Nitrox Diving Explained

Diving with Nitrox is increasingly widespread nowadays. This article will explain what Nitrox is and why you should use it.

The oxygen that we all breathe is one of the most common elements in the universe and is vital for life. The mixes used in recreational diving have higher oxygen concentrations, such as Nitrox.

Nitrox

The normal air that we breathe contains 21% oxygen with the rest 79% being nitrogen (not including the 1% other gases). Nitrox (also called EANx or Enriched Air Nitrox) has a higher oxygen concentration – between 21% and 40%. This gas has been used for a long time by the Navy, diving companies etc. Now it is widely recognized as the preferable gas mixture for recreational diving, especially for diving in depth between 18 and 40 meters, where its effectiveness is the highest.

Why Nitrox?

The main advantage of using Nitrox is the extended bottom time – the time you can spend at a certain depth before having to make a decompression stop.

The key factor when achieving this time is the amount of nitrogen you have taken in your organism while being under pressure.

When using a standard PADI / DSAT diving table, diving at 21 m (70 feet) will require a decompression stop after 40 minutes (given no previous dives).

By replacing a portion of the nitrogen in your dive tank and increasing the total oxygen concentration in the cylinder to 32%, you can extend the time without decompression stops up to 60 minutes.

However, that doesn’t mean that all your dives will last longer. The duration of the dive also depends on your personal gas consumption (SAC rate), the diving depth, the temperature of the water, boat rules etc.

Another misconception is that Nitrox allows diving at greater depth. If you over-expose to oxygen – because of exceeded depth or time limit – this can lead to serious complications.

Advantages of diving with Nitrox:

Longer bottom times by no-decompression diving
Shorter decompression times
Shorter surface intervals
Decrease of residual nitrogen in the body after the descent
Reduced likelihood of decompression sickness
Decreased probability of nitrogen narcosis

Are there any dangers?

You should know exactly what is in your tank, analyze it personally, and plan your dive carefully before Nitrox diving. The use of the wrong mixture or cylinder can be very dangerous. The different percentage mixtures have different maximum operating depth (MOD), which you should take into account when choosing your mixture according to the dive you are about to do.

WARNING

Do not use Nitrox without a preliminary gas analysis.
Do not use Nitrox with more than 40% oxygen if you are not certified for this.

Sometimes there are several tanks with different mixtures on the diving boat, depending on the personal specifications of the divers and the requirements of the site. Thus, mistakes can easily happen and the consequences might be fatal. You can avoid that by correctly labeling your dive tank.

Labeling of the cylinder

The nitrox cylinders must be labeled with the usual green and yellow EANX/Nitrox labels. However, this is not always the case and sometimes there is no marking on the tanks. It is important that you mark your dive tank with the appropriate label to avoid any mistakes!

The labeling of diving tanks must include: