Example methods and apparatus for independently controlling the seating force in a rotary valve are described herein. An example apparatus includes a rotary valve having a flow control member and a dual-acting actuator operatively coupled to the rotary valve. The actuator has first and second ports to receive a pressurized control fluid to change a position of the actuator. The example apparatus further includes a valve controller operatively coupled to the actuator to control the pressurized control fluid in response to a position of the rotary valve. The example apparatus further includes a pressure limiter operatively coupled to the valve controller and fluidly coupled to the first port of the actuator. The pressure limiter is to reduce a pressure of the pressurized fluid provided to the first port of the actuator to reduce a seating force of the flow control member when the rotary valve is in a closed position.

The invention relates to a valve unit for the exclusive hydraulic actuation of the locking means of a mechanical quick-changer for attachments of a construction machine, wherein the valve unit comprises a feed pressure connector for applying the feed pressure, a first valve unit outlet for connecting an unlocking pressure line, a second valve unit outlet for connecting a locking pressure line, at least one discharge to the tank, and at least two switchable directional valves, with the feed pressure connector being connected or connectable to the second valve unit outlet via a serial connection of the at least two switchable directional valves.

A valve, in particular having the form of a 2/2-way seat valve includes a pressure limiting function (28) integrated in a joint valve body to implement a thermal overpressure protection.

A regulator valve has a check valve manifold for use in subsea control circuits. For example, the regulator valve having the check valve manifold can be used in a circuit between a directional control valve and an actuator for a gate valve. The check valve manifold can have a flange that attaches to the regulator valve to communicate with the supply-side and outlet-side of the regulator valve. Internal communication inside the manifold includes a check valve. If the pressure in the circuit downstream of the regulator valve needs to be vented, the check valve can open to allow the pressure to bleed from the outlet-side back to the supply-side without needing to pass through the internal pressure control valve of the regulator.

A method of controlling a plurality of downhole tools in a wellbore, using first and second codes transmitted by hydraulic line to first address and then actuate the desired tool. A dedicated line is provided for terminating all actuated tools.

An actuated valve system includes a valve including a flow controlling valve element, an actuator assembled with the valve and including an inlet port in fluid communication with a fluid driven actuator member operatively connected with the valve element and movable from a normal position to an actuated position in response to pressurization of the inlet port to at least a minimum actuating pressure, a pilot valve operable to supply pressurized fluid to the actuator inlet port in a first position and to exhaust pressurized fluid from the actuator inlet port through an exhaust port in the pilot valve in a second position, and a backpressure arrangement in fluid communication with the actuator inlet port to retain a positive pressure smaller than the minimum actuating pressure against the actuator member when the pilot valve is moved to the second position.

An actuated valve system includes a valve including a flow controlling valve element, an actuator assembled with the valve and including an inlet port in fluid communication with a fluid driven actuator member operatively connected with the valve element and movable from a normal position to an actuated position in response to pressurization of the inlet port to at least a minimum actuating pressure, a pilot valve operable to supply pressurized fluid to the actuator inlet port in a first position and to exhaust pressurized fluid from the actuator inlet port through an exhaust port in the pilot valve in a second position, and a backpressure arrangement in fluid communication with the actuator inlet port to retain a positive pressure smaller than the minimum actuating pressure against the actuator member when the pilot valve is moved to the second position.