Scuba Diving Tanks

The diving cylinder, scuba tank or diving tank is used to store and transport high pressure breathing gas as a component of SCUBA (Self-Contained Underwater Breathing Apparatus). It provides gas to the scuba diver through the demand valve of a diving regulator. Diving cylinders are typically filled to either 232 bars or 300 bar and have a volume of 3 to 18 liters or a gas carrying capacity of 850 to 4200 liters (24 to 120 ft³). Cylinders also come in smaller sizes, such as 1.5 and 2 liters, however these are not generally used for breathing, instead being used for things such as dry suit and buoyancy compensator inflation.
Divers use gas cylinders above water for many purposes including storage of gases for oxygen first aid treatment of diving disorders and as part of storage "banks" for diving air compressor stations. They are also used for many purposes not connected to diving.

The term "diving cylinder" tends to be used by gas equipment engineers, manufacturers, support professionals, and divers speaking British English. "Scuba tank" or "diving tank" is more often used colloquially by non-professionals and native speakers of American English.