A diving cylinder or diving gas cylinder is a gas cylinder used to store and transport high-pressure gas used in diving operations. This may be breathing gas used with a scuba set, in which case the cylinder may also be referred to as a scuba cylinder, scuba tank or diving tank. When used for an emergency gas supply for surface-supplied diving or scuba, it may be referred to as a bailout cylinder or bailout bottle. It may also be used for surface-supplied diving or as decompression gas. neck threads can fail under pressure and can have fatal consequences. and may be carried in a cylinder allocated for that purpose, holding a bottom, travel or decompression gas mixture, and usually includes a reserve. The cylinders are usually carried side-slung (sling-mounted), or side-mounted, clipped on either side of the diver to the harness of the backplate and wing or buoyancy compensator, rather than on the back, and may be left on the distance line to be picked up for use on return (stage dropped). The term "" originally implied that the cylinder was intended for use during a specific stage of the dive, but is also generically used for any independent open circuit scuba set other than back gas carried by a scuba diver. Commonly divers use aluminium stage cylinders, particularly in fresh water, because they are nearly neutrally buoyant and can be removed underwater with less effect on the diver's overall buoyancy. usually when the diver does not carry back-mount cylinders. Skilled sidemount divers may carry as many as three cylinders on each side. The decrease in external volume of the cylinder due to reduction of internal pressure is relatively small, and can be ignored for practical purposes. The international standard for the stamp format is ISO 13769, Gas cylinders - Stamp marking.

Intervals between inspections and tests

A cylinder is due to be inspected and tested at the first time it is to be filled after the expiry of the interval as specified by the United Nations Recommendations on the Transport of Dangerous Goods, Model Regulations, or as specified by national or international standards applicable in the region of use.

  • In the United States, an annual visual inspection is not required by the USDOT, though they do require a hydrostatic test every five years. The visual inspection requirement is a diving industry standard based on observations made during a review by the National Underwater Accident Data Center.

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Sources

  1. CD-ROM prepared and distributed by the National Technical Information Service (NTIS)in partnership with NOAA and Best Publishing Company. Also refer to NOAA Diving Manual.<!---->
  4. Also refer to U.S. Navy Diving Manual. <!---->