AR15.Com Archives
 Why do something things blow up when shot?
20iner  [Member]
12/3/2004 8:17:51 PM
Why do propane tanks, gas tanks, etc blow up when shot?
Lead and Copper don't spark,
so what causes them to blow?
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MagKnightX  [Member]
12/3/2004 8:19:00 PM
Explosive decompression and the heat of the friction of gas being rapidly forced out?
GabbasaurusRex  [Team Member]
12/3/2004 8:20:54 PM
In the case of gas tanks in cars, they usually don't. Refer to Mythbusters.
MadMardigan  [Member]
12/3/2004 8:22:25 PM
A gas tank on a car wont blow unless there is room for vapors, you can actually put a match out in gas if you can avoid the vapors.
recoiljunky  [Member]
12/3/2004 8:23:45 PM
A lit object behind the target.
NoHarmNoFAL-01  [Team Member]
12/3/2004 8:25:00 PM
"Sparks”: airborne molten incandescent bits of metal.

When copper/lead hits steel at high velocity much energy is generated and is enough to cause metals to melt and "spark". The flammable gasses are ignited by the hot metals.
1Andy2  [Member]
12/3/2004 8:30:31 PM
Propane tanks do not explode when shot. I know this for a fact.

Several months ago, me and a friend were out behind his house at night hunting for skunks (they've got chickens, so this is necessary occasionally). My friend was completely out of shells for his scattergun, but he did have some ammo lyin around for his kimber 7mm 08.

We were walkin around (I had the light) and saw a black and white kitty move in front of some bushes . My friend brought his rifle up and fired. BOOM! He hit the skunk and the round passed right through and hit a propane tank hidden in the grass.

It took 15 minutes for the gas to run out of the tank. No explosion or fire resulted. But my freind got chewed out THOROUGHLY.
legonas  [Member]
12/3/2004 8:46:15 PM

Originally Posted By 1Andy2:
Propane tanks do not explode when shot. I know this for a fact.



+1, i have tried on many occasions to find the "perfect" reactive target, and propane isnt it. ive tried .22, 7.62x39, and a long time ago, .270 . not only did they not explode, they didnt even move when hit.

i remember one great experience as a kid was shooting a fridge with a .270 and having a huge trail of flame come out the back exit hole. i never knew why this happened.
1Andy2  [Member]
12/3/2004 8:50:23 PM
heh reactive target...


I haven't done this, but I've heard that aluminum reacts with Drano giving off Hydrogen gas.
What you could do is take a bottle of drano, put some aluminum foil strips in it, and then cover the neck with a balloon. Once the balloon fills with the Hydrogen, shoot it (from a distance).

Should be pretty reactive.
Fourays2  [Member]
12/3/2004 9:48:44 PM
hollywood?
hielo  [Team Member]
12/3/2004 9:49:14 PM
Kinetic energy.
444slayer  [Team Member]
12/3/2004 9:51:41 PM

Originally Posted By recoiljunky:
A lit object behind the target.



+1

Even tracers and incendiary rounds often will not ignite a propane tank, with out a flame in the vicinity.
cnorton  [Team Member]
12/3/2004 9:53:02 PM
Don't ponder, just enjoy.

BOOOOOOM!
LRRPS  [Member]
12/4/2004 12:54:52 PM
On 2 occasions, I have fired 5.56mm tracers into propane bottles only to see a big cloud of gas. A second tracer lit what remains from the gas. Unlike in Hollywood movies there were no explosion or great ball of fire.
sgtar15  [Team Member]
12/4/2004 12:55:57 PM

Originally Posted By hielo:
Kinetic energy.




Brain waves actually.

SGatr15

PS Ofcourse, if your brain is weak it won't work.
Juell  [Team Member]
12/4/2004 12:58:41 PM
If you put an aerosol can of a flammable nature into a paper grocery bag, light bag on fire, and then shoot the can inside the bag, it will make a good "Fwoomph!"
Or at least thats what I've heard..........
Triumph955i  [Team Member]
12/4/2004 12:58:50 PM
hasnt anyone seen dawn of the dead?

all you need is a flare and then shoot the tank.

it takes out a whole city block.

its true.

i saw it on a zombie movie.
Carabinero1979  [Member]
12/4/2004 1:05:41 PM
I've heard that if you light a road flare next to a propane canister, you will get the desired effect when you shoot the propane.

Anybody remember the simpson's episode when Bart becomes a hall monitor? He rides along with the springfield police on a chase where a car crashes into a tanker truck full of milk which bursts into flames?

Yeah, hollywood screwed us over with scientific misconceoptions. Hell, I remember as a kid trying to replicate half the cool tricks from the TV show McGyver.
Wombat  [Team Member]
12/4/2004 1:22:31 PM

hollywood


+1
thelastgunslinger  [Team Member]
12/4/2004 1:24:04 PM
Somethings blow up when you shoot then because they are filled with Tannerite.
Carabinero1979  [Member]
12/4/2004 1:26:20 PM
One of my buddies used to fill trash bags with acetylene, tie them off and let the wind push them half way across a lake before he'd shoot it. Big boom, fun to watch.
brasspile  [Team Member]
12/4/2004 1:48:04 PM

Originally Posted By legonas:

Originally Posted By 1Andy2:
Propane tanks do not explode when shot. I know this for a fact.



+1, i have tried on many occasions to find the "perfect" reactive target, and propane isnt it. ive tried .22, 7.62x39, and a long time ago, .270 . not only did they not explode, they didnt even move when hit.

i remember one great experience as a kid was shooting a fridge with a .270 and having a huge trail of flame come out the back exit hole. i never knew why this happened.



Add a roadflare about 6" away from the tank.

Here is a 16oz tank:

BillofRights  [Member]
12/4/2004 2:34:58 PM
Things that are flammable or explosive have a fixed amount of energy that is required to initiate the reaction. As stated, a bullet passing through flammable liquids or gas does not normally impart enough energy. Multiple rounds, big rounds, tracers or nearby flames can result in fire, but it's not as easy as in the movies.



Originally Posted By 1Andy2:
heh reactive target...


I haven't done this, but I've heard that aluminum reacts with Drano giving off Hydrogen gas.
What you could do is take a bottle of drano, put some aluminum foil strips in it, and then cover the neck with a balloon. Once the balloon fills with the Hydrogen, shoot it (from a distance).

Should be pretty reactive.





I am pretty sure that this wouldn't work unless you were shooting flaming arrows, or maybe tracers.




This however, does work, but I'm pretty sure you need to add O2 to the acetylene to make it properly volatile. Problem is, there is a pretty good chance of the the trash bag exploding while you are holding it:

"One of my buddies used to fill trash bags with acetylene, tie them off and let the wind push them half way across a lake before he'd shoot it. Big boom, fun to watch."
Greenhorn  [Member]
12/4/2004 2:40:22 PM
I have a video from Bulletfest of a full propane tank getting shot. It vented with a 6' fountain of mist for about 5 seconds, and then died down to nothing.
PaDanby  [Member]
12/4/2004 9:34:07 PM
To get an open air "explosion" from a hydrocarbon (gasoline, butane, propane, diesel) you need a fuel air mixture of a certain range of ratios of fuel vapors to air (actually the oxygen) and then you need a spark or flame of the proper temperature to ignite the mixture. Many hydrocarbons are gaseous at standard room temperatures and pressures but are a liquid when compressed into tanks. Your stove/lantern operates of the vapors evaporating off the liquid surface.

So when you poke a hole in the tank the liquid fuel coming out is too fuel rich before it evaporates, at some point you may get the right ratio, and if "lucky" or skilled, you have an ignitor at that point to set it off. If you have a very small point where the fuel air mixture is you might just get flame, because there isn't enough heat to sustain or generate enough vapor to explode, but maybe enough to keep evaporating a vapor layer that mixes with air to burn.

With the refrigerator, the refrigerant operates at a vapor pressure that it probably formed a sufficient vapor concentration at some point where you got a spark of the steel.
clutchsmoke  [Member]
12/4/2004 9:46:03 PM
As mentioned before,propane cylnders usally need a outside source of flame to ignite them. A friend had some starburst .308 rounds that throw sparks on impact, Lit the propane everytime. As for the refrigerator, Refrigerant gas is not flamable but the oil in the system is. Refrigerators when punctured tend to spray out a mist of refrigeration oil with the refrigerant gas. This kinda gives it a flamethrower effect when lit. Had it happen a few times while brazing with a torch. By the way, if refirgerant gas is burned it makes phosgene gas which was used in ww1 as a nerve gas.
mtechgunman  [Team Member]
12/4/2004 9:50:23 PM
What is your definition of "blow up"?


If you shoot a propane tank, it will not go into a huge ball of fire and leave a crater this size of a football field in its tracks.

however, it will "explode". No flames, but the fact that the tank has comressed propane inside of it, and the rapid exiting of the propane, can cause quite the show.


i have heard that if you set a lit flare on the backside of a tank, then you will get a fireball, but i don't know for sure.


EDIT: The propane tank that i say "explode", actually had about 2/3 of the back side ripped out.
Tango7  [Member]
12/5/2004 1:49:30 AM
The reason cars blow up when they catch on fire / get shot in hollywood is

1) 5lbs of black powder / napthalene crystals in a heavy duct taped carboard mortar tube, with an electric detonator

2) (2) sticks of C4 (or equivalent) with aforementioned detonator, usually placed under the front of the rear seat.

Depends on whether they want a "TV" explosion (#1 - lots more smoke) or a "realistic" one (#2).

Same things with propane cylinders and such - they "mod" 'em for movie shots.
The_Neutral_Observer  [Team Member]
12/5/2004 1:55:48 AM
The Neutral Observer has experimented on propane tanks before.

They won't explode with regular rounds.

They do spin around in a big cloud of white gas, and the little ones will shoot off into the air like rockets.

Tracers will light them up everytime.

If you put a candle next to it and then shoot it, that will work a good bit of the time (if the candle doesn't go out).

Really, you can't get things to blow up with regular rounds. The Neutral Observer has heard of steel core ammo sparking and setting brush fires at outdoor ranges. Tracers will ignite some things, but it's by no means a sure thing.
SFR  [Member]
12/5/2004 1:56:43 AM
this thread needs more pics!
nascar3n8fan  [Member]
12/5/2004 2:07:53 AM

Originally Posted By thelastgunslinger:
Somethings blow up when you shoot then because they are filled with Tannerite.




I've noticed that trend as well. Funny how that works.

Damn I love reactive targets.
ALPHAGHOST  [Member]
12/5/2004 2:15:46 AM
oh i thought that you ment stuff like glocks


they do casue of high heat, i guess

try shooting cans of ether-- a friend of mine says its nice
71-Hour_Achmed  [Member]
12/5/2004 6:09:55 AM

Originally Posted By 1Andy2:
I haven't done this, but I've heard that aluminum reacts with Drano giving off Hydrogen gas.
What you could do is take a bottle of drano, put some aluminum foil strips in it, and then cover the neck with a balloon. Once the balloon fills with the Hydrogen, shoot it (from a distance).


The sodium hydroxide and aluminum reaction throws off a LOT of steam as well. You can burn the hydrogen gas, but need some air in there as well to do it properly.
RyJones  [Team Member]
12/5/2004 6:22:48 AM
It took Joe and I over a year to get fireballs working for the shoot, and they weren't 100%.

If you want reactive targets, come to the shoot or buy some tannerite.

Everything else is hollywood.
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