> > That doesn't explain it entirely. I'm with Gahalia's original question. Why would *water* explode a small, bubbling candlewax fire into a Nine Foot Mushroom Firecloud of Doom?
> >
> > I suppose that if it is a Class B fire, the part which is ignited (prior to the water-dumping) is the vapour-air bubble immediately above the wax. You'd think water in a sufficient quantity should *decrease* the overall heat-energy content (of the exothermic combustion reaction) and bring it closer to going out. Instead, the water vaporizes explosively and in fact seems to fuel the explosion. Huh?
>
>
> I haven't read up on this, but here's a theory: the heat is enough to separate the oxygen and hydrogen in the water, but they immediately react with each other again, spreading the heat in said nine-foot-mushroom-of-fire, which would then be cooler than the actual oil fire.
>
> Fuzzpilz

Nice theory, no cigar. :-) The hydrogen-oxygen bonds in water are covalent linkages, meaning they are very tightly bound together. I think I've heard that temperatures in excess of 2800°C are required to split the O-H bond. Well, if we were persistent and tried -- purely as a thermochemical experiment -- to set my house on fire, by pouring home heating fuel down the chimney and throwing a few barrels of coal briquettes into the firebox, the hottest I could get a roaring chimney-flue fire going is about, oh, 1700-2000°C. So unless I can get my hands on a thermonuclear explosive of some sort, :-) I'm afraid that not even a blast furnace can heat up to the necessary degree of heat required to split hydrogen away from oxygen, even when using a pure O2 atmosphere. I think we'll have to think about it from another direction.

Wolf "water fountains and a Class B chimney fire to magically create the Ninety Foot Mushroom Firecloud of Doom: FWOOOOOOOM" spirit