Enriched Air Nitrox: Wonder Gas or Hype?
Is it worth getting your nitrox specialty certification? Can nitrox really give you longer dives? Or is enriched air all hype?
If you are thinking about doing your Enriched Air Diver course, but you are not sure whether you are actually going to get any use out of it, or if you’re just curious what nitrox is all about, read on!
How is Diving with Enriched Air Nitrox Different?
Enriched Air Nitrox is air with a higher percentage of oxygen. Regular breathing air contains around 21% oxygen, while nitrox for recreational divers may contain up to 36% oxygen blends. This mix lowers the nitrogen content of your breathing gas so that you collect less nitrogen in your body tissues during your dive.
Myth: Diving on nitrox reduces narcosis.
No, it does not. Studies have shown that oxygen has a narcotic effect just like that of nitrogen, so diving with nitrox will not make any difference – you’ll still get narked.
Does Nitrox Give You Longer Dives?
Yes, nitrox can give you longer dive times!
If you are as happy as a young seal in the water, and you are good on air, you may find you often end up coming up because you are low on no-deco time, while you still have plenty of air left. By lowering the nitrogen content of your breathing gas, nitrox will let you eke out further precious minutes underwater.
How much extra time you get still depends on your depth and your gas consumption, of course, but the right mix of nitrox makes a considerable difference to your available time underwater.
Comparison of no-deco limits based on the PADI Recreational Dive Planner
Nitrox is also handy when you are planning repetitive dives. For example, using nitrox will allow you to take slightly shorter surface intervals - within reason - or give you extra bottom time on your following dives. So if you are going on a liveaboard trip, getting your Enriched Air Diver certification is worth considering!
Myth: Nitrox breathes easier, and your tank lasts longer.
No, nitrox will not lower your gas consumption. If you go through your air quickly and end your dives at 50 bar with oodles of no-deco time remaining, extra oxygen won’t help extend your dive time.
Working on your buoyancy control and relaxing in the water will make a significant difference. You may also want to consider recreational side-mount diving, which allows you to take two tanks with you on your dive and also helps with your buoyancy control.
Why Do I Need to Complete the Enriched Air Diver Course?
The simple answer is to keep you safe! As with any form of diving, you need to know the potential hazards and how to avoid them. Nitrox is so commonly available; it is easy to take advantage of the benefits once you’ve completed your course.
And, of course, if you are planning a special dive and want to make the most of your no-deco time, you will need to be able to calculate the best blend of nitrox for your planned maximum depth. For example, for a dive to 30m, around 32% would be the ideal O2 % to take.
Your dive centre will ask to see your Enriched Air certification before they will let you use nitrox tanks. You will need to analyse the oxygen contents of each tank and work out the maximum safe depth for your dive.
What Are the Dangers of Nitrox?
Enriched Air has depth limits.
Oxygen can be very beneficial to your body when used for surface-level therapy. Still, at depth, higher amounts of oxygen become toxic to your central nervous system, in the worst case causing convulsions and unconsciousness, which can result in death by drowning.
For this reason, you need to know how deep you can safely go with the oxygen percentage in your breathing gas. Luckily this is a straightforward calculation. Even easier using your dive computer - just enter your O2 % and let your dive computer do the work for you!
Oxygen exposure adds up over time (“CNS Clock”)
Exposing your central nervous system to higher partial pressures of oxygen for too long can become a risk when doing repetitive dives on nitrox. A general rule of thumb is not to exceed 180 minutes of dive time per day when using nitrox at a partial pressure of 1.4.
A lower % O2 and shallower depths will give you more time. But, again, your dive computer will track this for you and warn you if you are close to your oxygen exposure limit.
Myth: Nitrox lets you dive deeper.
This is not true! Nitrox will not allow you to go deeper than regular breathing air. The maximum depth you can safely go to on nitrox is dictated by the partial pressure of oxygen at that depth (which should not exceed 1.4), based on the mix of gases in your tank. So your maximum safe depth for regular breathing air (21% O2) is 56.6m, while for 32% O2 it is just 33.75m.
Does Diving with Nitrox Make You Feel Less Tired?
Erm, well, ask any group of divers who use nitrox, and you will get different answers. Personally, no, nitrox or air does not make a difference to me if all other factors are the same (depth, time, conditions). Usually, I use nitrox as a tool to allow me to extend my bottom time when I need to and use air on all other dives.
However, many divers report that diving on nitrox makes them feel less tired. As a result, some may not dive with anything else because of this reason. However, according to studies, there appears to be little evidence to support this.
DAN states that the opposite could be the case as breathing a higher partial pressure of oxygen may lead to oxidative stress, which can cause greater fatigue.
Is Enriched Air Nitrox For You?
Yes! If your no-deco time limits your time underwater, you should consider taking your Enriched Air Diver course. Nitrox is available at dive bases worldwide these days and is a huge advantage when you want to make the most of your dives or when you’re doing several dives a day. It is immensely popular on liveaboards for this reason.
While it will extend your no-deco limits, note that nitrox has other considerations, so paying attention to your course materials and your dive computer is essential.
About the Author
Alexandra fell in love with the underwater world when she was 10 years old. A fish ID expert and keen marine conservationist, she is now a PADI Master Instructor with 12 years of experience working in the Caribbean.
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