Double eccentric butterfly valve, also known as high-performance butterfly valve, is a type of valve widely used in many industrial fields. The following is a detailed introduction to the double eccentric butterfly valve: 

 1. Definition and structure 

 The center of the valve shaft of the double eccentric butterfly valve has two offsets, which deviates from both the center of the butterfly plate and the center of the valve body channel. This structural design allows the butterfly plate to quickly detach from the valve seat when the valve is opened, which greatly reduces the scratching phenomenon between the butterfly plate and the valve seat, reduces the opening resistance, reduces wear, and improves the service life of the valve seat. 

 2. Working principle 

 The double eccentric butterfly valve drives the butterfly plate to rotate in the valve body by rotating the valve stem, so as to realize the flow control of the medium. When the valve stem rotates, the butterfly plate rotates, changing the circulation area of the medium in the pipeline, thus achieving the purpose of regulating the flow rate. In the closed state, the butterfly plate fits closely with the valve seat to form an effective seal. 

 3. Features and advantages 

 Simple structure: The design of the double eccentric butterfly valve is simple and clear, with a compact structure and easy to install and maintain. 

 Easy to operate: The switch operation of the valve is very simple. You only need to rotate the valve stem to open and close, which is labor-saving and convenient. 

 Small fluid resistance: Because the contact area between the butterfly plate and the medium when rotating in the valve body is small, the resistance of the fluid when passing through the valve is also small, which reduces energy consumption. 

 Good sealing performance: The double eccentric butterfly valve adopts high-quality sealing materials and advanced sealing technology to ensure that the valve has good sealing performance and can effectively prevent leakage. 

 Wide scope of application: Double eccentric butterfly valve can be used in water supply and drainage, sewage, construction, petroleum, chemical industry, light textile, papermaking, hydropower, metallurgy, energy and other fields. It is suitable for a variety of corrosive and non-corrosive gases, liquids, semi-fluids and solid powder pipelines and containers as regulating and interception equipment. 

 4. Installation and maintenance 

 Installation: When installing a double eccentric butterfly valve, it should be ensured that the arrow direction of the valve is consistent with the direction of medium flow to avoid reverse installation. At the same time, the flange bolt should be tightened with a torque wrench to ensure that the initial contact between the flange and the gasket is as flat and parallel as possible. 

 Maintenance: In order to maintain the good performance and service life of the double eccentric butterfly valve, regular maintenance and upkeep are required. This includes checking the sealing performance of the valve, cleaning the dirt inside the valve, checking and replacing the damaged seals, etc. 

 In summary, valve corrosion prevention needs to be based on material selection and surface coating. As mentioned above, double eccentric butterfly valves have been widely used in many industrial fields with their simple structure, easy operation, small fluid resistance, good sealing performance and wide scope of application.