Author: Shannon Horn, Commercial Business Director, Perimeter Solutions
Since the inception of aerial firefighting in the 1920s, the tools and techniques used to combat wildfires have evolved significantly. Major advancements in aircraft, equipment, and fire retardant technology have helped firefighters to better address the growing challenges posed by longer, more intense wildfire seasons.
Today, PHOS-CHEKยฎ fire retardant plays a critical role in wildfire suppression. For more than 60 years, it has been a trusted solution for the U.S. Forest Service and fire management organizations worldwide. While its effectiveness is often taken for granted, it took years of research to identify phosphate as the most effective active ingredient. As wildfire seasons have grown to be more unpredictable, ongoing innovations in fire retardant technology continue to enhance both the performance and environmental impact of these vital firefighting tools.
Caption: Phosphate-based PHOS-CHEKยฎ has continually evolved since being introduced in 1963 to help firefighters meet the challenge of longer, more intense wildfire seasons.
Finding the Right Active Ingredient
Research into fire retardant chemicals started more than 80 years ago. One of the earliest studies, conducted at the University of Idaho in 1940, tested the efficacy of various chemicals in reducing the combustibility of sawdust. Among the chemicals evaluated, diammonium phosphate was determined to be the most effective, setting the stage for further development in phosphate-based fire retardants.1
Then in 1954, the U.S. Forest Service (USFS) launched a major study known as Operation Firestop. The study evaluated various fire retardant chemicals to determine their ability to slow ignition times, reduce fire intensity, and suppress flames. The findings reinforced the efficacy of ammonium phosphate as a superior fire retardant, while other chemicals tested were found to be less effective.2
Advancements in Fire Retardant Technology
Following these studies, phosphate-based retardants became the industry standard and since it started being used, the chemical formulations of these retardants have been refined to improve their performance and safety for both the environment and firefighting equipment.
One significant innovation came in the 1970s with the introduction of coloring agents. Iron oxide was used to improve visibility for pilots conducting aerial drops, a critical development that helped to ensure accuracy when creating fire lines from the air. Despite the enhanced visibility iron oxide provided, it had the drawback of leaving long-lasting stains on the ground.3 To overcome that, โfugitiveโ coloring agents were introduced in 1975. These new agents faded over time, making them more suitable to use in aesthetically sensitive areas like national parks.4
Caption: Coloring agents were first added to fire retardant in the early 1970s to improve visibility for pilots conducting aerial drops.
In 1985, further improvements were made to the chemical makeup of fire retardants. A synergistic blend of ammonium sulfate and ammonium phosphates was introduced, offering similar fire suppression performance at a lower cost.5 Then in 1999, the first 100% phosphate liquid concentrate fire retardant was introduced with PHOS-CHEKยฎ LC95A. This retardant had a better environmental profile and enhanced fire management capabilities compared to earlier solutions.
The next innovation came in 2014 with the introduction of ultra-high visible fire retardant. It’s exceedingly vivid when dropped from aircraft and when it’s on the ground. This helps pilots to see where they are dropping the retardant even during highly active wildfires with dark, smoke-filled skies.
Recent advancements in fire retardant technology have focused on improving its environmental profile and extending its durability. Fire retardant can now be applied from the ground months in advance of wildfire season, where it works similarly to aerial applications. When fire approaches, the phosphate in the solution forms a carbon layer that prevents combustion, helping to stop the spread of wildfires until a significant rain event occurs.
Proven Solution for Todayโs Wildfires
Phosphate-based retardants are a key resource in wildfire suppression due to decades of research and field testing. Their consistent performance, environmental considerations, and ongoing innovation make them the go-to choice for fire management agencies around the world. With wildfires becoming more frequent and intense, ensuring firefighters have access to the best tools available is more important than ever.
1McCarthy, Joseph, L., โDecreasing the Combustibility of Sawdustโ, Building, Master Buildersโ Federation of Australia, July 1941, pg. 78. https://nla.gov.au/nla.obj-297527567/view?sectionId=nla.obj-314260699&partId=nla.obj-297577970#page/n77/mode/2up, Accessed 04 October 2024
2Richardson, S.D., โOperation Firestop.โ Empire Forestry Review, vol. 38, no. 1 (95), Commonwealth Forestry Association, 1959, pp. 26โ34, http://www.jstor.org/stable/42600576, Accessed 04 October 2024
3,4, 5โLong-Term Fire Retardants: History, Innovation and Preparing for the Future of Wildfiresโ, Perimeter Solutions, January 2022, https://www.perimeter-solutions.com/wp-content/uploads/2022/05/PERI1216_LTR_White_Paper_v4b.pdf, Accessed 04 October 2024
Author: Shannon Horn, Commercial Business Director, Perimeter Solutions
Shannon Horn is the Commercial Business Director at Perimeter Solutions. He has worked in the fire safety business since 1991. He owned and operated three primary businesses (First Response Fire and Rescue, River City Fabrication, and H&S Transport) which supported the fire safety business, including service and equipment support since 2003. Perimeter Solutions acquired these three businesses in March of 2019. Shannon possesses a valuable sense of entrepreneurship, as well as a high level of athletic drive. He competes in triathlons worldwide and is a three-time National Champion and five-time All-American.
