Cowan Connection

Electro-hydraulic actuators are devices that operate a valve through pressurized hydraulic fluid, however, their main source of energy is solely electrical. The electrical power supplied is used to energise a motor that runs a hydraulic pump which then supplies the pressurized fluid to operate a hydraulic actuator which controls the valve. The complete system is self-contained, eliminating the need for a separate hydraulic power unit, simplifying system construction and improving safety and reliability. A self-contained electrohydraulic actuator can be used with linear or rotary valves, the need for its use will depend on the requirements of the application. These devices are ideal for operating valves that need large torques or thrusts, or where fail-safe systems or high operating...

Due to their design, electric actuators have limitations in terms of output torques, duty cycle, failure modes, speeds, and vibration resistance.   In severe applications where valves with high torque or thrust must be operated quickly, such as emergency shutdown valves (ESDV), electric actuators have limitations because they can only store a certain amount of energy to operate the valve in the event of a power failure, which eliminates them as options in many emergency shutdown valve applications. In the same way, because they are operated directly by an electric motor, they present limitations in the operating speed; on one hand, the demand increases significantly as the speed increases and on the other hand, their operating speeds are constant since they depend on the RPMs of the...

Flotation cells are mechanical equipment that bring the ore in contact with air, water, and chemical agents. Their main function is to separate the previously conditioned slurry into a concentrate and tailings. The level of these cells is controlled by dart valves, which in turn are operated by actuators. The calculation of the level control valve (Dart) in flotation cells requires high consideration as the goal is accurate flow control to maximize slurry retention time and minimize downtime, therefore a reliable and accurate control valve actuator is essential. Traditionally dart valves use mechanical connections to feed position feedback to positioners that are then used to operate the actuators. The mechanical connections or arms, because they are exposed, are easily jammed, loosened,...

Valves are used to control the flow of fluids in process control applications by opening, closing, or partially obstructing the fluid flow and controlling the line pressure. Depending on the flow requirements of the process system, some method of changing the positions of valves is needed. Some valves are operated with hand wheels or levers. Other valves must be open, closed or throttled frequently. Manually positioning valves in these types of situations is not practical and instead of using hand wheels or levers to control actuation, automated valve solutions such as valve actuators are used to position the valves. What is a valve actuator? A valve actuator is defined as a mechanical device that moves or controls a device such as a control valve. Actuators reduce the need for operators...