A Detailed Study of the Properties of Smoke Particles Produced from both Flaming and Non-Flaming Combustion of Common Mine Combustibles

Abstract

This paper presents the results obtained from detailed studies of the properties of smoke particles produced from a wide range of flaming and non-flaming combustible materials and discusses how these properties impact early-warning fire detection as well as the hazards of smoke particle toxicity and reduced visibility that can significantly affect life safety. Data acquired include discrete angular scattering at wavelengths of 635 nm and 532 nm; visible light obscuration; light extinction at a wavelength of 532 nm and total light scattering at a wavelength of 520 nm; the responses of calibrated combination ionization/photoelectric smoke sensor; and total mass concentrations. These data are subsequently used to define the size, morphology and radiative transfer properties of the fractal aggregate smoke particles including radius of gyration, primary particle diameter, number of primary particles per aggregate, mass of an aggregate, mass extinction, scattering and absorption coefficients and the resultant albedo. Scanning electron microscope (SEM)/transmission electron microscope (TEM) data and computer-generated fractal aggregates are compared to determine similar morphologies and then used to calculate theoretical values of scattering, absorption, and extinction efficiencies using both the discrete dipole approximation (DDA) and the Rayleigh-Debye-Gans (RDG) approximation for subsequent comparison to the experimental data. These data and analyses indicate that significant differences exist between flaming and non-flaming smoke particles in terms of size, morphology and radiative transfer properties. From a practical viewpoint, the analyses also indicate possible techniques for development of improved early warning fire sensors and smarter, discriminating fire sensors that can function in hostile, contaminated atmospheres such as mines and tunnels. These atmospheres may contain significant levels of combustion products from internal combustion engines, such as diesels, that are used routinely in underground mines. In addition, the much higher albedos measured for non-flaming smoke particles are indicative of significantly lower carbon content and higher levels of volatile organic compounds that have the potential for increased acute toxicity due to their higher reactivity. The paper demonstrates how the basic data can be used to implement improved fire detection systems and improve our ability to assess hazards resulting from potentially catastrophic mine fires.

Quantification of Optical and Physical Properties of Combustion-Generated Carbonaceous Aerosols (< PM2.5) Using Analytical and Microscopic Techniques

“…These data provide a unique and complete description of the physical properties of the differing fractal aggregates generated from flaming and smoldering fires. It should be noted that when calculating the fractal properties using the UCB device, the Rg was calculated using average Rg / dg ratios obtained from a previous study [17]. Also, constant values were used for D f , where for aerosols generated from flaming fires, D f = 1.85 was used, while for aerosols generated from smoldering fires, D f = 2.1 was used.…”

“…It has been observed that ionization-type smoke detectors respond better to the smaller diameter particles produced from flaming combustion, while the photoelectric-type smoke detectors respond better to the larger diameter particles produced from smoldering combustion [2, 14, 15, 17, 21]. Additional research conducted by NIOSH reveals that the ionization-type detector also shows a high response to smaller particles produced from the exhausts of diesel engines, while the photoelectric type detector shows a much lower response [11].…”

Experimental Evaluation of 79 and 300 GHz Radar Performance in Fire Environments

“…To understand the mechanisms of radar signal propagation through fire, it is necessary first to define what the actual physical content behind the general term “fire” is. As shown in [ 11 , 12 , 13 , 14 ], fire is composed of many different substances. For the most part, fire is a mixture of hot gases; the reaction also produces carbon dioxide, water vapour, light and heat.…”

Tenability analysis for improvement of firefighters’ performance in a methane fire event at a coal mine working face

“…Crews must make such decisions within minutes of fire discovery. Furthermore, while there is literature devoted to various measures that impact tenability, 14 there are few examples that take a comprehensive approach to tenability. The literature that does exist is largely outside of the US context and provides broad approaches without a methodology for determining tenability.…”