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August 2022    Download the Entire Issue (PDF) Available to the Public Vol. 48, No. 8   RSS Feed for Undercurrent Issues
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Don't Be Reluctant to Use Air: It's What We Did When That's All We Had

from the August, 2022 issue of Undercurrent   Subscribe Now

From time to time, we see divers get upset when they learn there is no nitrox and they must dive on air. It's no big deal.

Enriched air nitrox (EAN, EANx) was revolutionary when in the late '80s, it became available for sport divers. Some training agencies were suspicious of it, but by the early '90s, it became almost universally used as the de-nitrogenizing semi-permeable membrane system for producing nitrox became standard; it simplified its production and removed the fire hazards associated with the former partial pressure blending using pure oxygen.

So, if you encounter a situation where there is no nitrox, just compressed air, don't fret. Here's how to enjoy the dive:

The first thing to bear in mind: air is actually nitrox 21, that is 21 percent oxygen - naturally. Like other nitrox mixes, it has a maximum operating depth, in this case, 185 feet, due to oxygen toxicity, which may occur with too much time at that depth. Back in the day when only air was available, oxygen toxicity was hardly discussed, mainly because recreational divers rarely ventured deeper than 90-100 feet as they kept their eyes on the U.S. Navy tables to maximize their time underwater.

Next, a helpful tip: Rather than setting your nitrox-rated computer to its "Air" program, keep it in the nitrox mode and set it to "nitrox 21." It will maintain its maximum depth alarm, track your oxygen exposure, and calculate your safe No-deco limit (and deco stops if they are needed).

Don't be afraid to use air. Some of us were sport divers when only compressed air was available, and we got along just fine.

Read more about it in my blog HERE.

- John Bantin

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