R-1150
Pure ethylene (C₂H₄). ASHRAE A3 (highly flammable). GWP 4. 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.
Lower toxicity. High burning velocity (> 100 cm/s) or high heat of combustion. Includes hydrocarbons R-290 (propane), R-600a (isobutane), R-1150 (ethylene), R-1270 (propylene). EPA charge limits, HC-rated equipment design, sealed systems, and leak detection are mandatory.
- Flammability
- High (burning velocity > 100 cm/s)
- Toxicity
- Lower
Classification per ANSI/ASHRAE Standard 34-2022. See full reference.
Saturation pressure-temperature curve
Saturation values from CoolProp 7.2.0 Ethylene. Operating pressure on a running system differs — see the operating-pressure references for in-use values.
R-1150 PT chart PDF — 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). Important service temperatures (normal boiling point, freezing point of water, residential AC evap and condenser targets) are tinted and tagged in the table for at-a-glance shop reference.
R-1150 PT Chart — Pressure-Temperature Saturation Table
1° increments · Source: CoolProp 7.2.0 / manufacturer datasheet · hvacptcharts.com
| Temp (°F) | Pressure (PSIG) |
|---|---|
| -40°FIndustrial LT evap | 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 | 336.6 |
| -6°F | 341.6 |
| -5°F | 346.8 |
| -4°F | 352.0 |
| -3°F | 357.3 |
| -2°F | 362.6 |
| -1°F | 368.0 |
| 0°FIndustrial MT evap | 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 | 468.4 |
| 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°FH₂O 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 | 711.5 |
| Temp (°C) | Pressure (kPa) |
|---|---|
| -40°CIndustrial LT evap | 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 | 2,300 |
| -21°C | 2,363 |
| -20°C | 2,427 |
| -19°C | 2,493 |
| -18°CIndustrial MT evap | 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 | 3,725 |
| -2°C | 3,814 |
| -1°C | 3,905 |
| 0°CH₂O freeze | 3,998 |
| 1°C | 4,092 |
| 2°C | 4,188 |
| 3°C | 4,287 |
| 4°C | 4,386 |
| 5°C | 4,488 |
| 6°C | 4,592 |
| 7°C | 4,698 |
| 8°C | 4,807 |
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 (REFPROP-compatible Helmholtz EOS) or manufacturer datasheet, validated against AHRI Standard 700-2019.
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)-103.8°C / -154.8°F
- Critical point48.6°F at 717 PSIG
- Molar mass28.05 g/mol
- Temperature glideNegligible (0.00°F)
- ODP0
- GWP (AR5, 100-yr)4
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. The high stage uses a refrigerant that condenses at temperatures cold enough to act as the heat sink for the ethylene low stage — typically R-23 or R-503 historically, R-744 (CO₂) in modern cascade designs.
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 4 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 currently regulated by AIM Act or EU F-Gas phase-down. Its very low GWP (4) places it below regulatory thresholds. No published phase-down milestones exist for this refrigerant — it is a forward-compatible option for the current low-GWP transition rather than a refrigerant being phased out.
Global warming potential, in context
Industrial refrigeration & cascade systems
Retrofit and replacement paths
Replacements for R-1150
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; ethylene refrigeration has an excellent safety record in regulated industrial applications. Not for amateur or non-specialist service.