Actuator selection starts with the valve’s required torque envelope and the lowest available supply pressure. The actuator must provide adequate torque throughout the required stroke while staying within the valve shaft and mounting limits.
Use the correct valve load
Request breakaway, running and seating torque for the selected valve, seat, differential pressure and medium. Include the possibility of deposits or long idle periods where relevant. A clean-water torque table may be a starting reference, but it may not represent abrasive stock or a crystallizing process.
Check all critical positions
Pneumatic output can vary with angle and actuator design. For spring-return units, both air-powered travel and spring-powered travel must be checked at their critical points. A single maximum output number does not demonstrate that the assembly can complete the required movement. Include the specified margin once, using a clear basis.
Do not oversize without checking limits
Excessive actuator torque can overload shafts, keys, brackets or stops. Verify the allowable mechanical loads and the maximum supply pressure. Set travel stops and positioner limits according to the approved assembly instructions. Final approval should identify the actuator size, operating air range, torque comparison and required failure position.
Practical checklist
- Minimum air pressure at the actuator under demand.
- Worst-case valve torque versus travel.
- Spring-end and air-end conditions if applicable.
- Shaft, coupling and mounting torque limits.
Discuss your application
Send the process conditions and required valve function for a configuration review. Request a technical quotation ↗