Spring-return (single) actuators supply power/pressure to only one side of a piston, the spring powers the alternate side moving the valve to open or close position.
In contrast, the double-acting actuator uses piston element to operate the valve therefore both chambers require pressurization.
单作用执行机构，有故障位置，双作用执行机构必须通过储气罐，才能实现故障位置，带口径较大的执行机构。
Single acting actuators with fault position, double acting actuators must pass through a storage tank in order to achieve a fault position with a larger diameter.
Spring return and double acting are two common types of actuator configurations, often found in pneumatic or hydraulic actuators.
They work slightly differently:
In this type of actuator, fluid (air or hydraulic fluid) is used to move the actuator in one direction, and a spring is used to return the actuator to its original position when the fluid is removed. This means that the actuator has one powered direction and one spring-return direction.
If you lose pressure, the spring will return the actuator to its failsafe position. This is beneficial in safety-critical applications where a certain position (open or closed) must be maintained in the event of a power or pressure loss.
In a double acting actuator, fluid is used to move the actuator in both directions. This means that the actuator has two powered directions - forward and backward (or open and close).
This can provide more force than a spring return actuator, but it doesn’t have a failsafe position if you lose pressure - it will simply stay in its last position. Double acting actuators can be more effective for larger valves or systems where more power is needed to move the actuator.
The choice between spring return and double acting will depend on the specific requirements of your application. For instance, you might choose a spring return actuator for a valve that must be fail-closed for safety reasons, while a double acting actuator might be better for a larger valve that requires more force to operate.