• Fire Science and Engineering
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• v.16 no.2
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• pp.59-69
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• 2002

The conventional fire extinguishing gas-agent system has a configuration in which the gas-agent comes out of a cylindrical container having vertically settled shape. However, in this study a horizontally installed container of a piping shape having a cylinder of the same shape with a cylinder valve and a discharge nozzle was used, and the relationship between orifice size of nozzle and discharge rate of gas-agent was investigated through various experiments including the measurement of discharge rate under different ambient-temperature conditions. In such experiments, HCFC Blend A was used without super-pressurization by nitrogen. From this research, it was observed that statutory discharge duration of 10 seconds can be met if the relatively large size of the valve and the nozzle orifice were properly selected.

• Journal of the Korean Society of Safety
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• v.27 no.1
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• pp.20-25
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• 2012

The purpose of the study is to assess the extinguishing concentration of inert gases in engine nacelle fire. The experiment was performed with a two dimensional rectangular bluff body stabilized flames, where the fuel was ejected to counter flow and co-flow against an oxidizer stream. Two inert gases, $CO_2$ and $N_2$, were used for extinguishing agent in the oxidizer and methane was used for fuel. The main experimental parameters were the direction of injecting fuel, the kinds of agent and the velocity ratio between air and fuel streams, which controlled the mixing characteristic near bluff body and the strength of recirculation zone in the downstream. The result shows the flame structure and the mode were strongly dependent with fuel/air ratio and the fuel jet direction. For both flow configurations, the extinguishing concentration of $CO_2$ was smaller than the $N_2$ because of the large heat capacity of $CO_2$. However, the concentration of inert gasesat blowout was much smaller than those in the cup burner and coflow jet diffusion flames, which implies that the extinction mechanism of bluff body stabilized flames was mainly due to the aerodynamic aspect. Compared to co-flow fuel injection, the extinguishing concentration of inert gases under counter flow configuration was lower. The effect of direction might result from the mixing characteristic and strength of recirculation zonearound a bluff body. More details should be investigated for the characteristic of recirculation zone in the wake of bluff body using the LES(Large Eddy Simulation).

• Fire Science and Engineering
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• v.30 no.4
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• pp.103-110
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• 2016

While the demand for the gas system fire extinguishers increases every year, there are insufficient safety measures for assessing the extinguishing performance, such as system safety and reliability in the preparation of increasing demand, which has emerged as a social problem. One of the most critical causes of accidents occurring with the gas extinguishing system is pressure leakage from the extinguishing agent storage container. This is considered to be one of the critical factors on which the success of fire suppression depends. In this study, its safety measure was studied, Because it was deemed urgently necessary. The newly developed pressure leakage monitoring system is a system monitoring storage condition, pressure, leakage and discharge of the storage container related to agent concentration, which is one of the critical factors for fire suppression. This was developed to be applicable to the $CO_2$ and HFC-23 systems. Therefore, for structural safety analysis, the safety performance was verified by the fluid structure coupling analysis of the safety problems that may occur when the pressure leakage monitoring system is applied to the gas fire extinguisher. For analysis programs, the FloEFD program from Mentor Graphics was used for computational fluid dynamics analysis and ABAQUS from Dassault Systems was used for structural analysis. From the result of numerical analysis, the structure of $CO_2$ did not develop plastic deformation and its safety was verified. However, plastic deformation and deviation issue occurred with the HFC-23 monitoring system and therefore verified the structural safety of pressure leakage monitoring system by data obtained from redesigning and adjusting the condition of numerical interpretation three times.

• International Journal of Safety
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• v.4 no.2
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• pp.24-29
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• 2005

An experimental study was presented for extinguishing characteristics of liquid fuel fire by water mist($Dv_{0.99}{\leq}200{\mu}m$) containing potassium acetate and sodium acetate trihydrate. To evaluate the extinguishing performance of water mist containing additives, the evaporation characteristics of a water droplet on a heated surface was examined. The evaporation process was recorded by a charge-coupled-device camera. Also, small-scale extinguishing tests were conducted for n-heptane pool fire in ventilated space. During the experiments, flame temperatures were measured, and concentrations of oxygen and carbon monoxide were analyzed by a combustion gas analyzer. The average evaporation rate of water droplet containing additives was lower than that of pure water at a given surface temperature and decreased with the concentration increase due to the precipitation of salt in the liquid-film and change of surface tension. In case of using additives, the fire extinguishing times was shorter than that of pure water at a given discharge pressure and it was because the momentum of a water droplet containing additives was increased. And also dissociated metal atoms, potassium or sodium, were reacted as a scavenger of the major radical species OH, H which were generated for combustion process. Moreover, at a high pressure of 4 MPa, the fire was extinguished through blowing effect as well as primary extinguishing mechanisms.

• Journal of Korean Society of Disaster and Security
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• v.10 no.2
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• pp.35-41
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• 2017

Recently chemical intoxication related with the use of chemical extinguishing agents occurs frequently. With the industrialization, high-rising of building and increase of fire risk, we use the various extinguishing agents and the safe use become important. In this study I carried out the risk assessment of representative chemical extinguishing agents (HCFC-123, HFC-125) using the CHARM and got the meaningful qualitative outcome. This study is significant in that the risk assessment of chemicals was conducted using CHARM, chemical risk assessment tool. It is expected that the results will be utilized as the basic data for the national chemical safety management.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1997.11a
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• pp.598-605
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• 1997

In recent years, the number of vehicle fires, as well as the number of motor vehicles, has been increasing rapidly. Therefore, several types of automatic fire suppression systems for the engine compartment of automobiles have been developed to extinguish automobile fires, and most of these systems use halon 1301 as a fire extinguishing agent. Due to environmental concerns, the phase-out of halons has been announced, so now there is a need to replace halon 1301. For this, a 1,1,1,2,3,3,3-heptaflouropropane (HFC-227ea, FM-$200^{TM}$) gas-filled Aqueous Film- Forming foam (known as AFFF) extinguisher was devised even though air foam extinguishers could be used. This is because the air in the foam bubbles is a source of oxygen required for the combustion reaction. It can be surmised that it is possible to increase the fire extinguishing efficiency of AFFF by filling in foam bubbles with a gaseous extinguishing agent. The best choice is the FM-$200^{TM}$ gas-filled AFFF, Which has the maximum expansion ratio of 62:1. This makes it possible for the expanded foam to rapidly fill the engine compartment.

• Journal of the Korea Safety Management & Science
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• v.24 no.4
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• pp.117-124
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• 2022

This study collected powder extinguishers with 6-10 years of elapsed life from January 2012 to January 2017 in market, factory, and apartment areas to experiment with changes in fineness and to examine the characteristics of extinguishing power. First, in the case of ABC powder, 98.3 wt% of the 8-year market area and 98.6 wt% of the 10-year apartment complex were found to be inappropriate in the first, second, and third arithmetic average analysis of the powder extinguisher from 6 to 10 years. That is, the fine distribution and size of the powder extinguishing agent particles should be managed within an appropriate range. It is analyzed that the powder fire extinguisher may experience a change in the fineness of the powder depending on the external environment exposure, placement, management status, and age of use, resulting in a decrease in digestive power or inability to radiate. Second, the fire extinguisher cannot be used in the initial fire suppression depending on the place of deployment, the environment of deployment, the progress of the number of years of use, and maintenance, so it is necessary to strengthen the device that enables fire extinguisher maintenance and inspection. Third, in the manufacturing process, the charging method should also be reviewed in consideration of the conditions of the workplace, the humid season, and the rainy environment.

• Fire Science and Engineering
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• v.33 no.3
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• pp.51-55
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• 2019

To prevent ozone depletion caused by CFCs, the replacement of Halon with clean agents has been developed in the fire protection field along with refrigerants, detergents, and foaming agents. The alternatives for Halon 1211 have been developed in the portable fire extinguisher area and HCFC-123 is used widely as a clean fire extinguishing agent. The type of expellant gas is important because their own vapor pressure is low. In this study, HCFC-123, HCFC-124, HFC-125, and Novec-1230 were selected as fire extinguishing agents and CO₂, which is expected to improve the fire extinguishing ability, was chosen as the expellant gas. For each agent, experiments changing the agent and CO₂ amount were carried out and HCFC-123 showed a good result, as expected. The extinguisher, HCFC-123 of 1.5 kg, showed the same ability to suppress a class A and B fire as the extinguisher, HCFC-123 of 2.5 kg, which is currently sold on the market. According to this result, the expellant gas has a subsidiary fire extinguish effect. This can reduce the amount of HCFC fire extinguishing agent, which is categorized in the phase-out alternatives, and is a more eco-friendly and economical fire extinguisher than the previous one. This study can also help solve the problems of CO₂ fire extinguishers for class B and C fires, and can be used to extinguish electric and electron facilities fire, which contains large amounts of class A fire combustibles.

• Fire Science and Engineering
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• v.28 no.3
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• pp.1-9
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• 2014

In this study, it was developed to the design program optimization the design factors of the carbon dioxide fire extinguishing system on the basis of design theory for the carbon dioxide fire extinguishing system, national emergency management agency (NEMA) notice No. 2012-11, KS B 6261 and steepest descent method of optimization. The design program was developed to C++ compiler based on established the logic and algorithms and was to operate on the Windows operating system. The optimization of design factors for the carbon dioxide fire extinguishing system are minimized subject to constraint on agent flow rate, emission time and design variables (pipe size etc.). It was verified to the design program performance for test system, and it was provided to the foundation for optimal design in fire fighting field. Also, it is considered to improve the efficiency of the fire extinguishing system and to maximize of fire suppression as the construction of the carbon dioxide extinguishing system based on the optimal design factors.

• Journal of Integrative Natural Science
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• v.6 no.3
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• pp.151-157
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• 2013

The ion exchange resins were synthesized from 1-aza-18-crown-6 macrocyclic ligand attached to styrene (2th petroleum in 4th class hazardous material) divinylbenzene (DVB) copolymer with crosslinks of 1%, 6%, and 15% by substitution reaction. These synthetic resins were confirmed by chlorine content, elementary analysis, surface area, and IR-spectrum. The object of this study was to seperate the metal ion absorbed in reinforcement water fire extinguishing agent. As the results of the effects of pH, equilibrium arrival time, and crosslink of synthetic resin on metal ion adsorption for resin adsorbent, the metal ions were showed high adsorption at pH 3 or over and adsorption equilibrium of metal ions was about 2 hours. In addition, adsorption selectivity for the resin in water was the order of Al (III) > Ni (II) > Sm (III) ions, adsorbability of the metal ions was in the crosslinks order of 1%, 6%, and 15%.