Abstract: A device which regulates the flow of a medical liquid includes a first and a second body, the first body featuring a first passage fluidly connected to a regulation channel, the second body featuring a second passage which may be positioned at a desired point of the regulation channel and set, during use, in fluid passage communication with the first passage by means of the regulation channel. The device includes a limiter which, once engaged, can no longer be disengaged during normal use of the regulation device, the first body or the second body featuring at least a first stop, and the limiter, when engaged, encountering the first stop in order to prevent the second passage being positioned in a predetermined portion of the regulation channel and/or at the first passage.