Pressures of R290 refrigerant at -44°F to 120°F temperatures are represented by the R290 PT chart. This pressure temperature chart will tell you what R290 temperature to expect at a certain temperature, and what is the temperature of R290 at a certain pressure. Below you will find an online R290 pressure-temperature chart as well as a printable PDF version of the R290 PT chart you can take with you on a job.
Namely, R290 refrigerant is basically propane. Propane is a useful refrigerant for primarily industrial air conditioning systems but great care must be taken due it propane’s high flammability. Propane for which the R290 PT chart applies has to have at least 98.5% purity and below 100 ppm moisture content.
The R290 pressure temperature chart starts at the boiling point temperature of 44°F (0 psig). At 120°F, the pressure of R290 refrigerant exceeds 200 psig.
If you are working in HVAC, having the R290 PT chart on hand will help in several tasks, including:
- Determining the pressures of R290 on 65-degree, 70-degree, 75-degree, 80-degree, 85-degree, 90-degree, 95-degree, 100-degree days, and so on. We use 3 examples for 60-100 degree days that will illustrate how to use the PT chart to determine the R290 pressures.
- Identify if the line set or a reusable grey bottle containing R290 or another refrigerant.
- Differentiate between R290 and R22. R22 has a very similar boiling point to R290 (-41.4°F to 44°F; that’s only a 2.6°F difference). At 100°F, however, the pressure of R22 is 195.9 psig and the pressure of R290 has a pressure of 174.3 psig (check the R290 PT chart below). This is a 20+ psig difference and you will easily tell if you have an R290 or R22 freon.
- PT chart can also be used to calculate the required R290 superheat and total superheat, and R290 subcooling temperatures.
Note: When using the R290 pressure temperature chart, the HVAC unit must be off and equalized. Equalized means that the pressure on the high side and low side is the same; the whole system is in a saturated liquid and vapor state. If you want to use a PT chart in a running air conditioner, for example, keep in mind that a saturated state is present only at the evaporator and condenser (use the service ports to measure the pressure or temperature).
With that in mind, let’s have a look at the R290 PT chart and 3 examples (you can find the PDF form of this chart at the end):
R290 Pressure Temperature Chart
| Temperature (°F): | Temperature (°C): | R290 Pressure (psig): |
| -44°F | -42.2°C | 0 psig |
| -40°F | -40.0°C | 0.03 psig |
| -36°F | -37.8°C | 0.04 psig |
| -32°F | -35.6°C | 0.04 psig |
| -28°F | -33.3°C | 6.6 psig |
| -24°F | -31.1°C | 8.6 psig |
| -20°F | -28.9°C | 10.7 psig |
| -16°F | -26.7°C | 13.0 psig |
| -12°F | -24.4°C | 15.5 psig |
| -8°F | -22.2°C | 18.1 psig |
| -4°F | -20.0°C | 20.8 psig |
| 0°F | -17.8°C | 23.7 psig |
| 4°F | -15.6°C | 26.9 psig |
| 8°F | -13.3°C | 30.2 psig |
| 12°F | -11.1°C | 33.6 psig |
| 16°F | -8.9°C | 37.7 psig |
| 20°F | -6.7°C | 41.2 psig |
| 24°F | -4.4°C | 45.3 psig |
| 28°F | -2.2°C | 49.7 psig |
| 32°F | 0°C | 54.4 psig |
| 36°F | 2.2°C | 59.0 psig |
| 40°F | 4.4°C | 64.1 psig |
| 44°F | 6.7°C | 69.4 psig |
| 48°F | 8.9°C | 74.9 psig |
| 52°F | 11.1°C | 80.8 psig |
| 56°F | 13.3°C | 86.8 psig |
| 60°F | 15.6°C | 93.2 psig |
| 64°F | 17.8°C | 99.9 psig |
| 68°F | 20.0°C | 106.9 psig |
| 72°F | 22.2°C | 114.1 psig |
| 76°F | 24.4°C | 121.7 psig |
| 80°F | 26.7°C | 129.6 psig |
| 84°F | 29.4°C | 137.9 psig |
| 88°F | 31.7°C | 146.5 psig |
| 92°F | 33.3°C | 173.7 psig |
| 96°F | 35.6°C | 164.7 psig |
| 100°F | 37.8°C | 174.3 psig |
| 120°F | 48.9°C | 228.4 psig |
By matching the temperature and pressure of R290 refrigerant, you can tell what pressure should R290 have at a certain temperature, or what temperature should R290 have at a certain pressure.
To illustrate how to use this chart, we have prepared 3 easy examples of how to read the pressures off the chart (given that the surrounding temperature matches):
Example 1: What Are R290 Pressures On A 60-Degree Day?
From the PT chart, we can read that the pressure of R290 on a 60-degree day is 93.2 psig.
Example 2: What Are R290 Pressures On A 80-Degree Day?
From the PT chart, we can read that the pressure of R290 on an 80-degree day is 129.6 psig.
Example 3: What Are R290 Pressures On A 100-Degree Day?
From the PT chart, we can read that the pressure of R290 on a 100-degree day is 174.3 psig.
R290 Pressure Temperature Chart PDF
As promised, you can get the printable PDF version of the R290 PT chart here if you need it on-site. Here is the full chart you can freely download and take with you:
With this printable chart, we hope that you will be able to use an R290 PT chart without any problems.
You can check PT charts for other common refrigerants such as: