Recreational Helium?

[AndyNZ]

My feeling is helium is expensive, and getting harder to aquire both by cost and by gas suppliers recent policies. Helium is a tool that is very useful in deeper dives and aids in certain deco schedules but to just throw some HE in a tank so you can go a little deeper for a very short time seems a waste.

I'd agree with that. Until we get some decent nuclear fusion reactors (EFDA-JET, the world's largest nuclear fusion research experiment) up and running, there's a fixed amount of Helium in this world and every time it's breathed out, it's gone....

 

[Reg Braithwaite]

One agency has 2 levels of recreational trimix with a depth limitation of 160ft. It also allows minimal deco. Who are they trying to kid? It is an attempt by a tech agency to grab a few more levels of certification where if someone wanted to perform those types of profiles they should do it properly with double tanks, a high PO2 deco gas and proper preparation and training to spend more than a couple of minutes at those depths.

If we are thinking of the same agency, you can go straight through their tech training without either rec trimix course, and you can alos go straight to the second trimix without their first. In fact, I think it is really very simple: the first rec trimix is single tank, no deco. The second is doubles plus a deco bottle. A student can probably pick their course on that basis alone.

 

[wedivebc]

Here's the results of Meyer-Overton study for reference.... they argued (in 1908, I think!) that the narcotic effect of a gas was proportional to the solubility of the gas.

Correction, inert gas. Oxygen is metabolized so the effect is somewhat less.

 

[wedivebc]

The second is doubles plus a deco bottle. A student can probably pick their course on that basis alone.

I didn't see anything about double tanks but if true, what makes it a recreational course?

 

[AndyNZ]

I had heard helium was less narcotic, just curious about whether or not the effect is reduced, depending on how much narc comes from O2 versus N2.

My personal opinion.... there's no difference between N2 and O2. In the Meyer-Overton study, there "reasonably similar" enough for it to boil down to individual physiology.

So I don't think there's much perceiveable difference between a 21% and 40% nitrox mixture. But if you compared a 21/35 (O2/He) mix with air, there's a huge difference.

 

[texdiveguy]

I persl. find those diver's whom have gone through this 'other' agencies recreational trimix class that allows only NDL diving, have been sold a bag of goods!

 

[AndyNZ]

Correction, inert gas. Oxygen is metabolized so the effect is somewhat less.

Cool, that makes sense.... the higher solubility is offset by the fact that it's metabolised.

Thanks for the clarification.

 

[Reg Braithwaite]

I didn't see anything about double tanks but if true, what makes it a recreational course?

If they had a forum here I would ask them

I'm just trying to obtain a second opinion about the merits of taking a course on diving He within recreational limits, and hoped to get an opinion from TDI or its instructors as to whether there were good reasons not to do so.

They aren't the only agency offering something like this. The TLA agency also offers Recreational Triox, it's apparently almost identical to the first half of their Tech 1 program, but accessible diving singles.

 

[texdiveguy]

If they had a forum here I would ask them

I'm just trying to obtain a second opinion about the merits of taking a course on diving He within recreational limits, and hoped to get an opinion from TDI or its instructors as to whether there were good reasons not to do so.

They aren't the only agency offering something like this. The TLA agency also offers Recreational Triox, it's apparently almost identical to the first half of their Tech 1 program, but accessible diving singles.

I think from the comments so far from us that actually do mix diving, you can deduce that a recreational/NDL trimix course and certf. is pretty lame in the real world of trimix diving. Save the money and time and go about it in a more direct fashion were the training/certf. results have merit and usage. IMHO

 

[Reg Braithwaite]

I think from the comments so far from us that actually do mix diving, you can deduce that a recreational/NDL trimix course and certf. is pretty lame in the real world of trimix diving.

I hope you can appreciate that I might respect your experience and value your opinion without seeking your approval.