| 摘要 |
A valve 1 that allows free movement of air from a first side to a second side of a barrier layer 2 and which hinders movement of liquid from the first to the second side of the barrier layer has an impermeable membrane 8 attached to the first side of the barrier layer 2 so as to define a chamber 9. The membrane 8 has a plurality of apertures (10, Fig. 2) that allow air to flow into the chamber 9. The valve has an opening 3 in the barrier layer 2 through which air may flow, the opening having a collar 6 extending from the first side of the barrier layer towards the membrane 8. The valve also has means (11, Fig. 3) to prevent the membrane 8 from forming a seal with the collar 6.
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