3 Methods for Flame Retardant Systems — And How They Differ
Flame retardants are essential to slowing the spread of fire or preventing a fire from occurring in the first place. Since the 1970s, they have been used in many consumer and industrial products to minimize destruction to property and loss of life. Flame retardants are added or applied to a variety of products, including textiles, coatings, surface finishes, electronics and electrical devices, wire and cable, and insulation materials.
There are three methods for flame retardance:
- Vapor phase inhibition
- Solid phase char formation
- Quench and cool systems
Keep reading to learn the differences between the three and the best type of flame retardant to use for each method.
1) Vapor phase
Vapor phase inhibition is when flame retardant additives react with the burning polymer during the radical gas phase. These additives disrupt the production of free radicals, cooling down the system and reducing or suppressing the supply of flammable gases.
Brominated flame retardants (BFRs) are most often used for their vapor phase inhibition properties. Bromine releases active bromine atoms into the gas phase before the material reaches its ignition temperature. These atoms suppress the chemical reaction occurring within the flame, thereby extinguishing or slowing the spread of the fire. This gives residents or employees more time to escape the building or to extinguish the fire by other means.
SAYTEX® brominated flame retardants can improve the performance of your products and they suffer less deterioration of physical properties. They are available for a wide array of applications in many different industries.
2) Solid phase char formation
Solid phase char flame retardants promote char formation during a fire. These additives react with the burning polymer, creating a carbonaceous layer on the material’s surface. This layer serves as a protective barrier, which prevents the release of combustible gases and shields the underlying material from the heat of the flame.
The video below shows a vertical burn test performed with Elkem SIDISTAR® silicon dioxide — a flame retardancy synergist for thermoplastics. In the video, you can clearly see char forming on the surface of the material as it is subjected to fire.
Melamine-based flame retardants are known for their solid phase char functions. During the condensed phase, char stability is improved through the creation of cross-linked structures such as melem and melon. And when combined with phosphorus synergists, melamine can further enhance char stability through the formation of nitrogen-phosphorus substances.
3) Quench & cool systems
Quench and cool systems rely on hydrated materials to improve flame resistance. When exposed to fire, these hydrated minerals release water molecules to cool the substrate and interfere with the combustion process. These flame retardant compounds are often used for extruded applications like wire and cable.
Aluminum and magnesium hydroxides are compounds that can be used as quench and cool systems. Both of these compounds break down endothermically when subjected to high temperatures and release inter gases (like water vapor), diluting the combustible gases and reducing the chances of ignition.
There are many flame retardants to choose from and each product requires careful consideration before deciding. We can help you find the right system for your application. Contact us to discuss your unique needs.