1. The butterfly plate of the butterfly valve is installed in the diameter direction of the pipeline.
2. When installing the butterfly plate, it should be stopped in the closed position.
3. The opening position should be determined according to the rotation angle of the butterfly plate.
4. Butterfly valves with bypass valves should be opened before opening.
5. The installation should be carried out according to the installation instructions of the butterfly valve manufacturer. For heavy butterfly valves, a solid foundation should be set up.
Precautions for the use and maintenance of butterfly valves:
The relationship between the opening of butterfly valves and flow rate is basically a linear proportional change. If used to control flow, its flow characteristics are closely related to the flow resistance of the piping. For example, if two pipelines are installed with the same valve diameter and form, but the pipeline loss coefficient is different, the flow rate of the valve will also vary greatly.
If the valve is in a state of large throttling amplitude, the back of the valve plate is prone to cavitation, which may damage the valve. Generally, it is used at an angle of 15 °.
When the butterfly valve is in the middle opening position, the opening shape formed by the valve body and the front end of the butterfly plate is centered on the valve shaft, and different states are formed on both sides. One side of the butterfly plate front end moves in the direction of water flow, while the other side moves against the direction of water flow. Therefore, one side of the valve body and the valve plate form a nozzle shaped opening, and the other side forms a throttle hole shaped opening. The nozzle side has a much faster flow rate than the throttle side, and negative pressure is generated below the throttle side valve, often causing rubber seals to fall off.
The operating torque of butterfly valves varies due to differences in opening degree and valve opening and closing direction. For horizontal butterfly valves, especially large diameter valves, the torque generated by the difference between the upper and lower water heads of the valve shaft due to water depth cannot be ignored. In addition, when the elbow is installed on the inlet side of the valve, a bias flow is formed, and the torque will increase. When the valve is in the middle opening, the operating mechanism needs to be self-locking due to the action of water flow torque.