How much gas does one grain of gunpowder generate?

T

TXAZ

New member
This is a general inquiry, not specific to a particular gunpowder:
At standard temperature and pressure, how much gas volumetrically would a typical / average / nominal grain of gunpowder generate?

The question came up in physics class and I can handle the ballistics, but don't know much about powder.
 
Thanks for that insightful answer 74.
I previously googled (Bing'ed) and found a wide variety of incompatible answers and was hoping someone who is into reloading and understands the chemistry side of this could help.

I know the mass doesn't change, but determining the volume is not trivial from some of the parametrics I've seen.

Thank you.
 
I don't know the answer, but I can give you a really rough way to figure an approximate...

Take a cartridge, find the interior volume, the charge in grains, and the pressure generated when fired. Then just start cranking the numbers until you can find what volume one grain of powder gas would occupy at one atmosphere pressure.

or, you can Google it, someone has probably already done that, :D
 
Its outside my level of brain damage. I don't want my head to hurt.

I'm just going to remind you to consider the deterrent,such as graphite or calcium carbonate,a factor.

IIRC,not long ago there was a thread by a Gentleman who had inherited a rifle and some ammo from his Father. This Gentleman wanted to ID the powder his Father was using in the handloads. I think the thread title was about identifying powder in handloads.

Another gentleman posted a chart giving very detailed information about the composition of the powders likely,like 4895,4064,4350,etc. on the thread.

There might be something useful there.

Update: I found it. Credit to TFL member arlaunch for sharing it.

http://www.ilrc.ucf.edu/powders/sample_detail.php?powder_id=66
 
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It’s a spreadsheet that calculates more parameters based on grains of ______ powderthan I’m interested in.
I’ll have to figure how to upload it.
 
Physics class, they are probably looking for a more theoretical answer.

One grain of powder will yield one grain of gas (theoretically). How much volume in one grain of gas? It's a PV=nRT question. Simplify to Charles's law and you have, where V2 is the volume of gas:

V2=V1 T2/T1

T1 at STP is about 273K. You gotta find or assume T2 (5000K ?) You also gotta know V1 for the grain of gunpowder, so density is an input (an engineer would swag it).

They probably want the problem setup more than an actual answer.
 
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Niner4Tango said:
Physics class, they are probably looking for a more theoretical answer.

One grain of powder will yield one grain of gas (theoretically). How much volume in one grain of gas? It's a PV=nRT question. Simplify to Charles's law and you have, where V2 is the volume of gas:

V2=V1 T2/T1

T1 at STP is about 273K. You gotta find or assume T2 (5000K ?) You also gotta know V1 for the grain of gunpowder, so density is an input (an engineer would swag it).

They probably want the problem setup more than an actual answer.
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Well no. Some powders will leave residue due to impurities and the amount of gas generated will differ slightly.
 
At standard temperature and pressure, how much gas volumetrically would a typical / average / nominal grain of gunpowder generate?
Click to expand...

So, what is "standard temp and pressure"? 72F and one Atm pressure (call it 15psi?)

Gentlemen, correct me if I'm wrong, if we took a round where 50gr of powder generated 50k psi in X volume, then wouldn't the math say that 1 gr of powder would generate 1,000psi in X volume? and then to get 1psi, we multiply X by 1000, then to get standard pressure (15psi) we divide by 15?

All at standard temp, of course??

or am I completely off track here??
 
MTT, correct. I am assuming this is physics class where they explore the theoretical. Once they have that down, they can start exploring the variables of the real world, like incomplete combustion, etc.

44 AMP, STP for physics is usually 0 deg Celsius, 273K. But for aviation and other cool stuff it's 15 deg C and 29.92 in hg.

I bet the problem statement is "What is the the volume of gas once it exits the barrel and is now at atmospheric pressure". So, guessing P1=P2. Otherwise the volume of the gas would just be the volume of its container.
 
This is a good question. I bet some powder companies have charts that answer this more definitively about their products.
 
Niner4Tango said:
MTT, correct. I am assuming this is physics class where they explore the theoretical. ...
Click to expand...

Close. The question actually was "Could we blow up a balloon with gunpowder, and how much would it take?" (Assuming you didn't burn the balloon)
That's a politically much more palatable question than asking about bullet in a chamber.
 
It wouldn't take much gunpowder (black powder) to blow up a balloon, a small firecracker would more than suffice, I would think.

Now, inflating a balloon, (without rupturing it) is a different matter. :rolleyes:

I discovered an intense dislike for certain "physics" problems, ever since the first one I found that made no sense.

Guy dives in a pool, swims to the far end, then swims back, climbing out exactly where he got in. Fine. Except that the "problem" they wanted answered was to give the formulae "proving" he didn't go anywhere.

guess I'm just a bumblebee, who doesn't know that advanced math proves I can't fly...:rolleyes:
 
A real world application for the question might be auto air bags.. I would think propellants and charges were researched extensively toward inflating a bag with propellan.
 
44 AMP said:
...
I discovered an intense dislike for certain "physics" problems, ever since the first one I found that made no sense.

Guy dives in a pool, swims to the far end, then swims back, climbing out exactly where he got in. Fine. Except that the "problem" they wanted answered was to give the formulae "proving" he didn't go anywhere.

guess I'm just a bumblebee, who doesn't know that advanced math proves I can't fly...:rolleyes:
Click to expand...

Technically he made a round trip, and his path length could have been large, but his net "displacement" (where he started vs. where he ended up) was *0*.
However, the total amount of energy he used was significantly more than *0*.
Depends on specifics of the question.
 
Guy dives in a pool, swims to the far end, then swims back, climbing out exactly where he got in. Fine. Except that the "problem" they wanted answered was to give the formulae "proving" he didn't go anywhere.
Click to expand...
There's a formula proving that he didn't do any "work", using the scientific definition of "work", but there's not one showing "he didn't go anywhere".
guess I'm just a bumblebee, who doesn't know that advanced math proves I can't fly...
Click to expand...
It proves no such thing.

https://www.businessinsider.com/bees-cant-fly-scientifically-incorrect-2017-12

http://www.todayifoundout.com/index...-flight-does-not-violate-the-laws-of-physics/

https://www.snopes.com/fact-check/bumblebees-cant-fly/

https://rationalwiki.org/wiki/Bumblebee_argument
 
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