Distinguishing Between Quarter-Turn and Multi-Turn Electric Actuators in Valve Operation

Difference Between Quarter-Turn Electric Actuators and Multi-Turn Electric Actuators

Quarter-Turn Electric Actuators

These actuators enable a valve to rotate 90 degrees, which is one-quarter of a full circle, hence the name. The mechanism inside a quarter-turn electric actuator typically employs a motor that drives gears to convert the motor's rotational movement into the 90-degree valve turn. These actuators are commonly found mounted on ball, plug, and butterfly valves.

A ball valve, for instance, has a ball with a hole in its center. When the actuator turns the ball to align the hole with the pipeline, it allows flow. Conversely, when it turns the ball so the hole sits perpendicular to the pipeline, it stops the flow. Similarly, a butterfly valve has a disc mounted on a rotating shaft. When the disc is parallel to the flow of liquid or gas, it lets the medium pass. Rotating it 90 degrees blocks the flow.

Multi-Turn Electric Actuators

As the name suggests, multi-turn electric actuators provide multiple rotations. These actuators often have mechanisms that allow the motor's continuous rotational motion to interface with valves requiring multiple turns to move from the open to closed positions or vice versa. Gate, globe, and some types of linear stem valves are ideal examples of where multi-turn actuators find their application.

For instance, consider a gate valve. It has a gate or wedge that moves up or down to obstruct or allow flow. This movement is not a simple rotation but requires multiple stem turns to ensure the gate fully ascends or descends. A multi-turn electric actuator provides this function. When the actuator motor rotates, it has a threaded stem that moves linearly, raising or lowering the valve's gate. A similar operation exists for globe valves, where the stem and the attached disc or plug move linearly up and down to regulate flow.

In summary, quarter-turn electric actuators serve valves that need a 90-degree rotation, such as ball, plug, and butterfly valves. In contrast, multi-turn electric actuators cater to those valves that demand multiple rotations, like gate and globe valves. The choice between the two depends heavily on the specific valve type and the desired control mechanism in the industrial setup.

UniTorq Actuators and Controls
2150 Boggs Road, Suite 410
Duluth, GA 30096
Phone: (770) 446-7074
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