Floating roof tank with sealed gauging pole

A floating roof tank comprising:

• (a) a bottom wall;
• (b) substantially vertical side walls attached to the bottom wall, the side walls defining a top opening;
• (c) a roof disposed within the side walls, the roof having a central portion, peripheral edges and a gauging opening and being shaped and dimensioned to substantially conform to the top opening, the roof being adapted to float on liquid disposed within the tank and having seals disposed at the peripheral edges to substantially seal vapor within the tank;
• (d) a hollow gauging pole disposed vertically within the tank and protruding through the gauging opening in the roof, the gauging pole having side walls with an exterior side and an interior side, the gauging pole side walls being perforated to allow liquid within the tank to flow into the gauging pole and having external seals adapted to seal the exterior side of the gauging pole side walls to the tank roof so as to prevent vapor within the tank from escaping through the gauging opening on the exterior side of the gauging pole side walls;
• and
• (e) an internal float disposed within the gauging pole adapted to float on liquid disposed within the tank, the float having a pair of spaced apart wiper seals adapted to seal the float to the interior side of the gauging pole side walls so as to prevent the escape of vapor from the tank along the interior side of the gauging pole side walls.