gas explosions - Archive file

[megalomania]

rjche
Frequent Poster
Posts: 52
From:
Registered: SEP 2000
posted September 21, 2000 07:36 PM
--------------------------------------------------------------------------------
A techinque used in behind the lines warfare to remove things like buildings, streets with sewer tunnels, etc, was use of gas explosives. They can do a good job on removing isolated old buildings, but they will scatter stuff over a sizeable distance.
These are simple, not critical as to mix ratio, and easily obtained everywhere.

They use air as the oxidizer. Air weighs about 8 lbs per 100 cubic feet.

Almost all easily gotten fuels use a 1 to 15 ratio by weight, in air. They have to be volatile to use, or something like propane.

acetylene is more violent but propane is more powerful.

Acetylene is also explosive in an enormously wide range of ratios because it's about to explode itself at room temps. Above 15 psi gage, (30 psi absolute) it can decompose with violence. That's why the pressure gage on acetylene tanks is red-lined above 15.

Thus a building 10x10x10 contains 1000 ft3 of air.

That container holds 10x 8 or 80 lbs of air.

At the normal carbueretor ratio for cars of 1 lb gasoline to 15 lbs air, you would need about 6% of 80 lbs for the gasoline wt.

That's about 5 lbs round numbers.
Gasoline weighs about 5 lbs per gallon, so
the thing comes out to 1 gallon gasoline for each 1000 cu ft of air. Easy to remember.

Using propane the ratio is about the same on a weight basis, but propane weighs about 4 lbs per gallon, if you measure it that way. It usually comes in 20 lb tanks.

In many areas it is illegal for non licensed persons to transport larger tanks than the 20 lb sizes. This size is available everywhere because barbeque pits use them, as do some camping trailers.

Gasoline and propane develop about 30 psi blast pressure in air at 1:15 mixes. The pressure goes up a lot in car cylinders because the gas/air mix is compressed about 10 times and then lit, so the peak blast pressure approaches about 900 psi. If timing is to early, the mix will detonate, and the pressure briefly goes to thousands of psi, and can break piston rings etc.

But back to the use of these things for demolitions. Few buildings can stand much more than 3 psi internal pressure. Some hardened ones can stand 5, but 30 is way above anything you are likely to encounter.
Some blast shelters can take outside pressure but not internal pressure very well.

Calculate the force on a door with 30 psi on it for an exercise and an education.

Ground cannot resist more than about 15 psi. gas explosions in mines do not usually destroy the tunnels because they are in rock, but in sewers large enough to stand up in, they will dig up the whole street and lay the dirt on top of the cars parked along the sidewalks.

That is why some cities forbid dumping gasoline or solvents down the toilet or sink.

The mixture does not have to be in the whole building. Just one or a few inner rooms mixed properly can wreck the whole thing because of the excess pressure.

This 30 psi is what makes the tennis ball guns seem so energetic.

Propane can be used through a very long small tubing, available everywhere. It can be injected slowly, then when done, and after time is allowed for the air to mix properly it can be ignited via the same tubing by pumping salt water into it to the far end. Then use a stun gun with one probe grounded to spark your end, and a spark will appear at the other end, to ignite the mixture.

Or any remote flame source like a tracer can do it also.

This information is for educational purposes only. Doing this in a non wartime environment would be considered a serious crime. However you may one day find yourself behind enemy lines if things keep deteriorating. Then you may have to defend your homeland. The knowledge would then be lawful to use, and indeed the over-run government may give you a medal later for your effort in driving out the enemy.

Some spec troops had a little card, and they would pace off the outside of a building, or use a photo to gage its volume, and the card would give the best mixes for gasoline, acetone, laquer thinner, naptha, propane, natural gas, butane, etc. whatever was stored nearby, or inside, and could be used.

The problem was measuring the gasses, but large errors were tolerated though with good results.

Most every pyro knows about acetlylene/oxygen, which goes directly into detonation, at normal atmospheric pressures.

As mentioned elsewhere, propane oxygen in pressure ratio 100 psi propane then add o2 till pressure reaches 300 will detonate crude an fertilizer in a tank that can stant the 300 final psi.

It is fired by a glow plug in the tank, but the mix must sit a couple hours for the gasses to mix well.

If the filler line (1/8 inch metal tubing or less, has a valve on it, after injecting the oxygen, wait a couple hours and let a tiny amount out to clear the o2 from the line.

Catch a little in a container, (baloon, condom,) and shut the valve.

Light the container, and if it puffs, you can set the whole thing of by lighting the gas allowed to slowly exit the cracked valve. If the flow is not to great, the flame will go through the valve and down the pipe to the container, and fire it all.

This is tricky and only needed in an emergency when nothing else is available.

A propane tank can take 300 psi, if you seal up its pop off valve. Do test it with water pressure before using this however.

If you test it with air pressure, stay safe distance for if it busts you can be seriously hurt.

An auto sparkplug can be put into the tank, but its gap must be set only about .01 inches or you will not be able to spark it easily. With a stun gun or neon 15 kv transformer, you can spark one with gap up to about .025.

Gas explosions using propane have been used to run moles out of their tunnels when they get to be a major pest. Acetylene also works well for that.

These have been used also in hunting animals in burrows, but is illegal in normal times.
It could provide food in an emergency though.

Knowledge is power. Power is sometimes necessary to repulse unlawful power used against you, and to protect your rights and property. Therefore, like food, you need some "stored" although you have no need for it today.


ezekiel
Frequent Poster
Posts: 110
From:
Registered: SEP 2000
posted September 24, 2000 10:32 AM
--------------------------------------------------------------------------------
Interesting post.
However i'm not convinced about acetylene detonating when in contact with oxygen...
I know of a "bomb" that involves acetylene, it would not work if acetylene instantly combusted.
Also if it did spontaniously combust then oxy-actylene welding torches would not need a sparker to light them.
I found some figures for maximum and minimum parts of gas for explosion(or combustion) to occur...

Gase's (% by volume) Lower Limit Upper LimitWater gas (C + H2O) 7.0 72 Natural gas 4.7 15Hydrogen 4.0 75Acetylene 2.5 81Propane 2.2 10Butane 1.9 9

Ignition depends on method of initiation, uniformity of mixture, and physical conditions.

------------------
Ezekiel

'Things bad begun make strong themselves by ill'


ALENGOSVIG1
Moderator
Posts: 766
From: Vancouver, Canada
Registered: NOV 2000
posted January 22, 2001 08:54 PM
--------------------------------------------------------------------------------
So, if you were using gasoline, would you just dump the fuel on the ground and wait? or could you atomize it with a pesticide sprayer or something?
------------------
Explosives Archive


MacCleod
Frequent Poster
Posts: 215
From:
Registered: DEC 2000
posted January 22, 2001 10:11 PM
--------------------------------------------------------------------------------
ezekiel,I think he meant that acetylene/oxygen when ignited,detonates easily (as in a room full of),not spontaneously combusts on contact(?).
------------------
"That which does not kill us,makes us stronger"


endotherm
Frequent Poster
Posts: 164
From: dunno
Registered: JAN 2001
posted January 23, 2001 07:04 PM
--------------------------------------------------------------------------------
Theoretically then, a way to get pressures above 10,000 psi,would be to ignite a high explosive into gasoline. When the high explosive detonated and lit the gasoline, the gasoline would be being atomized at the speed of the explosion adding both pressures together would result in an enormous amount of pressure, right?


ALENGOSVIG1
Moderator
Posts: 766
From: Vancouver, Canada
Registered: NOV 2000
posted January 23, 2001 07:08 PM
--------------------------------------------------------------------------------
how is the HE gonna ignite the petrol? It would be next to impossible. Not to mention the HE would suck all of the oxygen out of the area
------------------
Explosives Archive


CragHack
Frequent Poster
Posts: 606
From:
Registered: DEC 2000
posted January 23, 2001 07:17 PM
--------------------------------------------------------------------------------
oh yeah, i have had REALLY small charges of AP put out pools of gas. it is cool to watch.
------------------
...Æ


endotherm
Frequent Poster
Posts: 164
From: dunno
Registered: JAN 2001
posted January 23, 2001 07:24 PM
--------------------------------------------------------------------------------
ok,you say it can put out pools of gas, but i was not talking about putting out pulls of gas, i was talking about instantly atomizing a large amount of gas by a small high explosive charge, the optimal ratio would be one that the amount of air being pushed out by the explosive, is the same as the tank of gasoline, and possibley a small amount of large chunks of thermite or red phosphorus would be good to send out burning chunks of material, to insure ignition, but you were correct, i did not specift this in my previous posts


ALENGOSVIG1
Moderator
Posts: 766
From: Vancouver, Canada
Registered: NOV 2000
posted January 23, 2001 07:30 PM
--------------------------------------------------------------------------------
it would probally just burn without exploding really because of lack of oxygen!
------------------
Explosives Archive


Anthony
Moderator
Posts: 2312
From: England
Registered: SEP 2000
posted January 23, 2001 07:41 PM
--------------------------------------------------------------------------------
Now you're describing an FAE not a gas explosion!


Mr Cool
Frequent Poster
Posts: 991
From: None of your bloody business!
Registered: DEC 2000
posted January 24, 2001 03:21 PM
--------------------------------------------------------------------------------
Get a canister of liquid oxygen holding a known weight of gas (or rather, liquid), and put a shaped charge along its lenght to split it nicely. Attatch a detonator and put it in the optimal weight of petrol. When the shaped charge is detonated, it'll split the O2 canister along its length, releasing all the gas almost instantly. This, along with the blast from the detonation, will atomise the petrol in the O2, forming a compressed, zero oxygen balance fuel/oxygen mixture. Remember that per gram, petrol contains something like five times the energy of TNT. It'd be ignited instantly by the HE (especially if a few % of Al powder is added to the HE in the shaped charge to raise the det. temp.), and would be INCREDIBLY powerful for it's size.
Now THAT would be fun to watch!!!
On a slightly less destructive note, small bottles (250ml) 2/3rds full of hydrogen, 1/3rd full of oxygen with a fuse sealed into the lid make excellent projectiles from a pneumatic spud gun if they're made a bit heavier by attatching weights to the front. And I don't think that is classed as making explosives by the law, but I might be wrong.


Mr Cool
Frequent Poster
Posts: 991
From: None of your bloody business!
Registered: DEC 2000
posted January 27, 2001 09:12 AM
--------------------------------------------------------------------------------
Something else I've just tried quite successfully: Using propane/oxygen in a 500ml coke bottle at 2 atmospheres of pressure as a propellant in a sort of mortar. It had a fuse in the lid, and the launch tube was some PVC which fitted over the bottle quite nicely, with an endcap and a small hole for the fuse. The bottom of the bottle was scored to make it split evenly. I dropped the bottle down the tube, so that the fuse came out of the hole in the endcap. The projectile was a cast piece of the resin used for fibreglassing surfboards, with a hollow cavity in the middle. An ignitor was attached to the fuse, and the tube was buried in the ground. When I set off the ignitor, there were 5 seconds (2" of fuse) before it went off. The projectile went straight up and out of sight.
Next I'm going to try to launch another fuel/oxygen bomb from the mortar, instead of the resin. I didn't check the condition of the launch tube afterwards, so I might need a new one!


Mick
Frequent Poster
Posts: 229
From:
Registered: OCT 2000
posted January 27, 2001 09:19 AM
--------------------------------------------------------------------------------
the smarter idea, if you are looking for a pretty dam big explosion
is to detonate a BBQ gas cylinder(20kg size).

stuff mixxing propane freely with air...

altho you would get a pretty dam big blast..
you will get a bigger one detonating a BBQ cylinmder...


Anthony
Moderator
Posts: 2312
From: England
Registered: SEP 2000
posted January 27, 2001 03:54 PM
--------------------------------------------------------------------------------
How did you pressurise the bottle with the gases?


Mr Cool
Frequent Poster
Posts: 991
From: None of your bloody business!
Registered: DEC 2000
posted February 02, 2001 06:20 PM
--------------------------------------------------------------------------------
Filled the bottle with water, bubbled in 168ml of propane, bubbled oxygen in until it was full. Then, I took the bottle out of the bowl of water that it was in, and screwed the lid on. The lid had a valve and a threaded tube glued into it, which I could attatch to my little oxygen cylinder, which has a built-in pressure guage that measures the pressure in the outlet pipe. Then I just let in oxygen until the guage said 2 atm.


Anthony
Moderator
Posts: 2312
From: England
Registered: SEP 2000
posted February 03, 2001 04:28 PM
--------------------------------------------------------------------------------
I thoght that would have been a bit expensive, requiring a vlave for each charge. I suppose 1atm would still produce a decent bang and you wouldn't need to go the bother of pressurising it? You wouldn't even need bottled O2 either, just a reaction that produces O2. I will try it.


SofaKing
Frequent Poster
Posts: 392
From: YEAH RIGHT !!
Registered: SEP 2000
posted February 04, 2001 12:43 PM
--------------------------------------------------------------------------------
A while ago I thought that a gas explostion could be produced using the reaction between H2O2 and MnO2 to produce oxygen and NaOH and Al to produce hydrogen. Some Al foil,powdered MnO2,and powdered NaOH would be put in the bottle. Then to activate H2O2 solution would be poured in and the reaction would take place. A simple fuse or e-match would be glued into the bottle cap. The problem would be the reaction is very exothermic and the bottle might melt.
------------------
"ARE YOUR PAPERS IN ORDER" -- Jack Booted Thug


Mr Cool
Frequent Poster
Posts: 991
From: None of your bloody business!
Registered: DEC 2000
posted February 05, 2001 01:27 PM
--------------------------------------------------------------------------------
The valve is a bicycle tire valve. They only cost about 30p, and the increase in pressure makes it significantly more powerful, because you have twice the energy stored in the gas and the same amount of energy is released in half the time.
1 atm is still fun, but do use oxygen. If you use air, the propane/O2 is so dilute that it doesn't explode, it just acts like a little rocket and shoots a few feet because all the gas rushes out the fuse hole.


Anthony
Moderator
Posts: 2312
From: England
Registered: SEP 2000
posted February 05, 2001 05:56 PM
--------------------------------------------------------------------------------
Thanks, will try soon.


Ctrl_C
Frequent Poster
Posts: 230
From:
Registered: NOV 2000
posted February 06, 2001 04:21 PM
--------------------------------------------------------------------------------
just my $0.02: acetylene + oxygen in balloon makes one hell of a loud boom...it echos off the valleys around my house 5 times.
speaking of, in chem today we were doing combustion rxn's (wow that class is boring...maybe i'll apply to teach it) and the teacher said

"what does c2h2 + o2 = ?"

i replied

"a three foot crater in the snow in my yard"

he just kinda looked at me funny....i love when people fear me.....muwahahaha

[Ropik]

When speaking about BBC cylinders, what about the big tanks used by houses without pipeline for gas? Everyone saw(for sure) what can do one exploding cylinder of propane to building, so this tank should do extremely extensive damage to anything in vicinity... Many potential target for demolitions have these tanks. I bet that gas tank is much more easily cut than normal building. My question: what is the best charge to perforate the tank and ignite the contents? Ribbon charge around entire circumference? Shaped charge to just pierce the wall? Blast off the filling valve? Something like POL thermate/explosive external charge? Using one normal propane(or acetylene) cylinder with ribbon charge to blast off the tank? Thanks.

EDIT: I thought about the FAE effect described in Anarchist arsenal and several other books, rather than incinerating everybody close enough with burning gas vapors
NBK, are you sure that simply igniting the vapors will bring this effect? I would think that you must detonate the cloud with some additional charge.

[nbk2000]

I'd say a circular cutting charge on the underside of the tank, so that, when detonated, the liquified gas will be ejected straight down and spread out as a ground hugging cloud of cold vapors, rather than being ejected up into the air where'd it'd only make a pretty fireball, rather than an incinerating cloud of flaming death.

Be sure to including plenty of ignition sources around the perimeter of the target area to ensure ignition.

[Anthony]

Imagine disabling the safety valves and setting a large fire around one of those things! It'd take quite a while to heat the tank to exploding point though (it does contain about a ton of refridgerant afterall).

Reminds me of some TV footage I once saw of a calor gas bottling plant that caught on fire. Eventually, the main underground storage tank exploded and the fireball engulfed several blocks!

[nuclearattack]

In the past i used to make explode camping propane tank. I did it just for fun with my friends (pyro and dynamite are in my blood!), i used to lite some fuel tablets under the tank. It requires a lot to explode and sometimes the gas doesn't ignite. However the explosion is huge expecially with heavy tanks that can reach a high overpressure in it before explode. With small camping gas tank it takes about 1 minute but with 10l tank gas it can take also 5 minutes! However a good demolition charge under the tank will do a good job for sure, some bengala sticks around the tank will do the rest to ignite the gas. Maybe that using a thermobaric charge will ignite automatically the gas due to the high temperature reached?

[Ropik]

Yes, that's the way primitive propane bombs are made: One would take two bottles of the gas, screw the gas cooker on one of them, then put the second cylinder in the flame. Several minutes and off it go.
Anthony, I'm thinking more along lines of explosives, because large fire under this huge tank near anything valuable will immediatelly attract firefighters, police and other pesky people(I am thinking about possibility of demolition using these tanks in war time or something similar, not in crime), they will smother it and that's it. But... maybe... when you would use something like pyrogel(napalm + asphalt + Mg + several variations of oxidizers and such), they probably wouldn't have enough time.
Recently, I saw one of these tanks 20 meters from gas station. The station is closed at night, so when you lit the napalm fire at midnight... I doubt that the station would get some mercy:).

[nbk2000]

When a tank is heated so much that the pressure of the boiling liquid within causes it to rupture, that's called a 'Bleve' (Boiling Liquid Expanding Vapor Explosion).

They're quite dramatic. :)

This is what a 65 ton propane rail-road tanker car explosion looks like. Notice the water tower in the foreground for scale. ;)

http://odin.dep.no/archive/mupbilder/02/123/f0901015.jpg

And an aerial view.

http://www-pors.hit.no/tf/fag/i4695/indexn1.jpg

Looks like a tactical nuke strike, doesn't it? :D

Google reveals a wealth of factors that increase the probability of a successful BLEVE event.

[Ropik]

In the first place, thanks NBK for the idea of googling. Maybe I am very dumb - I didn't figured this source out myself :rolleyes: .
Second thing is that I didn't think that so short time is needed to make a BLEVE. This table (http://me.queensu.ca/people/birk/research/thermalHazards/bleve/images/ttofail.gif) shows that as little as ten minutes can be enough - even for a large tank :eek: . Thats data for accidental fires... Some really good incendiary around and under the tank("engulfing fire" in the above table) should speed the process up further. Another found information was:
- Strong tanks are less prone to BLEVEs (Why?? :rolleyes: )
- High pressure relief valve (PRV) set-pressures increase both the risk and the hazards of a BLEVE
- If a tank fails when the liquid level is high and the liquid is uniformly heated to the PRV set conditions, the chance of a BLEVE is highest and the resulting hazard consequences are greatest
- Blast overpressures from BLEVEs are generally low and the hazards are small compared with those from the fireball and projectiles
- Projectiles from BLEVEs are the furthest reaching hazard (up to thirty times fireball radius)
- The set-pressure and performance of PRVs was found to play an important role in the severity and probability of BLEVEs

Also check out This (http://www.scienceinpublic.com/freshinnovators/2004/colinyoung/colinyoung.htm), according to it there is cheap and quite easy anti-BLEVE solution. Watch out for it, but... anybody seen it?? I'm suspicious that it's just another patent without real applications.

EDIT: Sorry NBK, but this wasn't written as sarcasm - I AM really that dumb.

[nbk2000]

In the first place, thanks NBK for the idea of googling. Maybe I am very dumb - I didn't figured this source out myself :rolleyes:.


Sarcasm is a double-edged sword...it can cut the wielder as well as the target.

That patent idea sounds rather lame. Using the liquid from the bottom to cool the top? Uh, isn't that going to increase the rapidity of the vaporization of the liquified fuel? It is, after all, a closed system, so there's no evaporative cooling effect.

BLEVE's, to date, have been accidental. If BLEVE's were going to be purposefully made, for use as weapons, then the conditions of their deployment could be optimized.

The fireball effect is what would be most devastating, I'd think, especially in the close confines of an urban canyon. I don't know how many kilo-calories/kilo propane gives off when it burns, but it'd be interesting to calculate it and see what the equivalent yeild would be for some of the well-known explosives.

I'm sure the radiant heat effects would be capable of nuke-like damage at some distance, such as non-contact 3rd degree burns, flash-blindness, firestarting, etc.

BLEVE'ing a small tanker of less than a 1,000 gallons capacity, easily drivable through tight city streets, would handily devastate a sizable portion of an urban core.

The problem is getting it hot enough to BLEVE before the fire services can either stop it or evacuate the immediate area.

You know, electricity can substitute for fire, and with none of the attention drawing attributes...

Many multi-KW electric resistance heating elements inside the tank, connected to a high-amperage power source such as the feed into an office building, would be sufficient for the task.

Once the fuel was sufficiently heated, explosives rip the tank apart and incendiary elements ignite the fuel vapor in a highly efficient manner.

Claymores and other deterrents would be emplaced to protect the BLEVE device from possible detection/tampering/removal during the requisite heat-up phase, but would not be activated unless the device was being tampered with or approached.

The problem with a fuel explosion in the open air is that, once ignited, the rising fireball acts as a convection engine, pulling the burning fuel BACKWARDS, towards the center, rather than expanding it OUTWARDS, where it could cause further damage.

Finding proper structural confinement would help to push the fireball outwards, especially if there was any kind of overhead cover to prevent the rising fireball.

[Anthony]

I can see the theory behind that patent: The top of the tank is kept cool (and thus maintains integrity) until all the gas has escaped via the pressure release valve.

Since in an intentional BLEVE, any PRVs would be disabled, it's a moot point :)

The chance of a BLEVE occuring if there is no PRV is pretty much 100%

Perhaps and underground car park below a high rise office building would provide good confinement? Or would there be problems with lack of oxygen?

Liquified propane has an energy density of about 25MJ/litre.

The 1000gal tank example would contain roughly 25MJ x 3.8 (gals) x 1000 = 95 000MJ or 95 giga-joules!

The density of liquid propane is 0.58, so that 1000gal would weigh 3800 x 2.204 metric tons.

Latent heat of vapourisation is 425kj/kg. So to vapourise the entire tank would require 425kj x 2204kg = 936700kj or 937MJ

Which is 260Kwh

If your heaters ran from an industrial 415v feed, at 100A that would be 41.5kwh, so would require about 6 1/4 hours to vapourise the entire tank.

Although, I have no idea if the tank would hold up to that, it'd probably explode in much less time.

[nbk2000]

A car parking structure is exactly what I was thinking. :)

Although an above-ground one would be better, as the fireball would radiate out into the surrounding streets as an expanding ring (seeing chessy 'ring-o-doom' effect from 'remastered' Death Star explosion :rolleyes: ), thanks to the overhead cover provided by the structure, rather than be confined within a building, as it would if it was an underground garage.

An intact building full of charred corpses doesn't visually inspire fear like the scene of a demolished city center, complete with smoking corpses and burning rubble does. Think Bogata bombing here.

The tanks contents wouldn't have to entirely vaporized prior to the BLEVE, as long as a sizeable portion of it was, because that would provide enough heat to vaporize the remaining liquid with mimimal loss of energy.

And, of course, the tank could possibly be reinforced to be extra-strong, making the release all that more sudden.

BTW, how many kilos/pounds of NG or TNT would it take to equal 95GigaJ of energy?

[Anthony]

The specific combustion energy of TNT is 4.6 MJ/kg

So: 95 000MJ / 4.6 = 20 652kg

20 tons!

Obviously the blast effect wouldn't be the same, as burning a load of lard would release more energy per unit mass. Few people can get ton quantities of TNT though, but anyone can get propane.

There'll be some awesome heat coming from this thing though! Like you say, nuke-like radiant heat effects.

Knowing that an explosion occured in a crowded city centre that released the energy of 20T of TNT, looked like a nuke, felt like a nuke should give the media plenty of material :)

[nbk2000]

Throw some 'dirt' ;) in with it for that lovely glow-in-the-dark effect and you could blog it into having been a backpack nuke that fizzled. :D

The more the government denies it, the more credence they give it, as why would they say it wasn't a nuke when everybody saw the fireball, the nuke-like effects and, most telling, the radiation?

Conspiracy theorists will keep the myth alive forever, just like JFK and the 'magic' bullet. :rolleyes:

It'd be enough to get the fear-juice flowing, which is what terrorism is all about, not body counts.

[nuclearattack]

To Ropik:
i think that when it's said "strong tanks are less prone to bleve" it's referred to the fact that a lot of more energy and heat is required to make a bleve.
I'm thinking about methane tanks...my car is double powered so it has 2 methane tanks very strong. The methane is pumped in those tanks at 250 atmospheres but they are able to resist at 300 atm and more. Those tanks are 1,5 cm thick!
A very nice bleve! But for the moment i can't buy a new car!
They should give a good bleve also without heat, just only a shaped charge and the natural high pressure of this tanks will do a nice job.

[Anthony]

A strong tank is more likely to hold the pressure while the PRV vents the tank.

In most BLEVE situations, the tank is heated, the gas pressure inside rises untill the PRV opens and starts venting the tank. From there it'd be a race between how fast the liquid propane boils, creating pressue, and how fast the PRV can vent it. If the PRV can't keep up, the gas pressue will overcome the tensile strength of the (weakened by heat) tank. Obviously a stronger tank will hold more pressue, and the higher the pressure, the faster gas will escape through the PRV.

I suppose that technically a high pressure methane tank wouldn't BLEVE, as there is no liquid to boil. I'm sure the effect would be much the same though :)

[Myrol]

Yesterday, I have seen a film about Science for example is it better to be Fat or Thin in the daily life (the Thin Guy won the match, becaue there just some pro's where the Fat Guy could bet with, cold weather F.E.). There was also a GREAT test how "unbreakable" some thinbgs are. Well, they smashed things like Sodacans, household Dewars, drinking glasses cups and so on. The drinking glasses were amazing, a massive Baseball Bat made of V4A Steel!!! couldn't crack the glasses, a Wooden one of course not!

So they have done the spectacular way: A small Caravan was filled with all these things and prepared with two big Balloons 1,5m Diameter filled with stochio Propane Oxygen at 5Bar. The Ballons hold the pressure because they were very strong. BAAAAM, they fired the Gas and it blew the trailer into baby-sized pieces thrown over 200m away. The Guy searched after some things, and unbelieveable THE FUCKING GLASSES DIDN't BROKE :eek: :eek:

I cant fucking believe that. This mix is very powerful and it was pre-compressed so you get some extra strenght because there was more Gas in the Ballons as with 1Bar ordinary. The Detonation looked similar to 2kg ANNM. Holy Shit........

[nuclearattack]

Ah! I love these kind of movies!
There is one thing that i didn't understand: why a baseball bat is not able to crack a drinking glass? :confused:
If you let fall a drinking glass it will break in pieces...i'm confused!
Can you explain it to me? :(

[Myrol]

It's very Easy: The Drinking Glasses were made of Poly carbonate a nicely hard plastic made with a synthesis wich needs pure Phosgene!!!! Its the same thing like in the Ruhrgebiet, theres a Factory where you can see around 1m of an absolutely translucent pipe......its crazy but through this 30cm thick pipe goes liquid HYDROGEN CYANIDE in amounts to kill towns instanteus :eek: :eek: :eek: :eek: Back on topic: I made some calculations about the Detonation pressures for some Gasmixes. Hee are the results:

Hydrogen:Oxygen 6:1 101,4Bar
Hydrogen:Oxygen 2:1 106,9Bar
Propane: Oxygen stochiometric 132,7Bar
Butane: Oxygen stochio 190Bar
Ethylene: Oxygen stochio 202,6Bar
Acetylen: Oxygen 1:1 276Bar!!!

Well, you can see obvious the winner. The mix with Hydrogen is somewhat curios for me......umm, doesn't matter....Butane and Oxygen seems to be really powerful.....shall try that :D I think, the Pressure for the stochiometric mix of Acetylene and Oxygen should be even higher as this one but I'm lacking the VoD for that mix....if someone can help, please!
P.s. The FAE-mix Oxirane Air has a preessure of around 19Bar.....ordinary Gasoline well mixed in Air just 10Bar......imagine what happens in Oxygen :D :D

[ProdigyChild]

Rather than heating the tank by electricity, I'd over-fill it with compressed air until it ruptures. That should be possible with normal electricity power withing a reasonable amount of time.

Or even, if someone arrived with a truck + high pressure oxygen tank and filled in some of that.....
The reaction should yield enough energy to rupture the tank. Starting combustion requires some work, though.

Filling would require some tools. Something you can weld onto the surface of the propane tank and then drill a hole (protected by pressure), then put oxygen in.
There are welding methods, that allow such, really!
Do I have to draw a sketch?

[nuclearattack]

Oh! Polycarbonate it's really resistant. Bullet proof glass is made with polycarbonate and also anti riot shields are made with this plastic.
However i'm impressed that it has resisted to the gas explosion, not only for the overpressure but also for the temperature involved.
This winter i want to make some tests with gas explosions just to have some fun and to make some nice movies.

[FUTI]

to nuclearattack: I saw a rocket exhaust cover made of CaCO3 strengthened polycarbonate so I guess it can withstand high temperatures.

to Myrol: Nice work with that calculation you have helped me a lot and answered some of mine question.

[Anthony]

These polycarb drinking glasses are pretty off topic. I'm not surprised they didn't break in the gass explosion, why would they? They're not brittle enough to fracture from the shockwave, and because it's an open container, the over-pressure won't affect it.

Back on topic:

You don't necessarilly have to go to the trouble of welding a fill-port into the propane tank whilst it's full. You could modify an empty one, and then fill it.

The trouble with filling the propane tank with compressed air to rupture it, is that a BLEVE will not occur. For a BLEVE, the liquid propane must be heated to boiling point. Electricity is also silent, whilst people might notice a large, noisy compressor running.

Filling the tank with a stoichiometric amount of oxygen would yield an impressive explosion. But enough oxygen to fill a 1000 gallon tank might be expensive, and it more complicated than a normal BLEVE.

[ProdigyChild]

Does 'Bleve' neccessarily mean, that **ALL** liquid would go into gaseous state if the container was opened (=pressure set to 1atmosphere)? I can hardly believe that!
If you open a fire extinguisher, the (over-heated) CO2 partially turns into snow from the cooling effect of the part that really turns into gas.

My gut feeling tells me, that such effect (quantitive vapourization) would only occur at pressures similar to the ones you have for gases that can't be liqified by pressure at normal temperature. Like nitrogen. 200bar to get a useful specific gravity. A half filled propane tank has perhaps 0.4g/cm3 average density. This density as a result of compressed gaseous propane??? No, beyond my imagination.
Not one single propane tank would stand that! They don't have a few inches wall thickness, do they??

Given, that was true. Then the rupturing tank would alread cause a terrible shock wave of a hundred bar in the vicinity of the container, flattening houses and trees...

So it can only be some portion of the propane that turns into gas. Much of the liquid is simply scattered around and evaporates upon contact with warm surrounding objects.

Correct me, if I'm wrong.

[Boomer]

I guess you can calculate the percentage that instantly vaporizes!

I have no values at hand for propane, but for comparison water will do: It takes approx. 2500 kJ to evaporate a litre of water, while it takes 4.2 kJ to heat it one degree. Since the energy to gasify it must come from the heat it already possesses, it would take 2500/4.2 = 595C above boiling point = 695C!

Water has a higher specific energy, but also needs more heat to evaporate. If this equals out somehow, you are probably right that not all turns to gas instantly. But a second later there is so much energy from the flames that the rest will follow anyway.

[Anthony]

If you heated that CO2 fire extinguisher till it exploded (saftey valve disabled), then you wouldn't get any "snow" (dry ice)!

Yes, there will probably still be liquid propane in the tank when it explodes, but I believe that it will be like super-heated water at this point, and flash to vapour once the pressure drops.

Afterall, BLEVE = Boiling Liquid Expanding Vapour Explosion :)

[akinrog]

As for bleve, some idea came up my mind following the NBK's idea. Instead of using heating elements, what about using (a few) microwave magnetrons to superheat the fuel in the tank.

In this manner it might be possible to eliminate visible glow of a electric heating element. I believe microwave can (super)heat and thereby pressurize the fuel in the tank. Can this work?

[nbk2000]

http://www.dcfp.navy.mil/mc/video/truckfire.mpe

The explosion of an LPG tanker truck in germany.

2Mb download.

(Note: the URL is exactly as it should be, don't add a 'g' to the '.mpe')

[rick6]

The BLEVE video is truely a beautiful thing.

I can't help but wonder though if it would be much more effective to load a tank of propane into a cargo truck, drive it to the heavily populated urban area of choise and atomize the cargo with HE.

Maybe back it up with an incindiary just for good measure (assuming war time conditions -of course).

[c.Tech]

Another BLEVE video can be seen here (http://www.fugly.com/videos/3489/tanker_explodes.html).

Instead of the propane tanks you have been taking about, this time it’s styrene which rains molten toxic styrene on people :D.

Gives me some ideas of dispersing chemical weapons, or TIM’s (read the TIM thread under battlefield chemistry).

[OneWhiteNation]

I myseLf am very interested in the concept of gas explosions. Mainly that of the forementioned propane. Unfortunetly my technical knowledge on "shaped charges" is poor and lighting a giant fire under the tank would attract unwanted attention. So how could one get one of these things to go off immediatly?

Unfortunelty do not have access to compressed air either, so overfilling it, would not work either.

I know it can't be that hard considering the two teenage colombine kids made two of them out of 20 gallon tanks, neither went off due to faulty wiring though. Anyone know how they did it? Ive been checking the web for any designs on a propane bomb or even any information on how the duo made thiers, but to no substantial end.

Yes, that's the way primitive propane bombs are made: One would take two bottles of the gas, screw the gas cooker on one of them, then put the second cylinder in the flame. Several minutes and off it go.

Could you go into more depth? I think one of the colombine reports I read said something about a can of gas taped to one of the bombs. I don't understand how you mean it in your text though.

And how can one disable the pressure release valve on a standard 20 gallon propane tank?

[OneWhiteNation]

OK, no one gonna aid me in my pursuit of knowledge? Fine!

I was also thinking about using a 12 gauge armor piercing round affixed to the cylinder to puncture the tank and simeltaneously igniting a few model rocket engines. [Also affixed to the cylinder with the flame ends pointing inward toward where the round is to puncture the tank] Any thoughts? Would this work or would the rapid release of the gas extinguish the flames form the model rocket engines? Would this even explode, or would it simply create a very far-shooting flamethrower?

The model rocket engines could be set off remotely easily enough or even simply with a time delay circuit, but how could one get the 12 gauge round be set to go off remotley and simeltaneously?

[Chaosmark]

Since you seem to think you're above reading the Rules, you get to sit through my lovely rant before getting to the information I've included. We absolutely hate people who don't read the rules. You have absolutely NO EXCUSE either, because at the top of the newbie reply page is a huge lengthy text telling you to READ THE RULES! They're there to keep you from making moronic mistakes like the ones you've already made: first post(s!) outside the Water Cooler, requesting information without contributing ANYTHING to the Forum, and then getting mad when we don't respond to your (spoonfeeding) request within 2 days. Sit down, shut up, and UTFSE.

About the engines
Why would you even want to bother with the model rocket engines? I can see no point in doing so. At best, the rocket engines would ignite and spin around in a circle doing jack, and the tank blows up, spreading said engines around a bit if it doesn't incinerate them. At worst, nothing goes off and the jury gets to laugh at pictures of a propane tank with model rocket engines attached.

Tips
Why don't you either A) UTFSE to improve your technical knowledge of shaped charges or B) think up your own method of setting one off, actually test it, and then post it up for all of us to see and use?

Or you could even rely on C) this link that I happened to find within about 20 seconds of searching the Forum (http://www.roguesci.org/theforum/pyrotechnics/4297-propane-cylinder-high-flow-discharge-unit.html?highlight=propane+tank).

[festergrump]

OneWhiteNation,

You're in the right place (RS.org) and you seem to have a pretty good grasp on the English language, so don't ruin the little bit you do have going for you with a common 14 year old's insistancy on answers to lame questions, ok?

You've been here a week. What threads have you read so far, besides maybe... parts of this one? All those things you didn't understand from the previous half of this thread could be searched and understood more completely before you opt to play 'whack-a-mole' with NBK...

Recommended thread reading within the RS Forum would be:

The Beast has Fed Upon... (Water Cooler)
Sticky: NEWBIES! The Forums' unwritten rules...written down. (Water Cooler)
Banned For Life! (Entire Section)

That should hold your seemingly short attention span long enough for me to pop myself some microwave popcorn and see your name appear in the first mentioned thread, I should think at the very least. [pop... pop...]

Remember always one thing: When someone says to you to think outside the box, they are already assuming you have thought within the box first. I'll leave you to figure out what I might mean by that. (if you read on some, you'll know! Somehow I feel I talk to the wind, though).

[nbk2000]

OK, no one gonna aid me in my pursuit of knowledge? Fine!


See, I give a guy a chance, and he proceeds to fuck it off by going "Fine! I didn't need YOU anyways!".

:rolleyes:

In that case, why even bother posting here in the first place?

From his username, I'm assuming he's a white seperatist, which I have no problem with.

But when you act like a wigger, it makes me embarrassed of my race, and then I become angry at the source of the embarrassment.

Act like a WHITE man by helping yourself, and NOT like a NIGGER looking for a handout! :mad:

[OneWhiteNation]

That hurts my feelings NBK.

All I'm trying to do is ellicit information from people who are more educated on the subject than myself. To the other guy, I did do a search on "propane" before I posted. The title of that post did not lead me to belive that I would find anything usefull inside. Of course now having seen it, I understand a little bit better the subject I am researching. However there are still questions I have that I cannot find the answers to online or from people I know in real life.

Previous posters on this thread have stated "safety valve disabled", but then give no information on how to accomplish this. Can anyone enlighten me?

Ok and here me out on this. I have another idea for exploding a propane tank. It involves:

A propane tank
A hotplate
An inverter
A car battery
A duffel bag

Just from the items, it should be evident the method I am thinking about. But let me say it anyway. The hotplate is rested snugly to the bottom of the propane tank, pheraps even duct taped heavily to it. The hotplate is plugged into the inverter and the inverter is affixed to the car battery. All the items are placed comfortably into the duffel bag when finished. Then when you want to explode the tank, you simply turn on the hotplate and leave the scene.

You guys think it would work?
Would the hotplate generate enough heat?

I think this method would eliminate the "smoking tank" problem that would render other methods useless in a public area.

If the safety release valve could not be disabled, how long between the activation of that valve and the explosion? Is there a loud hiss that accompanies activation of that valve?

I apologize to those of you who feel I've been rude. I'm just one of those guys who likes to get as much information on a subject before I begin testing. So as to avoid wasted funds and time on experiments that could have been avoided by simply asking you fine folks.

+++++++++++

Good grammar and and proper spelling are a Nazis best friend. Use more of it in the future. :) NBK

[c.Tech]

All I'm trying to do is ellicit information from people who are more educated on the subject than myself.

The only problem here is that asking for information without first contributing something is called a spoon feeding request.

You should have known this if you read the rules.

But then again, newbies… Rules? :rolleyes: Typical case of a newbie post, your lucky you haven’t been banned.

[Alexires]

OneWhiteNation - ....And you think NBK gives a flying fuck about your feelings?

On another note, has anyone seen the movie "A Long Kiss Goodnight"? Although in the movie they say its a 2 part explosive or something like that, I can see it being a BLEVE with internal coil heaters inside the tank.

When we are talking about a truck containing propane (or LPG) I always imagine something like this (http://www.meco.co.id/lpg.jpg).

Now, I don't know if it would be possible, but assuming you could get your hands on one of these tankers, would it be possible to insert some copper coils INSIDE the tank without compromising the structural integrity too much.

If it were possible, then these coils could be heated using the battery (that is kept charged by the running motor of the truck).

Interesting website with lots of figures on LPG here (http://www.elyenergy.com/sngtechdata.htm)

So lets see -

Based upon this (http://www.hansontank.com/propanetanks/propane%20tanks%20for%20trucks%201.jpg) tank (looks kind of perfect for a war time BLEVE), the makers (http://hansontank.us/lpg-tanks.html) say -

That the biggest one on this table can store 1150 gallons or 4352L (lets say 4400)

4400L is about 2552kg of LPG which would require 1084MJ of energy to vaporise (thanks Anthony).

This is where my calculations are stuffed. Thats how much energy it needs, so if we kept a car running with the alternater hooked to copper coils in the tank, how long do you think it would take to reach that energy?

You can get alternators that are rated at 250 Amps.

If that means 250 Amps per second at 12 volts, thats 3000Js-1.

Thats 0.003MJ a second which equats to roughly 100 hours before detonation....

Balls. Thats a bit too long. A few tanks of fuel later or one extra big fuel tank and you have a BLEVE. *sigh*

Anyway, it was just an idea. I'm a bit doubtful about those calculations, but still, it was worth a try.

I don't want to ask anyone to correct those calculations, but that propane tank looks pretty useful right?

[Chris The Great]

Not all the fuel needs to be vaporized, only enough to raise the pressure inside the tank to it's bursting point. Generally, this will be probably in the range of 1500-2000psi (for 20lb tanks, should be the same for the big ones too). And to make it better, the whole tank doesn't need to be filled with gas, since most of it is full of liquid propane. Generally, they only fill propane tanks to 80% capacity (of course, 80% capacity will be the figures they use for the maximum the tank holds) so there is not a huge volume you need to pressurize...

[nbk2000]

What about a simple pipe mortar on the top of a LPG tanker that'd be used to fire a cable over a high-voltage line, using that as a means of rapidly heating the LPG to BLEVE point?

[Alexires]

This website here (http://www.baftechnologies.com/afs_lpg.htm) says the tanks are built to withstand a pressure of 1000psi.

Lets assume that the tank withstands 1500psi before it ruptures.

How would one go about working out what temperature increase would be required for the pressure to go from 250 psi to 1500 psi?

I tried to use the Ideal Gas Law, but that only works for low pressures.

Here is what I did:

As the volume of gas is equal before and after (I hope) we can say that

P1/T1=P2/T2

Now, we know that the temperature before heating (T1) is 293K (lets say the tank is at 20*C), and the pressure inside the tank is 250psi which is equal to 1824689Pa.

The pressure we are looking for is 1500psi or 10443135Pa. These pressures are absolute pressure, not gauge pressure.

Substituting and all that, we get an answer for the T2 being 1676*C *sigh*.

Van der Waals equation is meant to work better, but I don't know how to use it *sigh*. Any help gentlemen? I gave it a shot and ended up with 17908K which is wrong.

[FUTI]

You made more then one mistake. You should take into your calculation that with rise in temperature you also vaporise portion of liquid inside the tank and that also rise the pressure inside the tank not only simple gas law equation.

Use Van der Waals since it has it merits...at least you can estimate using that equation for a given temperature maximum pressure that gas can have before turning liquid so you can get amount of energy used for heating up the liquid and the "border" pressure obtained.

Asume that yor tank have x kg of liquid and that remaining 20% of volume is vacuum (this is not true but makes first step easier you will get slight overshot in your result but fair estimate). Now you take the room temperature as starting point. Find the border pressure for the gas to become liquid at that temperature (you use T, estimated V, known a and b). Use this (or just little lower) as starting pressure. That should give you na rough estimate of amount of gas phase in this second step (you have estimated p,v and T,and Van der Waals a nad b are table values I hope). Then you calculate the temperature that gas phase should have so that tank burst (you use calculated n, estimated V, known a, b and tank bursting pressure). Repeat the step one for this new temperature. This is clearly overestimate. Now you go back to square one. Cycle that calculus couple time until the iterations give you some reasonable solution (temperature and pressure at which that amount of gas is really gas not liquid).

Amount of gas phase goes up in each cycle due to vaporisation and that with gas heating generate pressure. I hope that this has some sense it is been long time since I done with the physical chemistry tests. If anyone notice a glitch in my proposal please correct it.

[D-Fens]

Couldn't you use thermite on the propane tank? According to Wikipedia the rupture on the tank will cause boiling of the liquid due to the sudden drop in pressure therefore large amounts of vapour will be given off.

[nbk2000]

First of all, don't quote anything from Wikipedia here, as they don't know shit-all about explosives.

Secondly, as a liquified gas boils off, it carries away heat, causing the remaining liquid to get colder, until it reaches equilibrium with its surroundings, usually a slow boil.

So, you puncture the tank ABOVE the liquid line, it'll vent until it gets so cold from evaporation that it's a very slow boil.

Puncture it BELOW the liquid line, and it'll spray out liquid at a constant rate until the liquid is level with the hole.

And neither case will result in a BLEVE, as that depends on the sudden release of superheated fuel.

And invoking Thermite like some magic talisman, outside of proper context, is an almost sure fired way to get banned.

[30yearstoolate!]

On this show called Brainiac, I saw the above mentioned done. A "charge" of thermite was used above a 20 pound propane tank. This created a huge fireball of course.

But I believe it didnt rupture the tank but more cut a hole and light the gas that escaped. Which then continued to burn as more and more gas evaporated in the tank. This gas was propelled outside and burned. Not a "TRUE" BLEVE by defintion but it was damn cool.

[fractional distiller]

I know an individual who would really like to try this seeing as it is extremely accesible to everyone. This friend wants to take the standard 20lbs propane tank and use it as an explosive device. Theoretically since the propane tank holds 20lbs of liquid propane witch is about 90% propane with propylene, butane and or butylene additives equalling up to the other 10%.

This friend wants to make a self conatianed package. He has a tank that he has completely emptied of all propane gas and made sure of it becasue he is drilling a whole in it and placing a threaded holder in and has welded it into place. Then placed a spark plug into the threading and screwed it in along with an apoxy binder to assure no gas will be realeased and to ensure that the vessel can be pressurized.

The first encounter he runs into with his rig is that he wants it to be self contained so his approach is to find the upper and lower explosove limit of propane witch is 2.1%-9.5%. Then he figures if he were to calculate out what 9% of a 20lb tank hold and fills the rest of the tank by weight with molecular oxygen O2. The second is finding a licensed individual who will fill the tank only to a certian weight with propane or O2 and not notice a spark plug sticking out of the side of bottom.

Do you think that after the gasses have been allowed to mix for 2 days inside the canister that since even though the propane is in liquid state it does have the oxygen reguired for a detonation after a power supply is added to the spark plug? Or will this just catostrophically fail and end up wasting my friends time and money and killing him?

Any and all help would be greatly appreciated and if this is possible my friend has found himself a project to occupy himself with for the next two weeks of school and will make all neccesary actions to try to film and post this event if it were to ever happen theretically of course.

I find myself confused.

Is it even possible for a explosion to take place because what was mentioned earlier is the upper and lower limits for an explosion when the propane was mixed with air. So will the liquid propane even explode when mixed with O2 because the propane is liquid so what concentration would be needed for it to explode when delivered a charge from a spark plug or will it just simply sit there?

This is another problem I face the equation for the combustion of propane is
C3H8 + 5 O2 ==> 3 CO2 + 4 H2O when a stioch equation is made for this it requires 21% propane and 79% o2 for a combustion to work. So how can it be explosive at air saturation of 2-9% when 21% is needed for a total combustion in the first place.

I hope I havent wasted your time on this its just I would like to at least be able to contribute something to this fine forumn that I have been comming to for so many years now. Even if that contribution is some pictures of a detonation if its at all possible.

[Chris The Great]

Air is 21% O2.

You won't be able to get enough O2 into the tank, since propane easily turns to liquid, while air will not at the pressures the tank can hold. So you'll find that you reach the maximum pressure the tank can take (250psi) long before you have enough oxygen added.

[nbk2000]

I'd be worried about the possibility of spontaneous ignition as the oxygen is mixed with the fuel.

[FUTI]

NBK is right about safety AFAIR even petroleum industry fill its tanks under inert gas no matter are they empty or full to prevent oxidation of oil products placed in it. It is slow proces but makes nasty stuff that acts unpredictably.

Chris make good analysis about efficiency of the proposed device. Mixed in right proportion max posible "output" expresed in MJ/kg of mixture would be low due to the fact you can't make liquid oxygen under those pressure limits. Also mixed phase nature of that system makes it tricky. It will make blast...but how, how good, wich way etc. is beyond my knowledge.

If anyone is willing to risk his life he can try to make liquid oxygen by pasing oxygen through a flask cooled externaly by liquid nitrogen and then try to place that in the bottle that will be pressurised with propane minutes before detonation.

Does anyone find peroxydes usable in such device? Is there some blueprint or patent related to that?

[tijo77]

For curiosity purposes, I had experimented mixing Oxygen and Butane at least 4 times into a 2L soda bottle.
I tried to mix them with a 1:1 ratio by allowing approximately the same filling time to each gas (from that we can conclude that there was enough fuel/oxygen to permit combustion).
The four attemps were tried to be ignited electrically. Two of them were made to light about 1g of blackpowder and the last ones were made to light at least 15g of a recrystalized Sugar and Potassium Nitrate mixture molded to fit the bottle.



Every ignition system worked but I had only two explosions due to the pressure made by the gas created by the Sugar/Potassium Nitrate reaction.
The Fuel/Oxygen were pressurized. (At a point that the Butane was liquid into the bottle). *From other expirements only involving butane, it seems that a given container cannot be filled more than a certain ammount of butane (proportional to its size) until an equilibrium between the tank and the container is reached.
We had a lot of successful explosion by filling the bottle with pressurized oxygen and few milliters of different liquid fuel (such as Naphtalene).


Maybe that the Butane gas did not light because of its density comparing to Oxygen so they had not been mixed togheter. But it seems fairly propable to me.

Sorry for mistakes, since english is not my native language.

[Yafmot]

In the early '70s, a Navy munitions train went off in the west end of the Southern Pacific railyards in Roseville, CA. about 3 1/2 miles from where I lived. It was 8:00 AM, and the whole house shook, jerking me from a sound sleep (it was a Saturday). My Mom came running in (I was about 17 at the time), and said "Get up! The Roseville railyard's full of bomb craters!"

Taking this to mean we were being invaded (Sacramento was a HUGE target during the Cold War), I yanked on my pants, grabbed a twelve guage, stuffed my pockets with slug & 00 Buck loads, and ran out into the street, expecting to see bad guys parachuting into the area. She came running out after me, yelling "No, No! An ammo train went off." Some of the neighbors were already out mowing & watering and looking at me like I was nuts, while I grinned back sheepishly, grasping a shotgun in one hand and holding up my Lead-laden pants with the other.

As soon as I got back inside, my friend, Mark was on the phone, asking if I heard what was going on. I said "Yeah, I've gotta' see this!" so he went and got our other friend, Pete, and we headed out to Antelope, a small town East of Roseville where the incident was actually taking place.

The cops had Antelope Road blocked off about a third of a mile from the tracks, at the edge of a huge wheat field. There was a 7-11 store right there, so we parked behind it and began walking across the wheat field toward the action. A cop yelled that we really shouldn't be doing that, and if we got hurt, he wasn't going out there after our dumb asses.

The Boxcars were loaded primarily with 500Lb. Mk82s, but also some 750, 1,000 and 2,000 pound weapons, none of which were fused. Occasionally there'd be a low order det and, in a few cases, a partial high order. The bomb filling was Comp-B. By now, it's a couple of hours into the whole affair, and things are warming up nicely. On the track adjacent to the Navy train are some full propane tankers and, on the other side of that, a trainload of lumber. The wood has long since begun to burn, but because of the stacking it's from the outside-in. This means that the propane is being heated from both sides, with runny, oozing explosives on one side, and a trainload of lumber roaring away on the other.

About the time we'd gotten a third of the way across the field, one of the bombs went high order and flung a jagged piece of red-hot casing through the wall of a boiling hot tanker. You may have seen the newspaper photo on TV during one of those disaster/reality type shows. The fireball was easily 500 feet across and filled with railcars that had been tossed into the air like toys, along with a huge cloud of lumber fluttering around in the sky.

What the still picture couldn't depict, however, was the strange behavior of the overpressure. It began contracting first at the bottom, which had the peculiar effect of sucking all the airborne stuff, and some of the loose detritus on the ground, into a small area, almost a pile. So now theres a bunch of bombs, overturned propane tankers and twisted wreckage, liberally heaped with flaming wood.

While all this was going on, we stood there, absolutely dumbstruck, as the shock rolled across the field and nearly knocked us down. This was almost immediately followed by a scrap of casing about 10" long which whipped between our heads and half-buried itself in the ground about 50 feet behind us, setting the grass on fire.

After we'd stomped down the fire, one of my friends decided he needed a souvenier of the event so, you guessed it, he bends over and grabs the big piece of shrapnel that just missed us, burning the piss out of his hand. My other friend was working on a slushy he'd gotten at the 7-11, so we dunked his hand in that and I pried the metal loose from the ground with my boot & began pissing on the artifact, to cool it off. My friend got angry until I explained that this was the only way he was going to get the thing home. We spent the rest of the afternoon watching explosions and gathering up chunks of Comp-B that were raining all over the neighborhood

So, what have we learned from all this? Well, for starters we've confirmed that heating the propane under pressure adds immensely to the explosive force of the vessel rupture. Suborbital boxcars have a way of illustrating this.

Second, you don't have to heat the propane until the tank's rupture point is reached. These rail tankers ostensibly had operational rupture disks, none of which were sprung. This means that the BLEVEs were acheived well before this critical temperature/pressure was reached. All it took was a high order det adjacent to it, with sufficient shrapnel to initiate structural failure.

Third, a wood fire is adequate to reach this heat. You don't need thermite or anything fancy.

Fourth, keep your distance!!! Use a 30-06 or similar to break the thing, since it's obvious these explosions are capable of flinging big chunks of metal a very long way

Fifth, if you're going to pick up big pieces of burning hot metal, get some fucking welding gloves!!!

A couple of other tidbits. For one, NBK is exactly right about expansion cooling. Even tanks that have been heated for hours will be too cold to touch after they rupture. The cooling is such that there is almost always some residual liquid in the bottom of the vessel's remains.

Also, you think you might get a det out of a spray of gasoline and an HE initiator? Forget it. You may have been to an airshow where they simulate bombs. Big concussion, big ball of flame & black smoke. The way they do it is dirt simple. They make a small indentation in the ground (mostly so you can't see the device from the crowd area), lay down & connect a stick of 60% straight Dynamite in it, and lay a plastic bag with a gallon of gas on top of it. That's it! If there was any chance of the gas going high order, they wouldn't do it so close to the crowd. Especially not the "Wall of Fire."

[Bert]

You may have been to an airshow where they simulate bombs. Big concussion, big ball of flame & black smoke. The way they do it is dirt simple. They make a small indentation in the ground (mostly so you can't see the device from the crowd area), lay down & connect a stick of 60% straight Dynamite in it, and lay a plastic bag with a gallon of gas on top of it.


We generally have used a zig zag of det cord under the bag of gas.

[Yafmot]

It seems like the thermal input from the detcord would be kind of marginal. When these operators are going for a record in the Guinness Book, it's no dice if there is even one "cold shot" (lots of vapor, no flame). All that work for nought, just 'cause their Wall of Fire had one little breach in it.

The Warbird shows are a bit different. They have to sequence a lot of the charges, so there are many crossed lines. With detcord, you have to use standoff clips to keep from prematurely activating some of the elements. Frequently, even though the crossed line isn't detonated, there will be a fracture that will stop the det progression dead in its tracks. Too many duds, and your airshow's a dud.

Incidentally, I've seen where, on numerous occasions, a bag would just turn into a cloud of vapor and not ignite even in close proximity to a good shot, or even if the vapor and the fireball intermingled a bit. I'll have to ask about thaqt the next time I talk to those guys.

[Bert]

I too have seen failures to ignite with detcord, kinepack, and "dynamite". If one has Ti or Zr sponge available and puts a small volume in a sandwhich baggie on top of the HE and under the gas bag, one may see less of these failures. The added sparks may or may not be desirable, depending on the effect you want. Some are said to have used fine steel wool instead of the more expensive metals, but I was not impressed when I saw this tried.

[shooter3]

I'm posting this here, as it has already mentioned oxy/acetylene. I mostly use these as noise makers, but this weekend I used this for a legit reason. I'm making a lawn roller out of an old water tank. Tank has one convex end and the other has a concave end. I ground off the weld and found that it was pressed on before welding. I drilled a hole on the opposite end to put in a crowbar to bang out the free end. Damn! There was a baffle in the middle of the tank, welded in. I almost trashed the idea (crowbar wouldn't break the welds), but then I thought about using oxy/ acet to try to blow out the end of the tank.

The first attempt was under charged, but I did see that the end did move a little. I quadrupled the charge to about the size of a kids soccer ball. For safty sake, I aimed the tank bottom toward the woods (3/4 mile deep), twisted a trash bag up and poked it in the hole, filled it with the gases and put 5 inches of visco onto the bag. Lite the fuse and took cover. It was excellant! The bottom came out at high velocity, and travelled about 150 yards thru heavy brush. The first 10 ft of brush had a hole thru it the size that a 2 foot cannon ball would have made. My nieghbor came over as he thought the house had exploded from a propane explosion. It took a while to find the bottom. It wasn't all beat up, so I can use it. The burr was polished off by the blast, and the tank baffle was also blown out. Wow, what a labor saver!

[iHME]

Creative use for oxy/acetylene torch for sure.
Anyway I found a raghead bomb making video in my E&W folder labelled "GAZ" I think it was originally uploaded by nbk. The video decribes the making of a electrical igniter and the screwing it to a propane tank. After demonstrating the plain propane route, they add some oxygen to the propane cylinder and blow it up to show the power increase.
I uploaded the video to rapidshare.de so that you could take a look also.
If some kind soul who knows arabic could translate the texts and if possible the speech on the video. I'd be more then happy to subtitle the video.

http://rapidshare.de/files/39130397/GAZ.wmv.html

[megalomania]

We already have a thread about that video, and the other ones from the same source, and a request to translate the audio into English. At the very least a new voiceover in English could be dubbed into the files to replace the gibberish. That, and cutting the weird anti-American animation from the beginning.

All of the gibberish files and the videos are on the FTP in the UPLOAD/JIHAD folder. Nbk and I actually stumbled on the site searching for nbk2000 on google. They even made an arabic translation of my acetone peroxide page from my website. That particular form of flattery is creepy. Most of the files are completely unreadable, being arabic squiggles. I recognize a lot of the content as being translated crapbook material anyway, so it is no great loss. They also had a few translations of russian and American military manuals. The only thing that looked interesting were the illustrated diagrams of a few improvised explosive devices, that and the videos.