The operation of an electric ball valve is based on the synergy between the electric actuator and the valve mechanism. Its working principle can be divided into the following steps:
1. Core Operation Process
Control Signal Input
The electric actuator receives an electrical signal from the control system (typically a 4-20mA current signal or a 0-10V voltage signal).
On-off ball valves receive on/off commands (fully open/close), while regulating ball valves receive continuous proportional signals (for precise opening control).
Power Transmission and Mechanical Drive
The motor in the actuator starts, reducing the speed and increasing the output torque via a reduction gear train.
The worm gear mechanism converts the motor's rotational motion into a 90° angular stroke of the valve stem.
2. Valve Opening and Closing and Regulation
The valve stem rotates the ball:
Open State: The ball's through-hole is aligned with the pipe axis, minimizing flow resistance (the full-bore design has a flow capacity close to the pipe).
Closed State: After the ball rotates 90°, the through-hole becomes perpendicular to the pipe, and the ball presses against the valve seat (PTFE or metal seal), creating a bidirectional shutoff. Regulating ball valves achieve linear flow adjustment by controlling the rotation angle (e.g., 15°, 45°) (V-shaped ball valves are particularly adept at throttling control).
Safety and Feedback Mechanisms
Limit Protection: Built-in limit switches automatically cut off motor power when the fully open/closed position is reached.
Torque Protection: The torque limiting mechanism slips during overload, preventing valve stem deformation or motor burnout.
Status Feedback: Some actuators output valve position signals (e.g., 4-20mA) for real-time monitoring by the control system.
Key Design Features
Fast Response: The 90° rotation mechanism reduces opening and closing times to less than 1 second, making it ideal for emergency shutoff scenarios.
Low Flow Resistance: The full-bore ball valve's flow path matches the pipe's inner diameter, resulting in negligible pressure drop.
Sealing Safety: Fireproof: The metal valve seat provides a secondary seal in the event of soft seal failure.
Anti-Static Design: A spring between the ball and stem dissipates frictional static electricity, eliminating the risk of explosion from flammable media.
3. Typical Operation Scenarios
Remote Opening and Closing: Remotely shut off pipeline media (e.g., emergency isolation in a chemical plant) via buttons in the control room or commands from the central control system.
Precise Flow Control: Modulating actuators open at a set ratio to stably control reactor feed flow (with an accuracy of ±1%).
Automatic Interlocking: Linked with sensors (e.g., automatically closing a valve when the liquid level exceeds a certain threshold), this creates a safety protection system.