R-32 PT Chart (Pressure-Temperature)

Why does an R-32 chart have only one pressure column?

Because R-32 is one molecule, not a mixture. A pure refrigerant boils and condenses at the same temperature for a given pressure, so the bubble point and the dew point are identical. There's no glide to account for, and you use the same number whether you're working out superheat on the suction line or subcooling on the liquid line.

That also makes the field side simpler than a blend. A slow leak can't fractionate R-32, so after the leak is repaired the remaining charge is still R-32. Follow the manufacturer's charging and recovery instructions all the same, since A2L handling rules apply.

R-32 vs. R-410A and R-454B pressures

Is R-32 flammable? What A2L means

Yes, mildly. R-32 carries the ASHRAE safety class A2L: A for lower toxicity, 2L for lower flammability. ASHRAE Standard 34 defines 2L as a maximum burning velocity of 10 cm/s or less, tested at 23°C and 101.3 kPa. It's harder to ignite and burns more slowly than a class 2 or 3 refrigerant, but it isn't nonflammable like R-22 or R-410A (both A1).

• EPA status: EPA SNAP lists R-32 as acceptable with use conditions for new residential and light commercial AC and heat pumps, with a GWP of 675 and an ozone depletion potential of 0. The listings are in Federal Register rules dated April 10, 2015, May 6, 2021 and April 28, 2023.
• New equipment only: use R-32 in equipment designed and listed for it. Don't convert an R-410A or R-22 system to R-32, and never mix refrigerants.
• Tools: recovery machines, cylinders, vacuum pumps and leak detectors should be rated for A2L refrigerants. Keep ignition sources out of the work area and ventilate before brazing.
• Install rules such as charge limits, leak detection and mitigation come from the equipment's installation instructions and your adopted codes.

Where these numbers come from

We compute the table with CoolProp 8.0.0 using its reference equation of state for pure R-32, converted to gauge pressure relative to 14.696 psia. Our tests compare 20 temperatures against the Daikin A1 vs. A2L chart and 10 against the Arkema Forane wall chart (NIST REFPROP 9.0); every point is within 0.1 psi. At 0°F we compute 49.3 psig; Daikin prints 49.2 and Arkema 49.3.