| 摘要 |
A valve status indicator for indicating that a gate valve is completely open (or completely closed) to permit the passage of a solid pipeline tool through it, consists of a pick up coil wound on a land formed in the valve body. The coil is positioned near a body face 13 along which an element 12, connected to the valve closure member slides so as to form part of the magnetically permeable core of the coil when the valve is nearly open (or closed). An air gap between a shoulder 12' of the element and the land 16 varies with the position of the closure member and consequential changes in the reactance of the coil, in which an alternating current flows, indicate the extent to which the valve fully opens (or closed). <IMAGE>
|
