Have you worked with hydrogen? Being less prone to leaving than He is an extremely low bar and very far away from the claim that it doesn’t ever diffuse through anything.
Diffusion works both ways, too. Oxygen outside of the membrane will also slowly diffuse into the hydrogen and helium mix, further complicating any attmpts to remain non-combustible.
No, but the post I replied to, and apparently you felt the urge to reply to my comment. But I now understand that you did not intend to contribute to the discussion, thanks for the clarification!
