NBN EN ISO 11621:2006

This International Standard applies to seamless steel, aluminium alloy and welded steel refillable cylinders of all sizes, including large cylinders (water capacity greater than 150 I).
It provides general requirements and procedures to be considered whenever a cylinder is being transferred from one gas service to another for permanent and liquefied gases.
It does not apply to cylinders for dissolved acetylene, radioactive gases or gases listed in group G of table I.