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Leon[_7_]

On 5/6/2013 12:21 PM, wrote:
On Mon, 6 May 2013 17:14:58 +0000 (UTC), Doug Miller
wrote:

Larry Blanchard wrote in :

On Mon, 06 May 2013 11:34:44 +0000, Doug Miller wrote:

Do you *really*
think that the pressure developed by an air compressor (9 to 10
atmospheres is typical) is anywhere nearly comparable to the pressure
developed by igniting gunpowder in a small confined volume?

I found this:

"One gram of blackpowder gives you 718 calories of heat, 270 cubic
centimeters of gas,"

So if we knew how much powder the bombers used and the volume of the
pressure cooker we could come up with a pressure.

Typical pressure cooker is about 5 liters. It would take 5000 / 270 = 18.5 grams of black
powder to produce 5 l of gas at 1 atm pressure -- so developing a pressure of, say, 25
atmospheres would require 25 times that much: 463 g, or just over a pound.

And that's assuming there's nothing else in the pressure cooker, which we know is not the
case. Suppose the interior volume was reduced by half, by the ball bearings and nails
these guys added. In that case, we're talking a free volume of only about 2.5 liters, and a
kilogram of powder would generate pressure well over 100 atmospheres.

Assuming that it didn't rupture first.

Pressure cookers are designed to release pressure, that hissing you
hear, at 15 lbs.