Acetylene tank safety?

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All it takes is a drop or two of water in a pipe and no matter how much heat is apllied you usually windup badly oxidizing the pipe / fitting flux and just botching the entire job. Bread works great though! Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy.
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Roy wrote:

No, it is actually FAR worse. We had a welder in town who picked up a new Acetylene tank from the welding supply on the hottest afternoon that summer. He left it in his black Camaro in the front drive, and went around the back to visit with his family in the back yard. There was essentially NOTHING left of the car. He called the bomb squad, and after about an hour, the FBI got the picture together, and said "you left a FULL Acetylene cylinder in a BLACK car in the HOT sun, and you call US about a bomb in your car? YOU IMBECILE! You blew up YOUR OWN car, and your whole neighborhood, too!"
Technically, the condition is called a deflagration, where a near explosive wave propagates through unstable chemical compounds. Acetylene contains a triple carbon bond, which contains a HUGE amount of chemical energy. Heat, high pressure, or sharp impacts can set off a deflagration, and develop pressures somewhere in the range of 10,000 - 100,000 PSI. This is less than a high explosive would deliver, but way more than a failed high-pressure gas bottle.
I don't use Acetylene, but Propylene (supposed to be the equivalent of MAPP, which is a trademark.) It is supposed to be impossible for it to deflagrate, except possibly if the whole tank was incinerated. It is also a lot cheaper, the tank holds liquid, and therefore MANY hours of torching more than with Acetylene.
Jon
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Hey, there's the info I've always wanted. I had wondered what the reaction might be when no oxygen was present, and now I understand. Now, what is the REAL pressure level that acetylene will explode at? Or is it temperature dependent? The regulator gauge is redlned at 15 psi, but there is 150 psi gas upstream of the regulator before there's any liquid. It it something to do with pressure/temperature/impact risks to the hoses?
Dan
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Dan_Thomas snipped-for-privacy@yahoo.com (Dan Thomas) wrote:

15 PSI is where acetylene *CAN* start to break down. Not where acetylene *WILL FOR SURE* start to break down...
I've often wondered the same as you - "If 15 pounds is the "magic" number, why is it OK to have 10 times that between the "raw tank" side, and the "regulated hose" side?"
My theory is that it's partly the pressure, partly the quantity, and partly the lack of any significant "stimulation" - Above 15 pounds isn't neccesarily "kaboom" unless there's enough acetylene available to make it happen, and some external energy source (pressure, shock, heat) to trigger it.
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Dan Thomas wrote:

Supposedly, it has something to do with the free volume at the 150 PSI. In other words, a whole tank of Acetylene at 150 PSI is a bomb, but a properly packed and acetone-saturated tank with just a little free volume right at the top is not. Don't ask me for the physics behind this, I don't know it.
Jon
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"Jon Elson" wrote: (clip) In other words, a whole tank of Acetylene at 150 PSI is a bomb, but a properly packed and acetone-saturated tank with just a little free volume right at the top is not. (clip) ^^^^^^^^^^^ Earlier on, someone gave a website regarding the safety of pressure cylinders, which contained the warning that DENTED acetylene cylinders are dangerous, because there can be a separation of the packing from the sidewall, so a potentially explosive small volume of undissolved acetylene can collect. This has been floating around in the hollows of my skull ever since. How can it be dangerous to have a little sliver of acetyleye gas along the sidewall of the tank, but totally safe to have acetylene at the same pressure on the high side of the regulator?
Maybe someone who is an expert on this can clarify.
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The problem with places like basements is the low air exchange rate that such places have. This allows the possible venting/leakage of the cylinder to acculumate to the point where a flame sets it off in a nasty explosion. Keep the cylinder upright and the system of storage inside the cylinder of the gas will keep on working right.
-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!
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I asked the fire marshal at work about this - for my B sized acetlyene tank. He said it was legal to have it in my basement shop - but...
I asked if he would have one in his basement at home, and he said 'no way.' So I exiled my torch rig to the (detached) garage. I think the problem is not so much pilot lights (as long as the tank valve is not leaking) but rather, what happens if there is a fire for some other reason.
Jim
================================================= please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com =================================================
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but
flames
that
Robin,
Heres a short video on bottled gas safety......
http://www.gotoslawek.org/film/Langeweile%20im%20Lager.mpeg
2.54mb--enjoy.
--

SVL



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Fantastic! I had to watch it about 6 times, nearly ending up in a laughing seizure.
Encore! Encore!
Harry C.
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Explosive ratio of acet. is 3 to 83 % in air at atmospheric. IIRC.
John H.
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but
flames
that
Now IIRC acetylene is heavier than air so a leak allows a cellar to fill with the gas. When the level reaches the pilot light, WHOOSH. Keep the bottle in a well ventilated building above ground and there's no problem.
John
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John Manders wrote:

This happened to my cousin and her huaband several years ago in the Dallas area. He'd borrowed an O-A rig from work to do some quick repairs at home. This was OK'ed by his boss. He was a manager, not a welder, but could weld. After he finished, he put both tanks in the trunk of his car, in their closed, attached garage. The water heater was also in the garage. Evidently the acetylene tank was leaking, or he hadn't gotten it shut-off completely. During the night they were violently awakened by the explosion. Fortunately, their bedrooms were on the opposite end of the house, and they got out. Part of the car was found across the street in their neighbors front yard. The roof had cedar shake shingles and went up like dry kindling. They got out, but there home, cars, and belongings were gone. Because he was relatively high in the company, they went after the tank supplier. In the end my cousin's husband got everything replaced that was replaceable.
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vaguely proposed a theory ......and in reply I say!: remove ns from my header address to reply via email
And in Oz we are banning the sale of amm nitrate! Talk about knee-jerk political stunts!

*******************************************************
Sometimes in a workplace you find snot on the wall of the toilet cubicles. You feel "What sort of twisted child would do this?"....the internet seems full of them. It's very sad
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snipped-for-privacy@iinet.net.au says...

Hi Nick, What are your farmers using for fertilizer?
Jim Kovar Vulcan, Mi
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On Tue, 25 May 2004 06:57:20 -0500, Jim Kovar
......and in reply I say!: remove ns from my header address to reply via email

DUUUUH! This is Govmint polisy man! Who cares? <G>
The reply will probably be "dollars".
Seriously, the farmers have asked the same question. At present Amm Nitrate is till _sort_ of legal, with lots of talk of treating it as an explosive; licenses, storage etc. Trouble is, one company voluntarily withdrew its Amm Nitrate and farmers were asked to return their stocks. So we have a looming election and a company that stands to sell costlier fertilisers!
I do have to say that I was looking at possible ways to make a bomb using other means of getting O2 spread amongst fuel, with the idea of complaining about this daft idea. NH4NO3 (like other solid oxidisers) has a frightening amount of oxygen tied up in it per weight! I am not sure how much of this is available for conflagration, but even 1/4 of it is pretty scary. *******************************************************
Sometimes in a workplace you find snot on the wall of the toilet cubicles. You feel "What sort of twisted child would do this?"....the internet seems full of them. It's very sad
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