These safety release valves are used to protect the systems from over pressures in the gas trains in the event of sudden overpressures due to closure of solenoid valves
So that the when the line is charged with over pressure than the set pressure, it will allow the release of gas from the system and it is recommended to leave the vent line from this valve safely outside of the building.
These are available in sizes of only 1″ and the pressure setting is available from 20 mbar to 1000 mbar using different set of springs as per requirements.
The maximum allowable inlet pressure of the gas is 1 bar.