Gas pressure regulation consists of the pressure regulation and the control unit. The pressure regulation module reduces the established system pressure to the desired gas pressure. The electrical control of the pressure regulation module is provided either the machine control unit or through an external memory with programmed controls. The witch over from melt injection to gas injection can take place either as a function of time, stroke or pressure. Either the hydraulic pressure of the injection moulding machine or internal pressure in the mould can be used for the pressure dependent impulse.