Why water puts out fire

Throw hydrogen on your fire, then throw oxygen. Looks like the same effect, must be the same effect. It turns out that these two things do not have the same effect on fire if you look beyond the similar flash of increased energy release. They have a similar result but through completely different mechanisms. Hydrogen affects only the fuel side. Oxygen only affects the oxygen side. If you were to compare the gases being released by the fire before and after you added the oxygen, there would be no difference.

All you did was accelerate the process that was already happening. Hydrogen, on the other had adds an extremely receptive fuel source. Hydrogen is so ready to oxidize that it has a hard time existing in its pure state here on Earth. This actually gives us a clue as to WHY water puts out fire. It is the same reason that carbon dioxide CO 2 is also a pretty good option throwing pure carbon dust on a fire would have a similar, albeit smaller, flare as throwing hydrogen on it.

Water puts out fire by creating a barrier between the fuel source and the oxygen source it also has a cooling effect which has to do with the energy required to convert liquid water into water vapor. This smothers the fire. The same thing would happen if you used the ashes that remained after a completely spent fire.

Or, as I mentioned before, CO 2. Since grease floats on water, the water cannot block the fuel grease from the oxidizer air. Now, if after reaching degrees, he sets them off the mercury will reach the temperature of the surrounding air much more rapidly.

Now, suppose we wish to boil all the water away, to evaporate it—in that case remember that in passing from water to steam the temperature is not raised even a degree, nor any fraction of one—could he not make it all evaporate instantly by raising the temperature a little?

We all know he could not ; that the fire has a degree of heat several hundred degrees higher, but the kettle must remains long time, while the water very gradually goes off in steam.

Why so? Because the water, in becoming steam, must take into itself a large amount of heat not shown by the themometer and as the heat can be added only gradually, the formation of steam is slow.

Now, in the large amount of heat which water can take up, and the fact that ordinary inflammables must be raised to a high temperature in order to burn, we have the cause of water putting out fire. Put a burning match into a very small drop «f water and it is extinguished, because of the very large amount of heat taken from the match in reducing the water to steam which renders the temperature of the match too far below degrees, or at least that far, if there is water enough, and so the carbon and its compounds forming the wood will no longer unite with the oxygen of the air.

For the same reason a hot iron thrust into the water is cooled, and water sprinkled on the floor cools the air, the heat of evaporation in the latter case coming from the air itself, thus cooling it.

Now, if we could find a fluid very plentiful, which requires more heat than water to make it boil, evidently we could put large fires out much more readily. Sign in. Forgot your password? Clarion Events Privacy Policy. Password recovery.

Recover your password. You can also put out a fire by smothering it with dirt, sand, or any other covering that cuts the fire off from its oxygen source. However, you can NOT put out a grease fire using water. A grease fire is oil that has caught fire.

Water and oil do not mix, so throwing water on a grease fire only splatters the burning oil. Always use a lid to put out a stove fire.