Editing Nitrox (section)

==Regional standards and conventions==

===European Union===
Within the EU, valves with M26x2 outlet thread are recommended for cylinders with increased oxygen content.<ref name="EN144" /> Regulators for use with these cylinders require compatible connectors, and are not directly connectable with cylinders for compressed air.

===Germany===
A nitrox cylinder is specially cleaned and identified.<ref name="Becker" /> According to [[European Standard|EN]] 144-3 the cylinder colour is overall white with the letter '''N''' on opposite sides of the cylinder.<ref name="Muller" /> The fraction of oxygen in the bottle is checked after filling and marked on the cylinder.

===South Africa===
South African National Standard 10019:2008 specifies the colour of all scuba cylinders as Golden yellow with French gray shoulder. This applies to all underwater breathing gases except medical oxygen, which must be carried in cylinders that are Black with a White shoulder. Nitrox cylinders must be identified by a transparent, self-adhesive label with green lettering, fitted below the shoulder.<ref name="SANS 10019" /> In effect this is green lettering on a yellow cylinder, with a gray shoulder. The composition of the gas must also be specified on the label. In practice this is done by a small additional self-adhesive label marked with the measured oxygen fraction, which is changed when a new mix is filled.

The 2021 revision of SANS 10019 changed the colour specification to Light navy grey for the shoulder, and a different label specification which includes [[hazard symbol]]s for high-pressure and oxidising materials.<ref name="SANS 10019:2021" />

===United States===
[[File:Cylinder mod.jpg|thumb|right|Cylinder showing Nitrox band and sticker marked with maximum operating depth (MOD) and oxygen fraction (%O<sub>2</sub>)]]
Every nitrox cylinder should also have a sticker stating whether or not the cylinder is ''oxygen clean'' and suitable for partial pressure blending. Any oxygen-clean cylinder may have any mix up to 100% oxygen inside. If by some accident an oxygen-clean cylinder is filled at a station that does not supply gas to oxygen-clean standards it is then considered contaminated and must be re-cleaned before a gas containing more than 40% oxygen may again be added.<ref name="Butler 1992" /> Cylinders marked as 'not oxygen clean' may only be filled with oxygen-enriched air mixtures from membrane or stick blending systems where the gas is mixed before being added to the cylinder, and to an oxygen fraction not exceeding 40% by volume.