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Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
Is there any danger of an explosion from the oxygen combining with steel tubing when using compressed AIR at 2000-2500 psi?
I have heard there is a danger of the oxygen igniting the carbon in steel when compressing PURE OXYGEN over 2500 psi. Does anyone have any information?
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
Who cares about the carbon? Iron will burn in pure oxygen at ordinary pressures.
However, if you don't get it hot enough to start a fire you should be OK. A badly designed piston or bearing might get hot enough to start the fire and then the rest of it will burn. I have seen bits of what was left of steel gas cylinders and regulators after an oxygen assisted fire. I wouldn't want to be there. If you want to liquefy air for kicks and giggles, strip the oxygen out first and use the nitrogen.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
I would love to get rid of the O2 first. I'm trying to see if I can get a nitrogen membrane cheaply, but new ones go for over $2000, which is beyond my "play" budget. Any suggestions how to burn the O2 without getting too crazy? I'm planning on a flow of 3 scfm.
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
Almost anything will burn with oxygen, the trick is to pick something usable.
In order to burn, you must have some residual oxygen concentration. I would guess that a) different fuels burn to different concentrations and b) that sort of information is not well documented anywhere. So any burning process is not going to strip oxygen, just reduce the concentration.
Seperating the oxide from your nitorgen stream is also an consideration.
Hydrogen is possibly ideal for the seperating issue, you just condense the water. You can get it from metal+acid, electrolysis, or delivered in a red-painted cylinder. The third is expensive, the first two are impractical for 3cfm.
Any carbon bearing fuel will leave you with CO2, which is easy to strip with NaOH and, as the oxygen concentration goes down, CO, which if wikipedia is to be believed will dissolve in all sorts of things like alcohol and acetic acid. Hydrocarbon fuels are available dirt cheap in great variety, take your pick. Carbohydrate fuels will also produce the same products.
Damp finely divided iron, or wire wool, will absorb oxygen by rusting, but at what rate per surface area? That is also very cheap and readily obtainable.
Alkaline pyrogallol is, I have heard, available as a photographic developer chemical. But then that's getting expensive again for the volumes you'd need.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
Dr. Slack wrote ...
Alkaline pyrogallol is, I have heard, available as a photographic developer chemical. But then that's getting expensive again for the volumes you'd need.
I don't think the damp steel wool will remove enough for my flow rate. I've read about pyrogallol from other threads, but this is toxic and I believe it forms CO, which I don't want to be around. As you mentioned, it is very expensive.
Registered Member #49
Joined: Thu Feb 09 2006, 04:05AM
Location: Bigass Pile of Penguins
Posts: 362
What diameter? There is a critical diameter at which heat lost to the tube walls will outpace the heat of combustion - in that case it doesn't matter how desirable the oxygen finds the steel.
Same phenomenon that prevents oxy-anything torches from melting/flashing back. Also one of the primary obstacles to microturbine generators.
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oxygen and steel under pressure
