IANTD EAN vs PADI EAN courses

[Pullnglide]

If you feel the need to set an alarm, set it for 1.4 and never let it come close to going off. Pay attention to your time and NDL as well as your ppo2. The highest I have ever reached in a recreational dive if I recall is @ 1.2. You will learn the proper procedures for a higher ppo2 in an adv nitrox/deco class which you seem to need quite a bit of more experience until you reach that level of training (I do not know you and not clear on your diving background but it's just the impression I get). Until then dive within your training and limits! Dive safe and have fun!

 

[tursiops]

Remy, you do not get to pick the PPO2. Physics and physiology picks it for you. At 1.4 you are most likely safe from oxygen toxicity caused by depth. Higher PPO2 than that is a gamble.

You may be confused about the toxicity that comes from long exposures to high partial pressures of oxygen. This is not your concern, at your level of diving. Your concern is the toxicity from going too deep for your mixture, and it may happen very quickly once you are too deep.

Nitrox can get you two ways: too deep for the mix, or too long for the mix. The former is controlled by staying shallower than 1.4 PPO2. The latter is more complicated to manage, and highly unlikely in recreational Nitrox use.

 

[UnixMarine]

Rely, your ppo2 is a function of depth and how much O2 is in your mix. If you exceed 1.4 ppo2 while you are actively swimming, you have a substantially higher risk of oxygen toxicity. 1.5 and 1.6 is used to shorten deco times by divers at deco stops. During those deco stops, they are essentially hanging midwater with no excertion.

To to find your ppo2, add the percentage of oxygen for every atmosphere of pressure.

Air is .21 at the surface. Go under and it goes to .42 by 33 ft. Then at 66 it is at .63 and at 99 .84

in turn, 32% is .32 at the surface, at 33 .62 at 66 .95 at 99 it's 1.27, so to stay at or under 1.4 ppo2, you don't want to go any further than 111 ft.

You can generally ask for custom blends, for example, I used .26% for a bail out for my rebreather last dive.

 

[RJP]

You can generally ask for custom blends...

Unless, like Remy, you live on a tiny Caribbean island with limited O2 availability and even more scarce mixing ability. I'm sure there's a place or two that can do custom mixes, but I'm equally sure they are expensive. My own experience on three separate trips to Curaçao is that banked 32% is pretty much the only reasonably available/option. (And even that is often hard to come by.)

The more I think about it... it probably makes a lot of sense for Remy to get some deco training. With nearly every dive having plenty to see in shallow water at the end, doing a handful of mandatory minutes at the end of a deeper dive on 21% is probably less burdensome than tracking down - and paying for EANx. (32% runs $15 or so per tank.) Of course, the same option is available on shallower dives with 32%... once Remy shakes his craving for depth.

:d

 

[kensuf]

I like to explain that PO2's are like taking doses of medicine. I can take 1 advil a day for a month and be fine, but 30 advils at once will cause me problems. Same thing with exceeding certain exposures of oxygen for certain periods of time.

Generic rules, such as "stay below a PO2 of 1.4 for all dives" may cover 95% of all cases, but really it's important to understand what the exposure limits are, what the risks of exceeding them are, and how to minimize those risks.

 

[Colliam7]

I applaud you for thinking about questions before starting your course. As Ray mentioned, you may be over-thinking just a bit, but that is generally a good thing for someone getting ready to take a course - I would much rather have prepared learners, with lots of questions, than silent lumps, sitting in chairs waiting for the experience to end so they can get a card. I think it is good you are taking a class - the idea of setting your PPO limit in your DC to 1.5, simply to get to a somewhat greater depth without the annoying alarm, is probably not a wise decision, and you will (hopefully) understand why after taking the course.

Any one that had taken the IANTD and PADI as well ???, it seems that they are very different since their depth's limitations of each agency course programs are not the same, any hints on this ???

I teach the PADI course, but have not taken the IANTD course, so my comments may be misinformed. But, I would be quite surprised if the two courses were 'very different' in terms of the partial pressure / depth limits. There is fairly general agreement on PPO limits of 1.4 and 1.6 as the 'MOD' and 'CON' limits for 'working' portions of a dive - the Maximum Operating Depth and the Contingency Depth. How the material is presented may vary according to agency, for that matter according to instructor. But the principles of physics and physiology (as tursiops mentioned) should remain the same. As several posters have mentioned, it is preferable to look at the PPO limits, NOT at particular depth limits, because the depth that can be reached while remaining within the 1.4 PPO limit will vary according to the percentage blend. And, even though there is general agreement, abiding by a MOD of 1.4 is not an absolute guarantee of safety, rather it is a relative assurance. An additional resource that you might want to review - before your class - is an article in the DAN Alert Diver journal in December 2013: http://www.alertdiver.com/Oxygen_Toxicity. I now assign this as required reading before my PADI Enriched Air class. (In particular, note the very last paragraph.)

I do think that many enriched air training programs are also putting much less emphasis on 'standard' mixes than before. While there is historical precedent (albeit somewhat arbitrary) for 32% and 36% mixes, many fill operations, at least in the US, have broadened their approach. For example, several years ago I did an informal survey here on SB and found that, particularly along the Atlantic coast, banking of 30% was increasingly common. For years I worked in a shop that did exactly that - we used 30% because it provided divers with better access to many of our coastal wrecks that lie in the 100-120ft range. In addition, we could easily 'blend down' from our banked 30%, to provide a lighter mix if requested.

High volume Caribbean resort operations are less likely to provide alternate blends for individual divers. It is simply a bit more labor intensive than mass production, it does require additional training of staff, and the chance for error is somewhat greater. In contrast, a good LDS with competent good mixing capabilities might be more likely / willing.

Let us know how your course goes. Ask as many questions as you need to feel comfortable with the material.

 

[Lorenzoid]

IMO, at this stage of your diving career, you're "putting the cart before the horse," so to speak....just learn to dive and have fun.

As in just about every other thread he's started.

Recreational-level Nitrox in a nutshell as commonly practiced by us relatively inexperienced divers who don't push any limits:
(1) grab a tank of the standard mix the dive op is offering its recreational divers;
(2) analyze and record MOD and other relevant info per procedure taught in class, based on whatever PPO2 the dive op seems to want you to use, which is probably 1.4;
(3) set your computer accordingly;
(4) don't dive deeper than the MOD.

You could dive for years this way without getting bored.

 

[RJP]

As in just about every other thread he's started.

Recreational-level Nitrox in a nutshell as commonly practiced by us relatively inexperienced divers who don't push any limits:
(1) grab a tank of the standard mix the dive op is offering its recreational divers;
(2) analyze and record MOD and other relevant info per procedure taught in class, based on whatever PPO2 the dive op seems to want you to use, which is probably 1.4;
(3) set your computer accordingly;
(4) don't dive deeper than the MOD.

You could dive for years this way without getting bored.

And if you are like me, you can sometimes get bored with deep/tech/overhead... and really appreciate diving where you simply "grab and go" for 20-30 dives in a week rather than spending a week with V-Planner, a fill station, and 8-10 tanks in order to do only two dives on Saturday.

Was in Bonaire before Christmas and my (similarly deep/tech/overhead) buddy and I did three or four dives a day with no more "dive planning" than throwing tanks in the back of the truck and driving until we got to the desired yellow rock. Actual dive plans consisted of one of us signally "right or left?" when we got to the bottom. It's nice when you can spend more time on any given day planning dinner rather than dives.

In fact, when I posted some info here the day before I left I received a PM from a certain liveaboard captain (I won't reveal his real name... but his screen name rhymes with "Snookie") asking "Bonaire? Isn't that rather pedestrian for you guys?" My response: "Yeah... it's gonna be a blast!"

That said... we did sneak in a quick (90min RT) dive to 200fsw on the windjammer.

 

[Remy B.]

Thanks for the well intended comments, yes the idea is to formulate questions during the course and I already gather some since I'm confuse about the time limits of exposure at different PPO (NOAA) , the depth limits I understand as well as the NDL, like RJP said we are limited here with 32% EAN so I have to work around that.

 

[Searcaigh]

Well Remy hopefully you will learn that by draining a tank with EAN32 to a specific lower pressure then topping up with AIR you will be able to reduce the EAN to say 28% and allow a deeper MOD.

Bit of maths involved, and any half decent IANTD instructor should include this.