what is double acting and single acting pneumatic rotary actuator

A pneumatic actuator is a device used to control valves, valve balls or other mechanical equipment. It is driven by gas to perform opening, closing or regulating operations. Pneumatic actuators are mainly divided into two types: single-acting and double-acting.

Single-acting pneumatic actuator (Single-Acting):

Working principle: Single-acting pneumatic actuator has only one side of the pneumatic piston (cylinder) affected by the air source. When the air source is pressurized, the cylinder moves from one position to another, completing the corresponding action (usually opening or closing a valve). During reverse movement, a spring or other mechanical device is responsible for returning the cylinder to its original position.
Features: Relatively simple, low cost, suitable for some simple application scenarios. In the event of air supply failure, a mechanical device such as a spring is usually used to return the actuator to a safe position.
Double-acting pneumatic actuator (Double-Acting):

Working principle: Double-acting pneumatic actuator can accept the action of air source on both sides of the cylinder. By alternately pressurizing and exhausting air at both ends of the cylinder, the forward and reverse movements of the cylinder can be achieved. This design allows the actuator to perform work in both directions and is typically used in applications that require frequent adjustments or require more power.
Features: It has greater control flexibility and can realize two-way adjustment. It is suitable for systems that require high movement accuracy. However, the cost may be higher relative to single-acting actuators.
The choice of single-acting or double-acting pneumatic actuator usually depends on the specific application requirements:

Simple Applications: For some simple switching or shut-off valves, a single-acting actuator may be sufficient and more economical.

Bidirectional control required: If the system requires frequent adjustments or requires greater control flexibility, a double-acting actuator is a more suitable choice.

Safety requirements: In some scenarios with higher system safety requirements, single-acting actuators have better safety because they usually automatically return to a safe position when the air source fails.