VSEPR_VOID
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The use of Pipes and Fittings for Super Critical Gas Storage
In the video linked bellow Cody from Cody's Lab, whom I am sure we are all familiar with  , constructed and tests a container made of metal pipe fittings for storing carbon dioxide. I wonder if any users here would find such a
thing useful. Perhaps other reagents commonly gaseous at room temperature could be stored in this manor. I imagine amateur chemists investing in a one
time purchase of liquid N2 for the purposes of liquefying/ freezing O2, Cl2, N02, CO2, CO, or NO2, then placing them in one of these canisters for
storage. The gas could then be released for various retirements at their convince. Imagine no longer having to construct elaborate gas generation and
drying apparatuses.
Some safety issues should be considered and discussed. For instance the maximum safe internal pressure should be found for such a device. In the video
Cody placed a quarter pound (.113 Kg) of dry ice into his canister of unknown volume. I imagine that the steel/aluminium used in construction should
be thick. The device should not be fully filled, and the container should be purged with the gas being used, to prevent contamination with water of
atmospheric gasses.
If they are safe perhaps they could even be safely traded or sold online among us. Some member with the correct experience and equipment being charged
with their construction in tern for money or chemicals.
I recall how divers often incorporate metal fail safe disks into their tank, and as a side note so do autoclaves. Maybe an equivalent could be added
to Cody's design to prevent explosion. At the worst case scenario, they would just be stored outside, underground, with a tubing running into the lab
with an electric motor to turn the regulator.
https://www.youtube.com/watch?v=rPxPyD5jSR4
The original video
[Edited on 29-10-2017 by VSEPR_VOID]
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Melgar
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You'd think it'd be easier and safer, and probably cheaper too, to just buy a tank that's actually rated for what you plan to use it to store, no? I
pulled up Craigslist, and there are a whole bunch of compressed gas tanks available locally for under $100. For CO2 (the easiest gas to store, by
quite a lot) there are a lot of small ones available cheap, for paintball guns, home brewing, soda stream bottles, and stuff like that. I believe
that to be rated for CO2, it has to be able to withstand 1000 psi, at least.
Granted, if you want to take your chances, you could build a huge-ass pipe bomb and fill it with dry ice, but then if you wanted to go to any of those
places that refill tanks, they'd take one look at your device and run for cover. Of course, if you had a legitimate tank, you COULD get it filled up
at those places.
Incidentally, in India and Pakistan, a lot of small vehicles run on natural gas, and they can fill up their tanks at special filling stations for
natural gas. There's usually a three-stage filling process, where it will pump at one pressure until the flow rate slows, then go to a higher
pressure, until the tank reaches that pressure too, then go up to the highest pressure, and pump until it reaches the limit for that. Because people
are poor and/or cheap there, instead of using expensive tanks rated for natural gas, they'll just use cheap tanks rated for propane. Then when they
fill up, they just know that they have to shut it off before it pumps at the highest pressure, because their tank isn't rated for that. Sometimes
they don't catch it in time though. Since you seem to like Youtube, here's what happens:
https://www.youtube.com/watch?v=zBS4Q1aBHu0
The first step in the process of learning something is admitting that you don't know it already.
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VSEPR_VOID
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Good points but you would not take it to a place for refilling tanks. The liquid/solid substance would be placed inside. The substance would become
super critical during storage.
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battoussai114
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I'm not sure if Ben from AppliedScience uses this board, he would be able to give some good insight as he has used pipe fittings to build a
supercritical drying chamber to make aerogel. Later he moved to a custom machined chamber but I think it was for ease of use. So your idea is
possible.
Some reading/watching material: http://benkrasnow.blogspot.com.br/search?q=supercritical
Just stay safe okay. Ben has a degree in Mec. Engineering and is probably above average in acessing the risks of doing a build like that.
Batoussai.
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Fulmen
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Designing pressure vessels isn't rocket science, but it does require a fair bit of engineering skills to do so safely. I cannot recommend
experimenting with this unless you're willing to read up on a lot of material science and engineering.
Storing gases in the supercritical state won't magically increase storage density (when pressure is factored in), and many gasses are in fact
supercritical at normal storage conditions. Nitrogen has a critical temperature of -150°C and 35bar, so it's routinely stored as a supercritical
fluid.
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Melgar
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Quote: Originally posted by VSEPR_VOID  | | Good points but you would not take it to a place for refilling tanks. The liquid/solid substance would be placed inside. The substance would become
super critical during storage. |
Ah. Then, in that case, it's meant for use as something other than a tank, I assume. For CO2 and N2, it's much more efficient to transfer the
supercritical liquid tank-to-tank, under pressure, than it is to remove it from that pressure first. When you remove it, you're actually using about
twice as much, half of which boils away to cool down the other half. So if you wanted a tank that you could economically get refilled, you'd still be
better off with a real tank. You'd just need to know what local places you'd be able to fill it at.
Dry ice might be an exception due to economies of scale, and the fact that dry ice can be stored a rather long time as a solid, under
atmospheric pressure. This isn't true of any other cryogenic gas that I'm aware of.
The first step in the process of learning something is admitting that you don't know it already.
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VSEPR_VOID
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| Quote: Originally posted by Melgar | | Quote: Originally posted by VSEPR_VOID | | Good points but you would not take it to a place for refilling tanks. The liquid/solid substance would be placed inside. The substance would become
super critical during storage. |
Ah. Then, in that case, it's meant for use as something other than a tank, I assume. For CO2 and N2, it's much more efficient to transfer the
supercritical liquid tank-to-tank, under pressure, than it is to remove it from that pressure first. When you remove it, you're actually using about
twice as much, half of which boils away to cool down the other half. So if you wanted a tank that you could economically get refilled, you'd still be
better off with a real tank. You'd just need to know what local places you'd be able to fill it at.
Dry ice might be an exception due to economies of scale, and the fact that dry ice can be stored a rather long time as a solid, under
atmospheric pressure. This isn't true of any other cryogenic gas that I'm aware of. |
You misunderstand. I will list out what I mean.
1) A canister is constructed out of pipes and fittings. It has a value on one end to permit the flow of gas out.
2) Liquid nitrogen (A one time purchase) is used to liquify for freeze a gas used in the lab often enough to warrant this.
3) The now liquefied/frozen gas is poured into the container.
4) The container is sealed with the the liquid/solid inside it.
5) The container is now sealed, and as the temperature rises, the container is now under great pressure.
For example if dry ice was placed into the container the result would be super critical CO2 inside the container.
6) The container can be stored at room temperature and when desired the valve is open to release a suitable amount of its contents.
There is no need to go to a fill station, purchase a tank, or have anything filled. The exception is the purchase of the initial N2.
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Fulmen
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Actually you would get liquid CO2, not supercritical. And that's what you want if you want to store large amounts of gas in a small volume.
While possible in theory it's not doable with OTC equipment for anything but a few select gases. Regular pipe fittings are made for fairly low
pressure applications, so you would be limited to say 10-20atm of pressure. You could perhaps push 50 in some cases, but for gas storage that's not a
lot.
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VSEPR_VOID
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What about steel pipes and fitting such as those shown in the video linked in my original post?
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Fulmen
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I have to admit I know very little about US pipe standards, but after a bit of research it looks doable after all. From what I could find schedule 40
steel pipe is rated for 1500-3000psi (you'll have to do your own research of course), assuming the threads and fittings have the same strength it
should be possible to make decent pressure vessels from it.
But it's not like you can pour any liquefied gas into a container nilly willy. You'll have to check the pressure needed to keep it liquefied at room
temperature, many gases will require pressures far beyond sch40 ratings. And many can't be liquefied at all at room temperature, in that case you
would have to use a pressure gauge to ensure you don't exceed safe pressures. The storage density for pressurized gases (supercritical or not) is low
compared to liquefied gas, so it might not be worth the effort.
Lastly you will have to consider the effects of cryogenic temperatures when it comes to material strength. Metals become brittle at low temperatures ,
so even though the pipe can withstand the pressures at RT it might not do so at lower temperatures.
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wg48
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Ideally any home made pressure vessel would be tested at 1.5x its working pressure. If its going to be heated I would test it at 2x its working
pressure and perform the test at the maximum working temperature. Water or oil must be used for test so as to avoid a compressed gas explosion
If you are relying solely on calculation and correctly known material strengths your betting getting it correct against a nasty accident.
For the test you could use the parts from an old hydraulic jack, small (a few mm) diameter tubing and a pressure gauge. Use the smallest diameter
pipe you can readily obtain fittings for. Make connections to the parts of the hydraulic jack with threaded fittings. You can also use the piping and
fittings from the hydraulic brakes of a scrapped car.
I found a free hydraulic tester savaging in dumpster. Its used to test heating radiators. It only rated to 60bar. I think I can push it to 90bar so
it should be good for testing room temperature CO2 a vessels. I am still hunting for a free hydraulic jack I may have to buy one.
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Melgar
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| Quote: Originally posted by VSEPR_VOID | You misunderstand. I will list out what I mean.
1) A canister is constructed out of pipes and fittings. It has a value on one end to permit the flow of gas out.
2) Liquid nitrogen (A one time purchase) is used to liquify for freeze a gas used in the lab often enough to warrant this.
3) The now liquefied/frozen gas is poured into the container.
4) The container is sealed with the the liquid/solid inside it.
5) The container is now sealed, and as the temperature rises, the container is now under great pressure.
For example if dry ice was placed into the container the result would be super critical CO2 inside the container.
6) The container can be stored at room temperature and when desired the valve is open to release a suitable amount of its contents.
There is no need to go to a fill station, purchase a tank, or have anything filled. The exception is the purchase of the initial N2.
|
You realize that the amount of your initial purchase won't last forever, correct? Eventually, you'd have to refill it, and the thing that you're
describing is also how a regular liquified-gas pressurized tank works. The only advantage I can think of for what you're describing is that it can be
refilled using solid dry ice, though it's not particularly difficult to get canisters of CO2 anyway.
[Edited on 10/31/17 by Melgar]
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SWIM
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I can see your point about this being useful for some gasses.
Although I haven't shopped for them I assume a guy like me with no lab affiliation would have a hard time getting a pressurized tank of chlorine or
HBr (although I don't think HBr in an iron pipe would be a great long term storage idea).
Even Ammonia, which is as common as dirt on American farms as a liquid, might be hard to get in a small tank at reasonable prices in an area as
suburban as mine. NO2? If I asked for something like that under pressure at one of the local chemical suppliers not only would I not get it, but
they'd probably be a lot less flexible about selling me things in the future because their suspicions would be aroused.
I'll be watching your posts on this with interest (please do post what you find out. That way others who want to try this won't have to start from
scratch)
One thing that might be obvious to you but I bring it up just to be sure: Don't forget the zinc! Standard plumbing fittings I am familiar with in the
US are galvanized, and that zinc might react with some of the gasses you want to store.
Chlorine, ammonia, would these be a problem?
I'd also be worried about NO2 in a zinc lined container.
Easy enough to dissolve the zinc off the inside before you fill the tank, but It's the kind of thing you really wouldn't want to forget.
There's also the metal fatigue question. Standard plumbing might be rated for huge overpressure, but will it take repeated cycles of it without coming
apart like an early 50s BOAC Comet?
Those purpose built pressure vessels may have alloys which withstand repeated fillings much better, and I believe even those have ratings for how many
times they're used before they get some sort of re-testing.
I have heard that the threads on the pipes are the weak point on pipe bombs and that one made from a large elbow bend with the ends closed off by
threaded metal plugs is supposed to generate more pressure before they blow, and hence a bigger bang, than a straight pipe with end caps. (the
Tsarnaev brothers used this design for the small bombs they threw at their pursuers). If this is accurate, it might serve as a model for a stronger
pipe fitting based storage tank.
Probably somebody here who loves the science of explosions wold know if that last comment is actually true or not, even though they don't make steel
cased bombs themselves.
(I doubt any responsible person would. As far as I know their sole purpose is mayhem.)
[Edited on 31-10-2017 by SWIM]
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VSEPR_VOID
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Thats some interesting information. It looks as if pipe bomb design will have some peaceful applications.
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