Patent ID: 7673659

Claim:
A system for preventing overflow in a storage tank which is fillable via a nozzle, the system comprising: a fill passage connecting the storage tank to an external atmosphere; a fill fitting comprising: a mounting flange and a sleeve, wherein the mounting flange rests outside the external end of the fill passage and the sleeve fits within the fill passage; a nozzle stop, disposed within the sleeve of the fill fitting, having an internal lip, wherein the inner diameter of the lip is less than the outer diameter of an end of the nozzle; a sealing device, disposed within the sleeve of the fill fitting above the nozzle stop, the sealing device comprising a first inner seal and a second inner seal and a first outer seal and a second outer seal and a hole in a wall of the sealing device between the first inner and outer seals and the second inner and outer seals; a pressure transfer passage having a first end disposed at a specific level within the storage tank and a second end communicating with a hole in the fill passage and a corresponding hole in the fill fitting; wherein the nozzle is in a fill position when the end of the nozzle is in contact with the nozzle stop; when the nozzle is in the fill position, the first inner seal forms a seal around the nozzle below a hole in the nozzle and below the hole in the sealing device and the second inner seal forms a second seal around the nozzle above the hole in the nozzle and above the hole in the sealing device, thereby forming an inner sealing space; when the nozzle is in the fill position, the first outer seal forms a seal between the sealing device and the fill fitting below the hole in the sealing device and below the hole in the fill fitting and the second outer seal forms a seal above the hole in the sealing device and above the hole in the fill fitting.