TIL, thx

This is very likely not true.

Would you like to offer a rebuttal more well reasoned and thought out than "nuh-uh"?

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".

> You could do 30 seconds of research

So could you, right?

What is asserted without evidence may be dismissed without evidence.

(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.)

While a reasonable principle I don't think it applies in context. People aren't expected to exhaustively source comments on HN. There's subjective etiquette to it.

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.

True but you can provide evidence to increase the quality of your claim.

You 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%.

>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.

Out of curiosity I did a minor amount of research to get an idea.

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.

Perhaps "balloon grade" here is not "party balloon grade". Weather balloons? Research balloons?

My guess is that places like AirGas aren't really supplying many weather or research balloons. I suspect the easier answer is 'Balloon Time is low grade crap aimed at people who don't know any better and just want to pick up some balloon gas while grocery shopping.' It's like the difference between people who go to a gas station to refill propane tanks, and people who swap them at Home Depot. (though the smart fellers do swap at Home Depot occasionally, if they need a fresher tank...)

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.

AirGas prioritizes industrial users, in the case of helium, copper welding. Argon is perfectly good enough for almost all welding purposes, but copper is different because of its heat conductivity. The heat from the weld really wants to go anywhere else. Helium has substantially higher heat conductivity than argon, which allows the heat to flow from the electric arc into the metal faster, resulting in better welds.

Obviously you can't have oxygen in welding gas; it would oxidize the shit out of everything.

A little bit of oxygen in party balloon gas is beneficial. Some kid will breathe it, and when they do, you didn't want them to asphyxiate themselves.

Do you know if the other 20% is oxygen (as was claimed) or if it's air? I just think the latter seems cheaper and more likely.

I think it may be CO2. CO2 in the gas would cause all sorts of unpleasant effects that would discourage continuing to breath it, and CO2 is probably cheaper to store and transport than oxygen.

https://www.bocgases.ie/files/balloon_grade_helium_factsheet... says 95% helium and 1% oxygen while https://dan.org/alert-diver/article/helium-gas-purity-what-i... says 97.5% helium but very unlikely for it to be as low as 80%

"An overview of the different common grades of helium" - https://zephyrsolutions.com/what-are-the-different-grades-of...

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.”

Interesting bit from that article wrt to transport infrastructure:

"most distributors simply stick to the industry standard transport of Grade 5. That is why for and [sic] end user of helium, a lower grade can cost more than the higher grades."

I wonder if one of you could be going by number of atoms, and the other could be going by weight?

Helium for diving is going to be a different mix than what's used for balloons. In diving it's used to reduce the partial pressure of oxygen, and also to quickly diffuse back out of tissues when returning to the surface. Very different application!

Sorry i was referencing "Balloon grade H is the least pure at 97.5 percent." from the diving article

source? the value I found is 97.5%+ helium for party balloons: https://www.grecogas.com/learn-our-industry/your-complete-gu...

People commit suicide with it because it's supposedly painless and quick.

Same applies to every gas that isn't carbon dioxide. Your body only cares about expelling CO2, it hasn't evolved a way to detect oxygen in the breathing gas mix. Divers know all about this.

I believe that that's the stuff you buy in the shop, the non-refillable containers. If you buy a proper refillable balloon gas cylinder it's the higher grade stuff. Source: bought the shop stuff, got disappointed, bought the cylinder, happy.

We're dumb enough now to have forgotten history.

Moar hydrogen party balloons. Making partying fun again!

I can personally attest that this is not foolproof, if it is even the case. Those helium tanks you can buy for large parties knocked me out as a kid. Lost consciousness fell to the ground, blacked out. Supervise your kids if you buy one!