Ignition and flame spread theory is fundamental for evaluating the risk posed by a material during the early stages of a fire. This paper presents an experimental investigation aimed at understanding the parameters which govern the ignition of solids exposed to transient irradiation. Emphasis is placed on the conditions at ignition, including an energy balance to describe surface phenomena and the link between gas phase and solid phase processes. Experiments were performed in a fire calorimetry apparatus and incorporated a gas analysis system to study gas phase composition. Samples of Polyamide 6 (PA6) measuring 85 × 85 × 20 mm were used. Experiments were carried out to independently measure temperature in the solid phase and mass loss rate (MLR) over time. The MLR at ignition was calculated to be between 2.0 and 6.0 g/(m² s) for all but 3 experiments, were outliers presented values of 7.9, 10.7 and 14.4 g/(m² s). Temperature was recorded through the thickness of the solid, at depths of 4, 8, 12 and 16 mm from the surface. A regression analysis was used to calculate the surface temperature at ignition for all experiments, and it was found to vary between 270 and 325 °C for all but one experiment, were a temperature of 402 °C was recorded. The temperature distribution in the solid phase was used to estimate the net absorbed heat flux at the surface by applying Fourier’s law; with values ranging between 2.0 and 9.8 kW/m². From the gas analysis, it was possible to assess the identity, mass flux and concentration of three dominant species produced before ignition: carbon monoxide, methane and hexane. These results are of value for the physical modelling of ignition and flame spread phenomena, allowing for more accurate criteria to describe the onset of ignition under a range of heating conditions.

点火和火焰蔓延理论是评估火灾初期材料造成的风险的基础。本文提出了一项实验研究，旨在了解控制暴露于瞬态辐射的固体着火的参数。重点放在点火条件上，包括能量平衡以描述表面现象以及气相和固相过程之间的联系。实验是在火灾量热仪中进行的，并结合了气体分析系统来研究气相组成。使用尺寸为85×85×20 mm的聚酰胺6（PA6）样品。进行实验以独立地测量固相温度和随时间的质量损失率（MLR）。计算出点火时的MLR为2.0至6.0 g /（m ² s）除3个实验外，所有异常值分别为7.9、10.7和14.4 g /（m ²  s）。在距表面4、8、12和16毫米的深度处，通过固体厚度记录温度。使用回归分析计算所有实验的着火表面温度，发现除一个实验外，所有实验的温度在270至325°C之间变化，记录的温度为402°C。通过应用傅立叶定律，将固相中的温度分布用于估算表面的净吸收热通量。值介于2.0到9.8 kW / m ^2之间。从气体分析中，有可能评估点火前产生的三种主要物质：一氧化碳，甲烷和己烷的身份，质量通量和浓度。这些结果对于点火和火焰蔓延现象的物理模型具有重要价值，允许使用更准确的标准来描述在一定加热条件下点火的开始。