Science Fair Project Encyclopedia
Technical dives may be defined as being to depths deeper than 120 feet / 36 meters. This definition is derived from the fact that breathing regular air while experiencing pressures greater than those at 120 feet or deeper causes a progressively increasing amount of impairment due to nitrogen narcosis. This increases the level of risk and training required. This is a fairly conservative definition of technical diving.
Technical dives may alternatively be defined as dives with durations long enough to require mandatory decompression stops, which may optionally be performed using enriched oxygen breathing gas mixtures such as nitrox or pure oxygen. This definition is derived from the fact that metabolically inert gases, such as nitrogen and helium, in the diver's breathing gas are absorbed into body tissues when breathed under high pressure. These dissolved gases must be allowed to release gradually from body tissues to prevent decompression sickness or the bends. This form of diving implies a much larger reliance on redundancy and training since it is no longer physiologically safe to make a direct ascent to the surface in the case of any problems underwater.
Technical dives may also be defined as being to depths requiring the use of hypoxic breathing gas mixtures such as trimix, heliox, and heliair. This definition is derived from the fact that breathing a mixture with the same oxygen concentration as is found in air (roughly 21%) at depths greater than 180 feet / 55 meters results in a very rapidly increasing risk of severe symptoms of oxygen toxicity. These symptoms can include visual and auditory hallucinations, loss of muscle control, full body seizures, and loss of consciousness.
Technical dives are often referred to dives with a ceiling phohibiting a direct ascent to the surface, it can either be a mandatory stop (decompression obligation) or a physical ceiling (diving under ice, inside a wreck or a cave).
Technical divers may also use various forms of less common diving equipment to accomplish their goals. Typically technical dives involve significantly longer durations than average recreational scuba dives. Technical divers therefore increase their supply of available breathing gas by either connecting multiple high capacity diving cylinders and/or by using a rebreather. The technical diver may also carry additional cylinders, known as stage bottles, to ensure adequate breathing gas supply for decompression with a reserve for bail out in case of failure of their primary breathing gas.
Technical dives often take place when divers go:
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details