All transferlines and containers in which cryogenic liquids can be confined must be equipped with safety devices. The safety devices must be designed to work well in all possible operation conditions. The following two principles should be applied:
i.e. more safety devices than required respectively double safety devices
i.e. safety devices based on different mechanisms
Hence, there should always be at least two independent safety devices e.g. a safety valve and a bursting disk connected to separated pipes.
The drawing shows a possible arrangement of the safety devices on a dewar.