In the context of fighting the dramatic fires in Los Angeles (USA), these days some neighborhoods, land and even vehicles have appeared dyed with a peculiar red-pink powder, a substance spilled from seaplanes that mixed with water contributes to slowing down the spread of the flames.
This chemical compound called retardant helps the water poured to smother the flames take longer to evaporate and causes the combustion process to slow down when it reaches the flame front, as the firefighter from the Reinforcement Brigades in the city explained to EFE today. Forest Fires (Brif) Spanish Carlos Martín.
In general in forestry fighting, water evaporates “very quickly” due to the intense heat when fighting a fire and even more so in the conditions in which we are working these days in Los Angeles, with circumstances of “drought, wind and with low relative air humidity”.
The discharge of a firefighting helicopter can be between 1,000 and 1,500 liters on average over a burning bush, but in just “five minutes it can evaporate” due to the high temperatures without even touching the surface of the ground or the vegetation, the expert.
What type of retardants exist?
On the one hand, there are short-term retardants, which would be foaming agents, such as foams, which increase the insulating surface between the fuel and the heat and fire.
On the other hand, there are long-lasting compounds, which leave a red trail whose color intensity could vary depending on the amount of water in the mixture and the concentration levels.
These are chemical compounds, especially “phosphate salts, phosphates and polyphosphates, to which are added another series of additives that can be contaminants and even affect the land they reach.”
The retarders also include an anti-corrosion agent, to prevent the tanker of the air vehicles that transport them from rusting.
Why the color?
The red color is provided by a dye, included on purpose, to facilitate the visualization of the substance which, although it tends to disappear over time, is very useful in environments such as the forest environment to clearly mark the area where the retardant has been applied.
According to Martín, the compound, in addition to slowing down the evaporation of the water poured by seaplanes in the fight against fires, leaves a layer of polyphosphates on the surface it reaches and contributes to making combustion “much more difficult for the flame front.” “.
Are retardants used in fires in Spain?
As in other countries, in Spain it is common to use retardants in fires to extinguish them and to “consolidate a perimeter” in case there could be a possible future reactivation and a defense line could not have been made, or in very inaccessible areas.
In these cases, retardants help a lot to control the fire and to mark the area where the emergency services have been acting; As the brand looks, the color is visualized from above on the seaplane and helps to know the actions of colleagues in the fight against fires.
