The use of excess flow valves is recommended in accordance with fact sheet AD2000 A1 and ASME Boiler & Pressure Vessel Code VIII Div.1 (paragraphs UG 125 through UG 137) when bursting discs or relief valves are being used in series or in combination. Excess flow valves keep the space between safety valve and bursting disc pressureless in case smaller leaks occur. They prevent the build-up of counter pressure. They work with a ball that gets pushed into its seat, if an overpressure occurs, e. g. when the bursting disc opens, thus preventing ventilation and enabling the safety valves to perform as intended. Furthermore pressure manometers and controllers can be connected.