The valve electric device is one of the devices for operating the valve and connecting the valves. The device is powered by electrical power and its motion can be controlled by the magnitude of the stroke, torque or axial thrust. Due to the working characteristics and utilization of the valve electric device, it depends on the type of valve, the working specifications of the device and the position of the valve on the pipeline or equipment. Therefore, it is important to grasp the correct choice of the valve electric device; considering the prevention of overload (working torque is higher than the control torque) becomes a crucial part.
The correct choice of valve electric device should be based on:
1. Operating torque: Operating torque is the most important parameter for selecting the valve's electric device. The output torque of the electric device should be 1.2 to 1.5 times the maximum torque of the valve operation.
2. Operation thrust: There are two kinds of main structure of the valve electric device. One is that the thrust plate is not arranged, and the torque is directly output. The other is the configuration with the thrust plate. At this time, the output torque passes through the stem nut in the thrust plate. Converted to output thrust.
3. Number of rotations of the 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 threads. It is calculated according to M=H/ZS (where: M is the electric device should be satisfied) The total number of revolutions; H is the opening height of the valve, mm; S is the pitch of the stem drive thread, mm; Z is the number of stem threads.)
4. Stem diameter: For multi-turn type open-end valves, if the maximum stem diameter allowed by the electric device cannot pass through the valve stem of the valve, it cannot be assembled into an electric valve. Therefore, the inner diameter of the hollow shaft of the electric device must be larger than the outer diameter of the stem of the open rod valve. For the partial rotary valve and the dark rod valve in the multi-turn valve, although the problem of the diameter of the stem is not considered, the diameter of the stem and the size of the keyway should be fully considered in the selection, so that the assembly can work normally.
5. Output speed: The opening and closing speed of the valve is fast, which is easy to produce water hammer. Therefore, the appropriate opening and closing speed should be selected according to different conditions of use.
6. Installation and connection method: The installation method of the electric device is vertical installation, horizontal installation and floor installation; the connection mode is: thrust plate; the valve stem passes (bright multi-turn valve); the dark rod rotates more; no thrust plate; the valve stem does not Through; the rotary electric device has a wide range of uses, and is an indispensable device for realizing valve program control, automatic control and remote control, and is mainly used on closed-circuit valves. However, the special requirements of the valve electric device cannot be ignored - the torque or axial force must be limited. Usually the valve electric device uses a torque limiting coupling.