More and more factories have adopted automatic control, and manual operation has been replaced by machinery or automation equipment. People require the actuator to play the role of the interface between the control system and the mechanical movement of the valve. They also require the actuator to enhance the work safety performance and environment. Protective performance. In some dangerous situations, the automatic actuator device can reduce the injury of personnel.
The main advantages of electric actuators are high stability and constant thrust that can be applied by the user. The maximum actuator can generate thrust of up to 225000kgf. Only hydraulic actuators can achieve such a large thrust, but the cost of hydraulic actuators is higher than electric actuators Much higher.
The anti-deviation ability of the electric actuator is very good. The output thrust or torque is basically constant. It can overcome the unbalanced force of the medium and achieve accurate control of the process parameters. Therefore, the control accuracy is better than that of the pneumatic actuator. high.
Pay attention to the following points when selecting the valve electric actuator correctly:
I. Operating torque: The operating torque is the most important parameter for selecting a valve electric actuator, that is, a valve electric actuator. The output torque of the electric actuator should be 1.2 to 1.5 times the maximum valve operating torque.
Second, there are two types of host structure for operating the thrust valve electric device: one is to directly output torque without a thrust disk; the other is to configure the thrust disk, and the output torque is converted to output thrust through the valve stem nut in the thrust disk.
3. Number of rotations of output shaft: The number of rotations of the output shaft of the valve electric device is related to the nominal diameter of the valve, the pitch of the valve stem, and the number of screw heads. It should be calculated according to M = H / ZS (M is the value that the electric device should meet Total number of rotations, H is the valve opening height, S is the thread pitch of the valve stem transmission thread, and Z is the number of thread heads of the valve stem).
4. Stem diameter For multi-turn open-stem valves, if the maximum stem diameter allowed by the electric device cannot pass through the stem of the valve, it cannot be assembled into an electric valve. Therefore, the inner diameter of the hollow output shaft of the electric device must be larger than the outer diameter of the stem of the bright stem valve. For the part of the rotary valve and the multi-turn valve of the dark-stem valve, although the passage of the stem diameter need not be taken into consideration, the diameter of the stem and the size of the keyway should be fully taken into consideration when matching, so that it can work normally after assembly.
V. Output speed: If the opening and closing speed of the valve is too fast, water hammer will easily occur. Therefore, the appropriate opening and closing speed should be selected according to different use conditions.
6. After the specifications are determined, the control torque is also determined. Generally run within a predetermined time, the motor will not be overloaded
Control mode: The valve electric actuator is divided into switch type and regulating type, and the signal of regulating type actuator is also divided into current signal and voltage information number.
Control voltage: The voltage of conventional electric actuators is AC220V, AC380V, DC24V, etc.
Overview of electric valves
The electric valve is simply to use an electric actuator to control the valve, so as to realize the opening and closing of the valve. It can be divided into two parts, the upper part is an electric actuator and the lower part is a valve. Electric valve should be simulated and pressure tested before installation.
The electric valve has a larger operating force distance than ordinary valves. The electric valve switching speed can be adjusted. The structure is simple and easy to maintain. It can be used to control air, water, steam, various corrosive media, mud, oil, liquid metals and radioactive media The flow of various types of fluids. However, due to the buffering characteristics of the gas itself, the traditional pneumatic valve is not easy to be damaged due to jamming, but it must have an air source, and its control system is more complicated than an electric valve. This type of valve should generally be installed horizontally in the pipeline.
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