ISO 17879:2017 specifies the design, type testing, marking and manufacturing tests and examinations requirements for self-closing cylinder valves intended to be fitted to refillable transportable gas cylinders which convey compressed, liquefied or dissolved gases. NOTE 1 The main applications for such self-closing cylinder valves are in the calibration gas and beverage industries. ISO 17879:2017 covers the function of a self-closing cylinder valve as a closure. NOTE 2 Requirements for standard cylinder valves are given in ISO 10297. Requirements for quick-release cylinder valves are given in ISO 17871. ISO 17879:2017 is not applicable to self-closing cylinder valves for cryogenic equipment, for portable fire extinguishers, or for liquefied petroleum gas (LPG). NOTE 3 Requirements for valves for cryogenic vessels are specified in ISO 21011 and at a regional level, for example, in EN 1626. Requirements for valves for portable fire extinguishers at a regional level are specified, for example, in EN 3 series. Requirements for self-closing LPG cylinder valves are specified in ISO 14245. NOTE 4 Additional requirements for pressure-relief devices might be specified in international/regional regulations/standards.