Analysis of a soldered wire burnt in a fire

Fire investigators frequently encounter electrical wires with melted ends at fire scenes, which can provide useful information on the cause and development of the fire even when the melted ends result from the fires. A bead on a melted end of a wire was found in the area of origin of a massive fire that lasted for nearly a whole day, devastating a factory. The bead appeared to be the end of a wire soldered to a terminal. X-ray analysis showed that the bead is a tin-copper alloy. Although regular tin-lead solder was used in the factory, lead was not detected. This contradictory result stood in the way of fire investigation. Therefore, an unused wire soldered with tin-lead solder was heated in an electric furnace at 500 degrees C for 3 h for further examination. X-ray analysis of this wire showed that copper can be alloyed with tin while losing lead in a long-term heat in a fire.     

Using fire dynamics simulator to reconstruct a hydroelectric power plant fire accident

The location of the hydroelectric power plant poses a high risk to occupants seeking to escape in a fire accident. Calculating the heat release rate of transformer oil as 11.5 MW/m(2), the fire at the Taiwan Dajia-River hydroelectric power plant was reconstructed using the fire dynamics simulator (FDS). The variations at the escape route of the fire hazard factors temperature, radiant heat, carbon monoxide, and oxygen were collected during the simulation to verify the causes of the serious casualties resulting from the fire. The simulated safe escape time when taking temperature changes into account is about 236 sec, 155 sec for radiant heat changes, 260 sec for carbon monoxide changes, and 235-248 sec for oxygen changes. These escape times are far less than the actual escape time of 302 sec. The simulation thus demonstrated the urgent need to improve escape options for people escaping a hydroelectric power plant fire.     

Extraction, derivatization, and analysis of vegetable oils from fire debris

Vegetable oils have the ability to spontaneously heat under certain conditions, which may lead to spontaneous ignition. While the oils are not often encountered in forensic casework, they may be suspected in some fire cases. As these oils are not effectively analyzed using traditional fire debris analysis methods, a protocol must be established for extracting vegetable oils from fire debris. In this study, a protocol was developed for the extraction, derivatization, and analysis of vegetable oils from fire debris. Three derivatization methods were compared to establish an optimal derivatization procedure to convert the fatty acids found in vegetable oils to the fatty acid methyl esters (FAMEs) used in analysis. Three different gas chromatograph columns and programs were examined to determine which was best suited for the separation and analysis of FAMEs. The procedure was tested and refined using a variety of neat and burned vegetable oils, in addition to extractions from oils burned on commonly encountered fire debris materials. The findings of this research will serve as a starting point for further understanding and research of vegetable oils in fire debris.     

The application of NIST's Fire Dynamics Simulator to the investigation of carbon monoxide exposure in the deaths of three Pittsburgh fire fighters

A case is reported in which computer fire modeling was used to reevaluate a fire that killed three fire fighters. NIST's Fire Dynamics Simulator (FDS) was employed to model the fire in order to estimate the concentration of carbon monoxide present in the dwelling, which was the immediate cause of death of two of the fire fighters, who appear to have removed their face pieces in order to share available air. This estimate, along with an assumed respiration volume and known blood carboxyhemoglobin, was plugged into a standard equation to estimate the time of exposure. The model indicated that 27 min into the fire, the carbon monoxide concentration had already reached approximately 3600 ppm. At this concentration, and a respiration of 70 L/min, an estimated 3 to 8 min of exposure would have been required to accumulate the concentrations of carboxyhemoglobin (49, 44, and 10%) measured on the fire fighters at autopsy.     

Correlates of adolescent fire setting: examining the role of fire interest,fire-related attentional bias,impulsivity, empathy and callous–unemotional traits

Little is known about potential correlates of problematic fire setting that could guide risk assessments and intervention. The current study measured aspects of fire-setting behaviour, fire interest, attentional bias towards fire-related words on a modified Stroop task, impulsivity, cognitive and affective empathy and callous–unemotional traits among adolescent fire setters, non-fire-setting antisocial adolescents and age-matched school controls. Results showed that current fire setting was associated with earlier onset of lighter/match play and unsanctioned fire setting. Fire-setting adolescents were also characterised by high impulsivity, callousness, uncaring traits and low cognitive empathy. Fire-setting frequency was best predicted by high impulsivity. Fire interest correlated negatively with accuracy on fire-related words on the fire Stroop task. These findings suggest that impulsivity may be important in the assessment and treatment of problematic fire setting, and encourage further research on modified Stroop tasks as a novel means to assess fire interest.     

Examination of misconceptions surrounding fatal fire victims

Fire deaths are not unusual in forensic investigative practice but due to the destructive nature of fire they are often very difficult to investigate. With the need to identify the deceased and the events surrounding the manner and cause of death, knowledge of thermally induced alteration to the human body is important. Within the fire investigation community, a number of misconceptions have been present for years regarding the protrusion of the tongue as an indicator of life during the fire, and fractured skulls as the result of brains boiling and skulls exploding. This work presents qualitative analysis on the experimental burning of 42 unembalmed human donated cadavers by the San Luis Obispo Strike Team (SLOFIST) on their annual Forensic Fire Death Investigation Course (FFDIC) between 2017 and 2019. Prior to burning, the position of the tongue within the dental arch was confirmed and sharp, blunt, surgical and gunshot trauma to the cranium documented. Temperature was recorded from ignition through to suppression with thermocouples present both within the scene and the body. Post burn analysis on the position of the tongue, observation of cranial fractures and presence of brain tissue were recorded and analysed in conjunction with thermocouple data, fire scene dynamics and body demographics. The results provide a more comprehensive understanding of the thermal environmental factors involved in producing the phenomena that facilitate these misconceptions, identifying that a more thorough understanding of individual fire scenes and their development is essential when interpreting alteration and injury to the body of the fatal fire victim.     

钢结构建筑的火灾危险性和防火保护

钢材是本世纪最为创新的建筑材料，在高层建筑钢结构、大跨度空间钢结构、轻钢结构等当今现代建筑工程中有广泛应用及发展前景。钢材虽为非燃烧材料，但钢不耐火，温度为400℃时，钢材的屈服强度将降至室外温下强度的一半，温度达到600℃时，钢材基本丧失全部强度和刚度。本文介绍了钢结构的火灾危险性、钢结构的火灾灾害等，指出钢结构防火保护的重要性及目前现有的几种钢结构防火保护方法，并着重介绍了防火涂料对钢结构的防火保护。     

A review of the analysis of vegetable oil residues from fire debris samples: analytical scheme, interpretation of the results, and future needs

This paper reviews the literature on the analysis of vegetable (and animal) oil residues from fire debris samples. The examination sequence starts with the solvent extraction of the residues from the substrate. The extract is then prepared for instrumental analysis by derivatizing fatty acids (FAs) into fatty acid methyl esters. The analysis is then carried out by gas chromatography or gas chromatography-mass spectrometry. The interpretation of the results is a difficult operation seriously limited by a lack of research on the subject. The present data analysis scheme utilizes FA ratios to determine the presence of vegetable oils and their propensity to self-heat and possibly, to spontaneously ignite. Preliminary work has demonstrated that it is possible to detect chemical compounds specific to an oil that underwent spontaneous ignition. Guidelines to conduct future research in the analysis of vegetable oil residues from fire debris samples are also presented.     

A solid-phase microextraction method for the detection of ignitable liquids in fire debris

A solid-phase microextraction (SPME) procedure involving direct contact between the SPME fibers and the solid matrix and subsequent gas chromatography/mass spectrometric analysis for the detection of accelerants in fire debris is described. The extraction performances of six fibers (100 mum polydimethylsiloxane, 65 mum polydimethylsiloxane-divinylbenzene, 85 mum polyacrylate, 85 mum carboxen-polydimethylsiloxane, 70 mum Carbowax-divinylbenzene, and 50/30 mum divinylbenzene-Carboxen-polydimethylsiloxane) were investigated by directly immersing the fibers into gasoline, kerosene, and diesel fuel. For simulated fire debris, in the direct contact extraction method, the SPME fiber was kept in contact with the fire debris matrix during extraction by penetrating plastic bags wrapping the sample. This method gave comparable results to the headspace SPME method in the extraction of gasoline and kerosene, and gave an improved recovery of low-volatile components in the extraction of diesel fuel from fire debris. The results demonstrate that this procedure is suitable as a simple and rapid screening method for detecting ignitable liquids in fire debris packed in plastic bags.     

Performance testing of commercial containers for collection and storage of fire debris evidence

Fire debris evidence may contain ignitable liquid residues valuable in the investigation of a potential arson scene. The ability to obtain evidence containers that are contaminant-free and vapor-tight is essential to the analysis and storage of fire debris evidence. Commercial containers such as metal "paint" cans, glass mason jars, and polymer bags are often employed as fire debris evidence containers. The purpose of this research was to determine which of these three types of containers provided the most vapor-tight seal for the prevention of ignitable liquid vapor loss and to assess the potential for cross-contamination. Leak rates for each type of container were measured under controlled conditions. Simple mixtures of hydrocarbons were utilized in these experiments. Leak rates were determined based on the amounts of hydrocarbon recovered from activated charcoal located outside the test container and within a secondary container. Quantitation of the hydrocarbons recovered from activated charcoal was calculated using external standard calibration curves following analysis by gas chromatography-mass spectrometry. The results demonstrated that glass jars had the fastest leak rate followed by metal paint cans and properly heat-sealed polymer bags with the slowest leak rate. Each container exhibited a different leak mechanism, which resulted in an observable effect on the composition of hydrocarbons lost from the container. Hydrocarbon transfer from one container to another is also demonstrated. This study presents results that reveal the most vapor-tight container to be a properly heat-sealed copolymer bag.     

152例火场尸体的法医学检验分析

目的 探讨火场尸体的法医学检验特点及其鉴定。方法 对86起火场中152例尸体的相关检验资料进行回顾性研究。结果 152例火场尸体,生前烧死109例,纵火焚尸38例,无明显高温作用的尸体5例。主要死因有“烧死综合征”100例,火场有毒气体中毒8例,机械性损伤32例(含高坠死4例),机械性窒息5例,电击、服毒各1例;不能确定死因5例。自杀5例,他杀40例,意外107例。在生前烧死尸体,87例呼吸道内有炭末沉着,71例皮肤局部烧伤边缘组织有红肿,46例检见水泡,17例有“闭眼反应”征象,大部分尸体血中HbCO浓度超过20％;纵火焚尸少见或不见上述改变。结论 检验火场尸体,根据烧死尸体征象和血中HbCO浓度检测,并结合火场勘验资料综合分析,其死因鉴定和死亡方式推断结论方能准确。     

建立火场样品中汽油残留物ATD-GC-MS检验结果的评价方法

目的建立火场中汽油燃烧残留物ATD-GC-MS检验结果评价方法。方法将模拟燃烧样品用ATD-GC-MS法检验,检验结果通过对芳烃、烷烃、茚满、和萘系列的4个特征离子色谱图与已知汽油作比较,并利用向量夹角法计算样品与汽油色谱指纹图的相似度来对检验结果作评价。结果有汽油作助燃剂的模拟燃烧样品与汽油色谱指纹图的相似度一般大于90%,无汽油作助燃剂的样品则在60%以下。结论利用样品的4个特征离子色谱图与已知汽油作比较,并结合样品与汽油色谱指纹图相似度的计算,能对检验结果作出客观、可靠和准确的评价。     

Extraction of alternative fuels from fire debris samples*

Alternative fuels, specifically biodiesel, biodiesel blends, and E85 fuel, have been gaining a market share over the past few years. With the emergence of these fuels, fire debris analysts should be able to recognize their characteristics since these fuels may be encountered in casework. In this study, pure biodiesel (B100) and a 20% blend of pure biodiesel with petroleum diesel (B20) are examined as liquids and are extracted from debris samples using both passive headspace concentration and solvent extraction. Typical fire debris instrumental conditions are used to analyze these samples. Components of B100 and B20 may be observed in debris samples extracted using the passive headspace concentration method, but the chromatographic patterns are different from the pure liquid samples. When solvent extraction is used as a secondary extraction method on debris samples, the resulting patterns are consistent with the pure liquids of B100 and B20. E85 fuel, a blend of 85% ethanol and 15% gasoline, can be extracted using a typical fire debris extraction technique but requires slight modifications to typical fire debris instrumental conditions. E85 is shown at various stages of evaporation to demonstrate the resiliency of the ethanol. Additionally, samples of E85 were placed on carpet, burned and extinguished to demonstrate the effects of the suppression medium on the retention of ethanol.     

A New Method for the Characterization of the Degree of Fire Damage to Gypsum Wallboard for Use in Fire Investigations

A new method to characterize the degree of fire damage to gypsum wallboard is introduced, implemented, and tested to determine the efficacy of its application among novices. The method was evaluated by comparing degree of fire damage assessments of novices with and without the method. Thirty-nine “novice” raters assessed damage to a gypsum wallboard surface, completing 66 ratings, first without the method, and then again using the method. The inter-rater reliability was evaluated for ratings of damage without and with the method. For novice fire investigators rating degree of damage without the aid of the method, ICC(1,2) = 0.277 with 95% CI (0.211, 0.365), and with the method, ICC(2,1) = 0.593 with 95% CI (0.509, 0.684). Results indicate that the raters were more reliable in their analysis of the degree of fire damage when using the method, which support the use of standardized processes to decrease the variability in data collection and interpretation.     

The effect of compressed air foam on the detection of hydrocarbon fuels in fire debris samples

In 1998/99 the New Zealand Fire Service implemented compressed air foam delivery systems for the suppression of fires in rural areas. This study investigated whether the introduction of the foam to the seat of the fire created any problems in subsequent analyses of fire debris samples. No significant interferences from the foam were found when the samples were analysed by direct headspace using activated carbon strips. The only foam component detected was limonene.     

ATD—GC—MS法测定火场样品中痕量汽油燃烧残留物

目的为火场样品中痕量汽油残留物的检测建立一种简便、高灵敏度的检验方法和可靠的检验结果评判方法。方法用TenaxTA吸附管吸附富集火场样品中的汽油成分,然后用ATD—GC—MS法自动解吸和检测。通过模拟燃烧实验,探讨了检验结果的评判方法：根据样品的m／z（57＋85）、m/z（91＋105＋119）、m／z（117＋131）和m/z（128＋142＋156）四个质量色谱图与已知汽油作比较来对检验结果作评判。结果6组模拟燃烧实验中凡有汽油作助燃剂的样品．均检出汽油残留物成分。结论所建立的方法具有操作简便,检测灵敏度高,杂质干扰少,定性结论准确可靠等特点。可用于实际火场样品中痕量汽油残留物的检测。     

Sustained Combustion of Bodies: Some Observations*

Abstract: Previous tests have explored the fire effects and fuel characteristics of animal carcasses in intense fires of relatively short duration. Here, test fires were conducted involving intact human cadavers and torsos that included nonaccelerated, long‐duration fires involving the bedding and clothing (in the manner of typical accidental deaths). The objective was to observe the fire conditions (size, radiant heat flux, and duration), where a human body represented the major fuel package in a nonaccelerated fire. The pattern of damage to the body was documented and compared with that resulting from a furnished room fire. Two intact, unembalmed human cadavers were exposed to fires of simulated accidental origin. The bedding was ignited by an open flame, and the fires were allowed to burn unaided to self‐extinguishment. It was found that normal human bodies can support a modest‐sized fire for some 6–7 h under these conditions. The presence of a substrate material that can act as a wick for the combustion of the rendered body fat results in extensive destruction of the torso where the greatest amount of subcutaneous fat resides, with less damage to the head and limbs. A third (partial) cadaver was exposed to a recreation of a typical accidental fire in a furnished room that progressed to full room involvement. This fire of some 15 min of total duration inflected only surface‐layer damage to the torso of the victim.     

火场样品中汽油与稀释剂燃烧残留物的区分方法探讨

目的探讨火场样品中汽油与稀释剂燃烧残留物的区分方法。方法样品用ATD—GC—MS法检验,检验结果通过对芳烃、烷烃、茚满、和萘系列的4个特征离子色谱图与已知汽油和稀释剂作比较,并结合向量夹角法计算样品与汽油色谱指纹图的相似度来区分汽油与稀释剂残留物。结果个别品种的稀释剂燃烧残留物与汽油很相似,但彼此有某些差别。结论使用本方法,一般能将汽油与稀释剂燃烧残留物区分开。     

Homicide by fire

A study of homicide perpetrated by fire was performed on the case files of the Office of the Medical Examiner of Metropolitan Dade County in Miami, Florida, during the years from 1977 until 1984. A total of 26 cases were collected and analyzed as to age, race, sex, and the cause of death of the victim along with the blood alcohol content, the drugs detected at autopsy, and the blood carboxyhemoglobin level. Additionally noted were the geographic location of the terminal incident, the scene circumstances, how the fire started, who started the fire, and the reason for the fire. The most common victim was a 31-50-year-old white man who died from smoke inhalation while sober. Commonly, drugs detected were negative, and the carboxyhemoglobin levels were elevated. The fire occurred at "home" while the victim was sleeping. Usually, a flammable liquid was poured and ignited by a drifter who was a brief acquaintance and earlier involved in an argument with the victim.     

Unusual findings in a death caused by a car fire

Witnesses detected a burning car in the parking lot next to a discotheque in the early morning hours. After the fire had been extinguished, the charred body of the 23-year-old car owner was found in the driver's seat. The young man had been a guest of the discotheque the previous night and consumed plenty of alcoholic drinks. The traces left by the fire on the car suggested that the fire had started in the passenger compartment. At autopsy, greyish-brown discoloration and induration of the mucosa of the respiratory tract were found in addition to massive aspiration of soot and signs of soot swallowing. The macroscopic and histological findings pointed to a chemical burn of the airways probably caused by chlorine gases developing when the covering of the passenger compartment was burning. Chemical burns due to inhalation, aspiration and swallowing of soot are all signs of vitality, so that a smoldering fire must have gone on for a while inside the car with the windows closed. The most probable cause of the fire is that clothing or textile material in the car was set on fire by a burning cigarette.