Prediction of Flame‐Spread on Horizontal Combustibles

ABSTRACT The flame spread behavior of horizontal combustibles such as pocket coil mattresses in residential houses was investigated under various installation height conditions, and an existing predictive model was refined. In a series of experiments, mattresses were tested with diverse installation heights (ranging from 0 to 515 mm) using the standard ignition source specified by ISO 12949:2011. The experimental results revealed that both the fire growth rate and the maximum heat release rate increased with higher mattress installation height. During combustion, molten material and mattress fragments descended and ignited on the floor. The flames associated with the combustion on the floor affected the combustion of the mattress body, leading to a correlation between higher mattress installation height and increased heat release rates and fire growth rates. Traditionally, flame spread speed is determined by the incident heat flux to the horizontal and upper surfaces of the solid combustible material adjacent to the flame. However, a modified model was proposed that accounts for the influence of both convective and radiant heat fluxes generated by the flames on the floor, impacting the cross‐section of the burning mattress body.