Features
BCs may have the following features:
- A low pressure "direct feed" or "Power Inflator" 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.
- 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.
- 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.
- A harness that the diver wears with straps around the torso and over the shoulders. A crotch strap may be included to prevent the harness from sliding towards the head when the diver is upright and the bladder is inflated.
- A plastic or metal backplate to support diving cylinders
- 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.
- 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 0.5 litre air cylinder, filled from the diver main cylinder, or a small carbon dioxide cylinder. There is a risk that an emergency cylinder is accidentally opened during a dive causing a rapid ascent and barotrauma to the diver. Carbon dioxide, being poisonous at high partial pressures, could be a dangerous gas to have in a BC because the diver may inhale it from the bag underwater., but it is unlikely that this would happen, as the diver would usually be aware that the emergency inflation has been oprerated.
Read more about this topic: Buoyancy Compensator (diving)
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