Formula for determining the maximum diving depth using EANx32 mixture (oxygen depth limit). The maximum allowable partial pressure of oxygen for the human body is considered to be 1.6 ATA.
Substituting 1.6 ATA and the oxygen fraction of the EANx32 mixture equal to 0.32 into Dalton’s Crystal, we obtain the equation for finding the absolute pressure (P).
PATA = 1.6 ATA: 0.32 P = 5 ATA
We determine the depth of immersion corresponding to this absolute pressure:
D msw = (5 ATA – 1 ATA) x 10 msw D = 40 msw
The maximum allowable diving depth with EANx32 is 40 msw.
Determination by Dalton’s Crystal of the maximum depth for dive when using EANx36 mixture (oxygen depth limit).
We make an equation to find the absolute pressure (P):
PATA = 1.6 ATA : 0.36 P = 4.44 ATA
Determine the diving depth corresponding to this absolute pressure:
D msw = (4.44 ATA – 1 ATA) xlO msw D = 34.4 msw
If the result is a decimal, it is customary to round down to a whole number for safety. Therefore, the maximum diving depth using EANx36 is 34 msw.
The oxygen limit in technical diving is commonly referred to as maximum operating depth (MOD).
The partial pressure of oxygen (PO2) is calculated in order to determine the oxygen limit of the dive time when using NAITROX mixtures. It is also necessary to know the maximum diving distance and the percentage of oxygen in the mixture.
Now we are going to solve some practical problems and use their examples to continue our “dive” into the theory.
Problem #1: What is the oxygen pressure (O2) at a depth of 30 meters using the EANx32 mixture?
What is the oxygen limit for this dive?
a) Determine the absolute pressure, corresponding to this dive depth: (30 msw : 10 msw) +1 ATA = 4 ATA
b) Calculate the partial pressure of oxygen (FO2) by
formula: FO2 x P = P02 0.32 x 4 ATA = 1.28 ATA
We obtain that partial pressure of oxygen (PO2) with using EANx32 at the depth of 30 m is 1.28 ATA.
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