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Arcane
12-09-2011, 08:15 AM
http://bbs.homeshopmachinist.net/showthread.php?p=721098#post721098

SGW
12-09-2011, 08:33 AM
Something like that could really ruin your day. That guy is lucky indeed.

Doesn't acetylene have an explosive range from 4% to 94% concentration, or something?

justanengineer
12-09-2011, 08:37 AM
Something doesnt seem quite right here to me.

Regardless, he must not have had the cap on the cylinder, or else a slight "bump" would not have done anything, unless his idea of a slight bump is significantly different from mine.

And yes, the explosive range of acetylene is quite broad. ~2%-~80%, compared to ~2%-~10% for propane...but they both vary a bit depending upon who you ask.

KiddZimaHater
12-09-2011, 08:40 AM
Note to self:
Don't put gas cylinders in trunk.

alanganes
12-09-2011, 09:15 AM
Something doesnt seem quite right here to me.

Regardless, he must not have had the cap on the cylinder, or else a slight "bump" would not have done anything, unless his idea of a slight bump is significantly different from mine.

And yes, the explosive range of acetylene is quite broad. ~2%-~80%, compared to ~2%-~10% for propane...but they both vary a bit depending upon who you ask.


Taken at face value, my guess would be that it was a "B" or even "MC" tank that does not have a cap.

Using an electric window to clear a vehicle of explosive gas would not have been my first choice. At least I'd like to believe I'd know better.

Dr Stan
12-09-2011, 09:18 AM
I've seen a similar pic of a small Japanese PU with a similar outcome. Only in that case the inside light switch on the door set off the acetylene.

Willy
12-09-2011, 09:27 AM
I've seen a similar pic of a small Japanese PU with a similar outcome. Only in that case the inside light switch on the door set off the acetylene.

Ditto.
I'm very surprised that didn't happen in this case.
Hindsight is always 20-20, but in retrospect a baseball bat to the windows would have been the wiser move.

When in doubt....phone the FD.

Richard Wilson
12-09-2011, 10:04 AM
What an idiot. The standard warning from gas suppliers (utilities)in the UK at least, is if you smell gas, do not operate any electrical switches. He's lucky it didn't blow when he started it up to drive out of the garage, at least this way he didn't blow up the house as well.

Richard

Evan
12-09-2011, 10:14 AM
The flammable limits for acetylene in air are 2.5% to 81%. That is a very wide range. More important, acetylene is one of the gases that will switch from combustion to detonation, especially in a confined space. Those images look like it detonated.

Black_Moons
12-09-2011, 10:29 AM
Yea I think the second he opened the door and smelt the gas, he should of gotten the hell outta there.. And idealy back to his house to turn the power off to the garage!

Not sure if the fire department would need to be called.. But then, they likey at least have some hydrocarbon gas detector so they could detect when it was safe to approch the vehical and turn the tank off (or if its just leaking too fast, need to wait till it runs dry... Hmmm, A tank on its side.. would'nt that leak acetone?)

Also, Why was a tank being stored inside a truck anyway??? That seems exceptionaly foolish.

Weston Bye
12-09-2011, 10:57 AM
Years ago, I kept my propane torch, striker and fuel tank in an ammo can, a nice sealed container, until.... I went to open the can once and it popped open when I uncammed the latch, accompanied by the strong smell of propane. The tank (schrader?) valve had been seeping.

Mcgyver
12-09-2011, 10:58 AM
Taken at face value, my guess would be that it was a "B" or even "MC" tank that does not have a cap.
.

that always bothered me, the B bottles not having a cap....disaster waiting to happen.

BMW Rider
12-09-2011, 11:38 AM
Another issue with acetylene is that it must only be drawn off the tank when its positioned vertically. If the tank is laying down, acetylene bubbles will percolate off the acetone carrier in the tanks matrix but not be drawn off the valve and can spontaineously explode. Acetylene is actully very unstable at pressure which is why the tank has the porous matrix in it and the acetylene is disolved in the acetone solution.

Jim Caudill
12-13-2011, 04:29 AM
There are probably hundreds of thousands of plumbers driving around in their vans with their "B" cylinders in the back everyday. There will always be the "freak accident" or highly unusual occurrance, but I suppose we ought to be surprised there are not more incidents.

I like the looks of the Lenox "Tanktote":
http://tinyurl.com/lenox-tanktote

I was reading about the history of Allison the other day and how Jim Allison was linked with "body by Fisher" guy Carl Fisher. They started the Concentrated Acetylene Co with another guy named Avery, and after Avery left, they renamed the company Prest-O-Lite. They were the original folks that came up with Acetylene gas in steel tanks.

They had numerous explosions in their early days of manufacturing and filling tanks.

I rarely see a plumbing or A/C service vehicle that has their acetylene tanks outside. Come to think of it, the only external rigs I think I have ever seen are the welder guys that come out to a jobsite or fleet maintenance guys.

The Artful Bodger
12-13-2011, 04:40 AM
. They were the original folks that came up with Acetylene gas in steel tanks.

.

????? I thought we had the French to thank for that development???

j.bain87
12-13-2011, 04:46 AM
This fella wasn't so lucky.

The news footage clearly shows a set of oxy, acetylene hoses after the explosion, only taking a wild guess that they were the cause.
He hadn't even got to the van, he was approaching it and used the infra red button to open the vehicle and BOOM.


http://www.theage.com.au/victoria/hissing-sound-before-fatal-mulgrave-van-blast-20111212-1oq3q.html

Evan
12-13-2011, 10:00 AM
It says he was sitting in the van. The remote control story was about an earlier incident. Quite the blast according to the story. That is definitely an example of the gas detonating rather than combusting.

Tony
12-13-2011, 10:21 AM
these kind of stories always scare the daylights out of me.
I've got a full size oxy-acetylene rig in the shop.. chained to the
wall, with hoses coiled and hanging on a hook.

Should I take the regulators off every time? Or are they safer
than these 'freak accidents' make them out to be?

And my shop isn't all that big; I could be welding 5' away from
those things.

Every fab shop I've ever been in has had them right there, sitting
on a cart, right next to all the other welding gear.

The only horror stories I've ever heard first hand usually involve
the classic "it fell over, valve broke off, went through 15 brick walls,
4 chain link fences, and a fire hydrant"

When I transport them (only ever to the weld supply to drop off / fill)
they're always with their caps on, but I do have to lay them on
their sides to get them into my jeep.

So.. how big of an idiot am I?

And it doesn't sound like its any safer to get 1/2 sized bottles.

-Tony

Boucher
12-13-2011, 10:30 AM
Here in Texas there was an explosion from a Acetelene bottle in the trunk of a car that was finnaly attributed to a leaking safety seal. There are metal seals that are designed to melt and open the cylinder if it is in a fire. There is a significant difference in deflegration and detonation. Burning gas in a closed volume is a big bang but is dwarfed by detonation of the same volume.

macona
12-13-2011, 12:20 PM
Something doesnt seem quite right here to me.

Regardless, he must not have had the cap on the cylinder, or else a slight "bump" would not have done anything, unless his idea of a slight bump is significantly different from mine.

And yes, the explosive range of acetylene is quite broad. ~2%-~80%, compared to ~2%-~10% for propane...but they both vary a bit depending upon who you ask.

Not all cylinders are required to have caps. MC and B tanks dont. And some cylinders can have slightly leaky valves that will miss inspection but when in a confined space, like the vehicle, leak enough to become explosive.

Dont leave your tank in the car.

macona
12-13-2011, 12:23 PM
these kind of stories always scare the daylights out of me.
I've got a full size oxy-acetylene rig in the shop.. chained to the
wall, with hoses coiled and hanging on a hook.

Should I take the regulators off every time? Or are they safer
than these 'freak accidents' make them out to be?

And my shop isn't all that big; I could be welding 5' away from
those things.

Every fab shop I've ever been in has had them right there, sitting
on a cart, right next to all the other welding gear.

The only horror stories I've ever heard first hand usually involve
the classic "it fell over, valve broke off, went through 15 brick walls,
4 chain link fences, and a fire hydrant"

When I transport them (only ever to the weld supply to drop off / fill)
they're always with their caps on, but I do have to lay them on
their sides to get them into my jeep.

So.. how big of an idiot am I?

And it doesn't sound like its any safer to get 1/2 sized bottles.

-Tony


You are fine. You dont need to do anything.

macona
12-13-2011, 12:27 PM
that always bothered me, the B bottles not having a cap....disaster waiting to happen.


Not really. The cap is just there to prevent the valve from getting broken off and that basically never happens on these small bottles. Even small high pressure tanks up to about 40CF dont need caps. It past that point when they become heavy enough to break off the valve if they fall over.

wierdscience
12-13-2011, 01:15 PM
Forgetting to turn the valves off is what does it most of the time.Regulators,hoses and the torch itself can all leak by small amounts that won't show up anywhere but in the wallet,enclose them in a small volume of air like a trunk or van and it's an all together different story.

Jim Caudill
12-13-2011, 01:42 PM
All I have ever done is shut the tanks off and bleed the acetylene and oxygen off separately. The regulators are "unloaded" and contain very little gas in the hoses.

I forget the details, but Mythbusters did a significant study of breaking the valves on high pressure tanks. The first attempts were unsuccessful due to a couple of issues. First was the type of break that occurred when the tank was hit, simulating a knock-over or bumping type of impact. They couldn't get the jet of gas they were expecting. The second issue had to do with the type of valve that was used. Apparently, the high pressure tanks have some kind of special valve or something that prevented a high-pressure jet, when broken.

They had to go back and talk to the gas/cylinder folks to find out why they couldn't get the desired result. IIRC they had to get tanks specially equipped with a different valve, and arrange for a guillotine type of device to shear the valve off cleanly. Only then could they produce the spectacular results of a cylinder rocketing thru a block wall.

on edit:
I found a description of the episode (#63 Oct 18, 2006).
the following is a quote from the website:

"They talked to George Ratermann of Ratermann Manufacturing, Inc about the myth. Ratermann supplies valves and cylinders but has never heard a first-hand account to verify the story, though he has heard the myth. Ratermann expressed some concern that their rig would only get a partial break on the valve, which would prevent the cylinder from flying straight."

George Ratermann was almost prophetic in that they were unable to get the valve to break in such a way as to get a "propelling jet" type of break. I guess the valve was the standard one, but it was carefully positioned and guillotine blade was aimed to try and get a clean separation. The youtube video shows they were able to get the valve to completely shear and depart the tank. All of this is to say that Yes, the tank can do this; but only under ideal conditions. But, they designed the test from the start to do this and were unsuccessful. Their first attempt could only fracture the valve enough to produce a leak that took 45 minutes to evacuate the tank.

Paul Alciatore
12-13-2011, 04:17 PM
Many people do not realize that whenever you turn an electric switch on or OFF, you get a small spark inside it. It is the OFF that surprises many of them as they feel that OFF is safer than on. In fact turning it off may actually produce a larger spark and hence a better chance of ignition than turning it on.

If a switch is on in the presence of flammable gas, LEAVE IT ON. Kill the power at a disconnect point that is far from the gas.

Simply saying "Do not operate switches" does not convey the danger of turning them off and many may think that means to turn them off to cease operation of whatever is on. Boom!

Black_Moons
12-13-2011, 05:59 PM
Many people do not realize that whenever you turn an electric switch on or OFF, you get a small spark inside it. It is the OFF that surprises many of them as they feel that OFF is safer than on. In fact turning it off may actually produce a larger spark and hence a better chance of ignition than turning it on.

If a switch is on in the presence of flammable gas, LEAVE IT ON. Kill the power at a disconnect point that is far from the gas.

Simply saying "Do not operate switches" does not convey the danger of turning them off and many may think that means to turn them off to cease operation of whatever is on. Boom!

Correct, You are much better off not touching the switch then turning it off, Most powered appliances are not an ignition risk anyway. (Exceptions: Brushed electric motors, Heaters of any kind (Thermastat = Automatic switch that is usally exposed), air compressors, Maybe incandesent/halogen light bulbs?)

And by 'exceptions' I mean those appliances are ignition risks. I do not mean you should attempt to turn them off from a nearby switch.

The place to turn the power off is upstream where there is no gas, And where you are safe from the explosion should it occure.

macona
12-13-2011, 06:26 PM
All I have ever done is shut the tanks off and bleed the acetylene and oxygen off separately. The regulators are "unloaded" and contain very little gas in the hoses.

I forget the details, but Mythbusters did a significant study of breaking the valves on high pressure tanks. The first attempts were unsuccessful due to a couple of issues. First was the type of break that occurred when the tank was hit, simulating a knock-over or bumping type of impact. They couldn't get the jet of gas they were expecting. The second issue had to do with the type of valve that was used. Apparently, the high pressure tanks have some kind of special valve or something that prevented a high-pressure jet, when broken.

They had to go back and talk to the gas/cylinder folks to find out why they couldn't get the desired result. IIRC they had to get tanks specially equipped with a different valve, and arrange for a guillotine type of device to shear the valve off cleanly. Only then could they produce the spectacular results of a cylinder rocketing thru a block wall.

on edit:
I found a description of the episode (#63 Oct 18, 2006).
the following is a quote from the website:

"They talked to George Ratermann of Ratermann Manufacturing, Inc about the myth. Ratermann supplies valves and cylinders but has never heard a first-hand account to verify the story, though he has heard the myth. Ratermann expressed some concern that their rig would only get a partial break on the valve, which would prevent the cylinder from flying straight."

George Ratermann was almost prophetic in that they were unable to get the valve to break in such a way as to get a "propelling jet" type of break. I guess the valve was the standard one, but it was carefully positioned and guillotine blade was aimed to try and get a clean separation. The youtube video shows they were able to get the valve to completely shear and depart the tank. All of this is to say that Yes, the tank can do this; but only under ideal conditions. But, they designed the test from the start to do this and were unsuccessful. Their first attempt could only fracture the valve enough to produce a leak that took 45 minutes to evacuate the tank.

Its definitely not a myth. A fab shop locally where a cousin of one of my best friends had a bottle fall over, hit a table and take off across a shop and through the cinder block wall.

mike4
12-13-2011, 07:09 PM
My last service van had a cabinet which was vented to the outside and sealed from the interior of the vehicle witha clamping system to hold the bottles upright .
I was always told by fire authorities that was the only safe method of transport unless it was a vehicle with an open tray .
I have seen many people scoff at similar setups for being too costly or takes too long to put the gear away , or cant get enough cylinders in that stupid box.
These idiots are often typical of the latest crop of "tradespersons"
they are more interested in going home or to the pub than simple safety methods , they are the first to try to blame someone else if any thing happens .
Time for the authorities to come down hard on anyone who transports gas cylinders in or on any form of vehicle incorrectly, imagine if this had happened in the car park of a shopping centre packed with moms and kids .

Michael

Black_Moons
12-14-2011, 03:11 PM
My last service van had a cabinet which was vented to the outside and sealed from the interior of the vehicle witha clamping system to hold the bottles upright .
I was always told by fire authorities that was the only safe method of transport unless it was a vehicle with an open tray .
I have seen many people scoff at similar setups for being too costly or takes too long to put the gear away , or cant get enough cylinders in that stupid box.
These idiots are often typical of the latest crop of "tradespersons"
they are more interested in going home or to the pub than simple safety methods , they are the first to try to blame someone else if any thing happens .
Time for the authorities to come down hard on anyone who transports gas cylinders in or on any form of vehicle incorrectly, imagine if this had happened in the car park of a shopping centre packed with moms and kids .

Michael

I for one, Thank you for taking the extra time and cost to do it right, and serve as a POSATIVE example to everyone else.

justanengineer
12-14-2011, 07:22 PM
Its definitely not a myth. A fab shop locally where a cousin of one of my best friends had a bottle fall over, hit a table and take off across a shop and through the cinder block wall.

Definitely agree. I saw it once when I was a kid in the sawmill. An O2 bottle was nicked by the loader's forks and was out back tearing across the yard before anyone realized what had happened. They dont fly straight for long, but do have spurts where they cover quite a distance before turning and zipping in another direction. It didnt have any conrete to deal with, but did cover a few hundred feet before finally fizzling out.

Machtool
12-15-2011, 07:13 PM
Another refrigeration fitter, was killed in Darwin this morning, (Friday). Thatís 2 in 5 days down here.

http://au.news.yahoo.com/latest/a/-/article/12373256/man-dies-in-suspected-gas-bottle-blast-in-darwin/

Phil.

macona
12-15-2011, 08:32 PM
killed in Darwin \[/URL]

Phil.

How appropriate.

wierdscience
12-15-2011, 08:52 PM
Dam,guess he didn't watch the evening news.