The valve has: a body projecting an inlet duct and an outlet duct; a seat in the inlet duct and cooperating with a sealing ball; a helical spring between the sealing ball and a supporting ball; a rotor mounted on the body and having a cam surface, cooperating with the supporting ball; a locking member having a magnet and housed within each cavity of the rotor, and to be moved between operative and inoperative positions; a spring in each cavity and forcing the locking member into the operative position; and retention housings, each of two of the latter being opposite to each other, receiving one of the locking members in the operative position, in a rotational position of the rotor.