Abstract: A limit control device for filling a liquid storage tank has a hollow upper body, a plunger tube integral with the upper body, a valve mounted in the hollow upper body and capable of moving between an opening position and a closing position, a valve seat arranged in the hollow upper body and whereon the valve is urged to rest in a closing position, a floater vertically mobile in a chamber arranged at least partially inside the plunger tube. The device is characterized in that the floater is integral with a moving element forming a piston, the moving element being displaced by thrust of the liquid acting on one of its ends.