Butterfly valve selection rules

- Aug 03, 2018-

The selection rules are explained in the following aspects:

Stem Diameter: For multi-turn type open rod valves, it cannot be assembled into an electric valve. Therefore, if the maximum stem diameter that the electric butterfly valve device allows to pass cannot pass through the valve stem of the valve being fitted, the inner diameter of the hollow output shaft of the electric device must be larger than the outer diameter of the stem of the open 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 it can work normally after assembly.

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 stroke, torque or axial thrust. Since the working characteristics and utilization rate of the valve electric device depend on the type of valve, the working specification and the position of the valve on the pipeline or equipment, the valve electric butterfly valve device is an indispensable device for realizing valve program control, automatic control and remote control. Therefore, the correct selection of the valve electric device is essential to prevent the occurrence of overload (operating torque is higher than the control torque). Usually, this is the basis for the correct selection of the valve electric butterfly valve device.

The output torque of the electric device should be 1.2-1.5 times the maximum torque of the valve operation.

Electric butterfly valve operation thrust: There are two kinds of main structure of the valve electric device: one is to configure the thrust disc, the output torque is converted into the output thrust through the stem nut in the thrust disc, and the torque is directly output; the other is that the thrust disc is not arranged.

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. To press M=HZS (H is the valve opening height, M is the total number of revolutions that the electric device should meet, S is the stem drive thread pitch, and Z is the number of stem threads).