Firefighting - Asphyxiating A Fire

Asphyxiating A Fire

In some cases, the use of water is undesirable:

• some chemical products react with water and produce poisonous gases, or even burn in contact with water (e.g., sodium);
• some products float on water, e.g., hydrocarbons (gasoline, oil, alcohol, etc.); a burning layer can then spread and extend;
• in case of a pressurised fuel tank, it is necessary to avoid heat shocks that may damage the tank: the resulting decompression may produce a BLEVE;
• electrical fires where water would act as a conductor.

It is then necessary to asphyxiate the fire. This can be done in different ways:

• some chemical products react with the fuel and stop the combustion;
• a layer of water-based fire retardant foam is projected on the product by the fire hose, to keep the oxygen in air separated from the fuel;
• carbon dioxide.