How fast does black powder burn.

Jag

Active Member
I could look in my old blasting manuals, but I doubt I would find any specific numbers on brisance, etc. As a blasting agent, black powder formulations have almost disappeared. Perhaps have by now. Going from memory, black powder deflagrates at around 1200 fps (which can vary greatly depending on things like containment, pressure, prill size, etc), while B-line, which many here would know as det cord), in comparison burns/detonates at 22,000 fps.

I only had one blasting job involving black powder way back when I briefly followed my dad and grandfathers into the mines, and that was at a quarry working under another ticketed blaster familiar with black powder. Black powder is used in some applications other than the normal forcite/xactex/ANFO formulas because it gives the rock more of a thump, rather than a smack.

In most mining, either underground or open pit, the idea is to shatter what you're blasting as much and as finely as possible. In quarrying granite, marble, etc, the idea is to break the rock absolutely no more than necessary to make it just small enough for machinery to handle it and get the chunks to the machinery that turns it into counter tops, tiles, headstones, etc.

There are a couple of businesses here that have racks of marble/granite slabs stood outside for display as though they were new cars sitting on a dealership's lot. Looking at the price tags on each of those raw slabs, they might as well be new cars for sale - and that's before they're ultimately cut to the finished size for whatever their purpose will be.
 

Missionary

Well-Known Member
"Det Cord" is a fine tool to have around.
Long ago I heard an old feller say "BP does not burn (when confined), it explodes". Summed it up pretty good for a young mind.
 

RBHarter

West Central AR
Air space in confinement is the pressure head stop in BP .
As a propellant burn rate is controlled by surface area . If you take raw grind and make a pellet of it , it's a rocket motor , press it into a block and grind it to F to FFFFg and the rate remains same but the kernels are consumed faster . Without compression it has a huge surface area but it's very porous making it functionally someplace between F and FFg .

It also operates in a curious place where it over runs air compression in confinement or maybe it isn't fast enough to keep up and the shock wave and the collision makes a mess . No airspace no problem ......now I just have to figure out why a hollow base isn't an airspace .
 

Bret4207

At the casting bench in the sky. RIP Bret.
"Det Cord" is a fine tool to have around.
Long ago I heard an old feller say "BP does not burn (when confined), it explodes". Summed it up pretty good for a young mind.



I was also under the impression that smokeless powders burn and black powder explodes. I know on the Haz Mat table they are in different sections.
 

JonB

Halcyon member
"Det Cord" is a fine tool to have around.
Long ago I heard an old feller say "BP does not burn (when confined), it explodes". Summed it up pretty good for a young mind.
So there I was, with a bottom half of a popcan, a small campfire, and some BP...No confinement.

I placed the popcan half, upside down over some coals, sprinkled a bit (50 grs or so) of BP onto the bottom indentation of the popcan. No flames anywhere. About 1.597 seconds later, Bang, I blinked and then there was pieces of aluminum shrapnel flying past my head. My buddy, after he stopped laughing, said I no longer had eye brows. The largest piece was found about 30 feet away.
 

BBerguson

Official Pennsyltuckian
I was also under the impression that smokeless powders burn and black powder explodes. I know on the Haz Mat table they are in different sections.
ive always wondered though, whats the difference between burning and exploding?
 

Missionary

Well-Known Member
If you would have put that BP in the can and crushed the can together you would really know the difference.
Very possible you test gave the BP a pre-heated condition thus the more violent deflagration.
I have ran strings of BP and never had Explosive combustion.
 

Spindrift

Well-Known Member
ive always wondered though, whats the difference between burning and exploding?
My understanding is this

-When something is deflagrating, the process of combustion is traveling through the medium by transfer of heat, at subsonic velocity. Deflagration is just a fancy word for «burning».

- When something is exploding, or detonating, the process of combustion is transferred through pressure
 

Edward R Southgate

Component Hoarder Extraordiniare
I always went by it having a shockwave.

Which only comes with containment . In the open you get a slow burn from smokeless ( or C4 lit with a match not a cap) and a flash from black but no boom to create a measurable shock wave . I know everyone already knows all of this but work is shut down due to a small ice storm and I'm bored . :rofl:
 
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RBHarter

West Central AR
EOD doesn't like it when things deflagrate , it leads to low order messes of disrupted.now unstable stuff and lots little booms that should have been 1 very large impressive boom .