ISO 4126-1:2004 specifies general requirements for safety valves irrespective of the fluid for which they are designed. It is applicable to safety valves having a flow diameter of 6 mm and above which are for use at set pressures of 0,1 bar gauge and above. No limitation is placed on temperature. This is a product standard and is not concerned with applications for safety valves.
When the standard is harmonized under a directive or regulation, the word Harmonized appear. When such an inscription does not appear, it means that the standard is related to / supporting the relevant directive or regulation.