Nitrox and recreational scuba diving
Reducing the percentage of nitrogen in the breathing mixture through adequate increasing of the oxygen proportion will reduce the possibility of the development the decompression sickness in the course of scuba diving, thus extending the time of dive with scuba without the required increase of the need of decompression stops. While nitrox use for breathing during scuba diving can counteract to the development of decompression sickness, it exposes scuba diver to the increased risk of suffering from oxygen toxicity. Nitrox is a gas mixture consisting of nitrogen and oxygen that may also include other gases. It can be made from normal air as a constituent part of it. Different nitrox mixtures with higher than a normal portion of oxygen is widely used in scuba diving since the reduced amount of nitrogen can be advantageous in extending the affordable dive time the reduction of the risk of decompression sickness (the bends).
No Nitrox mixture can reduce the risk of nitrogen narcosis, because it is attributed to the qualities chemically inherent in oxygen while under pressure. It is the Trimix gas mixtures that can rudece the risk of scuba diving narcosis due to the qualities of helium that is included.
The Wikipedia says the following: Nitrox with more than 40% oxygen is uncommon within recreational diving. There are two main reasons for this: the first is that all pieces of diving equipment that come into contact with mixes containing higher proportions of oxygen, particularly at high pressure, need special cleaning and servicing to reduce the risk of fire. The second reason is that richer mixes extend the time the diver can stay underwater without needing decompression stops far further than the duration of typical diving cylinders. For example, based on the PADI nitrox recommendations, the maximum operating depth for EAN45 would be 21 metres (69 ft) and the maximum dive time available at this depth even with EAN36 is nearly 1 hour 15 minutes: a diver with a breathing rate of 20 litres per minute using twin 10 litre, 230 bar (about double 85 cu. ft.) cylinders would have completely emptied the cylinders after 1 hour 14 minutes at this depth.
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