Don't store Oxygen and Acetylene together in an LPG bottle and attempt to weld

[IanB]

Yea, that's a convincing argument right there  That's my clue to stop the discussion with somebody.

Yes, I'm sorry about that, but what else can I say? To let you know that you are wrong can be done briefly. To educate you into a better understanding may take a long time. It may even take a complete education in chemistry, physics, fluid flow, and combustion engineering.

Some insight may be gained from looking at few of Cody's recent YouTube videos on combustion in a vacuum chamber (Cody's Lab). He found (somewhat surprisingly) that gunpowder will not burn in a vacuum, even though it does not need an external source of oxygen. In combustion, pressure is very important. At high pressure things burn fast. At low pressure things burn slowly or not at all.

[langwadt]

Yea, that's a convincing argument right there  That's my clue to stop the discussion with somebody.

Yes, I'm sorry about that, but what else can I say? To let you know that you are wrong can be done briefly. To educate you into a better understanding may take a long time. It may even take a complete education in chemistry, physics, fluid flow, and combustion engineering.

Some insight may be gained from looking at few of Cody's recent YouTube videos on combustion in a vacuum chamber (Cody's Lab). He found (somewhat surprisingly) that gunpowder will not burn in a vacuum, even though it does not need an external source of oxygen. In combustion, pressure is very important. At high pressure things burn fast. At low pressure things burn slowly or not at all.

I think idea here is that at some low pressure in the bottle the flow out of the bottle is slower than the flame front so
the flame travels up the hose and into the bottle at which point the burning inside the bottle increases the pressure
and eventually it explodes

[taydin]

I think idea here is that at some low pressure in the bottle the flow out of the bottle is slower than the flame front so
the flame travels up the hose and into the bottle at which point the burning inside the bottle increases the pressure
and eventually it explodes

Exactly. And that's why flashback arrestors are put on the hoses, so that if the flame travels back the hose, into the cylinder, the flashback arrestor closes and prevents a disaster.

[IanB]

I think idea here is that at some low pressure in the bottle the flow out of the bottle is slower than the flame front so
the flame travels up the hose and into the bottle at which point the burning inside the bottle increases the pressure
and eventually it explodes

Yes, but that is about flow velocity and not pressure. Also, when you have a fuel/oxygen mixture the speed of a moving flame front can be much faster than the flow velocity in a tube. That's why a normal gas torch mixes fuel and oxygen right at the tip. There is also the situation that the flow is controlled by some kind of lever at the torch end to control the flame size. For a given flame size the flow velocity in the tube is slower when the pressure is higher because for a given mass flow the product of velocity and density is constant.

True that when the velocity slows close to zero the possibility of flash back is much higher, but I predict the explosion would happen long before then.

The really crucial thing is that you never, ever mix oxygen and a flammable material in a confined space. Ever.

[chris_leyson]

I had no idea acetylene was so volatile, didn't teach me that in school metalwork classes. My only attemp at oxy-acetylene welding was a disaster, mostly unsupervised and I used a cutter to 'weld' some coffee table legs together, well that explained why the steel disapeared  Some time later I made a small steam engine, it would never have worked, too much slop in the mechanics. Anyway building a steam boiler was considered to be " a little dangerous" and with no available compressed air supply the other sources of compressed gas were oxygen or acetylene, oxygen was considered to be less than safe because of the graphite covered string used as piston seals so acetylene it was then.
Quite unremarkable really, the mechanics didn't budge because of the poor machining and the place stunk of acetylene. Looking back I sometimes think  you couldn't do that nowadays.

[coppercone2]

if the man did this and is a welder I am convinced he was extremely intoxicated

[tooki]

Who's told you that rubbish?

Let's quash that particular BS right now though, a link, to a government page:

https://www.gov.uk/buying-carrying-knives

Heh, yyyyeah… Americans have lots and lots of crazy misconceptions about the Old World, both positive and negative.

(I'm an American living in Europe. I have had to explain to people in USA that no, I don't pay 60% income taxes. No, preservatives and food coloring and other additives aren't actually categorically banned here. No, there aren't death panels deciding who gets healthcare. No, there aren't cows hanging out on my street in the city. No, not everyone in Europe is fancy and erudite, every place has its own equivalents to white trash and hood rats. No, there actually is McDonald's here, and it's popular. And yes, they DO have cheddar cheese in England. Funny, that…  And no, not everyone in Switzerland is filthy rich!)

Nooo, we can get Cheddar here in England? All this time I've been smuggling Cheddar in from Belgium and nobody told me?

Seriously though, some of the stories I've been told by Americans about my own country, I don't know if I should laugh or cry, one of my favourites came from my partner who used to work in a London hotel, a sweet American couple wanted to know if she could book them a taxi to Edinburgh so they could have afternoon tea at the castle and be back for their dinner that evening.

Hah, fantastic!

Many a Swiss I've talked out of their plan to visit USA for 2 weeks, intending to rent a camper (caravan) and drive around literally half of mainland USA… they're like "well LA and Las Vegas are right next to each other, right? Like maybe a half hour or so?" (It's more like 4-5h in good traffic.)

They're still vastly outnumbered by the sheer masses of Americans who don't know that Switzerland and Sweden are different things. I couldn't begin to tell you how many times I've been asked "Oh!! You lived in Switzerland?? How's your Swedish?!" My usual reply is that since I've never been to Sweden, I only know what I learned from the Ikea catalog…

[Cerebus]

They're still vastly outnumbered by the sheer masses of Americans who don't know that Switzerland and Sweden are different things. I couldn't begin to tell you how many times I've been asked "Oh!! You lived in Switzerland?? How's your Swedish?!" My usual reply is that since I've never been to Sweden, I only know what I learned from the Ikea catalog…

It's lucky that Swaziland changed its name this year then...   "Mom, I went to get the money out of the Swiss bank and it's really hot here, there's this weird black and white striped horse wandering down the street, there's a heck of a lot of black folks here, even more than in Baltimore, and that Swedish language course I took is useless, nobody understands a word I say!"

[edy]

I remember using oxy-acetylene torch back in high school, I guess I would have been 14 or 15 years old? I welded together an anchor out of bits of pipe and covered it with brass solder. It was awesome! Thick black powdery smoke before the oxygen was turned on.... it would get in my nose. I remember blowing my nose and finding black soot in there.

Anyways, when it came to turning it off... our shop teacher always said "A" before "O" or UP YOU GO! I will never forget that line.

I've never fully understand why, and I see there are different opinions, something to do with "flashback" and "pop". Maybe someone can explain. But yes.... we had the opportunity to oxy-acetylene at a very young age and without incidence, despite it being a school with kids running around of various intelligence levels.... kind of surprising now that I look back at it.

[bd139]

I remember using oxy-acetylene torch back in high school, I guess I would have been 14 or 15 years old? I welded together an anchor out of bits of pipe and covered it with brass solder. It was awesome! Thick black powdery smoke before the oxygen was turned on.... it would get in my nose. I remember blowing my nose and finding black soot in there.

Anyways, when it came to turning it off... our shop teacher always said "A" before "O" or UP YOU GO! I will never forget that line.

I've never fully understand why, and I see there are different opinions, something to do with "flashback" and "pop". Maybe someone can explain. But yes.... we had the opportunity to oxy-acetylene at a very young age and without incidence, despite it being a school with kids running around of various intelligence levels.... kind of surprising now that I look back at it.

The acetylene goes bang pretty nicely just with the relatively low oxygen concentration in air thus it's more important to turn that off first or it can build up. Acetylene is very slightly lighter than air so it tends to head up to the roof of a building and will quite happily build up and then sudden ignition takes place. Ka-boom.

Money shot at 4:03 but worth watching the whole thing.

[tooki]

They're still vastly outnumbered by the sheer masses of Americans who don't know that Switzerland and Sweden are different things. I couldn't begin to tell you how many times I've been asked "Oh!! You lived in Switzerland?? How's your Swedish?!" My usual reply is that since I've never been to Sweden, I only know what I learned from the Ikea catalog…

It's lucky that Swaziland changed its name this year then...   "Mom, I went to get the money out of the Swiss bank and it's really hot here, there's this weird black and white striped horse wandering down the street, there's a heck of a lot of black folks here, even more than in Baltimore, and that Swedish language course I took is useless, nobody understands a word I say!"

Indeed!

What is hilarious to me is the spelling of the new name, which itself is a legitimate word in their language, but looks like a turn-of-the-millennium dot-com-bubble web startup!

As for language courses, something that really trips up nearly all immigrants here is that the local language (Swiss German) is sufficiently different from standard German as to render their German classes useless. They arrive here, confident that they've learned enough to get by (and indeed in Germany it would be), and instead encounter a language that is incomprehensible, and which is hard to learn because everyone will instantly switch to standard German or English for you.


P.S. How'd you remember that I used to live in Baltimore? (Fuuuuuck do I miss Maryland crabs, and awesome Korean food, and good sushi, and Royal Farms chicken…)

[bd139]

Indeed. All I know to say is: Wo ist die biberfladen und apfelkuchen! (and that's probably wrong) 

[M4trix]

Polish oxygen-acetylene  recoilless cannon.

https://youtu.be/kLwvWgaixpI

 

[Cerebus]

As for language courses, something that really trips up nearly all immigrants here is that the local language (Swiss German) is sufficiently different from standard German as to render their German classes useless. They arrive here, confident that they've learned enough to get by (and indeed in Germany it would be), and instead encounter a language that is incomprehensible, and which is hard to learn because everyone will instantly switch to standard German or English for you.

A friend of mine at University was an Army Brat, and as a young child lived in Germany and quite naturally became quite a fluent speaker of Hochdeutsch.  Her father was an Army lawyer, and this entailed quite a lot of extended trips to Switzerland. She says, as a small child, she could never understand why the Swiss couldn't talk properly. Clearly it left an impression because, as an adult, she used to say "Schweizerdeutsch!" as if she was simultaneously spitting and naming the most reviled politician you can think of.

P.S. How'd you remember that I used to live in Baltimore? (Fuuuuuck do I miss Maryland crabs, and awesome Korean food, and good sushi, and Royal Farms chicken…)

I didn't, I don't think I did anyway. I just named the blackest US city that I knew of.

[tkamiya]

I think we can all sit back and criticize this particular situation.  But many of us, at some point, have done stupid things, and scared ourselves beyond bathroom break as we learned more.


I am a licensed electrician (my license is from Japan and I was formally trained), and I'm often amazed how home owners casually do things that are quite dangerous.  Some people are just oblivious.  On hobby front, for me, is a high voltage.  Luckily, the shock I received was strong enough to give me quite a scare but not enough to kill me.  It's easy to overplay your hands when you don't know any better.  Often times, it's more important to know what NOT to do, rather than what to do.  A good idea may have a good reason why it's not done that way.....

[IanB]

Yes. I good working assumption is that everything you see being done a certain way is most likely done that way for a reason.

Similarly, every part you find in a product or installation was also put there for a reason.

[amyk]

As someone who has argon 7L (for welding) and a divers bottle(s) I have a respect for the bottles and storage even being inert gases there still a bomb/rocket if not handled correctly, 300psi can do a lot of damage

Its sad that he died leaving behind his daughter, a little or no knowledge is a dangerous thing

Especially now with the Internet you can safely look at all sorts of stuff from the comfort of your own home, including cylinders turning into rockets and various explosions of different gases.

Lots of videos of acetylene explosions too, but unfortunately I couldn't find one where it's not being explicitly ignited.

[NiHaoMike]

I think the Mythbusters would have some fun trying to replicate the results. That should help answer the question of how explosive acetylene is under pressure.

[vk6zgo]

What a muppet.

I use to play with carbide crystals when I was a kid. As a little vandal, I used to put them in the dog crap bins, pour in some water, wait a bit and fire a roman candle at it. This taught me that acetylene was not to be fucked with. On one occasion it blew the metal support clear out of the ground. When you see the people doing it with barrels, imagine the end was closed. And that wasn't even pressurised!   

Did you live in a mining town?
When I was a kid, my Uncle & Grandfather had a smallish Gold mine in Wiluna, West Oz.
They always used "carbide lamps" when they went underground, & I still remember the harsh light & distinctive smell of them.

My Dad was brought up in a mining area, & in his day, the kids were bloody little rogues.
One of their "pranks" was putting carbide & water in an old fashioned lemonade bottle which had a glass marble inside which sealed the bottle neck.

The marble would seal the rising gas pressure up to a point, giving the kids time to clear the area prior to it going bang in a big way.

They got into trouble for rolling one of these under the school when the teacher was having a refreshing nip of brandy during break time!
It's a wonder that didn't kill themselves or end up in prison!

[vk6zgo]

Who's told you that rubbish?

Let's quash that particular BS right now though, a link, to a government page:

https://www.gov.uk/buying-carrying-knives

Heh, yyyyeah… Americans have lots and lots of crazy misconceptions about the Old World, both positive and negative.

(I'm an American living in Europe. I have had to explain to people in USA that no, I don't pay 60% income taxes. No, preservatives and food coloring and other additives aren't actually categorically banned here. No, there aren't death panels deciding who gets healthcare. No, there aren't cows hanging out on my street in the city. No, not everyone in Europe is fancy and erudite, every place has its own equivalents to white trash and hood rats. No, there actually is McDonald's here, and it's popular. And yes, they DO have cheddar cheese in England. Funny, that…  And no, not everyone in Switzerland is filthy rich!)

Nooo, we can get Cheddar here in England? All this time I've been smuggling Cheddar in from Belgium and nobody told me?

Seriously though, some of the stories I've been told by Americans about my own country, I don't know if I should laugh or cry, one of my favourites came from my partner who used to work in a London hotel, a sweet American couple wanted to know if she could book them a taxi to Edinburgh so they could have afternoon tea at the castle and be back for their dinner that eveningel.

It sort of works the other way round, too.

Many years ago along with a couple of other "Boys from Oz", I hired a car on Southampton, UK.
We proceeded in normal Australian style to put 300 miles "on the clock" over the weekend.

When we returned it, the manager refused to believe the speedo reading & wrote it down as a faulty unit
on the log.

[Monkeh]

Who's told you that rubbish?

Let's quash that particular BS right now though, a link, to a government page:

https://www.gov.uk/buying-carrying-knives

Heh, yyyyeah… Americans have lots and lots of crazy misconceptions about the Old World, both positive and negative.

(I'm an American living in Europe. I have had to explain to people in USA that no, I don't pay 60% income taxes. No, preservatives and food coloring and other additives aren't actually categorically banned here. No, there aren't death panels deciding who gets healthcare. No, there aren't cows hanging out on my street in the city. No, not everyone in Europe is fancy and erudite, every place has its own equivalents to white trash and hood rats. No, there actually is McDonald's here, and it's popular. And yes, they DO have cheddar cheese in England. Funny, that…  And no, not everyone in Switzerland is filthy rich!)

Nooo, we can get Cheddar here in England? All this time I've been smuggling Cheddar in from Belgium and nobody told me?

Seriously though, some of the stories I've been told by Americans about my own country, I don't know if I should laugh or cry, one of my favourites came from my partner who used to work in a London hotel, a sweet American couple wanted to know if she could book them a taxi to Edinburgh so they could have afternoon tea at the castle and be back for their dinner that eveningel.

It sort of works the other way round, too.

Many years ago along with a couple of other "Boys from Oz", I hired a car on Southampton, UK.
We proceeded in normal Australian style to put 300 miles "on the clock" over the weekend.

When we returned it, the manager refused to believe the speedo reading & wrote it down as a faulty unit
on the log.

She mustn't get around, 300 miles in a day is nothing but a moderate trip even in the UK.

[vk6zgo]

Who's told you that rubbish?

Let's quash that particular BS right now though, a link, to a government page:

https://www.gov.uk/buying-carrying-knives

Heh, yyyyeah… Americans have lots and lots of crazy misconceptions about the Old World, both positive and negative.

(I'm an American living in Europe. I have had to explain to people in USA that no, I don't pay 60% income taxes. No, preservatives and food coloring and other additives aren't actually categorically banned here. No, there aren't death panels deciding who gets healthcare. No, there aren't cows hanging out on my street in the city. No, not everyone in Europe is fancy and erudite, every place has its own equivalents to white trash and hood rats. No, there actually is McDonald's here, and it's popular. And yes, they DO have cheddar cheese in England. Funny, that…  And no, not everyone in Switzerland is filthy rich!)

Nooo, we can get Cheddar here in England? All this time I've been smuggling Cheddar in from Belgium and nobody told me?

Seriously though, some of the stories I've been told by Americans about my own country, I don't know if I should laugh or cry, one of my favourites came from my partner who used to work in a London hotel, a sweet American couple wanted to know if she could book them a taxi to Edinburgh so they could have afternoon tea at the castle and be back for their dinner that eveningel.

It sort of works the other way round, too.

Many years ago along with a couple of other "Boys from Oz", I hired a car on Southampton, UK.
We proceeded in normal Australian style to put 300 miles "on the clock" over the weekend.

When we returned it, the manager refused to believe the speedo reading & wrote it down as a faulty unit
on the log.

She mustn't get around, 300 miles in a day is nothing but a moderate trip even in the UK.

He was adamant!
Of course, this was back in the 1970s--- people probably get around by car a lot more now.
In those days, they seemed to just keep their car "as a pet", only taking it out on weekends.

Most travel was by public transport, with long trips usually train or coach.
People would take a Sunday drive from SOTON to Bournemouth, get stuck in an almost endless traffic jam
from about halfway through the New Forest, see about 5 minutes of their destination, & get stuck into the same thing on the return trip.

I asked, "Why don't you go to London, it'll take about the same time by the Motorway on Sunday?"
The dour answer was usually:- "London's very overrated".

[bd139]

What a muppet.

I use to play with carbide crystals when I was a kid. As a little vandal, I used to put them in the dog crap bins, pour in some water, wait a bit and fire a roman candle at it. This taught me that acetylene was not to be fucked with. On one occasion it blew the metal support clear out of the ground. When you see the people doing it with barrels, imagine the end was closed. And that wasn't even pressurised!   

Did you live in a mining town?
When I was a kid, my Uncle & Grandfather had a smallish Gold mine in Wiluna, West Oz.
They always used "carbide lamps" when they went underground, & I still remember the harsh light & distinctive smell of them.

My Dad was brought up in a mining area, & in his day, the kids were bloody little rogues.
One of their "pranks" was putting carbide & water in an old fashioned lemonade bottle which had a glass marble inside which sealed the bottle neck.

The marble would seal the rising gas pressure up to a point, giving the kids time to clear the area prior to it going bang in a big way.

They got into trouble for rolling one of these under the school when the teacher was having a refreshing nip of brandy during break time!
It's a wonder that didn't kill themselves or end up in prison!

Not a mining town. A friend’s father was into collecting mining lamps and we nicked his carbide stash. Also found the local outdoors store (army and navy surplus) at the time stocked it for cavers. Could buy a cool Kg of it for £2.

I would have probably hung out with your dad

[tooki]

Indeed. All I know to say is: Wo ist die biberfladen und apfelkuchen! (and that's probably wrong) 

Or in (Zurich dialect) Swiss German: Biberli und Öpfelchüechli! 

As for language courses, something that really trips up nearly all immigrants here is that the local language (Swiss German) is sufficiently different from standard German as to render their German classes useless. They arrive here, confident that they've learned enough to get by (and indeed in Germany it would be), and instead encounter a language that is incomprehensible, and which is hard to learn because everyone will instantly switch to standard German or English for you.

A friend of mine at University was an Army Brat, and as a young child lived in Germany and quite naturally became quite a fluent speaker of Hochdeutsch.  Her father was an Army lawyer, and this entailed quite a lot of extended trips to Switzerland. She says, as a small child, she could never understand why the Swiss couldn't talk properly. Clearly it left an impression because, as an adult, she used to say "Schweizerdeutsch!" as if she was simultaneously spitting and naming the most reviled politician you can think of.

Heheheh I believe it! I think that to Germans, Swiss German is looked upon as something rather provincial, like the Appalachian dialect of English is in USA! 

P.S. How'd you remember that I used to live in Baltimore? (Fuuuuuck do I miss Maryland crabs, and awesome Korean food, and good sushi, and Royal Farms chicken…)

I didn't, I don't think I did anyway. I just named the blackest US city that I knew of.

And you'd be close: of major cities, only Detroit has a higher % of black residents (and appreciably higher, at that!). Balto is a great city though. I love that it's a place that celebrates its dirty underbelly, rather than pretending it doesn't exist, like other places do. It has a certain whimsical, don't-take-yourself-too-seriously nature that most places don't have. (Washington DC, which Balto lives in the shadow of, takes itself more than seriously enough for both cities…)

[bd139]

Or in (Zurich dialect) Swiss German: Biberli und Öpfelchüechli! 

See I failed already