Abstract: A metering valve for extracting a given volume of fluid from a first fluid flow and introducing the thus extracted volume of fluid to a second fluid flow, comprising a stationary valve component provided with a first and a second supply channel and a first and a second discharge channel, and a metering component which can be rotated relative to the stationary valve component and which incorporates a metering channel of the aforementioned given volume. In accordance with the invention, the valve component (2) has a planar surface (9) into which the aforementioned supply and discharge channels open out. The metering component (7) also includes a planar surface (10) which abuts against the planar surface (9) of the valve component (2) and into which the two ends of the metering channel open out.