Natural refrigerants and hydrocarbons, such as propane, are some of the cleanest and environmentally friendly options out there for air conditioning and refrigeration. However, over the past century America has had very little use of natural refrigerants. Instead, we have opted for synthetic refrigerants such as CFCs, HCFCs, HFCs, and now HFOs. While these synthetic refrigerants get the job done and provide us with that cool air we all crave they are not healthy for the environment.
As we move deeper into the twenty-first century natural refrigerants have become more and more of our everyday life. The pressure is on here in America and across the world to begin phasing down these synthetic refrigerants and replace them with more environmentally friendly natural refrigerants such as R-290 propane.
In this article we’re going to take an in-depth look at propane. We’ll look at the facts, the pros and cons, points of note, the past, present, and the future of this natural refrigerants. Let’s dive in and take a look.
|Name - Scientific:||Propane|
|Chemistry:||C3H8 or CH3CH2CH3|
|Status:||Active & Growing|
|Future:||Will Be Used All Over The World|
|Application:||Supermarkets, Gas Stations, Vending/Ice Machines|
|Application (2):||Refrigerated Transport, Industrial Refrigeration, and Much More|
|Replacement For:||CFCs, HCFCs, and now HFCs|
|Ozone Depletion Potential:||0|
|Global Warming Potential:||3.3|
|Global Warming Risk:||Very Low|
|Toxicity Levels:||A (No Toxicity Identified.)|
|Flammability Levels:||Class 3 - Highly Flammable|
|Lubricant Required:||MO, AB, POE|
|Boiling Point:||−42.25 to −42.04 °C; −44.05 to −43.67 °F; 230.90 to 231.11 K|
|Critical Temperature:||96.7 °C or 206.06 °F|
|Critical Pressure:||4,248 kpa|
|Auto ignition Temperature:||470 °C (878 °F; 743 K)|
|Flash Point||−104 °C (−155 °F; 169 K)|
|Molar Mass:||44.097 g·mol−1|
|Density:||2.0098 kg/m3 (at 0 °C, 101.3 kPa)|
|Melting Point:||−187.7 °C; −305.8 °F; 85.5 K|
|Vapor Pressure:||853.16 kPa (at 21.1 °C (70.0 °F))|
|Manufacturers:||Various Including: Honeywell, Chemours, Arkema, Mexichem, Chinese, etc.|
|Manufacturing Facilities:||All Over Including: USA, Mexico, EU, China, and others.|
|EPA Certification Required:||No|
|Require Certification to Purchase?||No|
|Cylinder Sizes:||1 lb, 20 lb, 100 lb, 200 lb, 420 lb.|
|Purchasing:||Buy R-290 in Bulk|
R-290 PT Chart
R-290 Pros and Cons
Just like with any other refrigerant there are always going to be pros and cons. I’ve said it countless times before, but there are no perfect refrigerants out there. Regardless of what you look at you will always have a downside. As an example of this I like to use Ammonia R-717.
Ammonia is deemed as one of the absolute best refrigerants due to it’s energy efficiency. This is why you see ammonia applications in systems that require very large charges such as meat packing plants. These systems demand a lot of energy and by having the most efficient refrigerant out there these companies can save a lot of money. The downside of ammonia based systems is it’s safety rating. Ammonia is rated as slightly flammable and is rated as toxic if exposed in large enough quantities. It is this reason alone that ammonia has seen very limited use in more residential and commercial applications.
Ok, so now that we have that in mind let’s take a look at some of the pros and cons that come with R-290 propane refrigerant.
- The largest attraction when it comes to using R-290 is it’s effect on the climate. Synthetic refrigerants such as CFCs, HCFCs, and HFCs all damage the environment. Some damage through Ozone depletion and others through Global Warming. Either way, they are harmful. Propane has zero Ozone depletion potential and has a Global Warming Potential of just three. In contrast, one of the most popular HFC refrigerants today, R-404A, has a GWP of nearly four-thousand. These facts alone are why the world is pushing for more and more R-290 applications.
- R-290 has excellent thermodynamic performance, it is energy efficient, and it is very reliable.
- Propane is very affordable and has ample supply especially when compared to some of the more expensive refrigerants out there like R-22.
- The biggest drawback with propane, and with many other hydrocarbons, is flammability. Yes, I know most of you could have guessed that already since we’re dealing with propane. The substance can be quite flammable when put under the right conditions. This is why it is rated as an A3 refrigerant from ASHRAE. The A standing for non-toxic and the 3 standing for ‘higher flammability.’
- Because of this higher flammability risk with propane the amount of charges allowed by governments is quite limited. As an example, in the United States propane based systems can not have a charge greater then one-hundred and fifty grams. This was actually recently changed by the EPA. (UL standard 60335-2-24 – Source) Before that the old limit was just fifty-seven grams. This rule change applied to refrigerators and freezers as well as other approved applications we’ll get into further on into this article.
- Again, due to it’s flammability, R-290 is not suitable for use in retrofitting existing fluorocarbon based systems such as R-22, R-410A, or R-404A. These machines were not made to handle flammable refrigerants such as R-290.
R-290 Points of Note
Ok folks so we’ve got the facts and the pros and cons down. Now let’s take a look at some of the more intricate details of R-290.
- Propane belongs to the hydrocarbon refrigerant classification and it, along with Isobutane, are the most popular hydrocarbon refrigerants used today.
- I mentioned this briefly already but the biggest selling point of R-290 is how environmentally friendly it is. Propane has zero Ozone depletion potential and has a Global Warming Potential of only three. That blows out even some of the newer HFO refrigerants.
- R-290 has a variety of applications that it can be used in including commercial refrigeration, vending machines, ice machines, industrial refrigeration, residential and commercial air conditioning, industrial chillers and much more.
- Again, I mentioned this already in our cons section, but propane is highly flammable and is rated as such through the ASHRAE safety guidelines. This means that you need to be extra careful when working with it and observe all of the proper safety procedures.
- Due to the phasing down of HFCs across the world the demand for hydrocarbon refrigerants like propane have gone up exponentially. Along with that demand has come innovation as we are seeing newer and better ways to use R-290 in various systems.
- Due to it’s flammable nature, systems that use propane have their charge amount strictly limited by governments and worldwide agencies.
- In the United States the EPA has approved propane for use in certain applications but only up to one-hundred and fifty grams.
- There are also pending global proposals to increase the standard one-hundred and fifty gram charge upwards to five-hundred grams.
R-290 EPA Approved Applications
As I was writing this article I took the time to go through the EPA’s SNAP Approved Refrigerant listing. Under each category I searched for R-290 and rather it was approved and for what charge it was approved for. (Be aware that these can change at anytime if the EPA decides to issue a new rule.) Let’s take a look:
- Refrigerators & Freezers – The EPA approved isobutane in 2012 and propane in 2015. Then, in 2018 a change was made that allowed the maximum charge to move up from fifty-seven grams up to one-hundred and fifty grams.
- Ice Machines – These were approved for use on December 1st, 2016 and have charges eligible up to one-hundred and fifty grams. (Rule 81 FR 22827 – Source )
- Industrial Process Refrigeration – Approved in March of 1994 and then changed to June of 2010.
- Vending Machines – Acceptable as of April of 2015 with a charge limit of one-hundred and fifty grams.
- Water Coolers – Acceptable as of December 2016 with a charge limit of one-hundred and fifty grams.
- Retail Food Refrigeration/Freezer – Stand alone equipment acceptable as of December 2011. Maximum charge of fifty-seven grams. ( I searched through out EPA’s rules but I did not see a change to one-hundred and fifty grams for this application.)
- Very Low Temperature Refrigeration – Acceptable as of December of 2016 with a charge limit of one-hundred and fifty grams.
- Residential Light & Commercial Air Conditioners – Approved in August of 2015 with a charge limit of one-hundred and fifty grams. Heat pumps are included in this as well.
While they do mention air conditioners as approved please pay close attention to that charge limit. One-hundred and fifty grams equates out to 0.33 pounds. Now, what air conditioner do you know of that only takes 0.33 pounds of refrigerant? MAYBE a five-thousand BTU system, but even then I feel like that might not be enough. So, while we’re approved for air conditioners I think we’re still a long ways off before we even begin seeing R-290 in window or portable systems.
Also, please note that these regulations can change at any time. It is best to check the EPA’s SNAP Substitutes in Refrigeration and Air Conditioning page by clicking here to check for the most updates.
Homeowners, Air Conditioners, & R-290
When R-22’s prices were hitting all time highs in the summer of 2017 there was a big push for R-22 alternatives from shady manufacturers. Now, I’m not saying that all R-22 alternatives are shady. There are in fact quite a few very well designed ones such as Chemours’ MO99 and Bluon’s TDX-20. But, there are also companies out there who marketed R-290 as an R-22 alternative. They called it ‘R-22a.’ In some cases it was straight propane and in others it was a blend of various refrigerants including R-290.
Not only is R-290 illegal in the US for home air conditioners it is also quite dangerous as these R-22 systems are not outfitted to handle flammable refrigerant. This can lead to safety hazards for the homeowner when ‘retrofitting,’ their system to R-290. Along with that if something does go wrong with their air conditioning system down the road and the homeowner does not know how to repair they will end up calling an HVAC technician. If the homeowner does not inform the technician that they switched their system over to R-290, or the homeowner did not update the stickers on the outside of the unit, then disastrous consequence can happen. In a tragic example out of Australia two technicians were killed when working on what they thought was an R-22 system. It had been switched over to R-290, a leak occurred, and the techs were smoking cigarettes in an enclosed room. (Story can be found here.) Recipe for disaster.
A few years back in 2016 a company out of my home state, Kansas, was fined one-hundred thousand dollars for marketing and selling unapproved alternative refrigerants. They had alternatives for R-12, R-22, and R-502 labeled as HC-12a, HC-22a, and HC-502a. You can read more about this story on our website.
While these poorly done retrofits may not be as much of a problem as they were a few years ago it is best to keep your eyes open when servicing older R-22 systems. You never know what could have been done before you either by the homeowner or a previous technician.
The concept of refrigeration and air conditioning using refrigerants dates back over one-hundred and fifty years ago. In the very beginning stages of invention, innovation, and testing the most common refrigerants used occurred naturally within our environment. These were what’s known as natural refrigerants and within these natural refrigerants existed a subset known as hydrocarbons.
Hydrocarbons were among the very first refrigerants ever used. These included propane, isobutane, ethane, and butane. These hydrocarbons along with the natural refrigerants ammonia and carbon dioxide were the building blocks of modern refrigeration and air conditioning technology that we use today.
While these refrigerants were able to cool to the desired temperatures that we wished there were inherent problems with each one of these natural refrigerants. These ranged from the flammability problem found in hydrocarbons to the toxicity in ammonia and to the extreme operating pressures of carbon dioxide. Whatever the natural refrigerant was there was a problem associated to it.
It was in the 1930’s that the DuPont corporation formed a partnership with General Motors. The goal of this partnership was to synthesize a new type of refrigerant that would be efficient, safe, and affordable to the masses. The end result of this partnership brought into the world some of the most famous refrigerants in the world: R-11, R-12, and R-22. These new refrigerants were known under the classifications Chloroflurocarbons (CFCs) and Hydrochloroflurocarbons (HCFCs).
These new refrigerants reigned supreme for nearly sixty years. The thought of hydrocarbons and natural refrigerants was just that, a thought. Nearly everyone had moved to the new and improved CFC and HCFC refrigerants. While there was still some usage of hydrocarbons they were scarce and more often then not replaced by artificial refrigerants.
It was in the 1980’s when it was discovered that when vented or leaked into the atmosphere the chlorine in these refrigerants would damage the Ozone layer. It had gotten so bad that a thinning of the layer was beginning to form in Antarctica. Scientists sounded the alarm to their governments and after some time a world wide treaty was signed to phase down and eventually phase out all CFC and HCFC refrigerants. This treaty was known as the Montreal Protocol.
To take the place of the phasing out CFC and HCFC refrigerants a new synthesized classification was introduced known as Hydroflourocarbons (HFCs). These refrigerants were very similar to their predecessors except that they did not contain chlorine, so they did not affect the Ozone layer. While there was a rise in natural refrigerants and hydrocarbons usage during this time it was still mostly eclipsed by the newer HFC refrigerants.
The reign of HFCs was much shorter lived then previous refrigerants. It was only about fifteen to twenty years before the world decided to start phasing down HFC refrigerants as well. This time instead of the Ozone it was due to the Global Warming Potential (GWP). The higher the GWP the more damage the product does to the environment and it was found that HFCs have extremely high GWPs. A new solution needed to be found.
While HFCs are still majorly used in today’s world there is a large market for alternative refrigerants such as hydrofluoroolefins (HFOs) and now natural refrigerants including hydrocarbons. The attraction of natural refrigerants is that they are just that, natural. They are environmentally neutral which is exactly what the world is looking for today. On top of that, technology has improved leaps and bounds from where it was over a hundred years ago. In today’s world natural refrigerants and hydrocarbons are much safer.
R-290 Present & Future
Over the past few years there has been a big push to use more and more hydrocarbon refrigerants such as propane and isobutane. One of the biggest hurdles though in using these refrigerants is the various charge limits that have been suggested and implemented by different governments and agencies.
In the early summer of 2018 the International Electrotechnical Commission (IEC) released a drafted proposal that outlined increasing the charge limits on hydrocarbon refrigerants, such as R-2190, from one-hundred and fifty grams upwards to five-hundred grams. The current standard known as IEC60335-2-89 is seen as the worldwide guideline for what charges to use in hydrocarbon based systems.
This proposed changes goes hand in hand with the lobbying efforts of Sustainable Refrigeration Council (NASRC). The aim is to increase the charge limits for a variety of hydrocarbon applications to five-hundred grams. This change would allow R-290 and R-600a (Isobutane) to be deployed to larger systems such as supermarkets and eventually air conditioners. While this change has not yet been approved, most people expect it will be sometime in 2019.
IEC addresses the safety concerns of dealing with a larger R-290 charge in the following manners. The first precaution they give is that the system should be completely air tight… but shouldn’t this already be the case when dealing with a refrigerant cycle? The second precaution is that any construction in or around the system cannot cause excessive vibrations. If these vibrations occur damage to the pipes could happen which could cause the propane to leak out causing an ignition risk. The last safety precaution that they mention is that if a leak does occur that there is enough room for air to flow and for the refrigerant to dissipate. According to IEC If these precautions are followed then there should be no safety difference between a one-hundred and fifty gram system and a five-hundred gram system.
Please note that IEC does not represent the United States of Americas. Their suggestions are just that, suggestions. It is up to individual governments and regulatory agencies to determine the exact amount of hydrocarbon charge that they are comfortable with. Here in the United States the EPA has approved R-290 for use in various applications as long as the charge does not exceed one-hundred and fifty grams.
Regardless of charge limits there are innovations being done every year on R-290 systems. Some of the most recent that I have seen are the stand alone R-290 supermarket systems. These units are just that, stand alone. They are NOT cooled by a control room or centralized unit. Instead, the charge is kept in the unit itself and the freezer/refrigerator can be moved as needed. It also eliminates risk to business owners as if there is a problem with their system it does not bring down the whole row of refrigerators but just one small section.
Something I just read about the other day was that the European Union is working on a double ducted air conditioner that would be designed to replace R-410A systems. This system would use, you guessed it, propane. The proposed system would not be split so there would be no need for refrigerant piping going between parts. This alone would reduce the risk of leakage and make installation much easier. The project is still very much in it’s infancy but it is exciting to see the types of innovations that are being done. For more information on this story please click here.
The number of R-290 applications are rising exponentially with each passing year. It doesn’t matter where you are in the world. If you maintenance other equipment besides your standard home/commercial air conditioners then you will run into a propane system. It will only be a matter of time when we begin to see propane home air conditioners as well just as I mentioned above.
Don’t let the flammability risk scare you away though. Remember, at least in America, the charges on these systems are quite small and as long as you take the proper precautions and follow standard safety practices then you will be fine. Even if the whole world goes for the five-hundred gram charge we’re still only looking at just over a pound of propane for a charge.
Other Websites with information on Propane
- Wikipedia – List of Refrigerants
- Wikipedia – Propane
- YouTube.com – R-290 Maintenance Guideline Video
- Hydrocarbons21.com – Propane limit changed by EPA
- EPA.Gov – 2018 Rule on Refrigerators/Freezers Charge Size
- EPA.Gov – SNAP Approved Refrigerants
- ACHRNews.com – IEC Proposed Changes
- Hydrocarbons21.com – IEC Proposed Changes
- EmersonClimate.com – Propane Pros and Cons
- Refrigerants.com – R-290 Properties