maximum PSI

[kentactic]

i was just watching mythbusters and watched one of the special guys who work on the show put gunpowder in his bow and drill to aid in making fire and then it blew up and it made a little smoke no big deal..

but that got me thinking...whats the maximum PSI gunpowder can generate?...is it only limited by the amount of powder used or is amount not a factor and at any given amount the same maximum PSI will be created?

i realize that more powder in a given cartridge will create more PSI but what if you make containers the exact size as a given amount of powder thats extremely thick and wont explode some more some less and then seal it and ignite it... will all amounts of powder have the same PSI?

 

[Downzero]

Re: maximum PSI

Pressure = force / area

So, basically, it depends on how well you can confine it.

 

[kentactic]

Re: maximum PSI

ok then what is the maximum force created by gunpowder in order to input into that equation?

Lets assume perfect confinement. 6 inch thick steel around a small amount of gunpowder, maybe a table spoon. assuming the amount of powder wont change the maximum pressure.

 

[badbot]

Re: maximum PSI

IIRC a blank generates 20,000 psi.

your question needs the total volume of the chamber total volume of powder and the expansion ratio for the powder. the peak pressure will drop as it cools but if you do have perfect confinement the resulting pressure will be far over atmospheric even after returning to room temp. black powder is a fairly low power powder. someone has likely answered this somewhere but I have no idea.

 

[kentactic]

Re: maximum PSI

are we talking in the hundreds of thousands of PSI?

 

[treebasher]

Re: maximum PSI

A (Very) Short Course in Internal Ballistics:

http://www.frfrogspad.com/intballi.htm

 

[kentactic]

Re: maximum PSI

so i take it no one so far has the answer?

maximum potential PSI created by modern smokeless powder?

i dont have the area of the chamber or volume of powder because if i knew the ideal measurements then id probably already know the maximum psi potential aswell..

 

[Rafael]

Re: maximum PSI

As I understant it, Hartmut Broemel does the load-cell testing of most or all powders for Quickload, the interior ballistics package many people use.

Here is his contact info from the NECO site.

Ing. Hartmut Broemel, Neubrecker Weg 15, D-64832 Babenhausen, Germany, fax/phone (+49) 0 6073 688481 Reimer Johannsen GmbH, Haart 49, D-24535 Neumuenste,r Phone +49 4321 2758, Fax +49 4321 29325

If anyone knows the answer, he does.

 

[kentactic]

Re: maximum PSI

Thanks Rafael

 

[Downzero]

Re: maximum PSI

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kentactic</div><div class="ubbcode-body">ok then what is the maximum force created by gunpowder in order to input into that equation?

Lets assume perfect confinement. 6 inch thick steel around a small amount of gunpowder, maybe a table spoon. assuming the amount of powder wont change the maximum pressure. </div></div>

Under "perfect" confinement, the pressure would be infinite.

The amount of powder does change the max, because that represents the "force" in that equation.

The greater the amount of powder, and the smaller the area, the higher the pressure. The pressure could get VERY high. a 9mm case loaded too short with a fast powder can hit 80,000 PSI quickly.

 

[mis-guided child2]

Re: maximum PSI

...

 

[kentactic]

Re: maximum PSI

well the only way the force could be infinite is if the amount of powder you could stick into a given area was infinite. but its not.lets assume gravity compaction only.

bassically it would seem TO ME that the most pressure possible will reult from an area filled 100% with no way to escape.

raising that should only increase the size of the explosion not the pressure. kind of like irrigation lines. you have you main line that runs from the water meter. that lines STATIC PRESSURE will never change no matter what size pipe you run directly after it but the VOLUME of water that can escape the line in a minute (GPM) will change...but since theres no escape all pressure should be the same if filled to the max at any given area size.

but back to the origonal question....what IS that magic PSI number?

 

[DocB]

Re: maximum PSI

kentactic,

The expansion ratio for most smokeless powders is 77 to 1. So for what ever your original volume of powder, you'll get 77 times the volume of gas.

HTH,
DocB