What is the difference between ball valves and butterfly valves?

The big difference between the two is that the opening and closing parts of a butterfly valve are a plate, while 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 own axis; The valve plate of the gate valve moves up and down along the axis; Butterfly valves and gate valves can adjust flow rate through opening degree; Ball valves are not convenient to achieve this. The characteristics of butterfly valves are fast opening and closing speed, simple structure, low cost, but poor tightness and pressure bearing capacity. The characteristics of ball valves are similar to those of gate valves, but due to limitations in volume and opening and closing resistance, it is difficult to achieve large diameters. The structural principle of butterfly valves is particularly suitable for making large-diameter valves. The butterfly plate of butterfly valves is installed in the diameter direction of pipelines. In the cylindrical channel of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, with a rotation angle between 0 and 90 degrees. When it rotates to 90 degrees, 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 without particulate impurities, with low fluid pressure loss, good sealing performance, and high cost. Compared to butterfly valves, ball valves have better sealing.

Ball valve sealing relies on the long-term compression of the valve seat on the spherical surface, which will definitely wear out faster than hemispherical valves. The sealing of ball valves is usually made of flexible materials, and it is also difficult to use in high-temperature and high-pressure pipelines. Butterfly valve sealing is mediated by rubber, and its metal hard sealing performance is far inferior to that of hemispherical valves, ball valves, and gate valves. After long-term use, the valve seat of the hemispherical valve will also experience slight wear and tear. It can be adjusted to continue use. During the opening and closing process, the valve stem and packing only need to rotate 90 degrees. When there are signs of leakage, tighten the bolts of the packing gland a little more to achieve no leakage at the packing root. However, other valves are still barely used for small leaks, and replace the valve for large leaks.

The ball valve operates under the clamping force of the valve seats at both ends during the opening and closing process. It has a larger opening and closing torque than a hemispherical valve, and the larger the nominal diameter, the more obvious the difference in opening and closing torque. The opening and closing of a butterfly valve needs to overcome the deformation of the rubber, resulting in a larger torque. However, gate valves and globe valves require a long and laborious operation time. Ball valve and plug valve belong to the same type of valve, with only its closing part being a sphere. The sphere rotates around the valve body line to achieve opening and closing. Ball valves are mainly used in pipelines to cut off, distribute, and change the flow direction of the medium.