| 摘要 |
<p>SUB-SURFACE GATE VALVE The gate for each conduit, of a preferably multiple conduit installation is transversally slidably mounted between full skirts. Dual hydraulic actuators drive a transversally extending rolling cam follow pin along an oblique path to slide the gate open and closed. The actuators have springassisted closure for fail safe operation, the actuator pistons being isolated from well pressure. Where there are two conduits so valved, the actuators for one extend longitudinally upwards from a central bulkhead, and the actuators for the other extend longitudinally downwards. Stem packing for the actuator piston rods is located in the central bulkhead. Modifications for accommodating, e.g. a third valved conduit are described. Also disclosed is a version with two, mutually inverted commonly housed gate valves controlling the same conduit.</p> |
