The pressure regulator maintains the output pressure 20 mbar. + / - 10% input pressure between 25 and 400 mbar. It has a safety valve for low pressure disruption initially closed. The reset occurs automatically when the pressure of consumption points being closed is reached. There is also the possibility that the reset is manual.
Safety valve acts when the output pressure, either by over-consumption or a reduction in the input pressure drops below 15 mbar, by blocking the flow of gas.