Diving with Nitrox

[Kenney]

Hi guys,

I'm knew to diving and I have heard alot about getting cerified to use Nitrox. Are the tanks filled to a higher pressure or do you use less Nitrox than air. This may sound like a dumb question but, what I am trying to figure out it this. If you can stay down longer using Nitrox, do you not run out of air before your time is up or do you usually use two tanks. The deepest I have been so far is 60ft with a single tank and it seemed like I went through my air pretty quick. (aprox. 30min) If I am using Nitrox at say 80-100 feet on a single tank will it really give me much more time. Thanks to all.

 

[SteveAD]

Nitrox does not last longer, it gives you longer NDLs. If gas supply is your controlling factor on a given dive, nitrox will not gain you much, but on repetetive dives, where the NDL is often much shorter you might gain some benefit.

Take the class. Nitrox is a great tool to have in your arsenal. You just need to know when, where, and why to use it.

 

[don Francisco]

The benefit of nitrox is that it could allow more bottom time by extending the no-decompression limits. The other important limit is how low long your breathing gas lasts. Whichever one is shorter is the limiting factor for any dive.

If you're using air so fast that you never run into the NDL, nitrox won't help you. It'll just be more expensive air, and you'd be better served with a larger air supply (bigger tank).

As you progress with your diving career, your air consumption will certainly drop, and at some point you'll find that you're running into the NDL more often, especially on your second dives the same day. When that happens consider using Nitrox to help you extend the bottom times.

I do lots of drift diving and consider a dive perfect when I hit both my air supply and no-deco limits just as I drifting to the end of the reef, and would be ending it anyway.

 

[Maui Bound]

Essentially with a Nitrox blend you are replacing nitrogen with oxygen. Normally air is 79% Nitrogen and 21% oxygen. With a Nitrox 32 blend you have 32% oxygen and 68% nitrogen. So you absorb less nitrogen at depth therefore you can get longer NDL. Absorbing less nitrogen is a good thing. But with anything there are trade-offs. Oxygen toxicity is one of those trade offs. It is one of the first classes we recommend coming out of open water. Enjoy the class and add another tool to your arsenal.

 

[Tortuga68]

For Kenney's benefit - since he mentioned he's new to diving - NDL is No Decompression Limit, ie the amount of time you can dive without needing a deco stop (avoiding a deco stop reduces your risk of DCI (DeCompression Illness) and makes for a safer dive)

Your required SI (Surface Interval - the time between dives) will also be reduced by using Nitrox, when appropriate (as above) - you can't go as deep on EAN (Enriched Air Nitrox) as you can on oxygen due to the PP (Partial Pressure) - hence MB's comment about oxygen toxicity - but that's a whole 'nother thread

As Steve & MB said, it's well worth getting a Nitrox certification as your experience increases - personally I prefer the TDI course (as opposed to say, PADI)

 

[robint]

ditto what they said! Nitrox is great, once you get to the point that your air is lasting longer.

 

[Kenney]

Sounds like a course I need to take if for nothing more than to improve my education. It was sugested that I get Nitrox certified before I went on a wreck dive so I would have more time underwater. However, I started thinking that I'm out of air before my time is up anyway. From what I understand now is that may be true but, my SI will be less and as I become more experienced I will use less air? Thanks again

 

[Blackwood]

avoiding a deco stop reduces your risk of DCI (DeCompression Illness) and makes for a safer dive)

Source?

 

[Tomeck]

Source?

You don't believe?

 

[String]

Source?

I assume he means avoid dives where you have mandatory stops as opposed to not performing a safety stop.

At least, thats what i HOPE he means otherwise i'd have skipped my 45 mins deco today and just come straight up as i was cold, needed the toilet and apparently would have been safer too!