- Device (11; 111) for metering one or more powders (A, B) in order to produce a flow of powder(s) and of a carrier gas at a given volume flow rate, the device (11; 111) comprising: - at least a first source adapted to supply a first flow including a first powder and a first carrier gas at a volume flow rate substantially equal to the given volume flow rate, - a source of a carrier gas adapted to supply an adjustment carrier gas flow at a volume flow rate substantially equal to the given volume flow rate, - an outlet junction for sending said flow of powder(s) and of carrier gas, - at least a first proportional valve including an inlet connected to the first source to receive the first flow, a first outlet for selectively sending a volume percentage X1 of the first flow to the outlet junction, and a second outlet adapted to send a volume percentage 100-X1 of the first flow, the percentage X1 being between 0% and 100% inclusive and representative of a setting of the first proportional valve, - an adjustment proportional valve including an inlet connected to said source of carrier gas by a first connecting line to receive at least a fraction of the adjustment carrier gas flow, a first outlet adapted to send a volume percentage Y of said fraction, and a second outlet adapted to send a volume percentage 100-Y of said fraction, the percentage Y being between 0% and 100% inclusive and representative of a setting of the adjustment proportional valve, and - a control system adapted to control at least the first proportional valve and the adjustment proportional valve and configured so that the flow of powder(s) and of carrier gas has a volume flow rate substantially equal to the given volume flow rate, the device (11; 111) further comprising: - at least a first recycling system for recycling at least a part of the first flow, and - at least a first recycling junction connected, upstream, to the second outlet of the first proportional valve to receive the percentage 1 -X1 of the first flow and to the first outlet of the adjustment proportional valve to receive the percentage Y of said fraction and, downstream, to an inlet of the first recycling system, the control system being configured so that the inlet of the first recycling system receives a volume flow rate substantially equal to the given volume flow rate, and the device (11; 111) being characterized in that it includes an aspiration and filtration system connected to an outlet of the first recycling system and a member for regulating a head loss between the first recycling system and the aspiration and filtration system, the regulator member being adapted so that a pressure in the outlet junction and a pressure in the first recycling junction are substantially equal to one another. - at least a first source adapted to supply a first flow including a first powder and a first carrier gas at a volume flow rate substantially equal to the given volume flow rate, - a source of a carrier gas adapted to supply an adjustment carrier gas flow at a volume flow rate substantially equal to the given volume flow rate, - an outlet junction for sending said flow of powder(s) and of carrier gas, - at least a first proportional valve including an inlet connected to the first source to receive the first flow, a first outlet for selectively sending a volume percentage X1 of the first flow to the outlet junction, and a second outlet adapted to send a volume percentage 100-X1 of the first flow, the percentage X1 being between 0% and 100% inclusive and representative of a setting of the first proportional valve, - an adjustment proportional valve including an inlet connected to said source of carrier gas by a first connecting line to receive at least a fraction of the adjustment carrier gas flow, a first outlet adapted to send a volume percentage Y of said fraction, and a second outlet adapted to send a volume percentage 100-Y of said fraction, the percentage Y being between 0% and 100% inclusive and representative of a setting of the adjustment proportional valve, and - a control system adapted to control at least the first proportional valve and the adjustment proportional valve and configured so that the flow of powder(s) and of carrier gas has a volume flow rate substantially equal to the given volume flow rate, - at least a first recycling system for recycling at least a part of the first flow, and - at least a first recycling junction connected, upstream, to the second outlet of the first proportional valve to receive the percentage 1 -X1 of the first flow and to the first outlet of the adjustment proportional valve to receive the percentage Y of said fraction and, downstream, to an inlet of the first recycling system, the control system being configured so that the inlet of the first recycling system receives a volume flow rate substantially equal to the given volume flow rate, and the device (11; 111) being characterized in that it includes an aspiration and filtration system connected to an outlet of the first recycling system and a member for regulating a head loss between the first recycling system and the aspiration and filtration system, the regulator member being adapted so that a pressure in the outlet junction and a pressure in the first recycling junction are substantially equal to one another.