Fires cannot burn without all three elements of the fire triangle being present; oxygen
, heat and fuel. Fire fighting uses various methods to remove at least one of these elements and suppress the fire. After fuel, the next most important element to remove is oxygen and this can be done in different ways depending on the type of fuel involved. In cases of gaseous suppression, gasses with a low oxygen content and chemical agents are used.
The initial priority is to isolate the supply of fuel. According to the fire triangle there are three elements required for a fire to burn; oxygen, heat and fuel. At least one of these must be removed to suppress a fire, and the first and easiest is usually fuel. This is done by switching off mains valves and shutting off ventilation. This stage of the process must be completed before agents are applied.
Environmentally friendly; naturally occurring inert gasses and synthetic gasses work to remove the oxygen in the atmosphere. While some can cause asphyxia in humans, they do not deplete the ozone layer in the same damaging way other fire fighting chemical compounds can.
Minimal clean up; suppression by carbon dioxide is a swift and effective method which works without causing any damage to the equipment it protects. Commonly used in data centres, libraries and archives, it kills the fire without destroying the systems at risk. CO2 systems do not leave water or residue, minimising the damage to equipment.
Hypoxic air systems are revolutionary in that they maintain the oxygen content in the atmosphere at a level which is too low for fires but still high enough to humans. This concentration is typically between 14.5 and 15.5%. For the system to work no other source of fresh air can be present and ventilation must be 're-circulatory'.