Should TDI Helitrox replace AN+DP?

[CAPTAIN SINBAD]

I am noticing that some TDI instructors are no longer teaching ANDP and are teaching Helitrox instead. While research into gas density and work of breathing isn't entirely new, it is causing a number of instructors to introduce Helium at depths that were previously suggested by DIR agencies (100')

"Helium appears to be the immediate solution for divers who are concerned about WOB and correlated medical issues (immersion pulmonary edema, CO2 retention, etc.) and for technical divers who are doing even normal dives to moderate depths. Seven times less dense than nitrogen, helium also ameliorates the severity of narcosis but brings with it a host of new obstacles, including extended decompression, cost and high-pressure neurological syndrome (HPNS) concerns."

Alert Diver | Performance Under Pressure

While availability of Helium and price of it (in many parts of the world) remains a factor, are we starting to see a general trend where technical diving courses will/should start with Helium at the entry level? Id also love to hear from technical diving instructors who hold the notion that diving to 150' orr 170' has "lessons for the technical diver" as has always been claimed by John Chatterton.

Thanks.

 

[decompression]

Yes......sadly though with the cost and availability of Helium the DP is still viable. For most people the clarity on mix at 150’ is extremely noticeable but it’s hard to put that into something meaningful until you’ve done dives on air and mix.

 

[rjack321]

really HPNS? DAN editors should know better

 

[JohnnyC]

I mean, it's not factually incorrect, but telling the local boy scout climbing a tree to watch out for altitude sickness sort of fits the same bill.....

For anyone not following, Helitrox doesn't get you any deeper, it just raises your END for the same 45m/150ft depth that AN/DP certifies you to. HPNS doesn't really start to develop on the shallow end until you're at least 3 times as deep.

 

[kelemvor]

Wasting helium by using it in open circuit diving should be banned along with the clowns wasting it in balloons.

 

[Marie13]

A number of friends who also dive the Great Lakes have suggested Helitrox/DP to take the edge off the narc you can get here with our cold/lower viz.

 

[tbone1004]

I was just quoted $1.91/cf with a 4-6month lead time by my gas supplier for 99.999% helium. This is on a commercial account where we buy lots of other gas and it was still that long of a lead time. When I bought the last lot around October of last year, it was a third of that price with a 4-6 week lead time. The lead time was not abnormal, but the price was a bit higher than it used to be. There is a 0% chance I'd dive OC helium at that price and if you're doing any sort of actual trimix diving, there is now a real ROI on rebreathers.

Helitrox is great and I think if you're diving in the 100-130ft range it's a real improvement in your diving, but at $2/cf it's just nuts

 

[rhwestfall]

and this is why I have not completed my [edit] Helitrox cert.....

 

[leadduck]

I mean, it's not factually incorrect, but telling the local boy scout climbing a tree to watch out for altitude sickness sort of fits the same bill.....

For anyone not following, Helitrox doesn't get you any deeper, it just raises your END for the same 45m/150ft depth that AN/DP certifies you to. HPNS doesn't really start to develop on the shallow end until you're at least 3 times as deep.

IIRC, IANTD Advanced Recreational Trimix certifies you to 51m / 170ft, whereas Advanced Nitrox is only to 42m / 140ft, isn't it? Anyway, the classes are almost the same. So it makes sense for the student to take ART instead of AN no matter what he's diving after class.

 

[Marie13]

and this is why I have not completed my cert.....

I’m not saying I’d do DP/Helitrox, just that it’s been recommended. A RB is not in my future (cost and mindset required). I’m most likely doing AN/DP next year.