• Journal of the Korean Society of Safety
• /
• v.29 no.4
• /
• pp.78-84
• /
• 2014

Viscosity agents were added to water to improve extinguishing performance of low pressure water mist suppression system on wood cribs fire, and a small scale wood cribs fire experiment was conducted to measure the extinguishing performance. CMC and agar were used for viscosity agent and as the amount of viscosity agent enlarges, it showed the increase of the viscosity of aqueous solution and the decrease of the fluidity. On wood cribs fire experiment, the extinguishing efficiency was improved with supplemental viscosity agent as it enhanced the adhesive time of aqueous solution on the wood, and therefore expanded the contact time of fire surface. The surface tension of aqueous solution was decreased with the addition of agar which to be assumed as an increase factor of extinguishing efficiency. By the extinguishing experimental result, the most effective extinguishing agent was CMC 0.6 wt.%, with the flame suppression time and the extinguishing time were reduced by 70s and 93s respectively at this concentration.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2008.11a
• /
• pp.76-79
• /
• 2008

In this work wood crib burning behaviors have been simulated by using the FDS(Fire Dynamic Simulator) program. Wood cribs are regularly stacked arrays of wood sticks, and available for the performance rating of fire-extinguishers. On the basis of an angle iron supporter 26 layers of wood sticks have been stacked up. Each layer consists of 5 or 6 wood sticks which are placed in parallel, with a constant distance, and in alternating rows. They are laid between the horizontally adjacent sticks at the before last layer. The wood crib is ignited instantaneously by an amount of burning gasoline below. A comprehensive simulation of such a practical sophisticated combustion is still too difficult to realize with any currently available computer, although the performance of modern processors is getting better everyday. We could carry it out here through parallel computing on the HPC(High Performance Computing) cluster as the feasible alternative. At last the validation has been executed by means of temperature distribution data measured by the thermal video camera.

• Fire Science and Engineering
• /
• v.31 no.6
• /
• pp.16-22
• /
• 2017

In Korea, performance-based fire safety designs are being discussed to deal with the various risks of fire in complex and diverse types of structure. However, performance-based fire safety designs are not actively employed because it is difficult to estimate the fire characteristics related to the various factors in buildings. In this study, real scale fire tests were conducted based on fire severity levels and fire loads provided in He New Zealand Building Code, in order to use the results as guidelines and fundamental data for performance-based designs. In the real scale fire tests conducted in a 10MW full-scale calorimeter, wood cribs were placed in a $2.4(L){\times}3.6(W){\times}2.4(H)m$ mock-up of a compartment which had one $0.8(L){\times}2.0(H)$ opening for different fire loads and heating was continued until all of the wood cribs were burned down. The heat release rate started to increase rapidly 90 seconds after the wood cribs caught fire. In the test with a fire load level 1, the maximum heat release rate of 4743.4 kW was reached at 244 second. In the test with fire load level 2, a maximum heat release rate of 5050.9 kW was reached at 497 second. In the test with fire load level 3, a maximum heat release rate of 4446.9 kW was reached at 677 second.

• Journal of the Korean Society of Safety
• /
• v.13 no.4
• /
• pp.59-70
• /
• 1998

In this study, response time index(RTI) of standard and quick response type sprinkler head are measured and compared through ramp and plunge test in heated wind tunnel. Also discharge rate and water distribution, actual delivered density(ADD), fire test with wood cribs are performed to compare the fire suppression capability and the operation time and temperature between standard and quick response type sprinkler head.

• Fire Science and Engineering
• /
• v.25 no.5
• /
• pp.62-68
• /
• 2011

A series of fire tests involving realistic solid combustible materials was conducted to quantify the heat release rate and investigate the fire growth characteristics during the initial fire growth stage. For these tests, single/double wood cribs, urethane cushion having polypropylene covers and wood crib on nylon carpet with urethane carpet padding were used as a fuel source. The fire growth coefficient of the solid combustible materials was quantified and the fire growth characteristics were compared with the $t^2$ fire scenario. The mean effective heat of combustion was evaluated by the total mass loss of fuel and total energy release concept and examined the effect of the ventilation and fire condition. The present study provides the practical information on the fire growth characteristics of solid combustible material to design to a set of fire scenarios for the fire risk analysis.

• Fire Science and Engineering
• /
• v.17 no.3
• /
• pp.26-30
• /
• 2003

This paper presents a study on the analysis for false alarm of heat detector using HRR(Heat Release Rate). And it is represented to threshold value and domain of false alarm. The HRR threshold value of false alarm is calculated to use parameters obtained by small scale fire-experiment. The experiment is conducted to measure detector activation time and flame spread of wood cribs fire, etc. The results show that HRR threshold value of Fixed type detector is 20.24 kW and rate of rise type detector is 13.59 kW, respectively.

• Journal of the Korean Society of Safety
• /
• v.8 no.2
• /
• pp.72-77
• /
• 1993

Available Safe Egress Time(ASET) is the time available for occupants to evacuate safely In compartment fire, and It depends on the time of fire detection and hazardous conditions. The purpose of thls study Is to provide an analytical basis and experimental data for estimating the fire growth in compartments and the available safe egress time, and to compare the experimental data with those proposed equations. As a result, hazard order Is poison to CO, descent of smoke layer, poison to $CO_2$, burn to hot smoke layer, and lack of $O_2$, ASET is lengthened in this order. Also, The more fire load is increased, the more ASET is shorted.

• Journal of the Korean Society of Safety
• /
• v.34 no.3
• /
• pp.28-35
• /
• 2019

Dry water is a core-shell structured powder which comprises a very fine water core covered with hydrophobic silica particles. Recently, the dry water has attracted attention as a new type of fire extinguishing agents. However, characteristics of the dry water as a fire extinguishing agent have not been revealed until now. To our best knowledge, this is the first work to uncover effects of particle size of the dry water on the fire extinguishing performance. Pristine dry water, which has heterogeneous particle size distribution, was carefully separated by sieving method into three fractions which were a small size (ca. $110{\mu}m$) fraction, a medium size (ca. $220{\mu}m$) fraction and a large size (ca. $400{\mu}m$) fraction. Microscopic observations confirmed the effective separation of dry water's particle size. In extinguishing tests of wood cribs fire, the medium size dry water showed most excellent fire extinguishing performance, as compared to other dry waters having small (ca. $110{\mu}m$) and large (ca. $400{\mu}m$) particle size. The good performance of the medium size (ca. $220{\mu}m$) dry water may be attributed to the balance between cooling effect of the water core and smothering effect of the silica particles. It is also revealed that small size dry water has poor flowability than large size dry water.

• Fire Science and Engineering
• /
• v.33 no.1
• /
• pp.50-59
• /
• 2019

Experimental and numerical studies on the fire characteristics according to the distance between the fire source and sidewall under the over-ventilated fire conditions. A 1/3 reduced ISO 9705 room was constructed and spruce wood cribs were used as fuel. Fire Dynamics Simulator (FDS) was used for fire simulations to understand the phenomenon inside the compartment. As a result, the mass loss rate and heat release rate were increased due to the thermal feedback effect of the wall in the compartment fire compared to the open fire. As the distance between the fire source and sidewall was reduced, the major fire characteristics, such as maximum mass loss rate, heat release rate, fire growth rate, temperature, and heat flux, were increased despite the limitations of air entrainment into the flame. In particular, a significant change in these physical quantities was observed for the case of a fire source against the sidewall. In addition, the vertical distribution of temperature was changed considerably due to a change in the flow structure inside the compartment according to the distance between the fire source and sidewall.