Fire Safety Science Digital Archive

Inert gas, such as nitrogen, argon ord carbon dioxide, is able to extinguish the flame more cleanly than water and dry chemical extinguishing agent. However, to extinguish fire completely, large amount of inert gas is needed to be released at the vicinity of flame or into confined fire space. If a capsule is filled with an extinguishing inert gas, and ruptures due to contact with the flame zone, the high concentration extinguishing gas can be directly supplied to the flame. By using the capsule, it will be possible to increase the effectiveness and decrease the amount of use of the inert extinguishing gas in fire-fighting. In the present study, in order to clarify the fundamental characteristics of flame extinguishment by the inert gas capsule, extinguishment experiments of a methane-air laminar jet diffusion flame by using a soap bubble filled with nitrogen gas have been performed. Soap bubble is used as the nitrogen gas capsule. As a result, when the soap bubble bursts, the two different kinds of the filling gas flow are formed. The first flow is generated by the pressure difference between the inside and outside of the soap bubble. The second flow is generated by the soap liquid film dynamics. In the soap bubble extinguishment, these two flows of nitrogen gas extinguish the laminar jet flame. The first flow extinguishes the flame base locally, and the second flow leads to blow out the whole flame.