One of the very first steps when it comes to diagnosing your home air conditioner, refrigerator, or even your vehicle’s air conditioner is understanding the temperature and the current pressure that your system is operating at. Having these facts along with the saturation point, the subcool, and the superheat numbers for the refrigerant you are working on are essential when it comes to really understanding what is going wrong with your system.
After a visual inspection the very next step for the most seasoned technicians is pulling out their gauges and checking the pressure and temperature. It just becomes second nature after enough calls. I have heard stories of rookie techs calling some of the pros on their team for help on a system that they’re stuck on. It doesn’t matter what the situation is. It doesn’t matter if you’re in Miami or in Fargo. It will never fail that one of the first questions the pros ask the rookie is what is your subcool and what is your superheat? Having and understanding these numbers is key to figuring out what to do next.
But, these numbers won’t do you any good if you don’t know what refrigerant you are dealing with and what the refrigerant’s boiling point is at each pressure level. This article aims at providing you with just that information.
R-290 History
A few decades ago very few people had heard of using propane as a refrigerant. Propane was the stuff you use in your grill and what powered your forklift. While the concept of using R-290 as a refrigerant had been around for over a century it was rarely used due to the flammability risk. Over the years though technology has improved and the need for an environmentally refrigerant has surfaced. The HFC refrigerants that most of the world uses today have a huge impact on Global Warming and an alternative needed to be found. Propane provides the answer to that alternative. Already today in the United States we are seeing propane in vending machines, ice machines, stand alone supermarket refrigerators/freezers, and in many other applications. As time moves forward and the Environmental Protection Agency becomes more comfortable with R-290 we may begin to see more and more applications be authorized to use propane.
If you would like to read more about R-290 propane refrigerant check our refrigerant fact sheet for Propane.
R-290 PT Chart
Let’s take a look at our pressure table for R-290 below.
| °F | °C | PSI | KPA |
| -40 | -40 | 1.4 | 9.7 |
| -35 | -37 | 3.4 | 23.4 |
| -30 | -34 | 5.7 | 39.3 |
| -25 | -32 | 8.1 | 55.8 |
| -20 | -29 | 10.7 | 73.8 |
| -15 | -26 | 13.6 | 93.8 |
| -10 | -23 | 16.7 | 115.1 |
| -5 | -21 | 20.1 | 138.6 |
| 0 | -18 | 23.7 | 163.4 |
| 5 | -15 | 27.6 | 190.3 |
| 10 | -12 | 31.8 | 219.3 |
| 15 | -9 | 36.3 | 250.3 |
| 20 | -7 | 41.1 | 283.4 |
| 25 | -4 | 46.3 | 319.2 |
| 30 | -1 | 51.8 | 357.15 |
| 35 | 2 | 57.7 | 397.8 |
| 40 | 4 | 63.9 | 440.6 |
| 45 | 7 | 70.6 | 486.8 |
| 50 | 10 | 77.6 | 535 |
| 55 | 13 | 85.1 | 586.7 |
| 60 | 16 | 93 | 641.2 |
| 65 | 18 | 101.4 | 699.1 |
| 70 | 21 | 110.2 | 759.8 |
| 75 | 24 | 119.5 | 823.9 |
| 80 | 27 | 129.3 | 891.5 |
| 85 | 29 | 139.7 | 963.2 |
| 90 | 32 | 150.5 | 1037.7 |
| 95 | 35 | 161.9 | 1116.3 |
| 100 | 38 | 173.9 | 1198.9 |
| 105 | 41 | 186.5 | 1285.8 |
| 110 | 43 | 199.6 | 1376.2 |
| 115 | 46 | 213.4 | 1471.3 |
| 120 | 49 | 227.8 | 1570.6 |
| 125 | 52 | 242.9 | 1674.7 |
| 130 | 54 | 258.7 | 1783.7 |
| 135 | 57 | 275.1 | 1896.7 |
| 140 | 60 | 292.3 | 2015.3 |
| 145 | 63 | 310.2 | 2138.7 |
| 150 | 66 | 328.9 | 2267.7 |
| 155 | 68 | 348.4 | 2402.1 |
| 160 | 71 | 368.7 | 2542.1 |
Conclusion
There you have it folks. I hope this article was helpful and if you find that something is inaccurate here in my chart please do not hesitate to reach out to me. I have sourced this the best I could but there is always going to be conflicting data. I’ve seen it multiple times on various refrigerants. I’ll search for a refrigerant’s pressure chart and get various results all showing different pounds per square inch temperatures.
The aim with this article is to give you accurate information so again, if you see anything incorrect please let us know. On top of this post we are also working on a comprehensive refrigerant pressure/temperature listing. The goal is to have every refrigerant out there listed with a pressure/temperature chart that is easily available.