R-500 PT Chart and Refrigerant Profile

Where you will find R-500

R-500 is an azeotrope of 73.8% R-12 and 26.2% R-152a. It behaves like a single refrigerant. A-Gas lists its uses as commercial air conditioning and some dehumidifier applications. BITZER gives an application range of about 50°F down to -22°F (+10 to -30°C).

Every R-500 system you meet is old equipment. It was sold as Freon 500 (DuPont, now Chemours), Genetron 500 (Honeywell) and Forane 500 (Arkema), per A-Gas. The legacy cylinder color assigned in AHRI Guideline N-2017 was yellow. Containers packaged since 2020 are light green-gray for every refrigerant, so read the label.

Many R-500 systems have been converted. Look for a retrofit tag naming R-409A, R-401B or R-134a before you trust the original nameplate. If the readings do not fit the nameplate refrigerant, identify it first; the refrigerant identification guide covers how.

Charging R-500

Accuracy first. This site computes the R-500 table from an open mixture model. Against the National Refrigerants chart, the only independent published reference found, it reads 0.5 to 1.7 psi high, and the gap grows with temperature. The largest difference is 1.7 psi at 100°F. Use the manufacturer’s PT chart or the equipment charging data when you set a charge. The spot check is listed under “How this chart was computed” below.

As an azeotrope, R-500 has essentially no glide: the bubble and dew columns are the same for field purposes. It barely fractionates, though suppliers generally recommend charging blends as liquid. Weigh in the nameplate charge where one is given and follow the equipment maker’s method. On a TXV system, charge by subcooling to the manufacturer’s target with the subcooling calculator.

Do not read R-500 on an R-12 chart. The R-152a share changes the pressure curve.

Oil and compatibility

BITZER lists mineral oil and alkylbenzene for R-500, the same oil family as R-12. Use the oil and viscosity the compressor manufacturer specifies.

The oil decides the retrofit path. Arkema recommends R-409A for most stationary R-12 and R-500 retrofits; BITZER lists R-409A with mineral oil or AB, so the oil family stays the same. Arkema says R-134a works for many R-12 and R-500 retrofits and should be the choice for flooded evaporators, but it requires POE oil. The refrigerant oil types guide explains why mineral oil and R-134a do not mix.

Never top off R-500 with a substitute. The mix matches no chart.

Safety, handling and recovery

R-500 is ASHRAE class A1: lower toxicity, no flame propagation. It is an ozone-depleting refrigerant with an ODP of 0.738, from its CFC-12 content (40 CFR 82 Appendix A). Knowingly venting it is prohibited, recovery is required, and sales are restricted to certified technicians.

40 CFR 82.152 names R-500 as an example of a medium-pressure refrigerant. Small appliances (factory-sealed, 5 lb or less) need Type I certification; other equipment needs Type II; Universal covers both.

For appliances made before Nov 15 1993, 40 CFR 82.156 Table 1 sets separate levels; check it against the build date. Appliances with 50 lb or more fall under the ODS leak-repair rules in 40 CFR 82.157. Recovered R-500 cannot be sold to a new owner unless an EPA-certified reclaimer has reclaimed it.

Status and replacements

R-500 contains CFC-12, a Class I substance. US production and import of Class I CFCs have been banned since Jan 1 1996 under 40 CFR 82.4, apart from narrow exemptions. Running and servicing an existing system is legal with recovered, recycled, reclaimed or stockpiled refrigerant. A-Gas still lists R-500 in 30, 125, 1,000 and 1,750 lb sizes.

Because it contains HFC-152a, R-500 is technically a blend containing an AIM Act regulated substance, but EPA’s basis counts only that share (32.5). The practical limit is CFC supply.

Retrofit options with published charge guidance:

• R-409A: Arkema gives 80-90% of the R-500 charge weight, liquid phase only: 80% for cap tubes, 85-90% for TXVs.
• R-134a: Arkema gives 90-95% of the original weight, liquid or vapor, with a change to POE.
• R-401B: DuPont’s ART-36 says an R-500 system needs about 105% of the R-500 charge, starting at 100%.

R-409A and R-401B are HCFC blends with their own shrinking supply. The R-12 vs R-134a comparison covers the R-134a conversion steps, and the R-134a replacement guide covers lower-GWP options.

Common questions

What is R-500 refrigerant made of?

R-12 and R-152a, 73.8% and 26.2% by mass, per ASHRAE 34. The blend is an azeotrope, so it boils at a single temperature like a pure refrigerant.

What can replace R-500?

Arkema recommends R-409A for most stationary retrofits and R-134a for many others, including flooded evaporators. DuPont also listed R-401B for R-500 systems. Each needs its own charge and, for R-134a, POE oil.