Combustion Engineering, Inc.

Richard J Matt

Timothy P Jaeger

Theodore B Farver

John H Mutchler

The system (12',14) includes a target member (78) associated with the stem valve (24) and displaceable therewith, and a camera (68) adapted to be positioned adjacent the stem for generating a video signal of at least a portion of the target member. A marker (80) associated with the valve in the field of view of the camera is provided for defining a reference displacement scale (82) in the video signal. A converter (62) is responsive to the video signal for generating target data commensurate with the absolute displacement of the target. First data interface equipment (42,58,60) is provided for digitizing the sensed pneumatic pressure as the pressure is changed to displace the stem, preferably a full stroke from the open-to-close-to-open positions or vice versa. Second data interface equipment (44,62) is provided for digitizing the target data commensurate with the displacement of the target. In a preferred embodiment, the displacement of the target member (78) is determined by electronically counting the scan lines or sequence of pixels (92-108) associated with the video signal, which are covered or uncovered, or otherwise interrupted, as the target member is displaced.

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Avon, CT, United States of America

Richard J Matt