A study of ignition of timber by incandescent lamp

Abstract

In this article, a study is reported on the ignition of timber board by an incandescent light. A set of experimental tests were conducted to demonstrate the possibility of such an event. Inference was then made to the possible cause of a fire incident that occurred at a building construction site a few years ago. Theoretical analysis was also conducted based on an ignition model. The model is able to correlate the time to ignition with the distance between the light bulb with a given power output and the timber board.

Experimental and theoretical study of the ignition of timber by an incandescent lamp

“…Two sets of tests were conducted to estimate h. As shown in Figure 4(a), the radiant heat flux meter was placed horizontally just under the center of the incandescent light bulb in the first set of tests. In the second set, the whole apparatus was rotated 180°to consider the effects of heat convection, unlike in An's 3 research, where the effects of heat convection were ignored in the case of the radiant heat flux meter above an incandescent light bulb. Figure 3(a) shows the experimental radiant heat fluxes of two different operating conditions at the same distance.…”

“…Experimental procedures. Before the ignition experiments, paulownia wood samples of 200 3 200 3 20 mm 3 were placed in a 95°C and 50% humidity drying cabinet for more than 12 h to dry. To measure the radiant heat flux and temperature profiles on the sample surface, a radiant heat flux meter and a thermocouple (TC1) were placed at the same location on the sample surface, but the measurements were taken in separately repeated experiments.…”

“…Model of minimum incident heat flux to achieve ignition Heat and mass transfer occurs when a wood sample is subjected to a constant incident radiant heat flux. 3,6,7 Once the concentration of the combustible mixed gas is sufficient, and the critical temperature is reached, ignition occurs. The minimum radiant heat flux, which lies somewhere between the lowest incident heat flux, at which ignition occurs, and the highest incident heat flux, where ignition does not occur, 4 may be determined from a heat balance analysis of the wood surface, using the critical surface temperature.…”

“…Hence, it is reasonable to simplify the problem into one dimension with uniform heat flux. 3 The complete heat transfer process on the wood surface comprises radiation, convection, conduction, and gasification.…”

“…1 The State Key Laboratory of Fire Science, University of Science and Technology of China, determined that the fire cause was that an incandescent bulb ignited nearby wood materials. 1 Some research [1][2][3] has been conducted into the pyrolysis and ignition of wood exposed to heat flux from a clear glass envelope incandescent light bulb, and some ignition models have been established. Nonetheless, incandescent light bulbs are regarded as a point source in the calculation of radiant heat flux, which is insufficiently accurate.…”