Control Duty Classifications:

• Class A: ON-OFF Type (On/Off)

• • Function: The actuator is required to drive the valve through its entire stroke from fully open to fully closed (and vice versa).

  • Typical Use: Applications where valves are either fully open or fully closed.

• Class B: Fine-Tuning/Positioning Adjustment Type

  • Function: The actuator occasionally moves the valve to any position (fully open, intermediate, or fully closed).

  • Typical Use: Applications requiring occasional adjustment but not continuous movement.

• Class C: Modulating Type

  • Function: The actuator frequently moves the valve between fully open and fully closed positions.

  • Typical Use: Applications that require continuous and frequent modulation of valve position.

• Class D: Continuous Modulating Type

  • Function: The actuator continuously moves the valve to any position between fully open and fully closed.

  • Typical Use: Applications with continuous or very frequent adjustments.

Actuator Life Cycle Requirements:

The actuator’s design must comply with the specified operational life standards. For modulating and continuous modulating actuators, their durability is based on continuous starts within 30% of their stroke.

Life Testing for Part-turn Actuators:

• Operating Cycles: A cycle includes two directions of 90° stroke (open 90° + close 90°), based on at least 30% rated torque average load, with at least 5% of rated torque at each end of the stroke.

• Start-up Cycles: One start-up involves moving the actuator at least 1% of its stroke with at least 30% rated torque.

Life Testing for Multi-Turn Actuators:

Life Testing for Linear Actuators:

Adjustment Frequency Requirements (Per Hour):

Part-Turn Actuators:

Multi-Turn Actuators:

Linear Actuators: