alt Hacker NewsYou sure about that? Everything I've ever heard says that balloon gas is generally grade 4, which is 99.99% pure. Not good enough for MRI, but quite a lot better than 80%.
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Jblx2 • yesterday at 8:08 PM
>99.99% pure. Not good enough for MRI
What is the reason that MRI needs grade 6 vs grade 4 helium? I'm imagining that the superconducting wire is within a cryostat filled with liquid helium. Doesn't seem like there would be any appreciably partial pressure of things like nitrogen or oxygen at 4 Kelvin. I imagine the reactivity of oxygen is pretty low at 4 K as well. How much dissolved oxygen or nitrogen can liquid helium support? And how much solidifies out and sinks to the bottom of the cryostat?
Economically I expect it wouldn't be that pure, since it doesn't have to be that pure to provide lift, and party balloons are not trying to maximize lift.