Fluid flow taking place from a dispenser and is blocked or released by an electromagnet. The release is effective by a start signal such as a dropped coin or a pushed button. The flow of fluid continues for a time determined by a timing circuit. The timing circuit has a counter which counts the number of start signals by causing counting stages to become energized in dependence of the number of start signals received. Energization of the different counting stages causes a variation in the current supplied to a resistance-capacitance timing circuit, thus varying the timing of the timing circuit to allow the same quantity of fluid to flow for each individual portion dispensed, regardless of the static pressure of the fluid remaining in the dispenser.