| 摘要 |
A valve which is to be used as a component of plastics bags and trays for packaging foodstuffs and other perishable goods. The valve consists essentially of a small spherical chamber having an inlet and an outlet. The chamber is made from two hemi-spherical walls having different resilience. In order to close the valve one wall is made to spring into contact with the other wall so that the two walls enter into such close intimate contact that communication between the inlet and the outlet through the valve is prevented.
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