As a diver you may have heard about, seen others or even dived yourself with Nitrox, but many novice divers may not understand the benefits or even what it is. The primary reason to dive with Nitrox is so that you can stay deeper for longer!
What is Nitrox?
The term Nitrox is derived from the words nitrogen and oxygen which are the gases that make up the air that we breath. Nitrox is a more commonly used term for Enriched Air.
The regular air we breathe is made up of 79% nitrogen and 21% oxygen, and Nitrox refers to air that has been enriched with more oxygen than the normal 21%. EANx is just another abbreviation meaning Enriched Air Nitrox and regardless of which term you use, for recreational diving these refer to all blends with oxygen from 22-40%.
Why add more oxygen to air?
The main reason for adding more oxygen is so that there is less nitrogen. Our bodies use oxygen but nitrogen is inert meaning our bodies do not use it. Nitrogen is what can cause Decompression Sickness (DCS).
As we dive and our bodies are under pressure, we absorb the gases we breathe (liquids under pressure absorb gases – Henry’s Law of physics). We use the oxygen but must not absorb too much nitrogen with out having enough time to dispel or off-gas the nitrogen before coming to lesser pressures. These are the reason we ascend slowly, make safety stops and technical divers make decompression stops.
Decompression theory allows that the deeper we go the faster certain parts of our body absorb gas which is the reason tables or dive computers give us less time at deeper depths. By reducing the amount of nitrogen in the mix we can allow ourselves more time at the same depth than with air!
Why not use a higher oxygen percentage?
Why not dive with only oxygen to entirely eliminate nitrogen? Because oxygen can actually become toxic to us if we breathe it under too much pressure. It can cause what is called Central Nervous System (CNS) toxicity which may cause convulsions.
The deepest you can safely breathe pure oxygen is 6 metres which is why only trained technical divers use it. The depth that the oxygen in regular air 21% can become toxic is 56.7 metres and given the limits for recreational diving, Open Water (18m), Advanced Open Water (30m) and Deep Specialty (40m), is why you may have never heard of this in your previous dive training.
To dive with Nitrox requires a qualifying certification such as the PADI Enriched Air Diver Specialty Course which covers the benefits, considerations and hazards. You will also learn to analyse the mix of a blend in your scuba cylinder and then how to plan your maximum depth and dive time based on this.
What are the benefits of Nitrox?
Diving with Nitrox will really benefit you on slightly deeper wrecks or reefs that do not extend to shallower waters and is a must for serious divers who want to make the most of every dive. Another benefit of Nitrox can be to dive more conservatively by planning the dive as though it was with air but using a Nitrox blend (as long as you keep to the blend’s maximum operating depth) to reduce risks of DCS if you have predisposing factors. Some also feel that it makes you less tired when diving on Nitrox and doing multiple dives per day. Any pro diver would definitely recommend a Nitrox course to get the benefits and help you enjoy diving even more. An Enriched Air Specialty can be done in a day and does not even require dives! Check it out if you have not already!