Specialty of the Month – Enriched Air Nitrox

Specialty Course of the Month
PADI Enriched Air (Nitrox)

There are a several specialties that I believe are almost essential in an experienced diver’s locker; deep diver which qualifies you to dive down to 40m, dry suit if you live in colder climes and Nitrox.

Enriched Air, more commonly referred to as Nitrox, is where the scuba tank on your bank carries a higher percentage of Oxygen then regular air. For recreational divers this can be between 22-40% O2, however many dive centres offer a standard blend of either 32% or 36% Oxygen.

The reason why we increase the percentage of O2 in the cylinder is that it reduces the amount of Nitrogen , and if you recall from your open water course too much Nitrogen is a bad thing for divers and can lead to decompression sickness i.e. nitrogen bubbles form in your body that can restrict the flow of oxygen to your brain and other vital organs. This is more commonly referred to as ‘the bends’ and if untreated can be a life-threatening condition.

So by diving on Nitrox it means that we can spend longer underwater as we are absorbing less Nitrogen. For example under the PADI dive tables you can spend 20 minutes at 30m if diving on normal air which has approximately 21% oxygen. If you were to do the same dive with an oxygen content of 32% then you could spend 30 minutes underwater i.e. 50% longer. If you’ve just paid £100’s or even £1000’s on your annual diving holiday then it makes sense to spend as much time underwater.

There are some potential risks if you are not properly trained. As we descend, the partial pressure of Oxygen increases. At 10m there is the equivalent of 2 atmospheres of pressure, this means that if you had a blend of 32% oxygen then it would equivalent to breathing air with a 64% O2 content, or a partial pressure of 0.64.

If the concentration of Oxygen in your system is too high it can lead to convulsions which in turn can lead to drowning. So as part of the Nitrox course you’ll learn that you don’t exceed a partial pressure of 1.4 O2 content, or 1.6 in an emergency. Likewise if your exposure to oxygen is over a certain amount of time then a similar fate could await you so you’ll learn about equivalent air depths and exposure.

The PADI Enriched Air course teaches you how to calculate your bottom time, exposure time limit to oxygen, how to analyse the oxygen contents of your cylinder and how to calculate your maximum operating depth. Dive computers make life even easier as all you need to do is analyse your tank and set the % of O2 in the settings. Your computer will then automatically calculate your maximum depths and your no decompression limits.

If you speak to people who dive regularly then you’ll often hear them say how Nitrox makes you feel a lot less tired at the end of each day and a feeling that it is generally better for you than constantly loading your system with Nitrogen.

Many dive centres around the world offer free Nitrox to their customers so it doesn’t have to break the bank either.

The Nitrox course is simple to complete and you don’t even need to get wet to get qualified!

Oyster Diving are offering 10% off the Nitrox course if you book before the end of June.

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