Protective gases in practice

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AgX

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Relative Densities:

Air____ 1.29
Nitrogen1.25
Argon__1.78
Butane_2.71

With that small difference in density between Argon and Nitrogen resp. Air, is there a practical advantage yielded by Argon against Nitrogen concerning layer-forming in a volumetric cylinder etc. as protective gas during handling?
Or, to put it more simple: Is Argon heavy enough?
 

Jordan

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In academic chemistry labs that do a lot of air-sensitive reactions, argon is sometimes preferred for this very reason (higher density). Whether it actually makes a difference is another story. Many labs doing phenomenally air-sensitive chemistry (far more air-sensitive than anything used in photography) seem quite happy with nitrogen as an inert gas.

As PE notes, nitrogen is much cheaper than argon (consider that nitrogen is about 80 times more abundant in the atmosphere than argon).
 

markbarendt

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I doubt the density itself is an issue but I'd bet the relative specific gravity is. http://www.engineeringtoolbox.com/specific-gravities-gases-d_334.html

Nitrogen is lighter than Oxygen while Argon and Butane are heavier.

I work in the Natural Gas industry and Nitrogen is relatively cheap and used simply to move/flush the air out of vessels and pipes that are being repaired or tested, it's not there to protect the contents and it is the copious flow the cleans out the pipe.

In our case where we want a gas to form a protective inert layer the heavier gases would seem better suited to the task.
 
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AgX

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I checked prices over here and Argon is only 10% more expensive than Nitrogen.
 

Martin Aislabie

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I use Tetenal Protectan - which is roughly 2/3rd Butane & 1/3rd Propane.

Seems to work really well - the splashes and drips that cling to the side of half empty bottles of developer stay almost clear coloured for many many weeks

As both Butane & Propane gasses are colourless I find myself using the optical shimmer of non atmospheric gas to determine when the bottle has been sufficiently filled

While I am sure the inert gasses would offer a more comprehensive protection in critical cases, the Butane/Propane solution is sufficient in most photographic cases.

It also comes in a handy pre-packaged ready to use form thanks to Tetenal and one can seems to last a long time (several years for me)

I also use Protectan to pre-fill my small developer bottles with an inert atmosphere before decanting my large bottles of developer into them to avoid needlessly oxygenating the developer during the transfer process.

Martin
 

Jojje

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I have succesfully used Tetenal's Protectan in half-full (or half-empty) wine bottles... And vice versa: various "wine saver" gases have photographic use also!
 

Denis K

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Since gases mix over time, regardless of which gas you use the important determinant would be the quantity of inert gas you add relative to the remaining oxygen content. It would seem to me that other than the fact that propane/butane is easy to compress into a liquid inside a consumer type aerosol bottle, it would be advantageous only to the extent that injecting it in a bottle at the gas/liquid boundary could momentarily form a layer that would push the lighter air out of the top of the bottle. This would only work if you use a thin tube to inject the propane/butane at the liquid boundary and manage to do so without causing significant mixing flows within the bottle. Whatever boundary you introduce would dissipate over time, at which point the remaining air will mix with the inert gas. Tetenal Protectan comes with such a tube but how well it works is anyones guess. Tetenal claims you can witness the exclusion of air by hearing a change in the sound exiting the bottle. I never found this to be obvious enough to use as an indication and simply resorted to the method of injecting enough to cause 3 or 4 changes of atmosphere thereby statistically reducing the oxygen content. If I could find a cheap bottle of nitrogen gas I could do the same with much less fear of using flammable gases. Something tells me I'll never see another bottle of Protectan anyway, so next time I'll probably buy a can of something different.

Denis K
 

Ed Sukach

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Protectran is not available here... at least I havne not found it - anywhere - for years.

I use butane, dispensed accurately, from a Bernz-O-Matic "Mini Torch". Butane is readily available - from your (or my) local hardware store, or as the refilling cartridges for butane candles and cigarette lighters... and you don't have to buy a barrel full.
 
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