Importance

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Abstract

A valve device is disclosed for controlling the delivery of gas from a pressurised source, suitable for use in a pneumatic ejector in sorting apparatus. The device comprises a housing defining a valve element chamber with an input for connection to a source of pressurised gas. A body in which at least one output duct is formed, has an end face in the chamber with a valve seat thereon surrounding the output duct or ducts. A valve element overlays the valve seat, and means are provided for moving the element between a closed position in engagement with the valve seat and an open position spaced from the valve seat. Additional abutment surfaces can be provided for engagement with the valve element on closure. At least one pocket is formed in one of the juxtaposed body end face and the valve element, which pocket forms a cushion of gas as the element moves towards its closed position. The pocket or pockets or additional pocket or pockets can be formed on one or more abutment surfaces spaced from the valve seat. Similar pockets can be formed on surfaces in juxtaposition to form a gas cushion on movement of the valve element to its open position.

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First Claim