Scuba Diving International (SDI) Computer Nitrox Practice Exam

What does FO2 represent in scuba diving terminology?

1. Fraction of Oxygen in the gas mixture

2. Frequency of Operation for dives

3. Field Oxygenization rate

4. Final Output of the dive computer

The correct answer is: Fraction of Oxygen in the gas mixture

FO2 stands for the Fraction of Oxygen in the gas mixture. This term is crucial in scuba diving, especially when discussing nitrox mixtures, which contain a higher percentage of oxygen than standard air. The FO2 value indicates the proportion of oxygen present in a given gas mixture, which can affect a diver's planning, exposure limits, and decompression needs during a dive. Understanding FO2 is vital for divers using nitrox because it helps them to set their dive computers correctly, plan their dives more effectively, and mitigate the risks associated with oxygen toxicity or hypoxia. In nitrox diving, divers often use gas mixtures with varying levels of oxygen (e.g., 32% or 36% oxygen), and knowing the FO2 helps to determine the maximum operating depth and safe ascent profiles based on the oxygen content of the mixture. In contrast, the other choices refer to concepts that are not standard terminology or relevant to the measurement of oxygen in diving gas mixtures. This underlines the significance of knowing FO2 in relation to both safety and optimizing dive performance.