source is needed, such as an open flame. Whereas Group A3 refrigerants can be ignited by a smaller ignition source, such as the spark from operation of a standard light switch. Additionally, the velocity of flame propagation must be less than 3.9 inches per second for a refrigerant to be classified as Group A2L. Flame propagation is the speed at which the flame front will move through a cloud of refrigerant gas. This means, that with a flame propagation of less than 3.9 inches per second, ignition of a gas cloud will not result in an explosion—you can literally walk faster than the speed of the flame front. Since these refrigerants will be moving into new residential air-conditioning systems, research was conducted to determine the risks to firefighters. Underwriters Laboratories teamed with the UL Firefighter Safety Research Institute, the Air-Conditioning, Heating, and Refrigeration Institute (AHRI), and fire safety professionals to research and document the actual hazards presented. The fire safety professionals included representatives from California State Fire Marshal’s Office, National Association of State Fire Marshals, International Association of Fire Chiefs, and International Association of Fire Fighters among others. The fire testing and research concluded in early 2021, and the final report “A2L Refrigeration and Firefighter Tactical Considerations” was published in March 2021. The report can be obtained at https://training.ulfirefightersafety.org. A series of fire tests were performed at UL to simulate Group A2L refrigerant release during a fire situation in a dwelling. The question being…Will the Group A2L refrigerants make a significant impact to the fire hazards or the life hazards to the occupants or responding firefighters? Group A2L refrigerants were compared to Group A1 refrigerants which have been utilized in residential air-conditioning systems for many years. What was learned Group A2L refrigerants will produce hydrogen fluoride when the refrigerant is burned. However, it also became evident that even the Group A1 refrigerants produce hydrogen fluoride when burned. The Group A2L tests produced approximately 1-2% more hydrogen fluoride than the Group A1 tests. Hydrogen fluoride is an acid and toxic, however it is readily diluted with water. Normally, there is plenty of water at a fire. As far as the flammability, the results of the testing showed Group A2L to be very similar to Group A1 refrigerants. Table 1 indicates that Group A1 does not ignite at normal temperatures, but may ignite at elevated temperatures. In a dwelling fire, the temperatures are adequate for some Group A1 refrigerants to ignite. However, the flame spread and heat release rate from Group A2L refrigerants is only slightly higher the Group A1 refrigerants. Group A1 refrigerants, which are described as having “no flame propagation at normal temperatures” can ignite at elevated temperatures and can produce hydrogen fluoride when they burn. The UL testing concluded that the hazard of Group A2L refrigerants is very similar to Group A1 refrigerants. What do firefighters need to know Upon arrival at the scene, you will most likely not know if the refrigerant used is flammable or not. Therefore, always assume that the refrigerant is flammable. The temperatures of a fire can damage refrigerant piping and fittings, releasing the contents. A release will most likely not be visible because the refrigerant will vaporize immediately upon release from the system. Most refrigerants produce hazardous substances when burned. Combustible byproducts can be toxic, possibly creating hydrogen fluoride. Both Group A1 and Group A2L refrigerants can result in the formation of hydrogen fluoride. Hydrogen fluoride is toxic, but can be easily diluted with water. Providing pressure ventilation will also move the byproducts outside. Standard personal protective equipment and breathing apparatus will offer protection against these hazardous byproducts. Conclusion The research and testing regarding Group A2L refrigerTHE CALIFORNIA FIRE SERVICE MAGAZINE • MARCH/APRIL 2023 • 19 Continued on page 21
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