[SML] Taiwan water park explosion

[Dougherty, Jim]

First, condolences and hopes for a good outcome for the people caught in that mess. That looked awful. 

Here are some definitions:

Flashover is the point at which all of the contents of a room or confined space have been heated to the point at which they release vapors that will support combustion, causing all combustibles to ignite simultaneously. It's all burning, not exploding, but still an exceptionally bad place to be, even in full turnout gear and scba. I've been told if you're more than 5' from the door in such a room you're not going to make it out, and firefighters are trained what warning signs to look for. 

Explosion is also oxidation (i.e. burning) but much more rapidly, sometimes aided by confinement (i.e. black powder on a table will burn, in a cannon barrel will explode) or a facilitating event (i.e. C4 will burn with a match but explode with a blasting cap; diesel will burn, add oxygen rapidly enough from another source and it will explode).

A backdraft is an explosion; it's the sudden explosive ignition of fire gases when oxygen is introduced into a superheated space previously deprived of oxygen. (Door's closed, fire got hot, plenty of fuel left and still hot enough to outgas but used up all the oxygen - door or window opened = bang). Also a bad place to be. 

Taiwan saw a dust explosion. And there's more than one answer to what can do that from your local grocery store. Small particles of any fuel can have a good enough fuel:surface area ratio to allow mixing with the O2 readily available in the air, so they don't need an additional oxidizer. Industrially, don't forget coal dust. Overheated bearings, static electricity or poor pyro planning can cause ignition. 

Another good reason to keep the shop clean. Also, there are good videos of all of these online to actually see the difference. 

-  Jim Dougherty
ATD Middlebury College Theatre Dept
Firefighter, Orwell VFD