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- Fire debris (2)
- Ignitable liquids (2)
- Arson analysis (1)
- Brandfrüherkennung (1)
- Brandmelder (1)
- Cone calorimeter (1)
- Crime (1)
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- Fire chemistry (1)
Durch die Verwendung von Grillgeräten in geschlossenen Räumen, wie Gartenlauben, Wohnungen oder Garagen kam es in den vergangenen Jahren zu einer Vielzahl von Unfällen mit schweren Vergiftungen und Todesfällen. Seit 2008 scheint das Auftreten von Kohlenmonoxid (CO) Intoxikationen innerhalb Deutschland wieder zu zunehmen. Die Hauptursachen sind dabei der unsachgemäße Gebrauch von Holzkohlegrills, schlecht gewartete Gasthermen und Kamine. Zum Schutz der Bevölkerung ist deshalb eine Aufklärung über mögliche Gefahren wichtig.
Im Rahmen dieser Arbeit wurden diese Gefahren bewertet. Es wurden verschiedene Brandszenarien mit Grillgeräten, mit unterschiedlichen Grillkohlearten und –mengen in geschlossenen Räumen realisiert und die entsprechenden Konzentrations-Zeit-Verläufe ermittelt. Bei den Brandversuchen wurden zudem notwendige Eingabeparameter für numerische Simulationen ermittelt, um die Verwendung von Holzkohlegrills in geschlossenen Räumen zu simulieren. Die Auswirkungen für Menschen beim Grillen in geschlossenen Räumen wurden quantifiziert, indem die Eintrittszeitpunkte der Handlungsunfähigkeit und des Todes mittels Fractional Effective Dose (FED)-Konzept bestimmt wurden. Die Ergebnisse zeigen deutlich, dass eine frühzeitige Detektion der toxischen Gase zur Warnung von Personen dringend notwendig ist. In den durchgeführten Brandversuchen zeigte sich, dass die gebräuchlichen Rauchmelder auf Streulichtbasis keine rechtzeitige Warnung ermöglichen. Deshalb sind für solche Brandszenarien andere Branddetektoren erforderlich. Entsprechende Versuche mit CO-Brandmeldern zeigten, dass das freigesetzte CO beim Grillen in geschlossenen Räumen frühzeitig detektiert werden kann und Personen somit rechtzeitig gewarnt werden können.
Zur frühzeitigen Erkennung von Schwelbränden wurde weiterhin ein neuer Wasserstoffdetektor getestet. Die Entstehung von Wasserstoff in einer sehr frühen Brandphase kann zur frühzeitigen Erkennung von Schwelbränden genutzt werden. Bei ersten Schwelbrandexperimenten mit Holzproben konnte Wasserstoff in einer geschlossenen Kammer (0,5 m3) nachgewiesen werden, noch bevor es zu einer erhöhten CO-Emission kam. Die Ergebnisse der Schwelbrandversuche werden vorgestellt und die Verwendbarkeit von CO- und Wasserstoff-Detektoren erörtert und diskutiert.
We analysed the hydrogen generation during the smouldering of polymeric materials, which are typically used in the household, in the Smoke Density Chamber coupled to a new developed hydrogen sensor to detect early stages of fires. The results of hydrogen generation were compared with the emission of carbon monoxide and smoke during the fire scenarios. Additionally, the results were compared with parameters used in traditional commercial detection systems. In this scenario, the hydrogen sensor showed encouraging results for the detection of fires in earlier phase compared to traditional detectors. Furthermore, we tested the new developed hydrogen sensor in a real room with different fire scenarios. We have also investigated interferences, e.g. steam and cigarette smoke. The hydrogen sensor could detect hydrogen generation in the earliest stage of fire, even before CO and smoke were developed in detectable amounts. Therefore, the hydrogen sensor can be applied for early fire detection in case of pyrolysis. The sensors are quite good for detecting pyrolysis gases. But when it comes to a fast ignition other techniques are more suitable for it. The sensors are best for combination with other techniques, such as smoke detectors.
The chemical analysis of fire debris represents a crucial part in fire investigations to determine the cause of a fire. A headspace solid-phase microextraction (HS-SPME) procedure for the detection of ignitable liquids in fire debris using a fiber coated with a mixture of three different sorbent materials (Divinylbenzene/Carboxen/Polydimethylsiloxane, DVB/CAR/PDMS) is described. Gasoline and diesel fuel were spiked upon a preburnt matrix (wood charcoal), extracted and concentrated with HS-SPME and then analyzed with gas chromatography/mass spectrometry (GC/MS). The experimental conditions—extraction temperature, incubation and exposure time—were optimized. To assess the applicability of the method, fire debris samples were prepared in the smoke density chamber (SDC) and a controlled-atmosphere cone calorimeter. The developed methods were successfully applied to burnt particleboard and carpet samples. The results demonstrate that the procedure that has been developed here is suitable for detecting these ignitable liquids in highly burnt debris.
Based on forensic evidence, a smouldering fire was observed to have occurred at a murder scene. Identification of a reasonable timeline – specifically the fire dynamics of the ignition and fire growth that occurred coincident with the death that took place – became an important focus of the criminal investigation that followed. The fire service was called when a neighbour saw a grey smoke escaping through the ventilation system of the bathrooms on the roof of the house. One flat door with elevated temperatures was found. The fire fighter who entered the flat first reported later that the flat was completely filled with smoke and all windows were closed. When the fire fighter opened the balcony door, he saw flames on the sofa that he extinguished. Then he found a body on the floor. The autopsy showed later that the victim was dead before the fire started. The police suspected that the murderer probably had deliberately set the fire to destroy evidence. One suspect had been witnessed to be in the flat approximately 2 h before the fire was detected by the neighbour. The aim of this project was to investigate how the fire most likely started and developed.
Reconstructing the course of a fire and performing chemical analysis of ignitable liquids in fire debris is an important tool to conduct fire investigations in suspected arson cases. Here, a total of five fire tests has been performed to investigate the effect of fire accelerants on the fire development of a room fire and to prove the capability of analytical methods. Different experimental scenarios have been realized (no accelerant, accelerant applied at different positions, and different amounts of fire accelerant). Each test room was equipped with an identical set of living room furnishing. The location and amount of the fire accelerant applied löschen varied in four of five tests. One experiment was carried out without fire accelerant. Fire quantities such as mass loss (of the entire room), gas temperatures (at several locations in the room), and heat release were determined during the experiments, and chemical-analytical studies were carried out. A headspace solid phase micro extraction procedure, using gas chromatography–mass spectrometry, was used to analyze fire debris samples to potentially detect ignitable liquids. Beside the analysis of fire debris samples, swipe soot samples were analyzed and the detectability of the fire accelerant used was demonstrated. Results show that it is possible to provide evidence of ignitable liquids in soot samples collected from walls. This allows an additional sampling strategy at potential crime scenes, besides taking fire debris samples.
The Federal Institute for Risk Assessment (BfR) DocCenter has received more and more reports of cases of carbon monoxide (CO) poisoning, some even with fatal outcomes after indoor use of charcoal grills. CO is odorless, colorless, non-irritant and does not produce any other warning effect perceptible to humans. The BfR and the Federal Institute for Materials Research and Testing (BAM) have completed a cooperative research project to investigate the toxic concentrations of CO that are reached when charcoal grills or open fires are used indoors.