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Acetylene Safety


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  #21  
Old 10-25-2009, 04:09:53 PM
jdunmyer jdunmyer is offline
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Default Re: Acetylene Safety

Quote:
I have one of the mini oxy acetylene rigs. It's tempting to make up transfer lines to fill them from large bottles, but my better judgement tells me not to do it. I realize the lines would have to be oil free and purged, what other dangers?
I think that this would be a Bad Idea, but can't really explain why. Free acetylene (not absorbed in the tank's liquid) is very unstable, to the point of being able to be set off by mechanical shock.

Many years ago, there was a fella near here who made acetylene for welding use. Although I don't know the whole story, old-timers still talk about the explosion. I'm guessing that the he was trying to bottle it for sale, as that was part of his business, but I'm not sure.
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Old 10-25-2009, 04:45:29 PM
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Default Re: Acetylene Safety

Look at it this way, have you ever seen a professional gas company hauling them laying down?
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  #23  
Old 10-25-2009, 05:21:23 PM
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Bill Geyer Bill Geyer is offline
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Default Re: Acetylene Safety

Blacksmith shops used to have acetylene generators, a tank with water and calcium carbide. Some farms had them to run cook stoves, and lights. It wasn't necessary to stand the tanks up for transport or strap kids in a seat till the roads became full of people driving around like idiots Lucky anyone is left alive with all the lead, asbestos and other dangers.
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  #24  
Old 10-25-2009, 07:03:08 PM
jdunmyer jdunmyer is offline
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Default Re: Acetylene Safety

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Blacksmith shops used to have acetylene generators, a tank with water and calcium carbide. Some farms had them to run cook stoves, and lights. It wasn't necessary to stand the tanks up for transport or strap kids in a seat till the roads became full of people driving around like idiots
Bill,
Those gas generators ran at low pressure. The problem with free acetylene is when it's pressurized to more than about 15Psi. That's why the guages usually have a "red zone" above that pressure.
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  #25  
Old 10-25-2009, 08:10:52 PM
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Default Re: Acetylene Safety

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Originally Posted by JKWidener View Post
Look at it this way, have you ever seen a professional gas company hauling them laying down?
Makes it easier to load and more importantly unload when they're all standing up versus being stacked like firewood, especially when you have a mixture of tall & short ones. Plus if you had 30-100 bottles stacked up like that it would make it nearly impossible to secure the load to keep tanks from sliding off of each other.

The shop we got ours from when I was a kid and Mom would take the old ones in for exchange, with her not being able to lift them, & me being too small at the time, the "Professionals" there would take the old one out of the trunk and put the new full one in for her. And they'd slide the spare tire up against it to keep it from rolling, as there was No "hold down" chain or strap in the trunk.

I've heard of propane torches & grills flaring up from the propane tanks being tipped while in use, but it's never been a problem with acetylene that I've ever heard of, but then I apparently live a pretty sheltered life.

Not knowing before reading any of these posts whether it was a true gas (vapor) or if it was in a liquid state in the bottles, I never would have used one laying down, but hauling, it makes no difference
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  #26  
Old 10-26-2009, 09:28:48 AM
PTSideshow PTSideshow is offline
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Default Re: Acetylene Safety

Ok to start with there are so many, statements that aren't correct out there and have become urban welding legend.

When transporting a cylinder of any size whether it is a MC (10³ft) or a B(20³ft) or a full size one. After transport and BEFORE USE a minimum of 30 minutes is recommend that the cylinder be in the upright position before connection and use.

This is to let the liquid phase of the acetone/DMF separate from the acetylene. In the upper portion of the cylinder.
The upper part of the cylinder as in the picture in the link in a previous post, showed there is only a small open area.

This is to keep the acetone from traveling into the regulator and damaging the rubber components, and contaminating the weld pool and the weld.

At the tip it will cause discoloration of the flame and spitting and sputters.

The first thing is acetylene can under certain conditions above 15psig (1bar) may spontaneously disassociate (breakdown) into it's components carbon and hydrogen. And go boom! As been stated that is why the red danger and the statements not to use it above 15psig!

Given this nature of acetylene any user would have to generate acetylene on site.

The reason a solvent is used to dissolve the acetylene is so more can be stored and transported in the cylinder. Acetone can contain up to 25 times its own volume of acetylene per atmosphere of pressure.

This gives a large increase in capacity of each cylinder.

Today, the gas is shipped and stored in metal cylinders containing acetylene, dissolved in dimethylformamide (DMF) or acetone.

Agamassan (aga) is a porous substrate used to safely absorb acetylene/solvent and thus allow the transport, storage and commercial exploitation of an otherwise unstable gas.

Here is another fable:the cylinders are filled with asbestos!
Asbestos has not been used in an acetylene cylinder since the 30's. Not saying that some are not still around but doubtful you have it. It was used by one company for a period of about five years. The Compressed Gas Association has thoroughly researched and documented what cylinder manufacturer placed what fill into a cylinder and during what time period

Another big debate is what pressure to change the cylinders out at:
The CGA handbook and most other books on acetylene and welding. Recommend that the cylinders be changed to a full one, between 50 psig and 25 psig.

At these lower pressures, the amount of solvent expelled is dependent on the solvent vapor pressures, the condition of the cylinder, and the conditions of withdrawal. The condition of the cylinder is the inside and the number of charge discharge cycles, As the solvent can be come thick with age,impurities and cycles etc.


Something else that is often stated incorrectly is that the material filling the inside of the cylinder is only part way that is incorrect. As the material fills the cylinder, but it is extremely porous. This along with the fill rate(dissolving rate into the solvent 7 hours for a full charge,this is were the 1/7 use rate comes out).

Purity of the acetylene:
Acetylene that is manufactured by the water/calcium carbide method inherently has more impurities in it. Impurities such as traces of phosphine, arsine and hydrogen sulfide. Are not routinely screened for in the acetylene produced for the non critical area of welding and cutting. The levels of contaminants are based on the calcium carbide produces information. They are not routinely tested by the producers of the gas.

A full cylinder of acetylene's pressure no matter what the size is:
225 pisg, this is a full cylinder.

They do not change the acetone out at each refill! They do add to the acetone charge.

Acetylene cylinders are considered hazardous waste materials.
They have to be cut in half or a large dia hole cutting the side.
Reuse of a acetylene cylinder for any reason is just an exercise in wasting time and effort. the material inside is very hard to get it all out. And when you have it out it is hazardous waste. And the fines for improperly disposing are high.

Oxygen and other inert compressed cylinders are a better for gongs and other uses the bottoms can be used for a metal forming stake/anvil or the smaller ones make great metal melting crucibles.
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  #27  
Old 10-26-2009, 09:45:54 AM
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Default Re: Acetylene Safety

Quote:
Originally Posted by J.B. Castagnos View Post
I have one of the mini oxy acetylene rigs. It's tempting to make up transfer lines to fill them from large bottles, but my better judgement tells me not to do it. I realize the lines would have to be oil free and purged, what other dangers?
DO NOT DO IT UNDER ANY CIRCUMSTANCES! They are special conditions as to the rates and pressures that acetylene can fill a cylinder.

The fill rate(dissolving rate into the solvent 7 hours for a full charge, is were the 1/7 use rate comes out).
Filling is done by special equipment over a 7 hour period. As the rate can't be speeded up.

As the guy that runs the LWS acetylene plant said, tell the guy to just put a gun in his mouth! His family will have more to bury. When he was asked about a diy manifold system!
see my other thread on copper acetylide.
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  #28  
Old 10-26-2009, 03:01:45 PM
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Default Re: Acetylene Safety

I don't know about the rest of you out there, but I learned a few things here....

Other than the 30 minute timeframe for standing upright after hauling, I'm assuming (dangerous, I know) that it IS OK to transport them laying down as long as you stand them up for 1/2 hour before using ???

Maybe I've just gotten lucky using them right away after hauling home, or within 10-15 minutes anyway once I got everything hooked up and ready to go again. Or was I right before in assuming that cracking the valve before hooking up the regulator helps to remedy that problem by blowing out anything that would cause problems ??

As for cutting one in half, I never would have tried that to begin with, at least not with a torch.... MAYBE with a band saw, but now knowing that you have the Hazardous material to dispose of I wouldn't even do it that way.

Refilling at home..... I didn't know that was possible..... I know they make adaptors for filling smaller propane tanks from big ones, but hadn't heard of doing so with any other gases.
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  #29  
Old 10-26-2009, 06:55:03 PM
PTSideshow PTSideshow is offline
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Default Re: Acetylene Safety

A couple of things that may be of use or interest. More local state counties are passing their own regulations on the transport of compressed gas cylinders both fuel gases and inert gas. The local reg's always supersede the federal ones.

You can check with the LWS next time you are in. And while you are in there ask them for a copy of the Material Safety Data Sheet, for each gas you are using or carrying in you vehicle. Keep them in your glove box that is the one that they will get the fine on you. If you don't have em.


glen
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  #30  
Old 04-10-2010, 09:30:11 PM
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Default Re: Acetylene Safety

I have been thinking about buying a small torch set. I am always in need of a way to cut or heat something, however it sounds to me like its almost too dangerous to have around. If i understand correctly, an acetylene cylinder can explode just from being bumped into or dropped, no spark or fire required. I drive a suburban 95% of the time, and a small car or 1/2 ton pickup the rest of the time. If i had a torch set the only place to store it is in the suburban. This also sounds like a big no no. Granted id only have the mini bottles due to a lack of a place to keep them but still, im sure thats all it takes to make a nasty explosion that would end my life.

How about a propane/oxygen torch setup? I have seen people use those before. Do those get hot enough to cut and heat well? I can weld with an arc welder so that isnt much concern. It sounds to me like propane is much safer.
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  #31  
Old 04-11-2010, 11:51:53 AM
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Default Re: acetylene safety

Well said brother.
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  #32  
Old 04-11-2010, 11:54:05 AM
ironwhacker ironwhacker is offline
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Default Re: Acetylene Safety

Last post went to the wrong place!!!
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  #33  
Old 04-11-2010, 04:23:39 PM
jdunmyer jdunmyer is offline
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Default Re: Acetylene Safety

Quote:
I have been thinking about buying a small torch set. I am always in need of a way to cut or heat something, however it sounds to me like its almost too dangerous to have around. If i understand correctly, an acetylene cylinder can explode just from being bumped into or dropped, no spark or fire required. I drive a suburban 95% of the time, and a small car or 1/2 ton pickup the rest of the time. If i had a torch set the only place to store it is in the suburban. This also sounds like a big no no. Granted id only have the mini bottles due to a lack of a place to keep them but still, im sure thats all it takes to make a nasty explosion that would end my life.
Why would you store your torch in a vehicle?

Actually, acetylene is quite safe IF USED PROPERLY. Like a lot of other things, your vehicle included. If you were to turn a non-driver loose with your 'Burb, just toss him the keys, you'd pretty much expect disaster. However, if that person gets a bit of training and then follows the rules, he'll be pretty safe, barring mishaps caused by others.

From Wikipedia:
Propane does not burn as hot as acetylene in its inner cone, and so it is rarely used for welding.[6] Propane, however, has a very high number of BTUs per cubic foot in its outer cone, and so with the right torch (injector style) can make a faster and cleaner cut than acetylene, and is much more useful for heating and bending than acetylene.

You should learn how to mount regulators on the cylinders, how to set them, and how to shut the torch down when you're done. (Hint: shut off the tank valves, then bleed down the hoses one at a time, closing the torch valves after bleeding each hose, then back off the regulator adjusting screws. Many torch users neglect this last step)
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  #34  
Old 04-11-2010, 06:43:53 PM
PTSideshow PTSideshow is offline
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Default Re: Acetylene Safety

torque454, What was stated is that
Quote:
acetylene can under certain conditions above 15psig (1bar) may spontaneously disassociate (breakdown) into it's components carbon and hydrogen. And go boom! As been stated that is why the red danger and the statements not to use it above 15psig!
Meaning that is why it isn't used at any pressure approaching 15 psig. The gas is unstable to the point that it can and does go boom. It is unstable in pure form and thus is usually handled as a solution Dissolved in acetone or DMF (Dimethyl Formamide. That way it is safe and practical to store transport it in a volume that one can use it.

Part of the problem of transporting it in an enclosed space car van, suburban, Is if there is a slight leak from the valve. As it is what is called a single seat. It is a low pressure cylinder by the CGA as to the max fill pressure. 225psig. And should only be opened 1/4 to 1/2 turn. So it can be quickly shut off.

The videos on you tube about cars and vans exploding are cases of the parties having a leak and not being able to smell it, and being smokers! Lighting up the ciggy sets off a flash bang kind of thing the cylinders in most cases do not rupture or explode. Just the accumulated gas build up. As far as I know all people in the vehicles were singed and hair burned off, had hearing loss or ringing of the ears for a while.

We had a local guy that was working on the dock of the LWS acetylene plant near Port Huron Mi. He was using another bottles safety cap trying to beat off another cylinders cap,( it was cross threaded. wrong choice of tool. Since the area pretty much smells from the additive they put in the gas. He didn't notice the slight gas leak from the one he was wacking on. He was burned on both his arms, and became what was described as instant bald over the exposed portions of his body. It sure did make great TV as the propane bottles 100 pounders were sailing over the house across the street from the plant and splashing in the Saint Mar's river, They were filmed on the refinery's closed circuit cameras.

As the cylinders depending on their size, has from one to 4 low temp 212'F melting alloy to vent the gas to the atmosphere be fore the cylinder goes boom! they are located on the top and or bottom or both the top and bottom.

Now having been a smoker for longer than I haven't smoked. I no from personal experience that the sense of smell is diminished.

I have discussed this with a number of people in the biz of generating acetylene gas. All most all the documented cases of an acetylene cylinder taking out a car/van/etc are cases were the set off point has been a smoker lighting up. The explosive mixture per cent with the atmosphere is 2.5%to80% Any point across that spread and light a match or a spark it goes off.

The DOT reg's on transporting the cylinders are clear. the practice of having regulators and torches on cylinders while on the welding rig. Are fast disappearing, mainly to the theft of the equipment, and now they are putting the bottles in cages or lockers on the trucks because of theft.

There are a number of states and localities that have extra regulations that require you to transport them standing up and chained in place. There are safe to transport and use if you follow the rules that are in place.

But throwing them in the back of a van or car trunk or even the back of a pick up to roll around, is just plain stupid. More so for the smaller sized cylinders. As they do not come with safety caps.

The MC stands for Motorcycle cylinder (lighting in the olden days, angled valve because they were clamped on the cross bar) Talk about a crotch rocket


The B stands for Bus cylinder, same as above they were used for lighting on bus and trucks and cars

The oxygen cylinders also do not have caps in the smaller cylinder. By the way the colors are not standard, and either cylinder can be any color. They "MUST" have a paper sticker on the top of the cylinder describing contents.

Both of the above photo's show the proper adapter that a full sized regulator set requires.

is what the filling in a cylinder looks like with out the solvent.

Oxygen valve double seat high pressure has to be open all the way. So the second valve seat can seat and keep the oxygen form leaking out.

And as far as filling your own smaller cylinders, if the transfer rig is made out of copper, you are asking to have your family hire one of them CSI crime scene clean up outfits! There is a reason why ALL Manifolds and piping are the black iron pipe.
As the guy at another acetylene generating plant said about it. Just put a 45 in your mouth, there will be more for your family to bury.

I will post a long post on the dangers of acetylene and copper, silver and mercury. In a bit, have to do some chores. SWMBO has called me to duty!

It is said that God looks out for fools and little children. Of lately I think he is only looking out for the children. As it seems he is taken people out of the gene pool

Here is another thread you may find of interest
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  #35  
Old 04-11-2010, 07:44:32 PM
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Default Re: Copper Acetylide an explination of DANGER

Copper Acetylide an explination of DANGER
I have been looking for some more info on it. After talking to any number of people in the welding gas supply biz and out. Or even the welding biz.
What I have found out is this.
At the local outlet the people populating the store in front and back offices. Also a couple of customers, nobody had ever heard of this danger. They all looked at me like I just stepped off a saucer parked outside.To prove me wrong they called the guy that runs their acetylene plant, more on that later.
As to manifolds for oxygen and acetylene gases. Why bother as to the extra equipment you need to meet the codes for install and room for separate storage of full and MT cylinders(different rooms) along with the segregation of the types of gases.
You need a special back flash preventer Liquid type. Regulators, valves and a host of other things.
The section of the NFPA codes are 51A
NFPA 51A
NFPA 51B
NFPA 51 design and installation of oxy/act systems
They aren't cheap for the sections. (Since I posted this they now have removed the free look at sections)

Schedule 80 black iron pipe is the rule if 3/4" or less welded joint preferred.
Rex air or Rex arc is the name of a company that installs them

Copper Acetylide is chemical compound of Acetylene gas and pure copper.
Copper acetylide can form inside pipes made of copper or an alloy with high copper content(67% copper or more), which may result in violent explosion. [1] This was found to be the cause of explosions in acetylene plants, and led to abandonment of copper as a construction material in such plants.[2] Copper acetylide can be prepared by passing acetylene gas through copper(I) chloride solution in presence of ammonia:

Since it is a case of the higher the copper content in an alloy of the piping. And in general K or L type pipe/tubing or fitting is made from scrap metals rather than virgin copper. It was thought that it could be used But the current thinking is since you don't know what the alloy percentages is in it now.DO NOT USE COPPER FOR ACETYLENE GAS
I talked to the guy who runs the local welding companies acetylene plant. What he said was "just put a gun in your mouth, your loved ones will have more to bury". He has been the Smith welding supply acetylene plant operator for 25 years.
So unless you are doing a very high volume of cutting and need it. It isn't worth the expense to have it done. The hard piped manifold system according to the code.

As a tid bit of additional info. Silver, and mercury when combined with acetylene also form Silver acetylide, Mercury acetylide. Which are not as sensitive to heat and shock as the Copper acetylide. Which is so unstable that it generally can go kaboom as it forms under the right conditions.

I have 10 or so books on welding, only one mentions it in passing in two sentences. And then moves on to other factors for manifolds.
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