Refrigerants evolve with safety and environmental concerns
By Mike Squires
There have been many changes in the world of refrigerants since I started my career in 1997, not long after the phase out of popular refrigerants containing CFCs. R-12, R-22, and R502 were commonly used in mechanical refrigeration systems and R-11 was commonly used in low pressure centrifugal chiller systems. These refrigerants were a mainstay in the industry for many years.
Prior to synthetic refrigerant usage there were other natural refrigerants such as ammonia (R-717), sulfur dioxide (R-764) and carbon dioxide (R-744). These refrigerants were considered dangerous in common applications and were replaced mainly by CFC synthetic refrigerants in applications where safety was a concern. Flammability and/or toxicity were not very desirable characteristics. So, in the late 1920s to the 1930s a phase out of the previously used natural refrigerants came about.
Times were good in the world of synthetic refrigerants such as CFCs (chlorofluorocarbon) and HCFCs (hydrochlorofluorocarbon). There was exponential use of these refrigerants in refrigeration and air conditioning systems. There was also widespread use of these refrigerants in the making of products such as Styrofoam and as propellent in spray aerosol cans until the 1980s when a hole in the ozone layer in the Earth’s atmosphere was discovered. CFCs played a large part in the deteriorating ozone layer, leading to an international treaty signed by all UN nations and several other nations to reduce and phase out the production and use of these ozone depleting chemicals. This treaty, called the Montreal Protocol, was ratified in 1987.
Changes in the refrigeration industry that followed included the expedited phase out of R-12 and R-502, which were both classified as the harsher of chemicals in the plethora of ozone depleting substances. As of 1996 these refrigerants were no longer allowed to be produced in North America and other areas in the world.
The HCFC refrigerant R-22, the world’s most common refrigerant for use in air conditioning equipment, is classified as an ozone depleting substance but its chemical composition as a HCFC is such that it is not considered as harmful to the ozone layer. Its phase out plan was over a longer period of time; in fact its original phase out date was extended. You can still buy new R-22 today for use with repairs on older systems. You could not purchase new equipment in North America with R-22 as of 2010, and earlier with some manufacturers.
Optimally refrigerants in the industry would be nontoxic and nonflammable, in addition to being ozone friendly as a requirement for common use. The usage of another type of synthetic refrigerant known as a HFC became commonplace in the industry. Early on there were HFC (Hydrofluorocarbon) refrigerants such as R-134a/R-404A. The introduction of these HFC refrigerants brought another hurdle. They were not recommended as being compatible with the compressor oils used in refrigeration compressors for many years, the result being a new product to the industry − polyolester oil, commonly known as POE oil. This POE oil created another learning curve for the industry.
With the challenges the requirement for POE oil in compressors introduced there was a demand for so called “drop-in” refrigerants to take the place of the recently phased out CFC refrigerants. Mixtures of HCFC/HFC blended refrigerants such as R-401A − a R-12 substitute, and R-402A − a R-502 substitute, along with many others came to be. The requirements to keep legacy systems operational meant these blended refrigerants gained popularity in the industry. This marked the beginning of the era when three refrigerant types in a commercial refrigeration mechanic’s van no longer cut it. Gone were the days of R-22/R-12/R-502 being all you needed to stock.
New Kid on the Block
The introduction of HFC refrigerant R-410A came with its own set of issues. R-410A requires POE oil in the compressor and also has higher operational pressures when running. Not only was the higher pressure an issue with component and part manufacturers, it called for a new level of understanding for the individuals who had to work with it. Maximum operating pressures were higher but with that came a requirement for components to have a higher safety factor for approvals for use with R-410A. Parts of the system, such as solenoid valves, which previously had a maximum operation pressure of 500 psi, would now require a maximum operation pressure of 800 psi.
In the beginning manufacturers had separate lines of products, one they had been producing for years and years and a new line of products specific to R-410A. What a time to be alive! It did not take long for most A/C techs to get familiar and comfortable with the nuance of higher pressures and different components. By 2010 R-410A was no longer an uncomfortable new kid on the block.
Enter Global Warming
The escalating issue of global warming and climate change prompted governments to control/reduce the amount of greenhouse gas (GHG) emissions. Unfortunately, the ozone saving refrigerants of the 1990s are considered large contributors to GHG in the atmosphere. This awareness of GHG created another rating to observe with these refrigerants, Global Warming Potential or GWP. A GWP rating is a measure of how potent a GHG is in relation to how long it will take to break down in the atmosphere. GWP ratings are based on emissions of CO2, which is a GHG. The GWP rating of CO2 is a measure of 1. For comparison, refrigerant R-404A has a GWP rating of 3,920. Simply speaking a leak of 1 lb. of R-404A would have the same environmental impact as a leak of 3,920 lbs. of CO2. As you can see, these HFCs from the days gone by are now villains in terms of GHG emissions.
HFO/HFC Blends and Natural Option Gain Popularity
With the regulations imposed on GHGs, system owners and system designers are tasked with finding ways to build and buy systems that are more environmentally friendly. Today this is achieved mainly with the use of more modern synthetic refrigerants and use of natural refrigerants. The newer synthetic refrigerants are HFOs (hydrofluoroolefins), which are used on their own or blended with other HFC refrigerants, such as R-32, to create new refrigerant blends. In many countries R-32 is the choice to replace R-410A and it is actively promoted and adopted by many HVAC OEMs.
Blends can be functional in many types of existing refrigeration and air conditioning equipment. Examples of these HFO/HFC blends would be R-448A (GWP=1387) and R-449A (GWP=1397) for refrigeration applications, and R452B (GWP=698) R-454B (GWP=467) for air conditioning applications.
These types of refrigerants are becoming commonplace in refrigerant retrofits in existing equipment. An equipment owner that has a system with a refrigerant charge of 1,000 lbs. or R-404A would drastically reduce their operational carbon footprint if they retrofitted to a refrigerant such as R-448A, assuming they went through the proper steps to have the recovered R-404A refrigerant properly destroyed or disposed of in an environmentally-friendly fashion.
Natural refrigerants have been on the rise for the past number of years. These would include but not be limited to R-744 (CO2/GWP =1), R-290 (Propane/GWP =0) and R600a (Isobutane/GWP =0). Another natural refrigerant, R-717 (Ammonia /GWP =0), which has been widely used for well over 100 years in larger commercial systems, is finding its way into some smaller applications where synthetic refrigerants were previously explicitly used.
There have been advances in the use of natural refrigerants such as R-290 propane and R600a isobutane, which are highly flammable. The refrigerant charge is kept very low and the electrical components are all solid state or sealed to eliminate the possibility to have an open spark within the electrical components, which was never a factor before.
Another natural refrigerant that has been gaining popularity in the past 10 years in North America is R-744 (CO2/GWP =1). This natural refrigerant fell out of the mainstream use with the advent of synthetic refrigerants due to its characteristics. R-744 does come with new challenges but with development and adoption of the refrigerant it has become a widely used refrigerant in medium to large commercial systems in North America. There have been plenty of developments of smaller R-744 throughout the world, which may eventually be commonplace in time.
We are in the thick of a changing world of refrigerant management. The constant change is creating new issues and new opportunities to evolve and learn. The challenges many of us have faced through these transitions are sure to pop up every now and again, but the bright side is that we now have the luxury of help in our pockets if we say, “OK Google” or “Hey Siri.”
Mike Squires Mike Squires, RSE, is manager, service accounts and technical training at Neelands Group Ltd. in Burlington, ON where he works with customers, and in-house staff on all matters relating to refrigeration. He can be reached at [email protected]
After decades of sharing his refrigeration expertise with industry readers, Phil Boudreau has decided to pass his columnist reins to Mike Squires. It has been a pleasure working with Phil, as we are sure it has been a pleasure for our readers to benefit from his expertise. Phil, we at MB wish you all the best and thank you so much!
This article appears in the January/February 2024 issue of Mechanical Business.