Be aware Fatal Error!

[KemppiFrog]

I was given a book in my early teens called Dr Wizards Science Secrets. There were several 'experiments' involving bangs. The gas filled tin can with holes in the top and bottom was one. We, natch, scaled it up with a dustbin. The lid really did go very high The trick, which we understood, was to over fill the the tin before lighting the top hole. Otherwise one might happen on the right mix, rather than watching the flame go lower as the air came in from the bottom. (This was coal gas, so lighter than air)

Anybody selling that book now would be banged up for years.

 

[mrcheese]

The gas filled tin was an experiment we did in physics at school to demonstrate explosive mixtures. Never tried a dustbin, but plastic lunch boxes would be filled with gas and sealed with tape ready for breaktime. Many parents must have wondered why lunch boxes came home with holes in them and teachers soon learned to confiscate any they found.

 

[brightspark]

I was given a book in my early teens called Dr Wizards Science Secrets. There were several 'experiments' involving bangs. The gas filled tin can with holes in the top and bottom was one. We, natch, scaled it up with a dustbin. The lid really did go very high The trick, which we understood, was to over fill the the tin before lighting the top hole. Otherwise one might happen on the right mix, rather than watching the flame go lower as the air came in from the bottom. (This was coal gas, so lighter than air)

Anybody selling that book now would be banged up for years.

we used to make them all the time using town gas fill the canister completely with gas. light the top hole and flame would apear when the gas equals 50 /50 with oxygen it would explode

 

[MattF]

To be fair cutting open a empty propane cylinder is for several reasons actually safer than an oil drum.

[..snipped..]

In other words an explosion wouldn't exceed the normal working pressure of the cylinder and unlikely to catastrophically fail in such a way as to seriously injure (unlike an oil drum or petrol tank).

You're overlooking one important factor there though. As soon as you start cutting/chopping the vessel, it's no longer a sound vessel, which is what that safe working pressure encompasses. Besides, even if it doesn't explode, a violent movement of the vessel caused by ignition of the contents could be just as deadly as an outright explosion.

 

[Shox Dr]

Did the same experiment at School with the tin on top of a bunsen burner. off the top popped.

The next lesson we were told would be outside. Upon the next lesson we all walked into the playing field where the teacher had a cardboard box about 2"sq. Leading form the box was a wire, back to where we were some 20yds away.

Nothing was said, as the teacher shuck the box and ran back the us picked up another box, and pressed a button....

It nearly took the lot of us off our feet

It was then he told us, that was a dust explosion.

It was then, we learnt dust explosions are just about the biggest explosion going short of a Neutron bomb etc, as it is only limited by the extent of the dust cloud. I've since learned dust explosions have killed many thousands of people in industry, notably Coal mines and Flour mills.

That was a few yrs ago now, and I have still to replicate it

 

[TechnicAl]

There used to be a flour mill in Rotherham. I blew up with monotonous regularity.

When I was young and had access to a proper chemistry lab we used to make things that went bang. The knowledge gets passed down but the experience doesnt. We did some very stupid things and its amazing how no-one got injured.

Looking back it was funny but we would have been sacked on the spot these days.....and rightly so.

 

[Shox Dr]

My dad blow a hole in the kitchen ceiling when he was a kid, making "stuff"*

He told me he'd paint it on anything and once dry it would go off with the slightest touch, even a fly landing on it would trigger it off

*They used to make snap-its from the same stuff. I believe it's the most unstable explosive known.

 

[TechnicAl]

My dad blow a hole in the kitchen ceiling when he was a kid, making "stuff"*

He told me he'd paint it on anything and once dry it would go off with the slightest touch, even a fly landing on it would trigger it off

*They used to make snap-its from the same stuff. I believe it's the most unstable explosive known.

was it black crystal like stuff

something tri-iodide I seem to recall

we used to sprinkle it under floor mats so when stood on they would lift up. It also worked on toilet seats.

 

[Shox Dr]

Never saw any, he made me swear never to make any. I did try to obtain the ingredients when I was a teenager but the local chemist soon sus'd me out.

Apparently if you try to buy the two ingredients on line now it's flagged up and the police are informed

 

[chunkolini]

Ammonium Tri-iodide
Distant memories of mixing bleach and Iodine.
Used to be marketed as fun snaps, they were filed with sand that had been soaked in it.
I think they can still be picked up in dodgy markets and joke shops.

Hmm getting off topic a bit aren't we?

 

[Rrunnach]

To be fair cutting open a empty propane cylinder is for several reasons actually safer than an oil drum. Firstly the contents have a high vapour pressure at room temp and thus once the cylinder valve removed is relatively easy to free of gas with eg. an purge. Secondly even if it did ignite the worst case pressure generated would be 8 times the initial pressure 1 bara if the cylinder is empty giving 8 bara overpressure which happens to be around the same as the vapour pressure of liquid propane. In other words an explosion wouldn't exceed the normal working pressure of the cylinder and unlikely to catastrophically fail in such a way as to seriously injure (unlike an oil drum or petrol tank).

Hot working on a pressurised vessel, within a public building is not acceptable, whether vessel went "poop" or "boom" would have HSE come down on us like a ton of bricks.

We are all responsible for each other, I took the step to have the vessel removed from the building.

One problem is individuals getting lulled into a false sense of security, then one day, KaBooM....................this thread alone, has made members think twice before doing similar hot work that they got away with previous.

RIP.

 

[KemppiFrog]

Yes. But we made ammonium tri-iodide at school. Seriously dangerous stuff. Remember a kid got his leg blown off. Took some to a party in a jar (wet, so 'safe) then leaned up against a radiator for a while........


Back to topic: A couple of race mecs in the US decided to ride an oil drum with some exotic alchy fuel, by lighting the open bung hole. Expected a bit of rocket assisted fun in the paddock. I think one survived.

 

[W4yne]

I wonder if he used petrol to clean out the oil from the barrel?

 

[Lewis Medlock]

It nearly took the lot of us off our feet

It was then he told us, that was a dust explosion.:

http://www.youtube.com/watch?v=3d37Ca3E4fA

or google "CSB Dust Explosion"

They say it's the second bang that does the damage, the first bang loosens more dust from the rafters.


Jim

 

[Browser]

I've only ever used an air nibbler or air shears to cut oil drums, these are slightly safer than electrically-powered tools as they don't tend to spark and you dont get sparks at the cutting head. Cengar air hacksaws are good in this regard too, which is why I keep looking for them on Ebay.

 

[gordon stephenson]

Cengar saws are excellent tools, I have used them a lot on power stations for cutting out restricted access pipework.Most methods of cutting metal have the potential to create sparks. And it only takes ONE!!!

 

[Keith 66]

Back in 82 i was working in boatyard at Old Leigh, I got a job to do welding up an exhaust silencer off a fishing boat, the wadding inside was full of oil & i was welding away with the old oxy acetylene set when it started to pour out thick white smoke, i remember stepping back & the silencer made a funny noise & took an enormous toke of air. This trange phenomenon was immediately followed by a very loud explosion & muzzleflash from the end.
Couple of days later we had a far bigger bang when the boss put a box of rubbish in an oil drum brazier it had a can of easy start in it. It burst the drum like a baked bean can. Happy days!

 

[Shox Dr]

http://www.youtube.com/watch?v=3d37Ca3E4fA

or google "CSB Dust Explosion"

They say it's the second bang that does the damage, the first bang loosens more dust from the rafters.


Jim

I can't believe it took until 2008, for the Americans to realise, the dangers of dust explosions. They've been happening in industry ever since the cotton mills, I believe some of the worst explosions ever were in Cotton mills, centuries ago

 

[pedrobedro]

Coal dust and flour are also causes of some explosions which have sunk ships in the past before precautions became more stringent.

 

[Wedg1e]

Think I read domewhere that the biggest man-made explosion prior to the nuclear industry has been attriibuted to a munitions ship that went pop in a bay off Canada around WW1; the shock-wave levelled nearby towns as I recall. Off to Google...

Edit:

http://en.wikipedia.org/wiki/Halifax_Explosion

OK, it was in Halifax and it was two ships, not one, but it was still a big bang