Argon vs Nitrogen

Argon, Neon, Krypton and Xenon are called noble gases for whatever the reason (Inertness, reactivity and for other uses). If Nitrogen is working for you then why use Argon? (Look for purity of N2 ---and cost). It all depends on Storage Temperature, Sealing, Storage Container itself, and Purity. As an Example: Polyethylene beakers are as good as PTFE (Poly-Tetra-Fluoro-Ethylene AKA Teflon) for chemical resistance and it will do the job but people see a lot of glory in Teflon (PTFE - of course for temperature)

We are strict at keeping minimum levels of contamination getting to the product we manufacture, this is the reason we want to purge / air vent with argon. It is also used in other areas of our manufacture so is readily available.

I have also heard that argon being heavier than air is another reason it is preffered to nitrogen when purging, am interested in other peoples views on this? if anyone has first hand experience when comparing the two.

We are moving towards teflon for other consumables, but beakers we have changed to Pyrex glass. As you can see contamination is high priority on our development list.

Argon is only superior depending on the process. if it is an actual welding process, nitrogen can be picked up by the molten steel and act as an Austenitizing element, which is why Argon is used for welding instead of Nitrogen. Argon is used in double pane windows because it's thermal conductivity is much lower than nitrogen as well.

but for virtually all other processes Nitrogen is superior due to it's much lower cost. if this is simply a storage cabinet for consumables, I would definitely stick to Nitrogen. Argon would only be superior as a shielding gas for welding operations.

Two of the feed applications will be for welding. A number of components being welded will be within the storage cabinets also. We also store electrodes which once assembled go into a lamp.

I was just looking for some science behind the change as it was recommended by experts in our manufacturing field due to its inert properties/heavier weight.

''nitrogen can be picked up by the molten steel and act as an Austenitizing element, which is why Argon is used for welding instead of Nitrogen.''

This is enough information as using argon will cut out the chance of this all together. Costs are not really a problem as we have more than enough argon being used on 3 large Furnaces within our manufacturing.

Actually nitrogen is a ferrite strengthener and embrittling agent. Argon is recommended as shielding gas as it does not embrittle ferrite in steel. Milo

Sorry Milo, you're right, it is a ferrite former. mea culpa. I remember that we had to mix a small amount of N2 into our shielding gas when doing (relatively) thick section welds on Duplexes to compensate for the nitrogen loss from the weld pool. but I was thinking for some reason the weld without nitrogen was shifting too much to the ferrite side, but you're right, it was the opposite.

Nitrogen is about 3% lighter than air. It diffuses rapidly with air and won't stay in an open top container. Nitrogen will not displace air. *** Argon is about 38% heavier than air. It diffuses more slowly in air than nitrogen does. It will stay in an open top container much longer than nitrogen. Argon will displace air.

Sorry, I overlooked the mention of welding. I had started out my response with the relative inertness of the two gasses. But, I thought that was getting a little too long winded. *** Nitrogen is far more chemically reactive than argon. *** Electric arcs cause nitrogen to react with oxygen forming nitric oxide and nitric acid. *** Hot metals can react with nitrogen forming nitrides and other compounds. *** Ferrites are formed when oxygen reacts with the hot metals. *** Any or all of these may fuse together forming complex materials, some of which may be the compounds being referred to in your replies. *** Argon has none if these characteristics. *** It is almost totally inert. *** *** *** The noble gasses do not form ties with the common elements, *** They hold themselves aloof from common chemical needs. *** With very few exceptions they will not deign to consort with common chemicals. *** They are truly the nobility of the chemical world. *** They are chemical snobs of the highest order.

Nice post. In the world of metallurgy and welding ferrite is "The solid solution of carbon in body-centered cubic iron, a constituent of carbon steels."

We agree that ferrite may also be defined as mixtures of ferric oxide with other oxides, but that is NOT the sense of ferrite in the comments of Rorschach and myself.

Loved the "chemical snobs of the highest order." Welcome to CR4. Milo

Lol nicely put, many thanks all the info and peoples replies are a great help.

IMA

with regards to your comment ** diffuses more slowly in air** if we was to have an open top container and fill it with argon how long are we looking at for the argon to mix back into the air?

A lot of that will depend on how much wind there is. assuming still air, I'd expect 5-10 minutes might be possible, but that is purely a guess on my part (one in which I didn't even bother to wipe it off after plucking it from my arse), but with airflow/wind, all bets are off.

ha it would be in still air, but i think the periods of time i am looking at might be a little ambitious.

thanks for your amusing help either way

The diffusion rate can be slowed by lowering the temp. *** The taller the container the more time it takes to diffuse. *** The faster the parts are removed or replaced, the faster the diffusion. *** Taking parts out, or putting them in, would best be done with tongs, of whatever type you prefer, to prevent the major disruption of a hand moving in and out of the argon. *** In any case, I would think that even in an open-topped, average height, room temp. container it would be rather rapid diffusion if it took only 15 minutes. *** CO2 @ R.T. in an open topped 10 gallon (U.S., not G.B.) aquarium lasts over 15 minutes in a classroom, where the air is never very still. *** This is used to demonstrate gas density difference with soap bubbles floating in mid air, when a short time before the invisible gas was poured into the aquarium, they fell to the bottom and broke. *** Now that I think about it this would make an interesting demonstration of diffusion. *** The addition of a slide on cover, or a pivoted cover that rests on the container's top, will increase your use time tremendously, but only if the cover slides slowly on or off. Two or 3 seconds is slow enough.