OT - do-it-yourself nitrogen purging...?

[AJMD429]

Anyone ever re-purge a scope or other optic with nitrogen...?

I have an older EoTech that is an excellent holo-sight, but extremes of cold cause a hint of fogging, ever since some total idiot (...well, I'm not a total idiot, actually... ) took the thing apart. Getting it done at 'the factory' doesn't seem to be an option, since they haven't returned my calls or emails (and who knows where the actual 'factory' or 'service center' even is).

I know quick-release of compressed gas creates condensation issues, but I wondered why a person couldn't put such an optic in a container set up like a small sand-blast cabinet, open and ready to re-seal, then feed a slow stream of compressed nitrogen through the cabinet over the next 24 hours. Put a can of moisture-absorbing granules in with it, even.

For that matter, why not use Argon (since I do have a MIG welder)?

[pdentrem]

Open the unit to allow gas movement. Place in a cabinet with water absorber and use the gas with the largest atoms. Bigger the atom the harder it is to get pass the seals. Argon is bigger than Nitrogen. Nitrogen is used by industry as it is 5x cheaper than Argon.

Your welding gas is PURE Argon? Or a mix of CO2 and Argon? What is the H2O content? Is it listed on supplier's sheet?

Argon is heavier than air therefore you could use an open top box with a plastic sheet to keep the Argon in the box from leaving by the passing breeze etc. This will allow you to put the unit back together while still in the box, just do not have a breeze while you work in the box.

[ole pizen slinger]

Something to consider in choosing which gas to use. Argon is a noble gas and is not a diatomic molecule, while nitrogen is a diatomic gas and contains two nitrogen atoms to form a molecule. It may be that one nitrogen molecule is larger than an argon atom in which case nitrogen would be the better choice. Regardless of which gas you choose, it must be dry or it will fog when cold.
ole pizen slinger

[stretch]

I continue to be amazed a the depth and breadth of knowledge on this forum.

-Stretch

[damienph]

Something to consider... Argon is a noble gas and is not a diatomic molecule, while nitrogen is a diatomic gas and contains two nitrogen atoms to form a molecule.

Now I see where I went wrong; thanks for explaining that!!

[Tycer]

I've got an old Japan Tasco I purged by putting it in a half gallon Mason jar with a couple of oxygen absorbers(hand warmers) for a day. The O2 being absorbed left mostly nitrogen behind. It's done great so far (10 years) being used on days where it used to fog it does not anymore.

[retmech]

I've got an old Japan Tasco I purged by putting it in a half gallon Mason jar with a couple of oxygen absorbers(hand warmers) for a day. The O2 being absorbed left mostly nitrogen behind. It's done great so far (10 years) being used on days where it used to fog it does not anymore.

Now that is some clever thinking!

[pdentrem]

For real hi tech. Use a piece of pure Paladium as a Hydrogen getter. Without the Hydrogen there is no water.