Tank with water-sealable vent

摘要

The top wall portion of the tank has a vent structure including a first tubular projection in communication with the inside of the tank and a second tubular projection of larger diameter mounted on the top wall portion in surrounding relationship with the first tubular projection. A cap is mounted on the first tubular projection, a skirt portion being disposed in the annular space between the first and second tubular projections. Water fill means are provided on the second tubular projection for filling the annular space with water to a depth covering the bottom of the skirt portion of the cap.