Selection Rules And Installation Maintenance of Butterfly Valves

Selection rules of butterfly valves
Stem diameter of butterfly valves: It is for multi turn rising stem valve. It cannot be assembled into an electric valve. Therefore, the the max stem diameter of butterfly valves allowed by the electric butterfly valve device cannot pass through the valve stem of the matched valve. The inner diameter of hollow output shaft of electric device must be larger than the outer diameter of stem of rising stem valves. For the non rising stem valves in local rotary valves and multi rotary valves, the diameter of the stem and the size of the keyway should be fully considered in the selection, so that they can work normally after assembly.

Operating torque: operating torque is the main parameter for selecting valve electric device. The movement process of electric butterfly valves can be controlled by stroke, torque or axial thrust. Since the working characteristics and utilization rate of valve electric device depend on the type of valves, the working specification of device and the position of valves on pipeline or equipment, the electric butterfly valve device is indispensable equipment to realize program control, automatic control and remote control of valves. Therefore, the correct selection of valve electric device is very important to prevent overload phenomenon (the working torque is higher than the control torque). Generally, the basis for the correct selection of electric butterfly valve device.

The output torque of the electric device shall be 1.2-1.5 times of that of the largest valve operation.

There are two types of butterfly valve structures: Electric thrust device. The output torque is converted into output thrust through the stem nut in the thrust disc. Direct torque output. The other is the configuration of thrust disk.

Rotation number of output shaft: the number of rotation turns of output shaft of valve electric device is related to the nominal diameter of valves. The pitch of valve stem and the number of thread heads. H is the opening height of the valves, which shall be calculated as M = HZS (M is the total number of rotations that the electric device shall meet. S is the screw pitch of the valve rod drive thread, and Z is the number of valve rod thread heads.

Installation and maintenance of butterfly valves
1. During installation, the valve disc should stop at the closed position.
2. The opening position shall be determined according to the rotation angle of butterfly plates.
3. For butterfly valves with bypass valves, the bypass valves should be opened before opening.
4. The installation shall be carried out according to the manufacturer's installation instructions, and the heavy butterfly valves shall be provided with a firm foundation.