R-32 PT Chart: Pressure-Temperature Table + How to Use It

Pressures below are gauge (psig) at sea-level atmosphere (14.7 psia). At altitude your gauge reads slightly higher for the same saturation condition — roughly 0.5 psi per 1,000 ft of elevation. Values come from CoolProp refrigerant property data and agree with the R-32 column on Daikin Comfort Technologies' published A1 vs. A2L Pressure Temperature Chart (chart values by Weitron) to within rounding.

Saturation temp (°F)	R-32 pressure (psig)
-20	26.8
-10	37.1
0	49.3
10	63.5
20	80.0
30	99.1
40	121.0
45	133.0
50	145.8
60	174.1
70	205.8
80	241.5
90	281.3
100	325.7
110	374.9
120	429.3
125	458.7
130	489.5

Reading it works like any single-refrigerant chart: gauge pressure in, saturation temperature out. If your manifold dial has an R-32 scale or your digital probes are set to R-32, they're doing this lookup for you — the table is the backup for when they aren't, and the sanity check for when a probe setting is wrong. For a value between rows, interpolate — the curve is smooth enough that straight-line interpolation between 10°F steps lands within a fraction of a psi.

R-32 is pure difluoromethane (CH₂F₂) — a single-component refrigerant under ASHRAE Standard 34, not a blend. A single-component refrigerant boils and condenses at one temperature for a given pressure, so its temperature glide is zero.

That matters on the gauge set. Blends like R-454B (an R-32/R-1234yf mix) evaporate and condense across a temperature range, so their charts print two columns: a bubble point (liquid) column you use for subcooling and a dew point (vapor) column you use for superheat. Grab the wrong column and your superheat or subcooling number is off by the glide.

With R-32 there is no wrong column. One saturation curve, used on both sides of the system: the same table row gives you the saturation temperature for a low-side superheat check and a high-side subcooling check.

The single curve also makes the static pressure check clean. With the system off and pressures equalized to ambient — or on a cylinder that's been sitting in the shop — pressure should match the chart at the measured temperature. A cylinder at 70°F should read about 205.8 psig. Reading noticeably higher than the chart at a known temperature points to non-condensables (air) in the system or tank.

The two calculations that justify carrying this table are standard vapor-compression practice:

Superheat (°F) = measured suction-line temperature − saturation temperature at low-side pressure

Worked example: low-side gauge reads 133 psig. The table says 133.0 psig saturates at 45°F. Your clamp probe on the suction line near the outdoor unit reads 55°F. Superheat = 55°F − 45°F = 10°F. On a fixed-orifice system, compare that against the manufacturer's superheat charging chart (it moves with outdoor dry-bulb and indoor wet-bulb). A TXV or EEV system self-regulates to roughly 8–12°F at the coil — on those, you charge by subcooling.

Subcooling (°F) = saturation temperature at liquid-line pressure − measured liquid-line temperature

Worked example: high-side gauge reads 429 psig. The table says 429.3 psig saturates at 120°F. The liquid-line probe reads 108°F. Subcooling = 120°F − 108°F = 12°F. The target is on the unit's data plate or in the install manual — charge to the plate value, not a generic rule of thumb.

Two measurement notes that wreck more readings than bad math does: strap the temperature probe to bare copper and insulate over it (an IR gun on a shiny line is not a line temperature), and let the system run at least 10–15 minutes so pressures stabilize before you trust any of it.

R-410A is a 50/50 blend of R-32 and R-125, so it's no surprise the two run close. R-32 saturates slightly higher across the whole service range — about 1 psi higher at 0°F, widening to about 12 psi at 130°F, or roughly 2%:

Temp (°F)	R-32 (psig)	R-410A (psig)
0	49.3	48.4
40	121.0	118.9
70	205.8	201.8
100	325.7	318.5
125	458.7	447.9
130	489.5	477.9

Practical read: gauges, hoses, and recovery cylinders rated for R-410A pressures cover R-32's numbers. Both use POE oil. The workflow doesn't change either — R-410A is near-azeotropic (negligible glide), so both refrigerants read off a single curve.

What does change: the chart itself (use the R-32 column, not R-410A — a 2% error compounds into a wrong superheat call), the safety class (next section), and the environmental math — R-32's GWP is 675 versus 2,088 for R-410A, which is the reason for the transition. And the obvious one that still needs saying: never top off an R-410A system with R-32 or mix the two in any circuit. Different refrigerant, different charge, full recovery first.

ASHRAE Standard 34 classifies R-32 as A2L: lower toxicity (A), lower flammability (2L — hard to ignite, low burning velocity). It is not propane-class flammable, but it's not R-410A either, and the equipment rules reflect that:

• Recovery machine — must be rated for A2L refrigerants. A legacy machine without an A2L listing is off the job.
• Leak detector — use one rated for A2Ls; verify sensitivity for R-32 specifically.
• Brazing — recover fully and flow nitrogen through the circuit before lighting a torch. That's the rule on every refrigerant; on a flammable one it's non-negotiable.
• Ventilation and ignition sources — ventilate the work area and keep sparks and open flames away from any potential release point while the circuit is open.
• Charge limits and installation rules — these come from UL 60335-2-40 and the manufacturer's installation instructions, and they vary by room size and equipment type. Follow the install manual, not habit from R-410A work.

None of this changes how you read the PT chart — the table above works exactly like the R-410A card you've used for years. It changes what's in your recovery bag.