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<font face="Arial">{bang lesson for the day}<br>
<br>
Actually, something that explodes may or may not be chemical in
nature (see BLEVE). An explosion is a rapid release of gas
without specifying the source of the gas.<br>
<br>
Deflagration may or may not produce an explosion, it would
normally need to be confined to allow the container to burst.<br>
<br>
A detonation is when the reaction moves through the material at
greater than the speed of sound in that material. A material
detonating does NOT need a container to cause an explosion. A
small pile of flash powder on a shelf in a shed will reduce the
shed to toothpicks.<br>
<br>
You can tell a detonation a couple of ways. One is you get a
CRACK sound before or instead of the BANG.<br>
<br>
Second, you can often see the shock wave traveling through the air
if you're lucky to be far enough back. It will also raise dust on
the ground. At the begging of this video<br>
<a class="moz-txt-link-freetext" href="http://interstellar.com/photos/Western_Winter_Blast_2008/Burn_Pile_WWB-19.wmv">http://interstellar.com/photos/Western_Winter_Blast_2008/Burn_Pile_WWB-19.wmv</a><br>
there will be a small bang, then you'll see a semicircular dust
cloud appear on the ground followed by everything else going off.
The dust cloud was from a Barney doll that was sitting on some "special
sauce".<br>
<br>
Oh, and black powder (the real stuff, not a substitute) is a bit
funny. In small quantities like you would use in a gun it
deflagrates. If you have a larger quantity of it, it will "go
high order" and detonate. Doesn't need a container. That's why
you find it hard to get. The substitutes like Pyrodex are
actually a version of smokeless powder that's been speed adjusted
to mimic black powder burning in a gun. But, it will NOT
detonate. That's why you can buy it mail order and have UPS leave
20 pounds of it on your porch without so much as a signature.<br>
<br>
Oh, and regular smokeless powder? Single base stuff is
nitrocellulose (gun cotton) with stabilizers and graphite powder
to reduce static. When it first came into use it didn't have the
stabilizers in it and could go off because it was Tuesday. This
is the same stuff old movie film was made of, model airplane dope,
and also ping pong balls. Really!<br>
<br>
Double base adds nitroglycerin, the active component in dynamite.<br>
<br>
</font><br>
<div class="moz-cite-prefix">On 06/30/2015 02:42 PM, Chip Wood via
Stagecraft wrote:<br>
</div>
<blockquote cite="mid:55930D2A.4060300@gmail.com" type="cite">
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<div class="moz-cite-prefix">Where is the boundary in "speed"
between deflagration and explosive? Is there a jump or is it a
continuous ramp up depending on source? Or is this just experts
letting us in on the details or something practical we can use
for pyro staging?<br>
<br>
Chip 1</div>
<br>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Jerry Durand, Durand Interstellar, Inc. <a class="moz-txt-link-abbreviated" href="http://www.interstellar.com">www.interstellar.com</a>
tel: +1 408 356-3886, USA toll free: 1 866 356-3886
Skype: jerrydurand
</pre>
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