Overfill prevention valve

A system, comprising:

• an underground storage tank;
• a drop tube extending into said underground storage tank, said drop tube in fluid communication with said underground storage tank so that fluid passing through said drop tube fills said underground storage tank;
• and
• an overfill prevention valve forming a part of the drop tube, the overfill prevention valve comprising:
• a conduit having a first end and a second end, a conduit wall spanning said first end of said conduit and said second end of said conduit, said conduit wall defining a conduit wall interior surface and a conduit wall exterior surface, said conduit wall interior surface defining a fluid path through said conduit from said first end of said conduit to said second end of said conduit;
• a flapper valve hinged to the conduit, the flapper valve hingeable from an open position to a blocking position, the blocking position obstructing a flow though the conduit;
• a float moveable via buoyancy between a filling position corresponding to the open position of the valve body and an overfill-prevention position corresponding to the blocking position of the valve body;
• a float magnet associated with the float so that a float movement via buoyancy between the filling position and the overfill-prevention position yields a corresponding float magnet movement;
• and
• a valve magnet, the float magnet movement causing a valve magnet movement via a magnetic coupling of the valve magnet with the float magnet, the valve magnet movement triggering a flapper valve movement from the open position toward the blocking position.