| 摘要 |
In a choke valve having flow restricting stages for controlling fluid under relatively high pressure, a rising stem axially moves a valve toward and away from a valve seat opening and closing a fluid passageway through the valve. A plurality of superposed flow restriction members, each closely surrounding the valve stem and having a recess loosely surrounding the valve stem, are disposed on the upstream side of the valve seat. Slots, formed in the valve stem wall, mate and mismate with the flow restriction recesses in response to axial movement of the valve stem and control fluid under relatively high differential pressure across the valve.
|
