Pneumatic ball valve is composed of two parts: a cylinder and a ball valve. The cylinder serves as the driving element, and the output shaft provides power to drive the ball core of the ball valve to rotate, achieving functions such as pipeline switching, adjustment, and flow direction switching. For example, pneumatic O-shaped cut-off ball valve, pneumatic V-shaped regulating ball valve, pneumatic three-way reversing ball valve. Common accessories include solenoid valve, travel switch, filter and pressure reducing valve, electrical valve locator, etc. Pneumatic ball valve has low flow resistance, compact structure, good sealing, and a wide range of applications.
          
Pneumatic ball valves are divided into two types based on the action mode of the cylinder: single acting cylinder and double acting cylinder. Common types of cylinders include AT cylinder, GT cylinder, AW cylinder, etc.
          
There is a reset spring inside the single acting cylinder, and the air pressure enters the cylinder through the solenoid valve, pushing the piston to move. At the same time, the piston compresses and stores energy. After the solenoid valve releases the air pressure from the cylinder, the spring pushes the piston to move, driving the ball core of the ball valve to automatically reset and maintain a closed or open state.
           
There is no reset spring inside the double acting cylinder. By relying on the power on and off of the solenoid valve, the direction of the solenoid valve supply is switched to achieve the reciprocating switch action of the cylinder, driving the ball valve to open or close.
          
The difference between the two:
1. Is there a return spring inside the cylinder? There is a return spring inside the single acting cylinder, but there is no return spring inside the double acting cylinder.
          
2. Different optional solenoid valves. Single acting cylinders are equipped with a two position three-way solenoid valve, while double acting cylinders are equipped with a two position five way solenoid valve.
             
3. Different cylinder sizes are required for ball valves of the same caliber. Single acting cylinders not only need to consider the torque of the ball valve, medium pressure, but also the thrust of the spring, so the inner diameter of the cylinder needs to be larger. Double acting cylinders do not have springs, so the inner diameter of the cylinder is smaller for ball valves of the same caliber.
          
4. The installation of manual switch mechanism is different. The single acting cylinder has a spring inside, and the torque of the manual switch mechanism of the single acting cylinder is greater than that of the double acting cylinder because it also needs to overcome the torque generated by the thrust of the spring. If there is no spring inside the double acting cylinder, it is smaller.
          
5. Different functions can be achieved. A single acting cylinder can automatically reset the pneumatic ball valve in the event of a gas source failure and no pressure in the gas source. The ball valve remains open or closed, and its on/off state is very important for the safety of the production process. In this case, a single acting pneumatic ball valve must be selected with a manual switch mechanism. A double acting pneumatic ball valve is used on pipelines where the on/off state is not very important for production safety.
          
6. The output torque curve of the cylinder is different. The output torque of the single acting cylinder spring gradually decreases with the rotation of the output shaft. The minimum torque still needs to be maintained to drive the ball core of the ball valve to rotate. The output torque of the double acting cylinder is a constant straight line and increases with the increase of the air source pressure.
          
7. The cost of cylinders is different. For cylinders with the same diameter, the cost of a single acting cylinder is higher due to the addition of a reset spring. The cost of a double acting cylinder is lower.