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R-744 Carbon Dioxide Refrigerant Pressure Temperature Chart

Regardless of what system you are working on rather it is a home air conditioner, a vehicle’s air conditioner, a supermarket refrigeration system, or a large scale industrial application they all have one thing in common: Pressure.

Yes, as we all know one of the very first steps when it comes to diagnosing a refrigeration or air conditioning system is determining the various pressures that the system is operating at. Besides a simple visual inspection knowing the operating pressures of the machine is crucial. 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 your subcool is and what is your superheat? Having and understanding these numbers is instrumental 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-744 Carbon Dioxide Pressure Chart

For those of us here in the United States coming across an R-744 Carbon Dioxide application may still be a rare occurrence. But, the world is changing and the popularity of this natural refrigerant is increasing. Along with the popularity the vast array of applications is increasing as well. You can find R-744 being used in vending machines, automobiles, supermarkets, and even in ice-skating rinks. The sheer versatility of R-744 and its climate friendliness is the reason we have seen such growth in its uses.

While we had mentioned earlier the concept of ‘subcool,’ it is important to note that in most cases R-744 applications do not have a subcool. This is because most R-744 systems operate as a transcritical system. Most refrigeration/air conditioning systems operate in what’s known as a subcritical process. This is your standard process that we are all used to. The difference with a R-744 application is that its operating temperatures can exceed the critical point temperature.  Carbon Dioxide’s critical temperature is just under eighty-eight degrees Fahrenheit. That eighty-eight degrees mark can easily be at or below the ambient temperature and when this occurs is when a transcritical system is required.

For more information on transcritical systems you can click here to be taken to our overview. The pressure and temperatures for R-744 can be found below:



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 me know by contacting me here. 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.

Thanks for reading,

Alec Johnson



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