Fire behavior of bed mattress on the viewpoint of flame-spread:-Experiments on conditions with different heights of mattress's installation

To understand the combustion behavior of a bed mattress on fire, a series of experiments was conducted by using a single-size pocket coil spring mattress at various installation heights above the floor (0-515 mm) according to ISO 12949. This paper reports the effects of the installation height on the bed mattress' combustion behavior through analysis of the flame spread burn area and flame height based on an existing calculation model. The experimental results revealed that a higher installation height of the mattress increased the fire growth rate and maximum heat release rate. Furthermore, the flame height increased as the flame of the burning mattress merged with the flame on the floor formed by melted mattress materials. Thus, the combustion behavior of the mattress is affected by its installation height and the combustion of its melted materials. The measured flame spread burn area on the bed mattress disagreed with the results calculated from applying the existing model for opposed-flow flame spread over a solid fuel. The combustion of the melted materials on the floor may have increased the difference between the measured and calculated results and accelerated the rate of the flame spread burn area on the mattress. Conventionally, the flame spread speed is determined by the incident heat flux (qf) at the upper surface of the mattress from the effect of radiation adjacent to the flame. However, a modified model is proposed where qf considers the effects from both the radiant heat flux by flame and convection heat flux by thermal air flow to the vertical section of the mattress. The results of the modified model were mostly consistent with the experimental results.