"Ralph Mowery" wrote


While probably not strickly correct, there are high and low explosives.
The high explosives material go off almost all at once such as the C4.
The low explosives burn very fast, such as black powder.

Strictly put, there are a lot of terms regarding "explosions".

You refer to explosive materials, such as C4. Explosives are rated at feet
per second. C4, IIRC is somewhere around 26,400 fps, which means that if
you put 26,400 feet of it out there, it takes one second to go from one end
to the other. It is not sensitive to impact or friction. And technically,
it does not explode, rather detonates is the proper term. Black powder is
much much slower, as we have seen the black powder trail to the dynamite or
keg of powder as in the movies. (Black powder may or may not detonate
dynamite, depending on the stability of the dynamite.) It's just a fast
walking speed. C4 detonates at hypersonic speed, producing a much greater
shock wave than black powder, which essentially burns, but rapidly and
causes pressure within a confined space which usually powers a projectile
out an opening. Black powder can also be used for fracturing rock if it is
packed. Loose black powder will just make a lot of smoke.

http://en.wikipedia.org/wiki/Gunpowder
http://en.wikipedia.org/wiki/C-4_(explosive)


Then you get into vapor explosions, which are rapid combustion, and not
actually an explosion, as another knowledgeable poster pointed out.

Then there are BLEVE's, or boiling liquid expanding vapor explosion, which
is called an explosion, but it is just still another rapid combustion, but
these usually occur within vessels that keep the pressure in until something
lets go.

IIRC, there is a speed of burn where it technically becomes an "explosion"
and not a conflagration (uncontrollable burning) or rapid combustion. And
then there's "brisance" which is the rapidity at which it reaches it's
maximum speed or shattering ability, usually measured in feet per second.

It gets real technical. For some good youtube, google Seoul BLEVE. There's
a good one, IIRC, somewhere in Kansas where a rail car is blown a quarter
mile.

In common language, an explosion is anything that goes boom. In technical
talk, there are all sorts of levels of boom.

Conflagration would best describe the sparking off of twenty gallons of gas.

Steve

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