The characteristics of the butterfly valve is to open and close fast, simple structure, low cost, but the sealing tightness and pressure range is limited. The ball valve is similar with gate valve, but it is not easy to make large diameter due to the limit of volume and opening and closing force.
Structure principle of butterfly valve is particularly suitable to produce large diameter. The disc of butterfly valve is to install the pipe diameter direction. In the cylindrical channel of the valve body, the disc around the axis of rotation, the rotation angle between 0°~ 90° rotation, When it reach to 90°, the valve is full open conditions. It is simple structure, low cost, large nominal diameter range. Ball valve is usually applied to liquid, gas which include no grain impurities, with small fluid pressure loss. It has good sealing performance, high cost. In comparison with butterfly valve, the sealing performance is better than butterfly valve. The seal of ball valve is to rely on seat force of by seat spring. The valve seal of ball valve is usually flexible material, which is difficult to use in high temperature and high pressure piping. The seal of butterfly valve is usually rubber as an intermediary, it is far away from ball valve, gate valve. If it is a V-shape ball valve, it also has abrasion, but better than soft seal ball valve and rubber seal butterfly valve.
Ball valve rotates to process in both ends of seat pretight force for operation. The torque force is bigger than V-shape ball valve, the larger nominal diameter, the larger torque difference of the opening and closing. It is more obvious. The butterfly valve is to overcome the rubber deformation to achieve the opening and closing. It need greater torque. But for gate valve, globe valve, the operation time is long and strenuous.
Ball valve and plug valve are the same type according to the valve closure. It is just a ball (sphere), a ball around the body centerline rotation to achieve open and close for valve operation. In pipeline system, ball valve is mainly used to cut-off, distribution and change the media flow direction.