Home >> Science & Nature >> Science

How to Calculate Equivalent Air Depth

Equivalent air depth is a measurement that approximates the decompression requirements of nitrogen/oxygen mixtures of breathing gas when the proportions of the two components are different than those found in normal breathable air. It is the depth of a dive at which the air that a diver is breathing would have the same partial pressure of nitrogen as normal air would at the depth that the diver is located at the time. The equivalent air depth of a nitrogen/oxygen mixture is a function of the amount of nitrogen in the mixture and the depth at which it is being used.

Things You'll Need

Calculator

Instructions

- 1
  Determine the percentage of nitrogen in your nitrox mixture and divide it by 100. For example, if your mixture contained 64 percent nitrogen, you would divide 64 by 100 to get 0.64.
- 2
  Determine the depth of the dive in feet and add 33 to it. For example, if you were diving down 90 feet, you would add 33 to 90 to get 123.
- 3
  Divide your result from Step 1 by 0.79. For the above example, 0.64 / 0.79 = 0.81.
- 4
  Multiply your result from Step 2 by your result from Step 3. For the above example, 123 --- 0.81 = 100.
- 5
  Subtract 33 from your result from Step 4 to obtain your equivalent air depth in feet. For the above example, 100 ' 33 = 67 feet.

Science