Saturation pressure–temperature table for R134a, R404A, R410A and R448A/R449A in bar gauge from −40 °C to +60 °C, how to use PT values for superheat and subcooling, and what glide means for blends.
The table gives saturation pressure in bar(g) at sea level. For the zeotropic blends R404A, R410A and especially R448A/R449A, liquid (bubble) and vapour (dew) pressures differ; service gauges and controllers use dew point for suction-side superheat and bubble point for liquid-side subcooling. R404A and R410A have near-zero glide, so one column is given; R448A/R449A values are dew-point with the bubble point roughly 4–6 K warmer at the same pressure in the mid range.
| °C | R134a | R404A | R410A | R448A/449A (dew) |
|---|---|---|---|---|
| −40 | −0.49 | 0.33 | 0.76 | 0.28 |
| −35 | −0.34 | 0.65 | 1.22 | 0.60 |
| −30 | −0.16 | 1.04 | 1.77 | 0.98 |
| −25 | 0.06 | 1.49 | 2.43 | 1.44 |
| −20 | 0.33 | 2.03 | 3.20 | 1.98 |
| −15 | 0.64 | 2.65 | 4.11 | 2.61 |
| −10 | 1.01 | 3.36 | 5.16 | 3.34 |
| −5 | 1.43 | 4.18 | 6.36 | 4.18 |
| 0 | 1.93 | 5.11 | 7.73 | 5.14 |
| +5 | 2.49 | 6.16 | 9.28 | 6.22 |
| +10 | 3.14 | 7.33 | 11.02 | 7.44 |
| +15 | 3.87 | 8.65 | 12.96 | 8.81 |
| +20 | 4.70 | 10.11 | 15.13 | 10.33 |
| +25 | 5.63 | 11.72 | 17.52 | 12.02 |
| +30 | 6.66 | 13.50 | 20.17 | 13.89 |
| +35 | 7.82 | 15.45 | 23.07 | 15.95 |
| +40 | 9.09 | 17.58 | 26.25 | 18.21 |
| +45 | 10.51 | 19.92 | 29.72 | 20.69 |
| +50 | 12.07 | 22.47 | 33.51 | 23.40 |
| +55 | 13.78 | 25.25 | 37.63 | 26.36 |
| +60 | 15.66 | 28.27 | 42.12 | 29.58 |
Values are rounded engineering-table figures for service diagnostics; commissioning settings should come from the refrigerant producer's datasheet or calculation software for the exact blend batch.
Superheat = measured suction-line temperature − saturation (dew) temperature at the measured suction pressure. Example on R404A: suction pressure 2.65 bar(g) → saturation −15 °C; a pipe temperature of −7 °C gives 8 K superheat, a healthy figure for a TEV-fed evaporator. Subcooling = saturation (bubble) temperature at the measured liquid pressure − measured liquid-line temperature; 4–8 K indicates a correctly charged condenser. Persistent high superheat with low subcooling points to undercharge or a starving expansion valve — see the catalogue's Danfoss TUA/TUAE expansion valves and service manifolds. Refrigerant is supplied in returnable cylinders such as R134a 12 kg.
A zeotropic blend evaporates and condenses over a temperature range instead of at one point; the difference between dew and bubble temperature at constant pressure is the glide. R448A/R449A glide is about 4–6 K in the useful range, which is why charge must leave the cylinder as liquid and why mid-coil temperature measurements mislead; R404A (<0.7 K) and R410A (<0.2 K) behave almost like single substances.