An ammonia leak could cause lethal results if not contained properly, making safety training essential for refrigeration mechanics. (Photo courtesy of the Ammonia Safety Training Institute)Countries around the world are phasing down higher global warming potential (GWP) refrigerants in favour of those that offer lower levels of GWP. This presents the refrigeration industry the opportunity to lead the built environment into the net-zero era. “In the past 35 years, we have seen tremendous change in our industry as countries around the world have chosen to move to products and refrigerants that are less damaging to our environment and impact global warming,” said Dennis Kozina, director of sales for Canada at Emerson.
When it comes to products within the marketplace, there are synthetic and natural refrigerants available at the most basic level. Within each of those categories, it gets much more complicated. Synthetic refrigerants are broken down into mainly four types: chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and the newest addition, hydrofluoroolefin (HFOs). Each containing its own generation of refrigerants; HFOs have the lowest GWP amongst the synthetics, followed by HFCs, HCFCs, and CFCs.
Natural refrigerants have been commercially used for a lot longer than synthetics. The most common is ammonia (R717; GWP of zero) followed by carbon dioxide (R744; GWP of one) and hydrocarbons, which features quite a few but the main one would be propane (R290; GWP of three).
“We’re seeing propane in tons of equipment. For example, in grocery stores or smaller bar fridges, there are a lot of them that are carbon dioxide or a hydrocarbon,” explains Trevor Matthews, founder of Refrigerationmentor.com. “You are also seeing them in heat pumps. It’s growing and I believe it’s just going to continue to grow at a rapid pace.” This is just one opportunity that natural refrigerants have in advancing the HVAC industry.
Read the warning label
Carbon dioxide was first patented as a refrigerant in 1850 and even predates ammonia by more than 20 years. It was largely used in marine applications for both refrigeration and air conditioning on ships. This diminished once refrigerants like R12 (CFC) and R22 (HCFC) came onto the scene and then later commercialized in the 1930s. “These refrigerants could operate at lower pressures and were easier to handle, apply, and install,” explains Kozina. “Carbon dioxide has regained popularity over the past 10 to 15 years due to its low GWP of one.”
A concern associated with carbon dioxide is that it operates at a very high pressure. This means that if there was a leak, the system would lose its refrigerant gas in a matter of minutes and with it, all the cooling capacity. In theory, a customer could potentially lose the entire inventory at a supermarket in just one night, explains John Keating, vice president and general manager of stationary refrigerants at Honeywell. There’s more time with an HFO to fix the situation before getting to the stage of losing produce. Still, in the right situation, any refrigerant could pose a danger, says Matthews.
Qualified-only
This takes us onto how important proper training can be for the refrigeration industry. Some refrigerants, like ammonia, are toxic and flammable; they can be corrosive to skin, eyes, and lungs. According to Kozina, “Only qualified and experienced technicians should be used to install, commission and service equipment using R717. Systems that use R717 must also be designed to mitigate the risks associated with it.”
It is best to err on the side of caution with flammable refrigerants, like propane and ammonia. An open flame or spark could potentially cause ignition if a leak leads to a flammable concentration.
Natural refrigerants do pose safety concerns, yet due to their low GWP levels, they are still increasing in popularity. That isn’t to say that one-day natural refrigerants will completely replace synthetic refrigerants. “We are seeing natural refrigerants gain popularity, but because of the caveats mentioned previously, we believe synthetic refrigerants will also continue to play a key role in moving to lower GWP,” explains Kozina. “We have used synthetics for almost 100 years quite safely, and new synthetic refrigerants with lower GWP ratings continue to be developed.”
“When you compare HFOs to naturals, I think certainly both provide lower GWP options compared to the other choices like HFCs,” explains Keating. On Dec. 27, 2020, the U.S. enacted the American Innovation and Manufacturing (AIM) act, which directs the U.S. Environmental Protection Agency (EPA) to address HFCs by providing new authorities to phase down the production and consumption of listed HFCs, manage HFCs and their substitutes, and facilitate the transition to next-generation technologies.
In Canada, the Ozone-depleting Substances and Halocarbon Alternatives Regulations were amended to control HFCs through a phase-down of consumption, according to the Government of Canada.
Back in 1987, Canada signed the international treaty referred to as the Montreal Protocol on Substances that Deplete the Ozone. It was designed to protect the ozone layer and phase out the manufacturing and consumption of ozone-depleting substances. In 2016, the Kigali Amendment was adopted which included an HFC phase-down amendment.
All in this together
When it comes to replacing refrigerants within a system, HFOs have the benefit that they can be simply dropped on for some of the older HFCs. Whereas if the desire was to switch to a natural refrigerant, the entire system would need to be redesigned, reports Keating. “You couldn’t use existing equipment, you’d have to put a whole new system in because natural refrigerants, particularly carbon dioxide, operate at very, very high pressures.” HFOs don’t pose these same risks.
At the end of the day, both natural and synthetic refrigerants will be important in filling the supply gap left open by the phase-down of high GWP refrigerants, explains Keating. “It is not possible to drop in a natural refrigerant into an existing synthetic refrigeration system, therefore an end-user who chooses to go “natural” would need to replace equipment in an existing system.
In Canada, the Refrigerant Management Canada (RMC) program was created to properly dispose of fluorinated refrigerant waste. The program establishes standards and guidelines for every part of the disposal process.