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  Marc Niegowski's
SCUBA Diving Web


Revised: Thursday, January 14, 2010
02:50 PM



Nitrox is a blend of Oxygen and Nitrogen that differs from the "normal" air mixture of approximately 21% O2 and 79% N2.  It has become very popular with New Jersey wreck divers because with the right "blend" it can safely provide longer bottom times and shorter surface intervals.  Be sure to get proper training before attempting to use any blend of Nitrox, since it can be potentially dangerous if it is misused.

Common mixtures are 32% O2 with 68% N2 and 36% O2 with 64% N2 sometimes called Nitrox I and Nitrox II respectively.

Nitrox may also be called EANx, for Enriched Air Nitrox where the x represents the percentage of O2 in the mixture.
For example: EAN34 would represent a mixture containing 34 percent O2 and 66 percent N2.

Common Formulae
Maximum Operating Depth (MOD) (PO2 FO2) - 1
Best Mix Fraction of Oxygen (FO2) PO2 (Depth + 1)
Best Mix Fraction of Nitrogen (FN2) PN2 (Depth + 1)
Partial Pressure of Oxygen (PO2) FO2 (Depth +1)
Partial Pressure of Nitrogen (PN2) FN2 (Depth +1)
Equivalent Air Depth (EAD) (FN2 (Depth +1) 0.79) - 1
Percent CNS Exposure PO2 Exposure minutes PO2 Exposure Limit

Gas Dose Limits
Oxygen 1.4 ata - 1.6 ata O2
Nitrogen 3.8 ata - 4.0 ata N2

All depths used in the above formulae are represented in Atmospheres Absolute (ata).   Use 33 feet per atmosphere for salt water and 34 feet per atmosphere for fresh water

Most of the above formulae are simply taken from Dalton's Diamond.  If Dalton's Diamond and the above formulae are meaningless to you, then you aren't ready to dive with anything other than normal air.


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