Butterfly valve is often used in water system. Because of its small volume and high cost performance, valve has become a commonly used valve in pipeline. The main products of butterfly valve are wafer soft seal butterfly valve and flange butterfly valve. Although there are fewer types of butterfly valves than gate valves, there are many differences in adapting to different working conditions. The butterfly valve is mainly divided into central type and eccentric type according to its structure, and the eccentric type is divided into single eccentricity, double eccentricity and three eccentricity.

1. Principle of butterfly valve:

The butterfly valve adopts the structure that the valve plate rotates along the center line, and the valve volume is small. Rotate the handle or worm gear 90 degrees to make the valve plate parallel to the medium flow direction, and then open the valve. Therefore, the butterfly valve has the characteristics of simple structure, small volume, light weight, small installation size, convenient operation, fast opening and closing, etc. It also has sealing and flow regulation characteristics. However, due to the large disc resistance and the great influence of medium pressure on the opening and closing of the valve, it is not suitable for high-pressure environment.

2. The performance advantages of butterfly valve mainly focus on small volume, simple structure, fast opening and closing, etc. The disadvantages are also obvious. The pressure loss of the flowing medium in the pipeline is large, and it is difficult to open and close in the high-pressure environment.

3. Different structures of butterfly valves: the sealing performance and service life of centerline butterfly valve, single eccentric butterfly valve, double eccentric butterfly valve and three eccentric butterfly valve are improved in turn, but the difficulty and cost of structural shortage are increased. Unless there are special working conditions, it is often necessary to choose a more economical and appropriate butterfly valve.

In case of failure of butterfly valve, how to eliminate it in time:

1. The leakage at both ends of the butterfly valve is caused by the gaskets on both sides. The pressing force of pipe flange is uneven or not pressed. The sealing gasket can be replaced to compress the flange bolts evenly.

2. The leakage of butterfly valve bonnet is caused by the butterfly valve plate, and there are sundries in the sealing ring. The sealing position of butterfly valve and sealing ring is incorrect or the outlet flange bolts are pressed unevenly. The pressure test deviation does not meet the requirements. Remove impurities including valve cavity. Adjust the turbine or electric actuator and limit screw to achieve the exact position of valve closing. The pressure test deviation does not meet the requirements. We should rotate according to the deviation of the arrow.