1. The relationship between butterfly valve opening flow rate is basically linear proportional change. 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 form of the valve installed in the two pipelines are the same, the loss coefficient of the pipeline is different, the flow rate of the valve will be greatly different.
2. If the valve is in a large throttling range, the back of the valve plate is prone to cavitation, which may damage the valve. Generally, it is used outside 15 ℃.
3. When the butterfly valve is in the middle opening, the opening shape formed by the valve body the front end of the butterfly plate is centered on the valve shaft, the two sides form different states. The front end of the butterfly plate on one side moves along the flow direction, the other side moves against the flow direction. Therefore, one side of the valve body the valve plate form a nozzle shaped opening, the other side is similar to a throttling orifice type opening. The flow rate on the nozzle side is much faster than that on the throttling side, while throttling Negative pressure will be generated under the side valve, the rubber seal will often fall off.
4. The operating torque of butterfly valve varies with the opening closing direction of the valve. The torque of horizontal butterfly valve, especially the large diameter valve, due to the water depth the difference between the upper lower head of the valve shaft, can be ignored. In addition, when the elbow is installed at the inlet side of the valve, the bias current will be formed the torque will be increased. When the valve is in the middle opening, the operating mechanism needs self-locking due to the action of hydrodynamic moment.
At present, butterfly valve is widely used in many fields such as petroleum, chemical industry, metallurgy, hydropower so on. In the well-known butterfly valve technology, its sealing form mostly adopts the sealing structure, the sealing materials are rubber, polytetrafluoroethylene, etc. Due to the limitation of structural characteristics, it is suitable for high temperature, high pressure, corrosion resistance, wear resistance other industries.