| 摘要 |
<p>A valve assembly includes a valve body formed of a cylinder having upper and lower ends with an inlet port at one end, an outlet port on an opposite end and at least one side outlet port. An annular ring element has upper and lower ends on which are formed upper and lower valve seats, respectively, the ring being sealed around its periphery on each end to the valve body. A central portion of the ring connecting the upper and lower ends has at least one and preferably about 6 to 8 openings therethrough in fluid flow communication with the side outlet port.An actuator assembly fitted in the cylinder includes actuators, concentrically fitted actuator rods valve stems and valve plugs for opening and closing the two valve ports by engaging the valve seats on opposite sides of the ring. The rod for the upper valve seat is in the form of a hollow cylinder concentric and coaxial with the actuator rod for the lower seat, the first and second rods being independently actuatable. An independently controllable actuator assembly in the side outlet port includes a valve actuator, an actuator rod attached to and a valve plug for closing the outlet port. The outlet port, when open is in flow communication with a drain open to the atmosphere whereby liquids can be drained by gravity from the space between the annular ring and the cylinder when the side outlet is open.</p> |
