Earticle

It is widely known that a fire was caused by an electrical cause of the compressor-driven relay installed in the kimchi refrigerator manufactured before september 2005. However, there is no case of concretely demonstrating the mechanism of fire in the relay. Accordingly, this study analyzed the fire case of a kimchi refrigerator and confirmed the cause of the relay’s ignition through a fire reproduction experiment. First of all, PCBs were collected for each year of W company’s products where fires frequently occur, and the structural differences of relays were compared using X-rays. Afterwards, it was confirmed that the relay was fired due to structural causes by the repeat opening/closing test on the relay. In addition, from the actual fire test, it was proved that if ignited in the relay, the fire could spread to the entire kimchi refrigerator. Finally, based on the research results, a fire investigation technique for kimchi refrigerator were presented

Electric heaters with PTC thermistor heater elements have been widely used for heating at home and businesses, replacing heating devices using fossil fuels. The PTC thermistor heater device maintains a constant temperature by controlling a heating value by increasing or decreasing the current as the resistance value changes to limit the amount of current. In this paper, since a fire occurs due to indiscreet use of the device, careless use of the PTC thermistor heater device-type electric heater and the defect state of the device itself were presented. After that, the heating characteristics and the possibility of firing were analyzed through lots of experiments. As the separation distance from the combustible material approached, the temperature of the combustibles material increased proportionally. However, the temperature of the PTC thermistor heater element itself was kept constant. In addition, even if serious overheating conditions were set, the temperature overheating prevention device of the device itself was operated, which did not lead to abnormal overheating and firing of the heater device itself. It could be verified through empirical experiments that the firing could be caused by arc generation between PTC heater device and adjacent electrode, as an abnormal current occurs under conditions where the resistance of thermistor itself is interfered with by the inflow of external conductive materials. In conclusion, based on the results of the reproduction test, matters to be considered when improving the fire investigation and fire prevention system were presented.

LIB-related fires are continuously increasing due to the increase in personal transportation means and the commercialization of electric vehicles. Among the LIB components, the separation membrane is the most important key material for stability, and there is a problem in that it is lost at the scene of a fire and cannot confirm its shape. Accordingly, fire statistics and cases were analyzed, and the experimental outline was established through theoretical consideration of the wet separation membrane, which is the most used as a personal transportation means. As for the experimental method, we conducted a study on the shrinkage rate and tensile strength of the wet separator according to thermal damage for each temperature change with five experimental variables using the wet separator, which plays an important role in the stability of the battery components, as a sample. Through this, the change in shrinkage rate and mechanical properties of the wet separator were derived to understand the fire of lithium-ion batteries caused by damage to the wet separator and to contribute to the fire investigation analysis technique.

In a recent refrigerator fire, there is a case where it was concluded that the fire was caused by other reasons, such as overcurrent, as a result of analyzing evidence that could be attributed to a relay abnormality. control unit during fire investigation, various devices are connected to the load side and the arc generated when the relay is operated repeatedly is eliminated. It was designed and tested as an experiment to check the possibility of fire that can occur by deforming the contact point. As a result of the experiment, it was observed that severe melting and damage were seen at the contact point, and that it was difficult to distinguish the boundary between Ag and Cu. As a result of X-ray confirmation, distortion and flattening of the contact point were observed. As a result of EDS analysis, most of the sample contacts contained Ag, but in the case of the relay contacts connected to the load, Ag decreased and O, Cu, and Sn increased. As a result, the higher the frequency of use of the relay, the higher the temperature and resistance due to the arc inside, and the change of the shape, surface, and composition of the contact could lead to ignition. It is suggested that appropriate countermeasures against relay fires such as method guidance are necessary.

Recently, as natural interiors have been in the spotlight, there is a trend to produce and assemble interior accessories using wood or bark. For small items made in this way, an oil finishing material for wood must be used, and the most used currently is oil stain. Linseed oil, which is classified as a drying oil among vegetable oils, is used as the main ingredient in oil stain. Linseed oil, which is a drying oil, consists of unsaturated fatty acids, and many of them are composed of polyunsaturated fatty acids, so it oxidizes very quickly in the air. Because of these properties, there is a risk of spontaneous ignition due to oxidative heat in the process of improperly processing the painting tools generated after wood painting. Therefore, this study analyzes fire cases that occurred at the fire site, and based on this, deduces the possibility of spontaneous ignition due to oxidative heat in painting tools with oil stains through a re-enactment experiment, and suggests considerations for fire detection and fire prevention measures.

In industrial sites that discharge pollutants into the atmosphere, dust collection facilities are generally installed to prevent environmental pollution. Although the dust collection equipment greatly contributes to the prevention of environmental pollution, the painted sludge adhering to the inside of the duct leading to the dust collector is very vulnerable to fire. It is a device that collects polluting gases generated in the work process, and is connected to the duct, and has a structure in which sludge is inevitably stuck in the process of collecting the polluting gas inside the duct. It acts as a combustible material among the three elements of combustion conditions, and when an ignition source acts due to the working environment, it causes explosive combustion and has a structural environment in which combustion can only proceed to the dust collector connected to the outside. In this study, it can be seen that the coating sludge has sufficient energy as a combustible material through the physical property analysis and fire reproduction test, and that the sparks generated from the duct repair tools and cleaning tools are sufficient as an ignition source. Therefore, based on the results of this study, I would like to suggest methods for the removal of combustibles (painting sludge) and the removal of ignition sources (work tool spark) among the three elements of combustion to prevent fires inside industrial dust collector ducts in advance.

In general, crop protection agents are of great interest in research and development to increase productivity by protecting crops from various pests. However, if a safety accident occurs during the manufacturing process of crop protection agents, serious environmental pollution can occur, and several fires and safety accidents related to crop protection agents have occurred in Korea. However, it was not effective in preventing fire as it was simply treated as spontaneous ignition or carelessness without a clear cause. Therefore, through this thesis, the probability of fire was studied by sharing and analyzing two cases of fires related to crop protection agent manufacturing sites in Ulsan. The main outcome of the study was to confirm the ignition potential and risk of CCTA, and suggested improvement plans during storage and a starting point for fire detection to prove the ignition probability of chemical safety accidents. And it was evaluated again that the example of the crop protection plant presented as a fire case in Ulsan in 2020 and 2021 cannot be classified as a fire.

The types of frying oil we use are divided into dry oil, semi-drying oil and non-drying oil according to the iodine value, and the higher the iodine value, the greater the degree of unsaturation and the greater the reactivity. In this study, the characteristics of spontaneous ignition of oil residues fried in oil with different iodine values were identified, and the iodine value and the flash point after rancidity were identified. As a result, it was confirmed that the higher the iodine value, the faster spontaneous ignition. The iodine value was similar before and after parity. In addition, the flash point and the ignition point decreased as the iodine value increased and the heating time increased. This is thought to be due to the difference in free fatty acids. Therefore, it is an important factor in determining the possibility of spontaneous ignition to confirm which oil was used by the fire investigator. In addition, in order to prevent such spontaneous ignition, it is necessary to cool it with a large amount of water when throwing away frying residue, and it is important to recognize that a fire may occur due to oil residue.