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A comment on Unimpeded Permeation of Water Through Helium-Leak–Tight Graphene-Based Membranes. Parent comment

Re:Unimpeded Permeation of Water Through Helium-Leak–Tight G... by mensetmanusman on Wednesday February 15, 2023 @08:27PM (#34813711)
The kinetic diameter of water is smaller than helium because its polar nature allows it to adsorb and diffuse across solid surfaces.

This behavior helps it fit through small holes better than helium can.

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Re:Unimpeded Permeation of Water Through Helium-Leak–Tight G... by jhoechtl on Wednesday February 15, 2023 @09:09PM (#34814055)
That sounds counterintuitive. I have a leak-free water supply yet bet it wouldn't be Helium thight.
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Re:Unimpeded Permeation of Water Through Helium-Leak–Tight G... by tbrownaw on Thursday February 16, 2023 @12:21AM (#34815369)
There's a fun experiment where you can grease a kitchen strainer and if the holes are small enough it'll hold water because of the surface tension.
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Re:Unimpeded Permeation of Water Through Helium-Leak–Tight G... by twawaaay on Thursday February 16, 2023 @08:53AM (#34818578)
And at the same time it will pass a thick oil... all due to surface tension, polarity, etc.

Which is to say don't think about the filter as a geometrical sieve that has holes that pass molecules solely based on their size (either it fits or not).

This is not true even at macro level.

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Re:Unimpeded Permeation of Water Through Helium-Leak–Tight G... by whatshisface on Thursday February 16, 2023 @01:22AM (#34815709)
Your plumbing is leak-tight, but it's not water vapor-tight.
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Re:Unimpeded Permeation of Water Through Helium-Leak–Tight G... by fsckboy on Thursday February 16, 2023 @03:07AM (#34816215)
plumbing is not water vapor tight?
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Re:Unimpeded Permeation of Water Through Helium-Leak–Tight G... by blatant303 on Thursday February 16, 2023 @10:22AM (#34819830)
Plumbing for gaz and water follow different norms and pursue different sealing strategy. This distinction is omnipresent in gasket and screw thread engineering.
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Re:Unimpeded Permeation of Water Through Helium-Leak–Tight G... by hgomersall on Thursday February 16, 2023 @02:38AM (#34816065)
At the molecular level, nobody cares about your intuition.
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Re:Unimpeded Permeation of Water Through Helium-Leak–Tight G... by julienfr112 on Thursday February 16, 2023 @04:39AM (#34816764)
so true
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Re:Unimpeded Permeation of Water Through Helium-Leak–Tight G... by rkagerer on Wednesday February 15, 2023 @09:41PM (#34814297)
What is kinetic diameter?
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Re:Unimpeded Permeation of Water Through Helium-Leak–Tight G... by mensetmanusman on Wednesday February 15, 2023 @09:51PM (#34814368)
https://pubs.acs.org/doi/10.1021/jp412588f

Has to do with how to define the diameter of a molecule/atom when you consider how it interacts with other matter.

Atoms are fuzzy since they are mostly electrons moving about, thus there are a few different ways to define diameter depending on how this cloud behaves.

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