R-290 PT Chart
Saturation pressure for R-290 from -130°F to 160°F. Look up a pressure or temperature, switch to metric, and check typical operating pressures.
By BrazeJobs Team · Updated
R-290 Lookup
Saturation Pressure
64.0 psig
Saturation Temp
40.0°F
Chart range: -130°F to 160°F. Enter vacuum as a negative pressure. Check R-290 superheat and subcooling
R-290 PT Chart
| Temp | Pressure |
|---|---|
| -130°F | 28.1 inHg vac |
| -120°F | 27.1 inHg vac |
| -110°F | 25.9 inHg vac |
| -100°F | 24.0 inHg vac |
| -90°F | 21.8 inHg vac |
| -80°F | 18.7 inHg vac |
| -70°F | 14.9 inHg vac |
| -60°F | 10.2 inHg vac |
| -50°F | 4.3 inHg vac |
| -40°F | 1.4 psig |
| -30°F | 5.7 psig |
| -20°F | 10.7 psig |
| -10°F | 16.7 psig |
| 0°F | 23.7 psig |
| 10°F | 31.8 psig |
| 20°F | 41.1 psig |
| 30°F | 51.8 psig |
| 40°F | 64.0 psig |
| 50°F | 77.7 psig |
| 60°F | 93.0 psig |
| 70°F | 110.2 psig |
| 80°F | 129.4 psig |
| 90°F | 150.5 psig |
| 100°F | 173.9 psig |
| 110°F | 199.6 psig |
| 120°F | 227.8 psig |
| 130°F | 258.7 psig |
| 140°F | 292.3 psig |
| 150°F | 329.0 psig |
| 160°F | 368.8 psig |
About R-290
R-290 is refrigerant-grade propane, a natural refrigerant with a GWP of 3 and no ozone impact. It is efficient and runs at pressures similar to R-22.
It is classed A3, highly flammable, so it is used only in equipment designed for it, with small, tightly limited charges. As a single component, it has no glide. Hudson publishes R-290 data in 10°F steps over a wide range.
Many self-contained R-290 units have no permanent service ports, and their small charges mean a minor leak changes performance quickly. Gauges go on only when a repair calls for it, using the access fittings and procedures the equipment maker specifies, and the chart is then used the same way as for any single-component refrigerant.
- Self-contained commercial reach-ins, display cases and freezers
- Ice machines, beverage coolers and vending machines
- Small heat pumps and window units, mostly outside the US so far
R-290 Properties
Key facts for identifying R-290 and choosing tools, oil and replacements.
| Property | Value |
|---|---|
| Type | Hydrocarbon |
| Composition | Propane, 99.5% or higher purity |
| ASHRAE safety class | A3 |
| GWP (IPCC AR4) | 3 |
| Boiling point at 1 atm | -43.8°F |
| Critical temperature | 205.8°F |
| Oil | As specified by the compressor maker (mineral or POE) |
| Trade names | Propane (refrigerant grade) |
| Replaces | R-404A, R-134a |
| Replaced by | None |
Typical R-290 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 |
|---|---|---|---|---|
| Walk-in cooler (medium temp) | 20°F | 41.1 psig | 110°F | 199.6 psig |
| Walk-in freezer (low temp) | -20°F | 10.7 psig | 110°F | 199.6 psig |
How to Read the R-290 PT Chart
The chart covers -130°F to 160°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-290 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.
The chart has one pressure column because liquid and vapor share the same saturation pressure at each temperature. Use the same column for superheat (suction side) and subcooling (liquid side).
To read it, find the pressure on your gauge and read across to the saturation temperature, or start from a temperature and read the pressure. The lookup above interpolates between rows for you.
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
- Tsat
- Saturation temperature at the gauge pressure, °F
Gauge pressure (psig) is pressure above atmospheric. Below 0 psig, the chart shows vacuum in inches of mercury.
Worked Example: R-290 Superheat and Subcooling
Walk-in cooler (medium temp): an R-290 system reads 41.1 psig suction with a 30°F suction line, and 199.6 psig on the liquid line with a 100°F liquid line.
- Saturation temperature at 41.1 psig: 20.0°F.
- Superheat: 30°F − 20.0°F = 10.0°F.
- Saturation temperature at 199.6 psig: 110.0°F.
- Subcooling: 110.0°F − 100°F = 10.0°F.
Is R-290 Being Phased Out?
R-290 is not being phased down; it is one of the low-GWP refrigerants replacing R-404A and R-134a in self-contained commercial refrigeration.
Charge limits are set by safety standards. UL 60335-2-89 raised the limit for self-contained commercial cases from 150 g to as much as 500 g, subject to code adoption and EPA SNAP listing.
R-290 Field Tips
Practical points for working on R-290 systems, from the sources below.
Sources: ACHR News: UL approves increased R-290 charge limits, ASHRAE: Refrigerant designations and safety classes