• Journal of the Korea Safety Management & Science
• /
• v.19 no.2
• /
• pp.31-39
• /
• 2017

Classify of explosion hazardous areas must be made at the site where flammable materials are used. This reason is that it is necessary to manage ignition sources in of explosion hazardous areas in order to reduce the risk of explosion. If such an explosion hazard area is widened, it becomes difficult to increase the number of ignition sources to be managed. The method using the virtual volume currently used is much wider than the result using CFD(Computational Fluid Dynamics). Therefore, we tried to improve the current method to compare with the new method using leakage characteristics. The result is a realistic explosion hazard if the light gas is calibrated to the mass and the heavy gas is calibrated to the lower explosion limit. However, it is considered that the safety factors should be taken into account in the calculated correction formula because such a problem should be considered as a buffer for safety.

• Journal of the Korean Society of Safety
• /
• v.22 no.1 s.79
• /
• pp.36-39
• /
• 2007

It is important to know Minimum Ignition Energy(MIE) of flammable materials for ignition hazard of chemical processes etc.. Currently a capacitor discharge is used mainly to measure the MIE. Then, it is impossible to control actively discharge energies and discharge time because the MIE measurement uses a high voltage capacitor and fixed capacitor. However, the control of discharge energy and discharge time will be convenient if self-sustain discharge is used. In this paper, we measured the MIE by self-sustain discharge of a pulse shape to propose the new measuring method of the MIE. AS a result, ignition energies are increased gradually as discharge duration time gets longer, and discharge current grows larger. Also, an arc discharge and a glow discharge occurred during the experimental period, and the ignition by glow discharges happened when discharge duration time was $90{\mu}s$, discharge current was 8A and 1A Especially, the MIE occurred the 0.05mm and 0.08mm of the gap distance between discharge electrode in the same discharge duration time.

• Journal of the Korean Institute of Gas
• /
• v.9 no.1 s.26
• /
• pp.9-15
• /
• 2005

Hydrogen is considered to be the most important future energy carrier in many applications reducing significantly greenhouse gas emissions, but the safety issues associated with hydrogen applications need to be investigated and fully understood to be applicable as the carrier. Therefore, there is a considerable demand for further research concerning the dispersion of hydrogen/air mixture clouds and the possible consequences of their ignition. In this study, the dispersion of hydrogen gas in atmosphere has been analysed with atmospheric condition by concerning the buoyancy of hydrogen. The hazard ranges to wind direction increase with wind speed and the stability of atmosphere. The concentration of hydrogen at just above ground is nearly zero due to buoyancy of hydrogen gas. Therefore, the ignition probability of hydrogen gas cloud is low and the hazard of explosion or fire associated with hydrogen gas is relatively low comparing with the other fuel gas such as propane or butane.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.9 no.3
• /
• pp.81-87
• /
• 2009

In this study, we have investigated the combustibility of five shrubs growing in Youngdong area such as Lindera obtusiloba, Lespedeza maximowiczii, Zanthoxylum piperitum, Zanthoxylum schinifolium, and Corylus heterophylla var. thunbergii using the ignition temperature tester, the cone calorimeter and the smoke density chamber in order to estimate the danger of a forest fire. The results showed that Lespedeza maximowiczii has the lowest ignition temperature, the fastest ignition time and the highest average release concentrations of CO and $CO_2$. Zanthoxylum piperitum and Zanthoxylum schinifolium showed the highest level in heat release and smoke release, respectively. Therefore, we have concluded that Lespedeza maximowiczii has the highest ignitibility, Zanthoxylum piperitum the most intensive fire spread and fire intensity, and Zanthoxylum schinifolium and Lespedeza maximowiczii most difficult to escape from a forest fire.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1913-1916
• /
• 1996

With a progress of electrical and electronic technology, radio-frequency circuits including high frequency components are widely applied to various industrial installations. Some of them are used in hazardous locations where explosive or flammable gases exist. As a result, ignition of such gases may be induced by a spark discharge when the radio frequency circuits are switched on or off. The purpose of this study is to investigate the ignition hazards of acetylene-air and ethylen-air mixtures experimentally based on the IEC 79-3 publication. In this experiment, we used a high frequency resistive circuit which consists of a co-axial cable, a $10{\Omega}$, $20{\Omega}$, $30{\Omega}$, $40{\Omega}$ or $50{\Omega}$ resistor and a power amplifier with frequency range up to almost 1 MHz. Experimental results show that the ignition of the acetylene-air and ethylen-air mixtures due to spark discharge depends primarily on the frequency of the power source in the resistive circuit: the minimum ignition voltage increases gradually with the increase of the frequency.

• Journal of the Korean Society of Safety
• /
• v.20 no.3 s.71
• /
• pp.78-83
• /
• 2005

In this study, the evaluate characteristics of fire and explosion of MEK-PO are subjected to spontaneous ignition, flash point and explosion hazard. The minimum ignition temperature and instantaneous ignition temperature for MEK-PO were $188.5^{\circ}C\;and\;230^{\circ}C\;at\;225{\mu}L$. In addition The flash point for MEK-PO was obtained at $49^{\circ}C$. Furthermore, the maximum explosion pressure and the maximum explosion pressure rising velocity: using MCPVT (mini cup pressure vessel tester) were $10.82kgf/cm^2\;and\;33.72kgf/cm^2{\cdot}s$.

• Proceedings of the KIEE Conference
• /
• 1998.07e
• /
• pp.1749-1751
• /
• 1998

Close to high power radio/radar transmitters there is a possibility that sparks may be occur at discontinuities in metallic structures. If these structures are in an area in which a flammable mixture may be present, there is a possibility that a fire or explosion may be caused by the sparking. A number of assessment procedures for quantification of the hazard have been produced. This paper reviews the bases of the British Standard covering ignition hazards by radio-frequency radiation and presents some ignition test apparatus to access these hazards.

• Journal of the Korean Society of Safety
• /
• v.33 no.2
• /
• pp.39-44
• /
• 2018

Dust explosions are occurring in a variety of industries. A dust explosion caused by a specific energy generates huge amount of energy in the ignition and releases decomposition gas. Damages can be increased since this released decomposition gas can cause second and subsequent explosions. In this study, the goal was to obtain practical information on what could affect the explosion by comparing the characteristics of two kinds of dusts with completely different chemical properties. Three kinds of dusts were measured and evaluated for explosion pressure, dust explosion index, explosion limit and minimum ignition energy. It is possible to grasp the characteristics of each dust and use it as useful accident prevention data in the production of raw material powder.

• International Journal of Safety
• /
• v.1 no.1
• /
• pp.47-51
• /
• 2002

This study was performed by measuring the minimum ignition temperature of polyurethane form recovered from the recycling process of the end-of-life home appliances. The critical ignition temperature of polyurethane form was lower as the size of the sample vessel was increased, and that of polyurethane form using cyclopentane as the forming agent was relatively lower than the polyurethane form using CFC and the combustion of cyclopentane-polyurethane form occurred fiercely. It is considered that the recycling process of end-of-life home appliances using cyclopentane-polyurethane form as the insulator would require a special fire and dust explosion prevention measures since there exists a high potential hazard of fire and dust explosion during crushing and storage processes.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.350-355
• /
• 2003

Flame onset and propagation within hydrogen premixed gas mixture are numerically investigated in an rectangular enclosure. A detailed chemistry for hydrogen reaction is applied to anticipate the thermochemical behavior of intermediate species appropriately. To facilitate computation, 10 species and 16 elementary reaction steps for hydrogen combustion are taken into account. On the basis of 30 % of hydrogen concentration in hydrogen-air mixture, the effects of position and quantity of ignition sources on the flame evolution are analyzed. From the simulation results, the means that can lessen the possible hazard caused by flame propagation are suggested.