Scuba diving cylinders are relatively small, yet very strong tanks that hold large volumes of compressed gas, typically air. Being able to carry your gas supply with you is what defines SCUBA (self containedunderwater breathing apparatus). Whether it’s filled with regular filtered air or enriched air nitrox (higher oxygen and lower nitrogen content) or trimix (three-gas combination) for technical diving, a scuba tank is one of the most important pieces of gear.
Dive cylinders are made from steel and aluminium. Generally in the UK we use steel cylinders as they are negatively buoyany so we need less weight when we are diving.
Cylinders come in a range of sizes and the cylinders we use depend on our size.
In the swimming pool children use 7l cylinders while most of our students use 10l or 12l cylinders. In open water we use 10l and 12l cylinders and occasionally 15l cylinders as needed.