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XeonTheMGPony
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Quote: Originally posted by j_sum1  | Seems to me there are a lot of dumb and hazardous ideas being thrown around in this thread. Why not throw a couple of litres of liquid chlorine in an
aluminium dive cylinder and be done with it. If you are into hazardous storage then why make it over-complicated.
I think there are only three feasible solutions to the question of Cl2 storage.
1. Store 0.2mL of liquid chlorine in a glass ampoule and bury the whole thing in acrylic for an element display.
2. Get a proper lecture cylinder of Cl2 gas. Be prepared to pay the bucks and go through proper channels.
3. Make Cl2 gas as needed, employing good lab practice. |
My favorite has all ways been the chloro Alkylie cell
two electrodes, some mercury, systolic pump, adjustable power supply, and I get free sodium hydroxide and hydrogen while at it!
Very easy to adjust the flow too
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coppercone
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I don't see how buying rated parts and putting them together to make something is dumb and hazardous
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unionised
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Rated for use with (possibly wet) chlorine?
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coppercone
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it should not be wet, but again the only material I can find, listed as compatible without any coating wizardry is hastalloy, which is expensive,
meaning this is a serious luxury.
I have a feeling that Sigma aldrich actually sells chlorine in regular stainless steel containers which have some kind of fancy coating.. they claim
stainless, and their corrosive gas regulator stations are made of Monel (which is actually incompatible with anhydrous chlorine liquid), so you are
reliant on not having any splashing.
Theoretically if you make something out of seamless hastalloy C tubing and valves for use with liquid anhydrous chlorine, it will outperform the
reliability of what Sigma is selling.
Also, if you use things like swagelok or gyrolok, you can actually do a full disassembly to completely clean out the container and do a full visual
inspection without worrying about things like weld fatigue, since there are no welds, or coating flaking, as the materials are intrinsically
compatible.
Since you are using simple pipe, you can also cut the swaged area off after a single use, and buy replacement compression fittings to reuse with the
same threads and stuff... they are also generally much more reliable with repeated use then NPT anyway, so you can be confident doing something like a
yearly visual inspection on storage cylinder integrity using a boroscope
for storage of things like Hydrogen-halogens, you also don't want welds because they offer a good area for hydrogen to diffuse into and cause metal
fatigue, because they will be inherently more porous then the seamless tubing.
If you have a hydrogen stressed weld, it can actually fail at a lower pressure then your burst disk, so the discharge of hazardous material will occur
in a different area then anticipated, I think (I would like for someone to confirm this, I am not a welding engineer but this is my understanding of
it).
I caution anyone attempting to do this to investigate the compatibility of hastalloy with anhydrous chlorine though, I am not entirely convinced it is
at this point in time, I would need to actually talk to a manufacturer.
If it requires any kind of coatings I would say no one should do this at home, just because its a complete pain, especially like coating a valve
surface, it would probably need to be reengineered to ensure the coating is not stressed.
[Edited on 26-5-2018 by coppercone]
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Panache
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i stored liquid chlorine in an ordinary reagent bottle in my ultralow freezer for years, its a very pretty colour.
So fuck the hastaloy, the inconel (how is that spelt), the making it whilst trying to use it. btw copper cone i am completely on side as per not be
running two reactions simultaneously. Everytime i have used chlorine for something it was....challenging. So you just need to befriend someone in a
biosciences lab that cycles their ultralow freezers into scrap every three years, i got mine for $500, or maybe it was $1500.
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coppercone
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How many watts is that to run? I can probobly engineer a multistage freezer, actually for a fixed load a peltier cascade might work if the insulation
is good but i dont want a jurassic park situation on my hands.. I had like 14 days no power this year.. The last shit i need is some fucking generator
fucking up
Like a well engineered one, how long does it stay cold before you have the return of the living dead on your hands?
I also suspect that a compressor cooled one would stay cold longer then peltiers because the refrigerant can be pumped to the heat exchanger through a
thin poor conductor of heat that is well insulated..
[Edited on 29-5-2018 by coppercone]
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markx
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I worked with coupious amounts of chlorine during my days in the supercapacitor/carbide derived carbon related field at the beginning of the 2000s. We
had a rather sizeable stockpile of pressurized high purity chlorine in standard 50L sized cylinders that held about 60kg of the liquified gas in a
fully charged state if I remember correctly (guess there was some headspace left in the cylinder). Sometimes we had five of those cylinders in house
and two flowing concurrently. The cylinders were made of common (or perhaps less common) carbon steel, but no fancy stainless alloys. The valves on
the cylinders were made from a brass alloy. They were chrome plated on the outside, but inside was bare brass.
Well long story short.....absolutely everything corroded in contact with chlorine and moisture from the air. As long as the chlorine is anhydrous,
there is little chance of major corrosion taking place and even common alloys can withstand the effects, but wet chlorine is a totally different
animal. None of the components that came after the actual chlorine cylinder and became exposed to moisture at some point, held for long and were
subject to constant failures due to corrosion. The alloy composition was quite irrelevant....high grade stainless steel and special alloys corroded at
a visually observable rate and none of the fancy "chlorine rated" components from "Swagelok" justified their astronomic cost. In fact we used regular
copper tubing and standard brass pipe fittings and ball valves for years in the low pressure chlorine supply systems for feeding the reactors. To be
honest these held up better than the specialty grade components and cost basically nothing in comparison. Also the high end chlorine pressure
regulators at the cylinders were subject to failure as the membranes corroded and started leaking quite often. There is no escape from corrosion
damage when dealing with chlorine gas that is not completely anhydrous and the only way to get some service life out of the operation is to engineer
the system from massive and robust components. For membrane regulators and thinwalled parts the only thing that worked was pure PTFE or fully PTFE
lined components.
It was a nightmare to maintain the systems....everything, invariant of alloys used, became coated in hygroscopic deposits of chlorides and was
constantly wet, slimy and rusting away under your very eyes. A situation I would not want to encounter on my personal work premises....
As for the lethality of chlorine....well it is not a very effective poison...I survived the nice "atmosphere" for years  Not to say that suddenly stepping into a room full of the good stuff will not knock
you on your ass (don't ask how I know), but for sure you will not keel over dead at the very first breath.
All in all a nasty subctance to work with, especially if you are not prepared to sacrifice all of your tools and equipment as subjects for feeding the
abhorrent corrosion that surrounds this element inherently.
Exact science is a figment of imagination.......
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WGTR
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Rather than storing chlorine in liquid or gas form, perhaps storing it on silica gel would work for you as a practical and safer compromise. Adsorb
it at low temperatures, desorb it by passing a heated gas through the silica bed.
Note the short section about chlorine storage. It pertains to stripping chlorine of low partial pressure from air.
Attachment: US3063218.pdf (456kB)
This file has been downloaded 211 times
Partial pressures closer to 1atm will get you much better results:
https://pubs.acs.org/doi/pdf/10.1021/j150415a004
(sorry, link only)
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coppercone
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Interesting storage method, like storing hydrogen in palladium or whatever.
Markx, are you sure there was not some kind of process defect from swagelok? I honestly expect nothing but the best from them.
Did you bake the fittings prior to use age? I believe they come lightly greased sometimes. Maybe they were using old grease or something?
And did you have any kind of problems with moisture getting back into the regulators/valves after they were used? (my idea was to basically heat the
fittings after use, pull a vacuum on them, then quickly cap them off.
On another note, is there some kind of nonreactive moisture scavanger that can be used inside of the tanks? Like if you put molecular sieves in em.
(2A ? need to look at molecule size)
And by low pressure I assume you mean the vaporization pressure of chlorine (~100psi)?
[Edited on 29-5-2018 by coppercone]
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markx
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| Quote: Originally posted by coppercone | Interesting storage method, like storing hydrogen in palladium or whatever.
Markx, are you sure there was not some kind of process defect from swagelok? I honestly expect nothing but the best from them.
Did you bake the fittings prior to use age? I believe they come lightly greased sometimes. Maybe they were using old grease or something?
And did you have any kind of problems with moisture getting back into the regulators/valves after they were used? (my idea was to basically heat the
fittings after use, pull a vacuum on them, then quickly cap them off.
On another note, is there some kind of nonreactive moisture scavanger that can be used inside of the tanks? Like if you put molecular sieves in em.
(2A ? need to look at molecule size)
And by low pressure I assume you mean the vaporization pressure of chlorine (~100psi)?
[Edited on 29-5-2018 by coppercone] |
Don't misunderstand my intentions...I have no plans to claim that Swagelok fittings suffer from any kind of quality defect regarding workmanship or
material choice. They make high end components that are really excellent. My point was just that in such an agressive production environment that we
had, absolutely everything corrodes and fails irrelevant of material and quality. Throwing expensive fittings to the slaughter at the mercy of the
corrosion made no sense.
The scrubbing systems can be applied on the lines, but moisture gets in anyway (unless you work in a space suit under inert and totally dry
atmosphere). Changing the cylinders and performing maintenance work will allow moisture to creep in momentarily and that is enough. Unless you
dissassemble the whole system, clean it out with water and bake it dry afterwards...then assemble anew. Would make sense in small scale lab setup, but
on an industrial setting it is unthinkable practice. And oh yes...the scrubber systems will also corrode and fail (I know from practice  )
Exact science is a figment of imagination.......
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coppercone
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ok but what do you expect from this procedure.
After use a vacuum is hooked up to the closed valve. Vacuum and heat are applied. The swagelok cap is heated in the oven to 150c.
The vacuum is broken and the hot cap is quickly tightened over the valve. The cap has a silica gel packet glued in it.
Do you think this will protect the valve?
Or are you saying air diffuses into the blasted thing as its operating? I figured it would be connected to any glassware through some kind of trap.
Perhaps after being connected to the glassware aetup a vacuum can be pulled and heat applied to the closed valve to discourage backflow of any
humidity.
Then turn on argon purge and add the reactants to the reactors , seal the system against moisture with cacl2 trap, disable purge gas, then start
chlorine flow.
Its a bit of procedure to go through but it should work? Or still some kind of problem exists?
The next level of complication that i can phatom would be to add a copper tube on a t junction by the valve exit, cap the thing, and pull a vacuum on
the tube then heat it and seal the thing with silver solder each time after use.
I think it will work unless you get water going backwords through the fucking chlorine gas as backflow even with the baking and calcium chloride.
I say to cap it after every use because i figure the valve might leak a tiny tiny bit, enough for corrosion to start.
[Edited on 30-5-2018 by coppercone]
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aga
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Do i recall correctly that len1 came up with some storage method for chlorine involving salt water ?
Suppose i'd better read his paper again (it's in the library).
Edit:
Perhaps i'm missing the point and there's some reaction an Amateur would really want to do at about -40C with large volumes of liquid chlorine ?
[Edited on 30-5-2018 by aga]
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Panache
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Sharp makes an ultralow with vacuum plates as insulation, once at temp they sit idle for most of the time. There isn a power failure backup that is
essentially a upside-down log cylinder that vents the atmosphere that i think is right for quite a long time, it uses the normal evaporator not he
ultralow.
the second stage on ultra lows always use ethane as the refrigerant.
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