• Journal of the Korean Institute of Gas
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• v.18 no.5
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• pp.20-25
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• 2014

Explosion characteristics of micro-sized aluminum dusts had been studied by many researchers, but the research of nano-sized aluminum dusts were very insufficient. In this study, an experimental investigation was carried out on the influences of nano and micro-sized aluminum dusts (70 nm, 100 nm, $6{\mu}m$, $15{\mu}m$) on dust explosion properties of aluminum particles by using 20 L explosion apparatus. With decreasing of particle size in suspended aluminum dusts, the LEC (lower explosion concentration) of nano-sized aluminum is lower than that of micro-sized aluminum. The particle size change of nano-sized aluminum dusts seems no obvious explosion differences than that of micro-sized aluminum dusts. From the observation of nano-sized aluminum particles by TEM (Transmission Electron Microscopy), it is estimated that increase of particles aggregation may have effects on the explosion characteristics of aluminum nanopowders.

• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.68-75
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• 2014

It is very important to classify explosion hazardous area (EHA) suitably and to use proper explosion-proof electric installations for facilities using flammable gases and liquids. In the past, various examples in the Notification of Ministry of Employment and Labor were referred to in classifying EHA. But, at present, many companies use the hypothetical volume in Korean Standards (KS). This study reviews the validity of EHA classification based on the hypothetical volume by comparing the calculated radii of EHA with those obtained by a consequence analysis program called PHAST and a mathematical approach in British Standards (BS). The radii of EHA by the hypothetical volume were found to be slightly larger than those by the other two methods. This was attributed to rather conservative uses of a safety factor(k) and a correction factor(f) for availability of ventilation in calculating the hypothetical volume. Since the differences are not so conspicuous, however, it is concluded that the hypothetical volume in KS is a valid means for the classification of EHA. This study also presents a table of the radii of EHA for easy reference by small-scale companies using city gas, C3-LPG and flammable liquid(toluene), respectively. The table consists of 25 leakage scenarios corresponding to combinations of 5 pipe(nozzle) sizes and 5 operating conditions for each flammable gas and liquid.

• Journal of the Korean Society of Safety
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• v.38 no.6
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• pp.9-15
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• 2023

Hydrogen is gaining attention as a sustainable and renewable energy source, potentially replacing fossil fuels. Its high diffusivity, wide flammable range, and low ignition energy make it prone to ignition even with minimal friction, potentially leading to fire and explosion risks. Workplaces manage ignition risks by classifying areas with explosive atmospheres. However, the effective installation of a blast wall can significantly limit the spread of hydrogen, thereby enhancing workplace safety. To optimize the wall installation of this barrier, we employed the response surface methodology (RSM), considering variables such as wall distance, height, and width. We performed 17 simulations using the Box-Behnken design, conducted using FLACS software. This process yielded two objective functions: explosion likelihood near the barrier and explosion overpressure affecting the blast wall. We successfully achieved the optimal solution using multi-objective optimization for these two functions. We validated the optimal solution through verification simulations to ensure reliability, maintaining a margin of error of 5%. We anticipated that this method would efficiently determine the most effective installation of a blast wall while enhancing workplace safety.

• Journal of the Korean Institute of Gas
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• v.26 no.5
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• pp.58-65
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• 2022

Gas explosion accidents could cause a catastrophe. we need specialized and systematic accident investigation techniques to shed light on the cause and prevent similar accidents. In this study, we had performed LPG explosion simulation using AUTODYN which is the commercial explosion program and predicted the damage characteristics of the structures by LNG explosive power. In the first step, we could get LPG's physical and chemical explosion properties by calculation using TNT equivalency method. And then, by applying TNT equivalency value about the explosion limit concentration of LPG on the 2D-AUTODYN simulation, we could get the explosion pressure wave profiles (explosion pressure, explosion velocity, etc.). In the last step, we performed LPG explosion simulation by applying to the explosion pressure wave profiles as the input data on the 3D-AUTODYN simulation. As a result, we had performed analyzing of the explosion characteristics of LPG in accordance with concentration through the 3D-AUTODYN simulation in terms of the explosion pressure behavior and structure destruction and damage behavior. The analyses showed that the generated stresses of the structures were lower than the compressive strengths in cases 1(two lane) and 2(four lane), while the generated stress in case 3(six lane) was 8.68e3 kPa, which exceeded the compressive strength of 5.89e3 kPa.

• Journal of the Korean Institute of Gas
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• v.9 no.3 s.28
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• pp.9-14
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• 2005

To estimate the explosion characteristics of converted gas, the study was examined into effects of altering oxygen concentration and adding hydrogen. From the result of the experiment, as the concentration of converted gas and hydrogen were increased at $21\%$ oxygen concentration, the lower explosion limit was low. Minimum explosion oxygen concentration was $6\%$. Maximum explosion pressure of converted gas was $4.61 kg_f/cm^2$, now Maximum explosion pressure rising velocity was $130.75 kg_f/cm^2/s$ at converted gas concentration $40\%$. Also, minimum ignition energy was 0.13 mJ at converted gas concentration $50\%$.

• Journal of the Korean Institute of Gas
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• v.10 no.2 s.31
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• pp.33-39
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• 2006

For the safety design and operation of many gas process, it is necessary to know certain explosion limit, flash point, auto ignition temperature and minimum oxygen concentration of handling substances. Also it is necessary to know explosion limit at high temperature and pressure. For the safe handling of propane, explosion limit and autoignition temperature of combustion characteristics for propane were investigated. By using the literatures data, the lower and upper explosion limits of propane recommended 2.0 vol% and 10.0 vol%, respectively. Also autoignition temperatures of propane with ignition sources recommended $450^{\circ}C$ at the electrically heated cruicible fumace(the whole surface heating) and recommended about $960^{\circ}C$ at the local hot surface. The new equations for predicting the temperature and the pressure dependence of the explosion limits of propane are proposed. The values calculated by the proposed equations were a good agreement with the literature data.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.367-373
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• 2016

Many of plastic powders handled in industry are combustible and have the hazard of dust fire and explosion accidents. However poor information about the safe handling has been presented in the production works. The aim of this research is investigated experimentally on explosive characteristics of various plastic powders used in industry and to provide additional data with safety informations. The explosibility parameters investigated using standard dust explosibility test equipment of Siwek 20-L explosion chamber. As the results, the dust explosion index ($K_{st}$) of ABS ($209.8{\mu}m$), PE ($81.8{\mu}m$), PBT ($21.3{\mu}m$), MBS ($26.7{\mu}m$) and PMMA ($14.3{\mu}m$) are 62.4, 59.4, 70.3, 303 and 203.6[$bar{\cdot}m/s$], respectively. And flame propagation velocity during plastic dust explosions for prediction of explosive damage was estimated using a flame propagation model based on the time to peak pressure and flame arrival time in dust explosion pressure assuming the constant burning velocity.

• Fire Science and Engineering
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• v.26 no.4
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• pp.63-69
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• 2012

Explosion limit is one of the major combustion properties used to determine the fire and explosion hazards of the flammable substances. In this study, the lower explosion limit (LEL) and upper explosion limit (UEL) of organic halogenated hydrocarbons were predicted by using the heat of combustion and chemical stoichiometric coefficients. The calculated explosion limits by the proposed equations agreed with literature data within a few percent. From the given results, using the proposed methodology, it is possible to predict the explosion limits of the other organic halogenated hydrocarbons.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.40-47
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• 2017

Dust explosion hazards are always present when combustible dusts are manufactured or handled in the process. However, industries is experiencing difficulty in establishing chemical accident prevention measures because of insufficiency of information on dust explosion characteristics of combustible dust handled in industry. In this study, we investigated experimentally dust explosion characteristics of two kinds of multi-walled carbon nano tubes (MWCNT) different in particle size distribution and examined classification of dust explosion hazardous area for MWCNT manufacturing or handling process by applying the NFPA 499 code. As a result, $P_{max}$, $K_{st}$, LEL, MIE and MIT of MWCNT 1 having $124.2{\mu}m$ median diameter are obtained 6.3 bar, $56bar{\cdot}m/s$, $125g/m^3$, over 1000 mJ, and over $650^{\circ}C$. $P_{max}$, $K_{st}$, LEL, MIE and MIT of MWCNT 2 having $293.5{\mu}m$ median diameter are 6.2 bar, $42bar{\cdot}m/s$, $100g/m^3$, over 1000 mJ, and over $650^{\circ}C$, respectively. MWCNT 1, 2 are not categorized as combustible dust listed in the NFPA 499 Code for classification of dust explosion hazardous area because explosion severity and ignition sensitivity of MWCNT 1, 2 are below 0.35 and 0.01, respectively.

• Journal of the Korean Society of Safety
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• v.33 no.3
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• pp.39-45
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• 2018

The occupational safety and health act defines how to evaluate the explosion hazardous areas according to KS (Korean Industrial Standards). Current KS have to follow IEC (International Electrotechnical Commission) 60079-10-1 1st edition and there has been no change since 2008. And its 2nd edition has been revised in 2015. In this study, IEC 1st Ed. (IEC 60079-10-1 1st edition) is compared with IEC 2nd edition. Total 112 case studies including four materials (methane, propane, benzene, methanol) are selected to test and explosion hazardous ranges evaluated by IEC 1st and 2nd Ed. are analyzed according to various leakage pressures and hole sizes. In order to verify the results calculated by them, PHAST, which is one of the most representative consequence analysis programs, is employed. As a result, it can be concluded that there are many differences between IEC 1st and 2nd Ed. due to the discharge and the ventilation parameters. As comparing with PHAST, it is confirmed that IEC 1st provides more conservative values than PHAST. Even if IEC 2nd Ed. provides more conservative for gases, this fails to provide more conservative values for liquids. Therefore, it is worth to note that a large value between the explosion hazardous ranges value calculated by the IEC 1st Ed. and 2nd Ed. should be selected until further investigation and analysis is made. Morevover, the full consideration for IEC 2nd Ed. have to be needed.