This European Standard specifies the requirements for the design, manufacture and testing of safety valves for cryogenic service, i.e. for operation with cryogenic fluids below – 10 °C in addition to operation at ambient temperature. It is a requirement of this standard that the valves comply with prEN ISO 4126-1:2001. In the event of different requirements, this standard takes precedence over that standard. This standard is restricted to valves not exceeding a size of DN 100 designed to relieve single phase vapours or gases. A valve can be specified, constructed and tested such that it is suitable for use with more than one gas or with mixtures of gases. NOTE This standard does not provide methods for determining the capacity of relief valve(s) for a particular cryogenic vessel. Such methods are provided in prEN 13648-3.