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Common Misconceptions of Nitrox (Enriched Air)

By Sarah Bergeson

The label on a tank of enriched air showing the blend and max depth.


After getting their Open Water Certification, a lot of divers choose to continue their education by acquiring an Enriched Air Diver certification.  Though there are a lot of benefits to diving with nitrox, there are a lot of common misconceptions tied to the alternative gas blend.  For safety reasons, it’s really important to understand the difference between a tank of 21% O2 and a tank with a higher percentage.  A specialty course is offered to divers who want to use enriched air, and no diver should dive with enriched air without proper instruction.

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Misconception #1) Your air consumption will improve if you dive with nitrox.  You will hear many certifying agencies talk about how they can dive longer with nitrox.  This does not mean that their tank lasts longer because they are diving with nitrox opposed to a 21% O2 gas blend.  What they mean by “dive longer” is that they can stay at depth longer than someone diving with 21% O2 before flirting with no decompression time.  100% oxygen is toxic after around 10 feet so a higher percentage of oxygen does limit the depth you can safely go.  However, a higher percentage of O2 allows you to stay at a safe depth longer than someone diving on air before having to proceed to a shallower depth due to no decompression times.

To simplify, if you were able to monitor 2 identical divers at equal depths and one diver was breathing off of a tank with 21% O2 and the other was breathing off of a tank with 32% O2, they would run out of air at the exact same time.

Misconception #2) You won’t get “narked” by diving nitrox.  The term “narked” is a slang term referring to nitrogen narcosis.  Defined by Webster’s Dictionary as “a state of euphoria and confusion similar to that of alcohol intoxication which occurs when nitrogen in normal air enters the bloodstream at increased pressure (as in deep-water diving) —called also rapture of the deep”, it’s not only the amount of nitrogen present in the bloodstream that causes some divers to get “narked”.    As we learned in misconception #1, oxygen is also toxic at depth so a more accurate term would be to call it “gas narcosis”.

Misconception #3) As a nitrox diver, you are able to use any available tank on the boat.  Each tank must be analyzed by the diver using the tank to verify the % listed on the sticker is in fact the % indicated on the tank.  The % in the tank will determine your maximum operating depth.  Without knowing the % blend, you cannot know the MOD (maximum operating depth) for a safe dive.  Most tanks are assigned to divers prior to departure based on the list of passengers and the groups the Divemasters have assigned them to.  If you have a nitrox certification be sure to coordinate with your dive shop prior to your arrival.

There are many benefits of diving with nitrox.  Diving with nitrox means your body absorbs less nitrogen on a dive than someone who is diving with a standard air tank with 21% O2.  You’ll have less nitrogen to off-gas during your surface interval so you can get back into the water sooner than someone who is not diving with nitrox.  This can be especially beneficial on live-aboards or other dive vacations where you’re doing several dives a day.

Whether you choose to dive with “voo-doo gas” or a standard tank of air, be sure you follow the suggested recreational dive limits and maximum operating depths for each tank to help avoid any potentially dangerous side effects.

Getting nitrox certified is a quick and painless process – a perfect continuing education certification to get while visiting Hawaii. Since it is strictly classroom work, you can get certified before your first dive with us and enjoy the benefits of nitrox immediately.

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