Refrigerant pressure-temperature table

Saturation pressure and temperature for R410A, R32, R134a, R407C, R404A, R290, R744, R1234ze(E) and R513A from -40 to +60 °C, with bubble and dew values for blends and a superheat and subcooling helper.

How to use the table

Choose the refrigerant from the nameplate and what you want to find. To check what pressure the circuit should show at a given evaporating or condensing temperature, use the first option. To convert a gauge reading into a saturation temperature, use the second. For superheat and subcooling, enter the pressure and the pipe temperature measured with a clamp probe at the same point. The full saturation table for the selected refrigerant appears below the result, and the row closest to your value is highlighted.

All pressures are gauge pressures in bar, which is what analogue and most digital manifolds show. Absolute pressure is gauge pressure plus 1.013 bar at sea level. The data were calculated with CoolProp, an open-source library of thermophysical properties, at 1 K steps.

Bubble and dew point for blends

Zeotropic blends such as R407C do not evaporate at a single temperature. At a given pressure the liquid starts to boil at the bubble temperature and the last drop evaporates at the dew temperature. The difference is called glide; for R407C it is about 5 to 7 K. Near-azeotropic blends such as R410A, R404A and R513A have a glide below 1 K, so the two values are almost the same.

The rule for service work is simple:

• Superheat is calculated from the dew temperature, because at the evaporator outlet the refrigerant is vapour.
• Subcooling is calculated from the bubble temperature, because at the condenser outlet the refrigerant is liquid.
• For a pure refrigerant like R32, R134a, R290 or R744, both are the same.

Quick reference table

Saturation pressures in bar gauge at 10 K steps. Use the tool above for 5 K steps, 1 K interpolation and the other refrigerants.

Temperature (°C)	R410A dew	R32	R134a	R407C bubble	R407C dew	R404A dew	R290
-40	0.74	0.76	-0.50	0.19	-0.16	0.30	0.10
-30	1.68	1.72	-0.17	0.86	0.37	1.01	0.67
-20	2.98	3.04	0.31	1.79	1.13	1.99	1.43
-10	4.71	4.81	0.99	3.03	2.19	3.29	2.44
0	6.97	7.12	1.92	4.67	3.59	4.99	3.73
10	9.84	10.06	3.13	6.75	5.44	7.14	5.35
20	13.42	13.73	4.70	9.36	7.79	9.83	7.35
30	17.82	18.26	6.69	12.58	10.75	13.13	9.78
40	23.17	23.77	9.15	16.48	14.40	17.14	12.68
50	29.62	30.40	12.17	21.15	18.86	21.95	16.12
60	37.34	38.32	15.80	26.68	24.27	27.70	20.15

Typical values in chillers

In a chiller producing water at 7 °C, the evaporating temperature is usually 2 to 5 K below the leaving water temperature with a clean plate heat exchanger, and somewhat more with a flooded or shell and tube evaporator in poor condition. For R410A that means a suction pressure of roughly 7.3 to 8.5 bar g. An air-cooled condenser usually condenses 10 to 18 K above the outdoor air temperature: at 30 °C outside, the condensing temperature of a healthy R410A unit is around 40 to 48 °C, which is 23 to 28 bar g.

Superheat at the evaporator outlet is usually 4 to 10 K, depending on the valve type and the manufacturer’s setting. Subcooling at the condenser outlet is usually 3 to 8 K. These ranges are a starting point; the commissioning values of the unit, if they were recorded, are a better reference.

Practical advice

• Measure the pipe temperature with a clamp probe on clean, bare copper and insulate the probe from the ambient air.
• Compare the controller reading with a calibrated gauge. Transducers drift, and a 0.5 bar error is already several kelvin at low pressures.
• For CO2 (R744), the critical point is 31 °C. Above it there is no condensation and no saturation temperature, so subcooling has no meaning in transcritical operation.
• A reading that does not match any plausible saturation state may mean non-condensable gases or the wrong refrigerant in the circuit.

If the readings point to a fault, our chiller alarm guide helps to narrow it down, and the chiller repair page explains how we handle the repair.

Frequently asked questions

Why does my gauge show a different pressure than the table?

The table shows saturation pressure, which is only present where liquid and vapour exist together, such as inside the evaporator or condenser. Pressure drop in the lines, a gauge without temperature compensation or a drifting transducer can add a few tenths of a bar. Large differences point to a measurement problem or a fault.

Should I use the bubble or the dew value for R407C?

Use the dew value for superheat at the evaporator outlet and the bubble value for subcooling at the condenser outlet. Using the wrong one gives an error equal to the glide, which for R407C is several kelvin.

Why is there no value for R744 above 31 °C?

That is the critical point of carbon dioxide. Above it the fluid does not condense, so there is no saturation pressure. CO2 systems in warm weather run transcritically and are controlled by the high pressure valve.

How accurate are the values?

The data come from equations of state in CoolProp and are accurate to a few hundredths of a bar for field work. Between the 1 K data points the tool interpolates on the logarithm of pressure, which adds a negligible error.