The selection rules are described in the following ways:
Stem diameter: For many rotary type of valve, can not be assembled into electric valves. Therefore, if the maximum stem diameter permitted by the electric butterfly valve device is not passed through the valve stem of the valve, the inner diameter of the hollow output shaft of the electric device must be greater than the stem diameter of the valve of the valve. For the local rotary valve and multiple rotary valve in the dark stem valve, although not to consider the valve stem diameter through the problem, but in the selection should also take full account of the diameter of the stem and the size of the keyway, so that the assembly can work properly.
Operating torque: Operating torque is the most important parameter for selecting the valve electric device. The motion of the electric butterfly valve can be controlled by the size of stroke, torque or axial thrust. Because the operating characteristics and utilization of the valve electric device depends on the type of valve, the working standard and the position of the valve in the pipeline or the equipment, the valve electric butterfly valve device is an indispensable equipment to realize the valve program control, self-control and remote control. Therefore, the correct choice of valve electric device, to prevent the occurrence of overload (work torque is higher than the control torque) is critical. Usually, this is the correct choice of valve electric butterfly valve device basis.
The output torque of the electric device shall be 1.2-1.5 times times the maximum torque of the valve operation.