Bulletin of Japan Association for Fire Science and Engineering
Online ISSN : 1883-5600
Print ISSN : 0546-0794
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Volume 61 , Issue 1
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Paper
  • Wataru HONDA, Eichi ITOIGAWA, Michitaka UMEMOTO
    Volume 61 (2011) Issue 1 Pages 1-10
    Released: June 16, 2011
    JOURNALS FREE ACCESS
    Many kinds of peculiar technology, skills or tacit knowings have been lost at the mass hiring and the mass retirement period in various industries in recent years. Fire fighting organization has also similar situation. Therefore, the risk that firemen get injured in firefighting would increase because of the reason above mentioned.
    In this paper, the authors applied FMEA, representative method of reliability analysis, for the safety management of fire fighting. First, the authors chose the extinguish activities of the embers by fireman as a research target because of understanding of high risk task through the analysis of the data base with fireman' s accident "syoubou-hiyarihatto-data-base". After constructing work process of the activities, the potential risk was evaluated. In addition, through questionnaire survey on fireman' s regarding safety management, the authors proposed some practical use plans of FMEA for safety activity.
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  • Akira YOSHIDA, Itaru SAKURAI, Hiroyoshi NAITO, Yoshinobu KOTANI
    Volume 61 (2011) Issue 1 Pages 11-19
    Released: June 16, 2011
    JOURNALS FREE ACCESS
    In the present study, effect of water mist on the stabilizing and extinction mechanisms of a jet diffusion flames developing in a coaxial-flow burner was investigated experimentally, using propane as fuel. Water mists were generated by a commercial ultrasonic humidifier (Toyotomi-TUH-A9). The characteristics of water mist were measured by a PDPA. The mist sizes were found to have nearly normal distribution and ranged from 1 to 44 μm. The arithmetic and the Sauter mean diameters are D10 ≒ 15 μm, D32 ≒ 21 μm, respectively. When water mist was added into air flow, the flame stability limits and the distributions of flame temperatures, soot concentrations, flame brightness were measured. As a result, it was shown that the flame stability limits and flame temperatures are reduced as the water mist flow rates are increased because of the extinguishment due to evaporation which causes the cooling and depletion of oxygen in the flame zone. Likewise, soot concentrations and the flame brightness decrease with the increase of the mist flow rates. Furthermore, it was shown that extinction of the attached flame was caused by increase of the heat transfer from flame to mist. On the other hand, it was found that the local extinction of turbulent flame was spread with the increase of the water mist flow rates. Also it was confirmed that the structure of the turbulent diffusion flame varied with the mist flow rates which flowed into in a turbulent flame.
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  • Akiko NATORI, Kazunori HARADA, Takao WAKAMATSU
    Volume 61 (2011) Issue 1 Pages 21-27
    Released: June 16, 2011
    JOURNALS FREE ACCESS
    In the standard verification method for fire resistance of Building Standards Law of Japan, it is verified that the principal building construction elements shall not collapse by foreseeable fire effect. In case of localized fire scenarios, 20 minutes of fire is assumed close to the elements in question. Using the prescribed input parameters and calculation formulas, the conformance is evaluated. However the resultant safety level is not clear to practice engineers and building owners. To reveal the safety level attained by the verification method, the variability and uncertainties of input parameters were quantified by probability density functions. Then, the probability of failure is calculated by the method of reliability engineering. The analysis was carried over a group of column specifications that exactly satisfy the verification method for localized fire scenario. It was found that the safety index of the group was as large as around eight. The five governing parameters were specified as fire duration, basic temperature rise rate and correction temperatures for residual strength ratio of steel material, for ultimate temperatures for overall and local buckling. For generalization, sensitivity analysis was carried out for the practical range of column length, diameter and plate thickness. As a result, linear correlation between safety index and partial safety factors were proposed for rational design for target safety described by safety index.
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