How pure does Helium need to be to kill you?

[Popopo]

Sorry for repeatedly asking questions about this, but how pure does Helium need to be to kill? I keep reading about how balloon grade Helium is unreliable and mixed with oxygen, but at the same time I read that even balloon Helium is about 99.99 (4 digits) pure and it should say so if it isn't. On average worldwide "balloon gas" is still 95% Helium according to google. And only a few companies started mixing their Helium with oxygen, right? And those that do sell it as "balloon gas" rather than Helium. So am I just trying really hard to convince myself my Helium tank is sufficient to kill me or is it likely gonna do so? I seriously think that despite the warnings of others even balloon grade Helium will be sufficient and I'm just overthinking. That, or I am oversimplifying things for myself and the Helium is actually not pure enough. Wish it wasn't so difficult..

 

[Mare Imbrium]

As I said in another thread: I am also from Middle Europe. And there are many complaints from customers about balloon tanks with label 100% Helium, that balloons dont fly but lie on earth. You can imagine, that it contents no good Helium. Read comments on A......... de.

 

[Jblack]

Some companies may mix He with air. They would not use Oxygen that would be way too costly. In the US, balloon grade He is made by capture blow off He when filling high purity tanks. The blow off will have a fair amount of air but will not exceed 10%. That being said, if you run a shop and want to have the He cut further with air then that can be done as a custom fill. But if the air content is too high, then the balloon will not float in air. If someone labels an He tank 100%, I would be suspicious. The highest purity He available is 99.9995% and is a research grade generally used in super conducting magnets. Looking at what Mare Imbrium wrote, the part of the world where you are located may be cutting the He with a large amount of air. They don't do it prevent someone from CTB, but to increase profit on the sale of the tank.

 

[LaDagabba]

Here in my country pure (99,99%) Helium is avaible but it's 3 times as expensive as Argon, which has the same properties.