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My Take on Nitrox (Enriched Air) Diving
Greg - 1/04/2007 12:00 AM
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Category: Educational
Comments: 11
My Take on Nitrox (Enriched Air) DivingNitrox, or Enriched Air (EAN), is air with a higher concentration of Oxygen. Air is 79% Nitrogen and 21% Oxygen. Nitrox is usually between 30% and 40% Oxygen.

Good things:
- Theoretically decreases your risk of DCS since the Nitrogen percentage is lowered in the air you breath (and DCS is caused by excess Nitrogen bubbles in your body).
- Gives you more bottom time. IE: Using Nitrox with 36% Oxygen, the max bottom time for a dive to 80 feet is 55 minutes vs. 30 feet using regular air.
- Possibly helps with headaches and "the munchies" after diving, but this hasn`t been scientifically tested.

Bad things:
- Nitrox tank fill costs more than regular air fill (usually around $10 vs. $5 for air).
- Equipment needs to be serviced and "made ready" for Nitrox. IE: special lubricant needs to be used to accomodate higher Oxygen percentages.
- Might die from Oxygen Toxicity at lower depths. If you are exposed to a high partial pressure of Oxygen (1.4 ata and greater) you could suffer from Oxygen Toxicity. Nitrox with 36% Oxygen (EANx36) gets you to 1.4 partial pressure of Oxygen around 128 feet (39 meters). With regular air, you would have to dive to around 220 feet (66 meters) to get the same level of Oxygen exposure.

Overall, if you don`t mind the extra cost...and you are diving between 70 and 110 feet, Nitrox is a great choice since it will greatly extend your bottom time. Otherwise, if you are usually diving less than 70 feet, save the money and stick with regular air.

by Greg Davis - Founder of


John_giu - 6/24/2015 10:20 AM
everything else aside, I feel better diving nitrox. Maybe old guys need more O2?
Regardless of the mix you can always set your own conservatism, say to 1.2 in your computer.
As long as you are mindful of %/depth.
NORTHEAST - 6/13/2015 6:40 PM
And buzo yes it does change your bottom time when you compare it to air. Do the calculations. As a matter of fact in some cases it can almost double it.
NORTHEAST - 6/13/2015 6:39 PM
Thanks skin and scuba. I was going to say if I don’t know my next dive destination I usually put a 28% mix in my doubles. I usually dive around 120-140’ and a 28 is a decent mix. Looking at Greg’s post I said to my self shit I could have been using 36???!!!!! Man I’ve been loosing a lot of bottom time. Hahahahahah
Buzo - 1/04/2008 2:02 PM
It doesn`t change your bottom time, just the nitrogen loading at you can dive sooner....i.e.-more dives per day!!
NWKatShark - 11/23/2007 6:58 PM
I`m having a hard time convincing some of my friends to take a Nitrox course. Maybe I should change my stickers from "Voodoo GAS" to "Nitrox".
BeachBubbles - 7/31/2007 12:00 AM
Munchies? After diving? It`s not just me then.
SkinandScuba - 4/04/2007 12:00 AM
Have done all my dives this year on an Optima CCR. This is close to diving only at the depth that is optimum for the gas mix. The difference is that a CCR unit keeps the O2 level at a constant PO2. A SCR unit the PO2 changes the same as diving open circuit with nitrox - The deeper the higher the PO2.
DalelynnSims - 2/25/2007 12:00 AM
A couple comments here. First unless you are being filled using partial pressure method most all dive equipment today is Enriched Air (NITROX) compatible up to 40%. Only after that is O2 cleaning required. Second as an instructor being in the water even at shallow depths the better part of some days NITROX helps provide an extra safety measure. Without students it allows me to get that extra time using my 100cf in somewhere around 2 hours. Like I said I love to dive :-)
Greg - 1/16/2007 12:00 AM
You`re right, so that would be about 96 feet. Looking back at my calculations, it seems I forgot the 1 atm for the surface :) Thanks for noticing that!
SkinandScuba - 1/16/2007 12:00 AM
Your MOD for 36% mix is not 39 Meters. It is 28 Meters. To dive to 39 Meters with a max PO2 of 1.4 your mixture can only be 28% Oxygen content.
Greg - 1/05/2007 12:00 AM
I meant bottom time according to the dive planners (how long you can stay down until you reach Nitrogen limits)...not the amount of time your air will last.