R1234ze(E) PT Chart
Updated October 12, 2026
R-1234ze(E)
Pure HFO — the trans (E) isomer of 1,3,3,3-tetrafluoropropene (CHF=CHCF₃). The default form when 'R-1234ze' is referenced without qualifier. ASHRAE A2L, GWP 1 (US EPA basis, 40 CFR 84.64(b) Table 1; IPCC AR5 lists <1). Honeywell Solstice ze. The low-pressure long-term R-134a replacement in centrifugal chillers and commercial heat pumps.
R-1234ze(E) saturation pressure is 22.2 PSIG at 40°F, 49.5 PSIG at 70°F, and 89.9 PSIG at 100°F. These are the gauge readings on a static, fully-saturated system; a running system's high side sits well above them. The full table below runs from −40°F to 150°F in 1°F steps.
Not yet checked against an independent source.
R-1234ze(E) PT chart — printable saturation table
Looking for the R-1234ze(E) PT chart PDF for shop reference? The complete pressure-temperature saturation table is below: every 1° increment from −40°F to 150°F (or to the refrigerant's critical temperature). Use the Print / Save as PDF button in the table header to download a clean, table-only PDF (the rest of the page is hidden from the print output).
R-1234ze(E) PT Chart — Pressure-Temperature Saturation Table
Computed with CoolProp 7.2.0 in 1°F steps · hvacptcharts.com
| Temp (°F) | Pressure (PSIG) |
|---|---|
| −40°F | 19.1 in. Hg vac. |
| −39°F | 18.7 in. Hg vac. |
| −38°F | 18.4 in. Hg vac. |
| −37°F | 18.1 in. Hg vac. |
| −36°F | 17.7 in. Hg vac. |
| −35°F | 17.4 in. Hg vac. |
| −34°F | 17.0 in. Hg vac. |
| −33°F | 16.6 in. Hg vac. |
| −32°F | 16.2 in. Hg vac. |
| −31°F | 15.8 in. Hg vac. |
| −30°F | 15.4 in. Hg vac. |
| −29°F | 15.0 in. Hg vac. |
| −28°F | 14.6 in. Hg vac. |
| −27°F | 14.2 in. Hg vac. |
| −26°F | 13.7 in. Hg vac. |
| −25°F | 13.3 in. Hg vac. |
| −24°F | 12.8 in. Hg vac. |
| −23°F | 12.4 in. Hg vac. |
| −22°F | 11.9 in. Hg vac. |
| −21°F | 11.4 in. Hg vac. |
| −20°F | 10.9 in. Hg vac. |
| −19°F | 10.4 in. Hg vac. |
| −18°F | 9.9 in. Hg vac. |
| −17°F | 9.3 in. Hg vac. |
| −16°F | 8.8 in. Hg vac. |
| −15°F | 8.2 in. Hg vac. |
| −14°F | 7.7 in. Hg vac. |
| −13°F | 7.1 in. Hg vac. |
| −12°F | 6.5 in. Hg vac. |
| −11°F | 5.9 in. Hg vac. |
| −10°F | 5.3 in. Hg vac. |
| −9°F | 4.6 in. Hg vac. |
| −8°F | 4.0 in. Hg vac. |
| −7°F | 3.4 in. Hg vac. |
| −6°F | 2.7 in. Hg vac. |
| −5°F | 2.0 in. Hg vac. |
| −4°F | 1.3 in. Hg vac. |
| −3°F | 0.6 in. Hg vac. |
| −2°F NBP (atmospheric) | 0.1 |
| −1°F | 0.4 |
| 0°F | 0.8 |
| 1°F | 1.2 |
| 2°F | 1.5 |
| 3°F | 1.9 |
| 4°F | 2.3 |
| 5°F | 2.7 |
| 6°F | 3.1 |
| 7°F | 3.5 |
| 8°F | 4.0 |
| 9°F | 4.4 |
| 10°F | 4.8 |
| 11°F | 5.3 |
| 12°F | 5.8 |
| 13°F | 6.2 |
| 14°F | 6.7 |
| 15°F | 7.2 |
| 16°F | 7.7 |
| 17°F | 8.2 |
| 18°F | 8.7 |
| 19°F | 9.2 |
| 20°F | 9.7 |
| 21°F | 10.2 |
| 22°F | 10.8 |
| 23°F | 11.3 |
| 24°F | 11.9 |
| 25°F | 12.5 |
| 26°F | 13.0 |
| 27°F | 13.6 |
| 28°F | 14.2 |
| 29°F | 14.8 |
| 30°F | 15.4 |
| 31°F | 16.1 |
| 32°F H₂O freeze | 16.7 |
| 33°F | 17.4 |
| 34°F | 18.0 |
| 35°F | 18.7 |
| 36°F | 19.4 |
| 37°F | 20.1 |
| 38°F | 20.8 |
| 39°F | 21.5 |
| 40°F | 22.2 |
| 41°F | 22.9 |
| 42°F | 23.7 |
| 43°F | 24.4 |
| 44°F | 25.2 |
| 45°F | 26.0 |
| 46°F | 26.8 |
| 47°F | 27.6 |
| 48°F | 28.4 |
| 49°F | 29.2 |
| 50°F | 30.0 |
| 51°F | 30.9 |
| 52°F | 31.7 |
| 53°F | 32.6 |
| 54°F | 33.5 |
| 55°F | 34.4 |
| 56°F | 35.3 |
| 57°F | 36.2 |
| 58°F | 37.2 |
| 59°F | 38.1 |
| 60°F | 39.1 |
| 61°F | 40.1 |
| 62°F | 41.1 |
| 63°F | 42.1 |
| 64°F | 43.1 |
| 65°F | 44.1 |
| 66°F | 45.2 |
| 67°F | 46.2 |
| 68°F | 47.3 |
| 69°F | 48.4 |
| 70°F | 49.5 |
| 71°F | 50.6 |
| 72°F | 51.7 |
| 73°F | 52.9 |
| 74°F | 54.0 |
| 75°F | 55.2 |
| 76°F | 56.4 |
| 77°F | 57.6 |
| 78°F | 58.8 |
| 79°F | 60.1 |
| 80°F | 61.3 |
| 81°F | 62.6 |
| 82°F | 63.9 |
| 83°F | 65.2 |
| 84°F | 66.5 |
| 85°F | 67.8 |
| 86°F | 69.2 |
| 87°F | 70.6 |
| 88°F | 71.9 |
| 89°F | 73.3 |
| 90°F | 74.8 |
| 91°F | 76.2 |
| 92°F | 77.6 |
| 93°F | 79.1 |
| 94°F | 80.6 |
| 95°F | 82.1 |
| 96°F | 83.6 |
| 97°F | 85.2 |
| 98°F | 86.7 |
| 99°F | 88.3 |
| 100°F | 89.9 |
| 101°F | 91.5 |
| 102°F | 93.1 |
| 103°F | 94.8 |
| 104°F | 96.5 |
| 105°F | 98.2 |
| 106°F | 99.9 |
| 107°F | 101.6 |
| 108°F | 103.3 |
| 109°F | 105.1 |
| 110°F | 106.9 |
| 111°F | 108.7 |
| 112°F | 110.5 |
| 113°F | 112.4 |
| 114°F | 114.2 |
| 115°F | 116.1 |
| 116°F | 118.0 |
| 117°F | 120.0 |
| 118°F | 121.9 |
| 119°F | 123.9 |
| 120°F | 125.9 |
| 121°F | 127.9 |
| 122°F | 129.9 |
| 123°F | 132.0 |
| 124°F | 134.1 |
| 125°F | 136.2 |
| 126°F | 138.3 |
| 127°F | 140.4 |
| 128°F | 142.6 |
| 129°F | 144.8 |
| 130°F | 147.0 |
| 131°F | 149.3 |
| 132°F | 151.5 |
| 133°F | 153.8 |
| 134°F | 156.1 |
| 135°F | 158.4 |
| 136°F | 160.8 |
| 137°F | 163.2 |
| 138°F | 165.6 |
| 139°F | 168.0 |
| 140°F | 170.5 |
| 141°F | 172.9 |
| 142°F | 175.4 |
| 143°F | 178.0 |
| 144°F | 180.5 |
| 145°F | 183.1 |
| 146°F | 185.7 |
| 147°F | 188.3 |
| 148°F | 191.0 |
| 149°F | 193.6 |
| 150°F | 196.3 |
| Temp (°C) | Pressure (kPa) |
|---|---|
| −40°C | −65 |
| −39°C | −63 |
| −38°C | −60 |
| −37°C | −58 |
| −36°C | −56 |
| −35°C | −54 |
| −34°C | −51 |
| −33°C | −49 |
| −32°C | −46 |
| −31°C | −43 |
| −30°C | −40 |
| −29°C | −37 |
| −28°C | −34 |
| −27°C | −31 |
| −26°C | −27 |
| −25°C | −24 |
| −24°C | −20 |
| −23°C | −17 |
| −22°C | −13 |
| −21°C | −9 |
| −20°C | −4 |
| −19°C NBP (atmospheric) | 0 |
| −18°C | 4 |
| −17°C | 9 |
| −16°C | 14 |
| −15°C | 19 |
| −14°C | 24 |
| −13°C | 29 |
| −12°C | 35 |
| −11°C | 40 |
| −10°C | 46 |
| −9°C | 52 |
| −8°C | 58 |
| −7°C | 65 |
| −6°C | 71 |
| −5°C | 78 |
| −4°C | 85 |
| −3°C | 92 |
| −2°C | 100 |
| −1°C | 107 |
| 0°C H₂O freeze | 115 |
| 1°C | 123 |
| 2°C | 132 |
| 3°C | 140 |
| 4°C | 149 |
| 5°C | 158 |
| 6°C | 167 |
| 7°C | 177 |
| 8°C | 187 |
| 9°C | 197 |
| 10°C | 207 |
| 11°C | 218 |
| 12°C | 229 |
| 13°C | 240 |
| 14°C | 251 |
| 15°C | 263 |
| 16°C | 275 |
| 17°C | 287 |
| 18°C | 300 |
| 19°C | 313 |
| 20°C | 326 |
| 21°C | 340 |
| 22°C | 353 |
| 23°C | 368 |
| 24°C | 382 |
| 25°C | 397 |
| 26°C | 412 |
| 27°C | 428 |
| 28°C | 444 |
| 29°C | 460 |
| 30°C | 477 |
| 31°C | 494 |
| 32°C | 511 |
| 33°C | 529 |
| 34°C | 547 |
| 35°C | 566 |
| 36°C | 585 |
| 37°C | 604 |
| 38°C | 624 |
| 39°C | 644 |
| 40°C | 665 |
| 41°C | 686 |
| 42°C | 708 |
| 43°C | 730 |
| 44°C | 752 |
| 45°C | 775 |
| 46°C | 798 |
| 47°C | 822 |
| 48°C | 846 |
| 49°C | 871 |
| 50°C | 896 |
| 51°C | 922 |
| 52°C | 948 |
| 53°C | 974 |
| 54°C | 1,001 |
| 55°C | 1,029 |
| 56°C | 1,057 |
| 57°C | 1,086 |
| 58°C | 1,115 |
| 59°C | 1,145 |
| 60°C | 1,175 |
| 61°C | 1,206 |
| 62°C | 1,237 |
| 63°C | 1,269 |
| 64°C | 1,302 |
| 65°C | 1,335 |
| 66°C | 1,369 |
Full saturation values at 1° increments. Toggle between °F / PSIG and °C / kPa. Use Print / Save as PDF for laminated shop reference, or download the CSV / JSON below for use in other tools. R-1234ze(E) PT chart data: CoolProp 7.2.0 (published Helmholtz equations of state / mixture models — see the source citations above).
Lower toxicity. Flame propagates in air at 60°C, but with a low burning velocity (≤ 10 cm/s) and a heat of combustion < 19,000 kJ/kg. ASHRAE safety group A2L: lower toxicity and lower flammability. R-32, R-454B, R-1234yf, R-1234ze(E), R-452B, R-454C, R-455A, R-516A are A2L.
- Flammability
- Low (burning velocity ≤ 10 cm/s)
- Toxicity
- Lower (OEL ≥ 400 ppm)
Classification per ANSI/ASHRAE Standard 34-2022. See full reference.
Saturation pressure-temperature curve
Saturation values from CoolProp 7.2.0[2]. Operating pressure on a running system differs — see the operating-pressure references for in-use values.
At a glance
Chemistry
Lubricant compatibility
Explicit E-isomer designation. Long-term low-GWP replacement for R-134a in chillers and heat pumps.
Trade names
- Solstice ze — Honeywell
Common applications
- Centrifugal chillers
- Heat pumps (commercial)
- Foam blowing
- Aerosol propellant
Properties
- Boiling point (1 atm)−2.2°F (−19.0°C)
- Critical point228.9°F (109.4°C) at 512 PSIG
- Molar mass114.04 g/mol
- ODP0
- GWP (100-yr)1 US EPA value, 40 CFR 84.64(b) IPCC: AR4 not assessed · AR5 <1 · AR6 1.37
- Atmospheric lifetime0.045 years
- New-equipment status (US)Not an AIM Act regulated substance; 40 CFR 84.54 GWP limits don't apply.
What is R-1234ze(E)?
R-1234ze(E) is the explicit-isomer designation for the trans (E) form of 1,3,3,3-tetrafluoropropene. When "R-1234ze" appears in ASHRAE 34 nomenclature, datasheets, or product literature without the (E) or (Z) qualifier, the E-isomer is the default — it is the commercially produced form and the one used in HVAC equipment. The (Z) isomer (cis configuration) has substantially different physical properties and is treated as a separate refrigerant.
R-1234ze(E)'s low saturation pressure makes it a natural pressure-match for low-pressure centrifugal chiller designs but means R-1234ze(E) chillers need larger compressor displacement (and physical envelope) than R-134a equivalents at the same cooling capacity.
Where R-1234ze(E) is used
- Low-pressure centrifugal chillers (commercial cooling, district cooling, large office buildings)
- Commercial heat pumps in the EU market
- Component of R-450A, R-513A, R-515A, R-515B blends
- Foam blowing agent (polyurethane insulation panels)
- Aerosol propellant in some specialty applications
Regulatory & phase-down status
R-1234ze(E) is below every regulatory phase-down threshold — its GWP of 1 (the US EPA basis, 40 CFR 84.64, used in regulatory math; below 1 by strict IPCC AR5) is far below AIM Act cutoffs. The barriers to wider adoption are A2L flammability classification (requires A2L-rated equipment design, A2L-listed equipment, refrigerant detection where the standard requires it) and the lower volumetric capacity vs R-134a (larger equipment).
For new chiller installations in markets with mature climate regulation (EU, parts of US), R-1234ze(E) is the long-term capacity-equivalent replacement for R-134a. Existing R-134a equipment continues with reclaimed R-134a or transitions through R-450A / R-513A / R-515B (A1, low-but-not-very-low GWP blends with R-1234ze(E) as the major component).
Service notes
POE oil is the standard lubricant; PVE oil is also approved in some applications. Mineral oil is incompatible. Some specific chiller OEMs use PAG — verify per equipment service literature.
A2L safety class requires: A2L-rated equipment design (A2L-listed equipment or appropriate ignition-source isolation), refrigerant detection where ASHRAE 15 requires it, A2L-rated recovery cylinders, and no open flames during refrigerant service. For larger machine-room installations, ventilation requirements per ASHRAE 15 and IEC 60079-10-1 (hazardous area classification) apply.
Operating cycle
Phase-down timeline
R-1234ze(E) is not an AIM Act regulated substance (not one of the 18 HFCs in 42 U.S.C. 7675(c), and not a blend containing one). The 40 CFR 84.54 GWP limits don't apply.
Global warming potential, in context
Medium-pressure centrifugal & screw chillers
Retrofit and replacement paths
R-1234ze(E) replaces
R-1234ze(E) vs R-134a: saturation pressure
| Temp | R-1234ze(E) | R-134a |
|---|---|---|
| 0°F | 0.8 | 6.5 |
| 40°F | 22.2 | 35.0(+58%) |
| 70°F | 49.5 | 71.1(+44%) |
| 100°F | 89.9 | 124.2(+38%) |
Frequently asked
›What's the difference between R-1234ze, R-1234ze(E), and R-1234ze(Z)?
"R-1234ze" without qualifier is the convention shorthand for the E-isomer (the commercially produced form). "R-1234ze(E)" is the explicit designation when isomer specification matters. "R-1234ze(Z)" is the cis isomer, a separate refrigerant with very different properties (normal boiling point +9.7°C vs E's −19°C). For nearly all HVAC reference purposes, "R-1234ze" and "R-1234ze(E)" refer to the same molecule.
›Why is R-1234ze(E) used in chillers but R-1234yf in cars?
Pressure envelope. The lower pressure of R-1234ze(E) is a better match for low-pressure centrifugal chiller compressor designs where evaporator pressures can be sub-atmospheric. R-1234yf's slightly higher pressure better matches mobile AC reciprocating-compressor envelopes and the existing R-134a service-port infrastructure that needed minimal redesign.
›What is the GWP of R-1234ze(E)?
The headline figure is 1 on the US EPA basis (40 CFR 84.64(b) Table 1) used in regulatory math; IPCC AR5 lists it below 1. R-1234ze(E)'s ~16-day atmospheric lifetime means the underlying climate impact is essentially negligible — any reading represents a 99.5%+ reduction vs R-134a's GWP 1,430.
›What lubricant does R-1234ze(E) use?
Polyolester (POE) oil is the standard. Polyvinyl ether (PVE) is also approved by some manufacturers. Some chiller OEMs use Polyalkylene Glycol (PAG). Mineral oil and alkylbenzene are NOT compatible. Always verify per the equipment OEM's service literature.
›Is R-1234ze(E) chemically stable?
Yes for refrigeration service envelopes. R-1234ze(E) is thermally stable up to typical chiller condensing temperatures (≤160°F) and shows good long-term stability in sealed systems with proper POE oil and dry conditions. Above ~200°F continuous operation, decomposition products can form — relevant for high-temperature heat pump applications where R-1336mzz(Z) is the preferred alternative.
›Can I retrofit an R-134a chiller to R-1234ze(E)?
Not a simple swap. The substantially lower saturation pressure means R-134a-sized compressors lose ~25-30% capacity if simply refrigerant-swapped. The A2L safety class adds equipment-level requirements (refrigerant detection where the standard requires it, A2L-listed equipment) that retrofit usually doesn't deliver. The pragmatic path for R-134a chillers facing GWP pressure: (1) continue with reclaimed R-134a until end of life; (2) retrofit to R-513A or R-450A (A1, lower-but-not-very-low GWP) — these have closer pressure envelopes to R-134a; (3) full equipment replacement with new R-1234ze(E)-rated chiller when capital allows.
Sources & citations
- [1]2017 Guideline for Assignment of Refrigerant Container Colors (AHRI Guideline N-2017). AHRI. 2017. https://www.ahrinet.org/system/files/2023-06/AHRI_Guideline_N_2017.pdf (accessed October 2, 2026)
- [2]CoolProp 7.2.0. CoolProp (I. H. Bell, J. Wronski, S. Quoilin, V. Lemort). https://coolprop.org/ (accessed October 2, 2026). Bell, I. H.; Wronski, J.; Quoilin, S.; Lemort, V. Pure and Pseudo-pure Fluid Thermophysical Property Evaluation and the Open-Source Thermophysical Property Library CoolProp. Ind. Eng. Chem. Res. 53, 2498–2508 (2014). https://doi.org/10.1021/ie4033999