Patent ID: 7140404

Claim:
A tank monitor apparatus, for a closed tank having a peripheral wall thereof defining an interior of the tank and a tank opening passing through the peripheral wall, the tank monitor apparatus comprising: a sealing closure for the tank opening having an interior surface thereof for partially bounding the interior of the tank when the closure is sealing the tank opening; and a submersible differential pressure sensor including a sensor module and a pressure reference tube; the pressure reference tube having a distal end thereof operatively joined to the sensor module, and also having an opposite vented end thereof attached to the sealing closure adjacent the interior surface of the sealing enclosure in such a manner that the vented end of the pressure reference tube provides operative, sealed fluid communication between the sensor module and the interior of the tank adjacent the interior surface of the sealing closure, when the sealing closure is installed in the tank with the submersible differential pressure sensor extending into the interior of the tank.