Why co2 extinguisher is not suitable to put out class A fire?

Answer 1

A class A extingquisher is intended to put out things that when burned, leave an ash--hence class A. They are usually some form of liquid or plain water. A class B fire is a liquid fire and using a class A extingquisher will only add volumn to the liquid that is burning making it a larger area to put out. With a class B fire you need something that will smother the fire without making it spread out even farther.

Answer 2

A CO2 extinguisher will safely put out a Class A fire. However, water will also, so perhaps that is a more readily available and cheaper alternative.

Answer 3

The gas emitted from a CO2 extinguisher may not be concentrated enough for long enough to completely stop a Class A fire (ordinary fuels), but it is better than nothing.