A valve (1 0) for sealing and selectively opening a flow path from a water-filled inlet (21 0) to a dry outlet (220) includes a valve body (1 00) having a valve opening (230) surrounded by first and second annular valve seat regions (110, 120). A drainage channel (510, 512)) connects to a space between the first and second annular valve seat regions (110, 120). A plug (300) is displaceable between an open state and a closed state for closing the valve opening (230). The plug has a first annular seal (31 0) for sealing against first annular valve seat region (11 0) and a second annular seal (350) for sealing against the second annular valve seat region (120). The second annular seal (350) is a flexible seal deployed so that it closes prior to closure of the first annular seal (31 0). Second annular seal (3 50) is elastically deformed so as to be pressed into contact with the second annular valve seat (120) when the plug (300) reaches its closed state. This way and upon a spike in the inlet pressure, the second seal will not detach even if the first one does.
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