| 摘要 |
A valve comprises a valve case having a fluid passage and a pair of opposed valve plates turnably disposed on the opposite sides of the fluid passage and each having an abrasion resistant lining over the surface thereof facing the fluid passage. Drive means causes the valve plates to perform a symmetric circular motion at the same time. When the abrasion resistant lining surfaces of the valve plates are positioned upright in parallel to each other, the fluid passage is in its fully open state. The fluid passage can be closed by turning the valve plates inward symmetrically with respect to each other and thereby bringing the opposed end edges of the plates into abutting contact with each other at the center of the fluid passage.
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