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Kenny
05-21-2010, 07:25 PM
Would a bullet bouncing (ricocheting) off a metal item cause a spark which would ignite a gas filled room?

Failing that how would an open flame in a room full of gas react together?

Basically I need to start a fire in a cafe (greasy spoon) to hide fingerprints so that the MC will not be IDed by fingerprints. It's got to be a quick method so no wiping down surfaces.

Thanks in advance,
Kenny

Kathie Freeman
05-21-2010, 07:45 PM
Only if it were steel- or copper-jacketed. I don't think a straight lead bullet would.

Stanmiller
05-21-2010, 07:59 PM
Would a bullet bouncing (ricocheting) off a metal item cause a spark which would ignite a gas filled room?

Failing that how would an open flame in a room full of gas react together?

Basically I need to start a fire in a cafe (greasy spoon) to hide fingerprints so that the MC will not be IDed by fingerprints. It's got to be a quick method so no wiping down surfaces.

Thanks in advance,
Kenny

Sorry. Neither copper nor lead make a spark when glancing off anything. If the concentration of gas was just right (around 15% I believe) the muzzle flash could ignite the gas. Then the MC gets toasted along with everything else in the place.

What's wrong with a simple lit match tossed over his shoulder as he goes out the door?

--Stan

Anaximander
05-21-2010, 08:27 PM
Yeah, it's pretty rare for bullets to spark much - the energies involved in the impact tend put the bullet's stagnation temperature above its melting point, so it's essentially liquid during impact, which is why they can deform so much. If the bullet was a tracer then that might do it, but tracers tend to be limited to military use, and most commonly higher-calibre stuff like .50cal, neither of which really suits this scenario.

Your best bet is probably a simple match, or maybe leave something flammable on a cooker so it'll catch fire shortly thereafter, giving the perpetrator time to put some distance between them and the scene before it goes up and draws attention.

Noah Body
05-21-2010, 08:32 PM
A tracer round might do what you want, and without getting the shooter in the blast zone. Of course, the shooter will pretty clearly mark his position in the attack, and I'm not convinced a tracer would really generate enough energy to ignite a gas-filled room. And I've fired thousands and thousands of tracers in my life time.

On a lark, I did find this handy site (http://intuitor.com/moviephysics/), though.

Drachen Jager
05-21-2010, 08:36 PM
Tracers don't do it. The only way for a tracer to ignite gas would be if it lost nearly all of it's momentum. The problem is the bullet is just moving way too fast, the air displaced by it's movement is more than enough to extinguish any small flame that might get started.

I've actually seen it done with gas cans and tracers, all it made was a mess. No fire.

One way I HAVE seen used in a movie that could work is to hold the barrel of the firearm so the muzzle is touching the gas. That way the powder which is still burning when it's discharged will ignite the flame.

Summonere
05-21-2010, 08:39 PM
Would a bullet bouncing (ricocheting) off a metal item cause a spark which would ignite a gas filled room?

Failing that how would an open flame in a room full of gas react together?

Basically I need to start a fire in a cafe (greasy spoon) to hide fingerprints so that the MC will not be IDed by fingerprints. It's got to be a quick method so no wiping down surfaces.

Thanks in advance,
Kenny

It does in the movies. :)

My experience with bouncing bullets is that steel core bullets spark, but standard composition ones (lead core, copper jacket) don't. At least with handguns. I've not seen any of the rifle rounds hit anything close enough to tell. Thus I'd be inclined to think that the chances of sparking a fire would be greater from the muzzle blast than sparking bullets.

Example: fellow I know was in Fallujah when six of his men entered a building, gunning for some insurgents who had been shooting at them from an upper floor. On the lower floor of that building, nozzles had been knocked off of several propane tanks. The soldiers entered the gas-filled ground floor and immediately engaged the enemy. The resultant gunfire torched everyone. It wasn't sparking bullets that set off the gas, but muzzle flash.

Open flame in a room full of gas = fire/explosion.

Noah Body
05-21-2010, 08:54 PM
Tracers don't do it. The only way for a tracer to ignite gas would be if it lost nearly all of it's momentum. The problem is the bullet is just moving way too fast, the air displaced by it's movement is more than enough to extinguish any small flame that might get started.

I've actually seen it done with gas cans and tracers, all it made was a mess. No fire.

One way I HAVE seen used in a movie that could work is to hold the barrel of the firearm so the muzzle is touching the gas. That way the powder which is still burning when it's discharged will ignite the flame.

Yeah, like I said, I'm not convinced it would work. If the gas density is enough, perhaps it might--when viewed through ANVIS-6 NVGs, which have gallium arsenide tubes that read into the IR spectrum, I've seen tracer trails left in the air well after the round has passed through, but I'm not smart enough to know if the heat is enough to cause a secondary ignition.

Noah Body
05-21-2010, 08:56 PM
Example: fellow I know was in Fallujah when six of his men entered a building, gunning for some insurgents who had been shooting at them from an upper floor. On the lower floor of that building, nozzles had been knocked off of several propane tanks. The soldiers entered the gas-filled ground floor and immediately engaged the enemy. The resultant gunfire torched everyone. It wasn't sparking bullets that set off the gas, but muzzle flash.

Open flame in a room full of gas = fire/explosion.

Heh, former Green Beanie Michael Yon penned an article where he hit a propane tank with several 5.56mm rounds while assisting a wounded LTC in Iraq, and his fear of blowing themselves up didn't materialize. :D

Summonere
05-21-2010, 09:45 PM
Heh, former Green Beanie Michael Yon penned an article where he hit a propane tank with several 5.56mm rounds while assisting a wounded LTC in Iraq, and his fear of blowing themselves up didn't materialize. :D

I suspect that's entirely possible. Problem with B. and company was that the ground-floor room in the house they entered was already full of gas when they entered, at least down there. Bad guys firing at them from above prompted the six fellows below to shoot back.

Reports from the time indicated that gunfire from the pre-entry fighting had knocked the valves off the propane tanks and otherwise made them leaky, sans initial conflagration. By the time the six entered, gas saturation was ripe for ignition. When the shooting resumed, fire was the result.

I've read some of Yon's blog. He seems to be doing good work. Still there, is he?

Noah Body
05-21-2010, 10:01 PM
In Afghanistan now, I believe.

He still posts at the Michael Yon Online Magazine (http://www.michaelyon-online.com/).

Stanmiller
05-21-2010, 10:50 PM
In Afghanistan now, I believe.

He still posts at the Michael Yon Online Magazine (http://www.michaelyon-online.com/).

That the guy that wrote DANGER CLOSE?

Noah Body
05-21-2010, 11:20 PM
Ayup, though I have to admit I've never read it.

GeorgeK
05-22-2010, 05:09 PM
Sorry. Neither copper nor lead make a spark when glancing off anything.
--Stan

I've seen it. Well actually, my daughter saw it. I was looking at the target (a rooster that had started raping hens to death). I shot it through the neck and the bullet hit a metal T-Post and sparked. It was a copper jacketted high velocity round (for an SKS...Russian ammo for a Chinese weapon if it matters)

Whether that spark would be enough to light gas?...That probably depends on whether it's gasoline or natural gas or something else.

Summonere
05-22-2010, 06:24 PM
Plenty of non-ferrous materials will spark, but they toss off sparks at lower temperatures than steel, that's why things like brass wrenches exist (I used a few brass tools while working with jumbo loads of fuel and other combustibles, once upon a time).

Not disputing anything. Just adding info.

hammerklavier
05-22-2010, 06:26 PM
Most russian and chinese ammo is steel cased, and most of it also has a steel core (although it is not armor penetrating). There is a common 5.56 round you can get that also has a steel core, although the jacket is copper.

Stanmiller
05-22-2010, 06:40 PM
Agreed, G, S, and H.

Before I could stop him, some bud of my son nailed the swinging steel plates on our range with steel-core Wolf AK rounds. Didn't penetrate (half-inch mild steel plate) but made impressive little craters and produced visible sparks. Didn't do the chains any good. The ricochet scared the little twerp pretty good when it zinged by his ear. Served him right but gave me cold sweats about the liability issue.

My impression from the OP that the round would be a handgun caliber. I don't know of any off the top of my head except the AP round for the FN 5.7 that has a steel core (and that one may be tungsten, I haven't checked.)


--Stan

RJK
05-22-2010, 07:14 PM
Disconnect a gas valve. open a hot water tap. When enough hot water runs out, the hot water tank will ignite, igniting the room full of gas. BOOM.

Stanmiller
05-22-2010, 07:39 PM
Cool. Or tie the safety valve down then fiddle with the thermostats and 2 hours later the heater will explode, destroying the place.

Wait. The OP said quick explosion, right? Rats.

--Stan

jennontheisland
05-22-2010, 07:51 PM
It'll take a bit of time for the gas to fill the room, so I'm not sure how quick a method that is.

But.

Most restaurants cook on gas. There will be pilot lights in the oven. When there's enough gas, that pilot will blow the room all on its own.

jclarkdawe
05-22-2010, 09:35 PM
I don't know much about sparks and bullets, but I do know a fair amount about gas and structures. Being on a fire department will do that for you.

A municipal restaurant will use natural gas, while more rural restaurants will use propane. You can tell the difference externally as propane will have a tank and natural gas is piped in. With natural gas, there's a little (about six inch) cover located outside the building to shut off the gas.

I don't remember how large the supply line is for either system, but it isn't that big. This matters because a building has X cubic feet of space. Normally the amount of either gas in the air is extremely minimal. Propane is heavier than air and I believe natural gas is also. When the value is open (for example, turning on a burner), the gas leaks outs, relatively slowly filling the room to explosive levels.

However, it doesn't fill the room evenly. The concentration will be heaviest nearest the source, and slowly expand throughout the room. And people use this principal safely every day of the week. I used it for dinner last night, and didn't blow up a thing. I turned on the burner, releasing propane. A second or so later, the igniter on the stove, creating sparks, caused the small gas bubble to explode and my burner was lit.

Now the implications of this to your problem. Let's say that your guy opens all of the burners, without hitting the igniters. (By the way, most ovens now have a safety device to prevent this happening.) Or he's more advanced and saws the gas line in half. Gas starts being released, creating a bigger and bigger bubble. But this isn't a quick process. And it's going to be a while before it builds up enough to blow up an entire room (like measure in hours, not minutes).

Meanwhile, as this bubble is expanding, if it hits an ignition source, you get a boom, although a lot smaller than you want. Fire departments get little booms all the time. Big booms are the exception.

Your idea could work, but it's going to take a while and most likely will misfire. On the flip side, how many people know this?

Best of luck,

Jim Clark-Dawe

Kenny
05-23-2010, 04:08 AM
Thanks for all the help guys.

Another idea I had was cooking oil. My new current idea is to turn some cans of it over where he wants to hide his ID, then set fire to the deep fat fryer, and finally ignite the oil on the ground. Maybe he could chuck a cup of water into the deep fat fryer (carefully) to speed up the resulting fire.

After I sat down and thought about the spark I remembered how hard it was to light the gas cooker at my parents with the spark provided by the cooker.

Stanmiller
05-23-2010, 04:21 AM
Thanks for all the help guys.

Another idea I had was cooking oil. My new current idea is to turn some cans of it over where he wants to hide his ID, then set fire to the deep fat fryer, and finally ignite the oil on the ground. Maybe he could chuck a cup of water into the deep fat fryer (carefully) to speed up the resulting fire.

After I sat down and thought about the spark I remembered how hard it was to light the gas cooker at my parents with the spark provided by the cooker.

Mythbusters did that. Get the oil burning then dump in a quart of water. Seems like they got about a 20ft fireball out of it. But it takes prep time.
--Stan

Kenny
05-23-2010, 01:26 PM
Mythbusters did that. Get the oil burning then dump in a quart of water. Seems like they got about a 20ft fireball out of it. But it takes prep time.
--Stan

I've seen it done. Open camp fire, burning oil, and a water gun. It was impressive. So guys that's why you don't put out chip pans by splashing them with water! :)

Compared with the other options I feel it'll be the quickest method of sorting the cafe out to hide traces of the MC.

Stanmiller
05-23-2010, 03:27 PM
I've seen it done. Open camp fire, burning oil, and a water gun. It was impressive. So guys that's why you don't put out chip pans by splashing them with water! :)

Compared with the other options I feel it'll be the quickest method of sorting the cafe out to hide traces of the MC.

K,
I thought there was a time constraint.

What about the obvious? A couple gallons gasoline sprinkled over everything. Lit match. Whoosh.
-Stan

bonitakale
05-23-2010, 04:29 PM
How about potato chips? They're supposed to work well and be hard to trace.

Kenny
05-24-2010, 01:33 AM
K,
I thought there was a time constraint.

What about the obvious? A couple gallons gasoline sprinkled over everything. Lit match. Whoosh.
-Stan

He's in a cafe when a hitman comes to kill him but he gets the jump (well he is the MC) but he does not want the police to know he was there. Gasoline would work really well, and thanks for the suggestion, but I'm guessing that cooking oil would do almost as well and he would have that on hand.

Kenny

Stanmiller
05-24-2010, 08:10 AM
How about potato chips? They're supposed to work well and be hard to trace.

Potato chips? :Shrug: Please explain, Ms. Kale.

Chase
05-24-2010, 09:38 PM
Don't you guys watch TV? All bullets spark off glass windshields, fiberglass car bodies, lake surfaces, and . . . yes . . . even potato chips.

Also, when even a .22 Short bullet goes into a heavy-coated victim, blood ERUPTS out the front, and the victim is thrown six yards to the rear. The trick is to hold the gun sideways.

Pay attention, folks!

Drachen Jager
05-28-2010, 10:44 PM
Cooking oil would be hard to light unless it was hot. It's not going to go up like crazy even once you do light it unless it's in a deep fryer or has something to act as a wick. Kitchen fires with cooking oil can be very nasty but the oil really has to be hot to burn out of control.

If you're interested, here is what a hot cooking oil fire looks like.

http://www.eatmedaily.com/2009/11/deep-fried-turkey-disaster-videos-youre-doing-it-wrong/

#6 gives a good idea of how hard it is to light even hot cooking oil. They're TRYING to start a fire, even with a burner underneath it doesn't catch that quickly.

Drachen Jager
05-28-2010, 10:53 PM
I just had a thought though... Most commercial kitchens have gas stoves and ovens. If your cafe does some cooking (I presume so if they have oil!) they'd probably have gas. Cut the line and light a candle or something that will burn slowly in the next room. KABOOM!

jeseymour
06-02-2010, 02:29 AM
I'm not sure if I'm remembering this right, but an old spy buddy of mine gave me an arson idea once that works well with a restaurant. Turn up the deep fryer and put a two liter soda bottle full of water in it. Leave the building. Once the fryer gets really hot, the soda bottle will explode and send hot fat all over the place, which should ignite something. I guess there's no guarantee though. :)

Nivarion
06-02-2010, 10:51 PM
My suggestion if he wants a quick fire would be to scatter paper napkins everywhere and light the napkin/toothpick dispensers on fire. If the place has cloth tablecloths then I'd light those on fire too.

And the draperies/curtains. And if it has any strong liquor around break those up too.

I'm also a massive pyro and can light most of everything on fire.