How Scuba Equipment Works
Scuba Equipment > How Scuba Works • Types of Diving • Scuba at eBay
Scuba Tanks and Regulators
SCUBA divers breath either compressed air (78 percent nitrogen, 21 percent
oxygen) or Nitrox (64-68 percent nitrogen, 32-26 percent oxygen).
Where do they get this air? They carry it in cylinders on their
backs. Each cylinder weighs about 31 pounds, and holds about 80
cubic feet of compressed air.
The cylinder is fitted with a regulator, which reduces the pressure of the gas before it is breathed so the diver's lungs are not damaged. Regulators have two stages. The first stage, attached to the cylinder, reduces the pressure to intermediate levels. The second stage is attached to the first stage by a hose; this stage reduces the intermediate pressure to ambient water pressure. The regulator supplies air when you inhale, but it can also do so continuously when it is set on emergency operation.
Additional parts of the breathing apparatus include small pony tanks, usually attached to the cylinder, which supply extra air for emergency situations; a spare air unit, which allows the diver enough air to ascend from a shallow depth; and a snorkel, which allows the diver to conserve air in his tank while just underneath the surface of the water.
Diving Apparel and Accessories
SCUBA divers wear wet or dry suits for thermal protection. The type
of suit the diver wears will depend upon the water temperature. Wet
suits are for warmer waters, while dry suits are used in colder water.
Divers also attach buoyancy control devices (BCD) to their backs backpack-style. These devices consist of an inflatable bladder and weights, which allow the diver to ascend or descend. They often have pockets and places to hold equipment such as air pressure gauges, depth gauges, and compasses. Many divers also carry dive computers, which calculate the amount of time allowed on the bottom of the ocean.
Other accessories include a mask, a pair of fins, a dive knife for freeing the diver when tangled, and a slate board for communicating with other divers. Additional scuba safety equipment may include a dive light for night diving, safety floats which alert other boats to the diver, and a signaling device to be used if the diver gets separated from his party or boat.