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ES argon & nitrogen purged


Daniel-K

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No difference visually. I think Argon would escape more slowly than Nitrogen as Argon is more than twice as heavy. I think maybe that could be why they switched to Argon perhaps?

I thought they were heavier alright.

Barry

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I thought it was an "age" thing with the ES EP's.... The newer ones are AR purged the older ones are N2... Sure I read that somewhere but I could very easily have made that up..

You're correct, the older ones are Nitrogen and the newer ones are Argon. Its interesting to speculate why they changed ? :)

Edited by starfox
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I would imagine at the end of the day it comes down to which gas ES can get hold of at the right price. Both N2 and Ar are both inert gas and so moisture will not form inside of the eyepiece not that to be honest that I have ever came across moisture inside any of my none purged eyepieces.

My main preference for ES eyepieces is not what gas is inside but more that they have seals which prevent dust or other contaminates getting in when I'm giving the lens a blast with my rocket blower. By far the worst eyepieces I have had for letting dust between the elements were Hyperions. I swear I only had to show them my rocket blower and something would appear between a lens group.

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Would Nitrogen be more expensive than Argon when Nitrogen forms the main bulk of Earths atmosphere?

 

Comercial Nitrogen comes in various grades and I do not know which type is used in eyepieces but the Oxygen Free variety is expensive.

Alan

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I do like the fact you can hold them under running water to clean them :shocked: To me the real advantage the purging offers is a higher resistance to frosting up in the winter. All 3 of my purged eyepieces are more frost resistant, which is nice for me here. Either inert gas works great for purging- and as far as reactive, unpurged atmosphere (oxygen) filled EP's would most likely corrode things first. In reality this isn't an issue either IMHO

Edited by jetstream
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  • 4 weeks later...

Just a note:

In the pressure chambers where the eyepieces are assembled, it doesn't matter what gas is used.

However, under nitrogen the seals in the machine fail more often when nitrogen is used than when argon is used.

Since refitting the machine with new seals means down-time and lost production, argon, though more expensive than nitrogen,

results in increased production and lower per-unit cost than using the less expensive nitrogen.

Any claim this makes any difference to the end user is advertising hype.

ES has entirely changed over to Argon, though they still have stock of 20x100 in N2 version.

From the standpoint of amateur astronomers, it makes no difference which gas is used.

My own eyepieces are pressurized with a nitrogen-oxygen-argon mix to 14.7psi.  Always have been.

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I think the main reason to purge optics is to prevent internal fogging or the chance of anything growing in there, fungus? ( I've seen this in  old binoculars? )

Not only that, but if the optics are water tight, they are generally air tight so nothing can get inside. It probably wouldn't spoil the view, but will just annoy you if you knew there was something inside!

I know Nitrogen is an Inert gas which means it doesn't carry water or reacts with whatever it comes into contact with.  

Edited by Charic
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As an inert gas, argon doesn't bond with anything - except with a halogen like fluorine, and then under very controlled conditions. Nitrogen, on the other hand, bonds with many things. Such as hydrogen as NH3 - which is ammonia. But it doesn't bond easily so it's safe to use to replace air for applications that need the oxygen removed. Which one is cheaper? Well nitrogen makes up around 78% of the air we breathe. While argon is present at slightly under 1%. Go figure. But both are readily available and won't disappear.

Clear Skies & Chemically Inert,

Dave

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  • 6 years later...

I realise I am raising an old and well discussed thread. But found the content very interesting.
Maybe my post bringing the thread to the top will provoke renewed interest?

I was actually looking to see if nitrogen or argon offered any optical advantage over air.
Prompted by seeing Explore Scientific eyepieces with N2 or Ar stickers that didn't seem age related.
The ES site proudly proclaims argon. FLO are apparently selling new eyepieces with nitrogen. Go figure!

The consensus seems here to be that as long as you put a dry and reasonably non-reactive gas in there it doesn't matter.

Perhaps there is more argon available (lower price?) now we are no longer filling light bulbs?

Thank you to all who contributed to the earlier posts.

Hoping you all have non-fogged eyepieces whether N2 or Ar purged, or plain moist air.

David.

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It makes no difference in the eyepiece.  In fact, N2 leaks slower than Ar.

The reason Ar is used is related to down time in the factory.  The seals in the machinery in which the eyepieces are purged and get final assembly

tend to react under pressure with N2.  This means every few months the machines have to be shut down and seals changed.

That costs the factory in terms of maintenance and also lost production during down time.

Ar costs more, but saves the company a lot of money because it is not reactive with the seals in the machinery.

Hence, less downtime, lower maintenance costs and higher production.

 

Technically, air and N2 have virtually identical transparencies and indices of refraction.  Ar is a little different.  Ar is only 1% of the Earth's air, while N2 is 78%.

Due to the low density of gas in the eyepiece and the length of the eyepieces, it will make zero optical difference.

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18 hours ago, Carbon Brush said:

Hoping you all have non-fogged eyepieces whether N2 or Ar purged, or plain moist air.

 

17 hours ago, Don Pensack said:

The seals in the machinery in which the eyepieces are purged and get final assembly

tend to react under pressure with N2. 

All I can say is that ES eyepieces are tough. A few years ago I was observing in -30c and had frost and light ice form on my eyepieces, including the ES 18mm 82. I figure I'd test this purging and sealing of ES out...so..

I came in, filled the sink with the cold water tap and threw the 18mm in the water to "warm" it up :grin: a few minutes later I removed it, wiped it off, including the glass and no ill effects! No fog inside, no leaks and it was put back in service that night once completely dry.

Yeah, their tough and it makes zero difference what its purged with, argon or nitrogen IMHO.

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