| 摘要 |
<p>A gate valve (10) comprises a valve body (12) which includes a stem bore (120) that extends therethrough and a seat bore (126) that extends therethrough and intersects the stem bore generally transversely. A stem (30) is disposed in the stem bore and includes a first stem portion (36) that is sealed to the stem bore, a second stem (42) portion that is sealed to the stem bore, and a gate pocket (128) that is located between the first (36) and second (42) stem portion. First (114) and second (108) seats are each positioned at least partially within the seat bore proximate the gate pocket (128) and each include a flow bore (118, 112) that extends therethrough. The gate valve also includes a gate (100) which is disposed within the gate pocket(128) between the first and second seats, a first actuator for moving the gate from a first position to a second position, and a second actuator for moving the gate from the second position to the first position. One of the first and second positions corresponds to an open position in which a through bore (102) in the gate is aligned with the flow bores in the first and second seats, and the other position corresponds to a closed position in which the through bore is offset from the flow bores. In addition the diameter of the first stem portion is larger than the diameter of the second stem portion.</p> |
