Combustion Engineering, Inc.

John H Mutchler

Timothy P Jaeger

Theodore B Farver

William D Marriott

Richard J Matt

Equipment for acquiring diagnostic data from a valve train parameter that changes as a result of the operation of a valve (14) in a process plant is positioned as an auxiliary data acquisition unit (200) in the vicinity of the valve train. A plurality of sensor lines (P3, P4) are connected between the auxiliary unit and locations in the valve train where the parameter changes. The valve is operated so as to generate parameter signals manifested in a first physical form in the sensor lines. In the auxiliary unit, the physical form of the parameter signals is converted into diagnostic signals (E10, E11) having a different physical form. The diagnostic signals are transmitted to a base data acquisition unit (100) that is physically distinct from the auxiliary unit.

Valve diagnostic system including auxiliary transducer box

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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Enfield, CT, United States of America

John H Mutchler