Ultrafine Spray of Gas-Water Compositions Investigation for Fire Extinguishing Systems

The analysis of information about domestic and foreign installations of the volumetric fire-extinguishing with gas-water compositions is carried out. Pneumoacoustic sprayers of original design were developed, which make it possible to obtain a gas-water composition containing fire-extinguishing gas and water droplets of the ultrafine spray (10–60 microns). It is shown that gas-water compositions combine the advantages of fire-extinguishing gas and fine-sprayed water, since the volumetric method of gas fire-extinguishing and the cooling effect of water are preserved. The deposition (movement) of drops of the gas-water composition occurs together with the fire-extinguishing gas; therefore, the gas-water composition of the ultra-dispersed spray can be conventionally considered as a whole, i.e., new extinguishing agent. It is noted that the most promising is the application of gas-water compositions in the extinguishing of solid smoldering materials. In this case, when designing domestic fire-extinguishing installations, the amount of gas can be reduced by 20% or more, and the elimination of smoldering can be achieved by cooling with water from the gas-water composition. At the same time, the fire-extinguishing environment suitable for breathing for at least 3 minutes is formed in the room. The influence of gas in the gas-water composition on the dispersion of water droplets is studied. The sedimentation rate of water droplets in the gas-water composition was estimated. The droplet dispersion was measured by laser diffraction using the Malvern Spraytec system. It is shown that the substitution of nitrogen for argon or gas composition Argonite in the gas-water composition does not significantly affect the dispersion of droplets. Sedimentation of ultrafine spray water droplets in the volume of the room occurs within a few minutes. Nitrogen has the best characteristics for use in the gas-water compositions. Conducted studies make it possible to conclude that the installations based on domestic gas-water compositions allow for import substitution of the foreign analogues certified in Russia.

Safety Problem of Gaseous Extinguishing System in Underground Subway Station

The gaseous fire extinguishing agents CO₂, Halon 1301, and HCFC-BLEND A and a clean fire extinguishing agent are installed and operated in 85.5%, 6.19%, 4.14%, and 4.62% of the city railroad subway stations of Korea, respectively. The fire extinguishing halon gases Halon1301 and HCFC-BLEND A currently used in city railroad subway stations are already regulated globally because of global warming and ozone layer destruction.Moreover, the use of Halon 1301 is prohibited because of the development of alternative clean fire extinguishing gas. However, newly installing and operating CO₂, unlike the use of halon gas, has not been sanctioned. In particular, even though a fire extinguishing CO₂ facility has the serious safety problem of choking accidents occurring as a result of operation in a closed space because of the characteristics of a subway station, the situation has not been improved. The Organisation for Economic Co-operation and Development designates CO₂ as the major substance causing global warming and forcibly allocates the reduction of carbon emissions to member countries through a reduction policy. Therefore, overall annual replacement of CO₂ fire extinguishing facilities installed and operated in subway stations is necessary, and the problems of fire extinguishing operation characteristics and maintenance of fire extinguishing gas facilities should be reviewed. The purpose of this work is to presentthe maintenance status of fire extinguishing gas facilities installed and operated in the city railroad subway stations of Korea. Furthermore, the preparation of measures and laws for preventing fatalities resulting from choking caused by fire extinguishing CO₂ facilities and for improving cooperation with the international environmental response is proposed.