Operating principle and installation instructions of butterfly valve
The relationship between the opening of butterfly valve and the flow is basically linear. If it is used to control the flow, its flow characteristics are also closely related to the flow resistance of the piping. For example, the diameter and form of the valves installed in the two pipelines are all the same, and the flow rate of the valves will vary greatly with the loss coefficient of the pipelines.
If the valve is in the state of large throttling range, cavitation is easy to occur on the back of the valve plate, which may damage the valve 15° For external use.
When the butterfly valve is in the middle opening, the opening shape formed by the valve body and the front end of the butterfly plate is centered on the valve shaft, and the two sides form different states. The front end of the butterfly plate on one side moves along the flow direction, and the other side moves against the flow direction. Therefore, the valve body and the valve plate on one side form a nozzle like opening, and the other side is similar to an orifice like opening, Negative pressure will be generated under the throttle side valve, and the rubber seal will often fall off.
The operating torque of butterfly valve varies with the opening and the opening and closing direction of the valve. The horizontal butterfly valve, especially the large-diameter valve, can not be ignored due to the water depth and the difference between the upper and lower ends of the valve shaft. In addition, when the elbow is installed at the inlet side of the valve, the deflection flow will be formed and the torque will be increased. When the valve is in the middle opening, the operating mechanism needs to be self-locking due to the action of hydrodynamic moment.