Patent ID: 7935072

Claim:
A system for arresting the flow through an extracorporeal fluid circuit comprising: at least one active flow cut-off member coupled to a length of deformable tubing forming part of said extracorporeal fluid circuit, said cut-off member having at least one movable portion and being actuatable between an open condition, said open condition allowing the fluid to pass through, and at least one closed condition, said at least one closed condition preventing the fluid from passing through said length of deformable tube; an actuator connected to said cut-off member for moving at least said movable portion; and a monitoring unit coupled to said actuator and capable of: causing a movement of the movable portion of the cut-off member towards said closed condition; determining a value of at least one dynamic parameter associated with a motion of said movable portion during said movement; and checking that the value assumed by said dynamic parameter satisfies a criterion of acceptability; wherein said at least one dynamic parameter is determined in relation to a first position of the movable portion, said first position being intermediate between a rest position and a working position, said movable portion being in the working position when the cut-off member is in the closed condition, and said movable portion being in the rest position when the cut-off member is in the open condition; and wherein said at least one dynamic parameter is configured to provide information about a condition of motion of said movable portion and is selected from: p 1 , corresponding to a time interval dT taken by the movable portion to move between a first predetermined position and a second predetermined position, at a distance from said first predetermined position, p 2 , corresponding to a speed of said movable portion at said first predetermined position, p 3 , corresponding to an acceleration of said movable portion at said first predetermined position, p 4 , corresponding to a function F(p 1 ) of said parameter p 1 , p 5 , corresponding to a function F(p 2 ) of said parameter p 2 , p 6 , corresponding to a function F(p 3 ) of said parameter p 3 , and p 7 , corresponding to a function of two or more of said parameters p 1 , p 2 , p 3 .