What is the equivalent depth for a 23 msw dive using EAN32?

The concept of "equivalent air depth" (EAD) is essential for understanding diving with enriched air nitrox, as it allows divers to compare the effects of different gas mixtures to those of air. EAD accounts for the reduced nitrogen partial pressure experienced when using a nitrox mixture, which in this case is EAN32 (32% oxygen, 68% nitrogen).

To calculate the equivalent depth for a dive, we use the formula that considers the percentage of nitrogen in air (79% nitrogen) versus the nitrogen percentage in the nitrox mixture. Since EAN32 consists of 68% nitrogen, the equivalent depth will be less than the actual depth due to this reduced nitrogen exposure.

For a dive at 23 msw (meters seawater), we can convert the depth into the equivalent air depth as follows:

1. Calculate Total Pressure at Depth: At 23 msw, the surrounding pressure is approximately 2.3 times atmospheric pressure (1 atm for surface pressure and around 1.3 atm for the water column). This means total pressure equals approximately 2.3 atm.

2. Determine the Partial Pressure of Nitrogen in EAN32: The partial pressure of nitrogen in EAN32