I work on vacuum systems, semi-conductor industry stuff.
Yeah the nitrogen will eventualy leak out. No such thing as a perfect seal. But a nitrogen atom is a bit bigger than say a helium atom, so it wont all leak out, mostly I would suspect it would leak to a point of neutral pressure with that of the surrounding air. 1 atmosphere I guess.
As an example: Helium balloons are made of mylar instead of rubber. Reason being helium atoms (molecules if you like) are so small they quickly leak out of the pores in the rubber. They also leak out of the pores in mylar, but not as fast. Thats why helium ballons only float for so long.
The O-rings in your oprics are likely viton. They wont make a perfect seal. Argon would make a better purge gas. Larger less reactive atoms/molecules I believe. Less reactive to chnages in temp ect aslo I think....
Bottom line. Nitrogen is much less reactive to heat ect.... than room air that has 20 some odd percent oxygen and other stuff. If the optics seal is good enough water molecules wont be able to get in. They are alot bigger than nitrogen molecules. And the leak rate will be so slow as to be not a concern.
No you cant open it and keep all the nitrogen. Gases occupy the space they are given.
so is argon/krypton even better than nitrogen? i hear the molecule is bigger
Last edited by SAKO75; 09/15/10.
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