| 摘要 |
A valve device for restricting fluid flow has a hollowed piston member having a closed piston end wall and an open piston seat end. The piston end wall is integral with a second piston wall which extends to the piston seat open end which, in turn, opens into a chamber defined by the piston end wall and second wall. The piston second wall is positioned in slidable contact with a housing interior wall surface and has at least one aperture positioned therethrough for a fluid to flow in or out of the piston from the chamber so that upon the piston being reciprocated in the housing, when the piston seat end is seated in a seat integral with the housing, the at least one second wall aperture is confined by the housing interior wall surface to close the valve to fluid flow and so that when the piston is at a position displaced away from the seat, the at least one aperture is unconfined by the housing so that the valve is open to flow of fluid.
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