Abstract: The invention relates to a method for metering a fluid medium by means of a metering device in the form of a piston pump having a cylinder (Z) and a movable piston (3), wherein the cylinder (Z) and the piston (3) form a working space (A), characterized in that in a first method step a given filling quantity of the fluid medium is conveyed into the working space (A), wherein the filling quantity is greater than the predefined quantity to be metered, and in that in a further method step the piston (3) reduces the size of the working space (A) to such an extent that the quantity to be metered remains in the working space (A), wherein at the same time a valve (18, 18?) is opened so that the gas volume separated in the working space (A) and/or the excess fluid medium can flow out of the working space (A) through the piston, wherein to this end the piston (3) has at least one axially running through-channel (17, 17?) which is connected to a return line (19, 19?), and at least the controllable valve (18, 18?) and

Abstract: The invention relates to a method for metering a fluid medium by means of a metering device in the form of a piston pump having a cylinder (Z) and a movable piston (3), wherein the cylinder (Z) and the piston (3) form a working space (A), characterised in that in a first method step a given filling quantity of the fluid medium is conveyed into the working space (A), wherein the filling quantity is greater than the predefined quantity to be metered, and in that in a further method step the piston (3) reduces the size of the working space (A) to such an extent that the quantity to be metered remains in the working space (A), wherein at the same time a valve (18, 18?) is opened so that the gas volume separated in the working space (A) and/or the excess fluid medium can flow out of the working space (A) through the piston, wherein to this end the piston (3) has at least one axially running through-channel (17, 17?) which is connected to a return line (19, 19?), and at least the controllable valve (18, 18?) and

Abstract: A diaphragm pump, in which a fluid moves at least a first piston of a first piston/cylinder system back and forth, the first piston being mechanically connected to at least one other hydraulic piston and the hydraulic piston driving at least one diaphragm by a hydraulic medium.

Abstract: The invention relates to a valve for alternately filling two working chambers (A, B) of a piston-cylinder system (1, 2, 3) of a pump with a fluid, wherein the valve has two valve pump outlets (PA, PB), for connection to the working chambers (A, B) of the pump and has a valve control element (64) that is displaceably arranged in a space of a valve housing (60, 61, 76, 77) and can be movably driven backwards and forwards between two end positions by a fluid, wherein the valve control element (64) has control ducts (67, 82, 83, 84) that co-operate with housing ducts (51, 71, 72, 80, 81) arranged in the valve housing (60) wherein the first valve pump outlet (PA) is connected to the housing ducts (71, 80) and the second valve pump outlet (PB) is connected to the housing ducts (72, 81), wherein in a central region between the two end positions the valve pump outlets (PA, PB) are connected to one another via control ducts (82, 83, 84) of the valve control element (64).