Published November 3, 2016 | Diving, Duiken

Scuba diving is one of the most stimulating outdoor activities. It not only helps tone muscles but also aids in breathing. This is a comprehensive physical fitness alternative that also helps improve mind and body coordination. Like with all water sports, it is important to appreciate the importance of safety in scuba diving. One of the most important considerations has to be Nitrox Maximum Operating Depth (MOD). If you are a scuba diver using air, it is important to understand what MOD entails in order to avoid accidents when diving. Here are some of the most commonly asked questions by divers about MOD:

Nitrox Maximum Operating Depth

  • What is Nitrox Maximum Operating Depth (MOD)? In order to understand what MOD entails, you need to appreciate that when diving with air you have to consider the depth of your dive. Nitrox Maximum Operating Depth (MOD) is the depth limit calculated based on the percentage of oxygen in your breathing gas.
  • Why should a diver worry about MOD? It is important to appreciate that while oxygen is good for a diver, it is only up to a point. The higher the concentration of oxygen in your breathing gas the riskier it becomes. Oxygen toxicity is a situation where a diver is exposed to high oxygen concentration levels, which can lead to convulsions. In such a case, you can lose the regulator and drown. It is thus important to determine how deep you dive in relation to the oxygen levels in your breathing gas.
  • How often should I calculate MOD? If you are diving using air nitrox, trimix or pure oxygen, make sure you calculate MOD. This also applies to deep air divers but if you are breathing air for a recreational dive, there is no need to calculate your MOD.
  • How is MOD calculated? Start by calculating the percentage of oxygen in your tank. Once this is done, determine the maximum partial pressure of oxygen with the recommended limit being 1.4 ata. The formula for MOD is:

                  {(maximum partial pressure of oxygen / percentage of oxygen in tank) – 1} x 33 ft

The formula is simple but while you know your MOD, it is also important to consciously stay above your depth limit. Luckily, you can now use a dive computer to alert you in case you exceed your MOD or oxygen partial pressure limit levels. Alternatively, you should clearly write the MOD of the gas in tank so that other divers can alert you in case you exceed MOD. Go ahead and calculate MOD for your next dive and make sure you stay above the depth limit.