By using a deep scientific understanding of fire, fabric manufacturers have developed strategies for FR Protecting Cover Fabric that are focused on removing one of the components required to sustain the fire. All of these technologies are designed to snuff out a flame and mitigate the risk of injury for the wearer, but each of them has their own set of advantages. Since each of the technologies can be made permanent for the life of the protective garment and will not wash out with laundering, the selection of the technology will depend on the specific hazard and the preference for other attributes.There is not a technology that is best for all hazard situations.
For example, an electrical worker who may be exposed to an electrical arc flash hazard, a petrochemical worker who is exposed to the risk of flash fire and a firefighter who is exposed to a longer duration fuel-fed fire may all require different technologies to their FR protective clothing. While taking into account industry requirements, work environments, comfort and employee preferences, manufacturers create FR fabrics that are both tailored to thermal hazards that may be present on the job site and that offer consistent protection day-in and day-out.There are three technologies that are commonly used to create FR fabrics: char-forming agents, gas-phase radical scavengers and high-temperature fibers.Char-forming agents are phosphorous-based fire retardants that can be incorporated into fibers or fabrics.
They are primarily used with cellulose fibers such as cotton, rayon or lyocell. When these fabrics are exposed to fire, and the fibers begin to break down into gaseous fuel, the phosphorous agent reacts with the fuel molecules to form a stable, solid char. The char not only consumes the gaseous molecules, which would otherwise be fuel for the fire, but also creates a barrier between the flame and the fabric and prevents the fabric from further breaking down and releasing more fuel. Therefore, these FR agents form flame resistant materials by depriving the fire of one of its four necessary ingredients, in this case, fuel.These FR agents can be incorporated into synthetic cellulosic fibers during fiber formation or engineered onto fibers after fabric formation.
The engineering process involves saturating the fabric with the phosphorous-based FR agent solution, and then conducting a chemical reaction to form durable bonds that results in a permanently flame-resistant fabric. The engineering process allows the fabric to retain its original look and comfort benefits that are so desired in cotton and rayon fabrics, while providing permanent FR protection against short-term thermal hazards.Another technology for suppressing flame is the gas-phase radical scavengers. These are special molecules, usually chlorine-based, that are part of the fiber structure and have the unique property of forming relative stable radicals when exposed to heat. Recall that the fuel must break apart into radical molecules in order to react with oxygen. As these fuel radicals are formed, they will combine with the chlorine radicals instead of oxygen and become trapped or “scavenged”. This deprives the fire of the chemical chain-reaction that is one of the required components to maintain a flame.