One of the most important issues when selecting a high-torque electric actuator is torque matching. If the output torque is insufficient, the actuator may not reliably drive the valve. On the other hand, selecting an unnecessarily large actuator without considering the actual operating conditions can make the overall configuration more complicated. USA VTON therefore focuses on the actual valve operating requirements during high-torque electric actuator selection.
1. What Is the Output Torque of an Electric Actuator?
The output torque of an electric actuator can be understood as the rotational driving force transmitted from the actuator output shaft to the valve.
During valve opening and closing, the actuator needs to overcome sealing friction, medium pressure, and resistance generated by the mechanical structure of the valve.
Therefore, a valve’s DN200 or DN500 size alone cannot determine the required actuator torque.
The more useful information is the opening and closing torque provided by the valve manufacturer or confirmed through actual operating-condition analysis.
2. Three Main Factors in Torque Matching
1. Valve Operating Torque
Different valve structures require different torque levels.
For example, butterfly valves are affected by the disc, sealing structure, and medium pressure, while ball valves require consideration of friction between the ball and sealing components.
Therefore, the actuator should not be selected independently from the valve.
2. Medium Pressure and Temperature
Medium pressure can affect the forces acting on a valve during operation, while temperature may influence the working condition of sealing materials and related components.
For high-temperature or high-pressure applications, USA VTON selection should include these parameters in the torque-matching process.
3. Operating Frequency and Working Mode
A valve that operates only a few times per day has different actuator requirements from a valve that operates frequently in an automated process.
The actuator type should also be confirmed as on-off or modulating, together with the required opening and closing time.
3. Why Should a Torque Margin Be Considered?
An actuator should not normally be selected based only on the theoretical minimum torque.
Actual field operation can be affected by sealing friction, medium conditions, temperature changes, and mechanical conditions. A reasonable torque margin should therefore be considered according to the engineering requirements.
However, the torque margin should not be increased without limit. It should remain consistent with the actual valve requirements and actuator technical specifications.
4. Industrial Valve Automation Application at a Certain Location
At a certain location, an industrial installation required remote control of multiple large-diameter valves. Some valves operated under relatively high pressure and required electric actuators for reliable opening and closing.
For this type of application, USA VTON can organize the valve type, diameter, pressure, temperature, and actual operating torque for each valve before matching actuator output torque, power supply, and control method.
Evaluating each valve individually instead of assigning one actuator specification to every valve is a more practical engineering approach.
5. How Should the Basic Torque Relationship Be Understood?
From a basic mechanical perspective, torque is related to force and lever arm:
For actual valve actuator selection, however, a simple mechanical relationship should not be used as the only basis. The valve’s actual operating torque and the actuator’s technical specifications should be considered together.
Conclusion
The purpose of high-torque electric actuator selection is not simply to pursue a larger torque value. The objective is to match the valve’s actual requirements, actuator output capability, and field operating conditions.
For selection, provide valve type, diameter, pressure, temperature, operating torque, power supply, and control method first. USA VTON can then evaluate the actuator configuration according to the actual conditions.
