Scuba Diving International (SDI) Computer Nitrox Practice Exam

What FO2 does EAN 32 contain?

1. 70 percent nitrogen and 30 percent oxygen

2. 68 percent nitrogen and 32 percent oxygen

3. 90 percent nitrogen and 10 percent oxygen

4. 64 percent nitrogen and 36 percent oxygen

The correct answer is: 68 percent nitrogen and 32 percent oxygen

EAN 32, or Enriched Air Nitrox 32, contains a specific mix of gases used in scuba diving. The term "FO2" refers to the fraction of oxygen in the gas mixture. In the case of EAN 32, the "32" indicates that the mix contains 32 percent oxygen. Since the total composition of a gas mixture must equal 100 percent, the remaining percentage will be the nitrogen content. Thus, if EAN 32 has 32 percent oxygen, the nitrogen content would be calculated as follows: 100 percent - 32 percent = 68 percent nitrogen. This directly correlates with the definition of EAN 32, affirming that it consists of 68 percent nitrogen and 32 percent oxygen. This understanding is fundamental for divers, as choosing the correct gas mixture is crucial for ensuring safe diving practices, planning for appropriate nitrogen absorption, and managing the effects of different gas densities on dives.