Patent ID: 7089974

Claim:
A fuel storage tank having an overfill protection device (OPD) for shutting off the flow of fuel into the tank via a fuel fill tube when the contents of the tank reach an intended maximum fill level, the OPD including a butterfly valve located within the fuel fill tube and a float, slidably mounted on the outside wall of the fuel fill tube and operatively linked to the butterfly valve so as to rotate it towards the closed position in response to an increasing fuel level in the tank, the float being linked to the butterfly valve by means of an external crank mechanism connected between the float and a pair of trunnion shafts of the butterfly valve so that linear movement of the float is converted to rotary movement of the butterfly valve, wherein a range of movement of the float is limited by a resistor plunger which exerts a preset resistance against the movement of the float as the butterfly valve approaches the closed position, until the buoyancy of the float is sufficient to overcome the resistance, so that the operator is warned that the full shut-off position is approaching.