Flame-retardant wire burning behavior by jet flame heating: Ignition, charring, and secondary flame spread

This research presents an in-depth examination of the combustion characteristics of flame-retardant electrical wires, contrasting behavior with non-flame-retardant counterparts under jet flame heating. The study systematically investigates the pyrolysis process, ignition patterns, charring behavior, and the development of secondary flames in wires with different core diameters and insulation materials. Findings indicate the heightened susceptibility of thinner wires to rapid heating, pyrolysis and charring, leading to faster ignition and more intense secondary flame development. This insight is crucial for tailoring flame-retardant formulations to specific wire dimensions. The research also delves into the thermal dynamics within the wires, highlighting how the core diameter influences axial heat conduction and, consequently, the overall flame spread behavior and pyrolysis rate. A critical discovery is the relationship between heating duration and flame sustainability, establishing a specific range of heating times for sustaining secondary flames in flame-retardant wires. Theoretical models used in the study explained the critical heat flux heating time for wire ignition, offering insights into improved fire prevention strategies, particularly in prolonged heat exposure scenarios. These findings not only advance our understanding of flame-retardant wire behavior under fire conditions but also provide guidance for selecting and using electrical wires, thereby optimizing fire safety in diverse applications.