This paper introduces the classification and selection of electric actuators in detail. Part of the valve knowledge data is taken from the VTON valve literature in Witton, USA. After original editing, if you think the answer is helpful to you, please kindly praise the American Witton VTON valve.
Valve electric actuator is a special driving device used to drive the valve to open and close, which consists of special motor, worm gear, stroke and torque detection mechanism and control part. Different industries and working conditions have different requirements for valve electric drive devices.
Valve electric drive devices are generally classified according to structure type, working mode, rotating mode and working environment.
1, which can be divided into two types according to the structure type: integrated type and split type. Integrated valve electric device can be divided into ordinary type and intelligent type. The split valve electric device is that all the control devices that control the operation of the valve electric device are installed in a single electrical control cabinet. The electric actuator may provide an electric drive for that separation valve. The device has large starting torque and accurate valve stroke control, and is widely used in valves in petroleum, chemical, hydropower, metallurgy, shipbuilding, light industry, food and other industries. The integrated valve electric device is to install all the control devices that control the operation of the valve electric device inside the valve electric device and integrate it with the valve electric device. Integrated valve electric device can be divided into ordinary type and intelligent type.
2. According to the rotation mode, it is divided into angular stroke, straight stroke and multi-rotation; Imported electric butterfly valve, imported electric ball valve angular stroke electric actuator, imported electric globe valve multi-turn electric actuator.
3, according to the working environment is divided into waterproof, explosion-proof; For example, electric actuators with protection grades of IP65, IP67 and IP68, explosion-proof grade? Electric actuators for ExdIIBT4, ExdIIBT6 and ExdIICT5
The correct selection of imported valve electric actuator should be based on:
1. Operating torque: Operating torque is the most important parameter for selecting valve electric device. The output torque of the electric device shall be 1.2 ~ 1.5 times of the maximum operating torque of the valve.
2. Working thrust: There are two main structures of the valve electric device, one is that the thrust plate is not installed, and the torque is directly output at this time; The other is equipped with a thrust disc, at which time the output torque is converted into output thrust through the valve stem nut in the thrust disc.
3. Output shaft revolution: The revolution 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, and is calculated as M=H/ZS (where m is the total revolution that the electric device should meet; H is the opening height of the valve, mm; S is the pitch of the valve stem transmission thread, mm; Z is the number of threaded heads of the valve stem. )
4. Stem diameter: For a multi-turn open stem valve, if the maximum stem diameter allowed by the electric device cannot pass through the valve stem, 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 exposed stem valve. For some rotary valves and hidden stem valves in multi-rotary valves, it is not necessary to pass the valve stem diameter, but the valve stem diameter and keyway size should be fully considered in the selection to make them work normally after assembly.
5. Output speed: the valve is fast in opening and closing speed, and it is easy to produce water hammer. Therefore, the appropriate opening and closing speed should be selected according to different use conditions.
6. Installation and connection methods: The installation methods of electrical devices include vertical installation, horizontal installation and floor installation; Connection mode: thrust plate; The valve stem passes through (open-stem multi-rotary valve); Multiple rotations of hidden rods; Thrust-free disk; The valve stem does not pass; Partial rotary electric device is widely used, and it is an indispensable equipment to realize program control, automatic control and remote control of valves. It is mainly used for closed-circuit valves. But we can't ignore the special requirements of valve electric device-it must be able to limit torque or axial force. Usually, the valve electric device uses a coupling that limits torque.