R-744 (CO2) Pressure at 75°F — Saturation P-T Data
How This Was Calculated
Saturation pressure interpolated from ASHRAE tabular data for R744. Operating in transcritical region — high pressure above critical point.
- P_sat
- Saturation pressure: 1153 PSI
- T_input
- Input temperature: 75°F
- T_data
- ASHRAE tabular reference data: R744
Important Considerations
At 75°F, R744 reaches 1153 PSI — well above the 450 PSI threshold. This is an extreme condensing condition. Verify system high-pressure cutout is properly set and functional. Check for blocked condenser airflow, dirty coil, or refrigerant overcharge. Operating at sustained high pressure significantly reduces compressor life and increases risk of safety relief valve opening.
The saturation pressure shown (for R744 at 75°F) is the baseline for measuring superheat and subcooling. Suction superheat = suction line temperature minus evaporator saturation temperature. Subcooling = condensing saturation temperature minus liquid line temperature. Typical targets: 8–12°F superheat at the evaporator (TXV systems), 10–20°F subcooling at the condenser. Deviations indicate improper charge, metering device issues, or non-condensables.
R-744 (CO2) is classified A1 (non-toxic, non-flammable) but operates at extremely high pressures (up to 1,500+ PSI). Specialized high-pressure rated equipment, piping, and safety valves are mandatory. CO2 can displace oxygen in enclosed spaces — ventilation and detection systems required.
R744 has a GWP of 1 — meaning 1 lb released equals 1 lbs of CO2 equivalent warming over 100 years. This is a low-GWP refrigerant and is considered environmentally preferable under current and projected regulations. It aligns with AIM Act long-term goals and is unlikely to face near-term restrictions. Choosing low-GWP equipment protects against future regulatory compliance costs.
Saturation pressure-temperature data for R744 derived from ASHRAE Fundamentals Handbook, Chapter 30 (Thermophysical Properties of Refrigerants), and verified against manufacturer published data (Chemours Opteon, Honeywell Solstice). Values represent saturated conditions at sea level.