Since the ball valve usually uses rubber, nylon and PTFE as the material of the seat sealing ring, its service temperature is limited by the material of the seat sealing ring. The cut-off function of the ball valve is accomplished by pressing the metal ball against the plastic valve seat under the action of the medium (floating ball valve). Under the action of a certain contact pressure, the valve seat sealing ring undergoes elastic-plastic deformation in local areas. This deformation can compensate for the manufacturing accuracy and surface roughness of the sphere and ensure the sealing performance of the ball valve.
