Nitrox Question

[A2thaK]

I am taking the PADI Nitrox class this Wed, but have a question for all of you. I have finished the pre-class book/DVD, but still have one question.

Does nitrox last longer than normal air? Since I am a new diver, my air consumption isn't the greatest. So would a 80 cuft tank of EANx32 or 36 last longer than a 80 cuft tank of air? I would think so, due to the higher % of O2, but haven't seen anything that says so. Bu then I think, well even though the air is more efficient, I might just consume the same volume/time.

Also, if a 80 cuft nitrox tank DOES last longer than a tank of air, would I expect it to last as long as a 100 cuft tank of air?

Sorry if this has been posted already, I did not know what to search for.

 

[knotical]

Your consumption of gas should be unchanged. CO2 in your body is what makes you breathe. It's not affected by increasing the O2 in what you inhale.

 

[D_B]

Thats a common question, and your mind would tell you yes .. but it does not last any longer

 

[A2thaK]

Wow that was quick. That was kind of what I expected, but then as you said, my mind was trying to convince me that the greater O2% would be consumed at a slower rate. Thanks for the quick responses!

 

[Rhone Man]

I remember TS&M posting a while ago that the increased oxygen content could result in a lower 'urge to breathe' which might have an incrimental decrease in consumption rates, but it was pretty small. For medical reasons that I now forget, this effect is more pronounced in skip-breathers than the general diving population.

 

[muddiver]

The system that consumes the gas has not changed (that would be you). If you breath at, say, a rate of 3 liters per minute how fast would you empty an 11 liter cylinder of air?

Now since you are still breathing 3 liters per minute, how long will it take to empty an 11 liter cylinder of 32% Nitrox?

Volume is volume, it all lasts the same amount of time.

 

[DCBC]

The gas you breathe has two functions; the first is to deliver a sufficient quantity of Oxygen (consumed by the molecule) and the second involves washing-off the carbon dioxide (which involves volume). The increased O2 content in what you breathe doesn't decrease your breathing rate.

The purpose behind increasing the quantity of O2 in a Nitrox mixture, has nothing to do with the amount of O2 delivered to the OC diver, rather the decrease in the level of nitrogen in the mixture. The disadvantage is an increased PPO2.

 

[Tortuga68]

As has been said, you're rate of consumption won't change, or not significantly anyway

You don't consume anywhere near all of the oxygen you breath even at 21% - your exhaled breath at the surface still contains about 16% O2 ie you have metabolised about 5% of the available oxygen. So adding more O2 to the mix you are breathing won't make you any more efficient

 

[Herk_Man]

The benefits of Nitrox are increased bottom time due to increased NDL and some (present company included) claim a lower amount of fatigue using Nitrox compared to air. Drawbacks to Nitrox include increased cost (sometimes) and limitations on dive depth due to oxygen toxicity.

Having dove both air and Nitrox, at safe depths I highly recommend Nitrox.

 

[Benny-c]

If you breath at, say, a rate of 3 liters per minue

3 Litres per minute.....not bad