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A buoyancy compensator also called a buoyancy control device, BC, BCD, stabilizer, stabilisor, stab jacket, wing or ABLJ depending on design, is a piece of diving equipment containing a bladder which is worn by divers to establish neutral buoyancy underwater and positive buoyancy on the surface, when needed. The buoyancy is controlled by adjusting the volume of air in the bladder. The bladder is filled with gas from the diver's air tank or from the diver's mouth. ==Features== All BCs will have some features in common: *A ''bladder'' to contain gas which may be added or released during the dive to control buoyancy. *A means of adding gas to the bladder, generally a low pressure ''direct feed''〔European terminology〕 or ''Power Inflator''〔North American terminology〕 that injects gas from a low pressure hose from the diving cylinder's diving regulator or an auxiliary cylinder to the bladder(s) of the BC, that is controlled by an ''inflation valve'', and usually an ''oral inflation'' option. These are usually at the end of a corrugated rubber ''inflation hose''. *A ''vent valve''〔 or ''dump valve''〔 that allows gas to be released or to escape in a controlled fashion from the bladder(s) of the BC. Most BCs have at least two vents: one at the extreme top and the other at the bottom of the BC, for use as air migrates to whichever part of the BC is uppermost, the vent situated at the shoulder is used when the diver is upright and the vent situated nearer the diver's waist is used when inverted. Venting through the oral inflation system is also usually possible. *An ''over pressure relief valve'' that automatically vents the bladder if the diver over inflates the BC by ascending or by injecting too much gas. This is usually a secondary function of the vent or dump valve, and is a necessary safety feature to prevent over-pressure damage. *A means of securing the BC to the diver to transfer buoyancy forces, and to hold the BC in the position intended for its designed function. The BC is typically secured to a diver's torso, either with dedicated straps or as part of a multifunctional system integrated with the bladder or casing. In addition some BCs may include other features: *A tough textile ''casing'' to contain and protect the bladder, and to which most of the other components are attached, with zippers for access to the bladders. *Straps (cambands) to secure back-mount cylinders *A plastic or metal ''backplate'' to support back-mount diving cylinders *A ''crotch strap'' may be included in the harness to prevent the BC from sliding towards the head when the diver is upright and the bladder is inflated. *A ''cummerbund'' is an alternative approach to reduce the tendency for the BC to slide towards the head by providing a close fit around the waist. *''Pockets'' for carrying diving reel, buoys and decompression tables *An ''integrated diving weighting system'' - pockets for lead weights with a quick release mechanism. Integrated weights can eliminate the need for a separate weight belt. *''Trim weight pockets'' for adjusting the position of the diver's centre of gravity to improve diver trim. *''D-rings'' or other anchor points, for clipping on other equipment such as torches, pressure gauge, reels, cameras and stage cylinders *''Emergency inflation cylinders''. This can either be a small (about 0.5 litre) air cylinder, filled from the diver main cylinder, or a small carbon dioxide cylinder. *''Reflective tape'' for better visibility. *''Padding'' for comfort. *A ''redundant bladder'' with associated filling and venting components, as a backup in case of failure of the primary bladder. *''Alternative breathing gas regulator'' connected to or integrated with the inflation/deflation valve assembly. *''Bungees'' to restrain a partially inflated wing 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Buoyancy compensator (diving)」の詳細全文を読む スポンサード リンク
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