4. Calculation of total friction torque The friction torque of the valve is calculated according to the following formula: MF=MQZ+MFT+MFC (N-M) (4), where: friction torque of MQ ball in the valve seat; Friction torque between MFT packing and valve rod; Friction torque analysis of MFC valve stem head The force generated by pneumatic ball valve shows that under the action of medium, the floating ball moves towards the outlet end, and the force generated is all borne by the valve seat seal ring at the outlet. The valve seat seal ring in front of the ball does not bear the force and does not affect the friction torque.

① Pneumatic actuator: divided into double acting type and single acting type (air to open type and air to close type).
Double acting pneumatic actuator: two position control for valve opening and closing.
Single acting pneumatic actuator (spring return type): when the air circuit is cut off or fails, the valve will automatically open or close.