Last year we wrote an article on 5 facts about diving with Enriched Air Nitrox. We’ve covered the myths and misconceptions about this special air blend, and how to operate safely underwater.
In this article, we will explore Enriched Air Nitrox in greater depth, including its risks and the science behind it.
How does Nitrox help us dive longer?
Due to the risk of decompression sickness, divers always need to save some of their air supply and time to make safety stops.
Nitrox is composed of more oxygen (most commonly 32%) and less nitrogen (68%) compared to normal air (21% oxygen and 78% nitrogen). This gives us two advantages:
- Lower risk of decompression. The lower concentration of nitrogen slows down the rate of nitrogen deposit build up in the body, extending our dive duration limit by 40% and even up to 100%, depending on the depth. However, this does NOT mean that you don’t need to make decompression stops!
- More oxygen for longer dives. Another obvious advantage is that Nitrox provides larger quantities of oxygen to further sustain the diving session.
Theoretically, wouldn’t it be better to dive with pure oxygen?
While it’s true that the Nitrox blend can extend diving sessions, we should not breathe pure oxygen for extended periods – excess oxygen is toxic and could kill you.
In fact, as discussed in the previous article, greater oxygen levels in Nitrox limits the dive depth. For Nitrox, the depth limit is 34 meters, while regular air can let you descend up to 56 meters.
This is because with a Nitrox tank, the partial pressure of oxygen in your lungs reaches the maximum safety level at 34 meters. The figure is typically 1.4 ATA units.
If the partial pressure of oxygen in your lungs exceeds 1.6 ATA units, you may experience a symptom called oxygen narcosis. Symptoms include anxiety, disorientation, and convulsion. While this may not result in immediate death, the disruption may pose a high risk. Decompression treatment is required to bring blood oxygen down to normal.
What are the disadvantages of Nitrox?
Due to the limitation of the diving depth, it is crucial that you carry a dive computer as part of your standard equipment. Divers who are used to dive into depths allowed by regular tanks may forget about the limitation, and become side-tracked the longer they stay underwater.
A dive computer will remind you of your time limit, air supply, and depth limit. These three figures are especially important if you are not diving with regular compressed air.
Sometimes, it is also necessary to bring one more gear – the oxygen analyzer. A dive computer will not know exactly how much oxygen you have been exposed to. This is because every person consumes oxygen differently, and it’s important to have an oxygen analyzer tailored to your consumption rate.
All these tools – in addition to the cost of a Nitrox tank – will have an additional expense. Bear in mind that a diving session will potentially be more valuable with the cost of Nitrox equipment.