The r32 pressure temperature chart catches most technicians off guard the first time they use it: at 5°C evaporating temperature, R32 sits at roughly 8.7 bar, noticeably lower than what R410A produces at the same condition. That gap matters when you’re standing in front of a unit with gauges, trying to decide if the system is undercharged or just running normally. Get the chart wrong and you’ll chase a ghost fault for an hour.
R32 is pure difluoromethane, nothing blended. That distinction changes how you read the chart, because R410A is a near-azeotropic mix of R32 and R125, and even with a tiny glide (around 0.1 K), you still have to account for it when a system is partially charged. With R32 you don’t. One temperature, one pressure, no ambiguity anywhere on the saturation curve.
Its GWP of 675 is roughly a third of R410A’s 2088, which is why manufacturers have been switching hard since about 2018. The boiling point at atmospheric pressure is -51.7°C, so it’s a gas at room temperature and wants to stay that way. Liquid withdrawal is standard practice for charging R32 systems, and that trips up technicians used to older refrigerants.
What the R32 PT Chart Shows
The saturation curve covers every pressure and temperature combination where R32 is changing phase. Below the curve it’s liquid, above it’s vapour, and on the line itself both phases coexist. The r32 pressure temperature chart runs from well below -50°C up to the critical point at 78.1°C and 57.8 bar, past which there’s no distinction between liquid and vapour and refrigeration simply stops working. You won’t get near that in normal operation, but it’s useful context when you’re interpreting high-side readings on a hot day.
Because R32 is a pure substance, superheat and subcooling readings are clean. If your low-side gauge reads 8.7 bar and the suction line temperature is 12°C, you have roughly 7 K of superheat. That’s a real number you can act on, no correction factors, no blend adjustments.
One thing worth knowing: R32 runs at higher discharge temperatures than R410A for identical conditions, sometimes 10-15°C higher. That’s thermodynamics, not a fault. Seeing 90°C on the discharge line doesn’t automatically mean trouble. Check the manufacturer’s limit (often around 120°C) before you start adjusting anything.
Key Pressure Temperature Values
Here are the reference points I come back to most often in the field. Memorise the evaporating and condensing values and you’ll catch most faults quickly without pulling out a full table.
| Temperature (°C) | Saturation Pressure (bar) | Typical Duty |
|---|---|---|
| -10 | 5.8 | Cold climate evaporating |
| 0 | 7.2 | Low evaporating reference |
| 5 | 8.7 | Standard evaporating (cooling) |
| 15 | 12.6 | Suction with superheat approx. |
| 40 | 21.7 | Moderate condensing |
| 45 | 24.4 | Standard condensing (cooling) |
| 55 | 30.2 | High ambient condensing |
The 45°C condensing figure of 24.4 bar is your anchor for hot-day diagnostics. If high-side pressure climbs past 27-28 bar and ambient is only 35°C, something is restricting heat rejection: dirty coil, failed fan, non-condensables. R32’s critical pressure of 57.8 bar gives you headroom, but pushing past 30 bar in normal operation is a sign something’s wrong.
On the low side, seeing below 6 bar at a 5°C design evaporating condition usually means the system is short on charge or the expansion device is restricting flow. R32 is charged by weight only, never by pressure alone, so weigh what comes out before deciding how much to add.
Reading the Chart on the Job
In practice, I use the r32 pressure temperature chart as a sanity check before touching anything. Connect the manifold, let pressures stabilise with the system running, then cross-reference both high and low side against the chart. The evaporating temperature you calculate from low-side pressure should land within a few degrees of what the indoor coil sensor shows. If it’s off by more than 5 K, start asking why.
Superheat target for most split systems is 5-8 K at the evaporator outlet, though some inverter units specify lower. Subcooling at the liquid line is usually 3-8 K. Near-zero subcooling suggests undercharge or a struggling condenser, while 15 K or more points to a blockage upstream of the expansion valve or an overcharge condition.
Discharge superheat is where R32 needs attention. Calculate it as discharge temperature minus condensing temperature from the chart. Anything under 20 K suggests liquid is reaching the compressor; anything over 50 K on a warm day might indicate low suction pressure or a metering issue. R32’s higher discharge temperatures mean your infrared thermometer will read hotter than you’re used to, so rely on the chart, not your gut.
I’m genuinely uncertain about one thing: not all manifold gauge sets sold for R410A service are rated for R32, even though the pressures are lower. R32 has different material compatibility requirements with certain elastomers, so check hose and gauge ratings before using old equipment.
Getting Comfortable With R32 Numbers
The r32 pressure temperature chart becomes second nature after a few dozen jobs. The key shift is accepting that lower low-side pressures are normal, higher discharge temperatures are normal, and single-component behaviour actually makes diagnosis cleaner than working with blended refrigerants. Print the table above and keep it in your van until the numbers stick. Once you know that 8.7 bar means 5°C and 24.4 bar means 45°C, you’ve got the anchors for the vast majority of calls you’ll see.
FAQs
What is the pressure of R32 at 0°C?
R32 saturation pressure at 0°C is approximately 7.2 bar. Use this as your low-end evaporating reference in cool weather or when diagnosing low-load conditions.
Is R32 pressure higher than R410A?
No. R32 runs at lower pressures than R410A at equivalent temperatures, which is one reason older R410A gauges can physically handle R32 service, though material compatibility still needs checking.
What is the superheat target for R32 systems?
Most manufacturers specify 5-8 K evaporator superheat for R32 splits. Always confirm against the specific unit’s datasheet, as inverter models sometimes target lower values.
