What gases are primarily considered by Nitrox diving computers for allowable bottom time calculations?

In the context of Nitrox diving, the primary gases considered for calculating allowable bottom time are oxygen and nitrogen. This is due to the fact that Nitrox is a blend of nitrogen and oxygen, with a higher concentration of oxygen than regular air, which typically contains about 78% nitrogen and 21% oxygen.

When divers use Nitrox, they seek to reduce the amount of nitrogen they are exposed to during their dives, which helps mitigate the risks associated with nitrogen narcosis and decompression sickness. Nitrox diving computers utilize algorithms that specifically account for the different partial pressures of oxygen and nitrogen at various depths to determine safe ascent and bottom times.

While carbon dioxide, hydrogen, and helium are related to diving, they do not play a significant role in standard Nitrox calculations. For instance, while helium is used in Trimix diving (which is a blend containing nitrogen, oxygen, and helium), it is not relevant to the Nitrox contexts typically studied in certification courses. Therefore, oxygen and nitrogen are the key factors in allowing divers to calculate their safe bottom times during Nitrox dives.