BromicAcid
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Nitrogen cylinder, welding experience required?
I'd be surprised if this has not been covered elsewhere on the net, but here goes.
I've been contemplating purchasing a small nitrogen cylinder for running reactions under an 'inert' atmosphere. Or maybe argon, I
haven't yet decided. Problem is I have never welded, trying to get a little background I've surfed around a bit but it's really no
good. Prices online for new cylinders are beyond my safe budget so I want to be able to go into a welding supply store and say, "I want
....." and tell them what I'm looking for.
What I am looking for in layman's terms is a small cylinder not taller then .6 m or so, I would also need to know the fittings to go with it.
Who here has experience purchasing such a cylinder in person? I just need to know some jargon as I don't want them to know I am going to be
using it for chemistry not involving acetylene gas or whatever they use nitrogen with (I would also like to know specifically what they use nitrogen
with in welding) I am going to say that I am just starting so that I don't have to know everything but I should have some jargon to toss around
or something of the sort.
I'm sure for some people here this will be the easiest answer they have ever written, thank you in advance.
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blazter
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Don't know a whole lot about welding myself, but I do know that inert gasses are almost always used for MIG and TIG welding. If memory serves me
right the "IG" means inert gas. The inert atmosphere is needed to prevent the surface of the metal from oxidizing, and helps a cleaner weld
form. Typically, I think a mix of argon/CO2 is used for welding steel, N2 may be used for more specialty uses, like stainless steel or something like
aluminum.
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Mendeleev
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Why don't you try a paintball store or supplier. I don't know how much welding nitrogen tanks costs, but a paintball nitrogen tank can be
from $80 to $300. And range from 48 cubic inchess at 3000 psi to 88 cubic inches at 5000 psi. To refill just go to your local paintball field and
pay $5. This also depends on where you live. In countries other than the USA I don't think paintball is quite as widespread. The cheapest
paintball site I know is http://www.actionvillage.com/ In welding the inert gas is used to prevent oxidation of the weld giving a stronger more quality weld. Using an
inert gas ubrella allows you to avoid applying flux, something that decomposes upon heating to give inert gases. Direct inert gas is easier in that
you don't have to worry about pasting on any messy chemicals like zinc chloride and provides a constant shroud wherever you point the electrode
so long as your tank lasts so you don't have to reapply the flux or anything. I haven't heard of nitrogen being used in welding, why
don't you just get helium, the most inert of all elements and one commonly used for welding as well as filling baloons? Tell the guy it is for a
heliarc welder. It's basically an electric arc under a shroud of helium to prevent oxidation. It gives very good quality welds, but is a bit
slower.
Edit: My local Sam's Club sell small helium tanks for around $25 to fill baloons.
[Edited on 14-7-2004 by Mendeleev]
Trogdor was a man. A dragon man. Or maybe just a dragon. . .
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bobo451
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Just go to any welding supply and ask for a T-cylinder of nitrogen. The tank is about 5 feet tall (taller than you wanted), but refills are fairly
cheap. Cylinders can typically be bought or rented, but the purchase cost is about $80 for a new cylinder. Refills for a cylinder should be about
$15. Along with the tank you will need an inert gas regulator. Not sure on the price, but it shouldn’t be too much.
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Darkfire
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I have a tank of nitrogen which was gotten somehow with out going through the welding industry. Im not sure where it came from though.
\"I love being alive and will be the best man I possibly can. I will take love wherever I find it and offer it to everyone who will take it. I
will seek knowledge from those wiser and teach those who wish to learn from me.\" Duane Allman
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BromicAcid
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Yes, helium is readily available but it is too light, it would not efficiently flush a system. So it looks like nitrogen is not as widely used in the
welding industry as I had previously thought, although argon seems to be more available, but it looks like most of it is diluted with 25% CO2... hmmmm
not totally inert but decentish. Still thought I want my tank of nitrogen, I guess I'm just going to hit the welding places this weekend, or the
pawn shops and see what they have for myself. If nothing good, I could always take up scuba 
Thank you everyone for your imput till now!
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Mr Carrot
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Welding Gases
I am not a welder, but this is what I found:
You can get Nitrogen from welding suppliers - one reason it is not preferred is because it creates nitrogen oxides during welding. Nasty.
Welding grade Nitrogen is only 99.5% - you might have 0.5% Oxygen - if you are going to this much trouble, go for Argon.
You can get both pure and mixed Argon for welding.
Remember, you'll need a regulator to reduce your 200 atmospheres or whatever to manageable pressure. You'll need an additional fine control
valve and a bubbler to administer Argon into your apparatus.
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Johnny
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I -=AM=- a welder and you may purchace Argon strieght or w/ a mix of CO2 for MIG systems. - You can get this at most welding tank suppliers, the cost
is generally 40-80 DUS as a purchase. a regulator (manditory) will cost extra, simply ask them if they have a regulator to go with it. If they have a
used one they will sell it for a cheap price. (they often do). Nitrogen is a different story. It is not used as frequently as Argon. Argon can be
quite cheap! Just be relaxed and say you need inert Aron gor a MIG. You need the tank and a regulator. All the specifics are standardized. So they
won't be asking what type of threads or questions like that. Just say a standard set-up with Argon only.
If I was really bright I would have a cool sig.
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Nevermore
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Nitrogen is not friendly with welding since it creates very fragile nitrures during the time the mixture is over 900°C, if you need a PURE inert
atmosfere u can get PURE argon (remember to ask PURE since most of the time is mixed with 10% Co2 or 10% O2) or He(in welding is usually mixed with
20% Ar)...
Try checking also equipments for pubs, usually they use nitrogen to give the beer the creamy foam.
Nitrogen can be found too, but for applications different than welding..
Nevermore!
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mick
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nitrogen cylinder, welding experience
For reactions under dry/inert conditions argon is better than nitrogen because it is heavier than air, will fill a flask under gravity and is a lot
less reactive. In the UK the argon out of welding bottles is very dry, any water would ruin the weld. Because it is heavier than air the top can be
taken of a flask and stuff added quickly without lossing the argon, unlike helium. An easy way to carry out a reaction under dry/inert conditions is
to fill a balloon up with argon (I put three balloons inside each other and over inflate them first to reduce the pressure and when being used if one
bursts there is still two to go). The balloon can be connected to tubing with an elastic band. The equipment can be flame dried with argon blowing
through it and if heating the reaction, deflate the balloon first so no pressure builds up, as long as the balloon is part inflated no air/water can
enter the reaction and no serious pressure can build up. If the joints are well sealed and held together the worst that can happen is the balloon
bursts.
To keep stuff very dry they could be put in a container connected to an inflated argon balloon, as long as the balloon is inflated no air and water
can get in.
First posting for a while.
Hope its OK
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unionised
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I have seen a reference somewhere that points out that the permeabillity of baloon rubber to gases, and oxygen in particular, is rather high. The
author goes on to say that the baloons add a nice festive touch to the laboratory but that's about all. I haven't checked, but I would do
before I used this trick for anything critical.
From the point of view of an oxygen molecule in the air there is a fifth of an atmosphere of pressure forcing it into a ballon full of argon.
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mick
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nitrogen cylinder, welding experience required
Thanks
I think you have solved something that has been bothering me for ages. After using piped argon years ago, I started using balloons, but I always use
three balloons inside each other, my own technique. I could not work out why the outer balloon disintergated before the inner balloon which was
exposed to all the chemicals. I thought it was all the other rubbish in the air.When you think of partial pressures, osmosis and semi-permiable
membranes, I think you are right, the first balloon lets in oxygen rather than nitrogen, argon can not get out.
So the outer balloon is oxidised and falls to bits. Can you filter oxygen out of the air with a balloon?.
Someone used inflated disposable latex gloves, they were better than balloons.
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David Marx
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Was a good source finally determined?
I'm thinking of buying a lecture bottle of inert gas unless this thread finally resolved on a better idea.
alea iacta est
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BromicAcid
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My chemistry obsessions are subject to constant change, as such I never got to the point where I was going to purchase a nitrogen cylinder.
What I did find out though is that nitrogen for welding is not as widely carried for welding as I thought, it is mostly used for flushing lines when
it is used. Argon is considerably more available. The argon tank and regulator are available online and a small - medium argon tank can be picked up
for about $50 new and a regulator for less then $75. Any welding place will fill them for a reasonable price, ask for pure argon as has been said
before they sell mixes with CO2. The fittings are all industry regulated so there isn't a worry about buying the wrong adapters.
Comparing the price of a one time use lecture bottle (I've seen 1 Mol N2 lecture bottles sell for $45 on eBay) with the price of reusable argon
cylinders there is definitely an advantage.
However if you are truly looking for a good source of nitrogen and not just an inert gas in general you might have better luck getting a lecture
bottle of it.
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David Marx
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I was actually looking at buying argon aways, to check some inert organometallic work before posting it up here. I've done it in a university
lab but recently realized the some of them may be possible at home.
You are right though, lecture bottles are expensive. Especially since they cannot be re-used in any easy manner.
alea iacta est
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JohnWW
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The trouble with welding under a nitrogen atmosphere is that it forms brittle nitrides with the more electropositive metals at high temperatures,
especially Ti, Al, Mg. In particular, Mg can burn in N2. (There is some possibility that these may also react with CO2). This is in addition to
nitrogen oxides, where the arc extends to the boundary region between the pure N2 and the surrounding air. You should use argon, which cannot react
with any metal.
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vulture
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Are you sure about that? IIRC the formation enthalpy for magnesium nitride is quite positive.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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SuperNova
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Finally decided to register today 
Although Nitrogen is quite inert Magnesium does burn in pure N2 forming the nitride.
3Mg + N2 => Mg3N2
[Edited on 31-10-2004 by SuperNova]
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Esplosivo
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| Quote: |
Are you sure about that? IIRC the formation enthalpy for magnesium nitride is quite positive.
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This can be proven by the fact that burning magnesium, in a nitrogen enriched environment (i.e. by removing most of the O2 by passing air through
heated Cu) will give a substance which reacts with water giving a smell of ammonia. If one has an accute sense of smell the smell of ammonia can also
be smelt after adding some water to the result of combustion of Mg in normal air.
Theory guides, experiment decides.
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David Marx
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Argon Cylinder
Well I finally finished my comparision shopping and plunked down for a 20 ft3 argon cylinder with associated regulator. It took a bit of legwork to
find this particular size. Most sold online are larger and more cumbersome. I picked this one up at www.weldingdepot.com
Shipping was reasonable. I just got it today so I haven't had it filled yet. There are several places nearby that supply welders though, so I
shouldn't have any trouble.
Edited since picture was too large to upload! Alas...
[Edited on 6-11-2004 by David Marx]
[Edited on 6-11-2004 by David Marx]
alea iacta est
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basicelectromechanic
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Exactly right Bromic, although not very useful for welding nitrogen is useful as a " sweep" for copper lines during silver soldering, it
displaces air preventing the formation of oxide scale inside the tubing when it is heated with either air acetylene or oxyacetylene. Plumbers
don't generally use it but a good refrigeration man always does. After work is completed a system can also be pressurized to affirm hermetic
integrity.
Refillable bottles are available at refrigeration wholesalers, those guys can also supply a regulator and pressure hoses with 1/4 SAE fittings.
The gas isn't expensive but there is a deposit on the bottle.
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tom haggen
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Like your guy said bromic, nitrogen is used for flushing lines when brazing copper piping. They do this at my work all the time. They have nitrogen
there all the time. It really should not be that hard to get some nitrogen. Those tanks however, are expensive. Most buisnesses only lease them.
N/A
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chemchemical
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If you are looking to do a few inert reactions and don't need the amount in a tank, I would like to remind people that argon is used to preserve wine.
You can usually get a small "wine saver" bottle somewhere, you can then fill a balloon up with that and use it. I have not tried this yet but its the
way I will probably go when I need an inert atmosphere.
Also, I have access to argon tanks, is it possible to transfer the gas to another cylinder?
Edit: After searching this topic a little more, I think it depends on how often you will need inert conditions. You can buy full tanks, but then you
need a regulator, which can run upwards of 200$. I was able to find argon cartridges, similar to co2 or nitrous, these are cheaper and contain about a
balloons worth of argon and can be opened with "crackers".
The cartridges seem to be the cheapest and easiest solution for people running few inert reactions.
[Edited on 27-9-2009 by chemchemical]
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