R1150 PT Chart
Updated October 12, 2026
R-1150
Pure ethylene (C₂H₄). ASHRAE A3 (highly flammable). GWP 3.7. Critical temperature only 9.2°C (48.6°F) — supercritical at any building-HVAC ambient. Used in low-temperature industrial cascade refrigeration where the low boiling point and high vapor pressure at cryogenic temperatures matter.
R-1150 saturation pressure is 274.9 PSIG at −20°F, 401.4 PSIG at 5°F, and 564.9 PSIG at 30°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 48°F in 1°F steps.
Not yet checked against an independent source.
R-1150 PT chart — printable saturation table
Looking for the R-1150 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-1150 PT Chart — Pressure-Temperature Saturation Table
Computed with CoolProp 7.2.0 in 1°F steps · hvacptcharts.com
| Temp (°F) | Pressure (PSIG) |
|---|---|
| −40°F | 195.9 |
| −39°F | 199.4 |
| −38°F | 203.0 |
| −37°F | 206.6 |
| −36°F | 210.3 |
| −35°F | 214.0 |
| −34°F | 217.7 |
| −33°F | 221.5 |
| −32°F | 225.3 |
| −31°F | 229.2 |
| −30°F | 233.1 |
| −29°F | 237.1 |
| −28°F | 241.1 |
| −27°F | 245.2 |
| −26°F | 249.3 |
| −25°F | 253.4 |
| −24°F | 257.6 |
| −23°F | 261.9 |
| −22°F | 266.2 |
| −21°F | 270.5 |
| −20°F | 274.9 |
| −19°F | 279.4 |
| −18°F | 283.8 |
| −17°F | 288.4 |
| −16°F | 293.0 |
| −15°F | 297.6 |
| −14°F | 302.3 |
| −13°F | 307.0 |
| −12°F | 311.8 |
| −11°F | 316.7 |
| −10°F | 321.6 |
| −9°F | 326.5 |
| −8°F | 331.5 |
| −7°F | 336.5 |
| −6°F | 341.7 |
| −5°F | 346.8 |
| −4°F | 352.0 |
| −3°F | 357.3 |
| −2°F | 362.6 |
| −1°F | 368.0 |
| 0°F | 373.4 |
| 1°F | 378.9 |
| 2°F | 384.5 |
| 3°F | 390.1 |
| 4°F | 395.7 |
| 5°F | 401.4 |
| 6°F | 407.2 |
| 7°F | 413.1 |
| 8°F | 419.0 |
| 9°F | 424.9 |
| 10°F | 430.9 |
| 11°F | 437.0 |
| 12°F | 443.2 |
| 13°F | 449.4 |
| 14°F | 455.6 |
| 15°F | 462.0 |
| 16°F | 468.3 |
| 17°F | 474.8 |
| 18°F | 481.3 |
| 19°F | 487.9 |
| 20°F | 494.6 |
| 21°F | 501.3 |
| 22°F | 508.1 |
| 23°F | 514.9 |
| 24°F | 521.9 |
| 25°F | 528.8 |
| 26°F | 535.9 |
| 27°F | 543.0 |
| 28°F | 550.3 |
| 29°F | 557.5 |
| 30°F | 564.9 |
| 31°F | 572.3 |
| 32°F H₂O freeze | 579.8 |
| 33°F | 587.4 |
| 34°F | 595.1 |
| 35°F | 602.8 |
| 36°F | 610.6 |
| 37°F | 618.5 |
| 38°F | 626.5 |
| 39°F | 634.6 |
| 40°F | 642.7 |
| 41°F | 651.0 |
| 42°F | 659.3 |
| 43°F | 667.7 |
| 44°F | 676.3 |
| 45°F | 684.9 |
| 46°F | 693.6 |
| 47°F | 702.5 |
| 48°F | 711.4 |
| Temp (°C) | Pressure (kPa) |
|---|---|
| −40°C | 1,351 |
| −39°C | 1,395 |
| −38°C | 1,440 |
| −37°C | 1,486 |
| −36°C | 1,533 |
| −35°C | 1,580 |
| −34°C | 1,629 |
| −33°C | 1,679 |
| −32°C | 1,730 |
| −31°C | 1,782 |
| −30°C | 1,835 |
| −29°C | 1,889 |
| −28°C | 1,945 |
| −27°C | 2,001 |
| −26°C | 2,058 |
| −25°C | 2,117 |
| −24°C | 2,177 |
| −23°C | 2,237 |
| −22°C | 2,299 |
| −21°C | 2,363 |
| −20°C | 2,427 |
| −19°C | 2,493 |
| −18°C | 2,560 |
| −17°C | 2,628 |
| −16°C | 2,697 |
| −15°C | 2,768 |
| −14°C | 2,840 |
| −13°C | 2,913 |
| −12°C | 2,988 |
| −11°C | 3,064 |
| −10°C | 3,141 |
| −9°C | 3,220 |
| −8°C | 3,301 |
| −7°C | 3,382 |
| −6°C | 3,466 |
| −5°C | 3,550 |
| −4°C | 3,637 |
| −3°C | 3,724 |
| −2°C | 3,814 |
| −1°C | 3,905 |
| 0°C H₂O freeze | 3,998 |
| 1°C | 4,092 |
| 2°C | 4,188 |
| 3°C | 4,286 |
| 4°C | 4,386 |
| 5°C | 4,488 |
| 6°C | 4,592 |
| 7°C | 4,698 |
| 8°C | 4,807 |
| 9°C | 4,918 |
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-1150 PT chart data: CoolProp 7.2.0 (published Helmholtz equations of state / mixture models — see the source citations above).
Lower toxicity, higher flammability. ASHRAE 34 class 3: lower flammability limit ≤ 0.10 kg/m³ or heat of combustion ≥ 19,000 kJ/kg. Includes hydrocarbons R-290 (propane), R-600a (isobutane), R-1150 (ethylene), R-1270 (propylene).
- Flammability
- Higher (LFL ≤ 0.10 kg/m³ or HoC ≥ 19,000 kJ/kg)
- Toxicity
- Lower
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
Used primarily in low-temperature industrial refrigeration cascade systems. Critical point at 9.2°C (48.6°F) — supercritical in most building-HVAC ambient ranges.
Common applications
- Low-temperature cascade refrigeration
- Industrial gas processing
- LNG and ethylene production
Properties
- Boiling point (1 atm)−154.8°F (−103.8°C)
- Critical point48.6°F (9.2°C) at 717 PSIG
- Molar mass28.05 g/mol
- ODP0
- GWP (100-yr)3.7 US EPA value, 40 CFR 84.64(b) IPCC: AR4 not assessed · AR5 not assessed · AR6 not assessed 40 CFR 84.64(b) uses 3.7, the AR4 indirect GWP (Table 2.15).
- New-equipment status (US)Not an AIM Act regulated substance; 40 CFR 84.54 GWP limits don't apply.
What is R-1150?
R-1150 is pure ethylene (C₂H₄) — a two-carbon hydrocarbon with a normal boiling point of −103.7°C / −154.7°F. Among common refrigerants only R-744 (CO₂) has a higher critical pressure, but ethylene's critical temperature is exceptionally low (9.2°C / 48.6°F). Above this temperature no saturation state exists; ethylene is supercritical.
This low critical temperature makes R-1150 unsuitable for most building-HVAC applications (where ambient routinely exceeds 9°C) but ideal for the low-stage of cascade refrigeration systems used in LNG production, ethylene/ethane separation, and ultra-low-temperature industrial applications.
Where R-1150 is used
- Low-stage of cascade refrigeration systems (LNG, ethylene/ethane separation, gas processing)
- Specialty industrial process cooling at −100°F and below
- Some research and laboratory applications at cryogenic temperatures
Regulatory & phase-down status
R-1150 is not phase-down-targeted — GWP 3.7 is below every regulatory threshold. The constraints are entirely the flammability hazard (A3 highly flammable) and the application limitation (low critical temperature restricts use to cryogenic cascade low stages).
Service notes
Mineral oil or polyalphaolefin (PAO) lubricants are standard for ethylene cascade systems. POE is not used. The flammability hazard (A3, similar to propane and isobutane) requires explosion-rated equipment design, ventilation, and trained service personnel. Industrial ethylene refrigeration is a specialty service area; standard HVAC service practices don't directly apply.
Operating cycle
R-1150 is used in: Low-temperature cascade refrigeration, Industrial gas processing, LNG and ethylene production — applications with much lower condensing temperatures than residential AC.
Phase-down timeline
R-1150 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
Industrial refrigeration & cascade systems
Retrofit and replacement paths
Replacements for R-1150
R-1150 vs R-744: saturation pressure
| Temp | R-1150 | R-744 |
|---|---|---|
| 0°F | 373.4 | 291.0(−22%) |
| 40°F | 642.7 | 552.9(−14%) |
Frequently asked
›Why is R-1150's critical temperature so low?
Molecular structure. Ethylene (C₂H₄) is a very small molecule with weak intermolecular forces. The critical temperature is the temperature above which no amount of pressure can produce a distinct liquid phase — this happens when thermal energy exceeds the intermolecular cohesion. Small molecules with weak forces have low critical temperatures. CO₂ (critical 31°C) is similar in this regard; ammonia (132°C) and water (374°C) have higher critical temperatures because of stronger intermolecular bonds.
›Is R-1150 the same as the ethylene used to ripen fruit?
Chemically yes (both are C₂H₄), but refrigerant-grade R-1150 is purified to higher specifications. Industrial ethylene for chemical processes (polymer production, fruit ripening, ethanol manufacturing) is the same molecule with different purity requirements. Don't substitute industrial ethylene for refrigerant-grade — impurities damage refrigeration system components.
›What lubricant does R-1150 use?
Mineral oil or polyalphaolefin (PAO) are standard. The lubricant family matches other hydrocarbon refrigerants. POE is not used.
›Why does the PT chart on this page have no data?
R-1150 is one of 11 manufacturer-blend or specialty refrigerants for which the site's PT chart data is pending. CoolProp 7.2.0 has ethylene as a fluid and the saturation pressures can be computed, but the operational range for refrigeration use is limited to below 9.2°C (the critical temperature). For service work refer to NIST WebBook (chemistry.nist.gov) for ethylene saturation data or the equipment manufacturer's specific operating envelope.
›Is R-1150 dangerous?
Highly flammable (A3) with a wide flammable range in air (3-32% by volume). Industrial ethylene refrigeration is a specialty service area requiring explosion-rated equipment, ventilation, gas-detection sensors, and trained personnel. The risks are well-understood and well-managed in industrial settings. Not for amateur or non-specialist service.
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