Description of SCUBA Air Tanks

Avid scuba divers factor the scuba tank into their dive planning. Capacity, composition and specialty air fill will affect the duration and length of the dive. Divers and dive operators follow consistent practices when using air tanks.

  1. Types

    • Scuba air tanks are pressurized cylinders that are made of steel or aluminum. Tanks are available in varying sizes and three categories of air pressure capacity: low (2400 to 2640 PSI), standard (3000 PSI) and high (3300 to 3500 PSI).

    Sizes

    • The size of scuba tanks determines how much air will be contained at pressure. Tank sizes range from 20 cubic feet to 180 cubic feet. They can be portable as an emergency or spare air supply, or large for longer dives.

    Markings

    • Scuba tanks are imprinted with the tank size, serial number, material code, pressure rating and hydrostatic testing code. Well-maintained tanks also bear stickers from the recent visualization inspection.

    Valves

    • Scuba tanks are usually fitted with a yoke or "K" valve at the top for attachment to the first stage of a regulator set-up. Another type of valve, called a DIN valve, might also be fitted for regulators to be screwed onto the tank.

    Air

    • Plain silver or colored tanks are approved to be filled with air (containing 21 percent oxygen). Specialty-treated tanks can be filled with higher levels of oxygen--these tanks are clearly labeled with "Enriched Air" or "Nitrox" to indicate the specialty air fill.

    Coverings

    • Tanks can be decorated and covered with plastic or mesh to provide protection, and facilitate underwater identification. A tank cap is used to indicate whether it is full (covered valve) or whether it has been used (cap is off).