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Fire extinguishing

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Fire extinguishing refers to the extinguishing of a fire. The chemical powder extinguisher is nowadays used for pretty much any type of fire, however appropriate fire extinguishing assumes analysing the fire class first, and then selecting a (environmentally harmless) extinguishing agent. For powder extinguishers, this means using particulate matter (ie sand, soil, ...), and for foam extinguishers, this means using a ecological soap mixed with water. CO² and FM 200 extinguishers can be used as is (already ecological). Both however only work in confined spaces (indoors).

Fire classes

Comparison of fire classes
Class A Class B Class C Class D
Ordinary combustibles Flammable liquids Flammable gases Combustible metals
wood, paper, textile, artificial materials gasoline, diesel, petroleum, paint thinner propane, butane magnesium, natrium, potassium, aluminum, alloys

Appropriate extinguishers depending on fire class

  • Class A: use water, or water + foam
  • Class B: use powder, or CO² or FM 200
  • Class C: use powder, or CO² or FM 200
  • Class D: use powder, or CO² or FM 200

Note: never use water with class B fires, the water can spread the combustible fuel making the fire larger. Foam with water can also not be used with B fires, for the same reason. CO² finally can be used indoors, but make sure not to use it when inside the room (can asphyxiate the user).

How the agents extinguish the fire

How the agents extinguish the fire
Extinguishing agent Cooling Expelling of oxygen Negative catalysis
water very good good no
water + foam very good very good no
powder no good yes (good)
CO² no very good no
FM 200 no no yes (very good)