Scuba Diving International (SDI) Computer Nitrox Test 2025 – 400 Free Practice Questions to Pass the Exam

The recommended maximum operating depth for EAN36, which is an enriched air nitrox mixture containing 36% oxygen, is approximately 30 meters (100 feet). This depth is primarily determined by considering the increased risk of oxygen toxicity as the partial pressure of oxygen rises with depth. For EAN36, the maximum recommended partial pressure of oxygen is typically capped at 1.4 ATA (atmospheres absolute) for recreational diving.

At a depth of 30 meters, the total pressure is about 4 ATA, and since 36% of that is oxygen, the partial pressure of oxygen would be around 1.44 ATA, which is slightly above the recommended limit, making this a safe threshold under standard dive conditions.

Diving deeper than this increases the chances of experiencing symptoms of oxygen toxicity, which can include visual disturbances, loss of consciousness, or convulsions. Therefore, keeping dives within the specified limits not only promotes diver safety but also aligns with best practices in nitrox diving to minimize the risks associated with higher oxygen levels at greater depths.