The Enriched Air Nitrox or EAN Specialty course was the first class my wife and I took after becoming SSI Open Water Certified. There are many advantages and some disadvantages of using EAN. You need to make sure you understand its limits and why a Dive Computer is so important when you chose to dive with Enriched Air Nitrox.
EAN basically is diving with a higher percentage of oxygen than you normally would if diving with Air. Air is basically 21 percent oxygen and 79 percent nitrogen. EAN can be as high as 40 percent oxygen and only 60 percent nitrogen. The most common 2 mixtures are EAN 32 and EAN 36. This is 32 or 36 percent oxygen in your scuba tank.
Advantages of diving with EAN are:
Greater bottom Time: You absorb less Nitrogen allowing for greater times below the service and less time above between dives.
Improve Safety: You can dive with EAN and use tables as if it was Air and this adds a larger safety margin to avoiding DCS (Decompression Sickness).
Less Fatigue: less Nitrogen and more Oxygen, your body will be less fatigue. In fact you might feel a slight buzz after a dive because of the higher Oxygen levels.
Disadvantages of diving with EAN:
Additional training required due to limitations and dangers
Additional equipment required.
Air fills for EAN are more costly than air.
EAN may not always be available where you want to dive
Additional risk of Oxygen Toxicity
Max depth is less than with air due to oxygen toxicity with higher oxygen levels. However, for the recreational diver limit of 100 feet this doesn’t really come into play as much.
If you feel any of the symptoms of Oxygen Toxicity you need to take action and head up before they get too advance. If they do you will go into convulsions and loss of consciousness. Symptoms of Oxygen Toxicity to look for when diving with EAN are:
Ringing in the ears
Twitchiness muscle spasms
O2 cleaning of you equipment you plan to use with EAN. This is due to the higher levels of oxygen can become combustible with the friction of dirt that can be found on normal equipment used for air. Air is not as clean as EAN and your air equipment will have a higher level of hydrocarbons on it. This is something that you can talk to numerous divers about and each will give you something different. Some divers use the same tanks for air and Nitrox and some have different tanks. I for one carry separate tanks just for Nitrox. It really is your preference for your personal safety.
Newer dive computers are capable of working with either air or EAN in your tank. Older ones required you to get two computers. One for Air dives and one for EAN dives. This is no longer the case if you have a newer computer. The advantage of using the same computer is it makes it much easier to switch back and forth in the same day if you wish and still make sure you are not reaching Nitrogen Saturation. This is due to the computer will recalculate for you. Even though you have a computer it is important to know how to use the tables to protect yourself in case of a computer failure in the field. You will receive a new set of Dive tables to use with diving with Nitrox.
There is another piece of equipment you will need to get if diving with EAN. That is a Oxygen Analyzer to measure the EAN level in the tank before each dive. You will not want to rely on someone else to measure the levels in your tank before a dive. As you can see EAN can be dangerous if not used properly and thus serious injury can result if you think there is EAN 32 in your tank but somehow EAN 36 is in there instead.
In closing my wife and I are glad we got Nitrox certified. Our bodies are not as fatigued after a dive with Nitrox due to less quantities of nitrogen absorbed into our bodies. For anyone serious about diving and wants to spend more time under water the Nitrox is a good first step.
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