Helium question

[Rings890]

I am a TDI Advanced gas blender (# 201940) I am having some trouble getting UHP (Grade 5) Helium from my local suppliers. A question my rep asked was could I use Medical grade Helium, I didnÃÕ have an answer for him and I have been unable to find any documentation on this to give to him. So I am looking for some clarification on weather or not we can use Medical grade helium for Tri Mix blending or if it must be UHP Grade 5.


Thanks

 

[Rhone Man]

Can't speak for Helium, but in his excellent book, The Technical Diving Handbook, Gary Gentile expresses the view that using medical oxygen to blend Nitrox is a waste of money, and welder's oxygen is perfectly sufficient. I don't know what they teach on the TDI blending courses, but Gary still seems to be alive and well after blending his own nitrox for all those years.

Whether one agrees with that, or thinks that the argument can be extrapolated to helium, I couldn't say.

 

[ivobj]

As far as I understand, medical grade is always purer, so you can always use without any problem, but probably you will have to pay more for medical helium the same way usually medical oxygen is more expensive than industrial grades.

 

[DevonDiver]

I have a student that is responsible for non-destructive testing at a local ship-making plant. According to him, the industrial grade O2 used for welding at that plant has to be of a higher grade than medical O2 (issues with the strength and impurities in the welding process).

 

[Rings890]

Thanks for the info guys, the oxygen is not an issue. What I am worried about is the PPM of impurities that may be in a non UHP helium because of the depths that we are breathing this stuff at.

 

[DevonDiver]

Shouldn't your supplier/s be able to provide you with data on the ppm impurities in the gases they are sellling?

 

[nadwidny]

Thanks for the info guys, the oxygen is not an issue. What I am worried about is the PPM of impurities that may be in a non UHP helium because of the depths that we are breathing this stuff at.

Medical grade is more than fine to use. It is what I keep on stock at my place however at locations where I can't get medical grade I've used welding grade with no problems.

Who told you that you needed UHP for diving?

 

[Blue Abyss]

It all really comes out of the same bulk tube tankers. It is just a matter of additional testing and verification. The industrial grades are tested on a bulk batch basis compared to the med and scientific grades which are tested on an individual tank basis.
I talked to on of my gas suppliers and they have only one bulk source for all of their heilum grades it is all just a matter of paper work.