Fire Safety Science Digital Archive

The theoretical basis for using liquid carbon dioxide and liquid nitrogen in place of water as a general extinguishing agent for fires has been examined. This examination indicates that there is unlikely to be a case for using liquid gases unless the fire is such that the use of water would result in a large part of the water not being vaporized. It is suggested that there may be scope for the use of liquid gases: (a) Where the present use of water causes substantial water damage. (b) Where the extinguishing agent cannot be made to reach the source of fire directly. (c) Where a large flow of agent needs to be projected into a building from outside. (d) For certain large outdoor fires e.g. aircraft crash fires. For the latter two applications liquid nitrogen is likely to be more effective than liquid carbon dioxide because of the inherent inability of the latter to remain a coherent liquid at atmospheric pressure. Operational problems likely to be encountered in bringing liquid gases into large-scale use at fires are outlined.