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A number of large-scale fire experiments with detailed quantitative analysis

of polycyclic aromatic hydrocarbon (PAH) including PAH congener distribution

have been conducted by SP. This data is reviewed here and is further assessed with

regard to toxicity applying a Toxic Equivalency Factor (TEF) model for estimation

of cancer potential. The PAH yield data from the large-scale fire experiments is also

compared to emission factors from other combustion sources. The study shows that

full-scale fire experiments with different products exhibit a large variation in total

PAH yields. Fires with products containing flame retardants were shown to produce

the highest yields and generally a more toxic mixture of PAHs than fires with nonflame

retarded products. The distribution of individual PAH congeners is generally

quantitatively dominated by low molecular weight PAHs, whereas a small number of

medium to high molecular weight PAHs are most important in determining the toxicity

of the PAH mixture. The large-scale fire experiments indicate that fires normally

produce orders of magnitudes higher yields compared to, e.g. modern residential

combustion devices. The relative distribution of individual PAHs, which determines

the toxicity of the PAH mix, is similar for the fires and open burning data studied, in

that benzo(a)pyrene and dibenz(a,h)anthracene dominate the toxicity of the mix as a

whole.

Combustion behaviour of municipal solid waste bales is a rarely studied topic hitherto. However, there is dire need to devote research on the topic because baling as a storage methodology is getting popular among waste management companies and fire episodes in such storage sites can have devastating economic, environmental and social implications. In this study, thickness of low density polyethylene (LDPE) plastic sheets (12 layers, 6 layers and no layer) and type of ignition source (pilot ignition, thermal radiation) were investigated to see their effect on combustion behaviour of bales. In total eleven tests with a single bale in each test were performed. It has been found that the bales not wrapped with LDPE plastic sheets may pose higher hazards for adjacently stored material to catch fire as the value of maximum heat release rate observed for them was higher than those wrapped with LDPE plastic sheets. Furthermore, it has been found that LDPE plastic wrapping do not contribute significantly to the combustion of bales when exposed only to thermal radiation from an adjacent fire. However, it plays a significant role in ignition of bales in case exposed to a pilot flame ignition source. Molten LDPE plastic trapped between the adjacently stored bales was found to be another important factor influencing the combustion of bales.

Results of a simple flow model to describe the entrainment into the air cone created by a positive pressure ventilator (PPV) fan are compared to experimental data. Velocity profiles measured in the air cone of a conventional PPV ventilator are used. The entrainment coefficient and the cone angle were determined for the fan investigated. The correspondence between calculated and measured values is discussed and disparities explained. The findings from the tests are turned into practical guidance for the fire brigade and the advantages and limitations of the simplified model are discussed.

Theoretical analyses and model-scale experiments have been conducted to investigate the critical velocity in a tunnel cross-passage which is defined as the minimum ventilation velocity through the fireproof door to prevent smoke from flowing into a cross-passage. The effect of the fireproof door geometry, heat release rate, ventilation velocity and fire source location were taken into account. The critical velocity in a tunnel cross-passage varies approximately as three-second power of the fireproof door height, as one-third power of the heat release rate and as exponential law of the ventilation velocity, almost independent of the fireproof door width. The critical Froude Number range varies mainly between 5 to 10 and consequently as it is not a constant value it is not very suitable to predict the critical velocity in a tunnel cross-passage. A dimensionless correlation that can correlate well with the experimental data was proposed

The existing theoretical modelling of thermoacoustic oscillations has been

studied and applied to the case of tunnel fires. The assumptions of the theoretical

model were reviewed. It was found that several assumptions are not applicable to

tunnel fires and, hence, suggestions for improvement are given. The correlation which

expresses the starting conditions for thermoacoustic oscillations is analysed and

dependencies on different parameters are presented. The pulsations documented during

the large-scale tests in the Runehamar tunnel in 2003 have also been further analysed.

The measurements were compared to the theoretical limiting curve for

oscillations, showing good agreement. To further study thermoacoustic oscillations in

tunnels, more detailed tests in a model-scale tunnel (1:100) were performed. These

tests focused on the circumstances which are required to create thermoacoustic oscillations,

i.e. the fire was located at different positions along the tunnel and the air flow

rate was varied. The tunnel had a length of 4 m, was 8 cm wide and 6 cm high. The

results were in good accordance with the theoretical modelling but showed deviations

which were most obvious at very low and high air velocities. Both the starting conditions

for thermoacoustic oscillations and cases where the thermoacoustic oscillations

suddenly stopped, were observed. These findings led to identification of several points

in the theoretical model which need to be improved, and to the development of a

strategy to avoid such pulsation in fires.

The paper describes full-scale fire-fighting tests performed in an underground mine. A total of six different methods to fight a full scale fire in a mine tunnel were tested. The methods involved different fire-fighting equipment but were comparable regarding fundamental conditions such as length of response-route, fire-fighting set-up, and smoke and fire size. The aim was to compare different equipment and methods to reach and eventually extinguish the fire. Fire fighters using breathing apparatus (BA) were monitored regarding air consumption, movement speed and local actions and decisions. The results are presented and analyzed in respect to fire-fighting efficiency, front BA operations including moving speed and performed actions, as well as the time to successfully put out the fire. Measurements of heat release rates, temperatures and moving speeds are given in order to quantify the efficiency of the operation. Results indicate that a timespan of 15-30 min is needed for the firefighters to reach the fire source and achieve the extinguishing criteria in five of the tests. The standard equipment and nozzles shows good performance in the tests. A limiting factor on the firefighter's endurance is the amount of air that is available. As a result from these findings the endurance of BA-teams could improve if focus is put on team organization, lightweight equipment and air supply.