In the past, you may have heard people talking about so-called ‘fire retardants’. But what does this term mean? How do they work?
What’s a Fire Retardant?
Breaking this phrase down, the word ‘retardant’ means inhibiting or preventing something from happening. Although it’s mostly used with regard to fire, it describes the process of prevention or limitation. Therefore, you’ve probably guessed that fire retardants are designed to either prevent a fire or stop it from spreading.
Once a fire starts, a fire retardant is used to either stop the spread, slow down the spread, or reduce the intensity of the flames. Depending on the cause and state of the fire, there are two ways to achieve one of these three goals:
- Physically
- Chemically
Physical Action
While many different physical actions prevent the spread of fire, three are more common than others.
1. Prevent igniting the underlying material by creating a protective layer.
2. Dilute the radicals using carbon dioxide and water (or just one).
3. Cooling the material and removing heat.
As you may have noticed, the purpose of these three physical actions is to remove one of the three things a fire needs to keep burning. While the first method removes fuel, the second removes oxygen while the third removes heat. By removing one of these elements from the fire, it loses power and cannot spread as quickly.
Chemical Action
On the other hand, some fire retardants rely on chemical action to limit or stop the spread of fire. As an example, intumescent solutions are sometimes used. With this, the chemicals contained in the solution react to the heat of the fire, swell, and provide insulation. Often, this solution is included in steel structures and wooden buildings to limit damage should a fire break nearby.
Elsewhere, you may find retardants designed to react in the gas phase as well as the solid phase. When the fuel is carbon-based, it’s possible to form carbonaceous char layers. Since these are harder to burn (or at least take longer), this slows the spread of fire.
Importance of Fire Retardants
Unfortunately, fire still tears apart families, communities, and even cities and countries every single year. Fire retardants are important because they form the basis of many fire-fighting techniques. As a basic example, you’ve probably seen thousands of fire extinguishers in your time. All rely on the properties of fire retardants to slow the spread of fire or eliminate it.
Earlier, you saw that fire retardant is included in products to provide a protective surface layer, and this is another important use. Every year, some homeowners risk a fire in their home by erecting a Christmas tree and not keeping it sufficiently watered. The lights get hot, the tree isn’t moist enough, and it sets fire. More and more, Christmas tree providers sell trees that have been sprayed with retardants.
As well as fire extinguishers and surface coating, fire retardants are also critical when fighting forest fires and other natural events, so make sure you test and tag yours annually. When a forest fire breaks, special planes take to the sky and drop retardants over the area to attempt to limit the spread. Generally, the planes will drop the retardants around the edge. From here, the ground team has time to set up and attack the flames. In some circumstances, however, planes will drop retardants directly onto the fire.
What are fire retardants? They’re a substance designed to slow the spread of a fire or reduce the intensity. How do they work? By creating a physical or chemical action.
