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An Introduction to Technical Enriched Air Nitrox
Enriched Air Nitrox is a breathing gas consisting of air mixed with a higher percentage of oxygen. By adding additional oxygen to the mixture the rate of nitrogen absorption into the body is reduced. "Nitrox" is commonly used by recreational divers for one of two purposes: to increase the length of time one may stay at depth without requiring decompression stops and/or to reduce the risk of decompression sickness by lowering the overall nitrogen levels within the body's tissues.
Technical Enriched Air diving not only involves the use of "nitrox" to increase bottom time. At this level mixtures containing higher percentages of oxygen are used durning stage decompression to reduce the required length of the stops. By reducing the amount of nitrogen contained in the breathing gas excess nitrogen is off-gased more efficiently. Additionally, high partial pressures of oxygen tend to reduce the size of any asymptomatic or "silent" bubbles in the bloodstream, improving their elimination during the stage-decompression process.
In Technical Diving's earlier years many divers used EANx mixes containing realitively low percentages of oxygen (less than 30%) for deep diving. However the reduction of nitrogen loading gained by such practices is virtually inconsequential. Another factor making such practices undesirable is the fact that all oxygen/nitrogen breathing mixes are highly narcotic at depth. As a general rule divers should use a breathing gas containing helium for any dive deeper than 130 feet.
Tech EANx training prepares the diver to use any mixture of enriched air nitrox, including 100% oxygen. Due to the longer time spent in the water by technical divers, greater attention is given to the affects of long term exposure to high partial pressures of oxygen. In addition to remediation concerning avoiding CNS oxygen toxicity problems, students learn to avoid pulmonary or "whole body" oxygen toxicity as well.
Tech EANx courses also provide the diver with in-depth knowledge development concerning diving physics, physiology and decompression theory. Other academic topics include risk management, emergency first-aid procedures and operational procedures.
As technical diving is an equipment intensive activity, a great deal of attention is given to equipment selection, maintanence and configuration. Student Tech EANx divers must also become comfortable with handling the additional gear required to execute these types of dives with minimal risk.
At this level the diver must be extremely comfortable in the water. Generally divers should have logged a fair number of dives in a variety of different enviornments before pursuing this type of training. Execution of basic skills must be smooth and virtually automatic. Quality Tech EANx courses will include basic skills practice, repetition and remediation. Be sure to choose an instructor that starts with simple dives and gradually increases the difficulty of the dives as the course progresses.
Technical diving is certainly not for everyone but for those so inclined this is usually the first step. Take your time, don't rush into this level of diving before you're ready and most of all, have fun.
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