| 摘要 |
PROBLEM TO BE SOLVED: To provide a tank cap capable of reducing the roughness, smoothness and waviness of a seal surface. SOLUTION: The tank cap comprises a handle portion 31, a resin cap body 41, a plate member 61 arranged in the resin cap body 41 in the state of being energized to the opposite direction to a tank side perpendicularly to the direction of the axial length of the resin cap body 41, a circular valve packing 65 having one side face placed on the face of the plate member 61, opposed to a tank, and a negative pressure lip portion 65a abutting on the seal surface 41db of a seal portion 41d protruded from the outer periphery of the other side face of the valve packing 65 and protruded from the inner periphery of the resin cap body 41. The seal portion 41d consists of a circular disc protruded almost perpendicularly to the cylindrical portion 41a and its inner periphery edge 41da is provided with a cylindrical bottomed protruded portion 41e protruded to the opposite side to the tank side. |
