Process for detection of stick-slip movements in control valves or gas regulators

摘要

The process has a number of steps. First determination of a first state variable from the measured displacement of a movable part (141) with a section (143) capable of slipping. Then calculation of a second state variable from a second measured displacement, with the device operating normally, ie. no stick slip condition. A value for a second state variable can then be predicted from a first measured state variable and an equation determined from the previously determined first and second state variables under normal operation. If there is a disparity between the measured second state variable and the predicted state variable then this can be said to be due to abnormal sliding of the sliding section (143).