Grade 6 (6.0 helium = 99.9999% purity) The closest to 100% pure helium, 6.0 helium is used in the manufacturing of semiconductor chips – Grade 5.5 (5.5 helium = (99.9995% purity) Like 6.0 helium, 5.5 ultra pure helium gas is typically considered “research grade,” also used in chromatography and semiconductor processing
Grade 5 (5.0 helium = 99.999% purity) This high purity grade helium is also widely used for gas chromatography, mass spectrometry, and specific laboratory research when higher purity gases are not necessary, as well as for weather balloons and blimps.
Grade 4.8 (4.8 helium = 99.998% purity) The highest of the “industrial grade” heliums, 4.8 grade helium is often used by the military. The rest is classified...
Grade 4.7 (4.7 helium = 99.997% purity) A “Grade-A” industrial helium, 99.997% helium is mostly used in cryogenic applications and for pressurizing and purging
Grade 4.6 (4.6 helium = 99.996% purity) Grade 4.6 industrial helium is used for weather balloons, blimps, in leak detection
Grade 4.5 (4.5 helium = 99.995% purity) Often the grade most commonly referred to when people say “industrial grade,” 99.995% helium is most commonly used in the balloon industry
Grade 4 (4.0 helium and lower = 99.99% purity) Any helium that is 99.99% and down into the high 80 percents is within the range of purities referred to collectively as “balloon grade helium.”
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?
Turns out that you are right, some balloon gas is 80%. Specifically, the "Balloon Time" tanks you can buy at places like Target say "not less than 80%" helium.
On the other hand, I went to AirGas and a few other suppliers and they seemed to have 95%-97.0% helium gas as their definition for balloon grade.
Definitely worth knowing what you're getting, in any case, so you don't get ripped off, and so you can actually get that lawn chair contraption into the sky.
Moar hydrogen party balloons. Making partying fun again!
You have the entire collected knowledge of mankind at your fingertips. You could do 30 seconds of research and find an answer better than "I don't think that sounds right".
(The form in which Christopher Hitchens actually stated "Hitchens' Razor" is more symmetrical but unfortunately wrong: "What can be asserted without evidence can be dismissed without evidence". Anything can be asserted without evidence! It's only when something actually has been, in a given context, that dismissing it is -- in the same context -- a reasonable course of action.)
In this case it would be reasonable to inquire about the basis of the original remark, or to reject based on personal knowledge, or to reject based on a concrete citation. But an arbitrary non-technical vibes based rejection doesn't fit with how things generally work here.
So could you, right?