Abstract: A so-called "visual" flow-regulation system ensuring a constant flow-rate and presenting an impenetrable barrier to air-bubbles even after completion of the perfusion, the system comprising a central tube on which a sleeve is arranged to slide, the sleeve being provided with a float and further comprising a flexible diaphragm intended to cooperate with the extremity of the fixed central tube, the unit imparting to the liquid passing through it a downward and then an upward movement.