The actuator and adjustment mechanism of the pneumatic actuator is a unified whole, and the actuators are film type, piston type, fork-type, and rack and pinion type. The piston-type has a long stroke and is suitable for occasions requiring large thrust; while the diaphragm type has a small stroke and can only directly drive the valve stem. The fork-type pneumatic actuator has the characteristics of large torque, and small space and the torque curve is more in line with the torque curve of the valve, but it is not very beautiful; it is often used on valves with high torque. The rack-and-pinion pneumatic actuator has the advantages of simple structure, stable and reliable action, and safety and explosion-proof. It is widely used in power plants, the chemical industry, oil refining, and other production processes with high safety requirements.
When the butterfly valve is fully opened, it has less flow resistance. When the opening is between about 15° and 70°, sensitive flow control can be performed, so the application of butterfly valves is very common in the field of large-diameter adjustment. Since the movement of the butterfly valve plate is wiping, most butterfly valves can be used for media with suspended solid particles. Depending on the strength of the seal, it can also be used for powdered and granular media.
