| 摘要 |
A pressure responsive unidirectional valve for obturating an outlet opening of a fluid conducting duct comprises an obturating member mounted on said duct and movable between a first position in which it substantially obturates said outlet opening and a second position in which it substantially opens said outlet opening. The obturating member is formed with an up-stream face to which the fluid pressure in said duct is applied and a down-stream face. The valve further comprises locking means including a first part mounted on said obturating member and a second part mounted on said duct, said first and second parts being attachable to each other, when the obturating member is in its first position, with a strength sufficient to retain said obturating member in its first position as long as the difference between the fluid pressure in said duct and any pressure applied to said down-stream face is lower than a given threshold value. The first and second parts of the locking means are detached from each other when the pressure difference oversteps said threshold value to release the obturating member which then moves to its second position and substantially opens the outlet opening, leaving a negligible resistance to fluid flow across the valve. The locking means may be magnetic or mechanic. The valve may comprise means to reset it in the first position after tripping.
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