This part of ISO 9809 specifies minimum requirements for the material, design, construction and workmanship, manufacturing processes, examination and testing at manufacture of refillable normalized or normalized and tempered seamless steel gas cylinders of water capacities from 0,5 l up to and including 150 l for compressed, liquefied and dissolved gases. NOTE 1 If desired, cylinders of water capacity less than 0,5 l can be manufactured and certified to be in compliance with this part of ISO 9809. NOTE 2 For quenched and tempered steel cylinders with maximum tensile strength less than 1 100 MPa, see ISO 9809-1. For quenched and tempered cylinders with maximum tensile strength ≥ 1 100 MPa, see ISO 9809-2.