FIRE-TROL and PHOS-CHEK fire retardants have been produced for almost 60 years by a company whose name and ownership have changed five times since 1997 — starting with Monsanto in 1963, then Solutia, Astaris, ICL, and finally in 2018, Perimeter Solutions.
Today a new generation of fire retardant in the PHOS-CHEK line was introduced by Perimeter Solutions — LCE20-Fx. It is the result of two years of work by the Perimeter Solutions R&D team in Rancho Cucamonga, CA. Apparently very little time was spent choosing a name.
It was tested during the 2020 fire season, applying the required 200,000 gallons before it was approved by the Forest Service and added to the qualified products list on November 5, 2020.
“We will begin deploying this commercially next fire season at probably eight or nine bases, which we will convert from LC-95A to this new LCE20-Fx product,” said Edward Goldberg, Chief Executive Officer of Perimeter Solutions.
The new formulation has shown improvements in three key areas: coverage, visibility, and toxicity.
The retardant is produced as a liquid concentrate and delivered to application sites as a low-viscosity liquid. Before being loading onto an air tanker, it is diluted and mixed with water using an in-line proportioner as it is transferred to delivery systems. According to the company, the elastic nature of the gum thickener in LCE20-Fx reduces drift, dispersion, and evaporation, while increasing coverage, wrap around, and canopy penetration, making it more effective in targeting ground vegetation.
The reason fire retardants are red is so aerial firefighters can see exactly what areas of a fire have been treated. This reduces repeated drops in the same area and makes it possible for additional drops to tag on to and extend the treated areas along the edge of a fire.
“We’re utilizing Fx, the ultra high visibility pigment in our products, which helps the pilots see where they need to tie in the next line so that the fire doesn’t get through the gap,” said Melissa Kim, Director of Research and Development for Perimeter. “It just continues on with our line of Fx products. We started with iron oxide, then we moved to a fugitive, and then we improved on that fuchsia color. This product will fade over time, but it does have a high, extremely high, visibility to the point where we’ve had comments come back saying that it’s even more visible than our iron oxide products. So that was a big big deal for us.”
The reports about the visibility came after the new formulation was used this year at two air tanker bases in Nevada — Battle Mountain for most of the season, and Stead/Reno at the end of the season.
They will also be producing an uncolored version without any red or fuchsia pigment which could be applied from the ground by utilities or homeowners for long term prevention and protection.
The millions of gallons of red fire retardant that air tankers drop every year are usually made from ammonium phosphate or its derivatives. It has been called “long term fire retardant” because even after it dries, the chemical can interfere with the combustion process and may still retard the spread of a vegetation fire. However research and experience in the field has shown some formulations can be toxic to fish. Federal interagency policy prohibits the aerial delivery of retardant within 300 feet of certain waterways. It also cannot be used in certain designated terrestrial areas, or in some National Parks without special permission. The restrictions still apply to the new formulation of retardant introduced today.
Maps are available which identify threatened, endangered, candidate, proposed, and sensitive species (TECPS) avoidance areas. There appears to be significant variability within the Forest Service on interpreting the guidelines and mapping the areas.
The retardant products used by the U.S. Forest Service are tested for fish toxicity to determine the concentration in milligrams per liter (mg/L) that result in the death of 50 percent of the aquatic test specimens, young rainbow trout, within 96 hours. The higher the number, the less toxic it is. The Forest Service specifications for retardant require that the aquatic toxicity be greater than 200 mg/L. The previous versions of PHOS-CHEK, LC-95A, had toxicity levels of 225 to 399 mg/L. The new LCE20-Fx is 983.
The weight of the mixed LCE20-Fx retardant is slightly less than the previous generation, reducing the weight of a gallon from 9.01 pounds to 8.87 pounds, a savings of 0.14 pound per gallon. This reduces the weight of the 9,400 gallons on a DC-10 by 1,316 pounds, and of the 3,000 gallons on a BAe-146 by 420 pounds.
Transportable retardant plant
The Forest Service refers to them as “portable retardant bases”, but transportable is probably a more accurate term. Since these types of bases became an issue in discussions about the closure and dismantling of the tanker base at West Yellowstone, Montana, I asked Mr. Goldberg about their transportable equipment. He explained that the company has 12, each of which can be set up in as little as two hours once on site. They are not always in the same place and can be prepositioned depending on fire activity.
This article was first published at Fire Aviation.