Abstract: A device to control the rate of flow for valves that mix hot and cold water, the valves comprising a cartridge body (15) with a cylindrical upper neck (18) and incorporating valve means consisting of small superimposed plates. At least one small plate is stationary in the cartridge body (15). The other small plate can be displaced on the stationary plate by an operating lever (16) pivoted on a supporting sleeve (20) able to rotate in that neck (18). The operating lever (16) can be rotated together with the supporting sleeve (20) about a vertical axis "x" to change the proportions of incoming hot and cold water and is capable of oscillations on a transverse pivot (19) borne by the sleeve (20) to change the quantity of water leaving the valve. The control device includes an element (22) for controlling the rate of flow in association with a surface (16a) of the operating lever (16).