Enriched Air Nitrox

I needed one more dive to earn my SSI Open Water Diver certification. My instructor decided to do it on nitrox!

What is nitrox? The short answer is that it is any mixture of nitrogen and oxygen. We are all breathing nitrox right now! However, it is generally short for Enriched Air Nitrox, which has a larger percentage of oxygen and a lower percentage of nitrogen.

Why is that important? Oversimplified, excess nitrogen leaks into your bloodstream and can cause an assortment of health-related issues. By reducing the percentage of nitrogen and increasing the percentage of oxygen, you lower your risk of nitrogen narcosis and decompression sickness. You extend the time you can spend at your maximum depth, and reduce or eliminate your need for decompression while ascending.

So, we started off with an academic session. It’s mostly math. And it went by fairly quickly because I had already studied quite a bit of it in anticipation. The interesting thing is, contrary to previously stated benefits, that your maximum depth rises in direct proportion to your oxygen content. In other words, when you elevate your oxygen percentage you also elevate your maximum depth, meaning you cannot dive as deep. If you want to dive deeper than your oxygen percentage will allow, you need to decrease your oxygen percentage. That, then, increases your nitrogen percentage, reduces your bottom time, reduces your no-decompression limit (NDL), and so forth. You have to find the correct balance for your dive.

Thanks to a YouTube video by Lake Hickory Scuba (on Twitter as @lhscuba) I already knew the Magic Circle. That both makes the math easier and speeds up the class quite a bit. Spoiler alert: it is even easier to do in meters.

We then proceeded to select our nitrox scuba tanks. The first thing you do is test the oxygen percentage yourself. You always test it yourself. We calibrated the testing device on atmospheric air first, since we know the oxygen percentage is 20.9%. After testing my nitrox canister, I used the Magic Circle to label my canister. My oxygen percentage was much higher than my instructor’s, but we were not planning a dive below 18 meters anyway.

We then got ready and jumped on a boat to Baring, Olango Island. But, that is for another blog post.