Actuators
According to ISO 22153, a multi-turn actuator is an actuator which can transmit torque to the valve or the valve gearbox for at least one revolution and can be capable of withstanding thrust. In most applications, multi-turn valves require considerably more turns than one revolution. In addition, gate valves are often equipped with rising stems. Therefore, the output drive shaft of SA and TIGRON multi-turn actuators is designed as a hollow shaft housing the valve stems for these applications.
Class A: OPEN-CLOSE duty. The actuator is required to operate the valve across its entire travel from the fully open position to the fully closed position or vice versa.
Class B: Inching, positioning or positioning duty. The actuator is required to occasionally operate the valve to any position (fully open, intermediate and fully closed).
Class C: Modulation or modulating duty. The actuator is required to frequently operate the valve to any position between fully open and fully closed.
Class D: Continuous modulating. The actuator is required to continuously operate the valve to any position between fully open and fully closed.
