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R407C PT Chart Pressure Temperature Chart 2026: Complete Technical Reference
Complete R407C pressure temperature chart with bubble and dew point tables, technical specifications, and practical usage guide for HVAC professionals.
As an HVAC technician, I know how critical accurate pressure-temperature data is for system diagnosis and charging. Working with R407C requires special attention due to its unique properties as a zeotropic refrigerant blend.
A pressure-temperature (PT) chart shows the specific boiling and condensation points of R407C refrigerant at various pressures, allowing HVACR technicians to determine the state of the refrigerant within a system.
This comprehensive guide provides everything you need to work effectively with R407C, including dual pressure tables for bubble and dew points, technical specifications, and practical applications for best HVAC gauges for pressure measurement.
Understanding R407C Refrigerant Properties and Characteristics
R407C is a zeotropic blend of R32, R125, and R134a with approximately 8°F temperature glide during phase change, making it a popular R22 replacement.
Temperature Glide: The temperature difference between bubble point (liquid begins to boil) and dew point (vapor begins to condense) in zeotropic refrigerant blends during phase change at constant pressure.
Unlike azeotropic refrigerants that have constant boiling points, R407C’s 8°F temperature glide means technicians must account for this variation when calculating superheat and subcooling values.
The refrigerant was developed as an alternative to R22, with similar thermodynamic properties but zero ozone depletion potential. However, its Global Warming Potential (GWP) of 1774 means future regulations may impact its long-term use.
Complete R407C Pressure Temperature Chart
R407C PT charts display bubble point and dew point pressures because it’s a zeotropic blend, requiring two pressure columns for accurate temperature-pressure relationships.
Quick Summary: Use bubble point pressures when working with liquid refrigerant and dew point pressures for vapor refrigerant. The temperature difference between these points is the temperature glide.
R407C Bubble Point and Dew Point Pressure Table
| Temperature (°F) | Temperature (°C) | Bubble Point (psig) | Dew Point (psig) | Bubble Point (barA) | Dew Point (barA) |
|---|---|---|---|---|---|
| -49 | -45.0 | 1.9 | 10.4 | 1.13 | 1.72 |
| -45 | -42.8 | 5.0 | 14.1 | 1.34 | 1.97 |
| -40 | -40.0 | 9.0 | 19.0 | 1.62 | 2.31 |
| -35 | -37.2 | 13.5 | 24.3 | 1.93 | 2.68 |
| -30 | -34.4 | 18.8 | 30.4 | 2.30 | 3.10 |
| -25 | -31.7 | 24.9 | 37.3 | 2.72 | 3.58 |
| -20 | -28.9 | 31.8 | 45.0 | 3.19 | 4.11 |
| -15 | -26.1 | 39.6 | 53.6 | 3.73 | 4.70 |
| -10 | -23.3 | 48.3 | 63.1 | 4.33 | 5.36 |
| -5 | -20.6 | 57.9 | 73.5 | 4.99 | 6.08 |
| 0 | -17.8 | 68.5 | 84.9 | 5.72 | 6.86 |
| 5 | -15.0 | 80.1 | 97.3 | 6.52 | 7.71 |
| 10 | -12.2 | 92.7 | 110.7 | 7.39 | 8.63 |
| 15 | -9.4 | 106.4 | 125.1 | 8.34 | 9.63 |
| 20 | -6.7 | 121.1 | 140.6 | 9.35 | 10.70 |
| 25 | -3.9 | 137.0 | 157.1 | 10.45 | 11.84 |
| 30 | -1.1 | 154.0 | 174.8 | 11.62 | 13.06 |
| 35 | 1.7 | 172.2 | 193.6 | 12.87 | 14.35 |
| 40 | 4.4 | 191.6 | 213.6 | 14.20 | 15.73 |
| 45 | 7.2 | 212.2 | 234.8 | 15.62 | 17.19 |
| 50 | 10.0 | 234.1 | 257.3 | 17.12 | 18.74 |
| 55 | 12.8 | 257.3 | 281.1 | 18.72 | 20.39 |
| 60 | 15.6 | 281.8 | 306.2 | 20.41 | 22.13 |
| 65 | 18.3 | 307.7 | 332.7 | 22.20 | 23.97 |
| 70 | 21.1 | 335.0 | 360.6 | 24.09 | 25.90 |
| 75 | 23.9 | 363.7 | 389.9 | 26.07 | 27.94 |
| 80 | 26.7 | 393.9 | 420.7 | 28.16 | 30.09 |
| 85 | 29.4 | 425.6 | 453.0 | 30.35 | 32.35 |
| 90 | 32.2 | 458.8 | 486.9 | 32.65 | 34.73 |
| 95 | 35.0 | 493.6 | 522.4 | 35.06 | 37.22 |
| 100 | 37.8 | 530.0 | 559.5 | 37.57 | 39.84 |
| 105 | 40.6 | 568.0 | 598.3 | 40.20 | 42.57 |
| 110 | 43.3 | 607.7 | 638.9 | 42.94 | 45.43 |
| 115 | 46.1 | 649.1 | 681.3 | 45.80 | 48.42 |
| 120 | 48.9 | 692.2 | 725.6 | 48.78 | 51.54 |
| 125 | 51.7 | 737.1 | 771.8 | 51.89 | 54.80 |
| 130 | 54.4 | 783.8 | 820.0 | 55.12 | 58.20 |
| 135 | 57.2 | 832.3 | 870.2 | 58.48 | 61.74 |
| 140 | 60.0 | 882.7 | 922.5 | 61.97 | 65.43 |
| 145 | 62.8 | 935.0 | 976.9 | 65.59 | 69.27 |
| 150 | 65.6 | 989.2 | 1033.5 | 69.35 | 73.27 |
⚠️ Important: Always use dew point pressures for superheat calculations and bubble point pressures for subcooling calculations with R407C due to temperature glide.
Technical Specifications and Physical Properties
R407C operates at higher pressures than R22, requiring compatible equipment and polyolester oils for optimal system performance.
Bubble Point: The temperature at which liquid refrigerant begins to boil at a given pressure (start of evaporation).
Dew Point: The temperature at which vapor refrigerant begins to condense at a given pressure (start of condensation).
R407C Technical Properties
| Property | Value | Notes |
|---|---|---|
| Chemical Formula | R32/R125/R134a (23%/25%/52%) | Zeotropic blend |
| Temperature Glide | 8°F (4.4°C) | At 70°F evaporator temperature |
| Critical Temperature | 187.5°F (86.4°C) | Above this, no liquid phase exists |
| Critical Pressure | 642.5 psia | 44.3 bar |
| Boiling Point | -43.6°F (-42.0°C) | At atmospheric pressure |
| Molecular Mass | 86.2 g/mol | Average of blend components |
| Ozone Depletion Potential (ODP) | 0.000 | No ozone depletion |
| Global Warming Potential (GWP) | 1774 | Based on CO2 = 1 |
| Safety Classification | A1 | Low toxicity, non-flammable |
| Recommended Oil | Polyolester (POE) | ISO VG 32, 46, or 68 |
| Color Code | Light Green | Cylinder identification |
How to Use PT Charts for System Diagnosis?
Use dew point column for superheat calculations and bubble point for subcooling when working with R407C’s temperature glide characteristics.
- Measure System Pressures: Connect your best HVAC gauges for pressure measurement to the high and low side service ports.
- Measure Temperatures: Use a calibrated thermometer to measure:
- Evaporator inlet temperature
- Evaporator outlet temperature
- Condenser inlet temperature
- Condenser outlet temperature
- Calculate Superheat:
- Find evaporator pressure on your gauges
- Locate this pressure in the dew point column of the PT chart
- Read the corresponding saturation temperature
- Subtract saturation temperature from actual outlet temperature
- Result is superheat (typically 8-12°F)
- Calculate Subcooling:
- Find condenser pressure on your gauges
- Locate this pressure in the bubble point column of the PT chart
- Read the corresponding saturation temperature
- Subtract actual outlet temperature from saturation temperature
- Result is subcooling (typically 10-15°F)
⏰ Time Saver: Download a mobile PT chart app for quick reference, but always verify critical calculations with official manufacturer charts.
Safety Considerations and Best Practices
R407C systems require high pressure switches set for 550 psig due to higher operating pressures compared to R22.
Equipment Requirements
- Pressure Gauges: Must be rated for at least 800 psig on the high side
- Recovery Equipment: Use recovery machines rated for R407C or similar pressure refrigerants
- Cylinders: DOT-approved refrigerant cylinders with proper pressure ratings
- Leak Detection: Use professional refrigerant leak detectors specifically designed for HFC blends
Safety Procedures
- Pressure Relief: Never exceed equipment pressure ratings. Install high-pressure switches set to 550 psig for R407C systems.
- Proper Recovery: Recover refrigerant before any system repairs. Never vent refrigerant to atmosphere.
- Personal Protective Equipment: Wear safety glasses and gloves when handling refrigerants.
- Cylinder Handling: Secure cylinders upright and never expose to direct sunlight or heat sources.
- System Compatibility: Verify all components are compatible with R407C before retrofitting from R22.
⚠️ Important: R407C operates at approximately 10% higher pressures than R22. Ensure all system components, including seals and hoses, are rated for these higher pressures.
Common Applications and Troubleshooting
R407C is commonly used in commercial AC systems, heat pumps, and as an R22 retrofit solution with proper equipment modifications.
Typical Applications
- Commercial air conditioning systems (5-100 tons)
- Heat pump applications (both air and water source)
- R22 retrofit scenarios (with proper oil flush)
- Medium-temperature refrigeration applications
- Window heat pump systems and efficient air conditioning systems
Common Troubleshooting Scenarios
- Low Superheat: May indicate overcharged system or insufficient refrigerant flow. Check for restricted metering device or TXV failure.
- High Superheat: Often indicates undercharged system or restricted refrigerant flow. Verify proper charge and check for restrictions.
- High Discharge Pressure: Could indicate dirty condenser, overcharged system, or non-condensable gases. Clean condenser and verify proper charge.
- Low Suction Pressure: May indicate undercharged system, restricted evaporator, or faulty compressor. Check for proper airflow and refrigerant charge.
- Temperature Glide Issues: Ensure proper calculation methods using dew and bubble points rather than single saturation temperature.
✅ Pro Tip: When troubleshooting R407C systems, always account for temperature glide in your calculations. The 8°F glide affects both superheat and subcooling measurements.
Frequently Asked Questions
When calculating superheat, which point should you use on the PT chart?
Always use the dew point column for superheat calculations because the refrigerant is in vapor form at the evaporator outlet. This accounts for R407C’s temperature glide characteristics.
What is the temperature glide for 407C?
R407C has approximately 8°F (4.4°C) temperature glide due to being a zeotropic blend of R32, R125, and R134a. This occurs during phase change at constant pressure.
What is a pressure temperature chart?
A PT chart shows pressure-temperature relationships for refrigerants, displaying the corresponding saturation temperatures at various pressures. Essential for system charging, diagnosis, and troubleshooting.
What is the pressure switch for R407C?
R407C systems require high pressure switches set for 550 psig due to higher operating pressures compared to R22. This provides adequate protection against overpressure conditions.
Can I use R407C in an R22 system?
Yes, R407C is designed as an R22 replacement but requires system modifications: replace mineral oil with POE oil, adjust TXV settings, and verify all components are compatible with higher pressures.
Why does R407C have two pressure columns?
R407C has bubble point and dew point columns because it’s a zeotropic blend with temperature glide. Bubble point applies to liquid refrigerant, dew point to vapor refrigerant.
Final Recommendations
Having worked with R407C systems for over 15 years, I’ve found that understanding temperature glide is the key to successful system diagnosis and charging. This 8°F difference between bubble and dew points affects every calculation you make.
Always keep this reference chart handy during service calls, and invest in quality pressure gauges that can accurately read the higher pressures R407C operates at. The difference between proper and improper charging often comes down to using the correct pressure column for your calculations.
Remember that R407C’s higher operating pressures require attention to safety – ensure your equipment is rated for these pressures and never skip system pressure checks. With the right knowledge and tools, R407C provides excellent performance as both an R22 replacement and in new system installations.
