A double-acting actuator uses air for both directions; a spring-return actuator uses air in one direction and springs for the return stroke. Choose the action from the required valve behavior, then size and match the complete valve-actuator assembly.
Start with the required valve behavior
State whether the valve must open, close or follow another defined sequence when control power or supply air is lost. “Spring return” does not automatically mean fail closed: the assembled orientation, pilot circuit and process requirement determine the intended return action. Review the complete assembly instead of treating actuator type alone as a safety guarantee.
| Question | Double acting | Spring return |
|---|---|---|
| What produces motion? | Air drives both directions | Air drives one direction; springs return it |
| What data is needed for sizing? | Valve torque through travel and minimum available air pressure | Valve torque plus air-stroke and spring-stroke torque through travel |
| What must the RFQ define? | Control circuit and loss-of-supply behavior | Required return direction, spring set and control circuit |
Compare AT-DA and AT-SR using the published tables
Use the AT-DA double-acting actuator data for air-driven opening and closing. Use the AT-SR spring-return actuator data when a spring return is part of the required sequence. The AT-SR reference table distinguishes air and spring torque at start/end positions; one maximum torque value is not enough to select the assembly.
Catalog model examples help identify the family, but final sizing needs the valve manufacturer's torque requirement under the stated medium, pressure, temperature and seat condition. Provide the minimum air pressure actually available at the actuator during operation, not only the compressor set point. Agree the sizing allowance for the application rather than applying a universal percentage from an unrelated example.
Check mounting and accessories together
Confirm the valve mounting flange, stem dimensions and orientation, bracket/coupling arrangement, rotation and installation space. A similar actuator footprint does not prove the shaft and valve interface match.
List the required pilot solenoid, voltage and wiring, limit-switch feedback, positioner if needed, and air preparation. The 4V200 directional-valve page provides a compressed-air control reference; mounting and circuit suitability still need confirmation. A directly mounted NAMUR control valve and a separately piped valve should not be assumed interchangeable.
RFQ checklist for a complete review
Send valve type, DN/port size, medium, operating pressure and temperature, valve torque data, minimum air pressure, action type, required return position and cycle frequency. Add the valve drawing or nameplate, mounting interface, accessory signals, environment and quantity.
For a complete ball or butterfly package, use the valve package RFQ checklist. Ask for the selected actuator code, mounting arrangement and accessory list to be shown together in the quotation so that the interfaces can be reviewed before ordering.
| Parameter | Value |
|---|---|
| Double acting | Air opens and air closes the actuator. |
| Spring return | Air moves one direction and spring returns to fail position. |
| Key data | Valve torque, air pressure, rotation angle and safety logic. |
| Mounting | Confirm ISO mounting pattern, shaft and bracket requirements. |
| Accessories | Limit switch, solenoid valve, positioner and air preparation. |
Frequently Asked Questions
- FAQ Is spring return always safer?
The correct return direction depends on the process and complete control arrangement. Actuator type alone does not establish system safety. - FAQ Can one actuator fit ball and butterfly valves?
It may, but valve torque, mounting flange, stem, coupling and travel must all match. - FAQ Which air pressure should be used for sizing?
Provide the minimum pressure available at the actuator during the required stroke, together with the operating range.
Need a quotation?
Send the page link, quantity, drawings and working conditions to Kailing for review.