Hydrofluroolefin Refrigerants

Hydrofluroolefin refrigerants, or HFOs, are the latest and greatest to come out to the refrigeration world. HFOs are known as the fourth generation of refrigerants. Their predecessors were the refrigerant classes CFCs, HCFCs, and HFCs. HFOs are widely considered to be the refrigerant of the future.

Each time a new class of refrigerants was introduced it was found out, years later, that the refrigerant in that class damages the environment. The first couple of classes known as CFCs and HCFCs were found to be damaging the Ozone layer due to the Chlorine that they contained. The third generation of refrigerants known as HFCs came around in the 1990’s as an alternative to older classes. But, over time it was found that HFCs had a very high and very damaging Global Warming Potential. (GWP)

The plan now is to phase out HFCs across the world and replace them with either Hydrocarbons or with the new HFO refrigerants designed and created in laboratories owned by Honeywell and Chemours. Much like HFCs HFO refrigerants are comprised of Hydrogen, Fluorine, and Carbon. Chemically, the only difference here between HFCs and HFOs is that HFOs are unsaturated meaning that they have at least one double bond.

The goal of the HFOs are to provide an alternative refrigerant that is safe, non Ozone depleting, and with a relatively low Global Warming Potential number.

HFO Refrigerants

  • R-1234YF or Tetrafluropropene. Also known under the Chemours’ Opteon and Honeywell’s Solstice brand names. 1234YF was the first HFO refrigerant developed by the two companies. It’s intended use was for automotive applications and over the years has begun to see widespread usage across the European Union and here in the United States as well. Chances are if you are purchasing a new vehicle it is coming with HFO-1234YF.
  • R-1234ze or Tetrafluropropene. Also known under the Chemours’ Opteon and Honeywell’s Solstice brand names. R-1234ze is a refrigerant designed to be an alternative to the stationary chillers or commercial air conditioning that you would see in supermarkets or commercial buildings.
  • R-1233zd. Also known under the Chemours’ Opteon and Honeywell’s Solstice brand names. It is designed to be a replacement for R-123. The targeted application here are centrifugal chillers. It has a VERY low GWP of one.
  • R-513A or Opteon XP10. A Chemours Opteon replacement for R-134a on stationary devices.
  • R-449A or Opteon XP40. A Chemours Opteon replacement for R-404A, R-507, and R-22 with a dramatic reduction in GWP and twelve percent improved energy efficiency.
  • R-452A or Opteon XP44. A Chemours Opteon replacement for R-404 and R-507 mainly for systems requiring low discharge temperatures such as refrigerated trucks or rail cars.
  • R-452B or Opteon XL55. A Chemours Opteon replacement for R-410A with a sixty-seven percent GWP reduction, high efficiency, and minimal changes required when retrofitting.
  • R-514A or Opteon XP30. A Chemours Opteon replacement for R-123 with lower GWP, non-flammable, and comes close to performance levels of R-123.
  • R-450A or Solstice N13. A Honeywell Solstice replacement for R-404A. The targeted application here is supermarket chillers or freezers. It’s GWP is sixty-eight percent lower than R-404A and requires fifteen percent less energy to run.
  • R-448A or Solstice N40. A Honeywell Solstice replacement for R-134a. The targeted application here are your heat pumps, air cooled and water cooled chillers, vending machines as well as other small stationary units.

I wanted to make a point to note that I wrote this above section in October of 2017. At the time I wrote this these were all of the HFO refrigerants that I could find. Now, as time moves on there may very well be additional refrigerants added to this list. In fact, I would be very surprised if there weren’t more added just next year. Honeywell and Chemours are working around the clock creating, discovering, and inventing all new HFO refrigerants. I will do my best to keep this list up to date but if you know of some that I missed please do not hesitate to reach out to me by clicking this link.

More Information on HFOs

The History

Ok, so above we covered the very basics of what HFOs are and the types of HFOs that are on the market today. Now we can begin to dig into the actual history of HFOs, what kind of brands there are out today, and what the future looks like for them.

Looking at things from a chemistry perspective HFOs are nothing new. Just like their HFC counterparts HFOs contain Hydrogen, Fluorine, and Carbon. The one real difference between these two refrigerants is that HFOs are unsaturated. In other words they have at least one double bond of carbon. These double bonded molecules are known as Olefins or Alkenes. This is where the name Hydrofluroolefins comes from. While HFOs may have been around for a while there was never a demand for them. HFCs were the favored refrigerant when CFCs and HCFCs went away in the 1990’s. It was in the early 2000’s that things began to change.

In 2006 the European Union came out with a directive known as 2006/40/EC. This directive’s goal was to reduce the emissions of fluorinated greenhouse gases from mobile air conditioning systems. This would be a gradual phase out across the European Union. The end goal was to have automobiles using refrigerants that had a Global Warming Potential, or GWP, number of one-hundred and fifty or less. At the time of this directive most auto manufacturers were using the HFC R-134a. 134a has a GWP number of one-thousand four-hundred and thirty. Due to 134a’s high GWP number the EU’s directive would slowly phase out and ban R-134a. The first major date was 2008, then 2011, and then finally on January 1st 2017 any new vehicle using a refrigerant with a GWP higher then one-hundred and fifty would be banned from the European Union. The problem here was that there wasn’t a viable alternative to HFC refrigerants at the time this directive was made. I’m sure you’ve heard of the expression: Necessity is the mother of invention.

Something had to be done here. Someone had to step up and come up with a solid, stable, and safe refrigerant alternative to the widely used HFC refrigerants. It was the two major refrigerant companies known as Honeywell and DuPont/Chemours that came up to the plate and began researching and producing the first mainstream alternative HFO refrigerant.

A few years later in 2008 Honeywell and DuPont presented the new HFO alternative refrigerant known as 1234YF. This first refrigerant was the first of the new HFO classification line of refrigerants. The presentation was in front of the German Association of the Automotive Industry. (Think Daimler, Volkswagen, and BMW.) The new 1234YF had a GWP number of four. Yes, that’s right four. That is a HUGE improvement when compared to the large number that R-134a came with. 1234Yf was sure to please the European Union.

Not long after the presentation multiple companies and organizations began to endorse the new 1234YF refrigerant. At the time there was an uncertainity in the air of rather the auto manufacturers would go to R-744 (Carbon Dioxide) or to another alternative refrigerant like HFOs. Once the endorsements started coming on for 1234YF the whisperings of CO2 died and nearly everyone jumped on board with the new HFO.

There was one major bump in this road which I will dive into further in our safety section of HFOs but I wanted to mention it here shortly. In 2012 Daimler began their own internal testing with 1234YF on some of their vehicles. They claimed that in some of their tests that when the refrigerant tank ruptured during an accident that the refrigerant ignited and caused an explosion to occur. There were many disputes from numerous companies and organizations from all over the world to this claim. For a time it seemed like German Automakers were going to fight HFOs tooth and nail. They had their hearts set on R-744 CO2.  Over the years there have been numerous court battles and fines issued by the European Union. A lot of these companies have folded into the 1234YF HFO craze but there is one company, Daimler, that is pursuing their own route into the future by developing CO2 R-744 automobile air conditioning systems. In 2017 the final law went into effect across the European Union and 1234YF was found in every new car that was manufactured or imported into the EU. The only exception that I know of is Daimler and their CO2 automobiles.

It seems that with America we always lag behind the environmental standards of the EU. I remember back when I was in the trucking industry a decade ago the government mandated that all new diesel vehicles come with a Diesel Particular Filter and come with Diesel Exhaust Fluid. While this was quite a change here in the States it was old news in Europe. They had been doing this for years. I bring this up because the same thing is happening here with HFCs and HFOs.

The directive in 2006 from the European Union was the catalyst that got the HFO ball rolling. Once that started everyone and every country wanted to jump on board do what they can to phase out HFC refrigerants and replace them with more friendly lower Global Warming refrigerants. These could be Hydrocarbons or CO2 like we discussed before or they could be HFOs.

In the summer of 2015 the Obama Administration’s EPA announced a new rule to their SNAP program. This new rule called RULE 20 was aimed at phasing out HFC refrigerants across the United States. Shortly thereafter in 2016 nations gathered around the world and signed the Kigali Amendment to the Montreal Protocol. This amendment promised to phase out HFC refrigerants across the globe and replace them with more environmentally friendly alternatives such as HFOs.

While the demand for HFOs has already hit the European Union it has still to come in full force to the United States, but everyone knows that it is coming. DuPont/Chemours and Honeywell know this fact all too well. The Chemours Company is building the largest HFO manufacturing plant in the world right here in the United States in Corpus Christi, Texas to be exact. Honeywell is doing something very similar and has built and launched a new HFO plant in Geismar, Louisiana.

Safety Concerns

Let me get this out of the way first and foremost. There is no best refrigerant. Every refrigerant on the market today has Pros and Cons. If we go way back in the day of Ammonia based refrigerant we had the con of toxic chemicals leaking into your home if a leak occurred. HFCs were a relatively stable, safe, and non-flammable refrigerant but as I have covered up above they had the high Global Warming Potential.

The new HFO refrigerants have the big pro that they have a significantly lower Global Warming number but the sacrifice that we have to make for achieving this is the risk of flammability.

Refrigerants have three flammability classifications. The first known as class 1 indicates refrigerants that do not show flame propagation when tested in air at seventy degrees Fahrenheit. Class 2 indicates refrigerants that have a lower flammability limit. Finally, class 3 indicates refrigerants that are highly flammable. An example of a class 3 flammability refrigerant would be R-290 also known as Propane. (Think Hank Hill!)

The HFC refrigerant R-134a has a flammability rating of 1, just like most other HFC refrigerants on the market today. The newer HFO-1234YF has a flammability rating of 2. While it may not seem like a large difference I should point out again that there are only three levels. We’re going up an entire level so that we can reduce Global Warming Potential on our refrigerants. Now, don’t get me wrong here. HFOs just like other refrigerants in the market are safe in the right hands. If you know what you are doing then you’ll be just fine.

There is a risk that comes with replacing R-134a with an HFO. Remember now that 134a and 1234YF applications are mobile, after all they are automobiles. With a mobile application there is a chance of collision and with a chance of collision there is a chance of one of the refrigerant lines rupturing and leaking refrigerant across the rest of the car’s hot engine. No what would happen if that refrigerant that was spewing all over your hot engine was flammable?

This precise scenario is what the German automaker Daimler discovered in 2012. Daimler found that in a severe head on collision the refrigerant line can break apart and spray the 1234YF onto the exhaust system causing a fire. They even recorded a video showing a Mercedes-Benz hatchback catching fire under the hood after 1234YF refrigerant leaked onto the exhaust. The test can be seen in the below video. While the captions in German you don’t need them to understand what is happening here. The moment that refrigerant escapes it ignites nearly instantly. Terrifying stuff.

This test from Daimler shook the industry across the globe. There had been endless tests done on 1234YF before this by Honeywell, Chemours, and many other companies and they all came back safe. After this Daimler test hundreds of additional tests were conducted by other companies and again they all came back as safe.

Now, I can’t tell you who is in the right here. No one really knows. I will say that in 2015 Daimler did come around and state that they would publicly use 1234YF in their newer vehicles. I feel that this is just a cover though while Daimler develops and perfects their CO2 automobile technology. Once it is ready it will be rolled out for all of their makes and models and 1234YF will be left behind.

The question on everyone’s mind is if HFOs are safe. As I said before there have been numerous studies all saying yes. On top of that though I will also state that as I write this there are now thirty-five million 1234YF vehicles on the road today and I have not yet heard of a fire or explosion caused by them. I can guarantee that at least a few of these cars have had head on collisions but there has not been an incident yet. I like those odds.


Alright folks so we’ve gone into what HFOs are, their history, their future, and even the potential safety hazards. Now let’s take a look at the two brand names of HFO refrigerants that are on the market today. As I write this article in October of 2017 there are two main brand names and they both come from the two largest refrigerant manufacturers in the world: DuPont/Chemours and Honeywell.

Honeywell’s new brand name for HFO refrigerants is known as Solstice. DuPont, now split off into Chemours, brand name is known as Opteon. When a new refrigerant is released under these brand names it is released under a different name then what you may be used too. An example of this if we look at R-513A. To the industry it is known as R-513A but to Chemours it is known as Opteon XP10. Yes, I know it’s confusing but I can assure you that they are the same exact thing. Another example is the 1234YF refrigerant. This refrigerant from Honeywell is referred as Solstice YF. If you were to buy this from Chemours it would be known as Opteon YF. It’s the same thing just different labeling.

One additional point that I want to make on the HFO brand names is that at this point in time there are only two. This has me concerned due to the severe lack of competition. If you look at HFC refrigerants it seems like everyone and their brother makes them and that’s not even counting the imported Chinese product. All of this product on the market allows prices to stay relatively low and prevents companies from gouging consumers and contractors. I feel that it is going to be a shock to a lot of shops, dealerships, and even consumers when they need to recharge their HFO automobile and they find out that it’s seventy-two dollars a pound at a wholesale cost. If your car takes two pounds of refrigerant you’re looking at one-hundred and fifty dollars to recharge and that’s before the shop’s markup. Quite the difference when comparing it to a five dollar can of R-134a. That’s not even mentioning all of the new equipment that will have to be bought to service 1234YF vehicles.


It may take another decade, maybe even two, but I can assure you ladies and gentlemen that HFCs are dying. They will be entirely gone before you know it and they will be replaced by the newer and better HFO refrigerants.  Are you ready?

Thanks for reading,

Alec Johnson