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Nitrogen purging

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#1 sonny.barile

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Posted 21 February 2020 - 07:08 PM

What does nitrogen purging do for binocular telescopes like the Oberwerk and APM 100’s? 

 

 

 

 



#2 hallelujah

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Posted 21 February 2020 - 07:18 PM

Keeps them internally fogproof.

Over the years, helps to prevent internal fungi.

 

https://opticbird.co...gen-binoculars/

 

Stan


Edited by hallelujah, 21 February 2020 - 07:22 PM.

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#3 Yarddog

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Posted 21 February 2020 - 07:31 PM

Zeiss used to say that purging was not necessary since theirs were leak proof. Somewhere along they changed their mind.


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#4 Russell Smith

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Posted 21 February 2020 - 08:19 PM

Everything will leak in time.
Who really thinks a vacuum can last?
Unless you live in deep space.
Wonderful while things stay intact.
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#5 sonny.barile

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Posted 21 February 2020 - 08:40 PM

Keeps them internally fogproof.

Over the years, helps to prevent internal fungi.

 

https://opticbird.co...gen-binoculars/

 

Stan

 

Thanks this was helpful. 

 

Im lulling over some 100mm offerings. Some are nitrogen purged some are not. I live in the North East So moisture is a killer. I should probably get a nitrogen purged model. 


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#6 chubster4

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Posted 21 February 2020 - 08:42 PM

It's also an inert gas...will minimize oxidizing reactions that might degrade coatings.  


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#7 markb

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Posted 21 February 2020 - 09:30 PM

Nitrogen is not inert, Argon essentially is. Both are sold as a dry compressed gas.

 

Argons is pretty cheap and is very commonly available as a welding shielding gas. It is present in the atmosphere in far larger percentages than most realize, far more than CO2, at just under 1%.

 

That said, Nitrogen is far less reactive than oxygen at normal temperatures and environments, and the elimination of the oxygen as well as the water content of air should prevent mold and other growths and prevent coating degradation.


Edited by markb, 21 February 2020 - 09:31 PM.

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#8 GamesForOne

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Posted 22 February 2020 - 08:22 AM

If the binocular does not hold positive pressure, then the purging is only short-term -- and I doubt any binocular out there holds positive pressure for more than a year at best. Stan's article reference above says "decades". Show me the data because I don't believe it.

 

The better it is sealed the longer it will last in a damp environment before water vapor makes it way inside. But I really doubt the internal purge gas is retained for very long.

 

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#9 Pinac

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Posted 22 February 2020 - 08:48 AM

If the binocular does not hold positive pressure, then the purging is only short-term -- and I doubt any binocular out there holds positive pressure for more than a year at best. Stan's article reference above says "decades". Show me the data because I don't believe it.

 

The better it is sealed the longer it will last in a damp environment before water vapor makes it way inside. But I really doubt the internal purge gas is retained for very long.

 

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Fully agree, based on my own experience.

Pinac


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#10 hallelujah

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Posted 22 February 2020 - 09:14 AM

https://www.cloudyni...led-binoculars/

 

Stan


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#11 Peterson Engineering

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Posted 22 February 2020 - 09:15 AM

What an interesting topic.  I've been thinking about developing kits for recharging binoculars and also working on a way to permit sealing of SCTs for inert gas as well.  Based upon years of stepping out of a warm house into a frigid night, if the binocular doesn't contain an inert gas it's not truly suitable for astronomy.

 

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#12 garret

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Posted 22 February 2020 - 09:55 AM

 

Im lulling over some 100mm offerings. Some are nitrogen purged some are not.

The ones filled with gas must have somewhere a filling valve


Edited by garret, 22 February 2020 - 09:55 AM.

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#13 Andeas72202

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Posted 22 February 2020 - 11:06 AM

The ones filled with gas must have somewhere a filling valve

I assume, that nitrogen purging is done in some kind of a glove box: put the disassembled binoc in it, suck the air out of the chamber, flush with nitrogen gas and assemble the binoc inside the glove box. One open interface (e.g. unscrewed objective lens) per side would be sufficient for this procedure. Thus no valve required.


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#14 sonny.barile

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Posted 22 February 2020 - 11:17 AM

Thanks for all the replies. This is educational for my purchase. 

 

The models I am considering are 100 mm APO types like the Oberwerk and APM. Are these brands of sufficient quality to be considered sealed well? 

 

I would assume that having it is better than not if living in a high humidity location.....yes?

 

I am located in northern NJ.

 

 


Edited by sonny.barile, 22 February 2020 - 11:19 AM.


#15 sg6

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Posted 22 February 2020 - 11:23 AM

Cannot see it doing much past the initial phase.

The atmosphere is 78% nitrogen, so a nitrogen purge is not a great deal. The main aspect is they remove any water so it is dry nitrogen inside.

 

As I cannot see how any binocular we use will be hermetically sealed, then as the binoculars warm up and cool down the everyday atmosphere were walk around in and breathe will enter the binoculars, and bring with it water vapor. For complete sealment it likely means no focus adjustment poiible also. Agreed small amounts of gas exchange but binoculars are not going to be sealed.


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#16 Binojunky

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Posted 22 February 2020 - 12:49 PM

I believe that Argon has bigger molecules than Nitrogen and is less prone to leakage, or so the manufacturers who use it say?,D.


Edited by Binojunky, 22 February 2020 - 12:50 PM.

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#17 Pinac

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Posted 22 February 2020 - 03:56 PM

Correct, but the leaking out of Nitrogen or Argon seems actually less of a problem than the leaking in of oxygen (which is a small molecule).

The sheer absence of Nitrogen or Argon in the glass would have no negative consequences by itself. But what usually happens is that oxygen leaks into the glass (it will also do that if Nitrogen or Argon haven’t fully „left“ yet) due to partial pressure differences.

That‘s at least my understanding.

 

Pinac


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#18 GamesForOne

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Posted 22 February 2020 - 05:58 PM

I believe that Argon has bigger molecules than Nitrogen and is less prone to leakage, or so the manufacturers who use it say?,D.

That article Stan referenced above also states that since nitrogen is diatomic it has a bigger total molecule size than inert argon, so it is really no difference. Don't be sold.

 

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#19 hallelujah

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Posted 22 February 2020 - 06:26 PM

I believe that Argon has bigger molecules than Nitrogen and is less prone to leakage, or so the manufacturers who use it say?,D.

Dave,

 

Once upon a time Minox used Argon Gas because it was supposed to be a "superior" gas filler.

Today Minox uses both Argon & Nitrogen.

Argon is used in their top-of-the-line binoculars. wink.gif

 

Stan


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#20 Mark9473

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Posted 22 February 2020 - 06:37 PM

The only thing that Argon is superior for is that, because it's a heavier gas than Nitrogen, it is more efficient at flushing out the existing air in the instrument if there are irregular shapes.

And probably it sounds fancier in marketing literature.

After that, it's all physics and Pinac got it right - it doesn't matter if the gas inside migrates out (and it's the partial pressure difference between inside and outside that drives this, so nitrogen is vastly more favourable than argon), it's whether the seals are good enough to keep water vapour and oxygen out.



#21 faackanders2

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Posted 24 February 2020 - 10:10 PM

Everything will leak in time.
Who really thinks a vacuum can last?
Unless you live in deep space.
Wonderful while things stay intact.

That is like saying why get water resistent or waterproof watch.  It does make it last longer even though eventually the seal will break or wear out.



#22 faackanders2

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Posted 24 February 2020 - 10:11 PM

The only thing that Argon is superior for is that, because it's a heavier gas than Nitrogen, it is more efficient at flushing out the existing air in the instrument if there are irregular shapes.

And probably it sounds fancier in marketing literature.

After that, it's all physics and Pinac got it right - it doesn't matter if the gas inside migrates out (and it's the partial pressure difference between inside and outside that drives this, so nitrogen is vastly more favourable than argon), it's whether the seals are good enough to keep water vapour and oxygen out.

Argon may be larger/heavier/inert less likely to leak or react.



#23 faackanders2

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Posted 24 February 2020 - 10:17 PM

If the binocular does not hold positive pressure, then the purging is only short-term -- and I doubt any binocular out there holds positive pressure for more than a year at best. Stan's article reference above says "decades". Show me the data because I don't believe it.

 

The better it is sealed the longer it will last in a damp environment before water vapor makes it way inside. But I really doubt the internal purge gas is retained for very long.

 

---

Michael Mc

My 25x100 apogee binoculars got water dew inside and it took about a moth inside a sealed container with flower drying decadent to dry them out so they were useful again.


Edited by faackanders2, 24 February 2020 - 10:17 PM.


#24 Cory Suddarth

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Posted 28 February 2020 - 09:24 PM

I assume, that nitrogen purging is done in some kind of a glove box: put the disassembled binoc in it, suck the air out of the chamber, flush with nitrogen gas and assemble the binoc inside the glove box. One open interface (e.g. unscrewed objective lens) per side would be sufficient for this procedure. Thus no valve required.

Andeas72202, You are close, on the Fujinon Polaris series, on the lower body by the hinge, there is a screw on the left and right side. It is for gassing each chamber. Screws are removed, glass is set in a bell jar, ambient air sucked out, then only nitrogen (N2) is allowed to fill the bell jar, and thus the glass interior.  Make sure the "o"-rings didn't run away, put screws back in place.

 

Cory



#25 garret

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Posted 29 February 2020 - 02:12 AM

Is the gas inside under pressure?




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