The disadvantage of the rubber seal butterfly valve is that when it is used for throttling, cavitation will occur due to improper use, causing the rubber seat to peel off and damage. For this reason, metal-sealed butterfly valves have been developed internationally, and the cavitation zone has been reduced. In recent years, my country has also developed metal-sealed butterfly valves. In Japan, comb-shaped butterfly valves with cavitation resistance, low vibration and low noise have also been developed in recent years.
Generally, the life of the butterfly valve sealing seat is 15-20 years for rubber and 80-90 years for metal under normal conditions. However, the correct selection depends on the requirements of the working conditions.
The relationship between the opening degree of the metal sealing butterfly valve and the flow rate basically changes linearly. If it is used to control flow, its flow characteristics are also closely related to the flow resistance of the piping. For example, two pipelines are installed with the same valve diameter and form, but the pipeline loss coefficient is different, and the flow rate of the valve will also be very different. If the valve is in a state with a large throttle range, the back of the valve plate is prone to cavitation, which may damage the valve. Generally, it is used outside 15°.
When the metal seal butterfly adjustment 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 are formed to complete different states. The front end of the butterfly plate on one side moves in the direction of the flowing water, and the other side flows backward. Therefore, one side of the valve body and the valve plate form a nozzle-like opening, and the other side is similar to a throttle opening. The nozzle side has a much faster flow rate than the throttle side, and the throttle side valve will produce negative Pressure, rubber seals often fall off.
The operating torque of the metal seal butterfly adjustment has different values ​​due to the different opening and closing directions of the valve. The horizontal butterfly valve, especially the large-diameter butterfly valve, due to the depth of water, the torque generated by the difference between the upper and lower water heads of the valve shaft cannot be ignored. In addition, when an 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 the water flow torque.

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Major products: Butterfly Valve, Ball Valve,Gate Valve, Check Valve, Globe Vavlve,Y-Strainers, Electric Acurator , Pneumatic Acurators .