Provided are: a valve control device which is capable of reducing the difference between a set opening amount and the actual opening amount, when executing a partial valve stroke test; a valve control system; a method for calculating a valve control coefficient; and a valve control method. This shut-off valve control device is provided with a microcomputer for controlling the opening and closing of a solenoid valve which supplies air from an air supply source, to a cylinder of an air cylinder for controlling a valve shaft of a shut-off valve, and discharges said air. The microcomputer acquires a set opening amount of the shut-off valve. Furthermore, the microcomputer controls the solenoid valve to a value obtained by dividing the acquired set opening amount by a predetermined coefficient C.

An arrangement includes a field device with an on/off valve, a pneumatic actuator that moves the on/off valve, when applied with compressed air, into one on/off position and when ventilated into the other on/off position, a magnetic valve that applies compressed air to the actuator during electric actuation and ventilates the actuator during non-actuation and a function monitoring device that detects at least one parameter that refers to the movement of the on/off valve, where the function monitoring device includes a magnetic field sensor detecting changes to a magnetic field, where the magnetic field sensor is arranged in the region of the magnetic valve and generates a signal awakening the function monitoring device to detect the at least one parameter.

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.

A pneumatically controlled flow booster includes a booster valve plug position sensor that enables control of the flow booster in a feedback loop, for example by a pneumatic valve positioner, thereby providing accurate, high speed, high flow control of both small and large actuator adjustments. Embodiments can accurately control a surge suppression valve over extended valve adjustment ranges and can fully open a surge suppression valve during a trip. The flow booster valve can include a spool and sleeve valve and/or a poppet valve. Embodiments provide bimodal flow boosting, whereby the output flow is less dependent on the valve plug position in a first position range, and more strongly dependent on the valve plug position in a second range.

A control device for at least one hydraulic working section (A, B), which can be connected to a pressure supply source (P) and a return flow (T) via a hydraulic supply circuit and to a control valve (34) supplied with a pilot pressure. The device includes an emergency shutdown system (32) having a pilot solenoid valve (16) and an additional valve (14). Both the hydraulic energy flow from the pressure supply source (P) to at least one of the respective working sections (A, B) and the pilot pressure supply to the control valve (34) can be suppressed by the pilot solenoid valve (16) via the additional valve (14).

An apparatus for controlling a hydraulic machine, for example a turbine, pump or pump turbine, using variable-speed driven fixed displacement pumps. The apparatus includes a device for carrying out an emergency shut-off that is characterized by low energy consumption and high efficiency while guaranteeing all the operation-relevant and safety-relevant requirements of a hydraulic machine.

An arrangement includes a field device with an on/off valve, a pneumatic actuator that moves the on/off valve, when applied with compressed air, into one on/off position and when ventilated into the other on/off position, a magnetic valve that applies compressed air to the actuator during electric actuation and ventilates the actuator during non-actuation and a function monitoring device that detects at least one parameter that refers to the movement of the on/off valve, where the function monitoring device includes a magnetic field sensor detecting changes to a magnetic field, where the magnetic field sensor is arranged in the region of the magnetic valve and generates a signal awakening the function monitoring device to detect the at least one parameter.

A bootstrap hydraulic reservoir includes a bootstrap chamber to hold hydraulic fluid, a piston chamber fluidly connected to a pressure line of the hydraulic fluid system, a piston having a bootstrap end portion held within the bootstrap chamber and a pressure end portion held within the piston chamber, and a hydraulic accumulator fluidly connected to the pressure line of the hydraulic fluid system. The hydraulic accumulator accumulates pressurized hydraulic fluid from the pressure line. The bootstrap hydraulic reservoir also includes a valve fluidly connected to the pressure line of the hydraulic fluid system between the hydraulic accumulator and an outlet of a pump of the hydraulic fluid system. The valve includes an actuator selectively moves the valve to an open position when the pressure line of the hydraulic fluid system is de-pressurized.

Methods, apparatus, systems and articles of manufacture are disclosed to diagnose a pneumatic actuator-regulating accessor. An example method disclosed herein includes stroking a fluid valve operatively coupled to a field instrument and a pneumatic actuator-regulating accessory by pressurizing an actuator operatively coupled to the fluid valve. The example method also includes blocking a supply to the pneumatic actuator-regulating accessory and the field instrument, exhausting pressurized air from the actuator via the field instrument, measuring at least one of (1) positions of the fluid valve or (2) an output pressure as the pressurized air is exhausted from the actuator, and identifying a first operation of the pneumatic actuator-regulating accessory based on at least one of a travel rate of the fluid valve or the output pressure, the travel rate of the fluid valve based on the measured positions of the fluid valve.

A hydraulic apparatus includes a first valve manifold that provides a shutdown capability and a second valve manifold that provides an overspeed control capability. The hydraulic apparatus advantageously further employs a hydraulic appliance that includes a check valve and a bypass apparatus. The hydraulic appliance enables the second valve manifold to additionally provide as an alternative function a redundant shutdown capability, thereby obviating the need to have three separate valve manifolds.