We have proposed an inert gas, rubber-balloon extinguishing method which might increase the effectiveness of extinguishing flames and decreasing the amounts of agents needed for fire suppression. Hence, extinguishing experiments have been performed to further clarify possible extinguishing characteristics, mechanisms and scaling effects of this method. Carbon dioxide, nitrogen, argon and helium gases were used as the extinguishing agents. Methane-air and propane-air diffusion flames were formed on two different diameter, round porous plate burner and used as the targets for extinguishment. The extinguishing probabilities were measured, and the extinguishing processes were observed with a high-speed camera. As a result, an effectiveness ranking of an inert gas in the rubber-balloon extinguishing method was in agreement with that of a cup-burner method. Moreover, determinations of extinguishing limits were accomplished, defined as the minimum volume of the inert gas required for successful extinguishment of flames; these limits depended on the balance of the heat loss caused by an inert gas and the heat production within the flame, and also on the forming process of a flammable premixing layer near the surface of the burner. In addition, all the extinguishing limits were represented by a unique, constant relationship depending on the non-dimensional number of the ratio of the heat absorbing rate of the inert gas to the heat release rate of the flame multiplied by the Schmidt number of the fuel species.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.