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When selecting a valve electric actuator, the following points should be taken into account: 1. Operating torque: Operating torque is the most important parameter for choosing a valve electric actuator; the torque output by the actuator should be 1.2 to 1.5 times the maximum torque required to operate the valve. 2. There are two types of main structures for the motor units that operate thrust valves: one type does not include a thrust disc and directly generates torque ； Another approach is to use a thrust disc, with the output torque being converted into output thrust through the valve stem nut in the thrust disc. 3. Number of rotations of the output shaft: The number of rotations of the output shaft of the valve actuator is related to the nominal diameter of the valve, the pitch of the valve stem thread, and the number of thread turns. It should be calculated using the formula M = H/ZS (where M represents the total number of rotations required by the actuator, H is the opening height of the valve, S is the pitch of the valve stem drive thread, and Z is the number of thread turns on the valve stem). 4. For multi-turn straight-stem valves, if the maximum valve stem diameter allowed by the electric actuator is larger than that of the valve’s stem, it is not possible to assemble an electric valve. Therefore, the inner diameter of the hollow output shaft of the electric actuator must be larger than the outer diameter of the valve stem of the straight-stem valve. For some rotary valves and stemless valves among multi-rotary valves, although there is no need to consider the issue of the valve stem diameter fitting through, the dimensions of the valve stem diameter and the keyway should still be taken into full consideration during selection to ensure proper operation after assembly. 5. Output speed: If the opening and closing speed of the valve is too fast, water hammer phenomenon is likely to occur. Therefore, the appropriate opening and closing speed should be selected based on different operating conditions. 6. Valve electric actuators have specific requirements, namely the ability to limit torque or axial force. Typically, valve actuators use couplings that limit torque. Once the specifications of the electric drive are determined, its control torque is also determined. It generally operates within a predetermined time frame, so the motor will not be overloaded. 7. Control type: Valve electric actuators are divided into on-off type and control type; the signals for control-type actuators are further categorized into current signals and voltage signals. 8. Control voltage: The voltages for conventional electric actuators include AC220V, AC380V, DC24V, etc.