R-407C PT Chart
Saturation pressure for R-407C from -40°F to 140°F, with liquid (bubble) and vapor (dew) columns. Look up a pressure or temperature, switch to metric, and check typical operating pressures.
By BrazeJobs Team · Updated
R-407C Lookup
Liquid (Bubble)
80.7 psig
Vapor (Dew)
63.1 psig
Bubble Point
28.4°F
Dew Point
39.9°F
Chart range: -40°F to 140°F. Enter vacuum as a negative pressure. Check R-407C superheat and subcooling
R-407C PT Chart
| Temp | Liquid (Bubble) | Vapor (Dew) |
|---|---|---|
| -40°F | 3.0 psig | 4.4 inHg vac |
| -35°F | 5.4 psig | 0.6 inHg vac |
| -30°F | 8.0 psig | 1.8 psig |
| -25°F | 10.9 psig | 4.1 psig |
| -20°F | 14.1 psig | 6.6 psig |
| -15°F | 17.6 psig | 9.4 psig |
| -10°F | 21.3 psig | 12.5 psig |
| -5°F | 25.4 psig | 15.9 psig |
| 0°F | 29.9 psig | 19.6 psig |
| 5°F | 34.7 psig | 23.6 psig |
| 10°F | 39.9 psig | 28.0 psig |
| 15°F | 45.6 psig | 32.8 psig |
| 20°F | 51.6 psig | 38.0 psig |
| 25°F | 58.2 psig | 43.6 psig |
| 30°F | 65.2 psig | 49.6 psig |
| 35°F | 72.6 psig | 56.1 psig |
| 40°F | 80.7 psig | 63.1 psig |
| 45°F | 89.2 psig | 70.6 psig |
| 50°F | 98.3 psig | 78.7 psig |
| 55°F | 108.0 psig | 87.3 psig |
| 60°F | 118.0 psig | 96.8 psig |
| 65°F | 129.0 psig | 106.0 psig |
| 70°F | 141.0 psig | 117.0 psig |
| 75°F | 153.0 psig | 128.0 psig |
| 80°F | 166.0 psig | 140.0 psig |
| 85°F | 180.0 psig | 153.0 psig |
| 90°F | 195.0 psig | 166.0 psig |
| 95°F | 210.0 psig | 181.0 psig |
| 100°F | 226.0 psig | 196.0 psig |
| 105°F | 243.0 psig | 211.0 psig |
| 110°F | 261.0 psig | 229.0 psig |
| 115°F | 280.0 psig | 247.0 psig |
| 120°F | 300.0 psig | 266.0 psig |
| 125°F | 321.0 psig | 286.0 psig |
| 130°F | 342.0 psig | 307.0 psig |
| 135°F | 365.0 psig | 329.0 psig |
| 140°F | 389.0 psig | 353.0 psig |
About R-407C
R-407C is an HFC blend designed to run close to R-22 in AC and heat pumps. It was used in new equipment in some markets and is a common retrofit refrigerant for R-22 systems.
It has a large glide, around 10°F. The liquid (bubble) and vapor (dew) pressures differ a lot at the same temperature, so reading the right column is essential: superheat from dew, subcooling from bubble.
- Retrofit of R-22 residential and commercial AC and heat pumps
- Some chillers and packaged units
- Positive-displacement direct-expansion systems (not flooded evaporators)
R-407C Properties
Key facts for identifying R-407C and choosing tools, oil and replacements.
| Property | Value |
|---|---|
| Type | HFC |
| Composition | R-134a 52%, R-125 25%, R-32 23% by weight |
| ASHRAE safety class | A1 |
| GWP (IPCC AR4) | 1,774 |
| Boiling point at 1 atm | -43.6°F |
| Critical temperature | 187°F |
| Oil | POE (polyolester) |
| Trade names | Suva 407C, Genetron 407C, Forane 407C |
| Replaces | R-22 |
| Replaced by | None |
Typical R-407C Operating Pressures
Suction pressure is the vapor (dew) pressure at the evaporator temperature; head pressure is the liquid (bubble) pressure at the condensing temperature. The temperatures are common design points, not charging targets.
| Condition | Evaporator | Suction | Condensing | Head |
|---|---|---|---|---|
| AC cooling, 95°F outdoor | 40°F | 63.1 psig | 115°F | 280.0 psig |
How to Read the R-407C PT Chart
The chart covers -40°F to 140°F. Pressures are gauge pressure (psig), the number your manifold shows; switch to °C and kPa above if you work in metric. At the cold end, R-407C saturates below atmospheric pressure, so those rows read in inches of mercury vacuum (inHg vac), the same as the vacuum scale on a compound gauge.
R-407C is a zeotropic blend, so it boils over a range of temperatures instead of at one point. That range is the glide. The liquid (bubble) column gives the pressure where the first bubble forms; the vapor (dew) column gives the pressure where the last drop of liquid boils off.
At 40°F, the bubble pressure is 80.7 psig and the dew pressure is 63.1 psig. Read the other way, at 63.1 psig the glide is about 11.5°F.
Use the vapor (dew) column for superheat on the suction line and the liquid (bubble) column for subcooling on the liquid line. Mixing them up shifts the answer by the glide.
Superheat and Subcooling Formulas
The PT chart turns a gauge pressure into a saturation temperature. Compare that with a line temperature to get superheat or subcooling.
- Tsuction
- Suction line temperature near the outdoor unit or compressor, °F
- Tliquid
- Liquid line temperature leaving the condenser, °F
- Tdew
- Dew point at suction pressure (vapor column), °F
- Tbubble
- Bubble point at liquid pressure (liquid column), °F
Gauge pressure (psig) is pressure above atmospheric. Below 0 psig, the chart shows vacuum in inches of mercury.
Worked Example: R-407C Superheat and Subcooling
AC cooling, 95°F outdoor: an R-407C system reads 63.1 psig suction with a 50°F suction line, and 280.0 psig on the liquid line with a 105°F liquid line.
- Dew point at 63.1 psig: 40.0°F.
- Superheat: 50°F − 40.0°F = 10.0°F.
- Bubble point at 280.0 psig: 115.0°F.
- Subcooling: 115.0°F − 105°F = 10.0°F.
Is R-407C Being Phased Out?
R-407C is an HFC with a GWP of 1,774, above the limits for most new AC equipment, so it is used mainly to keep R-22 systems running.
A retrofit from R-22 needs the mineral oil replaced with POE, with the residual mineral oil brought below about 5%, and usually a TXV adjustment.
R-407C Field Tips
Practical points for working on R-407C systems, from the sources below.
Sources: Arkema: Forane 407C retrofit information, Arkema: Forane retrofit guidelines, EPA: Choosing the right R-22 retrofit