| 摘要 |
A device and method for regulating the flow of material through a conduit. The device includes a material flow path having a disk member for closing the material flow path, a material bleed path through the disk member when closed and a member for moving the disk and opening the material flow path. The device can further include an additional piston member for closing the material flow path at a secondary position and having an additional material bleed path therethrough and an additional member for moving the piston and opening the flow path as well as a sleeve member movable within the device for releasing material pressure from both within the device and ahead of the device.
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