Classification and selection of valve electric actuators

Time:

2023-08-23

Source:

network

Author:

　　1、 Classification of valve electric actuators

　　Valve electric actuators can be divided into three types based on the movement mode of the output shaft.

　　1. Partial rotary electric actuator

　　The rotation of the output shaft of a partially rotating electric actuator is less than one turn, with a rotation angle of less than 360 degrees. A 90 degree rotation of the output shaft can achieve the opening and closing process of the valve. Partial rotary electric actuators are used in conjunction with butterfly valves, ball valves, and plug valves.

　　2. Multi turn electric actuator

　　The output shaft of a multi turn electric actuator rotates more than 360 degrees and generally requires multiple turns to achieve the opening and closing action of the valve. Multi turn electric actuators are mainly used in conjunction with gate valves and globe valves.

　　3. Straight stroke electric actuator

　　The motion trajectory of the output shaft of a straight stroke electric actuator is linear motion, not rotational motion.

　　2、 Selection of valve electric actuators

　　Usually, the correct basis for selecting a valve electric actuator is as follows: v 1. Operating torque: Operating torque is the main parameter for selecting a valve electric device, and the output torque of the electric actuator should be 1.2-1.5 times the maximum operating torque of the valve.

　　There are two main structures for operating the electric device of the thrust valve: one is to output torque directly without configuring the thrust disc; Another approach is to configure a thrust disc, where the output torque is converted into output thrust through the valve stem nut in the thrust disc.

　　3. Number of output shaft rotations: The number of output shaft rotations of the valve electric device is related to the nominal diameter, valve stem pitch, and number of thread heads of the valve, and should be calculated according to M=H/ZS (M is the total number of rotations that the electric device should meet, H is the valve opening height, S is the valve stem transmission thread pitch, and Z is the number of valve stem thread heads).

　　4. For multi turn open stem valves, if the larger valve stem diameter allowed by the electric device cannot pass through the valve stem of the matched valve, it cannot be assembled into an electric valve. Therefore, the inner diameter of the hollow output shaft of the electric device must be greater than the outer diameter of the stem of the rising stem valve. For partially rotating valves and non rising stem valves in multi rotating valves, although the diameter of the valve stem does not need to be considered when selecting, the size of the valve stem diameter and keyway should also be fully considered to ensure normal operation after assembly.

　　5. Output speed: If the opening and closing speed of the valve is too fast, it is prone to water hammer phenomenon. Therefore, the appropriate opening and closing speed should be selected according to different usage conditions.

　　6. Valve electric actuators have special requirements, that is, they must be able to limit torque or axial force. Usually, valve electric devices use torque limiting couplings. After the specifications of the electric device are determined, its control torque is also determined. Generally, it operates within a predetermined time and the motor will not overload.

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