Scuba Diving International (SDI) Computer Nitrox Practice Exam

When using Nitrox, what is the maximum operational depth referred to?

1. MOD - Maximum Operating Depth

2. PO2 - Partial Pressure of Oxygen

3. SRD - Safe Recreational Depth

4. UDD - Ultimate Dive Depth

The correct answer is: MOD - Maximum Operating Depth

The maximum operational depth in the context of using Nitrox refers to the Maximum Operating Depth (MOD). This is a critical concept when planning dives with Nitrox because it defines the deepest depth at which a diver can safely breathe a specific gas mixture while minimizing the risk of oxygen toxicity. When divers use Nitrox, they are generally concerned about the partial pressure of oxygen that they are exposed to at various depths. MOD is calculated based on the oxygen content of the gas mixture and is intended to keep the partial pressure of oxygen below safe levels, which are typically considered to be around 1.4 ATA for recreational diving. Knowing the MOD helps divers ensure that they do not exceed the depth that would put them at risk of oxygen toxicity. This allows for a safer diving experience while still taking advantage of the benefits that Nitrox provides, such as reduced nitrogen absorption. The other terms do not precisely describe this maximum depth associated with gas mixtures. PO2 relates to the actual pressure of oxygen in the gas mix but does not stand for a specific depth. SRD and UDD are not standard terms used in this context, thus they don't apply here. Understanding MOD is essential for any diver using Nitrox to effectively manage their dive profiles and enhance safety.