| 摘要 |
A non-return valve, comprising a perforate, hollow, conoidally-shaped valve seat defining a cavity of circular cross-section, a hollow, conoidally-shaped diaphragm of elastomerically deformable material and means for securing the diaphragm within the valve seat, so that the entire outer periphery of the rim of the diaphragm is in sealing engagement with the inner periphery of the rim of the valve seat, the diaphragm having an undeformed shape, prior to insertion of the valve member into the valve seat, such that the cross-section of the diaphragm, at least throughout a part of its axial length excluding the rim, is non-annular and bounded by non-circular inner and outer peripheries.
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