Flammable Refrigerants

Last month I wrote on the International Electrotechnical Commission (IEC) and their decision on rather or not to increase the allowed charge limit on hydrocarbon refrigerant applications. Before their decision was made the maximum approved amount was one-hundred and fifty grams under the IEC 60335-2-8 global standard. This proposed increase would have moved the one-hundred and fifty grams limit up to five-hundred grams.

In April the IEC voted against the charge increase amendment. The decision was lost by one no vote. This ruling caused great disappointment across the industry. Many companies and organizations have been pushing to increase charge limits on flammable hydrocarbon refrigerants. The increased charge limit would allow hydrocarbons to be used in larger variety of applications.

Hydrocarbons are one of the top contenders for future refrigerants as the world begins to phase down HFC refrigerants such as R-134a, R-404A, and R-410A due to their high Global Warming Potential. While hydrocarbons can be dangerous due to their flammability they are also one of the most environmentally friendly refrigerants out there as they have no Ozone Depletion Potential and have very little Global Warming Potential.

There is a fine line that has to be walked though as if the charge limit on a propane or isobutane system is too high then the risk of catastrophic failure becomes higher.

This Week’s Recount

It was announced this week by the IEC that a recount was done on last month’s vote. It was found that Malaysia’s no vote was cast illegitimately. The Malaysian vote did not follow the proper voting procedures. In order to vote no you had to provide technical justification for your no vote. If no justification was provided then your vote would be rejected. This is precisely what happened to Malaysia’s vote this month.

While it has not been made one-hundred percent official yet it appears that there are no further roadblocks in the path of IEC adjusting their 60335-2-89 standard. A3 refrigerants will see their charge limit increase to five-hundred grams and A2L refrigerants will see their charge limits increase to one point two kilograms. (One point one pounds on A3 refrigerants and two point four pounds on A2L refrigerants.)


While the IEC is not a governmental organization it serves as a global standard within various industries sand it is who governments look towards for guidance. The IEC ruling to increase charge limits on hydrocarbon applications will be seen as the first steps in seeing further hydrocarbon rollouts across the world.

There is a lot of debate on this decision.  Many folks have expressed concern about increasing charge limits on these highly flammable refrigerants. Obviously, the higher the charge limits the higher the chance of ignition and explosion.  But, if proper precautions are taken by both the manufacturers and the service technicians then all should be fine. All it could take though is one mistake and an incident could occur.

As we move forward from the IEC’s decision we can expect to see other countries and manufacturers beginning to adopt larger hydrocarbon applications. We may first begin to see this in Asia and then in the European Union.

The United States is quite a bit behind the times when it comes to hydrocarbons. It was just a bit ago when the Environmental Protection Agency increased the approved charge limit from fifty grams to one-hundred and fifty grams. So, we just caught up to the global standard and now it has changed again to five-hundred grams.  I predict it will be quite a while before the EPA approves five-hundred gram applications.

No matter how you feel about the IEC’s decision, this topic is another example of the safety versus climate balance. No refrigerants are perfect and while we all know the world wants to get rid of HFCs is it really worth moving away from HFCs if we are risking our own safety to do so? Personally, I think not. I believe we should hold onto HFCs until a more suitable and safer alternative is discovered.

As to what will happen only time will tell.

Thanks for reading,

Alec Johnson



RefrigerantHQ's Pressure Charts

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-600a Pressure Chart

Isobutane is being seen more and more across the world. This holds especially true as various countries begin to phase out the ever common HFC refrigerants such as R-404A and R-134a. There will come a time where HFCs area thing of the past and we need to be ready for it. Today we are seeing isobutane based systems in home refrigerators/freezers, vending machines, ice machines, stand alone supermarket refrigerators/freezers, and many more expanding options. While they are quite popular in Europe and in Asia it is only a matter of time before they start showing up in United States. If you haven’t run into one of these systems yet then it’s only a matter of time. For more information on R-600a please click here to be taken to our R-600a Refrigerant Fact Sheet.

Let’s take a look at our pressure chart:

°F °C psi kpa
-40 -40 4.16 28.7
-36 -38 4.6 31.75
-33 -36 5.08 35.05
-29 -34 5.6 38.62
-26 -32 6.16 42.47
-22 -30 6.76 46.62
-18 -28 7.41 51.09
-15 -26 8.11 55.9
-11 -24 8.85 61.05
-8 -22 9.66 66.57
-4 -20 10.51 72.48
0 -18 11.43 78.79
3 -16 12.4 85.52
7 -14 13.45 92.7
10 -12 14.55 100.33
14 -10 15.73 108.45
18 -8 16.98 117.07
21 -6 18.31 126.21
25 -4 19.71 135.89
28 -2 21.19 146.13
32 0 22.77 156.96
36 2 24.42 168.39
39 4 26.17 180.45
43 6 28.02 193.16
46 8 29.96 206.54
50 10 32 220.61
54 12 34.14 235.41
57 14 36.4 250.94
61 16 38.76 267.24
64 18 41.24 284.32
68 20 43.83 302.22
72 22 46.55 320.95
75 24 49.39 340.54
79 26 52.36 361.02
82 28 55.46 382.4
86 30 58.7 404.72
90 32 62.08 428
93 34 65.6 452.26
97 36 69.26 477.53
100 38 73.08 503.84
104 40 77.05 531.21
108 42 81.17 559.66
111 44 85.46 589.23
115 46 89.92 619.95
118 48 94.54 651.82
122 50 99.34 684.9
126 52 104.31 719.19
129 54 109.47 754.74
133 56 114.81 791.56


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




In the very beginning of refrigerants and air conditioning there were a select few refrigerants used. These refrigerants occurred naturally within our environment and were known as natural refrigerants. These included ammonia, carbon dioxide, water, and oxygen. Among these natural refrigerants under a subset category are what’s known as hydrocarbon refrigerants. Some examples of hydrocarbon refrigerants are propane, butane, ethyl, and isobutane.

In this article we’re going to take an in-depth look at the isobutane refrigerant also known as R-600a. What are the facts on this refrigerant? What are the pros and cons? What are some worthy notations? How is it used today and how will it be used in the future? We will go all over of this and more. Without further adieu let’s dive in and take a look:

The Facts

Name - Scientific:Isobutane
Name (2):HC-600a
Name (3):Care-10
Name (4)R600a
Classification:Hydrocarbon Refrigerant
Chemistry:C4H10 or CH(CH3)2CH3
Status:Active & Growing
Future:Will Be Used All Over The World
Application:Home Refrigerators & Freezers
Application (2):Commercial Refrigerators & Freezers
Application (3):Commercial Vending Machines & Plug-Ins
Application (4):Industrial Refrigeration
Application (5):Medium, High, &Very High Temperature
Replacement For:CFCs, HCFCs, and now HFCs
Ozone Depletion Potential:0
Global Warming Potential: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:−11.7 °C (10.9 °F; 261.4 K)
Critical Temperature:134.7 °C or 274.46 °F
Critical Pressure:3,640 kpa
Auto ignition Temperature:460 °C (860 °F; 733 K)
Flash Point−83 °C (−117 °F; 190 K)
Molar Mass:58.124 g·mol−1
Density:2.51 kg/m3 (at 15 °C, 100 kPa)
Density (2):563 kg/m3 (at 15 °C, boiling liquid)
Melting Point:−159.42 °C (−254.96 °F; 113.73 K)
Vapor Pressure: 3.1 atm (310 kPa) (at 21 °C (294 K; 70 °F))
Manufacturers:Various Including: Honeywell, Chemours, Arkema, Mexichem, Chinese, etc.
Manufacturing Facilities:All Over Including: USA, Mexico, EU, China, and others.
Color:Colorless gas
EPA Certification Required:No
Require Certification to Purchase?No
Cylinder Color:Unknown
Cylinder Sizes:1 lb, 20 lb, 100 lb, 200 lb, 420 lb.

R-600a Pressure Chart

Knowing the pressure and the temperatures associated to the machine you are working on is essential to being able to diagnose any possible issues. Without knowing the temperatures you are more or less walking blind. These pressure checks give you the facts so that you can move onto the next step of your diagnosis. Instead of pasting a large table of information here I will instead direct you to our specific R-600a refrigerant temperature page. This can be found by clicking here.

R-600a Pros & 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-600a Isobutane refrigerant.


  • Just like with other hydrocarbons and natural refrigerants, Isobutane has zero Ozone Depletion Potential, or ODP. When using R-600a there is no risk of damaging the Ozone layer.
  • Sticking with the environmental side of things, R-600a also has a very low Global Warming Potential (GWP) when compared to other synthetic refrigerants such as R-134a or R-404A. Isobutane’s total GWP is 3.
  • There are also no venting regulations to worry about when dealing with R-600a. (Although, I would advocate venting due to the flammability aspect.)
  • Moving to safety, R-600a is rated as an ‘A’ from ASHRAE. The A stands for non-toxic. While that is great news, please note that isobutane is heavier then air and if enough is leaked in a confined area it can displace the oxygen in the room which can cause asphyxiation.
  • R-600a is a very efficient refrigerant with low discharge temperatures. It also operates at a low pressure level when compared to other refrigerants. Not only does this make for an overall quieter machine, but it also reduces chances of failures and extends the life of your compressor.
  • Going along with the efficiency benefit, R-600a actually requires a smaller charge to complete the same job as other refrigerants. As an example, the required charge is forty-five percent less when compared to R-134a and sixty percent less when compared to R-12.
  • Lastly, isobutane is relatively low cost when compared to the synthetic refrigerants we use today.


  • Well, you may have guessed it by now, but the biggest drawback when it comes to R-600a is it’s flammability rating. Yes, just like other hydrocarbons, flammability is the biggest factor. R-600a is rated as a ‘3’ from ASHRAE. That three signifies a ‘higher flammability,’ rating.
  • Because of this higher flammability risk with isobutane the amount of charges allowed by governments is quite limited. As an example, in the United States isobutane 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-600a is not suitable for use in retrofitting existing fluorocarbon based systems such as R-22, R-134a, or R-404A. These machines were not made to handle flammable refrigerants such as R-600a.
  • Depending in the municipalities and governments on where you live you may find that hydrocarbon based systems are not allowed within certain types of buildings. These could be database centers, museums, or government buildings. This is to minimize risk of fire or explosion.
  • Lastly, technicians must be well trained in order to properly use, handle, and maintenance hydrocarbon based systems. While this may not been seen as a con, it does require extra knowledge and cost to train. This limits the amount of people who can work on these types of systems.

R-600a 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.

  • Isobutane belongs to the hydrocarbon refrigerant classification and it, along with propane, are the most popular hydrocarbon refrigerants used today.
  • Isobutane is derived from butane and is created by the isomerization of butane.
  • R-600a is used for blending in a variety of other refrigerants mixes found in HCFC, HFC, and Hydrocarbon classifications. There are nearly twenty different blends with R-600a. (R-441A being one of them.)
  • As I had mentioned earlier in our ‘Pros’ section isobutane has zero Ozone Depletion Potential and a very low Global Warming Potential of three. It is one of the most climate friendly refrigerants out there today. This is one of the main reasons we are seeing a growing hydrocarbon market.
  • Because of the climate friendliness of 600a there are not venting regulations or purchase restrictions that you would normally find on other refrigerants like HFCs and HCFCs. In other words, anyone can purchase and handle R-600a without EPA Clean Air certification.
  • R-600a has an A3 safety rating from ASHRAE. The ‘A’ stands for non-toxic and the ‘3’ stands for higher flammability. This flammability rating is the biggest problem with isobutane and other hydrocarbons.
  • Isobutane is mainly used in household appliances such as refrigerators and freezers. It is also used in medical equipment, vending/ice machines, and in larger scale refrigerators and freezers such as at bakeries or gas stations.
  • R-600a is often the best choice when it comes to medium, high, and very high temperature applications. Whereas R-290 is geared towards lower temperature applications.
  • Ninety-five percent of refrigerators manufactured in Europe, China, Brazil, and Argentina use Isobutane. Even today there are more and more countries adopting R-600a for their refrigerators and freezers.
  • Isobutane is also used in non-refrigerant applications such as aerosol sprays, portable stoves that are used in camps and for geothermal power generation.
  • It is illegal to convert or retrofit existing systems over to using isobutane unless it explicitly stated in the EPA’s SNAP Program. (If outside the US then you will need to check your local regulations.)
  • Isobutane and other hydrocarbons should be handled by trained professionals due to their flammability risk.
  • Due to it’s flammable nature, systems that use isobutane have their charge amount strictly limited by governments and worldwide agencies.
    • In the United States the EPA has approved isobutane 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-600a 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-600a 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:

  • Household Refrigerators & Freezers – Originally approved in December of 2011 and then revised in August of 2018. This change increased the maximum charge to one-hundred and fifty grams (source).
  • Retail Food Refrigeration – Stand Alone Equipment – Acceptable as of April of 2015. Approved applications cannot exceed charges of higher then one-hundred and fifty grams.
  • Vending Machines – Approved as of April of 2015. Approved applications cannot exceed charges of higher then one-hundred and fifty grams (source).

When going through these approved applications I was honestly surprised to see how small this list was. The list is significantly smaller then even it’s rival hydrocarbon R-290. This may be quite different if your outside of the United States.

>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.

R-600A Past

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-600A Present & Future

In the future of refrigeration and air conditioning  we will see these most common refrigerants that we use today, HFCs, become a thing of the past. Already today they are being phased down across the world. The European Union has done away with R-134a and is working towards R-404A and eventually R-410A.

The question though is what refrigerants will replace these? There is a battle going on in the industry between natural refrigerants and the newer artificial refrigerant classification known as hydrofluoroolefins (HFOs). At this point I don’t know if there’s going to be a declared winner or not. It seems that as the years go by we are going to see certain parts of the world, and even certain companies, advocate and use one over the other. If it was me, and my business, I would push for natural refrigerants and hydrocarbons. We never truly know how long the HFOs will be with us. I mean just look at the history of the other artificial refrigerants out there. At least with the natural refrigerants we know they’ll be here forever as there is no risk of phase out.

While the push to use hydrocarbons is admirable there is still a large hurdle that needs to be cleared before we can begin to truly see world wide adoption. This hurdle 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-600a, 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 North American 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-600a and R-290 (Propane) 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-600a charge in the following manners.

  1. 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?
  2. 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 isobutane to leak out causing an ignition risk.
  3. 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-600a for use in some applications as long as the charge does not exceed one-hundred and fifty grams.

United States

Isobutane is quickly becoming the standard refrigerant when it comes to home refrigerators and freezers. In some parts of the world it is becoming standard even in larger commercial refrigerators and freezers that you would find in restaurants or bakeries.

As usual, the United States has lagged behind on this change. We are still using HFCs like R-134a and R-404A to cool our food and drinks. Back in 2015 there were proposed rules by the EPA to begin phasing down HFCs across the US but the rule was overturned by a court’s ruling in 2017. Now, as of today in 2019, there is not yet an Environmental Protection Agency policy on phasing down HFCs. They are expected to make an announcement sometime this year on proposed new HFC rules, but so far there is nothing yet.

Some states have taken matters into their own hands and have begun phasing down HFCs. The problem with this though is that many applications that could use hydrocarbons are still deemed as unacceptable by the EPA’s SNAP program. So, it seems that these states will be forced to go through the HFO or other natural refrigerant routes such as R-717 or R-744.


Regardless of the various regulations, charge limits, and different agencies we can all be assured of one thing. The hydrocarbon market is growing and will continue to grow. There are just too many benefits for them not to grow and only one, albeit significant, drawback to using them.

Just know that these systems are perfectly safe as long as you follow the proper precautions, training, and procedures. Here in the United States we may still be quite a ways off from seeing widespread hydrocarbon usage the time will come where you will run into one of these systems.

Thanks for reading,

Alec Johnson