Fire Safety Science Digital Archive

It has been established that the release of both thermal radiation and products of incomplete combustion from well-ventilated buoyant turbulent diffusion-flames are well-correlated by the fuel's laminar flame smoke-point value. Thus the smoke-point of a material provides an important measure of its flammability. Standard methods are available for measuring the smoke-points of gaseous and liquid fuels, but not for solid fuels. The apparatus developed for the present study can be used for measuring the smoke-points of charring and noncharring solid fuels. A horizontal fuel sample is continuously fed into a downward pointing CO, laser beam which pyrolyzes a small area of the sample. The heat release rate (or flame height) of the steady laminar flame produced by the pyrolysis gases is controlled by the laser beam power and/or the sample feed rate. The flame height is measured by a video camera while the release of smoke is measured by its attenuation of an electronically chopped infrared beam. The smoke-point is defined here by the critical flame height (or heat release rate) at which significant smoke is released from the flame tip. This smoke-point criterion occurs at considerably greater flame heights than the "equal-wings" condition, which previously has been used by some investigators to define the smoke-point.