Author Topic: Acetylene things your mother never mentioned !  (Read 15424 times)

Offline PTsideshow

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Acetylene things your mother never mentioned !
« on: October 16, 2010, 05:21:53 PM »
Since the subject has come up in another thread. I thought this would be a good time to put this out here. Now This is US based information as per our regulations regarding the cylinders for compressed gases.

The material inside the acetylene cylinder has changed over the years. There was a short time span 3 to 5 years that asbestos was tried but, they stopped using it. No the urban legend is that there may be some cylinders out there still with asbestos. Very little chance, as the regulations required by D.O.T.(Department of Transportation) and C.G.A.(Compressed Gas Association) translate (records) are great. they were pulled out of service as thier inspections and retests came up.

What you will find in most is AGAMASSAM a porous substrate that fills the cylinder which inturn is filled with a liquid that acetylene will dissolve in.
This will be one of two liquid solvents, either the well known ACETONE or DMF (DIMETHYL FORMAMIDE) When the cylinders are inspected and tested if need be the liquid is topped off.


Is a acetylene cylinder cut in half showing the Agamassan

The above is needed because of the fact that acetylene, is a very unstable gas when compressed in its gaseous state above 15 psig. Therefore it can't be held in a hollow cylinder in a high pressure state, as other gases can.
It can be dissolved in to the solvents mentioned and then pumped into the cylinder to be stored and shipped.

There is a maximum rate that acetylene can be dissolved into and with drawn from a cylinder.
There was a recent change in the accepted rates from the old 1/7 rule to 1/15 continuous flow or 1/10 intermittent

link to post for the link


Here are the US two smallest acetylene cylinders
The larger one is a B cylinder 33cuft  (Bus as at one time it was the sized used for the lights on buses and trucks) And the smaller one is an MC with adapter 8 cuft (Motor cycle used for lights on motor cycles before batteries. Angled valve is so it could be clamped to the angled front cross bar)

Fusible plug on the bottom of a B sized cylinder, I do also have a B cylinder with out any fusible plugs anywhere.

Is the location of the fusible plugs on a lease cylinder another one across the valve and two more on the bottom.

By the way an acetylene cylinder is a low pressure cylinder 225psig The fusible plugs melt at 212'F (100'C)

It has a low explosive mix limits in air% 2.5%
It has a garlic type odor added to it to help identify leaks
 
:coffee: I have edited it to add a couple of things I forgot the first time :coffee:

If the cylinder is laid on it side, you have to let the cylinder stand up right for at least the minimum time it was on it side so the solvent holding acetylene can go back into the monolithic fill material in the cylinder. There are all kinds of times suggested, 45 minutes is generally a time line before you use it.

This is so the solvent isn't carried over with the acetylene gas into the hoses and the regulator which can be damaged by it.

What pressure to stop using an acetylene cylinder, again the recommend pressure is around 50psig but the general rule has been at a lower flow rate you can use it down to 25 psig. Again this has to do with the separation out of the solvent of the acetylene gas. At lower cylinder pressures, since there is a little open space at the top of the cylinder. It tends to carry over the solvent which then can result in liquid greenish flames dripping from the torch tip or spurting of the flame.

That is why you need R,RM or T grade hoses for use with acetylene

And when transporting a cylinder of acetylene it shouldn't be inside of an enclosed van or car. Since the explosive mixture is so low, the slightest spark can set it off. As all the vid's on  U tube show the results in a lapse in judgment.

Ask for and carry in your vehicle the MSDS for any and all compressed gas cylinders you carry or use. As some local governments have local ordinances, that give them power to fine you if you don't have the D.O.T. paper work in the vehicle.

On one of the welding forums somebody got nailed $50.00 each cylinder, they sit outside the LWS and get people coming out of the drive. They make the rounds of all the LWS, then come back in a month or so and start all over again

Never place the cylinder in a bucket of hot water, or water on a hot plate to get the gas moving in winter in an unheated shop.

And finally Acetylides  of heavy metals are easily formed by reaction of acetylene with the metal ions. Several, e.g., silver acetylide and copper acetylide, are powerful and very dangerous explosives. Copper acetylide is also formed by reacting acetylene with metallic copper or its alloys; these materials are therefore unsuitable for installations for handling acetylene.
Copper Acetylide

« Last Edit: October 17, 2010, 07:25:56 AM by PTsideshow »
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Offline crabsign69

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Re: Acetylene things your mother never mentioned !
« Reply #1 on: October 16, 2010, 10:27:38 PM »
i did not know this stuff  great info

Offline PTsideshow

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Re: Acetylene things your mother never mentioned !
« Reply #2 on: October 17, 2010, 07:30:14 AM »
Glad It was something useful. :thumbup:
Upon reading the post again, I found that I had left out some other important information! So I edited it. Scroll down and look for the :coffee: towards the end of the post. It is below those.
"The internet just a figment, of my imagination!' 
 
 There are only 3 things I can't do!"
Raise the Dead!
        Walk on water!
                 Fix a broken heart!
and I'm working on the first two!
glen