This part of this standard specifies general requirements for pilot operated safety valves, other than those covered in part 1, irrespective of the fluid for which they are designed. In all cases the operation is carried out by the fluid in the system to be protected. It is applicable to pilot operated safety valves having a valve 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 the temperature.