Margaret Simonson

Emissions from Fires Part II: Simulated Room Fires

Detailed quantitative characterization of the combustion gases from a series of room fires is reported in this article. Three simulated room fires were conducted with a test room containing a typical domestic fuel load of furniture including a TV-set. Two types of TV-sets were studied in the experiments, i.e. those containing fire retarded and non-fire retarded enclosure material. The measurement of the combustion gases included inorganic species and various organic species among them polychlorinated and polybrominated dibenzodioxins and furans, and selected brominated flame retardant agents. The detailed quantitative characterization of the combustion gases from the room fires forms a unique source of emission data for fire incidents in buildings. Chlorinated dibenzodioxins and furans were found in the combustion gases from all room tests. No brominated dioxins were found, however brominated furans were found. Further, the results from the room tests indicate that a TV-set treated with brominated flame retardants included in the fire load of a room fire does not necessarily increase the emission of bromine containing organic combustion products. The methodology applied for the sampling and analysis has been described in Part I of this series of articles.

Fire-LCA study of TV sets with V0 and HB enclosure material.

Abstract A novel Life-Cycle Assessment model (Fire-LCA) has been defined for the determination of the environmental impact of measures taken to attain a high level of fire safety. This study, which represents the first application of this LCA model, concentrates on a comparison between a TV with an enclosure manufactured with a flame retardant (FR) plastic (V0-rated high impact polystyrene, HIPS, typical for the US market) and one manufactured with a non-flame retardant (HB-rated HIPS, typical for the European market). A fire model has been defined based on international statistics, which indicate that use of V0 rated enclosure material essentially removes the risk of TV fires while approximately 165 TV fires occur per million TVs in Europe each year where the enclosure material is breached. The application of the model indicates that emissions of some key species (such as dibenzodioxins and PAH) are actually lower for the TV with the FR enclosure than for the TV with the NFR enclosure. This has direct reprercussions for the assessment of the environmental impact of the FR TV relative to that of the NFR TV. Finally, when considering the risk associated with the use of flame retardants, it is also important to consider the risk associated with fires. Based on the in-depth analysis of available fire statistics, conducted as a part of this study, it has been estimated that as many as 160 people may die each year in Europe as a direct result of TV fires and as many as 2000 may be injured in the same period.

Fire Emissions into the Atmosphere

The amount of various pollutants per year emitted into the atmosphere from fires in Sweden is estimated. The pollutants considered in detail are CO2, CO, HCN, NOx, SO2, HCl, unburned hydrocarbons, and particulate matter. The emission of N2O, aromatic hydrocarbons, dioxins, and heavy metals, is discussed qualititavely. The estimate is based on the number of fires in buildings and vehicles in Sweden a typical year. Emissions from wildfires have not been included.The results indicate that the amount of combustible material consumed by fire each year is approximately 12 kton, although it should be noted that during certain years, industrial fires may inflate this number. The emission of particulate matter and unburned hydrocarbons is approximately equivalent to that expected from the combustion of 2 Mton of solid fuel in a combustion plant, corresponding to energy production of approximately 15 TWh, which is of the same order of magnitude as that expected from heavy transport in Sweden each year. The emission of the other species studied is negligible relative to other sources. Measurements of species that have not been studied in detail (such as dioxins) under realistic conditions are necessary for determining the amount of these species emitted per year.

A theoretical investigation of the two lowest potential energy surfaces for the reaction C(3P)+NO (2Π)

Abstract The two lowest potential energy surfaces for C( 3 P)+NO( 2 Π) have been investigated. The stationary points were first located using CASSCF gradient calculations and the geometries reoptimized using complete active space second-order perturbation theory. Zero-point corrections have been included in the energetics. In addition to the three linear conformations CNO, NCO and CON, a previously unreported triangular conformation has been found. We found no barrier to carbon attack to the oxygen end of NO, leading to CON. This channel would lead to direct production of N+CO but is expected to be entropically disfavoured. No barrier to CNO formation has been found, in accord with experimental predictions. Experimentalists found no evidence of CO production and concluded that CN+O are the main products, but our investigation gives no reason to exclude formation of N+CO. It is suggested that the discrepancy may be due to the fact that no monitoring of CO production was performed.

Quasiclassical trajectory study of the C + NO reaction on a new potential energy surface

Abstract A new many-body expansion (MBE) fit of the A″ surface associated with the reaction of atomic carbon and NO is presented. Trajectory calculations, based on this surface, of the rate coefficients for the reactions C( 3 P) + NO(X 2 Π) k 1 CN(X 2 ∑ + ) + O( 3 P) and C( P ) + NO(X 2 Π k 2 CO(X 1 ∑ + ) + N( 2 D) are compared to experimental results over a range of temperatures from room temperature to combustion temperatures (200–4500 K). Quasiclassical trajectory (QCT) calculations based both on the MBE surface presented here and two LEPS surfaces previously presented by Halvick et al. [Chem. Phys. 131 (1989) 375] are employed to mimic the crossed molecular beam (CMB) experiments. Comparisons between CMB results and the trajectory calculations indicate that the reaction proceeds via a long-lived complex, although RRKM calculations produce lifetimes about an order of magnitude shorter than the trajectory calculations.

Small and Large Scale Fire Experiments with Electric Cables under Well-Ventilated and Vitiated Conditions

Results from a series of small scale (using the DIN 53 436 tube furnace) and large scale experiments (using the IEC 60332-3 rig) are presented for two types of power transmission cables used in buildings. The results are unique in that they catalogue the production of a wide variety of organic and inorganic species under different fire conditions. The experiments were conducted to provide input to an LCA model and the specific organic species studied in detail have been chosen based on the information required by the LCA model.During the process of this study it became apparent that information concerning quantitative organic species evolution from cable fires is lacking in the open literature. This paper aims to provide such information for two specific sets of fire conditions, i.e., a well-ventilated and a vitiated cable riser fire.

RRKM studies of product branching in the NH+NO reaction

Abstract We use RRKM theory to calculate rate constants and product branching fractions for NH+NO, comparing results for an ab initio surface and two recent empirical surfaces. In addition we compare trajectory and RRKM branching fractions based on the empirical surfaces, including an assessment of zero-point energy effects on branching. Our calculations show that the ab initio and empirical surfaces give similar branching, with results that are in good agreement with recent experiments. Trajectory and RRKM branching results are also close, but the HNNO lifetimes are not. Anharmonic effects are a possible explanation of this discrepancy.

THE CHLORINATING SPECIES IN TURBULENT FLAME COMBUSTION OF METHANE WITH HYDROGEN CHLORIDE PRESENT

Combustion of methane with air in the presence of hydrogen chloride was studied in a turbulent jet-stirred burner. The reaction was monitored by in situ mass spectometry and the ratio of Cl22HCl intensities was measured as a function of equivalence ratio (Φ). For values of Φ = 1.25 − 0.5 (fuel rich to fuel lean flames) the ratio of Cl22HCl intensities was close to zero. For values of Φ < 0.5 the ratio of Cl22HCl intensities increased significantly. The interpretation is that hydrocarbon radicals, e.g. CH, strip Cl from HCl to produce chloromethyl radicals which are known to react to form simple chlorocarbons, chlorinated aromatics, chlorinated PAH and Dioxins. For Φ < 1.0 no chlorination was observed.

Fire Performance of Selected IT-Equipment

The results from a series of large scale tests are presented to establish the fire performance of a number of common pieces of IT equipment including: computer monitors, printers and CPUs. The monitors have been tested in a fully furnished scenario in the ISO 9705 room arranged in a typical bedroom setting and in a specially constructed 4 m × 5 m room arranged in a typical classroom setting. The other pieces of equipment have been tested directly under the furniture calorimeter. This paper presents HRR for the various tests and discusses the significance of the results in terms of fire safety. A discussion of available statistical and anecdotal information is presented in this context.

Apparatus for studying premixed laminar flames using mass spectrometry and fiber‐optic spectrometry

An integrated flat‐flame/ microprobe sampling quadrupole mass spectrometer system, complemented by optical spectrometry based on optical fibers, is presented. The short microprobe sampling line (total 25 cm) is directly connected to an open ion source closely flanked by two nude cryopumps (900 l/s) yielding a background pressure of 10−9 Torr and a sampling pressure of about 10−5 Torr. Due to this improved microprobe system, mass spectrometry can be used for analysis of stable species (including fuel, O2, H2O, CO2, CO, and Ar) with less disturbance of the sample than with a conventional microprobe with a back pressure of about 1 Torr. Optical spectrometry is used for the study of emission from important radical species (such as C2, CH, and OH). The system is proposed as a complement to more conventional flat‐flame/MBMS systems in which the sampling cone can effect the experimental system. Details are provided concerning the configuration of the whole system ranging from gas delivery to data evaluation. Tes...