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.

A failure detection apparatus for a hydraulic system, to a hydraulic, failure detection-capable system, and to a method of operating a failure detection apparatus. The failure detection apparatus comprises a monitoring and failure detection unit that receives first and second pressure values from first and second pressure sensors and comprises a failure detection unit that detects a failure of at least one hydraulically operated device when a 2-tuple of a plurality of 2-tuples is within a first and outside a second predetermined tolerance range of relative pressure values, and wherein the failure detection unit 260 detects a failure of the pump when a 2-tuple of the plurality of 2-tuples is outside the first predetermined tolerance range of relative pressure values.

A system and method for detecting the location of coil open and coil short faults. The method includes obtaining an instantaneous admittance signature of each solenoid coil, sending out a periodic test signal to each valve, obtaining a new admittance signature; and calculating the coil-open and coil-short faults.

A device and method for diagnosing and configuring a hydraulic device based on a wireless local area network relates to diagnosis and configuration device technologies. The device includes a communication unit and mobile terminal. The communication unit reads hydraulic device data or changes device configuration, and process the data to generate webpage results. The mobile terminal transmits configuration requests, receives webpage results, and displays results in webpage form. The webpage results are formed by processing the acquired hydraulic device data at the communication unit side. The mobile terminal can complete the hydraulic device diagnosis and configuration, as long as it connects to the communication unit via WIFI and supports state of the art web content. The mobile terminal does not need additional installation of a matching diagnostic or configuration program, and is not limited as a specific device installed with a specific operating system; a general-purpose device may be used.

A fluid leakage detection device includes: a rod seal provided in a cylinder head, a rod seal being configured to seal an annular gap between a piston rod and the cylinder head; a detection seal configured to seal an annular gap, a detection seal being configured to partition the detection space together with the rod seal; a communication passage in communication with the detection space; a pressure sensor configured to detect the pressure of the working oil guided through the communication passage; and a relief valve configured to release the pressure in the communication passage, wherein the detection seal is provided between the rod seal and a dust seal, the dust seal being configured to seal the annular gap by being provided in the cylinder head so as to face the outside of the cylinder tube.

A stick slip detection system includes: an operation data storage unit configured to store a stick slip index, the stick slip index being a ratio of a first state amount based on a displacement of a valve shaft of a valve to be diagnosed to a second state amount based on the displacement; an abnormality diagnosis unit configured to determine whether a stick slip phenomenon occurs in the diagnosis target based on the stick slip index; and a diagnosis operation control unit configured to, when a stepwise change in a control command value in an intermediate opening degree of the valve to be diagnosed is detected, stop a determination operation of the abnormality diagnosis unit. The present disclosure makes it possible to easily reflect knowledge of an expert with respect to a diagnosis target such as a valve in the stick slip detection system and method.

An actuator system includes a piston-cylinder arrangement including a piston that is movable with respect to a cylinder. A first flow path is in fluid communication with the piston-cylinder arrangement and a second flow path is in fluid communication with the piston-cylinder arrangement. A control system is operable to fluidly connect the first flow path to a source of high-pressure fluid and to connect the second flow path to a drain to move the piston in a first direction. A pressure sensor is fluidly connected to the first flow path and is operable to measure sufficient pressure data during the movement of the piston to generate a pressure versus time curve. The control system is operable to compare the generated pressure versus time curve to a known standard pressure versus time curve stored in the control system to determine the condition of the piston-cylinder arrangement.

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.

A hydraulic leak detection system includes a leak detection switch responsive to a level of hydraulic fluid in a tank used by a hydraulic mowing circuit and a lift and lower circuit of a grass mowing machine. The system includes a controller that activates a warning indicator if the leak detection switch indicates the level of hydraulic fluid in the tank is low, but allows the hydraulic mowing circuit and the lift and lower circuit to continue operating until the lift and lower circuit reaches a fully raised position. A solenoid valve may control the level of hydraulic fluid in the tank based on temperature of the hydraulic fluid.

An actuator system includes a piston-cylinder arrangement including a piston that is movable with respect to a cylinder. A first flow path is in fluid communication with the piston-cylinder arrangement and a second flow path is in fluid communication with the piston-cylinder arrangement. A control system is operable to fluidly connect the first flow path to a source of high-pressure fluid and to connect the second flow path to a drain to move the piston in a first direction. A pressure sensor is fluidly connected to the first flow path and is operable to measure sufficient pressure data during the movement of the piston to generate a pressure versus time curve. The control system is operable to compare the generated pressure versus time curve to a known standard pressure versus time curve stored in the control system to determine the condition of the piston-cylinder arrangement.