The scuba cylinder, or tank, is arguably the most identifiable part of the diver's kit. The pressurized gas it contains is what makes possible deep, sustained undersea diving that is independent of cumbersome hoses fed by a surface air compressor. These tanks come in a variety of shapes and sizes, in addition to the newer substitutes that are sometimes mistaken for scuba tanks.
The capacity of a scuba tank is the product of its internal volume and its maximum pressure. A medium-sized tank that can handle greater pressure might be able to store more air than a big tank that is rated for lower pressures.
Most scuba tanks are rated between 200 and 300 bar, which translates into between 3,000 psi and 4,500 psi. The typical rented tank is filled to a level closer to 200 bar than 300 bar, even if it can hold more, to limit the wear and tear that filling to the maximum limit would cause.
The other measurement for tanks is internal volume. British and American divers like to do this in cubic feet of air, but the rest of the world prefers to use liters.
Scuba tanks are made of either aluminum or steel, with steel being used for tanks that are rated for much higher pressure.
Most recreational divers use an aluminum 80-cubic-foot tank, pressurized to between 200 and 215 bar. This is the most frequent arrangement encountered by divers who rent scuba tanks from a dive shop and do not make a special request.
The rebreather is often confused with a scuba tank, but it is a different mechanism. Scuba tanks are pressurized bottles of air or a special gas mixture, but a rebreather is both that and an air recycler, getting the most out of a relatively small amount of air.
Article Written By Edwin Thomas
Edwin Thomas has been writing since 1997. His work has appeared in various online publications, including The Black Table, Proboxing-Fans and others. A travel blogger, editor and writer, Thomas has traveled from Argentina to Vietnam in pursuit of stories. He holds a Master of Arts in international affairs from American University.