Aguila Blanca
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JohnKSa said:
But not by sparks.
article said:
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Fire at the Gun Range
- Thread starter PolarFBear
- Start date
But not by sparks.
That's sort of interesting. I had never thought of exactly what constitutes a spark and what doesn't.But not by sparks.
It seems that the various definitions for "spark" are, as one might expect, quite general and many would certainly categorize small particles of glowing metal as sparks. That seems to be consistent with general usage. People talk about sparks being thrown off by a grinder and many of those "sparks" are actually bits of glowing metal.
Here are a few definitions for spark.
a small fiery particle thrown off from a fire, alight in ashes, or produced by striking together two hard surfaces such as stone or metal.
an ignited or fiery particle such as is thrown off by burning wood or produced by one hard body striking against another.
An incandescent particle, especially:
a. One thrown off from a burning substance.
b. One resulting from friction.
an ignited or fiery particle such as is thrown off by burning wood or produced by one hard body striking against another.
An incandescent particle, especially:
a. One thrown off from a burning substance.
b. One resulting from friction.
The pictures in the article definitely depict a shower of glowing/incandescent/fiery particles being thrown off the target.
But even if we were to decide on a definition of "spark" that ruled out small glowing metal fragments, it seems it would be a difference without distinction. There doesn't seem to be any question that even copper and copper/lead bullets can start fires under the proper condition. Debating the specific definition of "spark" doesn't change that.
John, this whole thing is making me think a lot harder than I want to tonight. Electric spark? A bit of plasma excited by an electron packet passing through it. A spark created by other energies? A particle raised to incandescent heat that is in the process of oxidizing. Would a grinder strike a spark in a flow of nitrogen, or a welder in a flow of helium?
A third type, maybe Copper sparks? Is that just a bit of metal that absorbed so much energy that it reached incandescent heat, but hasn't created a self sustaining state of 'burning'?
A steel spark will continue to build heat as it burns, as will ignited magnesium, these things generate heat during combustion, as do many bio organic things, or even charcoal, right? But since a spark off of copper doesn't combust, won't that tiny little packet of heat energy dissipate so easily that igniting a piece of cloth should be literally impossible?
The entire question is whether a bullet or other object can dump enough energy onto another surface to blast off superheated particles, don't you think? Oh, heck yes. part of the energy energy of forty grains of powder smashing into steel, no matter what the impacting object is releases a metric fartload of energy and could break off a chip of steel that would absorb enough energy to ignite. But, both lead and copper are too soft and malleable to release that sort of energy, right? Those impacts spread the kinetic energy out both in time and into deformation, right?
One of my most important questions, is why do ferrous metals spark, but most non ferrous metals won't when ground by a super hard stone or ceramic? Here's my thought. Steel has a brittle structure and it is broken off in chips at high speed, and they ignite in air because smashing them off generates so much heat. Iron is also very active with oxygen, especially in the form of steel. Most common non ferrous metals, aluminum, copper, lead, that stuff is scraped off at temps too low to ignite the metal, and ordinarily, if they do strike a spark upon impact, it would cool very rapidly, because it contains very little energy.
Here's something that I just can't fit into my tired head. Brass on a grinder smears and leaves brass alloy dust. Grinding steel leaves oxide. Watch it grind, and you can see those superheated particles literally explode as they pass through the oxygenated air. Particles break up.
So, it seems to me that malleable,not particularly active metals shouldn't under ordinary circumstances strike a spark, observation over centuries kind of supports that. But unusual circumstances that can't be understood by a dolt like me will absolutely allow sparks of some sort to pop off of a malleable metal.
If a person packs enough ke, through velocity, into a lead projectile, say maybe 20,000fps, would you expect it to dissolve into a fireball upon impact with the proverbial immovable object? I would, I guess...
A third type, maybe Copper sparks? Is that just a bit of metal that absorbed so much energy that it reached incandescent heat, but hasn't created a self sustaining state of 'burning'?
A steel spark will continue to build heat as it burns, as will ignited magnesium, these things generate heat during combustion, as do many bio organic things, or even charcoal, right? But since a spark off of copper doesn't combust, won't that tiny little packet of heat energy dissipate so easily that igniting a piece of cloth should be literally impossible?
The entire question is whether a bullet or other object can dump enough energy onto another surface to blast off superheated particles, don't you think? Oh, heck yes. part of the energy energy of forty grains of powder smashing into steel, no matter what the impacting object is releases a metric fartload of energy and could break off a chip of steel that would absorb enough energy to ignite. But, both lead and copper are too soft and malleable to release that sort of energy, right? Those impacts spread the kinetic energy out both in time and into deformation, right?
One of my most important questions, is why do ferrous metals spark, but most non ferrous metals won't when ground by a super hard stone or ceramic? Here's my thought. Steel has a brittle structure and it is broken off in chips at high speed, and they ignite in air because smashing them off generates so much heat. Iron is also very active with oxygen, especially in the form of steel. Most common non ferrous metals, aluminum, copper, lead, that stuff is scraped off at temps too low to ignite the metal, and ordinarily, if they do strike a spark upon impact, it would cool very rapidly, because it contains very little energy.
Here's something that I just can't fit into my tired head. Brass on a grinder smears and leaves brass alloy dust. Grinding steel leaves oxide. Watch it grind, and you can see those superheated particles literally explode as they pass through the oxygenated air. Particles break up.
So, it seems to me that malleable,not particularly active metals shouldn't under ordinary circumstances strike a spark, observation over centuries kind of supports that. But unusual circumstances that can't be understood by a dolt like me will absolutely allow sparks of some sort to pop off of a malleable metal.
If a person packs enough ke, through velocity, into a lead projectile, say maybe 20,000fps, would you expect it to dissolve into a fireball upon impact with the proverbial immovable object? I would, I guess...
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There was a remark, I believe the op, that mentioned spalling. Rebar is terrible steel, full of flaws and loose bits. When a super high energy impact breaks off a bunch of particles from a contaminated or very brittle piece, could those small particles that have just been smashed to dust start to oxidize on impact, creating a self sustaining combustion, a burning spark that has enough energy to ignite a single fiber on the rough target paper, and that tiny, little packet of heat could push other tiny fibers into combustion, eventually creating a larger, self sustaining combustion?
This is EXACTLY WHAT HAPPENS when Otis next door tosses a cigarette butt onto his dry lawn, and that little bit of barely smoldering material creates an inferno, a few molecules at a time.
I think that I'm going to add something that seems appropriate. Earlier last summer I was working on a project that involved wood and steel, I was working on finishing the wood at the same time I was working on some steel. Sparks off of my grinder reached about a foot away from the wheel and ignited the 0000 steel wool pad. I smelled it as it smoldered, it wasn't really visible.
If I had fibrous cloth or paper next to it, oil or solvent, and I had taken a lunch break, boy, that would have sucked, and it was all because of a few whit hot sparks.
This is EXACTLY WHAT HAPPENS when Otis next door tosses a cigarette butt onto his dry lawn, and that little bit of barely smoldering material creates an inferno, a few molecules at a time.
I think that I'm going to add something that seems appropriate. Earlier last summer I was working on a project that involved wood and steel, I was working on finishing the wood at the same time I was working on some steel. Sparks off of my grinder reached about a foot away from the wheel and ignited the 0000 steel wool pad. I smelled it as it smoldered, it wasn't really visible.
If I had fibrous cloth or paper next to it, oil or solvent, and I had taken a lunch break, boy, that would have sucked, and it was all because of a few whit hot sparks.
I'm not claiming to know the root cause.I think non sparking tools,such as berrylium copper,are a different issue.
They do not strike at 2800 fps.They do not suddenly remove and spew a quantity of steel into whatever is beyond.
I don't know much about depleted uranium anti-tank projectiles.My understanding is that when the projectile strikes the tank hull,the material that wreaks havoc inside the tank is called "spall" and it is composed of the steel tank hull.Pictures of this seem pretty hot and sparky.
Now I'll consider a different angle. As a prototype machinist/moldmaker,my employer invested some in my education. I attended seminars by both General Electric (who makes Lexan) and a rather brilliant consultant named John Klese. We discussed long polymer carbon chains,etc.
The instructors spoke specifically about the difficulty of both drilling and tapping Lexan (polycarbonate)
Even hand tapping with water as a lube,enough local heat can be generated to melt the surface of the material. That melt/cool can create number of problems.
It was explained that the tapping operation was releasing tremendous heat by breaking these long carbon chain molecules. Enough to melt the threads at hand tapping speeds.
I imagine steel has similar carbon bonds,and a 2800 fps bullet of any material releases the heat from those bonds as it spews steel out the back of the plate.
It does not come out as a nice little round plug.
I was there.I fired the shot,I watched the target smoke.It was flaming when I got there.
No amount of skeptical feedback will change that.The technical minutia may have value in determining root cause,but it does not change the outcome. The target caught on fire. Some folks get so wrapped up in the academics of what they "know" they dismiss what can be observed.
And we shooters who are responsible enough to not want to start fires might take heed.
Including shooting up old derelict cars or washing machines,etc we may come across. Fires are very bad PR. It would be bad if some of the California fires were attributed to shooting steel junk.
They do not strike at 2800 fps.They do not suddenly remove and spew a quantity of steel into whatever is beyond.
I don't know much about depleted uranium anti-tank projectiles.My understanding is that when the projectile strikes the tank hull,the material that wreaks havoc inside the tank is called "spall" and it is composed of the steel tank hull.Pictures of this seem pretty hot and sparky.
Now I'll consider a different angle. As a prototype machinist/moldmaker,my employer invested some in my education. I attended seminars by both General Electric (who makes Lexan) and a rather brilliant consultant named John Klese. We discussed long polymer carbon chains,etc.
The instructors spoke specifically about the difficulty of both drilling and tapping Lexan (polycarbonate)
Even hand tapping with water as a lube,enough local heat can be generated to melt the surface of the material. That melt/cool can create number of problems.
It was explained that the tapping operation was releasing tremendous heat by breaking these long carbon chain molecules. Enough to melt the threads at hand tapping speeds.
I imagine steel has similar carbon bonds,and a 2800 fps bullet of any material releases the heat from those bonds as it spews steel out the back of the plate.
It does not come out as a nice little round plug.
I was there.I fired the shot,I watched the target smoke.It was flaming when I got there.
No amount of skeptical feedback will change that.The technical minutia may have value in determining root cause,but it does not change the outcome. The target caught on fire. Some folks get so wrapped up in the academics of what they "know" they dismiss what can be observed.
And we shooters who are responsible enough to not want to start fires might take heed.
Including shooting up old derelict cars or washing machines,etc we may come across. Fires are very bad PR. It would be bad if some of the California fires were attributed to shooting steel junk.
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I'm not arguing about any of that . There is a huge amount of kinetic energy in that bullet that is converted into heat upon impact the bullet, smashing up and being deformed absorbs a bit of energy and warms up. The rest of that energy is transmitted to the steel plates as vibration, with that being turned into heat, and even noise. All of that energy is either used up in destroying the bullet, scattering the piece, or is transferred to the plate as heat and some is absorbed by vibration and just dumped into the air. All of the energy can be accounted for, just like tapping that plastic.
Whatever happened to cause a spark hot enough to char paper and set up the chain reaction resulting in a fire, I can't guess, but the bottom line is that your bullet had a lot of potential kinetic energy that was turned into heat by deforming and transferred into the rebar as movement.
We don't have to know how it happened and I'm never going to figure it out. What we know is that your bullet contains some of the energy released by the powder, and that bullet will expend it in several ways that release heat.
If that steel was covered with flakes that absorbed a lot of heat, known as you say, spall, those flakes might have set a fire.
When I was a kid, I thought that brakes couldn't get Hot. I felt a disk, it wasn't hot. So, I didn't get it. But they do, don't they?
I'm not a scientist. I am glad that I can at some point say'huh. I don't get it'. I don't have to understand it to make it true. Gravity works.
Whatever happened to cause a spark hot enough to char paper and set up the chain reaction resulting in a fire, I can't guess, but the bottom line is that your bullet had a lot of potential kinetic energy that was turned into heat by deforming and transferred into the rebar as movement.
We don't have to know how it happened and I'm never going to figure it out. What we know is that your bullet contains some of the energy released by the powder, and that bullet will expend it in several ways that release heat.
If that steel was covered with flakes that absorbed a lot of heat, known as you say, spall, those flakes might have set a fire.
When I was a kid, I thought that brakes couldn't get Hot. I felt a disk, it wasn't hot. So, I didn't get it. But they do, don't they?
I'm not a scientist. I am glad that I can at some point say'huh. I don't get it'. I don't have to understand it to make it true. Gravity works.
Brian,
The article I linked to has a lot of information that may help answer some of your questions and/or provide insight into this issue.
Here's an example:
The test fired bullets into steel targets. One finding was:
"Thermal infra-red video and temperature sensitive paints suggested that the temperature of bullet fragments could exceed 800°C."
A piece of metal at 1500°F definitely has the potential to start a fire in paper or wood, paper or dry grass (all of which have ignition temperatures less than 600°F) , whether or not we agree that the metal fragment meets the definition of a "spark".
The article I linked to has a lot of information that may help answer some of your questions and/or provide insight into this issue.
Here's an example:
The test fired bullets into steel targets. One finding was:
"Thermal infra-red video and temperature sensitive paints suggested that the temperature of bullet fragments could exceed 800°C."
A piece of metal at 1500°F definitely has the potential to start a fire in paper or wood, paper or dry grass (all of which have ignition temperatures less than 600°F) , whether or not we agree that the metal fragment meets the definition of a "spark".
Absolutely true, the only question is whether a hot piece of metal has enough heat energy to ignite the particular product. Doesn't take much to start tissue paper or cotton balls smoldering, and just that one spark of 'fire' can create a chain reaction and catch. The biggest difference between just a hot piece of metal and a hot piece of burning metal, such as a piece of ground off steel, or maybe even thermite, is that the burning piece is releasing chemical energy as well as just the stored heat.
there are people who could break this down. not me.
This thing even involves the question of specific heat or heat capacity. Specific heat is the measure of how much energy must be added to a kilogram of a substance to raise that kilogram of substance one degree celsius, iirc. Brass, copper, iron, lead, have low specific heat figures, it takes very little heat to raise that temperature, therefore there isn't a lot of heat release when it cools down. Beryllium, however, has a much higher specific heat figure. It will take four times as much heat input measured in calories to raise that kilogram of beryllium one degree. it may take a torch a minute to heat up a piece of lead but you will need to run that torch longer to burn more gas and push more heat into the metal, and then, you will release more heat when the metal cools.
Stored heat. the way one of my chem professors put it, would you be smarter to put your hand in a cup of boiling water or a quart of water at 120 degrees until the water cools? There is a lot more heat stored in the quart of 120 degree water, so it will burn you worse IN HYPOTHETICAL CIRCUMSTANCES.
sure, the quart will release far more heat. But a cup of boiling water will scald the skin off.
I'm not sure what my point was.
there are people who could break this down. not me.
This thing even involves the question of specific heat or heat capacity. Specific heat is the measure of how much energy must be added to a kilogram of a substance to raise that kilogram of substance one degree celsius, iirc. Brass, copper, iron, lead, have low specific heat figures, it takes very little heat to raise that temperature, therefore there isn't a lot of heat release when it cools down. Beryllium, however, has a much higher specific heat figure. It will take four times as much heat input measured in calories to raise that kilogram of beryllium one degree. it may take a torch a minute to heat up a piece of lead but you will need to run that torch longer to burn more gas and push more heat into the metal, and then, you will release more heat when the metal cools.
Stored heat. the way one of my chem professors put it, would you be smarter to put your hand in a cup of boiling water or a quart of water at 120 degrees until the water cools? There is a lot more heat stored in the quart of 120 degree water, so it will burn you worse IN HYPOTHETICAL CIRCUMSTANCES.
sure, the quart will release far more heat. But a cup of boiling water will scald the skin off.
I'm not sure what my point was.
PolarFBear
New member
Fire Marshal proclaims--
As a "wrap" to this story. Local Fire Marshal, TBI, arson investigator, etc. have all agreed that a customer shooter did in fact fire a tracer round into the back stop. The back stop was constructed with shredded rubber.
As a "wrap" to this story. Local Fire Marshal, TBI, arson investigator, etc. have all agreed that a customer shooter did in fact fire a tracer round into the back stop. The back stop was constructed with shredded rubber.
In The Ten Ring
New member
Is this the right link?
http://wncn.com/2018/01/25/tracer-ammunition-ignites-fire-at-indoor-gun-range/
I have never been a fan of the rubber backstop....I would want angled steel such as I saw in a documentary once on guns.
http://wncn.com/2018/01/25/tracer-ammunition-ignites-fire-at-indoor-gun-range/
I have never been a fan of the rubber backstop....I would want angled steel such as I saw in a documentary once on guns.
a rubber backstop as spoken would have been a literal backstop, with a steel plate and pit full of shredded tire. The secondary backstop was a set of large sheets of what is essentially tire material, black tire rubber laminated with threads of some sort, possibly fiberglass in many brands, but some use plain thread.
This is just a backstop intended to stop or catch as much backscatter as is possible, there must be a steel plate behind with a pit to catch bullets.
Tracer rounds are hot. Very hot. They are a metal mixed with a binder, an oxidizer, and an element that will add color to the flame. The metal is generally magnesium, I don't remember what the oxidizer is. Magnesium burns very hot and brightly. the binder prevents this oxygen fed fuel from blowing off instantaneously like a flash bulb. the colorant, likely strontium, burns along with the magnesium.
A tracer is essentially no different than a firework rocket or the stars from them. Black powder or another material. the powder is treated with a retardant. magnesium or aluminum are added to burn it brighter. There are many different metallic salts that either in a combination or alone burn off with the high temperature magnesium to add colored light to the hot white light of the magnesium. Sometimes plain iron is added to the flare for color.
So, a tracer intended to reach out for hundreds of rounds was discharged in a single pit, blasting extremely hot gasses into a pit/pile of easily ignited rubber shreds. Then, you have a tire fire. There are other types of steel backstops. a standard angled sheet of steel deflects the bullet downward into a spiral shaped tube. the round tube forces to bullet to run round in a circle and expend its energy as friction. as bullets pile up, there is no need for the thing to spiral around the steel, it's just locked in place and the impact energy is expended against the piled bullets instead of the steel snail as friction.
A truly high tech range like the nra has at one of their facilities has a continuous oil feeder that lubricates the steel. It is obviously a non-flammable oil such as glycols or silicones, something that would be able to withstand the high heat of friction and resist sparking from any steel particles that hit it. The oil's purpose is to reduce friction heat, prevent some lead buildup, and to capture any sparks that are caused by bullets on occasion.
This is just a backstop intended to stop or catch as much backscatter as is possible, there must be a steel plate behind with a pit to catch bullets.
Tracer rounds are hot. Very hot. They are a metal mixed with a binder, an oxidizer, and an element that will add color to the flame. The metal is generally magnesium, I don't remember what the oxidizer is. Magnesium burns very hot and brightly. the binder prevents this oxygen fed fuel from blowing off instantaneously like a flash bulb. the colorant, likely strontium, burns along with the magnesium.
A tracer is essentially no different than a firework rocket or the stars from them. Black powder or another material. the powder is treated with a retardant. magnesium or aluminum are added to burn it brighter. There are many different metallic salts that either in a combination or alone burn off with the high temperature magnesium to add colored light to the hot white light of the magnesium. Sometimes plain iron is added to the flare for color.
So, a tracer intended to reach out for hundreds of rounds was discharged in a single pit, blasting extremely hot gasses into a pit/pile of easily ignited rubber shreds. Then, you have a tire fire. There are other types of steel backstops. a standard angled sheet of steel deflects the bullet downward into a spiral shaped tube. the round tube forces to bullet to run round in a circle and expend its energy as friction. as bullets pile up, there is no need for the thing to spiral around the steel, it's just locked in place and the impact energy is expended against the piled bullets instead of the steel snail as friction.
A truly high tech range like the nra has at one of their facilities has a continuous oil feeder that lubricates the steel. It is obviously a non-flammable oil such as glycols or silicones, something that would be able to withstand the high heat of friction and resist sparking from any steel particles that hit it. The oil's purpose is to reduce friction heat, prevent some lead buildup, and to capture any sparks that are caused by bullets on occasion.