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View Full Version : Does powder in a firecracker burn or explode?


tpcollins
March 23, 2009, 04:21 PM
I made an error recently in a previous post referring to a powder charge in a muzzleloader exploding insted of burning and some kumbaya singers corrected me on that point. But I got to thinkng. If I take a keg of powder and pour a trail of powder along the ground and sit the keg with powder left in it at the end, what really happens when I light the trail? It seems the powder on the ground would burn but what happens when the flame gets to the keg? Does the keg burn or explode? What about a firecracker, a stick of dynamite, or a hand grenade? Do those things burn or explode? Is there a difference in terminology when the powder is loose in the open versus housed in a container? Thanks.

claymore1500
March 23, 2009, 05:37 PM
I can't speak for the powder in a keg, or a grenade, but I have taken the powder out of several M-80 firecrackers and put it into a small box to check just what you are asking about, I lit a makeshift fuse and got the he## outa there, The powder burned, but VERY fast, I'm talking about a half dozen M-80's in the box gone in a split second, with a blinding flash of light.


Kind of impressive!

Microgunner
March 23, 2009, 05:44 PM
Burn

armsmaster270
March 23, 2009, 06:12 PM
They all burn but confinement causes the explosion in low order explosives

CLASSIFICATION OF EXPLOSIVES

Low Explosives: Low explosives deflagrate rather than detonate. Their reaction velocities are 2000 to less than 3000 feet per second. Black powder is a good example. pg 27

http://www.nps.gov/history/history/online_books/npsg/explosives/Chapter2.pdf
Low explosives - Their detonation velocity rate is below 3,280 feet per second. (Black powder rate is 1,312 fps) High explosives burn or detonate at a rate of above 3,280 f.p.s. (Dynamite-about 9,000 f.p.s.; RDX - 27,500 f.p.s.)

http://www.jus.state.nc.us/NCJA/hazmat.pdf
A Normogram for determination of pressure waves as they relate to 'burn rate'.

http://www.usace.army.mil/publications/eng-manuals/em1110-2-3800/c-3.pdf
Other so-called insensitive explosives can also be used safely, including compositions of 80-90% RDX or HMX, the explosive powders or crystals being thoroughly coated with plasticized polymer (20%-10%) and wherein the HMX is usually in a bimodal crystal form (see "Explosives and Propellants (Explosives)"; Vol. 10, 4th Ed. Encyclopedia of Chemical Technology, especially pp. 55-56). Primasheet (Ensign-Bickford Co.) has a burn rate of 23000 ft. per second, i.e. 7010 meters per second; the aforementioned HMX has a burn rate of 8800 meters per second; and PETN has a burn rate of 8260 meters per second. http://www.patentstorm.us/patents/6200615-description.html

Dr Ed

Ginormous
March 23, 2009, 06:14 PM
Deflagrate. :D

tpcollins
March 23, 2009, 06:21 PM
Armsmaster270 - that was impressive! Thanks.

MrNiceGuy
March 23, 2009, 06:23 PM
explosiveness is just a measure of it's rate of burn.

in other words, it's both

B.L.E.
March 23, 2009, 08:18 PM
My understanding of the difference between detonation and deflagration:

Deflagration is an extremely rapid burning, the reaction spreads through the explosive substance by heat transfer. It's a lot like a really fast forest fire, one burning tree sets the next one on fire.

In a detonation, a shock wave travels through the explosive substance and it is the sudden compression that the shock wave performs that causes the explosive material to react. This shock wave travels through the material at the speed of sound. The speed of sound through solids and liquids is many times faster than the speed of sound through air.

Interestingly, if you simply set fire to most common high explosives, they simply burn instead of detonate. It takes a powerful blasting cap to set up that initial shock wave to make the detonation happen.

ClemBert
March 24, 2009, 11:11 PM
tpcollins -

Yup, I remember that thread and how some dude after parsing your words couldn't wait to jump down your throat and correct you. That was inappropriate of them to be ass-hats. They could have educated you in better fashion.

I recently made a post about black powder hunters "running through the woods" and got correct by a well intentioned helpful person who wanted to assure me that these hunters did not "run" through the woods and rather were stealthy, yada...yada...yada (paraphrased). Anyhow, while I appreciate all his help, because he was helpful afterall, I was questioning why my words were being scrutinized so harshly. Geez, I called my mom today and asked where dad was and she told me he was running around town taking care of errands. Am I to believe my 73 year old dad really was "running around town"?

Anyhow, unfortunately the internet and internet forums have become a place where there is always someone waiting to "set you straight" and sometimes they do in a manner that is unwelcome. Oh well, that dude who straightened you out as I recall was trying to be helpful.

BTW, I've witnessed firecracker powder stuffed and packed in a steel pipe with a long fuse and lit. The result was a tremendous explosion. :eek: Uh oh, here come the PC police... ;)

Kumbaya singer then corrects me and says: "The powder rapidly burned and then the rapid excessive pressure caused the pipe to explode. It wasn't the powder that exploded...blah, blah, blah."

pax
March 24, 2009, 11:25 PM
When one of my sons was in junior high, his science fair project was an investigation of that very question. We had a lot of fun selecting various modern smokeless powders, along with black powder, for him to test.

He laid each type of powder down a long thin line inside a metal rain gutter in the yard, set up a "bunker" that he could hide behind while wearing all sorts of protective gear, and produced an awesome video of himself looking with boredom at the stopwatch while each powder took from 30 seconds to around 2 minutes to burn the 6-foot trail. At the beginning of the video, he explained what he was looking for, defining an "explosive" reaction in terms of the time it would take to burn the entire trail of powder. An explosive would have detonated in less than some tiny little fraction of a second, burning from end to end literally before he could have hit the stopwatch.

At the end of his video, he neatly summed up the information by pointing out that different powders burn at different rates, but all of them burned rather than exploded. He then added that when fast-burning material is confined in an enclosed space -- such as inside a firearm cartridge or a lead pipe -- the pressure from the expanding, burning gases has nowhere to go, and tends to leave rather abruptly.

He had a lot of fun putting that project together. The most difficult part he had with the whole thing was getting approval from his supervising teacher. She was convinced he was going to blow a huge hole in our front yard, and blow himself to smithereens! It took a lot of research on his part to get her the materials she needed to believe his assurances that there was nothing really dangerous about his experiment, apart from the inherent danger of playing with matches...

pax

Smokin_Gun
March 25, 2009, 02:05 AM
Controlled burn in a confined space produces Pressure for expulsion...:cool:

B.L.E.
March 25, 2009, 06:39 AM
BTW, I've witnessed firecracker powder stuffed and packed in a steel pipe with a long fuse and lit. The result was a tremendous explosion.

You could have filled that pipe with water and thrown it into a bonfire and gotten a similar tremenous explosion, and learned firsthand why boiler explosions were so feared in the days of steam powered riverboats.

Yet few of us think of water as being an explosive material.

Another way of making the distinction between high and low explosives is that high explosives can make a tremendous explosion when totally un-confined.

Scorch
March 25, 2009, 12:16 PM
I also remember the guy jumping on you to correct you in your other post. Seems like the internet brings out the "best" in some folks.

To answer your question, propellants like black powder and smokeless powder burn, not explode. Firecrackers are a mixed lot, some contain black powder, others contain flash powder (like they used to use in the late 1800s for taking photographs). Black powder burns because saltpeter releases oxygen when heated, flash powder burns because the chemicals in it oxidize very rapidly when heated. This rapid burning is called a conflagration (con= together, flagration= burning up, so burning all at once), caused by the heat and released oxygen from nitrates in the compound burning the hydrocarbon base materials. Burning propellants unconfined slows the release of oxygen and slows the burning. To stop a conflagration, just relieve pressure, and the material just burns.

Explosives explode, whether they are confined or not, caused by heat and shock. If you set fire to dynamite, for example, it will burn. If you shoot it or hit it while it is burning it will explode. Detonating caps, used to set off explosives, provide both heat and shock to detonate the material. Other sources of shock are electromagnetic radiation (like radio waves) or impact (like a rifle round), or a shock wave (from another explosion). Enough of a shock, and explosives will explode. Once an explosion starts, there is no stopping it.

I know, long story.

tpcollins
March 25, 2009, 04:02 PM
Thanks guys - in both respects. For a moment I thought my ex-wife was a member of this forum. :barf:

dcobler
March 26, 2009, 06:03 PM
Been wondering lately how many terms I could get wrong in just one post. Maybe later I will try let everyone know how it turns out.

Jim Watson
March 26, 2009, 06:23 PM
Some of the good old boys hereabouts claimed that they inserted a blasting cap into a can of Bullseye (40% nitroglycerine, balance nitrocellulose.) They said it went high order and left a substantial crater. But I wasn't there.

Dingoboyx
March 27, 2009, 11:17 AM
most powders burn if not confined, and go bang if they are (confined). Depending on speed of the powders burn rate, and the strength of the confinement will determine the resulting explosion. :D

Good idea to light the fuse and run like heck.... otherwise might loose your ears (and eyebrows):eek::D

Muzza

Dingoboyx
March 28, 2009, 07:56 AM
that "shock cord" I think he called it that they set off plastic explosives with, y'know when they implode buildings and wot not, he said if you layed a length of it from Sydney to Melbourne (about 800 kilometers) and lit it, it would reach the end in just over 4 minutes :eek: Now, thats fast :D

just thort ya might like to know :D

Muzza

Dragon55
March 28, 2009, 08:08 AM
All gunpowders burn. It's important to make that distinction because any material defined as explosive comes under a whole other set of laws. Yeah I know, confinement is what makes the 'explosion' but when has science had anything to do with the law.

Mike Irwin
March 28, 2009, 09:35 AM
"Some of the good old boys hereabouts claimed that they inserted a blasting cap into a can of Bullseye (40% nitroglycerine, balance nitrocellulose.) They said it went high order and left a substantial crater. But I wasn't there."


Maybe...

If they dug a small, deep, hole, dropped the can into the hole, and then tightly tamped the earth back down into the hole.

At that point the the ground would serve to confine the expanding powder gas and you'd have a better chance of something that looked like an explosion.

Just tossing the can out onto the ground?

I'd say not a chance. Blasting caps are designed to create a lot of shock, but unlike a primer, not a lot of flame. You need flame to adequately ignite nitrocellulose powders.

I'd say that some of the powder would have ignited, but that the pulse from the blasting cap would have split the can wide open and scattered most of the powder around without it igniting.

mykeal
March 28, 2009, 05:06 PM
I personally suspect the blasting cap itself made the 'substantial crater' and the powder just burned. Just my opinion, not having been there.

zxcvbob
March 28, 2009, 05:18 PM
A detonation does not need confinement. Deflagration does need confinement for an explosion. Confinement may cause a deflagration to burn fast enough to transition to a detonation wave. "Explosion" is an imprecise term that could refer to either. (Imprecise is sometimes a good thing)

I wasn't there when the alleged can of Bullseye was blown up with a blasting cap, but it's plausible that it detonated. It's also plausible that it was just scattered from the force of the cap and didn't do anything.

Jim Watson
March 28, 2009, 05:57 PM
That is about what I figured. It might have actually detonated the NG content of the Bullseye, or it might have been a good story flowing out of a supply of Schlitz and a campfire at the hunting club.

The authorities are SO unreasonable about scientific experimentation these days, else it might be tried again, with video.

pappy177
March 28, 2009, 07:31 PM
30 years of firework making , firecrackers are made from flash powder.
70%potassium perc , 10% dark alum powder. and it does explode.
Here is some unconfined.

http://www.youtube.com/watch?v=P0ZPfY28fsY

B.L.E.
March 28, 2009, 07:35 PM
That is about what I figured. It might have actually detonated the NG content of the Bullseye,

Nitro Celluose a.k.a. guncotton is an explosive also and just as capable of detonation.

w_houle
March 28, 2009, 07:48 PM
A low explosive is usually a mixture of a combustible substance and an oxidant that decomposes rapidly (deflagration (http://en.wikipedia.org/wiki/Deflagration)); unlike most high explosives, which are compounds.

Under normal conditions, low explosives undergo deflagration at rates that vary from a few centimeters per second to approximately 400 meters per second. It is possible for them to deflagrate very quickly, producing an effect similar to a detonation. This usually occurs when ignited in a confined space.

Low explosives are normally employed as propellants. Included in this group are gun powders, pyrotechnics such as flares and illumination devices .

Detonation is a process of combustion in which a supersonic shock wave is propagated through a fluid due to an energy release in a reaction zone. It is the more powerful of the two general classes of combustion, the other one being deflagration. In a detonation, the shock compresses the material thus increasing the temperature to the point of ignition. The ignited material burns behind the shock and releases energy that supports the shock propagation. This self-sustained detonation wave is different from a deflagration, which propagates at a subsonic rate (i.e., slower than the sound speed in the material itself). Because detonations generate high pressures, they are usually much more destructive than deflagrations. It is possible to get what is called sympathetic detonation from the shock wave alone.

Brisance is a measure of the rapidity with which an explosive develops its maximum pressure. It is also the reason why you do not want to put smokeless powder into a gun made for black powder

teeroux
February 24, 2010, 07:28 PM
explosiveness is just a measure of it's rate of burn.


No. Not all explosives and/or explosions are the result of something burning fast.

bedbugbilly
February 25, 2010, 04:32 PM
I'm no expert on explosives, chemistry or anything else and I'm not posting to ruffle any feathers . . . . . . I just thinking . . . . in order to have fire . . i.e. "burn" . . . you need 3 things - oxygen, fuel and heat . . . basically, isn't that what you are all talking about? burn or explode . . . . doesn't "explosion" come from the rapid expansion of gasses caused from burning? Several exam;les given - black powder in a barrel - cap goes off giving a source of heat to the fuel (black powder) mixed with oxygen in amongst the granules causes the powder to burn - it burns at a rapid rate in a confined space of the bore between the breechplug and the bullet - the gasses produced is what expels the bullet down and out the bore. In a fire cracker, the propelllent is confined in a closed space where there is oxygen, the fuse furnises the heat and walla, the propellent burns causing a rapid expansion of gasses confined in the container and the result is a "bang". As the one fellow pointed out from his experience, the propellent is not black powder but it is a rapididly burning compound that "flashes" (or burns) at a rate that will cause the desired effects of a loud bang. Anyone with firefighting experience that has seen a house "backdraft" will be able to relate to the same theory. A fire is contained within the walls and ceiling (actually forming a large container that is pretty well "sealed") - the fire goes through "stages" and eventually, due to a lack of oxygen, the fuel (paneling, carpet, furniture, etc.) is starved for oxygen . . . . for some reason . . . it might be an unsuspecting or inexperienced firefighter who opens a door to enter to fight the fire or takes out a window or it could even be a "burn through" . . . air (oxygen) is suddenly introduced into the confined space causing the fire to accelerate quickly and a rapid expanse of gasses occurs and again . . . walla . . . you get a "backdraft" or explosion. That is pretty simply put but for those who haven't had firefighting experience, it will give you an idea.
Just my thoughts on it and my 2 cents worth which probably isn't worth much. Thanks! :D

tyme
February 26, 2010, 01:47 AM
i.e. "burn" . . . you need 3 things - oxygen, fuel and heat . . . basically, isn't that what you are all talking about? burn or explode . . . . doesn't "explosion" come from the rapid expansion of gasses caused from burning?

High explosives vs low explosives.
http://en.wikipedia.org/wiki/Explosives#Low_explosives
http://en.wikipedia.org/wiki/Explosives#Type_of_reaction

TXGunNut
February 28, 2010, 11:33 PM
If you ship or order smokeless powder you will discover it is a highly flammable hazardous material. If you ship or order black powder you'll find it is classified as an explosive. Our government regulates the transportation of these materials. They wouldn't be wrong about this, would they?

muldoon55
March 16, 2010, 02:46 PM
I have on many occasions detonated bullseye powder with acetone peroxide as the detonating medium.It was detonated in everything from a ducktape wrapped freezer storage bag to a shaped charge capable of defeating 1in hardened steel plate(2oz charge)
This stuff is wicked powerful possessing the same detonation velocity as TNT
21000 FPS