Sealing is good, but all spheres of work under medium load to export sealing ring, so should consider to seal material can withstand the working load of sphere medium, under high pressure shock, sphere migration may occur. In this structure, is generally used in low pressure ball valve.
Ball valve ball is fixed, does not produce mobile after compression. Fixed ball valves have a floating ball valve seat, the medium pressure, mobile seat, make the seal compression on the ball, to ensure the seal. Usually mounted on the upper and lower shaft with ball bearing, the operating torque is small, suitable for high pressure and large diameter of the valve.
To reduce the number of ball valve operating torque and increase the reliability of the seal, and the oil seal ball valve, both betting special lubricant between the sealing surface, in order to form a layer of oil film, which increases the sealing, and reduce operating torque, suitable for high pressure large diameter ball valve.