Grade of Helium

[arthurng311]

Hi, I am looking to get a 18/45 fill in Hong Kong for a tech 1 exploration dive. However no diveshops stock helium in Hong Kong, i am posting here to ask what purity of helium do i need for scuba fills? Anything i should look out for? Thank you all in advance!

 

[michael-fisch]

The cheapest most impure helium I've ever found was 4.6 grade.
4.6 grade is 0.99996 pure or a total impurities of 40ppm.
The usual cheapest grade I can get is 5.0 or 0.99999 pure or a total impurities of 10ppm.
The cheapest Helium grade is several orders of magnitude better than you need.
Medical O2 is rated 2.5 or 0.995 pure with 5000 ppm impurities and no one gripes about it.

Michael

 

[Wookie]

The cheapest most impure helium I've ever found was 4.6 grade.
4.6 grade is 0.99996 pure or a total impurities of 40ppm.
The usual cheapest grade I can get is 5.0 or 0.99999 pure or a total impurities of 10ppm.
The cheapest Helium grade is several orders of magnitude better than you need.
Medical O2 is rated 2.5 or 0.995 pure with 5000 ppm impurities and no one gripes about it.

Michael

No one is breathing medical grade at 6 or 10 atmospheres, either.

The lousiest grade I would sell is 5.0

I know tech divers that use balloon grade.

I wouldn't use balloon grade myself, I would use 5.0 myself.

 

[abnfrog]

the only balloon grade we see here has sulfer added (to stop kids from breathing it ) and I wont mix that ...I still have a t with med grade from last year but it getting harder to get with less than 30 days notice

 

[rjack321]

5.0 or 0.99999% pure also known as "Five-nines" in English. I have no idea how helium is graded in the far east however.

 

[nadwidny]

The last 2 T's I had were balloon grade ( I have no idea how many 9's that is). Because I had a lab that could analyse the gas I did and it was fine, so I used it.

 

[Chris H]

You guys have your decimal in the wrong spot. 5.0 is 99.999%. Whatever you are getting, you need to understand what impurities are in it. I worked in a lab for a 5 years, and sometimes the impurities were Oxygen and Nitrogen. Obviously not a big deal. If you don't have a lab, I guess I'd use 5.0. If you know your supplier, you may find out they pump all of their helium from the same tube trailer, and the 5.0 is purged a few more times.

 

[broncobowsher]

The impurities are what I worry more about than the purity itself. 99.0% He and 1% air, great. 99.0% He and 1% CO, balloon time. But I don't have a lab.

 

[Miyaru]

I'm using 4.6

....until my last buffer will be empty. Last month my supplier told me they now only deliver to hospitals with an MRI scan. "Call back in 10 weeks". Price went up 150% compared to 1 year ago.

 

[rjack321]

The last 2 T's I had were balloon grade ( I have no idea how many 9's that is). Because I had a lab that could analyse the gas I did and it was fine, so I used it.

there's no such thing at my supplier

there's also no helium right now either