Abstract: A sensor apparatus for determining fluid levels and pressures in a fluid-containing vessel wherein the sensor apparatus comprises a mounting member having a fluid passageway positioned therein; a pressure sensor in operative contact with one end of the mounting member and a pressure fluctuation dampening device operatively positioned on the other end of the mounting member. The dampening device comprises an arrangement of fluid passageways arranged so that the fluid passageway through the mounting member substantially perpendicularly intersects a second fluid passageway intermediate the ends of the second fluid passageway with the second fluid passageway being intersected at each of its ends by third and fourth fluid passageways.