-comparison groups are defined for refrigerants that compete in the same application sector (residential AC, commercial MT/LT, chillers, mobile AC). Specialty or research-grade refrigerants without a clear peer set don't appear in any group; their GWP is shown above in absolute terms instead.

10

Retrofit and replacement paths

Replacements for R-502

11

Frequently asked

›What was R-502 used for?

Low-temperature commercial refrigeration was the dominant application: supermarket frozen food cases, walk-in freezers, commercial ice machines, and industrial process cooling at sub-zero (°F) evaporator setpoints. R-502 displaced R-22 at low-temp because R-22's discharge temperature at low evaporator settings was too high for reliable compressor operation, and R-502's blend chemistry tamed that — giving capacity AND lower discharge temperature.

›Why was R-502 banned?

The R-115 component (chloropentafluoroethane, 51.2% of R-502) is a chlorofluorocarbon — CClF₂CF₃. R-115's ODP is 0.6, contributing the bulk of R-502's 0.221 blend ODP. The Montreal Protocol mandated CFC phase-out; the US implemented the production ban on January 1, 1996. R-502 was banned because of the R-115 component, even though most of the molecule by mass is HCFC R-22 (which was banned later, in 2020, for its own ODP).

›What replaced R-502 in modern equipment?

The succession: (1) initially R-404A and R-507A (HFC blends, A1, GWP ~3900) replaced R-502 in new equipment from the late 1990s through ~2015; (2) R-448A and R-449A (HFC blends, A1, lower GWP ~1300-1400) took over as AIM Act and SNAP pressure increased; (3) for new equipment from 2024 onward, R-454C, R-455A, and R-744 (CO₂ transcritical) are the low-GWP A2L/A1 options.

›Can I retrofit R-502 equipment to R-404A?

Yes, with oil change. R-502 uses mineral oil; R-404A requires POE oil. Retrofit procedure: recover R-502; flush oil (often requiring multiple oil changes due to mineral oil residue in compressor); install POE oil; replace filter-drier; pull vacuum to 500 microns; charge R-404A by weight. Verify TXV operation. R-422A is a simpler retrofit (keeps mineral oil) but has higher GWP than R-448A or R-449A modern options. Full equipment replacement is often the practical choice given the age of remaining R-502 equipment.

›Is R-502 an azeotrope or zeotrope?

Azeotrope (or near-azeotrope). R-502 has minimal temperature glide (~0.3°F) at typical operating pressures — bubble and dew points are essentially coincident. The 48.8/51.2 composition was chosen specifically to produce azeotropic behavior, allowing R-502 to be handled like a pure refrigerant in service. This service simplicity was a major commercial advantage compared to zeotropic blends like R-407C that came later.

›What is the GWP of R-502?

4657 per IPCC AR5, mass-weighted from R-22 (1810) at 48.8% and R-115 (7370) at 51.2%. The high GWP is dominated by R-115. Combined with the 0.221 ODP, R-502 was unviable in modern regulatory environments regardless of which constraint applied first.

Download this dataset

Full PT chart for R-502 · CC BY 4.0 · attribute the source

CSV JSON

Data sources & provenance

PT chart
CoolProp 7.2.0 R502.mix
Cross-checked against
CoolProp 7.2.0 (R502.mix); ASHRAE Handbook of Refrigeration 2022
Properties
CoolProp 7.2.0 + ASHRAE Standard 34-2022
GWP
IPCC AR5 Table 8.A.1 (composition-weighted)
Generated
2026-06-05

Reference material. Always verify pressure values against the equipment data plate and manufacturer service literature before charging or troubleshooting a specific system. Saturation pressure differs from operating pressure — see superheat & subcooling fundamentals.