Wiring Harness News WHN Sept-Oct 2020 WHN Sep-Oct 2020 - Page 35

INDUSTRIAL INFO-TAINMENT Wiring Harness News SEPTEMBER/OCTOBER 2020 35 either prevent a fire from starting in the first place or significantly slow a fire down. They are a popular choice because they do not significantly affect the extrusion process and are inexpensive. Other examples of halogens used in flame retardants include fluorine, chlorine and iodine. Non-Halogenated Flame Retardants Unlike halogenated flame retardants, which limit exothermic processes, non-halogenated flame retardants work by limiting endothermic processes, or how much heat is absorbed by the cable. Metal hydroxides are the most commonly used halogen-free flame retardants and work by employing three methods of flame retardancy: forming water vapor during combustion, reducing available organic fuel load or forming a protective layer of char. The advantage of non-halogenated cable constructions is that they generally emit less smoke and acidic gas than their halogenated counterparts, improving visibility and breathability during a fire and making it easier for people to find their way out to safety. For this reason, non-halogenated insulated cable should be used in enclosed areas where human life is at risk. They also have low levels of hydrogen chloride, a compound which is damaging to electronic circuits, making them the preferred cable construction in expensive electronic equipment rooms, such as telecommunications rooms and shipboard applications. The disadvantage of non-halogenated insulations is the considerable loadings of inorganics required. Loadings can be as high as 65 percent in the final product, which will affect the mechanical properties of the polymer. They also tend to be more expensive and may have inferior physical property performance compared to their halogen-based counterparts. As you can see, there are a few things that must be taken into consideration when selecting the correct insulation system for an application. Need help deciding which type of flame-retardant cable insulation is best for your application? Visit anixter.com/contact to get advice from one of our experts.