What does carbon dioxide do to a flame?

Answer 1

Oxygen is required to have a flame. If there is too little oxygen available, the flame will go out.

Natural atmospheric levels of carbon dioxide have no effect on the flame. If the CO2 concentration is high enough, it can extinguish the flame by lowering the amount available oxygen e.g. covering a candle with a jar.

Answer 2

Carbon Dioxide is a heavy gas, commonly stored compressed in a cylinder for use as a fire extinguisher. The gas does not react with most substances and so does not support combustion on anything less reactive than carbon.

When released from high pressure containment, the gas rapidly expands. Since the expansion requires heat, the gas takes the heat from its surroundings. When directed at a fire then the first effect is to remove heat from the fire. Secondly, the gas displaces the air involved in the burning process and thus removes the oxygen necessary to sustain the combustion. The net effect is that carbon dioxide tends to put out fire in the area that it is used.

There are other effects too. The force of the blast of carbon dioxide can spread flammable materials if used without caution or proper training, and as the carbon dioxide disperses with time, materials previously burning may re-ignite. Carbon dioxide is of limited effectiveness for extinguishing fire in unconstrained locations.

Answer 3

Carbon Dioxide may be cool as it leaves its compressed container, but the fact is that the chemical has a higher density than Oxygen, therefore it displaces the Oxygen around the area it was sprayed. Fires can't burn without Oxygen, and Carbon Dioxide isn't combustible.

Answer 4

It will 'smother' the flame, putting out the fire. It displaces oxygen because it is heavier than oxygen (44 g/mole vs 32 g/mole).

Answer 5

Carbon dioxide extinguishes a flame by displacing oxygen. When carbon dioxide is released onto a flame, it reduces the available oxygen for combustion, causing the flame to go out.