The operation torque data of soft sealed trunnion ball valve in the following table are calculated based on normal temperature and clean medium. As selecting actuator, it is suggested that drive torque of actuator be more than 1.3 times the operation torque of ball valve at least. เท case of high temperature and low temperature working conditions or unclean medium, it is possible that valve operation torque gets increased, which should be taken into full consideration as selecting actuators. Operation torque for metal to metal sealed trunnion ball valve is about 3~4 times that of soft sealed trunnion ball valve.