From A to D: Classifications of Fire

Fires take on the characteristics of the fuel causing it to blaze. Note that paper fires burn differently from electrical and petrol fires, which is why they’re extinguished differently. Here’s a quick rundown of the different fires and the right type of extinguisher to use if such a scenario happens.

Class A

A Class A fire is your everyday kind of fire: paper, wood, and plastic as fuel. When extinguished with water, they’ll leave ash.

Class B

A Class B fire burns flammable liquids and gases such as petrol and natural gas. Water, being heavier than petrol and gas, won’t work well against a Class B fire; in fact, it may just spread out and burn further. Dry powder, foam, and carbon dioxide extinguishers deprive Class B fires of their fuel by bonding with the latter’s molecules.

Class C

A Class C fire involves flammable gases such as butane, propane, and methane. Dry powder extinguishers are the most effective for Class C fires.

Class D

A Class D fire is caused by combustible metals. While a slab of steel may not ignite, steel filings surely can. A Class D fire is more common in workshops and factories that work with or store metals, namely magnesium, titanium, and zirconium. Extinguishing a Class D fire with water is ill-advised because you’ll end up feeding the metal fire with hydrogen and oxygen to combust. Specially formulated M28 or L2 dry powder extinguishers are recommended.

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