Difference between Ball Valve and Butterfly Valve

The biggest difference between butterfly valves and ball valves is that the butterfly valve is fully opened or closed by using a disc while the ball valve uses a hollow, perforated and pivoting ball to do that. Both the disc of the butterfly valve and the valve core of the ball valve rotate around their own axis. The butterfly valve can regulate the flow through its open degree while the ball valve are not convenient to do this.

Butterfly valve is characterized by fast opening and closing, simple structure and low cost, but its tightness and bearing capacity are not good. The features of ball valves are similar to those of gate valves, but due to the limitation of volume and opening and closing resistance, it is difficult for the ball valve to be a large diameter one.
 

The structure principle of butterfly valves makes them especially suitable to be made into large diameter ones. The disc of the butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical passage of the butterfly valve body, the disc rotates around the axis. When it is rotated a quarter turn, the valve is fully open. The butterfly valve has simple structure, low cost and wide adjustable range. Ball valves are usually used for liquids and gases without particles and impurities. These valves are with small fluid pressure loss, good sealing performance and high cost.

In comparison, the sealing of ball valve is better than butterfly valve. The ball valve seal is depending on the press on the spherical surface by the valve seat for a long time, which is sure to wear faster than the semi-ball valve. The ball valve is usually made of flexible sealing material, and it is difficult to use in high temperature and high pressure pipelines. The butterfly valve has a rubber seat, which is far from the metal hard sealing performance of semi-ball valves, ball valves and gate valves. After long-term use of the semi-ball valve, the valve seat will also be slightly worn, and it can be continuously used through adjustment. When the stem and packing are opened and closed, the stem only needs to rotate a quarter turn. When there is any sign of leakage, press the bolt of the packing gland to realize no leakage. However, other valves are still barely used with small leakage, and valves are replaced with large leakage.

In the process of opening and closing, the ball valve operates under the holding force of the valve seats at both ends. Compared with the semi-ball valve, the ball valve has larger opening and closing torque. And the larger the nominal diameter, the more obvious the difference of opening and closing torque. The opening and closing of the butterfly valve is realized by overcoming the deformation of rubber. However, it takes a long time to operate gate valves and globe valves and it is also laborious to do that.

Ball valve and plug valve are of the same type. only the ball valve has a hollow ball to control flow through it. Ball valves are mainly used to cut off, distribute and change the flow direction of the medium in pipelines.