What is the difference between a ball valve and a butterfly valve? What is the difference between a ball valve and a butterfly valve?

What is the difference between a ball valve and a butterfly valve?

The difference between ball valve and butterfly valve

The biggest difference between a ball valve and a butterfly valve is that the opening and closing part of a butterfly valve is a plate, while that of a ball valve is a ball. The valve plate of a butterfly valve and the valve core of a ball valve both rotate around their respective axes; the valve plate of a ball valve moves up and down along the axis; both butterfly valves and gate valves can adjust the flow rate by opening; this is not easy to do with a ball valve.

The characteristics of butterfly valves are fast opening and closing speed, simple structure, and low cost, but their sealing and pressure bearing capacity are poor; the characteristics of ball valves are similar to those of gate valves, but due to the limitations of volume and opening and closing resistance, it is difficult to achieve large diameters.

The structural principle of butterfly valve is particularly suitable for making large-diameter valves. The butterfly plate of butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical channel of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, and the rotation angle is between 0° and 90°. When it rotates to 90°, the valve is fully open. It has a simple structure, low cost, and a large adjustable range. Ball valves are usually suitable for liquids and gases that do not contain particulate impurities. The fluid pressure loss is small, the sealing performance is good, and the cost is high. Relatively speaking, the sealing performance of ball valves is better than that of butterfly valves. The sealing of ball valves relies on the long-term extrusion of the valve seat on the spherical surface, and the wear is faster than that of hemispherical valves. The sealing of ball valves is usually made of flexible materials, which is also difficult to use in high-temperature and high-pressure pipelines. The sealing ring of butterfly valves is made of rubber, which is far inferior to the metal hard sealing performance of hemispherical valves, ball valves, and gate valves. After long-term use of hemispherical valves, the valve seat will also be slightly worn, and it can continue to be used by adjustment. During the opening and closing process of the valve stem and packing, you only need to rotate the valve stem 90 degrees. If there is any sign of leakage, tighten the packing gland. Just tighten a few bolts and the packing will not leak. Other valves with small leakage can still be used, but valves with large leakage must be replaced.

The ball valve is operated by the clamping force of the valve seats at both ends during opening and closing. It has larger opening and closing torque than the semi-ball valve. The larger the nominal diameter, the more obvious the difference between the opening and closing torque. The opening and closing of the butterfly valve must overcome the deformation of the rubber to achieve, and the torque is relatively large. The operation time of gate valves and stop valves is long and laborious.

The ball valve is the same type of valve as the plug valve, except that its closing piece is a sphere, which rotates around the center line of the valve body to open and close. The ball valve is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline.