The movement process of electric valve device can be controlled by the stroke, torque or axial thrust. It is an indispensable equipment to realize valve program control, automatic control and remote control. The operating characteristics and utilization rate of the electric valve device are determined by the working specifications of the valve type device and the position of the valve on the pipeline or equipment, which requires us to correctly select the electric valve device to prevent overload (the working torque is higher than the control torque). The following is a brief introduction to the basis for correct selection of electric valve devices, as well as some main parameters of electric valve devices.

1. Operating torque: the output torque of the electric device shall be 1.2~1.5 times of the maximum operating torque of the valve. The main engine structure for operating the thrust electric valve device can be divided into two types: no thrust disc and thrust disc. The electric valve device without thrust disc can output torque directly, while the electric valve device with thrust disc can output torque through the stem nut in the thrust disc< br /> 2. Number of rotation turns of output shaft: the number of rotation turns of the output shaft of the electric valve device is related to the nominal diameter of the valve, the screw pitch of the valve stem, and the number of screw heads, which should be calculated as M ＝ H/ZS (M is the total number of rotation turns that the electric device should meet, H is the valve opening height, S is the screw pitch of the valve stem drive thread, and Z is the number of screw heads of the valve stem)< br /> 3. The influence of stem diameter on multi turn rising stem valves shall be considered. If the maximum valve stem diameter allowed by the electric device cannot pass through the valve stem of the matched valve, the electric valve cannot be assembled. 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 non rising stem valves in partial turn valves and multi turn valves, although the passage of the valve stem diameter is not considered, the valve stem diameter and the size of the keyway should also be fully considered when selecting, so that they can work normally after assembly.

4. Opening and closing speed: if the opening and closing speed of the output speed valve is too fast, water hammer is likely to occur. At this time, appropriate opening and closing speed should be selected according to different use conditions.