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R-134a pressure–temperature table and P–h diagram

1,1,1,2-Tetrafluoroethane — a single-component HFC. Saturation pressure from −70 to 100 °C, every 2 K, and a pressure–enthalpy diagram to read any state from, computed with CoolProp. Also written R134a.

Safety class A1GWP 1,430 (AR4), 1,530 (AR6)ODP 0Sources

Pressure–enthalpy diagram

log P · h
Pressure (kPa abs)
Specific enthalpy (kJ/kg)

Point anywhere on the diagram to read the state there

Pressure
—
Temperature
—
Specific enthalpy
—
Specific entropy
—
Density
—
Specific volume
—
Saturation
—
Superheat or subcooling
—

Values come from a CoolProp 7.2.1dev tabulation of R-134a (107 pressures, each with states across its liquid, two-phase and vapour spans), interpolated between the points of that grid, and must be verified by a qualified professional before they're relied on.

Enthalpy and entropy are on the IIR datum: h = 200 kJ/kg and s = 1 kJ/(kg·K) for saturated liquid at 0 °C.

Where CoolProp gives no state — outside its equation's range of −103.3 to 181.9 °C, for one — the diagram is shaded, the readout says "Not solved here" and nothing is filled in.

Points

CoolProp
R-134a critical and boiling points
ReadingValue
Critical temperatureCoolProp, from its equation of state101.06°C
Critical pressureCoolProp, from its equation of state4,059.3kPa
Normal boiling pointAt 101.325 kPa, solved by CoolProp−26.07°C

Saturation pressure

kPa abs · bar g
R-134a saturation pressure by temperature, in kPa absolute and bar gauge
T (°C)P (kPa abs)P (bar g)
−708.0−0.93
−689.2−0.92
−6610.6−0.91
−6412.2−0.89
−6213.9−0.87
−6015.9−0.85
−5818.1−0.83
−5620.5−0.81
−5423.2−0.78
−5226.2−0.75
−5029.5−0.72
−4833.1−0.68
−4637.0−0.64
−4441.3−0.60
−4246.1−0.55
−4051.2−0.50
−3856.8−0.45
−3662.9−0.38
−3469.5−0.32
−3276.7−0.25
−3084.4−0.17
−2892.7−0.09
−26101.70.00
−24111.30.10
−22121.60.20
−20132.70.31
−18144.60.43
−16157.30.56
−14170.80.69
−12185.20.84
−10200.60.99
−8216.91.16
−6234.31.33
−4252.71.51
−2272.21.71
0292.81.91
2314.62.13
4337.72.36
6362.02.61
8387.62.86
10414.63.13
12443.03.42
14472.93.72
16504.34.03
18537.24.36
20571.74.70
22607.95.07
24645.85.44
26685.45.84
28726.96.26
30770.26.69
32815.47.14
34862.67.61
36911.88.11
38963.28.62
401,016.69.15
421,072.29.71
441,130.110.29
461,190.310.89
481,252.911.52
501,317.912.17
521,385.412.84
541,455.513.54
561,528.214.27
581,603.615.02
601,681.815.80
621,762.816.61
641,846.717.45
661,933.718.32
682,023.719.22
702,116.820.16
722,213.221.12
742,313.022.12
762,416.123.15
782,522.924.22
802,633.225.32
822,747.326.46
842,865.327.64
862,987.428.86
883,113.630.12
903,244.231.43
923,379.432.78
943,519.334.18
963,664.535.63
983,815.237.14
1003,972.438.71

Gauge pressure is absolute pressure less a standard atmosphere, 101.325 kPa; below it, gauge pressure is negative.

Identity

Kelvin’s refrigerant library
Designation
R-134a (also written R134a)
Name
1,1,1,2-Tetrafluoroethane
Formula
CH₂FCF₃
Kind
single-component HFC

Environment and safety

Cited
Safety class
A1Lower toxicity, no flame propagation. The class assigned in ISO 817 or ANSI/ASHRAE 34, as tabled in UNEP RTOC 2018; the Australian Government lists A1 (AS/NZS ISO 817).
GWP, 100-year (AR4)
1,430IPCC AR4 (2007).
GWP, 100-year (AR6)
1,530IPCC AR6 (2021).
ODP
0Not an ozone-depleting substance in the Montreal Protocol's annexes.

Two GWPs, both for a 100-year horizon. AR4 is the assessment that Australia's Ozone Protection and Synthetic Greenhouse Gas Management Act 1989 and the Montreal Protocol count HFCs in, so it is the figure behind Australia's HFC import phase-down (DCCEEW). The Montreal Protocol's Annexes A, C and F list the same AR4 figures for the CFCs, HCFCs and HFCs they control. AR6 is the IPCC's most recent assessment. The GHG Protocol's table of IPCC GWPs (version 2.0, August 2024) recommends using these latest values.

Sources

  • UNEP RTOC 2018: Annex I to Chapter 2, Tables 2.I-1 to 2.I-3: safety classes as assigned in ISO 817:2014 or ANSI/ASHRAE Standard 34-2016.
  • DCCEEW (Australian Government): Hydrofluorocarbon refrigerants – global warming potential values and safety classifications (last updated 13 December 2024): AR4 GWPs as used under the Ozone Protection and Synthetic Greenhouse Gas Management Act 1989, safety classes from AS/NZS ISO 817:2016.
  • IPCC AR4 (2007): Working Group I, Chapter 2, Table 2.14, 100-year GWP (as corrected in the Working Group I errata).
  • IPCC AR6 (2021): Working Group I, Chapter 7 Supplementary Material, Table 7.SM.7, GWP-100.
  • Montreal Protocol: Annex A, Group I (CFCs), and Annex C, Group I (HCFCs): ozone-depleting potentials.
  • GHG Protocol (2024): IPCC Global Warming Potential Values, version 2.0 (7 August 2024): the recommendation to use AR6.

Source

Computed with
CoolProp 7.2.1dev, HEOS backend — open-source software under the MIT licence
Fluid
R134a, CoolProp's pure-fluid model
Equation of state
TillnerRoth-JPCRD-1994 (CoolProp’s reference key)
Cite
Bell, I.H., Wronski, J., Quoilin, S., Lemort, V. (2014). Pure and pseudo-pure fluid thermophysical property evaluation and the open-source thermophysical property library CoolProp. Ind. Eng. Chem. Res. 53(6), 2498-2508.

Related

Blends with R-134a
R-404A, R-407A, R-407C, R-407F, R-448A, R-449A, R-450A, R-513A
In R-number order
Before: R-32 · After: R-170
Every refrigerant
All refrigerant tables

Use R-134a in Kelvin

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Note

Verify before relying on these figures

The property figures are computed with CoolProp from published equations of state. The GWP, ODP and safety class are the named sources’ figures, a blend’s GWP and ODP summed from its composition. They must be verified by a qualified professional before they’re relied on.