| 摘要 |
<p>A membrane type pressure relief valve for packaging containers. The valve comprises a plastic overlay (16, 32, 42) that is formed in a way that causes the center portion (24) of the valve to be pre-stressed when applied to a base sheet (12) or directly to a package wall. The forming of the overlay and its subsequent deformation after application to the base sheet or package wall causes the overlay to act as a mechanical assist to close the valve when valve oil does not fully force the valve closed. <IMAGE></p> |
