NAUI Master Scuba Diver 250 Technical Diving LEARNING GOALS In this chapter, you will: 1. Be introduced to the terms presented in bold letters. 2. Learn the differences between traditional sport diving and technical diving. 3. Learn the different types of gas mixtures that technical divers use. 4. Learn the advantages and disadvantages of enriched air nitrox. 5. Read about the types of equipment technical divers use. ADVANCED RECREATIONAL DIVING SPECIALTIES There are specialty diving activities that could be considered technical diving, especially if extended by extreme depth, temperature, or other environmental factors. These are diving activities such as deep diving, penetration wreck diving, ice diving, and cave diving. These diving activities have their own particular hazards, such as nitrogen narcosis, hypothermia, entanglement, limited visibility, and the use of specialized equipment. It is important to obtain thorough training before attempting this type of diving. Extended Range Diving Extended range diving is practiced by many technical divers to depths of about 55 msw (180 fsw). As a deep diving practice, it is rapidly being replaced by trimix described later. Candidates for this type of training must obviously demonstrate good diving techniques and comfort in the 30 to 40 msw (100 to 130 fsw) range. This type of diving is generally taught by diving to progressive depths, with increasing requirements for trainees to demonstrate dive planning, equipment handling, and decompression scheduling (figure 11-1). Technical divers are trained to recognize and understand their personal limitations. Enriched Air Nitrox Today, many divers are seeking the advantages of using alternative breathing gas mixtures. Mixed gas technology is evolving to improve the safety and performance of divers by optimizing a diver’s breathing gas during dives or during various portions of a dive. Gases such as air, nitrox, trimix, heliox, and oxygen are often utilized. It is not uncommon for the technical diver to use several different gas mixtures during a dive. Various mixtures of nitrogen and oxygen are used for dives up to a depth of 40 msw (130 fsw). The term nitrox was initially used to denote a mixture of nitrogen and oxygen. Later, the term enriched air nitrox (EAN or EANx) evolved in recognition of the gas blending process. EAN 32, also known as NOAA Nitrox I, is a gas mixture consisting of 32% oxygen and 68% nitrogen. Another popular mixture is NOAA Nitrox II on EAN 36, consisting of 36% oxygen and the balance nitrogen. It has a depth limit of 33 msw (110 fsw). Custom EANx mixes are used to depths of 51.8 msw (170 fsw). The FIGURE 11-1. TECHNICAL DIVERS PREPARING FOR A DIVE strategy with nitrox is to reduce the nitrogen partial
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