| Nitrox, What is it?
Nitrox is a blend of gases containing the elements Nitrogen and Oxygen. The air we breathe is Nitrox because it contains nitrogen (79%) and oxygen (21%). Enriched Air Nitrox however, is a blend of gases which contains a higher percentage of Oxygen than found in normal air. Essentially any mix greater than 21% up to and including 99 % of oxygen. The first real diving tests using EANx were conducted in the approximate time frame of World War I. During WW II it saw heavier usage and the first open circuit EANx equipment was used. In the year 1979 USA's National Underwater and Atmospheric Administration (NOAA) published EANx diving tables. In the mid to late 90's several certification agencies accepted EANx as approved breathing gas for recreational diving. They then developed courses to train recreational divers how to analyze and plan dives within the recreational limits using blends of 22%-40% of oxygen. Is EAN Nitrox safer than regular air? This is one of the most debated aspects of diving with EAN Nitrox. When people refer to EANx as being safer than air it is usually related to the reduction of Nitrogen in the gas mixture which should minimize the risk of decompression sickness. If used within the proper limits this tends to be a true statement. However, if the EANx is used to dive deeper than the established limits it can actually cause damage due to the partial pressures of the increased Oxygen at that depth. Other factors that can influence the safety of EANx diving are gas blending, analyzing errors, oxygen clean equipment, CNS clock etc. The bottom line is no different than what you were taught in your basic open water scuba course. If you dive within the prescribed limits it is unlikely you will be any more unsafe than diving with regular air. A common myth associated with EANx is that you can dive deeper and stay longer. Although this may in fact be the case, it only works that way if you stay within the prescribed limits for the depth and time related to the particular mix in your tank. For example, a diver can stay at 90 feet using EANx 32 for approximately the same time as a diver using normal air can stay at 70 feet. However if the mixture of Oxygen is increased the Maximum Operating Depth (MOD) decreases. Why should a person dive with EAN Nitrox? There are two basic thought processes regarding diving with EANx. One is as outlined previously, to dive deeper longer but only within the prescribed limits. The second is for safety. In this way, a diver uses EANx but does not push the limits. Instead the diver plans and executes the dive based on tables or computer calculations for normal air. In so doing when the limits for normal air are approached the diver still has a safety reserve due to the minimized Nitrogen in the tank. Remember though, some dives may not be made as deep as with normal air. The depth will be determined by the percentage of Oxygen in the mix and the resulting MOD for that mix. Another factor many consider is that when diving EANx the diver surfaces feeling less drained than with a normal mixture of air. This allows for more dives per day without getting worn out. Tortuga Bay also offers EAN Nitrox tanks for rent.
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