Need Help with Nitrox

[teasels10]

If the OP is using the PADI Nitrox tables then he should be sure he has the EAN x32 table instead of the EAN x36 table.

On the EAN x32 table the NDL is 45 mins @ 80'. ppO2 of 1.10. Ending the dive on a pressure group T
On the EAN x36 table the NDL is 55 mins @ 80'. ppO2 of 1.23. Ending the dive on a pressure group V

 

[Dirk P.]

I would like to add one more thing to the entire discussion. When choosing a correct EAN mixture, also take into account other dives you plan to do that day on EAN. This may also affect your NDL on following dives.

 

[Troutmaster]

I agree with Jim and whoever else said you did not get proper instruction in the use of nitrox.

Pick a PPO2, I use 1.4 max working (anything but hanging on a line), look on the chart for the MOD and that is that. If you did not understand the concepts in the class you should have spoken up and the instructor should have noticed and gotten you up to speed.

On an unrelated note, I thought the attempt to bait with the PPO2 1.6 thing was great, as was the restraint showed by the respondant. Deep air debate looking for a thread to hyjack.....

 

[UCFKnightDiver]

Sounds good to me per the rule of 120, it comes out to around 115.

 

[DandyDon]

We are discussing 32% at 80 ft, right...?

I've got a ndl time of 39 mins at 80 ft with my computer

Sure its not set to air?

Yes, it is set to ean 32.

What brand? I don't guess Ohio has any altitude to speak of, not enough to affect a dive computer? I'm at 3300 ft so my Oceanic says 39 minutes. Padi tables say 45 minutes at sea level.

If the OP is using the PADI Nitrox tables then he should be sure he has the EAN x32 table instead of the EAN x36 table.

On the EAN x32 table the NDL is 45 mins @ 80'. ppO2 of 1.10. Ending the dive on a pressure group T
On the EAN x36 table the NDL is 55 mins @ 80'. ppO2 of 1.23. Ending the dive on a pressure group V

Wasn't it established that he is using an online NOAA chart, on a Naui page?

I agree tho, 36% would be a better call. Hold your depth gauge in your hand, set your computer alarm, and don't accidentally sink.

 

[Rogersea]

I'd also advise you to go and get your money back from that instructor. You should not have received a cert if you are still asking questions like this. Tables are not that hard to read and the formula is easy enough. Something seriously wrong here.

Almost as bad as my GF reviewing her nitrox materials and noticing they said to immediately start ascending with a toxing diver who is having a seizure! She knew it did not sound right and asked me.

I have to disagree with him deserving to get his money back. I am aware of others who sit through classes, and can answer the questions while in class can demonstrate all skills, properly manipulate the controls on Dive Computers, use the tables etc etc etc... then once they finish class it is as if they never were exposed to the materials...

It is nice that he asked the question here on the forum, it would have been nicer if he would have re-read his book and purchased a set of tables(if he needs them)...

 

[The Chairman]

So i did my nitrox class a few weeks ago...but need a little clarifying. I want to do my first nitrox dive within the next 2 weeks. I want to dive between 60 and 90 feet. So if im reading the charts right, it looks like i can spend 50 minutes at 80 feet with a 32% mix. I want to have some sort of margin in case i go deeper on accident than planned. If im wrong can someone please help me? Thanks,

Jacob

Hey Jacob,

It doesn't appear that anyone has actually answered your question. Maybe they're not understanding it?

It also appears to me that you are looking for a contingency plan of some sort. Doing that before
you splash only makes sense and I think you are wise to think it through. The how is pretty simple: Just look at the NDL for your next deepest depth. In your case that would 40 minutes @ 90 fsw. It doesn't violate your MOD, so good! If you are diving tables, you should bring them with you as they are designed to accompany you on your dive in case you find yourself even deeper. Of course, diving with a computer obviates that issue and makes changing your dive plan on the fly incredibly easy.

That being said... why do you suppose you have a problem respecting your max depth? This is something that you really need to remedy especially if you intend to move forward with your diving. It's really not that hard to accomplish either. It's simply a combination of buoyancy/trim and your situational awareness. Both of these are skills that should be developed right from OW and they really mark you as an excellent diver.

Of course the deeper dive may be due to an inaccurate dive briefing. Yeah, I get that too. That's why having that contingency depth ready is good for you. I jokingly tell my students that DiveMasters lie. I remember the one telling my AOW class that they would have to bring a shovel to get below 70 fsw. Few noticed that we were at 98 and were quite surprised when I called the dive early.

 

[The Chairman]

I have to disagree with him deserving to get his money back. I am aware of others who sit through classes, and can answer the questions while in class can demonstrate all skills, properly manipulate the controls on Dive Computers, use the tables etc etc etc... then once they finish class it is as if they never were exposed to the materials...

Quite the instructor's nightmare! Learning requires both the student and the teacher to work in harmony. It's easy to vilify an instructor without having been in their class and in fact it's incredibly popular to do that. I don't know all the reasons behind that, but I would suggest that no instructor is perfect. All of us have students who forget or simply get confused after the cert has been earned. Telling posters that they shouldn't have these kinds of questions kind of puts a damper on them asking questions. PLEASE ASK!!!

It is nice that he asked the question here on the forum, it would have been nicer if he would have re-read his book and purchased a set of tables(if he needs them)...

He didn't get it the first (maybe second) time from the manual or the instructor. It's good that he came here and had it presented in a completely different way. It's my belief that ScubaBoard represents a wonderful "after class" learning experience. I just don't understand the need to continually bash instructors that you have not seen teach for whatever reason. It's not very professional.

 

[teasels10]

Wasn't it established that he is using an online NOAA chart, on a Naui page?

I agree tho, 36% would be a better call. Hold your depth gauge in your hand, set your computer alarm, and don't accidentally sink.

Apologies Don, I went to Narc's profile and saw he was a PADI AOW and presumed he would be doing a PADI Nitrox course. Hence my use of PADI cards. ho hummmm !!!

 

[The Chairman]

I agree tho, 36% would be a better call. Hold your depth gauge in your hand, set your computer alarm, and don't accidentally sink.

I don't know Don. I never dive 36% for several reasons...

Unreasonably restricts my depth.
I have way more experience diving 32%.
Reduced exposure to high PPO₂.
Harder to find banked and I try to avoid partial pressure blending.

IOW, I find 32% has a greater range and makes my dive profile more flexible. Sure, I always seem to have more gas than bottom time, but I am WAY OK with having more gas than I need.