| 摘要 |
<p>A flow setting assembly is provided to permit field adjustment of an electronically actuated flow control valve, particularly a pressure independent characterized control valve (PICCV). In a preferred form, flow can be field adjusted by using a hex tool. Therefore, the maximum flow can be increased or decreased within the valve's adjustable flow range. As with all high close-off valves that employ a ball in their design, the ball passes well into the seat when rotated to the actuator's zero-degree position. Therefore, there is an amount of travel within the first degrees of ball rotation that passes back over this seat. The flow setting assembly eliminates this excess rotation (12°) resulting in a closed position that is offset to improve control resolution and system accuracy. This offset continues to allow the high close-off rating of 200 PSI. MFT actuators electronically adjust to and maintain the 2-10 Volt control signal at the reduced angle, as well as the 100 second running time and feedback signal. On floating point (−3) actuators, the running time is constant but dependent on the overall angle of rotation.</p> |
