A device for regulating flow rate of a gas in a duct, the device including a valve member having an actuator, the valve member being configured in such a manner as to shut off the duct selectively, wherein movement of the valve member is controlled by the resultant firstly of pressure in the duct upstream from the valve member acting on a proximal surface of the valve member, and secondly of a control pressure applied to a distal surface of the valve member of area greater than that of the proximal surface of the valve member, the control pressure being established in an amplification chamber having a feed line and an emptying line, one of the feed and emptying lines presenting a flow rate that is constant and the other presenting a flow rate that is variable and that is controlled by an actuator.