| 摘要 |
PURPOSE:To forecast indications of a fault and to prevent occurrence of an accident, by executing a full stroke operation of a valve, deriving a necessary time, an actually measured stroke curve and a reference strock curve based on said curve, and deciding an abnormal state by a deviation of both curves. CONSTITUTION:A stroke sensor 53, a fully opened detector 51 of a valve and a fully closed detector 52 and installed to a valve rod, and a position of the valve is detected. These outputs are inputted to an operating device 42 through a signal transducer 55 and a digital inputting circuit 41, and an acutally measured stroke curve 21 is derived. Subsequently, a reference stroke curve 22 is derived by deriving a reference stroke from a prescribed calculating expression at every constant sampling interval. A deviation of both these curves is compared with a criterion by a deviation comparator provided in the device 42, and when it has exceeded the criterion, it is decided that these are indications of stick, therefore, a fault of the valve is forecast beforehand and occurrence of an accident is prevented. |
