How gas bottles work

[outofthefire]

I've cut up loads of bottles, propane, co2 and argon, but earlier I realised i've no idea how they work. Do they create a vacuum in them first or is the air inside just compressed and allowed to mix with it and why do co2 and argon bottles have a copper tube right down to the bottom of the bottle and propane doesn't.

 

[rtbcomp]

Bottles with a tube down to the bottom deliver liquid "gas". The most common application is the propane bottles used on fork-lifts. The bottles are mounted on their side so a bent (or angled) dip-tube will be used, there will be a marking on the outside to indicate the position of the dip-tube. Propane & butane bottles used for cookers, heaters &c &c have no dip tube and the liquid boils off to deliver gaseous gas, the bottles should be used upright.

I've never seen a CO2 bottle with a dip-tube (and I've cut about half a dozen), and I can't think why an argon bottle would need a dip tube because argon is stored as gas.

I suspect new bottles will be purged with the gas they'll be containing before filling, this is particularly important with flammable gasses as an explosive mixture could be achieved as the bottle empties.

 

[CKJDJK]

CO2 fire extinguishers usually have a dip tube. If using with mig then invert it so you draw off gas and not liquid into your regulator.

 

[outofthefire]

I've never seen a CO2 bottle with a dip-tube (and I've cut about half a dozen), and I can't think why an argon bottle would need a dip tube because argon is stored as gas.

Thinking about it, the co2 bottle was a fire extinguisher, but I cut up a large argon/co2 bottle last and that had a tube.

 

[AndyStobbs]

What are you doing cutting all these bottles up? I've spent a fortune on bottle deposits. Argon/co2 is going to be the next one I have to pay out for.

 

[HMB]

I've cut up loads of bottles, propane, co2 and argon, but earlier I realised i've no idea how they work. Do they create a vacuum in them first or is the air inside just compressed and allowed to mix with it and why do co2 and argon bottles have a copper tube right down to the bottom of the bottle and propane doesn't.

No vacuum (as such) filled to relevant pressure with gas, shipped on. Acetylene is stored as a liquid in a foam shock absorber.

 

[outofthefire]

What are you doing cutting all these bottles up? I've spent a fortune on bottle deposits. Argon/co2 is going to be the next one I have to pay out for.

They're usually scrap, just because you have an empty bottle doesn't mean you can just swap it for a full one.

 

[colnerov]

Acetylene is stored as a liquid in a foam shock absorber.

HI, Acetylene as a gas is unstable and so is stored in Acetone, as you say in a shock absorber in the cylinder. The bottles should not be used on their side as the Acetone is burnt in the flame and this can create a void in the bottle if it has sustained an impact. The shell of the bottle recovers a certain amount afterwards but the foam doesn't. I am recalling this from my Hazchem course when I worked for BOC. We were told when picking up returns to feel the bottle for temperature to check there wasn't a fire in the bottle. One of the "war" stories we were told was of a bottle stood on a rubber mat gently rocking from side to side because the pressure release valve in the bottom of the bottle was blowing off excess pressure. He refused the bottle and reported it and was subsequently sent on his way by the fire brigade with his truck load of cylinders while they dealt with it.

Colin

 

[colnerov]

They're usually scrap, just because you have an empty bottle doesn't mean you can just swap it for a full one.

Hi, gas cylinders have a five year service life and are checked and certified every year. That's what all the codings are for round the top of the cylinder. I used to work for BOC and I can remember once that a pallet load of re certified Oxygen cylinders had just been filled and when they came to disconnect they found that all the valves hadn't been tightened down. We were all moved away from the area while that was dealt with.

Colin

 

[Bill Edwards]

Apparently when an acetylene cylinder vibrates and feels warm...

That's the cue to run faster than you've ever run before. Sometimes it can go on for 2 minutes before it goes bang, other times hours.
Supposedly a hard knock can set them going, which is why I cringe at the way some people handle them.