My AN/DP/Helitrox course

[rddvet]

I'd be surprised if anyone was actually taught it was OK to just identify by colour. However, I would agree that some people lax into dreaded old complacency.

Certainly all the tech agency curriculums, training manuals and instructor guides I've read are very explicit about the correct procedure for gas switches, including a deliberate tracing from 2nd to 1st stage and cylinder.

Like many things, people get away with it... untill they don't!

i know of many people that have been taught identifying via color or some other identifying feature is ok without tracing the hose. Its pretty scary.

 

[lowviz]

What are these dives that make you think you need 100% but are not deco dives?

Long ago my son and I were on an 80' /24m ocean dive and one of the divers, a DM, was practicing gear doff and don at the END of his dive. He lost his grip and corked up the downline. The captain immediately got him back down with another diver. He then searched everyone's gear for a cylinder of oxygen. PM me and I'll tell (only you) who the cap was. For me, lesson learned, there is much good that one can do with oxygen on the surface and almost no harm.

Some suggest that I should have just taken 'Oxygen Provider'. For the same money, I get to dive any O2 concentration. No brainer.

As for diving a pony and O2, I was considering going full tech. I wanted to get the feel of it in benign solo conditions. Not for me. I find my peace at recreational depths. O2 always comes with me but it rarely dives anymore.

with the appropriate gas switch procedure of identifying the bottle by markings and tracing the reg hose back to the bottle there is no reason to distinctly mark the reg. In fact.many good instructors teach not to use a reg distinction because it leads to the complacency of not actual tracing the reg back to the bottle.

Understood.

This is also why I suggested to stay off the 'slippery slope' of staged decompression for someone who only wanted AN. These skills are highly reinforced in DP but not in AN.

 

[RayfromTX]

I agree thats very stupid. I have no issue with colored regs even for 50%. My 100% regs have a green faceplate and hose. My only issue is people who are trained to rely on the color to identify the reg. Its dangerous. But if you are using the color to initially locate the reg but are then still tracing it back to the bottle I have no issues. The problem is alot of people are taught identifying color is good enough.

I use color coding for out of the water. My valves and gear is blue, my wife's are red, deco gas is green. It makes it easy to identify from afar or on the boat which is which. Identification in the water has nothing to do with color. That is all about labeling and physical tracing. I'm not looking for a green reg underwater. I know where the 50% is and I check the label and my wife checks the label.

 

[Graeme Fraser]

i know of many people that have been taught identifying via color or some other identifying feature is ok without tracing the hose. Its pretty scary.

That is scary. One of the critical aspects of teaching tech is instilling a discliplined mindset. If some instructors are ignoring this from the outset it's just sending the message that it's OK to cut corners. Not good!

I know PADI Tec has it's detractors, but it's the only PADI manual I've seen that explicitly tells students not to proceed if they lack discipline and gives instructors free range to refuse students who they feel aren't suitable, regardless of base diving skills and qualifying criteria.

 

[Marie13]

That is scary. One of the critical aspects of teaching tech is instilling a discliplined mindset. If some instructors are ignoring this from the outset it's just sending the message that it's OK to cut corners. Not good!

I know PADI Tec has it's detractors, but it's the only PADI manual I've seen that explicitly tells students not to proceed if they lack discipline and gives instructors free range to refuse students who they feel aren't suitable, regardless of base diving skills and qualifying criteria.

My instructor does both TDI as well as PADI Tec. He has no issue refusing students. I won’t repeat details but there were a variety of reasons.

 

[lowviz]

...//... AN seems best if the instructor covers a few things from TDI DP that look like they should be in TDI AN for better safety. And a better manual would be nice.

I couldn't agree more!

AN should be a stand-alone course that covers what it claims to be: All the consequences of breathing rich mixes under water up to pure O2. You need to know the consequences, and nobody in any agency ever mentions this:

Pulmonary atelectasis in anesthesia and critical care
Long story short, pure O2 in an alveoli will be consumed by the body and the alveoli will collapse. A bit of nitrogen will prevent this from happening.

https://bjanaesthesia.org/article/S0007-0912(17)44801-X/pdf

“These results confirm both the reduction in lung volumes shown in our previous studies [19, 24] and the results from other studies in which subjects breathed 100% oxygen. This study confirms the work by Green [13], who showed that addition of 20% and 40% nitrogen to oxygen reduced the tendency for alveolar collapse to occur. The present study was more detailed, and showed that there is a log linear effect produced by adding nitrogen to an oxygen mixture up to a concentration of 75 % nitrogen. With the addition of increasing nitrogen to the gas mixture, the reduction in lung volumes caused by breathing oxygen at a reduced lung volume was lessened, and finally neutralized. When lung expansion with deep breaths was encouraged towards the end of each study, several volunteers noticed sharp chest pain which limited their deep breaths. This confirms other experiences [6-10].”

(Is this why 'air breaks' are indicated in O2 treatment?)

On the other hand, DP should (and does) tell you how to properly manipulate said mixes. AP stand-alone is totally valid, but it REALLY, REALLY needs a serious re-work...

 

[lermontov]

with the appropriate gas switch procedure of identifying the bottle by markings and tracing the reg hose back to the bottle there is no reason to distinctly mark the reg. In fact.many good instructors teach not to use a reg distinction because it leads to the complacency of not actual tracing the reg back to the bottle.

i think thats a bit of a circular argument - if someone is thorough enough to tape and mark regs how is it less complacent than just marking a bottle -either way you're checking the markings -if you dong a hypoxic dive with 4-5 bottles then its pretty difficult to see bottle markings anyway.

get a system that works - stick to it

 

[Marie13]

From Friday at Gilboa. Yes, I'm aware there are things to work on, but they're coming along.

 

[rddvet]

i think thats a bit of a circular argument - if someone is thorough enough to tape and mark regs how is it less complacent than just marking a bottle -either way you're checking the markings -if you dong a hypoxic dive with 4-5 bottles then its pretty difficult to see bottle markings anyway.

get a system that works - stick to it

It's not circular logic. There are known cases of people putting a reg on the wrong bottle and breathing it.

 

[lermontov]

It's not circular logic. There are known cases of people putting a reg on the wrong bottle and breathing it.

it could happen if they just had a colour coded system and no further ID but im referring to taping the reg and marking it as you do a bottle - that way you can actually see what it is as you're breathing it -
you have the bottle marked and the reg marked and as long as they both match i cant see an issue