Since motor gasoline is a highly volatile liquid fuel, the gasoline vapor generated from the liquid surface mixes with air to form a flammable air-fuel mixture in the surroundings. For this reason, when gasoline is spilled on a floor for the purpose of arson, attention must be paid not only to the fire hazard of the gasoline spill on the floor, but also the fire hazard of gasoline vapor that has already evaporated and diffused. The foam extinguishing agent products prevent the evaporation of gasoline and ignition of gasoline by covering the liquid surface of the gasoline with foam, but are not effective for gasoline vapor in the gas phase. In this study, we proposed a method for spraying aqueous film forming foam extinguishing agent containing low-volatile oil (hybrid combustion inhibitor) to gasoline spill in order to remove gasoline vapor and make the flammable gas incombustible. First, the vapor pressure change was measured when low volatile oil was mixed with gasoline. Next, we conducted gasoline vapor absorption experiments using the hybrid combustion inhibitor. We modeled the gasoline vapor absorption behavior by the hybrid combustion inhibitor and derived the vapor absorption coefficient. Furthermore, we conducted combustion suppression experiments for gasoline spills using a hybrid combustion inhibitor, and examined the inflammable effect of the proposed hybrid combustion inhibitor. We confirmed that by spraying the hybrid combustion inhibitor, the gasoline vapor in gas phase was absorbed and the combustion of gasoline vapor was suppressed. It was found that the combustion suppression effect of the hybrid combustion inhibitor can be predicted by using the proposed vapor absorption model.

This study is about heating behavior of the soffit member by the opening fire plume ejection, and it is the condition that is placed H-beam under the tip of the soffit member. The large scale experimental apparatus was used, and the experimental conditions are the opening size, soffit member size, spandrel wall, handrail, and fire source. The result of this experiment, derived a non-dimensional model (10) of the ceiling jet model of the Alpert considering the opening fire plume ejection for the temperature of the lower part of the soffit member. In addition, as a result of deriving the correlation between q"_H.web and L_HF/L_f for incident heat flux of H-Beam by using the location of 500 °C from the lower surface of the soffit member, and the result was approximately the same as the result of the incident heat flux of the ceiling member in free space.

Recently, the efficiency of water spray systems in mitigating tunnel fires has been attracting a lot of studies. In this work, a CFD modeling is presented to numerically investigate the effects of a heavy goods vehicle (HGV) fire with the water spray system, point extraction ventilation system, and various vehicular blockages in a tunnel. A fire source due to an HGV with a peak of the heat release rate (HRR) of 100MW is simulated in this study. The vehicular blockage, which is defined as the ratio of the cross-sectional area of the blockage near the fire source, is simulated under three types: 9.8 %, 21.7 %, and 33.6 % blockage. Using numerical modeling, this study investigates the distributions of smoke spread, temperature, CO concentration, and visibility for different scenarios. Seven cases are analyzed in which the tenability conditions are influenced including vehicular blockage, water flow rate, and point extraction ventilation system. In this study, the temperature and visibility are the key factors for safe evacuation. In particular, the assessments of the tenability conditions using the indicators of Efectis Nederland BV to display different fire scenarios are presented and discussed.

Many researches on fire and firefighting activities focus on individual elements of those activities and study their characteristics in detail. On the other hand, reports of actual fires and firefighting activities are organized as fire statistics, which schematically show the entire process of fire and firefighting activities. Hence, by comprehensively analyzing the fire statistics, it is possible to systematically understand the relational structure of the entire process of fire and firefighting activities from fire to suppression in actual fires. In this study, by using multiple regression analysis and structural equation modeling for fire statistics, we clarify the relationship between each element of fire and fire extinguishing activities with respect to the time from the start of water discharge to the suppression. As a result, a latent element not recorded in the fire statistics is important the element of the relational structure, and it was estimated as fire force. The relationship between the number of pumps and fire extinguishing equipment is clarified as well.