Electrohydraulic valve actuators are used in on/off and emergency shutdown actuation applications to stop process flow upon detecting a command signal or loss of power, protecting personnel, equipment, and the environment. The Bettis EHO Electro-Hydraulic Operator is a self-contained electro-hydraulic actuator designed to actuate quarter-turn valves, including ball, butterfly, plug, and triple-offset valves. It is designed to provide fail-safe actuation for emergency shutdown (ESD) valves.

This quick, two-minute YouTube video, Local Operation of a Bettis EHO Actuator, shows how to manually open and close a Bettis EHO actuator while the unit is in local mode. Using time-proven, final control innovation combined with the best in critical shutdown and process shutdown reliability, the Bettis Standard EHO for on/off applications and Smart EHO for modulating applications are effective options for maintaining and operating shutdown valves in severe, inaccessible, and remote locations.

Visit the Actuators section on Emerson.com for more information on these and other valve actuation solutions.

Transcript

Welcome. This video demonstrates the local operation of a Bettis EHO actuator with a backup accumulator.

Opening

To open the actuator locally, first put the unit in local mode. Then use the left-hand control knob to provide an open command. After receiving the open command, the actuator will flow high-pressure hydraulic fluid from a charged accumulator through the manifold.

After passing through the manifold, the fluid flows through an adjustable flow control, which adjusts the speed of operation. The fluid continues into the hydraulic cylinder causing the actuator to open.

As the actuator opens, low-pressure fluid stored in the other side of the actuator’s hydraulic cylinder is returned to the reservoir. The return fluid is used to recharge the backup accumulator between operations. When the actuator is in either the local or remote mode, the backup accumulator will automatically recharge when the EHO senses a pressure below its setpoint.

To charge the backup accumulator, the electric motor drives a gear pump. The fluid flows from the pump to the manifold, which blocks flow to the actuator and redirects the fluid to the backup accumulator. As the backup accumulator fills and pressurizes, the EHO senses the pressure in the system to shut off the motor when it’s filled.

Closing

With the unit in local mode, use the left-hand control knob to provide a close command. The closing solenoid will actuate and allow the high-pressure fluid that is holding the spring in compression to be able to return through the manifold flow control to the reservoir.

-End of transcript-

The post Local Control for Electrohydraulic Valve Actuators appeared first on the Emerson Automation Experts blog.

Local Control for Electrohydraulic Valve Actuators

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