Valve actuation should be selected as a complete valve-and-control package, not as an afterthought. The correct actuator must reliably overcome the valve torque under the highest pressure differential, while matching the site utilities, automation architecture and shutdown philosophy.
1. Start with the valve and service conditions
Confirm valve type, nominal size, pressure class, medium, temperature and maximum differential pressure. Butterfly, ball, plug and gate valves have different torque profiles. Abrasive, viscous, cryogenic or marine services can require additional torque margin, special seals or corrosion protection.
Quarter-turn valves
Butterfly and ball valves normally use 90° electric or pneumatic actuators. Verify breakaway and seating torque.
Linear valves
Gate, globe and control valves typically require multi-turn or linear actuators matched to stem thrust and travel.
Safety-critical duties
Define the desired fail-open, fail-close or fail-in-place position before choosing the actuator configuration.
2. Compare actuator types
| Actuator | Best fit | Key checks |
|---|---|---|
| Electric | Remote control where electrical power and precise positioning are needed | Voltage, enclosure rating, torque range, duty cycle, control signal and manual override |
| Pneumatic | Fast cycling, compressed-air sites and spring-return shutdown duties | Air pressure/quality, rack-and-pinion or scotch-yoke type, solenoid, positioner and fail action |
| Manual gear operator | Local, infrequent operation with no automation requirement | Handwheel force, gear ratio, lockability and operating access |
3. Set a practical torque margin
Use the valve manufacturer’s torque data rather than nominal size alone. Allow margin for pressure, packing friction, temperature, aging and deposits. Oversizing should still be controlled: excessive output can damage valve components or reduce modulation accuracy.
4. Define controls and feedback
For on/off automation, specify the required command signal and open/close feedback. For regulating service, define the positioner input, desired control accuracy and fail action. For marine, outdoor or hazardous-area projects, include certification, ingress protection and ambient conditions in the enquiry.
Actuator selection checklist
- Valve type, size, material and end connection
- Medium, pressure, temperature and maximum differential pressure
- Required operating speed and duty cycle
- Electric supply or available instrument-air pressure
- On/off or modulating control; feedback and communication needs
- Fail-safe position and emergency shutdown requirement
- Installation environment, certification and corrosion protection