A diving cylinder or dive 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 typically have an internal volume of between 3 and 18 litres and a maximum pressure rating of 200 bar to 300 bar, (about 3000 psi to 4500 psi).

The internal cylinder volume is also expressed as "water capacity" - the volume of water which could be contained by the cylinder.

When pressurised, a cylinder carries a volume of gas greater than its water capacity because gas is compressible.

696 (3 x 232) litres (25ft³) of gas at atmospheric pressure can be compressed into a 3-litre cylinder filled to 232 bar.

Cylinders also come in smaller sizes and can be ordered online using our request form.

Sizes such as 0.2, 1.5 and 2 litres, however these are not generally used for breathing, instead being used for purposes such as Surface Marker Buoy, drysuit and buoyancy compensator inflation.

Dive cylinders typically contain (atmospheric) breathing air, or an oxygen-enriched air mix. They rarely contain pure oxygen, except when used for rebreather diving, decompression in technical diving or for oxygen therapy.