Many scuba divers think that diving on enriched air, or nitrox as it’s commonly referred to, allow the diver to dive deeper. This is most emphatically not the case. When you dive with nitrox, you alter the composition of the gas you breathe. Nitrox is an abbreviation of NITROgen and oXygen, and is a mix of these two gases, different from atmospheric air (which is 21% oxygen and 79% nitrox – with insignificant trace amounts of other gases.) What you basically do is add additional oxygen to the mix, so you end up with an “enriched mix” of say 32% or 36% oxygen. (Which of course means there’s less room for nitrogen) The added oxygen content isn’t exactly what we’re after, rather it’s the lower nitrogen percent, which give us certain advantages.
And so what are the advantages of nitrox, if it’s not meant for deeper diving. Well, the lowered nitrogen content in the breathing gas, means you absorb that gas into your body at a slower rate . This is a good thing, because as you may remember – it’s the excess nitrogen in a divers bloodstream that causes decompression illness (or “the bends” as it’s called.) So if you absorb nitrogen much more slowly, you can stay underwater much longer. The time it takes to reach your no-decompression limit is often almost doubled – which is especially useful below twenty meters where a scuba diver often runs our of time, long before he runs low on gas to breathe. In other words, he has to ascend much sooner that he could do, if he was diving on enriched air.
The course entails:
- Analysing the content of a tanks and other pre dive precautions
- A look at various methods of creating/blending nitrox gas
- Safety precautions when handling pure oxygen
- Equipment considerations with enriched air
- Diver responsibilty and air fill logs
- Tank markings
- Safe diving practises on Nitrox
- Oxygen toxicity - warnings, signs and symptoms
- Discussions about dive computer settings
- Optional dives for extra practise of the pre dive checks (as well as just to enjoy the long dive times)
A diver need to be at least 15 years old and be at least a certified PADI Open Water Diver (or the equivalent from another dive training organisation, eg. SSI or TDI.)