Abstract: In a method for diagnosing control system of a process engineering plant having a plurality of actuating units for setting a process fluid and a central unit, at least one actuating-unit-specific control raw datum, such as a setpoint value, an actual value, a setpoint-actual difference value, or a control value, is detected; a particularly local diagnosis code is generated by one of the plurality of actuating units based on the at least one detected control raw datum; the diagnosis code is transmitted from the actuating unit to a central unit; a local diagnosis code, is transformed into a global diagnosis codes; a logical condition for a diagnosis deduction logic is defined such that when the logical condition is applied to at least one diagnosis code, the diagnosis deduction logic determines a predetermined deduction result; and a deduction result is determined based on the at least one diagnosis code.

Abstract: Methods for testing the operability of a safety valve, as well as a solenoid valve for triggering a safety valve, and corresponding devices are proposed. The safety valve has a solenoid valve which is used to vent the pneumatic actuator in a safety case. Initially, a safety case is triggered. The position course of the valve member is recorded, and the time required until the safety position is reached is compared with a reference value. From this, it can be reliably concluded whether the assumption of the fail-safe position was caused by the solenoid valve or by the positioner. The measured values of pressure sensors can also be taken into account and allow further diagnostics to be carried out if operability is not assured. If the result of the test is positive, maintenance intervals can be optimized.

Abstract: A positioner for a process plant, such as a chemical plant, a power plant, or a food processing plant, may include a control valve for controlling a process fluid flow of the process plant, a pneumatic actuator for actuating the control valve, and positioner electronics for determining and providing a pneumatic control signal for the actuator based on a control variable. The positioner electronics may include a signal receiving interface for receiving the control variable. The positioner electronics may include a computing device configured to determine at least one simulation parameter that characterizes a signal response of the positioner to a received control variable. The positioner electronics may include a signal output interface for outputting the at least one simulation parameter.

Abstract: The invention relates to a method for detecting a spring breakage in a preloaded drive of a control valve. The method is based on the fact that the pressure which must be applied to achieve a certain valve member position falls significantly after the breakage or failure of the spring. The breakage of a spring in a preloaded drive can thus be detected reliably using the sensor system already present in the control valve, moreover without having to disrupt or interrupt operation.

Abstract: The disclosure provides a method for testing a solenoid valve for triggering a safety valve having a single-acting fluidic drive and a positioner. The drive fluid pressure is increased by a first pressure difference. An attempt is made to switch the solenoid valve to the safety position. The drive fluid pressure is measured at a specified point in time that is selected such that the pressure in the drive fluid lowers at most by the first pressure difference. If the pressure in the drive fluid is higher than a reference pressure at the specified point in time, the functionality test of the solenoid valve is failed. The lowering of the pressure in the drive fluid is monitored over a defined period of time to make conclusions regarding the pressure generating system. The pressure does not fall below the operating pressure so the position of the valve member remains constant.

Abstract: A method is proposed for establishing termination criteria for a partial stroke test on a safety valve, including: a) A partial stroke test is carried out when the safety valve is operational. b) Position of the valve member and pressure in the drive fluid are recorded. c) A first relation is derived, which relates position of the valve member, time, pressure of the drive fluid, and/or control deviation to one another. d) This relation is defined as a safety valve reference curve. e) A second relation is defined, which has a predetermined distance from the reference curve. f) Termination criterion include: If the partial stroke test is repeated on the same valve, the same data are recorded and a third relation is derived for the reference curve, the partial stroke test is not passed if the third relation has a greater distance to the reference curve than the second relation.

Abstract: For determining the operability of a fluid driven safety valve, a method comprising the following steps is described: A partial stroke test is performed on the safety valve, resulting in a stroke-pressure curve. The stroke pressure curve is extrapolated (330, 340) beyond the measured range (360) up to the safety closing position (350). From the extrapolated stroke-pressure curve, the closing pressure reserve (320) can be determined. In this way, the functionality of the safety valve can be checked during operation.

Abstract: A method for diagnosing possible causes of changes in at least one control valve, in a plant of which the control valve is a part, or in a process which is carried out on the plant is proposed, wherein at least in a first and in a second time interval the position of the actuator is detected, an operating point or operating range is determined from the first and from the second time interval, these are compared, and possible causes of changes in the at least one control valve, in the plant or in the process are diagnosed from detected differences. Such a diagnosis does not require any additional sensors and makes it possible to detect emerging problems or undesirable developments solely from the operating state of the valve.

Abstract: In a diagnostic method for a positioning device of a process plant, such as a chemical plant, a food processing plant or the like, which includes an actuator (e.g. pneumatic or electric actuator) with a drive shaft and a positioning armature, such as an actuator valve, with a positioning shaft, the drive shaft and the positioning shaft being connected to each other in a rotationally fixed manner (e.g. by a detachable coupling interface and/or a positive-locking torque coupling, such as a claw coupling), wherein a first measurement signal is detected during a movement of the drive shaft, and the first measurement signal or a derivative of the first measurement signal is evaluated with respect to a step-like change in order to detect a rotational backlash.

Abstract: A method is detect inadequate valve seat integrity in a control element of a control valve is proposed, wherein during a calibration time interval the position of the control element of the control valve in the closed position are repeatedly measured and recorded. Measuring of the position in the closed position continues during operation, and a moving average value is determined over a specified number of values. A threshold is determined from the calibration data set and the specified number. If the moving average deviates from the average of the calibration data by more than this threshold, a message is output. In particular, no additional sensors or scanning devices are required and a sensible compromise between early fault detection and avoidance of false diagnoses is achieved.

Abstract: In a closed loop control method for an electropneumatic field device, an electronic target value input of a command variable corresponding to a target value of a control center is received by the open loop and/or closed loop control electronics, an electronic output for a manipulating variable to pilot the electropneumatic converter is generated by the open loop and/or closed loop control electronics; and, in a predetermined operating condition of the field device, the manipulating variable is determined by a closed loop control algorithm based on the command variable and on another controlled variable different from an actual control member position measurement value.

Abstract: A method is detect inadequate valve seat integrity in a control element of a control valve is proposed, wherein during a calibration time interval the position of the control element of the control valve in the closed position are repeatedly measured and recorded. Measuring of the position in the closed position continues during operation, and a moving average value is determined over a specified number of values. A threshold is determined from the calibration data set and the specified number. If the moving average deviates from the average of the calibration data by more than this threshold, a message is output. In particular, no additional sensors or scanning devices are required and a sensible compromise between early fault detection and avoidance of false diagnoses is achieved.

Abstract: For determining the operability of a fluid driven safety valve, a method comprising the following steps is described: A partial stroke test is performed on the safety valve, resulting in a stroke-pressure curve. The stroke pressure curve is extrapolated (330, 340) beyond the measured range (360) up to the safety closing position (350). From the extrapolated stroke-pressure curve, the closing pressure reserve (320) can be determined. In this way, the functionality of the safety valve can be checked during operation.

Abstract: In a diagnostic method for a positioning device of a process plant, such as a chemical plant, a food processing plant or the like, which includes an actuator (e.g. pneumatic or electric actuator) with a drive shaft and a positioning armature, such as an actuator valve, with a positioning shaft, the drive shaft and the positioning shaft being connected to one another in a rotationally fixed manner (e.g. by a detachable coupling interface and/or a positive-locking torque coupling, such as a claw coupling), a first measurement signal is detected during a movement of the drive shaft, and the first measurement signal or a derivative of the first measurement signal is evaluated with respect to a step-like change in order to detect a rotational backlash.

Abstract: In a closed loop control method for an electropneumatic field device, an electronic target value input of a command variable corresponding to a target value of a control center is received by the open loop and/or closed loop control electronics, an electronic output for a manipulating variable to pilot the electropneumatic converter is generated by the open loop and/or closed loop control electronics; and, in a predetermined operating condition of the field device, the manipulating variable is determined by a closed loop control algorithm based on the command variable and on another controlled variable different from an actual control member position measurement value.

Abstract: The position controller for a pneumatic field device comprises a current-pressure transducer system having at least two I/P-transducers creating separate pneumatic control signals. Microelectronics creates at least two electrical control signals for the I/P-transducers. A pneumatic signal switching valve has at least two pneumatic inputs for the at least two pneumatic control signals, a pneumatic output for transferring a pneumatic control signal to a working chamber of the pneumatic field device and an electrical switch signal input. The pneumatic signal switch valve comprises a first switch position which blocks a first of the at least two pneumatic control signals and a second switch position which blocks a second of the pneumatic control signals.

Abstract: The position controller for a pneumatic field device comprises a current-pressure transducer system having at least two I/P-transducers creating separate pneumatic control signals. Microelectronics creates at least two electrical control signals for the I/P-transducers. A pneumatic signal switching valve has at least two pneumatic inputs for the at least two pneumatic control signals, a pneumatic output for transferring a pneumatic control signal to a working chamber of the pneumatic field device and an electrical switch signal input. The pneumatic signal switch valve comprises a first switch position which blocks a first of the at least two pneumatic control signals and a second switch position which blocks a second of the pneumatic control signals.